New upstream release (6.8p1).

1 files changed, 1832 insertions, 1025 deletions

diff --git a/packet.c b/packet.c
index 6e7b87757..b1219c85b 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.198 2014/07/15 15:54:14 millert Exp $ */
+/* $OpenBSD: packet.c,v 1.208 2015/02/13 18:57:00 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -39,9 +39,9 @@
 
 #include "includes.h"
  
+#include <sys/param.h>  /* MIN roundup */
 #include <sys/types.h>
 #include "openbsd-compat/sys-queue.h"
-#include <sys/param.h>
 #include <sys/socket.h>
 #ifdef HAVE_SYS_TIME_H
 # include <sys/time.h>
@@ -57,29 +57,35 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <limits.h>
 #include <signal.h>
 #include <time.h>
 
+#include <zlib.h>
+
+#include "buffer.h"     /* typedefs XXX */
+#include "key.h"        /* typedefs XXX */
+
 #include "xmalloc.h"
-#include "buffer.h"
-#include "packet.h"
 #include "crc32.h"
-#include "compress.h"
 #include "deattack.h"
 #include "compat.h"
 #include "ssh1.h"
 #include "ssh2.h"
 #include "cipher.h"
-#include "key.h"
+#include "sshkey.h"
 #include "kex.h"
+#include "digest.h"
 #include "mac.h"
 #include "log.h"
 #include "canohost.h"
 #include "misc.h"
 #include "channels.h"
 #include "ssh.h"
-#include "ssherr.h"
+#include "packet.h"
 #include "roaming.h"
+#include "ssherr.h"
+#include "sshbuf.h"
 
 #ifdef PACKET_DEBUG
 #define DBG(x) x
@@ -99,7 +105,7 @@ struct packet_state {
 struct packet {
         TAILQ_ENTRY(packet) next;
         u_char type;
-        Buffer payload;
+        struct sshbuf *payload;
 };
 
 struct session_state {
@@ -116,26 +122,33 @@ struct session_state {
         u_int remote_protocol_flags;
 
         /* Encryption context for receiving data.  Only used for decryption. */
-        CipherContext receive_context;
+        struct sshcipher_ctx receive_context;
 
         /* Encryption context for sending data.  Only used for encryption. */
-        CipherContext send_context;
+        struct sshcipher_ctx send_context;
 
         /* Buffer for raw input data from the socket. */
-        Buffer input;
+        struct sshbuf *input;
 
         /* Buffer for raw output data going to the socket. */
-        Buffer output;
+        struct sshbuf *output;
 
         /* Buffer for the partial outgoing packet being constructed. */
-        Buffer outgoing_packet;
+        struct sshbuf *outgoing_packet;
 
         /* Buffer for the incoming packet currently being processed. */
-        Buffer incoming_packet;
+        struct sshbuf *incoming_packet;
 
         /* Scratch buffer for packet compression/decompression. */
-        Buffer compression_buffer;
-        int compression_buffer_ready;
+        struct sshbuf *compression_buffer;
+
+        /* Incoming/outgoing compression dictionaries */
+        z_stream compression_in_stream;
+        z_stream compression_out_stream;
+        int compression_in_started;
+        int compression_out_started;
+        int compression_in_failures;
+        int compression_out_failures;
 
         /*
          * Flag indicating whether packet compression/decompression is
@@ -164,7 +177,7 @@ struct session_state {
         int packet_timeout_ms;
 
         /* Session key information for Encryption and MAC */
-        Newkeys *newkeys[MODE_MAX];
+        struct newkeys *newkeys[MODE_MAX];
         struct packet_state p_read, p_send;
 
         /* Volume-based rekeying */
@@ -172,7 +185,7 @@ struct session_state {
         u_int32_t rekey_limit;
 
         /* Time-based rekeying */
-        time_t rekey_interval;  /* how often in seconds */
+        u_int32_t rekey_interval;       /* how often in seconds */
         time_t rekey_time;      /* time of last rekeying */
 
         /* Session key for protocol v1 */
@@ -184,7 +197,7 @@ struct session_state {
 
         /* XXX discard incoming data after MAC error */
         u_int packet_discard;
-        Mac *packet_discard_mac;
+        struct sshmac *packet_discard_mac;
 
         /* Used in packet_read_poll2() */
         u_int packlen;
@@ -198,121 +211,177 @@ struct session_state {
         /* Used in packet_set_maxsize */
         int set_maxsize_called;
 
-        TAILQ_HEAD(, packet) outgoing;
-};
+        /* One-off warning about weak ciphers */
+        int cipher_warning_done;
 
-static struct session_state *active_state, *backup_state;
+        /* SSH1 CRC compensation attack detector */
+        struct deattack_ctx deattack;
 
-static struct session_state *
-alloc_session_state(void)
-{
-        struct session_state *s = xcalloc(1, sizeof(*s));
+        TAILQ_HEAD(, packet) outgoing;
+};
 
-        s->connection_in = -1;
-        s->connection_out = -1;
-        s->max_packet_size = 32768;
-        s->packet_timeout_ms = -1;
-        return s;
+struct ssh *
+ssh_alloc_session_state(void)
+{
+        struct ssh *ssh = NULL;
+        struct session_state *state = NULL;
+
+        if ((ssh = calloc(1, sizeof(*ssh))) == NULL ||
+            (state = calloc(1, sizeof(*state))) == NULL ||
+            (state->input = sshbuf_new()) == NULL ||
+            (state->output = sshbuf_new()) == NULL ||
+            (state->outgoing_packet = sshbuf_new()) == NULL ||
+            (state->incoming_packet = sshbuf_new()) == NULL)
+                goto fail;
+        TAILQ_INIT(&state->outgoing);
+        TAILQ_INIT(&ssh->private_keys);
+        TAILQ_INIT(&ssh->public_keys);
+        state->connection_in = -1;
+        state->connection_out = -1;
+        state->max_packet_size = 32768;
+        state->packet_timeout_ms = -1;
+        state->p_send.packets = state->p_read.packets = 0;
+        state->initialized = 1;
+        /*
+         * ssh_packet_send2() needs to queue packets until
+         * we've done the initial key exchange.
+         */
+        state->rekeying = 1;
+        ssh->state = state;
+        return ssh;
+ fail:
+        if (state) {
+                sshbuf_free(state->input);
+                sshbuf_free(state->output);
+                sshbuf_free(state->incoming_packet);
+                sshbuf_free(state->outgoing_packet);
+                free(state);
+        }
+        free(ssh);
+        return NULL;
 }
 
 /*
  * Sets the descriptors used for communication.  Disables encryption until
  * packet_set_encryption_key is called.
  */
-void
-packet_set_connection(int fd_in, int fd_out)
+struct ssh *
+ssh_packet_set_connection(struct ssh *ssh, int fd_in, int fd_out)
 {
-        const Cipher *none = cipher_by_name("none");
+        struct session_state *state;
+        const struct sshcipher *none = cipher_by_name("none");
         int r;
 
-        if (none == NULL)
-                fatal("packet_set_connection: cannot load cipher 'none'");
-        if (active_state == NULL)
-                active_state = alloc_session_state();
-        active_state->connection_in = fd_in;
-        active_state->connection_out = fd_out;
-        if ((r = cipher_init(&active_state->send_context, none,
+        if (none == NULL) {
+                error("%s: cannot load cipher 'none'", __func__);
+                return NULL;
+        }
+        if (ssh == NULL)
+                ssh = ssh_alloc_session_state();
+        if (ssh == NULL) {
+                error("%s: cound not allocate state", __func__);
+                return NULL;
+        }
+        state = ssh->state;
+        state->connection_in = fd_in;
+        state->connection_out = fd_out;
+        if ((r = cipher_init(&state->send_context, none,
             (const u_char *)"", 0, NULL, 0, CIPHER_ENCRYPT)) != 0 ||
-            (r = cipher_init(&active_state->receive_context, none,
-            (const u_char *)"", 0, NULL, 0, CIPHER_DECRYPT)) != 0)
-                fatal("%s: cipher_init: %s", __func__, ssh_err(r));
-        active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
-        if (!active_state->initialized) {
-                active_state->initialized = 1;
-                buffer_init(&active_state->input);
-                buffer_init(&active_state->output);
-                buffer_init(&active_state->outgoing_packet);
-                buffer_init(&active_state->incoming_packet);
-                TAILQ_INIT(&active_state->outgoing);
-                active_state->p_send.packets = active_state->p_read.packets = 0;
+            (r = cipher_init(&state->receive_context, none,
+            (const u_char *)"", 0, NULL, 0, CIPHER_DECRYPT)) != 0) {
+                error("%s: cipher_init failed: %s", __func__, ssh_err(r));
+                return NULL;
         }
+        state->newkeys[MODE_IN] = state->newkeys[MODE_OUT] = NULL;
+        deattack_init(&state->deattack);
+        /*
+         * Cache the IP address of the remote connection for use in error
+         * messages that might be generated after the connection has closed.
+         */
+        (void)ssh_remote_ipaddr(ssh);
+        return ssh;
 }
 
 void
-packet_set_timeout(int timeout, int count)
+ssh_packet_set_timeout(struct ssh *ssh, int timeout, int count)
 {
+        struct session_state *state = ssh->state;
+
         if (timeout <= 0 || count <= 0) {
-                active_state->packet_timeout_ms = -1;
+                state->packet_timeout_ms = -1;
                 return;
         }
         if ((INT_MAX / 1000) / count < timeout)
-                active_state->packet_timeout_ms = INT_MAX;
+                state->packet_timeout_ms = INT_MAX;
         else
-                active_state->packet_timeout_ms = timeout * count * 1000;
+                state->packet_timeout_ms = timeout * count * 1000;
 }
 
-static void
-packet_stop_discard(void)
+int
+ssh_packet_stop_discard(struct ssh *ssh)
 {
-        if (active_state->packet_discard_mac) {
+        struct session_state *state = ssh->state;
+        int r;
+
+        if (state->packet_discard_mac) {
                 char buf[1024];
-                
+
                 memset(buf, 'a', sizeof(buf));
-                while (buffer_len(&active_state->incoming_packet) <
+                while (sshbuf_len(state->incoming_packet) <
                     PACKET_MAX_SIZE)
-                        buffer_append(&active_state->incoming_packet, buf,
-                            sizeof(buf));
-                (void) mac_compute(active_state->packet_discard_mac,
-                    active_state->p_read.seqnr,
-                    buffer_ptr(&active_state->incoming_packet),
-                    PACKET_MAX_SIZE);
-        }
-        logit("Finished discarding for %.200s", get_remote_ipaddr());
-        cleanup_exit(255);
+                        if ((r = sshbuf_put(state->incoming_packet, buf,
+                            sizeof(buf))) != 0)
+                                return r;
+                (void) mac_compute(state->packet_discard_mac,
+                    state->p_read.seqnr,
+                    sshbuf_ptr(state->incoming_packet), PACKET_MAX_SIZE,
+                    NULL, 0);
+        }
+        logit("Finished discarding for %.200s", ssh_remote_ipaddr(ssh));
+        return SSH_ERR_MAC_INVALID;
 }
 
-static void
-packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
+static int
+ssh_packet_start_discard(struct ssh *ssh, struct sshenc *enc,
+    struct sshmac *mac, u_int packet_length, u_int discard)
 {
-        if (enc == NULL || !cipher_is_cbc(enc->cipher) || (mac && mac->etm))
-                packet_disconnect("Packet corrupt");
+        struct session_state *state = ssh->state;
+        int r;
+
+        if (enc == NULL || !cipher_is_cbc(enc->cipher) || (mac && mac->etm)) {
+                if ((r = sshpkt_disconnect(ssh, "Packet corrupt")) != 0)
+                        return r;
+                return SSH_ERR_MAC_INVALID;
+        }
         if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
-                active_state->packet_discard_mac = mac;
-        if (buffer_len(&active_state->input) >= discard)
-                packet_stop_discard();
-        active_state->packet_discard = discard -
-            buffer_len(&active_state->input);
+                state->packet_discard_mac = mac;
+        if (sshbuf_len(state->input) >= discard &&
+           (r = ssh_packet_stop_discard(ssh)) != 0)
+                return r;
+        state->packet_discard = discard - sshbuf_len(state->input);
+        return 0;
 }
 
 /* Returns 1 if remote host is connected via socket, 0 if not. */
 
 int
-packet_connection_is_on_socket(void)
+ssh_packet_connection_is_on_socket(struct ssh *ssh)
 {
+        struct session_state *state = ssh->state;
         struct sockaddr_storage from, to;
         socklen_t fromlen, tolen;
 
         /* filedescriptors in and out are the same, so it's a socket */
-        if (active_state->connection_in == active_state->connection_out)
+        if (state->connection_in == state->connection_out)
                 return 1;
         fromlen = sizeof(from);
         memset(&from, 0, sizeof(from));
-        if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
+        if (getpeername(state->connection_in, (struct sockaddr *)&from,
             &fromlen) < 0)
                 return 0;
         tolen = sizeof(to);
         memset(&to, 0, sizeof(to));
-        if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
+        if (getpeername(state->connection_out, (struct sockaddr *)&to,
             &tolen) < 0)
                 return 0;
         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
@@ -322,127 +391,23 @@ packet_connection_is_on_socket(void)
         return 1;
 }
 
-/*
- * Exports an IV from the CipherContext required to export the key
- * state back from the unprivileged child to the privileged parent
- * process.
- */
-
-void
-packet_get_keyiv(int mode, u_char *iv, u_int len)
-{
-        CipherContext *cc;
-        int r;
-
-        if (mode == MODE_OUT)
-                cc = &active_state->send_context;
-        else
-                cc = &active_state->receive_context;
-
-        if ((r = cipher_get_keyiv(cc, iv, len)) != 0)
-                fatal("%s: cipher_get_keyiv: %s", __func__, ssh_err(r));
-}
-
-int
-packet_get_keycontext(int mode, u_char *dat)
-{
-        CipherContext *cc;
-
-        if (mode == MODE_OUT)
-                cc = &active_state->send_context;
-        else
-                cc = &active_state->receive_context;
-
-        return (cipher_get_keycontext(cc, dat));
-}
-
-void
-packet_set_keycontext(int mode, u_char *dat)
-{
-        CipherContext *cc;
-
-        if (mode == MODE_OUT)
-                cc = &active_state->send_context;
-        else
-                cc = &active_state->receive_context;
-
-        cipher_set_keycontext(cc, dat);
-}
-
-int
-packet_get_keyiv_len(int mode)
-{
-        CipherContext *cc;
-
-        if (mode == MODE_OUT)
-                cc = &active_state->send_context;
-        else
-                cc = &active_state->receive_context;
-
-        return (cipher_get_keyiv_len(cc));
-}
-
 void
-packet_set_iv(int mode, u_char *dat)
+ssh_packet_get_bytes(struct ssh *ssh, u_int64_t *ibytes, u_int64_t *obytes)
 {
-        CipherContext *cc;
-        int r;
-
-        if (mode == MODE_OUT)
-                cc = &active_state->send_context;
-        else
-                cc = &active_state->receive_context;
-
-        if ((r = cipher_set_keyiv(cc, dat)) != 0)
-                fatal("%s: cipher_set_keyiv: %s", __func__, ssh_err(r));
+        if (ibytes)
+                *ibytes = ssh->state->p_read.bytes;
+        if (obytes)
+                *obytes = ssh->state->p_send.bytes;
 }
 
 int
-packet_get_ssh1_cipher(void)
-{
-        return (cipher_get_number(active_state->receive_context.cipher));
-}
-
-void
-packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks,
-    u_int32_t *packets, u_int64_t *bytes)
-{
-        struct packet_state *state;
-
-        state = (mode == MODE_IN) ?
-            &active_state->p_read : &active_state->p_send;
-        if (seqnr)
-                *seqnr = state->seqnr;
-        if (blocks)
-                *blocks = state->blocks;
-        if (packets)
-                *packets = state->packets;
-        if (bytes)
-                *bytes = state->bytes;
-}
-
-void
-packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
-    u_int64_t bytes)
-{
-        struct packet_state *state;
-
-        state = (mode == MODE_IN) ?
-            &active_state->p_read : &active_state->p_send;
-        state->seqnr = seqnr;
-        state->blocks = blocks;
-        state->packets = packets;
-        state->bytes = bytes;
-}
-
-static int
-packet_connection_af(void)
+ssh_packet_connection_af(struct ssh *ssh)
 {
         struct sockaddr_storage to;
         socklen_t tolen = sizeof(to);
 
         memset(&to, 0, sizeof(to));
-        if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
+        if (getsockname(ssh->state->connection_out, (struct sockaddr *)&to,
             &tolen) < 0)
                 return 0;
 #ifdef IPV4_IN_IPV6
@@ -456,72 +421,125 @@ packet_connection_af(void)
 /* Sets the connection into non-blocking mode. */
 
 void
-packet_set_nonblocking(void)
+ssh_packet_set_nonblocking(struct ssh *ssh)
 {
         /* Set the socket into non-blocking mode. */
-        set_nonblock(active_state->connection_in);
+        set_nonblock(ssh->state->connection_in);
 
-        if (active_state->connection_out != active_state->connection_in)
-                set_nonblock(active_state->connection_out);
+        if (ssh->state->connection_out != ssh->state->connection_in)
+                set_nonblock(ssh->state->connection_out);
 }
 
 /* Returns the socket used for reading. */
 
 int
-packet_get_connection_in(void)
+ssh_packet_get_connection_in(struct ssh *ssh)
 {
-        return active_state->connection_in;
+        return ssh->state->connection_in;
 }
 
 /* Returns the descriptor used for writing. */
 
 int
-packet_get_connection_out(void)
+ssh_packet_get_connection_out(struct ssh *ssh)
+{
+        return ssh->state->connection_out;
+}
+
+/*
+ * Returns the IP-address of the remote host as a string.  The returned
+ * string must not be freed.
+ */
+
+const char *
+ssh_remote_ipaddr(struct ssh *ssh)
 {
-        return active_state->connection_out;
+        /* Check whether we have cached the ipaddr. */
+        if (ssh->remote_ipaddr == NULL)
+                ssh->remote_ipaddr = ssh_packet_connection_is_on_socket(ssh) ?
+                    get_peer_ipaddr(ssh->state->connection_in) :
+                    strdup("UNKNOWN");
+        if (ssh->remote_ipaddr == NULL)
+                return "UNKNOWN";
+        return ssh->remote_ipaddr;
 }
 
 /* Closes the connection and clears and frees internal data structures. */
 
 void
-packet_close(void)
+ssh_packet_close(struct ssh *ssh)
 {
-        if (!active_state->initialized)
+        struct session_state *state = ssh->state;
+        int r;
+        u_int mode;
+
+        if (!state->initialized)
                 return;
-        active_state->initialized = 0;
-        if (active_state->connection_in == active_state->connection_out) {
-                shutdown(active_state->connection_out, SHUT_RDWR);
-                close(active_state->connection_out);
+        state->initialized = 0;
+        if (state->connection_in == state->connection_out) {
+                shutdown(state->connection_out, SHUT_RDWR);
+                close(state->connection_out);
         } else {
-                close(active_state->connection_in);
-                close(active_state->connection_out);
+                close(state->connection_in);
+                close(state->connection_out);
         }
-        buffer_free(&active_state->input);
-        buffer_free(&active_state->output);
-        buffer_free(&active_state->outgoing_packet);
-        buffer_free(&active_state->incoming_packet);
-        if (active_state->compression_buffer_ready) {
-                buffer_free(&active_state->compression_buffer);
-                buffer_compress_uninit();
+        sshbuf_free(state->input);
+        sshbuf_free(state->output);
+        sshbuf_free(state->outgoing_packet);
+        sshbuf_free(state->incoming_packet);
+        for (mode = 0; mode < MODE_MAX; mode++)
+                kex_free_newkeys(state->newkeys[mode]);
+        if (state->compression_buffer) {
+                sshbuf_free(state->compression_buffer);
+                if (state->compression_out_started) {
+                        z_streamp stream = &state->compression_out_stream;
+                        debug("compress outgoing: "
+                            "raw data %llu, compressed %llu, factor %.2f",
+                                (unsigned long long)stream->total_in,
+                                (unsigned long long)stream->total_out,
+                                stream->total_in == 0 ? 0.0 :
+                                (double) stream->total_out / stream->total_in);
+                        if (state->compression_out_failures == 0)
+                                deflateEnd(stream);
+                }
+                if (state->compression_in_started) {
+                        z_streamp stream = &state->compression_out_stream;
+                        debug("compress incoming: "
+                            "raw data %llu, compressed %llu, factor %.2f",
+                            (unsigned long long)stream->total_out,
+                            (unsigned long long)stream->total_in,
+                            stream->total_out == 0 ? 0.0 :
+                            (double) stream->total_in / stream->total_out);
+                        if (state->compression_in_failures == 0)
+                                inflateEnd(stream);
+                }
         }
-        cipher_cleanup(&active_state->send_context);
-        cipher_cleanup(&active_state->receive_context);
+        if ((r = cipher_cleanup(&state->send_context)) != 0)
+                error("%s: cipher_cleanup failed: %s", __func__, ssh_err(r));
+        if ((r = cipher_cleanup(&state->receive_context)) != 0)
+                error("%s: cipher_cleanup failed: %s", __func__, ssh_err(r));
+        if (ssh->remote_ipaddr) {
+                free(ssh->remote_ipaddr);
+                ssh->remote_ipaddr = NULL;
+        }
+        free(ssh->state);
+        ssh->state = NULL;
 }
 
 /* Sets remote side protocol flags. */
 
 void
-packet_set_protocol_flags(u_int protocol_flags)
+ssh_packet_set_protocol_flags(struct ssh *ssh, u_int protocol_flags)
 {
-        active_state->remote_protocol_flags = protocol_flags;
+        ssh->state->remote_protocol_flags = protocol_flags;
 }
 
 /* Returns the remote protocol flags set earlier by the above function. */
 
 u_int
-packet_get_protocol_flags(void)
+ssh_packet_get_protocol_flags(struct ssh *ssh)
 {
-        return active_state->remote_protocol_flags;
+        return ssh->state->remote_protocol_flags;
 }
 
 /*
@@ -529,251 +547,403 @@ packet_get_protocol_flags(void)
  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
  */
 
-static void
-packet_init_compression(void)
+static int
+ssh_packet_init_compression(struct ssh *ssh)
 {
-        if (active_state->compression_buffer_ready == 1)
-                return;
-        active_state->compression_buffer_ready = 1;
-        buffer_init(&active_state->compression_buffer);
+        if (!ssh->state->compression_buffer &&
+           ((ssh->state->compression_buffer = sshbuf_new()) == NULL))
+                return SSH_ERR_ALLOC_FAIL;
+        return 0;
 }
 
-void
-packet_start_compression(int level)
-{
-        if (active_state->packet_compression && !compat20)
-                fatal("Compression already enabled.");
-        active_state->packet_compression = 1;
-        packet_init_compression();
-        buffer_compress_init_send(level);
-        buffer_compress_init_recv();
+static int
+start_compression_out(struct ssh *ssh, int level)
+{
+        if (level < 1 || level > 9)
+                return SSH_ERR_INVALID_ARGUMENT;
+        debug("Enabling compression at level %d.", level);
+        if (ssh->state->compression_out_started == 1)
+                deflateEnd(&ssh->state->compression_out_stream);
+        switch (deflateInit(&ssh->state->compression_out_stream, level)) {
+        case Z_OK:
+                ssh->state->compression_out_started = 1;
+                break;
+        case Z_MEM_ERROR:
+                return SSH_ERR_ALLOC_FAIL;
+        default:
+                return SSH_ERR_INTERNAL_ERROR;
+        }
+        return 0;
 }
 
-/*
- * Causes any further packets to be encrypted using the given key.  The same
- * key is used for both sending and reception.  However, both directions are
- * encrypted independently of each other.
- */
+static int
+start_compression_in(struct ssh *ssh)
+{
+        if (ssh->state->compression_in_started == 1)
+                inflateEnd(&ssh->state->compression_in_stream);
+        switch (inflateInit(&ssh->state->compression_in_stream)) {
+        case Z_OK:
+                ssh->state->compression_in_started = 1;
+                break;
+        case Z_MEM_ERROR:
+                return SSH_ERR_ALLOC_FAIL;
+        default:
+                return SSH_ERR_INTERNAL_ERROR;
+        }
+        return 0;
+}
 
-void
-packet_set_encryption_key(const u_char *key, u_int keylen, int number)
+int
+ssh_packet_start_compression(struct ssh *ssh, int level)
 {
-        const Cipher *cipher = cipher_by_number(number);
         int r;
 
-        if (cipher == NULL)
-                fatal("packet_set_encryption_key: unknown cipher number %d", number);
-        if (keylen < 20)
-                fatal("packet_set_encryption_key: keylen too small: %d", keylen);
-        if (keylen > SSH_SESSION_KEY_LENGTH)
-                fatal("packet_set_encryption_key: keylen too big: %d", keylen);
-        memcpy(active_state->ssh1_key, key, keylen);
-        active_state->ssh1_keylen = keylen;
-        if ((r = cipher_init(&active_state->send_context, cipher,
-            key, keylen, NULL, 0, CIPHER_ENCRYPT)) != 0 ||
-            (r = cipher_init(&active_state->receive_context, cipher,
-            key, keylen, NULL, 0, CIPHER_DECRYPT)) != 0)
-                fatal("%s: cipher_init: %s", __func__, ssh_err(r));
+        if (ssh->state->packet_compression && !compat20)
+                return SSH_ERR_INTERNAL_ERROR;
+        ssh->state->packet_compression = 1;
+        if ((r = ssh_packet_init_compression(ssh)) != 0 ||
+            (r = start_compression_in(ssh)) != 0 ||
+            (r = start_compression_out(ssh, level)) != 0)
+                return r;
+        return 0;
 }
 
-u_int
-packet_get_encryption_key(u_char *key)
+/* XXX remove need for separate compression buffer */
+static int
+compress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
 {
-        if (key == NULL)
-                return (active_state->ssh1_keylen);
-        memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
-        return (active_state->ssh1_keylen);
-}
+        u_char buf[4096];
+        int r, status;
 
-/* Start constructing a packet to send. */
-void
-packet_start(u_char type)
-{
-        u_char buf[9];
-        int len;
+        if (ssh->state->compression_out_started != 1)
+                return SSH_ERR_INTERNAL_ERROR;
 
-        DBG(debug("packet_start[%d]", type));
-        len = compat20 ? 6 : 9;
-        memset(buf, 0, len - 1);
-        buf[len - 1] = type;
-        buffer_clear(&active_state->outgoing_packet);
-        buffer_append(&active_state->outgoing_packet, buf, len);
+        /* This case is not handled below. */
+        if (sshbuf_len(in) == 0)
+                return 0;
+
+        /* Input is the contents of the input buffer. */
+        if ((ssh->state->compression_out_stream.next_in =
+            sshbuf_mutable_ptr(in)) == NULL)
+                return SSH_ERR_INTERNAL_ERROR;
+        ssh->state->compression_out_stream.avail_in = sshbuf_len(in);
+
+        /* Loop compressing until deflate() returns with avail_out != 0. */
+        do {
+                /* Set up fixed-size output buffer. */
+                ssh->state->compression_out_stream.next_out = buf;
+                ssh->state->compression_out_stream.avail_out = sizeof(buf);
+
+                /* Compress as much data into the buffer as possible. */
+                status = deflate(&ssh->state->compression_out_stream,
+                    Z_PARTIAL_FLUSH);
+                switch (status) {
+                case Z_MEM_ERROR:
+                        return SSH_ERR_ALLOC_FAIL;
+                case Z_OK:
+                        /* Append compressed data to output_buffer. */
+                        if ((r = sshbuf_put(out, buf, sizeof(buf) -
+                            ssh->state->compression_out_stream.avail_out)) != 0)
+                                return r;
+                        break;
+                case Z_STREAM_ERROR:
+                default:
+                        ssh->state->compression_out_failures++;
+                        return SSH_ERR_INVALID_FORMAT;
+                }
+        } while (ssh->state->compression_out_stream.avail_out == 0);
+        return 0;
 }
 
-/* Append payload. */
-void
-packet_put_char(int value)
+static int
+uncompress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
 {
-        char ch = value;
+        u_char buf[4096];
+        int r, status;
 
-        buffer_append(&active_state->outgoing_packet, &ch, 1);
-}
+        if (ssh->state->compression_in_started != 1)
+                return SSH_ERR_INTERNAL_ERROR;
 
-void
-packet_put_int(u_int value)
-{
-        buffer_put_int(&active_state->outgoing_packet, value);
-}
+        if ((ssh->state->compression_in_stream.next_in =
+            sshbuf_mutable_ptr(in)) == NULL)
+                return SSH_ERR_INTERNAL_ERROR;
+        ssh->state->compression_in_stream.avail_in = sshbuf_len(in);
 
-void
-packet_put_int64(u_int64_t value)
-{
-        buffer_put_int64(&active_state->outgoing_packet, value);
+        for (;;) {
+                /* Set up fixed-size output buffer. */
+                ssh->state->compression_in_stream.next_out = buf;
+                ssh->state->compression_in_stream.avail_out = sizeof(buf);
+
+                status = inflate(&ssh->state->compression_in_stream,
+                    Z_PARTIAL_FLUSH);
+                switch (status) {
+                case Z_OK:
+                        if ((r = sshbuf_put(out, buf, sizeof(buf) -
+                            ssh->state->compression_in_stream.avail_out)) != 0)
+                                return r;
+                        break;
+                case Z_BUF_ERROR:
+                        /*
+                         * Comments in zlib.h say that we should keep calling
+                         * inflate() until we get an error.  This appears to
+                         * be the error that we get.
+                         */
+                        return 0;
+                case Z_DATA_ERROR:
+                        return SSH_ERR_INVALID_FORMAT;
+                case Z_MEM_ERROR:
+                        return SSH_ERR_ALLOC_FAIL;
+                case Z_STREAM_ERROR:
+                default:
+                        ssh->state->compression_in_failures++;
+                        return SSH_ERR_INTERNAL_ERROR;
+                }
+        }
+        /* NOTREACHED */
 }
 
-void
-packet_put_string(const void *buf, u_int len)
+/* Serialise compression state into a blob for privsep */
+static int
+ssh_packet_get_compress_state(struct sshbuf *m, struct ssh *ssh)
 {
-        buffer_put_string(&active_state->outgoing_packet, buf, len);
-}
+        struct session_state *state = ssh->state;
+        struct sshbuf *b;
+        int r;
 
-void
-packet_put_cstring(const char *str)
+        if ((b = sshbuf_new()) == NULL)
+                return SSH_ERR_ALLOC_FAIL;
+        if (state->compression_in_started) {
+                if ((r = sshbuf_put_string(b, &state->compression_in_stream,
+                    sizeof(state->compression_in_stream))) != 0)
+                        goto out;
+        } else if ((r = sshbuf_put_string(b, NULL, 0)) != 0)
+                goto out;
+        if (state->compression_out_started) {
+                if ((r = sshbuf_put_string(b, &state->compression_out_stream,
+                    sizeof(state->compression_out_stream))) != 0)
+                        goto out;
+        } else if ((r = sshbuf_put_string(b, NULL, 0)) != 0)
+                goto out;
+        r = sshbuf_put_stringb(m, b);
+ out:
+        sshbuf_free(b);
+        return r;
+}
+
+/* Deserialise compression state from a blob for privsep */
+static int
+ssh_packet_set_compress_state(struct ssh *ssh, struct sshbuf *m)
 {
-        buffer_put_cstring(&active_state->outgoing_packet, str);
+        struct session_state *state = ssh->state;
+        struct sshbuf *b = NULL;
+        int r;
+        const u_char *inblob, *outblob;
+        size_t inl, outl;
+
+        if ((r = sshbuf_froms(m, &b)) != 0)
+                goto out;
+        if ((r = sshbuf_get_string_direct(b, &inblob, &inl)) != 0 ||
+            (r = sshbuf_get_string_direct(b, &outblob, &outl)) != 0)
+                goto out;
+        if (inl == 0)
+                state->compression_in_started = 0;
+        else if (inl != sizeof(state->compression_in_stream)) {
+                r = SSH_ERR_INTERNAL_ERROR;
+                goto out;
+        } else {
+                state->compression_in_started = 1;
+                memcpy(&state->compression_in_stream, inblob, inl);
+        }
+        if (outl == 0)
+                state->compression_out_started = 0;
+        else if (outl != sizeof(state->compression_out_stream)) {
+                r = SSH_ERR_INTERNAL_ERROR;
+                goto out;
+        } else {
+                state->compression_out_started = 1;
+                memcpy(&state->compression_out_stream, outblob, outl);
+        }
+        r = 0;
+ out:
+        sshbuf_free(b);
+        return r;
 }
 
 void
-packet_put_raw(const void *buf, u_int len)
+ssh_packet_set_compress_hooks(struct ssh *ssh, void *ctx,
+    void *(*allocfunc)(void *, u_int, u_int),
+    void (*freefunc)(void *, void *))
 {
-        buffer_append(&active_state->outgoing_packet, buf, len);
+        ssh->state->compression_out_stream.zalloc = (alloc_func)allocfunc;
+        ssh->state->compression_out_stream.zfree = (free_func)freefunc;
+        ssh->state->compression_out_stream.opaque = ctx;
+        ssh->state->compression_in_stream.zalloc = (alloc_func)allocfunc;
+        ssh->state->compression_in_stream.zfree = (free_func)freefunc;
+        ssh->state->compression_in_stream.opaque = ctx;
 }
 
-#ifdef WITH_OPENSSL
-void
-packet_put_bignum(BIGNUM * value)
-{
-        buffer_put_bignum(&active_state->outgoing_packet, value);
-}
+/*
+ * Causes any further packets to be encrypted using the given key.  The same
+ * key is used for both sending and reception.  However, both directions are
+ * encrypted independently of each other.
+ */
 
 void
-packet_put_bignum2(BIGNUM * value)
+ssh_packet_set_encryption_key(struct ssh *ssh, const u_char *key, u_int keylen, int number)
 {
-        buffer_put_bignum2(&active_state->outgoing_packet, value);
-}
-#endif
+#ifdef WITH_SSH1
+        struct session_state *state = ssh->state;
+        const struct sshcipher *cipher = cipher_by_number(number);
+        int r;
+        const char *wmsg;
 
-#ifdef OPENSSL_HAS_ECC
-void
-packet_put_ecpoint(const EC_GROUP *curve, const EC_POINT *point)
-{
-        buffer_put_ecpoint(&active_state->outgoing_packet, curve, point);
+        if (cipher == NULL)
+                fatal("%s: unknown cipher number %d", __func__, number);
+        if (keylen < 20)
+                fatal("%s: keylen too small: %d", __func__, keylen);
+        if (keylen > SSH_SESSION_KEY_LENGTH)
+                fatal("%s: keylen too big: %d", __func__, keylen);
+        memcpy(state->ssh1_key, key, keylen);
+        state->ssh1_keylen = keylen;
+        if ((r = cipher_init(&state->send_context, cipher, key, keylen,
+            NULL, 0, CIPHER_ENCRYPT)) != 0 ||
+            (r = cipher_init(&state->receive_context, cipher, key, keylen,
+            NULL, 0, CIPHER_DECRYPT) != 0))
+                fatal("%s: cipher_init failed: %s", __func__, ssh_err(r));
+        if (!state->cipher_warning_done &&
+            ((wmsg = cipher_warning_message(&state->send_context)) != NULL ||
+            (wmsg = cipher_warning_message(&state->send_context)) != NULL)) {
+                error("Warning: %s", wmsg);
+                state->cipher_warning_done = 1;
+        }
+#endif /* WITH_SSH1 */
 }
-#endif
 
 /*
  * Finalizes and sends the packet.  If the encryption key has been set,
  * encrypts the packet before sending.
  */
 
-static void
-packet_send1(void)
+int
+ssh_packet_send1(struct ssh *ssh)
 {
+        struct session_state *state = ssh->state;
         u_char buf[8], *cp;
-        int i, padding, len;
+        int r, padding, len;
         u_int checksum;
-        u_int32_t rnd = 0;
 
         /*
          * If using packet compression, compress the payload of the outgoing
          * packet.
          */
-        if (active_state->packet_compression) {
-                buffer_clear(&active_state->compression_buffer);
+        if (state->packet_compression) {
+                sshbuf_reset(state->compression_buffer);
                 /* Skip padding. */
-                buffer_consume(&active_state->outgoing_packet, 8);
+                if ((r = sshbuf_consume(state->outgoing_packet, 8)) != 0)
+                        goto out;
                 /* padding */
-                buffer_append(&active_state->compression_buffer,
-                    "\0\0\0\0\0\0\0\0", 8);
-                buffer_compress(&active_state->outgoing_packet,
-                    &active_state->compression_buffer);
-                buffer_clear(&active_state->outgoing_packet);
-                buffer_append(&active_state->outgoing_packet,
-                    buffer_ptr(&active_state->compression_buffer),
-                    buffer_len(&active_state->compression_buffer));
+                if ((r = sshbuf_put(state->compression_buffer,
+                    "\0\0\0\0\0\0\0\0", 8)) != 0)
+                        goto out;
+                if ((r = compress_buffer(ssh, state->outgoing_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
+                sshbuf_reset(state->outgoing_packet);
+                if ((r = sshbuf_putb(state->outgoing_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
         }
         /* Compute packet length without padding (add checksum, remove padding). */
-        len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
+        len = sshbuf_len(state->outgoing_packet) + 4 - 8;
 
         /* Insert padding. Initialized to zero in packet_start1() */
         padding = 8 - len % 8;
-        if (!active_state->send_context.plaintext) {
-                cp = buffer_ptr(&active_state->outgoing_packet);
-                for (i = 0; i < padding; i++) {
-                        if (i % 4 == 0)
-                                rnd = arc4random();
-                        cp[7 - i] = rnd & 0xff;
-                        rnd >>= 8;
+        if (!state->send_context.plaintext) {
+                cp = sshbuf_mutable_ptr(state->outgoing_packet);
+                if (cp == NULL) {
+                        r = SSH_ERR_INTERNAL_ERROR;
+                        goto out;
                 }
+                arc4random_buf(cp + 8 - padding, padding);
         }
-        buffer_consume(&active_state->outgoing_packet, 8 - padding);
+        if ((r = sshbuf_consume(state->outgoing_packet, 8 - padding)) != 0)
+                goto out;
 
         /* Add check bytes. */
-        checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
-            buffer_len(&active_state->outgoing_packet));
-        put_u32(buf, checksum);
-        buffer_append(&active_state->outgoing_packet, buf, 4);
+        checksum = ssh_crc32(sshbuf_ptr(state->outgoing_packet),
+            sshbuf_len(state->outgoing_packet));
+        POKE_U32(buf, checksum);
+        if ((r = sshbuf_put(state->outgoing_packet, buf, 4)) != 0)
+                goto out;
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "packet_send plain: ");
-        buffer_dump(&active_state->outgoing_packet);
+        sshbuf_dump(state->outgoing_packet, stderr);
 #endif
 
         /* Append to output. */
-        put_u32(buf, len);
-        buffer_append(&active_state->output, buf, 4);
-        cp = buffer_append_space(&active_state->output,
-            buffer_len(&active_state->outgoing_packet));
-        if (cipher_crypt(&active_state->send_context, 0, cp,
-            buffer_ptr(&active_state->outgoing_packet),
-            buffer_len(&active_state->outgoing_packet), 0, 0) != 0)
-                fatal("%s: cipher_crypt failed", __func__);
+        POKE_U32(buf, len);
+        if ((r = sshbuf_put(state->output, buf, 4)) != 0)
+                goto out;
+        if ((r = sshbuf_reserve(state->output,
+            sshbuf_len(state->outgoing_packet), &cp)) != 0)
+                goto out;
+        if ((r = cipher_crypt(&state->send_context, 0, cp,
+            sshbuf_ptr(state->outgoing_packet),
+            sshbuf_len(state->outgoing_packet), 0, 0)) != 0)
+                goto out;
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "encrypted: ");
-        buffer_dump(&active_state->output);
+        sshbuf_dump(state->output, stderr);
 #endif
-        active_state->p_send.packets++;
-        active_state->p_send.bytes += len +
-            buffer_len(&active_state->outgoing_packet);
-        buffer_clear(&active_state->outgoing_packet);
+        state->p_send.packets++;
+        state->p_send.bytes += len +
+            sshbuf_len(state->outgoing_packet);
+        sshbuf_reset(state->outgoing_packet);
 
         /*
          * Note that the packet is now only buffered in output.  It won't be
-         * actually sent until packet_write_wait or packet_write_poll is
-         * called.
+         * actually sent until ssh_packet_write_wait or ssh_packet_write_poll
+         * is called.
          */
+        r = 0;
+ out:
+        return r;
 }
 
-void
-set_newkeys(int mode)
+int
+ssh_set_newkeys(struct ssh *ssh, int mode)
 {
-        Enc *enc;
-        Mac *mac;
-        Comp *comp;
-        CipherContext *cc;
+        struct session_state *state = ssh->state;
+        struct sshenc *enc;
+        struct sshmac *mac;
+        struct sshcomp *comp;
+        struct sshcipher_ctx *cc;
         u_int64_t *max_blocks;
+        const char *wmsg;
         int r, crypt_type;
 
         debug2("set_newkeys: mode %d", mode);
 
         if (mode == MODE_OUT) {
-                cc = &active_state->send_context;
+                cc = &state->send_context;
                 crypt_type = CIPHER_ENCRYPT;
-                active_state->p_send.packets = active_state->p_send.blocks = 0;
-                max_blocks = &active_state->max_blocks_out;
+                state->p_send.packets = state->p_send.blocks = 0;
+                max_blocks = &state->max_blocks_out;
         } else {
-                cc = &active_state->receive_context;
+                cc = &state->receive_context;
                 crypt_type = CIPHER_DECRYPT;
-                active_state->p_read.packets = active_state->p_read.blocks = 0;
-                max_blocks = &active_state->max_blocks_in;
+                state->p_read.packets = state->p_read.blocks = 0;
+                max_blocks = &state->max_blocks_in;
         }
-        if (active_state->newkeys[mode] != NULL) {
+        if (state->newkeys[mode] != NULL) {
                 debug("set_newkeys: rekeying");
-                cipher_cleanup(cc);
-                enc  = &active_state->newkeys[mode]->enc;
-                mac  = &active_state->newkeys[mode]->mac;
-                comp = &active_state->newkeys[mode]->comp;
+                if ((r = cipher_cleanup(cc)) != 0)
+                        return r;
+                enc  = &state->newkeys[mode]->enc;
+                mac  = &state->newkeys[mode]->mac;
+                comp = &state->newkeys[mode]->comp;
                 mac_clear(mac);
                 explicit_bzero(enc->iv,  enc->iv_len);
                 explicit_bzero(enc->key, enc->key_len);
@@ -784,32 +954,45 @@ set_newkeys(int mode)
                 free(mac->name);
                 free(mac->key);
                 free(comp->name);
-                free(active_state->newkeys[mode]);
-        }
-        active_state->newkeys[mode] = kex_get_newkeys(mode);
-        if (active_state->newkeys[mode] == NULL)
-                fatal("newkeys: no keys for mode %d", mode);
-        enc  = &active_state->newkeys[mode]->enc;
-        mac  = &active_state->newkeys[mode]->mac;
-        comp = &active_state->newkeys[mode]->comp;
-        if (cipher_authlen(enc->cipher) == 0 && mac_init(mac) == 0)
-                mac->enabled = 1;
+                free(state->newkeys[mode]);
+        }
+        /* move newkeys from kex to state */
+        if ((state->newkeys[mode] = ssh->kex->newkeys[mode]) == NULL)
+                return SSH_ERR_INTERNAL_ERROR;
+        ssh->kex->newkeys[mode] = NULL;
+        enc  = &state->newkeys[mode]->enc;
+        mac  = &state->newkeys[mode]->mac;
+        comp = &state->newkeys[mode]->comp;
+        if (cipher_authlen(enc->cipher) == 0) {
+                if ((r = mac_init(mac)) != 0)
+                        return r;
+        }
+        mac->enabled = 1;
         DBG(debug("cipher_init_context: %d", mode));
         if ((r = cipher_init(cc, enc->cipher, enc->key, enc->key_len,
             enc->iv, enc->iv_len, crypt_type)) != 0)
-                fatal("%s: cipher_init: %s", __func__, ssh_err(r));
+                return r;
+        if (!state->cipher_warning_done &&
+            (wmsg = cipher_warning_message(cc)) != NULL) {
+                error("Warning: %s", wmsg);
+                state->cipher_warning_done = 1;
+        }
         /* Deleting the keys does not gain extra security */
         /* explicit_bzero(enc->iv,  enc->block_size);
            explicit_bzero(enc->key, enc->key_len);
            explicit_bzero(mac->key, mac->key_len); */
         if ((comp->type == COMP_ZLIB ||
             (comp->type == COMP_DELAYED &&
-             active_state->after_authentication)) && comp->enabled == 0) {
-                packet_init_compression();
-                if (mode == MODE_OUT)
-                        buffer_compress_init_send(6);
-                else
-                        buffer_compress_init_recv();
+             state->after_authentication)) && comp->enabled == 0) {
+                if ((r = ssh_packet_init_compression(ssh)) < 0)
+                        return r;
+                if (mode == MODE_OUT) {
+                        if ((r = start_compression_out(ssh, 6)) != 0)
+                                return r;
+                } else {
+                        if ((r = start_compression_in(ssh)) != 0)
+                                return r;
+                }
                 comp->enabled = 1;
         }
         /*
@@ -820,9 +1003,10 @@ set_newkeys(int mode)
                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
         else
                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
-        if (active_state->rekey_limit)
+        if (state->rekey_limit)
                 *max_blocks = MIN(*max_blocks,
-                    active_state->rekey_limit / enc->block_size);
+                    state->rekey_limit / enc->block_size);
+        return 0;
 }
 
 /*
@@ -830,52 +1014,59 @@ set_newkeys(int mode)
  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
  */
-static void
-packet_enable_delayed_compress(void)
+static int
+ssh_packet_enable_delayed_compress(struct ssh *ssh)
 {
-        Comp *comp = NULL;
-        int mode;
+        struct session_state *state = ssh->state;
+        struct sshcomp *comp = NULL;
+        int r, mode;
 
         /*
          * Remember that we are past the authentication step, so rekeying
          * with COMP_DELAYED will turn on compression immediately.
          */
-        active_state->after_authentication = 1;
+        state->after_authentication = 1;
         for (mode = 0; mode < MODE_MAX; mode++) {
                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
-                if (active_state->newkeys[mode] == NULL)
+                if (state->newkeys[mode] == NULL)
                         continue;
-                comp = &active_state->newkeys[mode]->comp;
+                comp = &state->newkeys[mode]->comp;
                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
-                        packet_init_compression();
-                        if (mode == MODE_OUT)
-                                buffer_compress_init_send(6);
-                        else
-                                buffer_compress_init_recv();
+                        if ((r = ssh_packet_init_compression(ssh)) != 0)
+                                return r;
+                        if (mode == MODE_OUT) {
+                                if ((r = start_compression_out(ssh, 6)) != 0)
+                                        return r;
+                        } else {
+                                if ((r = start_compression_in(ssh)) != 0)
+                                        return r;
+                        }
                         comp->enabled = 1;
                 }
         }
+        return 0;
 }
 
 /*
  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
  */
-static void
-packet_send2_wrapped(void)
+int
+ssh_packet_send2_wrapped(struct ssh *ssh)
 {
-        u_char type, *cp, *macbuf = NULL;
+        struct session_state *state = ssh->state;
+        u_char type, *cp, macbuf[SSH_DIGEST_MAX_LENGTH];
         u_char padlen, pad = 0;
-        u_int i, len, authlen = 0, aadlen = 0;
-        u_int32_t rnd = 0;
-        Enc *enc   = NULL;
-        Mac *mac   = NULL;
-        Comp *comp = NULL;
-        int block_size;
-
-        if (active_state->newkeys[MODE_OUT] != NULL) {
-                enc  = &active_state->newkeys[MODE_OUT]->enc;
-                mac  = &active_state->newkeys[MODE_OUT]->mac;
-                comp = &active_state->newkeys[MODE_OUT]->comp;
+        u_int authlen = 0, aadlen = 0;
+        u_int len;
+        struct sshenc *enc   = NULL;
+        struct sshmac *mac   = NULL;
+        struct sshcomp *comp = NULL;
+        int r, block_size;
+
+        if (state->newkeys[MODE_OUT] != NULL) {
+                enc  = &state->newkeys[MODE_OUT]->enc;
+                mac  = &state->newkeys[MODE_OUT]->mac;
+                comp = &state->newkeys[MODE_OUT]->comp;
                 /* disable mac for authenticated encryption */
                 if ((authlen = cipher_authlen(enc->cipher)) != 0)
                         mac = NULL;
@@ -883,32 +1074,34 @@ packet_send2_wrapped(void)
         block_size = enc ? enc->block_size : 8;
         aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
 
-        cp = buffer_ptr(&active_state->outgoing_packet);
-        type = cp[5];
+        type = (sshbuf_ptr(state->outgoing_packet))[5];
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "plain:     ");
-        buffer_dump(&active_state->outgoing_packet);
+        sshbuf_dump(state->outgoing_packet, stderr);
 #endif
 
         if (comp && comp->enabled) {
-                len = buffer_len(&active_state->outgoing_packet);
+                len = sshbuf_len(state->outgoing_packet);
                 /* skip header, compress only payload */
-                buffer_consume(&active_state->outgoing_packet, 5);
-                buffer_clear(&active_state->compression_buffer);
-                buffer_compress(&active_state->outgoing_packet,
-                    &active_state->compression_buffer);
-                buffer_clear(&active_state->outgoing_packet);
-                buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
-                buffer_append(&active_state->outgoing_packet,
-                    buffer_ptr(&active_state->compression_buffer),
-                    buffer_len(&active_state->compression_buffer));
-                DBG(debug("compression: raw %d compressed %d", len,
-                    buffer_len(&active_state->outgoing_packet)));
+                if ((r = sshbuf_consume(state->outgoing_packet, 5)) != 0)
+                        goto out;
+                sshbuf_reset(state->compression_buffer);
+                if ((r = compress_buffer(ssh, state->outgoing_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
+                sshbuf_reset(state->outgoing_packet);
+                if ((r = sshbuf_put(state->outgoing_packet,
+                    "\0\0\0\0\0", 5)) != 0 ||
+                    (r = sshbuf_putb(state->outgoing_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
+                DBG(debug("compression: raw %d compressed %zd", len,
+                    sshbuf_len(state->outgoing_packet)));
         }
 
         /* sizeof (packet_len + pad_len + payload) */
-        len = buffer_len(&active_state->outgoing_packet);
+        len = sshbuf_len(state->outgoing_packet);
 
         /*
          * calc size of padding, alloc space, get random data,
@@ -918,139 +1111,145 @@ packet_send2_wrapped(void)
         padlen = block_size - (len % block_size);
         if (padlen < 4)
                 padlen += block_size;
-        if (active_state->extra_pad) {
+        if (state->extra_pad) {
                 /* will wrap if extra_pad+padlen > 255 */
-                active_state->extra_pad =
-                    roundup(active_state->extra_pad, block_size);
-                pad = active_state->extra_pad -
-                    ((len + padlen) % active_state->extra_pad);
+                state->extra_pad =
+                    roundup(state->extra_pad, block_size);
+                pad = state->extra_pad -
+                    ((len + padlen) % state->extra_pad);
                 DBG(debug3("%s: adding %d (len %d padlen %d extra_pad %d)",
-                    __func__, pad, len, padlen, active_state->extra_pad));
+                    __func__, pad, len, padlen, state->extra_pad));
                 padlen += pad;
-                active_state->extra_pad = 0;
+                state->extra_pad = 0;
         }
-        cp = buffer_append_space(&active_state->outgoing_packet, padlen);
-        if (enc && !active_state->send_context.plaintext) {
+        if ((r = sshbuf_reserve(state->outgoing_packet, padlen, &cp)) != 0)
+                goto out;
+        if (enc && !state->send_context.plaintext) {
                 /* random padding */
-                for (i = 0; i < padlen; i++) {
-                        if (i % 4 == 0)
-                                rnd = arc4random();
-                        cp[i] = rnd & 0xff;
-                        rnd >>= 8;
-                }
+                arc4random_buf(cp, padlen);
         } else {
                 /* clear padding */
                 explicit_bzero(cp, padlen);
         }
         /* sizeof (packet_len + pad_len + payload + padding) */
-        len = buffer_len(&active_state->outgoing_packet);
-        cp = buffer_ptr(&active_state->outgoing_packet);
+        len = sshbuf_len(state->outgoing_packet);
+        cp = sshbuf_mutable_ptr(state->outgoing_packet);
+        if (cp == NULL) {
+                r = SSH_ERR_INTERNAL_ERROR;
+                goto out;
+        }
         /* packet_length includes payload, padding and padding length field */
-        put_u32(cp, len - 4);
+        POKE_U32(cp, len - 4);
         cp[4] = padlen;
         DBG(debug("send: len %d (includes padlen %d, aadlen %d)",
             len, padlen, aadlen));
 
         /* compute MAC over seqnr and packet(length fields, payload, padding) */
         if (mac && mac->enabled && !mac->etm) {
-                macbuf = mac_compute(mac, active_state->p_send.seqnr,
-                    buffer_ptr(&active_state->outgoing_packet), len);
-                DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
+                if ((r = mac_compute(mac, state->p_send.seqnr,
+                    sshbuf_ptr(state->outgoing_packet), len,
+                    macbuf, sizeof(macbuf))) != 0)
+                        goto out;
+                DBG(debug("done calc MAC out #%d", state->p_send.seqnr));
         }
         /* encrypt packet and append to output buffer. */
-        cp = buffer_append_space(&active_state->output, len + authlen);
-        if (cipher_crypt(&active_state->send_context, active_state->p_send.seqnr,
-            cp, buffer_ptr(&active_state->outgoing_packet),
-            len - aadlen, aadlen, authlen) != 0)
-                fatal("%s: cipher_crypt failed", __func__);
+        if ((r = sshbuf_reserve(state->output,
+            sshbuf_len(state->outgoing_packet) + authlen, &cp)) != 0)
+                goto out;
+        if ((r = cipher_crypt(&state->send_context, state->p_send.seqnr, cp,
+            sshbuf_ptr(state->outgoing_packet),
+            len - aadlen, aadlen, authlen)) != 0)
+                goto out;
         /* append unencrypted MAC */
         if (mac && mac->enabled) {
                 if (mac->etm) {
                         /* EtM: compute mac over aadlen + cipher text */
-                        macbuf = mac_compute(mac,
-                            active_state->p_send.seqnr, cp, len);
+                        if ((r = mac_compute(mac, state->p_send.seqnr,
+                            cp, len, macbuf, sizeof(macbuf))) != 0)
+                                goto out;
                         DBG(debug("done calc MAC(EtM) out #%d",
-                            active_state->p_send.seqnr));
+                            state->p_send.seqnr));
                 }
-                buffer_append(&active_state->output, macbuf, mac->mac_len);
+                if ((r = sshbuf_put(state->output, macbuf, mac->mac_len)) != 0)
+                        goto out;
         }
 #ifdef PACKET_DEBUG
         fprintf(stderr, "encrypted: ");
-        buffer_dump(&active_state->output);
+        sshbuf_dump(state->output, stderr);
 #endif
         /* increment sequence number for outgoing packets */
-        if (++active_state->p_send.seqnr == 0)
+        if (++state->p_send.seqnr == 0)
                 logit("outgoing seqnr wraps around");
-        if (++active_state->p_send.packets == 0)
-                if (!(datafellows & SSH_BUG_NOREKEY))
-                        fatal("XXX too many packets with same key");
-        active_state->p_send.blocks += len / block_size;
-        active_state->p_send.bytes += len;
-        buffer_clear(&active_state->outgoing_packet);
+        if (++state->p_send.packets == 0)
+                if (!(ssh->compat & SSH_BUG_NOREKEY))
+                        return SSH_ERR_NEED_REKEY;
+        state->p_send.blocks += len / block_size;
+        state->p_send.bytes += len;
+        sshbuf_reset(state->outgoing_packet);
 
         if (type == SSH2_MSG_NEWKEYS)
-                set_newkeys(MODE_OUT);
-        else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
-                packet_enable_delayed_compress();
+                r = ssh_set_newkeys(ssh, MODE_OUT);
+        else if (type == SSH2_MSG_USERAUTH_SUCCESS && state->server_side)
+                r = ssh_packet_enable_delayed_compress(ssh);
+        else
+                r = 0;
+ out:
+        return r;
 }
 
-static void
-packet_send2(void)
+int
+ssh_packet_send2(struct ssh *ssh)
 {
+        struct session_state *state = ssh->state;
         struct packet *p;
-        u_char type, *cp;
+        u_char type;
+        int r;
 
-        cp = buffer_ptr(&active_state->outgoing_packet);
-        type = cp[5];
+        type = sshbuf_ptr(state->outgoing_packet)[5];
 
         /* during rekeying we can only send key exchange messages */
-        if (active_state->rekeying) {
+        if (state->rekeying) {
                 if ((type < SSH2_MSG_TRANSPORT_MIN) ||
                     (type > SSH2_MSG_TRANSPORT_MAX) ||
                     (type == SSH2_MSG_SERVICE_REQUEST) ||
                     (type == SSH2_MSG_SERVICE_ACCEPT)) {
                         debug("enqueue packet: %u", type);
-                        p = xcalloc(1, sizeof(*p));
+                        p = calloc(1, sizeof(*p));
+                        if (p == NULL)
+                                return SSH_ERR_ALLOC_FAIL;
                         p->type = type;
-                        memcpy(&p->payload, &active_state->outgoing_packet,
-                            sizeof(Buffer));
-                        buffer_init(&active_state->outgoing_packet);
-                        TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
-                        return;
+                        p->payload = state->outgoing_packet;
+                        TAILQ_INSERT_TAIL(&state->outgoing, p, next);
+                        state->outgoing_packet = sshbuf_new();
+                        if (state->outgoing_packet == NULL)
+                                return SSH_ERR_ALLOC_FAIL;
+                        return 0;
                 }
         }
 
         /* rekeying starts with sending KEXINIT */
         if (type == SSH2_MSG_KEXINIT)
-                active_state->rekeying = 1;
+                state->rekeying = 1;
 
-        packet_send2_wrapped();
+        if ((r = ssh_packet_send2_wrapped(ssh)) != 0)
+                return r;
 
         /* after a NEWKEYS message we can send the complete queue */
         if (type == SSH2_MSG_NEWKEYS) {
-                active_state->rekeying = 0;
-                active_state->rekey_time = monotime();
-                while ((p = TAILQ_FIRST(&active_state->outgoing))) {
+                state->rekeying = 0;
+                state->rekey_time = monotime();
+                while ((p = TAILQ_FIRST(&state->outgoing))) {
                         type = p->type;
                         debug("dequeue packet: %u", type);
-                        buffer_free(&active_state->outgoing_packet);
-                        memcpy(&active_state->outgoing_packet, &p->payload,
-                            sizeof(Buffer));
-                        TAILQ_REMOVE(&active_state->outgoing, p, next);
+                        sshbuf_free(state->outgoing_packet);
+                        state->outgoing_packet = p->payload;
+                        TAILQ_REMOVE(&state->outgoing, p, next);
                         free(p);
-                        packet_send2_wrapped();
+                        if ((r = ssh_packet_send2_wrapped(ssh)) != 0)
+                                return r;
                 }
         }
-}
-
-void
-packet_send(void)
-{
-        if (compat20)
-                packet_send2();
-        else
-                packet_send1();
-        DBG(debug("packet_send done"));
+        return 0;
 }
 
 /*
@@ -1060,95 +1259,106 @@ packet_send(void)
  */
 
 int
-packet_read_seqnr(u_int32_t *seqnr_p)
+ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 {
-        int type, len, ret, cont, ms_remain = 0;
+        struct session_state *state = ssh->state;
+        int len, r, ms_remain, cont;
         fd_set *setp;
         char buf[8192];
         struct timeval timeout, start, *timeoutp = NULL;
 
         DBG(debug("packet_read()"));
 
-        setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
+        setp = (fd_set *)calloc(howmany(state->connection_in + 1,
             NFDBITS), sizeof(fd_mask));
+        if (setp == NULL)
+                return SSH_ERR_ALLOC_FAIL;
 
-        /* Since we are blocking, ensure that all written packets have been sent. */
-        packet_write_wait();
+        /*
+         * Since we are blocking, ensure that all written packets have
+         * been sent.
+         */
+        if ((r = ssh_packet_write_wait(ssh)) != 0)
+                return r;
 
         /* Stay in the loop until we have received a complete packet. */
         for (;;) {
                 /* Try to read a packet from the buffer. */
-                type = packet_read_poll_seqnr(seqnr_p);
+                r = ssh_packet_read_poll_seqnr(ssh, typep, seqnr_p);
+                if (r != 0)
+                        break;
                 if (!compat20 && (
-                    type == SSH_SMSG_SUCCESS
-                    || type == SSH_SMSG_FAILURE
-                    || type == SSH_CMSG_EOF
-                    || type == SSH_CMSG_EXIT_CONFIRMATION))
-                        packet_check_eom();
+                    *typep == SSH_SMSG_SUCCESS
+                    || *typep == SSH_SMSG_FAILURE
+                    || *typep == SSH_CMSG_EOF
+                    || *typep == SSH_CMSG_EXIT_CONFIRMATION))
+                        if ((r = sshpkt_get_end(ssh)) != 0)
+                                break;
                 /* If we got a packet, return it. */
-                if (type != SSH_MSG_NONE) {
-                        free(setp);
-                        return type;
-                }
+                if (*typep != SSH_MSG_NONE)
+                        break;
                 /*
                  * Otherwise, wait for some data to arrive, add it to the
                  * buffer, and try again.
                  */
-                memset(setp, 0, howmany(active_state->connection_in + 1,
+                memset(setp, 0, howmany(state->connection_in + 1,
                     NFDBITS) * sizeof(fd_mask));
-                FD_SET(active_state->connection_in, setp);
+                FD_SET(state->connection_in, setp);
 
-                if (active_state->packet_timeout_ms > 0) {
-                        ms_remain = active_state->packet_timeout_ms;
+                if (state->packet_timeout_ms > 0) {
+                        ms_remain = state->packet_timeout_ms;
                         timeoutp = &timeout;
                 }
                 /* Wait for some data to arrive. */
                 for (;;) {
-                        if (active_state->packet_timeout_ms != -1) {
+                        if (state->packet_timeout_ms != -1) {
                                 ms_to_timeval(&timeout, ms_remain);
                                 gettimeofday(&start, NULL);
                         }
-                        if ((ret = select(active_state->connection_in + 1, setp,
+                        if ((r = select(state->connection_in + 1, setp,
                             NULL, NULL, timeoutp)) >= 0)
                                 break;
                         if (errno != EAGAIN && errno != EINTR &&
                             errno != EWOULDBLOCK)
                                 break;
-                        if (active_state->packet_timeout_ms == -1)
+                        if (state->packet_timeout_ms == -1)
                                 continue;
                         ms_subtract_diff(&start, &ms_remain);
                         if (ms_remain <= 0) {
-                                ret = 0;
+                                r = 0;
                                 break;
                         }
                 }
-                if (ret == 0) {
-                        logit("Connection to %.200s timed out while "
-                            "waiting to read", get_remote_ipaddr());
-                        cleanup_exit(255);
-                }
+                if (r == 0)
+                        return SSH_ERR_CONN_TIMEOUT;
                 /* Read data from the socket. */
                 do {
                         cont = 0;
-                        len = roaming_read(active_state->connection_in, buf,
+                        len = roaming_read(state->connection_in, buf,
                             sizeof(buf), &cont);
                 } while (len == 0 && cont);
-                if (len == 0) {
-                        logit("Connection closed by %.200s", get_remote_ipaddr());
-                        cleanup_exit(255);
-                }
+                if (len == 0)
+                        return SSH_ERR_CONN_CLOSED;
                 if (len < 0)
-                        fatal("Read from socket failed: %.100s", strerror(errno));
+                        return SSH_ERR_SYSTEM_ERROR;
+
                 /* Append it to the buffer. */
-                packet_process_incoming(buf, len);
+                if ((r = ssh_packet_process_incoming(ssh, buf, len)) != 0)
+                        return r;
         }
-        /* NOTREACHED */
+        free(setp);
+        return r;
 }
 
 int
-packet_read(void)
+ssh_packet_read(struct ssh *ssh)
 {
-        return packet_read_seqnr(NULL);
+        u_char type;
+        int r;
+
+        if ((r = ssh_packet_read_seqnr(ssh, &type, NULL)) != 0)
+                fatal("%s: %s", __func__, ssh_err(r));
+        return type;
 }
 
 /*
@@ -1156,15 +1366,22 @@ packet_read(void)
  * that given, and gives a fatal error and exits if there is a mismatch.
  */
 
-void
-packet_read_expect(int expected_type)
+int
+ssh_packet_read_expect(struct ssh *ssh, u_int expected_type)
 {
-        int type;
+        int r;
+        u_char type;
 
-        type = packet_read();
-        if (type != expected_type)
-                packet_disconnect("Protocol error: expected packet type %d, got %d",
-                    expected_type, type);
+        if ((r = ssh_packet_read_seqnr(ssh, &type, NULL)) != 0)
+                return r;
+        if (type != expected_type) {
+                if ((r = sshpkt_disconnect(ssh,
+                    "Protocol error: expected packet type %d, got %d",
+                    expected_type, type)) != 0)
+                        return r;
+                return SSH_ERR_PROTOCOL_ERROR;
+        }
+        return 0;
 }
 
 /* Checks if a full packet is available in the data received so far via
@@ -1176,115 +1393,165 @@ packet_read_expect(int expected_type)
  * to higher levels.
  */
 
-static int
-packet_read_poll1(void)
+int
+ssh_packet_read_poll1(struct ssh *ssh, u_char *typep)
 {
+        struct session_state *state = ssh->state;
         u_int len, padded_len;
-        u_char *cp, type;
+        const char *emsg;
+        const u_char *cp;
+        u_char *p;
         u_int checksum, stored_checksum;
+        int r;
+
+        *typep = SSH_MSG_NONE;
 
         /* Check if input size is less than minimum packet size. */
-        if (buffer_len(&active_state->input) < 4 + 8)
-                return SSH_MSG_NONE;
+        if (sshbuf_len(state->input) < 4 + 8)
+                return 0;
         /* Get length of incoming packet. */
-        cp = buffer_ptr(&active_state->input);
-        len = get_u32(cp);
-        if (len < 1 + 2 + 2 || len > 256 * 1024)
-                packet_disconnect("Bad packet length %u.", len);
+        len = PEEK_U32(sshbuf_ptr(state->input));
+        if (len < 1 + 2 + 2 || len > 256 * 1024) {
+                if ((r = sshpkt_disconnect(ssh, "Bad packet length %u",
+                    len)) != 0)
+                        return r;
+                return SSH_ERR_CONN_CORRUPT;
+        }
         padded_len = (len + 8) & ~7;
 
         /* Check if the packet has been entirely received. */
-        if (buffer_len(&active_state->input) < 4 + padded_len)
-                return SSH_MSG_NONE;
+        if (sshbuf_len(state->input) < 4 + padded_len)
+                return 0;
 
         /* The entire packet is in buffer. */
 
         /* Consume packet length. */
-        buffer_consume(&active_state->input, 4);
+        if ((r = sshbuf_consume(state->input, 4)) != 0)
+                goto out;
 
         /*
          * Cryptographic attack detector for ssh
          * (C)1998 CORE-SDI, Buenos Aires Argentina
          * Ariel Futoransky(futo@core-sdi.com)
          */
-        if (!active_state->receive_context.plaintext) {
-                switch (detect_attack(buffer_ptr(&active_state->input),
-                    padded_len)) {
+        if (!state->receive_context.plaintext) {
+                emsg = NULL;
+                switch (detect_attack(&state->deattack,
+                    sshbuf_ptr(state->input), padded_len)) {
+                case DEATTACK_OK:
+                        break;
                 case DEATTACK_DETECTED:
-                        packet_disconnect("crc32 compensation attack: "
-                            "network attack detected");
+                        emsg = "crc32 compensation attack detected";
+                        break;
                 case DEATTACK_DOS_DETECTED:
-                        packet_disconnect("deattack denial of "
-                            "service detected");
+                        emsg = "deattack denial of service detected";
+                        break;
+                default:
+                        emsg = "deattack error";
+                        break;
+                }
+                if (emsg != NULL) {
+                        error("%s", emsg);
+                        if ((r = sshpkt_disconnect(ssh, "%s", emsg)) != 0 ||
+                            (r = ssh_packet_write_wait(ssh)) != 0)
+                                        return r;
+                        return SSH_ERR_CONN_CORRUPT;
                 }
         }
 
         /* Decrypt data to incoming_packet. */
-        buffer_clear(&active_state->incoming_packet);
-        cp = buffer_append_space(&active_state->incoming_packet, padded_len);
-        if (cipher_crypt(&active_state->receive_context, 0, cp,
-            buffer_ptr(&active_state->input), padded_len, 0, 0) != 0)
-                fatal("%s: cipher_crypt failed", __func__);
+        sshbuf_reset(state->incoming_packet);
+        if ((r = sshbuf_reserve(state->incoming_packet, padded_len, &p)) != 0)
+                goto out;
+        if ((r = cipher_crypt(&state->receive_context, 0, p,
+            sshbuf_ptr(state->input), padded_len, 0, 0)) != 0)
+                goto out;
 
-        buffer_consume(&active_state->input, padded_len);
+        if ((r = sshbuf_consume(state->input, padded_len)) != 0)
+                goto out;
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "read_poll plain: ");
-        buffer_dump(&active_state->incoming_packet);
+        sshbuf_dump(state->incoming_packet, stderr);
 #endif
 
         /* Compute packet checksum. */
-        checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
-            buffer_len(&active_state->incoming_packet) - 4);
+        checksum = ssh_crc32(sshbuf_ptr(state->incoming_packet),
+            sshbuf_len(state->incoming_packet) - 4);
 
         /* Skip padding. */
-        buffer_consume(&active_state->incoming_packet, 8 - len % 8);
+        if ((r = sshbuf_consume(state->incoming_packet, 8 - len % 8)) != 0)
+                goto out;
 
         /* Test check bytes. */
-        if (len != buffer_len(&active_state->incoming_packet))
-                packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
-                    len, buffer_len(&active_state->incoming_packet));
-
-        cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
-        stored_checksum = get_u32(cp);
-        if (checksum != stored_checksum)
-                packet_disconnect("Corrupted check bytes on input.");
-        buffer_consume_end(&active_state->incoming_packet, 4);
-
-        if (active_state->packet_compression) {
-                buffer_clear(&active_state->compression_buffer);
-                buffer_uncompress(&active_state->incoming_packet,
-                    &active_state->compression_buffer);
-                buffer_clear(&active_state->incoming_packet);
-                buffer_append(&active_state->incoming_packet,
-                    buffer_ptr(&active_state->compression_buffer),
-                    buffer_len(&active_state->compression_buffer));
-        }
-        active_state->p_read.packets++;
-        active_state->p_read.bytes += padded_len + 4;
-        type = buffer_get_char(&active_state->incoming_packet);
-        if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
-                packet_disconnect("Invalid ssh1 packet type: %d", type);
-        return type;
+        if (len != sshbuf_len(state->incoming_packet)) {
+                error("%s: len %d != sshbuf_len %zd", __func__,
+                    len, sshbuf_len(state->incoming_packet));
+                if ((r = sshpkt_disconnect(ssh, "invalid packet length")) != 0 ||
+                    (r = ssh_packet_write_wait(ssh)) != 0)
+                        return r;
+                return SSH_ERR_CONN_CORRUPT;
+        }
+
+        cp = sshbuf_ptr(state->incoming_packet) + len - 4;
+        stored_checksum = PEEK_U32(cp);
+        if (checksum != stored_checksum) {
+                error("Corrupted check bytes on input");
+                if ((r = sshpkt_disconnect(ssh, "connection corrupted")) != 0 ||
+                    (r = ssh_packet_write_wait(ssh)) != 0)
+                        return r;
+                return SSH_ERR_CONN_CORRUPT;
+        }
+        if ((r = sshbuf_consume_end(state->incoming_packet, 4)) < 0)
+                goto out;
+
+        if (state->packet_compression) {
+                sshbuf_reset(state->compression_buffer);
+                if ((r = uncompress_buffer(ssh, state->incoming_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
+                sshbuf_reset(state->incoming_packet);
+                if ((r = sshbuf_putb(state->incoming_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
+        }
+        state->p_read.packets++;
+        state->p_read.bytes += padded_len + 4;
+        if ((r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
+                goto out;
+        if (*typep < SSH_MSG_MIN || *typep > SSH_MSG_MAX) {
+                error("Invalid ssh1 packet type: %d", *typep);
+                if ((r = sshpkt_disconnect(ssh, "invalid packet type")) != 0 ||
+                    (r = ssh_packet_write_wait(ssh)) != 0)
+                        return r;
+                return SSH_ERR_PROTOCOL_ERROR;
+        }
+        r = 0;
+ out:
+        return r;
 }
 
-static int
-packet_read_poll2(u_int32_t *seqnr_p)
+int
+ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 {
+        struct session_state *state = ssh->state;
         u_int padlen, need;
-        u_char *macbuf = NULL, *cp, type;
-        u_int maclen, authlen = 0, aadlen = 0, block_size;
-        Enc *enc   = NULL;
-        Mac *mac   = NULL;
-        Comp *comp = NULL;
-
-        if (active_state->packet_discard)
-                return SSH_MSG_NONE;
-
-        if (active_state->newkeys[MODE_IN] != NULL) {
-                enc  = &active_state->newkeys[MODE_IN]->enc;
-                mac  = &active_state->newkeys[MODE_IN]->mac;
-                comp = &active_state->newkeys[MODE_IN]->comp;
+        u_char *cp, macbuf[SSH_DIGEST_MAX_LENGTH];
+        u_int maclen, aadlen = 0, authlen = 0, block_size;
+        struct sshenc *enc   = NULL;
+        struct sshmac *mac   = NULL;
+        struct sshcomp *comp = NULL;
+        int r;
+
+        *typep = SSH_MSG_NONE;
+
+        if (state->packet_discard)
+                return 0;
+
+        if (state->newkeys[MODE_IN] != NULL) {
+                enc  = &state->newkeys[MODE_IN]->enc;
+                mac  = &state->newkeys[MODE_IN]->mac;
+                comp = &state->newkeys[MODE_IN]->comp;
                 /* disable mac for authenticated encryption */
                 if ((authlen = cipher_authlen(enc->cipher)) != 0)
                         mac = NULL;
@@ -1293,69 +1560,71 @@ packet_read_poll2(u_int32_t *seqnr_p)
         block_size = enc ? enc->block_size : 8;
         aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
 
-        if (aadlen && active_state->packlen == 0) {
-                if (cipher_get_length(&active_state->receive_context,
-                    &active_state->packlen,
-                    active_state->p_read.seqnr,
-                    buffer_ptr(&active_state->input),
-                    buffer_len(&active_state->input)) != 0)
-                        return SSH_MSG_NONE;
-                if (active_state->packlen < 1 + 4 ||
-                    active_state->packlen > PACKET_MAX_SIZE) {
+        if (aadlen && state->packlen == 0) {
+                if (cipher_get_length(&state->receive_context,
+                    &state->packlen, state->p_read.seqnr,
+                    sshbuf_ptr(state->input), sshbuf_len(state->input)) != 0)
+                        return 0;
+                if (state->packlen < 1 + 4 ||
+                    state->packlen > PACKET_MAX_SIZE) {
 #ifdef PACKET_DEBUG
-                        buffer_dump(&active_state->input);
+                        sshbuf_dump(state->input, stderr);
 #endif
-                        logit("Bad packet length %u.", active_state->packlen);
-                        packet_disconnect("Packet corrupt");
+                        logit("Bad packet length %u.", state->packlen);
+                        if ((r = sshpkt_disconnect(ssh, "Packet corrupt")) != 0)
+                                return r;
                 }
-                buffer_clear(&active_state->incoming_packet);
-        } else if (active_state->packlen == 0) {
+                sshbuf_reset(state->incoming_packet);
+        } else if (state->packlen == 0) {
                 /*
                  * check if input size is less than the cipher block size,
                  * decrypt first block and extract length of incoming packet
                  */
-                if (buffer_len(&active_state->input) < block_size)
-                        return SSH_MSG_NONE;
-                buffer_clear(&active_state->incoming_packet);
-                cp = buffer_append_space(&active_state->incoming_packet,
-                    block_size);
-                if (cipher_crypt(&active_state->receive_context,
-                    active_state->p_read.seqnr, cp,
-                    buffer_ptr(&active_state->input), block_size, 0, 0) != 0)
-                        fatal("Decryption integrity check failed");
-                cp = buffer_ptr(&active_state->incoming_packet);
-                active_state->packlen = get_u32(cp);
-                if (active_state->packlen < 1 + 4 ||
-                    active_state->packlen > PACKET_MAX_SIZE) {
+                if (sshbuf_len(state->input) < block_size)
+                        return 0;
+                sshbuf_reset(state->incoming_packet);
+                if ((r = sshbuf_reserve(state->incoming_packet, block_size,
+                    &cp)) != 0)
+                        goto out;
+                if ((r = cipher_crypt(&state->receive_context,
+                    state->p_send.seqnr, cp, sshbuf_ptr(state->input),
+                    block_size, 0, 0)) != 0)
+                        goto out;
+                state->packlen = PEEK_U32(sshbuf_ptr(state->incoming_packet));
+                if (state->packlen < 1 + 4 ||
+                    state->packlen > PACKET_MAX_SIZE) {
 #ifdef PACKET_DEBUG
-                        buffer_dump(&active_state->incoming_packet);
+                        fprintf(stderr, "input: \n");
+                        sshbuf_dump(state->input, stderr);
+                        fprintf(stderr, "incoming_packet: \n");
+                        sshbuf_dump(state->incoming_packet, stderr);
 #endif
-                        logit("Bad packet length %u.", active_state->packlen);
-                        packet_start_discard(enc, mac, active_state->packlen,
-                            PACKET_MAX_SIZE);
-                        return SSH_MSG_NONE;
+                        logit("Bad packet length %u.", state->packlen);
+                        return ssh_packet_start_discard(ssh, enc, mac,
+                            state->packlen, PACKET_MAX_SIZE);
                 }
-                buffer_consume(&active_state->input, block_size);
+                if ((r = sshbuf_consume(state->input, block_size)) != 0)
+                        goto out;
         }
-        DBG(debug("input: packet len %u", active_state->packlen+4));
+        DBG(debug("input: packet len %u", state->packlen+4));
+
         if (aadlen) {
                 /* only the payload is encrypted */
-                need = active_state->packlen;
+                need = state->packlen;
         } else {
                 /*
                  * the payload size and the payload are encrypted, but we
                  * have a partial packet of block_size bytes
                  */
-                need = 4 + active_state->packlen - block_size;
+                need = 4 + state->packlen - block_size;
         }
         DBG(debug("partial packet: block %d, need %d, maclen %d, authlen %d,"
             " aadlen %d", block_size, need, maclen, authlen, aadlen));
         if (need % block_size != 0) {
                 logit("padding error: need %d block %d mod %d",
                     need, block_size, need % block_size);
-                packet_start_discard(enc, mac, active_state->packlen,
-                    PACKET_MAX_SIZE - block_size);
-                return SSH_MSG_NONE;
+                return ssh_packet_start_discard(ssh, enc, mac,
+                    state->packlen, PACKET_MAX_SIZE - block_size);
         }
         /*
          * check if the entire packet has been received and
@@ -1365,167 +1634,197 @@ packet_read_poll2(u_int32_t *seqnr_p)
          * 'authlen' bytes of authentication tag or
          * 'maclen' bytes of message authentication code.
          */
-        if (buffer_len(&active_state->input) < aadlen + need + authlen + maclen)
-                return SSH_MSG_NONE;
+        if (sshbuf_len(state->input) < aadlen + need + authlen + maclen)
+                return 0;
 #ifdef PACKET_DEBUG
         fprintf(stderr, "read_poll enc/full: ");
-        buffer_dump(&active_state->input);
+        sshbuf_dump(state->input, stderr);
 #endif
         /* EtM: compute mac over encrypted input */
-        if (mac && mac->enabled && mac->etm)
-                macbuf = mac_compute(mac, active_state->p_read.seqnr,
-                    buffer_ptr(&active_state->input), aadlen + need);
-        cp = buffer_append_space(&active_state->incoming_packet, aadlen + need);
-        if (cipher_crypt(&active_state->receive_context,
-            active_state->p_read.seqnr, cp,
-            buffer_ptr(&active_state->input), need, aadlen, authlen) != 0)
-                fatal("Decryption integrity check failed");
-        buffer_consume(&active_state->input, aadlen + need + authlen);
+        if (mac && mac->enabled && mac->etm) {
+                if ((r = mac_compute(mac, state->p_read.seqnr,
+                    sshbuf_ptr(state->input), aadlen + need,
+                    macbuf, sizeof(macbuf))) != 0)
+                        goto out;
+        }
+        if ((r = sshbuf_reserve(state->incoming_packet, aadlen + need,
+            &cp)) != 0)
+                goto out;
+        if ((r = cipher_crypt(&state->receive_context, state->p_read.seqnr, cp,
+            sshbuf_ptr(state->input), need, aadlen, authlen)) != 0)
+                goto out;
+        if ((r = sshbuf_consume(state->input, aadlen + need + authlen)) != 0)
+                goto out;
         /*
          * compute MAC over seqnr and packet,
          * increment sequence number for incoming packet
          */
         if (mac && mac->enabled) {
                 if (!mac->etm)
-                        macbuf = mac_compute(mac, active_state->p_read.seqnr,
-                            buffer_ptr(&active_state->incoming_packet),
-                            buffer_len(&active_state->incoming_packet));
-                if (timingsafe_bcmp(macbuf, buffer_ptr(&active_state->input),
+                        if ((r = mac_compute(mac, state->p_read.seqnr,
+                            sshbuf_ptr(state->incoming_packet),
+                            sshbuf_len(state->incoming_packet),
+                            macbuf, sizeof(macbuf))) != 0)
+                                goto out;
+                if (timingsafe_bcmp(macbuf, sshbuf_ptr(state->input),
                     mac->mac_len) != 0) {
                         logit("Corrupted MAC on input.");
                         if (need > PACKET_MAX_SIZE)
-                                fatal("internal error need %d", need);
-                        packet_start_discard(enc, mac, active_state->packlen,
-                            PACKET_MAX_SIZE - need);
-                        return SSH_MSG_NONE;
+                                return SSH_ERR_INTERNAL_ERROR;
+                        return ssh_packet_start_discard(ssh, enc, mac,
+                            state->packlen, PACKET_MAX_SIZE - need);
                 }
-                                
-                DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
-                buffer_consume(&active_state->input, mac->mac_len);
+
+                DBG(debug("MAC #%d ok", state->p_read.seqnr));
+                if ((r = sshbuf_consume(state->input, mac->mac_len)) != 0)
+                        goto out;
         }
-        /* XXX now it's safe to use fatal/packet_disconnect */
         if (seqnr_p != NULL)
-                *seqnr_p = active_state->p_read.seqnr;
-        if (++active_state->p_read.seqnr == 0)
+                *seqnr_p = state->p_read.seqnr;
+        if (++state->p_read.seqnr == 0)
                 logit("incoming seqnr wraps around");
-        if (++active_state->p_read.packets == 0)
-                if (!(datafellows & SSH_BUG_NOREKEY))
-                        fatal("XXX too many packets with same key");
-        active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
-        active_state->p_read.bytes += active_state->packlen + 4;
+        if (++state->p_read.packets == 0)
+                if (!(ssh->compat & SSH_BUG_NOREKEY))
+                        return SSH_ERR_NEED_REKEY;
+        state->p_read.blocks += (state->packlen + 4) / block_size;
+        state->p_read.bytes += state->packlen + 4;
 
         /* get padlen */
-        cp = buffer_ptr(&active_state->incoming_packet);
-        padlen = cp[4];
+        padlen = sshbuf_ptr(state->incoming_packet)[4];
         DBG(debug("input: padlen %d", padlen));
-        if (padlen < 4)
-                packet_disconnect("Corrupted padlen %d on input.", padlen);
+        if (padlen < 4) {
+                if ((r = sshpkt_disconnect(ssh,
+                    "Corrupted padlen %d on input.", padlen)) != 0 ||
+                    (r = ssh_packet_write_wait(ssh)) != 0)
+                        return r;
+                return SSH_ERR_CONN_CORRUPT;
+        }
 
         /* skip packet size + padlen, discard padding */
-        buffer_consume(&active_state->incoming_packet, 4 + 1);
-        buffer_consume_end(&active_state->incoming_packet, padlen);
+        if ((r = sshbuf_consume(state->incoming_packet, 4 + 1)) != 0 ||
+            ((r = sshbuf_consume_end(state->incoming_packet, padlen)) != 0))
+                goto out;
 
-        DBG(debug("input: len before de-compress %d",
-            buffer_len(&active_state->incoming_packet)));
+        DBG(debug("input: len before de-compress %zd",
+            sshbuf_len(state->incoming_packet)));
         if (comp && comp->enabled) {
-                buffer_clear(&active_state->compression_buffer);
-                buffer_uncompress(&active_state->incoming_packet,
-                    &active_state->compression_buffer);
-                buffer_clear(&active_state->incoming_packet);
-                buffer_append(&active_state->incoming_packet,
-                    buffer_ptr(&active_state->compression_buffer),
-                    buffer_len(&active_state->compression_buffer));
-                DBG(debug("input: len after de-compress %d",
-                    buffer_len(&active_state->incoming_packet)));
+                sshbuf_reset(state->compression_buffer);
+                if ((r = uncompress_buffer(ssh, state->incoming_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
+                sshbuf_reset(state->incoming_packet);
+                if ((r = sshbuf_putb(state->incoming_packet,
+                    state->compression_buffer)) != 0)
+                        goto out;
+                DBG(debug("input: len after de-compress %zd",
+                    sshbuf_len(state->incoming_packet)));
         }
         /*
          * get packet type, implies consume.
          * return length of payload (without type field)
          */
-        type = buffer_get_char(&active_state->incoming_packet);
-        if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
-                packet_disconnect("Invalid ssh2 packet type: %d", type);
-        if (type == SSH2_MSG_NEWKEYS)
-                set_newkeys(MODE_IN);
-        else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
-            !active_state->server_side)
-                packet_enable_delayed_compress();
+        if ((r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
+                goto out;
+        if (*typep < SSH2_MSG_MIN || *typep >= SSH2_MSG_LOCAL_MIN) {
+                if ((r = sshpkt_disconnect(ssh,
+                    "Invalid ssh2 packet type: %d", *typep)) != 0 ||
+                    (r = ssh_packet_write_wait(ssh)) != 0)
+                        return r;
+                return SSH_ERR_PROTOCOL_ERROR;
+        }
+        if (*typep == SSH2_MSG_NEWKEYS)
+                r = ssh_set_newkeys(ssh, MODE_IN);
+        else if (*typep == SSH2_MSG_USERAUTH_SUCCESS && !state->server_side)
+                r = ssh_packet_enable_delayed_compress(ssh);
+        else
+                r = 0;
 #ifdef PACKET_DEBUG
-        fprintf(stderr, "read/plain[%d]:\r\n", type);
-        buffer_dump(&active_state->incoming_packet);
+        fprintf(stderr, "read/plain[%d]:\r\n", *typep);
+        sshbuf_dump(state->incoming_packet, stderr);
 #endif
         /* reset for next packet */
-        active_state->packlen = 0;
-        return type;
+        state->packlen = 0;
+ out:
+        return r;
 }
 
 int
-packet_read_poll_seqnr(u_int32_t *seqnr_p)
+ssh_packet_read_poll_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
 {
+        struct session_state *state = ssh->state;
         u_int reason, seqnr;
-        u_char type;
-        char *msg;
+        int r;
+        u_char *msg;
 
         for (;;) {
+                msg = NULL;
                 if (compat20) {
-                        type = packet_read_poll2(seqnr_p);
-                        if (type) {
-                                active_state->keep_alive_timeouts = 0;
-                                DBG(debug("received packet type %d", type));
+                        r = ssh_packet_read_poll2(ssh, typep, seqnr_p);
+                        if (r != 0)
+                                return r;
+                        if (*typep) {
+                                state->keep_alive_timeouts = 0;
+                                DBG(debug("received packet type %d", *typep));
                         }
-                        switch (type) {
+                        switch (*typep) {
                         case SSH2_MSG_IGNORE:
                                 debug3("Received SSH2_MSG_IGNORE");
                                 break;
                         case SSH2_MSG_DEBUG:
-                                packet_get_char();
-                                msg = packet_get_string(NULL);
+                                if ((r = sshpkt_get_u8(ssh, NULL)) != 0 ||
+                                    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
+                                    (r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
+                                        if (msg)
+                                                free(msg);
+                                        return r;
+                                }
                                 debug("Remote: %.900s", msg);
                                 free(msg);
-                                msg = packet_get_string(NULL);
-                                free(msg);
                                 break;
                         case SSH2_MSG_DISCONNECT:
-                                reason = packet_get_int();
-                                msg = packet_get_string(NULL);
+                                if ((r = sshpkt_get_u32(ssh, &reason)) != 0 ||
+                                    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
+                                        return r;
                                 /* Ignore normal client exit notifications */
-                                do_log2(active_state->server_side &&
+                                do_log2(ssh->state->server_side &&
                                     reason == SSH2_DISCONNECT_BY_APPLICATION ?
                                     SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR,
                                     "Received disconnect from %s: %u: %.400s",
-                                    get_remote_ipaddr(), reason, msg);
+                                    ssh_remote_ipaddr(ssh), reason, msg);
                                 free(msg);
-                                cleanup_exit(255);
-                                break;
+                                return SSH_ERR_DISCONNECTED;
                         case SSH2_MSG_UNIMPLEMENTED:
-                                seqnr = packet_get_int();
+                                if ((r = sshpkt_get_u32(ssh, &seqnr)) != 0)
+                                        return r;
                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
                                     seqnr);
                                 break;
                         default:
-                                return type;
+                                return 0;
                         }
                 } else {
-                        type = packet_read_poll1();
-                        switch (type) {
+                        r = ssh_packet_read_poll1(ssh, typep);
+                        switch (*typep) {
                         case SSH_MSG_NONE:
                                 return SSH_MSG_NONE;
                         case SSH_MSG_IGNORE:
                                 break;
                         case SSH_MSG_DEBUG:
-                                msg = packet_get_string(NULL);
+                                if ((r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
+                                        return r;
                                 debug("Remote: %.900s", msg);
                                 free(msg);
                                 break;
                         case SSH_MSG_DISCONNECT:
-                                msg = packet_get_string(NULL);
+                                if ((r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
+                                        return r;
                                 error("Received disconnect from %s: %.400s",
-                                    get_remote_ipaddr(), msg);
-                                cleanup_exit(255);
-                                break;
+                                    ssh_remote_ipaddr(ssh), msg);
+                                free(msg);
+                                return SSH_ERR_DISCONNECTED;
                         default:
-                                DBG(debug("received packet type %d", type));
-                                return type;
+                                DBG(debug("received packet type %d", *typep));
+                                return 0;
                         }
                 }
         }
@@ -1536,113 +1835,31 @@ packet_read_poll_seqnr(u_int32_t *seqnr_p)
  * together with packet_read_poll.
  */
 
-void
-packet_process_incoming(const char *buf, u_int len)
-{
-        if (active_state->packet_discard) {
-                active_state->keep_alive_timeouts = 0; /* ?? */
-                if (len >= active_state->packet_discard)
-                        packet_stop_discard();
-                active_state->packet_discard -= len;
-                return;
-        }
-        buffer_append(&active_state->input, buf, len);
-}
-
-/* Returns a character from the packet. */
-
-u_int
-packet_get_char(void)
-{
-        char ch;
-
-        buffer_get(&active_state->incoming_packet, &ch, 1);
-        return (u_char) ch;
-}
-
-/* Returns an integer from the packet data. */
-
-u_int
-packet_get_int(void)
-{
-        return buffer_get_int(&active_state->incoming_packet);
-}
-
-/* Returns an 64 bit integer from the packet data. */
-
-u_int64_t
-packet_get_int64(void)
-{
-        return buffer_get_int64(&active_state->incoming_packet);
-}
-
-/*
- * Returns an arbitrary precision integer from the packet data.  The integer
- * must have been initialized before this call.
- */
-
-#ifdef WITH_OPENSSL
-void
-packet_get_bignum(BIGNUM * value)
-{
-        buffer_get_bignum(&active_state->incoming_packet, value);
-}
-
-void
-packet_get_bignum2(BIGNUM * value)
-{
-        buffer_get_bignum2(&active_state->incoming_packet, value);
-}
-
-#ifdef OPENSSL_HAS_ECC
-void
-packet_get_ecpoint(const EC_GROUP *curve, EC_POINT *point)
-{
-        buffer_get_ecpoint(&active_state->incoming_packet, curve, point);
-}
-#endif
-
-void *
-packet_get_raw(u_int *length_ptr)
-{
-        u_int bytes = buffer_len(&active_state->incoming_packet);
-
-        if (length_ptr != NULL)
-                *length_ptr = bytes;
-        return buffer_ptr(&active_state->incoming_packet);
-}
-#endif
-
 int
-packet_remaining(void)
+ssh_packet_process_incoming(struct ssh *ssh, const char *buf, u_int len)
 {
-        return buffer_len(&active_state->incoming_packet);
-}
-
-/*
- * Returns a string from the packet data.  The string is allocated using
- * xmalloc; it is the responsibility of the calling program to free it when
- * no longer needed.  The length_ptr argument may be NULL, or point to an
- * integer into which the length of the string is stored.
- */
+        struct session_state *state = ssh->state;
+        int r;
 
-void *
-packet_get_string(u_int *length_ptr)
-{
-        return buffer_get_string(&active_state->incoming_packet, length_ptr);
-}
+        if (state->packet_discard) {
+                state->keep_alive_timeouts = 0; /* ?? */
+                if (len >= state->packet_discard) {
+                        if ((r = ssh_packet_stop_discard(ssh)) != 0)
+                                return r;
+                }
+                state->packet_discard -= len;
+                return 0;
+        }
+        if ((r = sshbuf_put(ssh->state->input, buf, len)) != 0)
+                return r;
 
-const void *
-packet_get_string_ptr(u_int *length_ptr)
-{
-        return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
+        return 0;
 }
 
-/* Ensures the returned string has no embedded \0 characters in it. */
-char *
-packet_get_cstring(u_int *length_ptr)
+int
+ssh_packet_remaining(struct ssh *ssh)
 {
-        return buffer_get_cstring(&active_state->incoming_packet, length_ptr);
+        return sshbuf_len(ssh->state->incoming_packet);
 }
 
 /*
@@ -1651,16 +1868,16 @@ packet_get_cstring(u_int *length_ptr)
  * message is printed immediately, but only if the client is being executed
  * in verbose mode.  These messages are primarily intended to ease debugging
  * authentication problems.   The length of the formatted message must not
- * exceed 1024 bytes.  This will automatically call packet_write_wait.
+ * exceed 1024 bytes.  This will automatically call ssh_packet_write_wait.
  */
-
 void
-packet_send_debug(const char *fmt,...)
+ssh_packet_send_debug(struct ssh *ssh, const char *fmt,...)
 {
         char buf[1024];
         va_list args;
+        int r;
 
-        if (compat20 && (datafellows & SSH_BUG_DEBUG))
+        if (compat20 && (ssh->compat & SSH_BUG_DEBUG))
                 return;
 
         va_start(args, fmt);
@@ -1668,16 +1885,41 @@ packet_send_debug(const char *fmt,...)
         va_end(args);
 
         if (compat20) {
-                packet_start(SSH2_MSG_DEBUG);
-                packet_put_char(0);     /* bool: always display */
-                packet_put_cstring(buf);
-                packet_put_cstring("");
+                if ((r = sshpkt_start(ssh, SSH2_MSG_DEBUG)) != 0 ||
+                    (r = sshpkt_put_u8(ssh, 0)) != 0 || /* always display */
+                    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0)
+                        fatal("%s: %s", __func__, ssh_err(r));
         } else {
-                packet_start(SSH_MSG_DEBUG);
-                packet_put_cstring(buf);
+                if ((r = sshpkt_start(ssh, SSH_MSG_DEBUG)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0)
+                        fatal("%s: %s", __func__, ssh_err(r));
+        }
+        if ((r = ssh_packet_write_wait(ssh)) != 0)
+                fatal("%s: %s", __func__, ssh_err(r));
+}
+
+/*
+ * Pretty-print connection-terminating errors and exit.
+ */
+void
+sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
+{
+        switch (r) {
+        case SSH_ERR_CONN_CLOSED:
+                logit("Connection closed by %.200s", ssh_remote_ipaddr(ssh));
+                cleanup_exit(255);
+        case SSH_ERR_CONN_TIMEOUT:
+                logit("Connection to %.200s timed out while "
+                    "waiting to write", ssh_remote_ipaddr(ssh));
+                cleanup_exit(255);
+        default:
+                fatal("%s%sConnection to %.200s: %s",
+                    tag != NULL ? tag : "", tag != NULL ? ": " : "",
+                    ssh_remote_ipaddr(ssh), ssh_err(r));
         }
-        packet_send();
-        packet_write_wait();
 }
 
 /*
@@ -1686,13 +1928,13 @@ packet_send_debug(const char *fmt,...)
  * should not contain a newline.  The length of the formatted message must
  * not exceed 1024 bytes.
  */
-
 void
-packet_disconnect(const char *fmt,...)
+ssh_packet_disconnect(struct ssh *ssh, const char *fmt,...)
 {
         char buf[1024];
         va_list args;
         static int disconnecting = 0;
+        int r;
 
         if (disconnecting)      /* Guard against recursive invocations. */
                 fatal("packet_disconnect called recursively.");
@@ -1709,87 +1951,88 @@ packet_disconnect(const char *fmt,...)
         /* Display the error locally */
         logit("Disconnecting: %.100s", buf);
 
-        /* Send the disconnect message to the other side, and wait for it to get sent. */
-        if (compat20) {
-                packet_start(SSH2_MSG_DISCONNECT);
-                packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
-                packet_put_cstring(buf);
-                packet_put_cstring("");
-        } else {
-                packet_start(SSH_MSG_DISCONNECT);
-                packet_put_cstring(buf);
-        }
-        packet_send();
-        packet_write_wait();
+        /*
+         * Send the disconnect message to the other side, and wait
+         * for it to get sent.
+         */
+        if ((r = sshpkt_disconnect(ssh, "%s", buf)) != 0)
+                sshpkt_fatal(ssh, __func__, r);
 
-        /* Stop listening for connections. */
-        channel_close_all();
+        if ((r = ssh_packet_write_wait(ssh)) != 0)
+                sshpkt_fatal(ssh, __func__, r);
 
         /* Close the connection. */
-        packet_close();
+        ssh_packet_close(ssh);
         cleanup_exit(255);
 }
 
-/* Checks if there is any buffered output, and tries to write some of the output. */
-
-void
-packet_write_poll(void)
+/*
+ * Checks if there is any buffered output, and tries to write some of
+ * the output.
+ */
+int
+ssh_packet_write_poll(struct ssh *ssh)
 {
-        int len = buffer_len(&active_state->output);
-        int cont;
+        struct session_state *state = ssh->state;
+        int len = sshbuf_len(state->output);
+        int cont, r;
 
         if (len > 0) {
                 cont = 0;
-                len = roaming_write(active_state->connection_out,
-                    buffer_ptr(&active_state->output), len, &cont);
+                len = roaming_write(state->connection_out,
+                    sshbuf_ptr(state->output), len, &cont);
                 if (len == -1) {
                         if (errno == EINTR || errno == EAGAIN ||
                             errno == EWOULDBLOCK)
-                                return;
-                        fatal("Write failed: %.100s", strerror(errno));
+                                return 0;
+                        return SSH_ERR_SYSTEM_ERROR;
                 }
                 if (len == 0 && !cont)
-                        fatal("Write connection closed");
-                buffer_consume(&active_state->output, len);
+                        return SSH_ERR_CONN_CLOSED;
+                if ((r = sshbuf_consume(state->output, len)) != 0)
+                        return r;
         }
+        return 0;
 }
 
 /*
  * Calls packet_write_poll repeatedly until all pending output data has been
  * written.
  */
-
-void
-packet_write_wait(void)
+int
+ssh_packet_write_wait(struct ssh *ssh)
 {
         fd_set *setp;
-        int ret, ms_remain = 0;
+        int ret, r, ms_remain = 0;
         struct timeval start, timeout, *timeoutp = NULL;
+        struct session_state *state = ssh->state;
 
-        setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
+        setp = (fd_set *)calloc(howmany(state->connection_out + 1,
             NFDBITS), sizeof(fd_mask));
-        packet_write_poll();
-        while (packet_have_data_to_write()) {
-                memset(setp, 0, howmany(active_state->connection_out + 1,
+        if (setp == NULL)
+                return SSH_ERR_ALLOC_FAIL;
+        ssh_packet_write_poll(ssh);
+        while (ssh_packet_have_data_to_write(ssh)) {
+                memset(setp, 0, howmany(state->connection_out + 1,
                     NFDBITS) * sizeof(fd_mask));
-                FD_SET(active_state->connection_out, setp);
+                FD_SET(state->connection_out, setp);
 
-                if (active_state->packet_timeout_ms > 0) {
-                        ms_remain = active_state->packet_timeout_ms;
+                if (state->packet_timeout_ms > 0) {
+                        ms_remain = state->packet_timeout_ms;
                         timeoutp = &timeout;
                 }
                 for (;;) {
-                        if (active_state->packet_timeout_ms != -1) {
+                        if (state->packet_timeout_ms != -1) {
                                 ms_to_timeval(&timeout, ms_remain);
                                 gettimeofday(&start, NULL);
                         }
-                        if ((ret = select(active_state->connection_out + 1,
+                        if ((ret = select(state->connection_out + 1,
                             NULL, setp, NULL, timeoutp)) >= 0)
                                 break;
                         if (errno != EAGAIN && errno != EINTR &&
                             errno != EWOULDBLOCK)
                                 break;
-                        if (active_state->packet_timeout_ms == -1)
+                        if (state->packet_timeout_ms == -1)
                                 continue;
                         ms_subtract_diff(&start, &ms_remain);
                         if (ms_remain <= 0) {
@@ -1798,45 +2041,48 @@ packet_write_wait(void)
                         }
                 }
                 if (ret == 0) {
-                        logit("Connection to %.200s timed out while "
-                            "waiting to write", get_remote_ipaddr());
-                        cleanup_exit(255);
+                        free(setp);
+                        return SSH_ERR_CONN_TIMEOUT;
+                }
+                if ((r = ssh_packet_write_poll(ssh)) != 0) {
+                        free(setp);
+                        return r;
                 }
-                packet_write_poll();
         }
         free(setp);
+        return 0;
 }
 
 /* Returns true if there is buffered data to write to the connection. */
 
 int
-packet_have_data_to_write(void)
+ssh_packet_have_data_to_write(struct ssh *ssh)
 {
-        return buffer_len(&active_state->output) != 0;
+        return sshbuf_len(ssh->state->output) != 0;
 }
 
 /* Returns true if there is not too much data to write to the connection. */
 
 int
-packet_not_very_much_data_to_write(void)
+ssh_packet_not_very_much_data_to_write(struct ssh *ssh)
 {
-        if (active_state->interactive_mode)
-                return buffer_len(&active_state->output) < 16384;
+        if (ssh->state->interactive_mode)
+                return sshbuf_len(ssh->state->output) < 16384;
         else
-                return buffer_len(&active_state->output) < 128 * 1024;
+                return sshbuf_len(ssh->state->output) < 128 * 1024;
 }
 
-static void
-packet_set_tos(int tos)
+void
+ssh_packet_set_tos(struct ssh *ssh, int tos)
 {
 #ifndef IP_TOS_IS_BROKEN
-        if (!packet_connection_is_on_socket())
+        if (!ssh_packet_connection_is_on_socket(ssh))
                 return;
-        switch (packet_connection_af()) {
+        switch (ssh_packet_connection_af(ssh)) {
 # ifdef IP_TOS
         case AF_INET:
                 debug3("%s: set IP_TOS 0x%02x", __func__, tos);
-                if (setsockopt(active_state->connection_in,
+                if (setsockopt(ssh->state->connection_in,
                     IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0)
                         error("setsockopt IP_TOS %d: %.100s:",
                             tos, strerror(errno));
@@ -1845,7 +2091,7 @@ packet_set_tos(int tos)
 # ifdef IPV6_TCLASS
         case AF_INET6:
                 debug3("%s: set IPV6_TCLASS 0x%02x", __func__, tos);
-                if (setsockopt(active_state->connection_in,
+                if (setsockopt(ssh->state->connection_in,
                     IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) < 0)
                         error("setsockopt IPV6_TCLASS %d: %.100s:",
                             tos, strerror(errno));
@@ -1858,71 +2104,69 @@ packet_set_tos(int tos)
 /* Informs that the current session is interactive.  Sets IP flags for that. */
 
 void
-packet_set_interactive(int interactive, int qos_interactive, int qos_bulk)
+ssh_packet_set_interactive(struct ssh *ssh, int interactive, int qos_interactive, int qos_bulk)
 {
-        if (active_state->set_interactive_called)
+        struct session_state *state = ssh->state;
+
+        if (state->set_interactive_called)
                 return;
-        active_state->set_interactive_called = 1;
+        state->set_interactive_called = 1;
 
         /* Record that we are in interactive mode. */
-        active_state->interactive_mode = interactive;
+        state->interactive_mode = interactive;
 
         /* Only set socket options if using a socket.  */
-        if (!packet_connection_is_on_socket())
+        if (!ssh_packet_connection_is_on_socket(ssh))
                 return;
-        set_nodelay(active_state->connection_in);
-        packet_set_tos(interactive ? qos_interactive : qos_bulk);
+        set_nodelay(state->connection_in);
+        ssh_packet_set_tos(ssh, interactive ? qos_interactive :
+            qos_bulk);
 }
 
 /* Returns true if the current connection is interactive. */
 
 int
-packet_is_interactive(void)
+ssh_packet_is_interactive(struct ssh *ssh)
 {
-        return active_state->interactive_mode;
+        return ssh->state->interactive_mode;
 }
 
 int
-packet_set_maxsize(u_int s)
+ssh_packet_set_maxsize(struct ssh *ssh, u_int s)
 {
-        if (active_state->set_maxsize_called) {
+        struct session_state *state = ssh->state;
+
+        if (state->set_maxsize_called) {
                 logit("packet_set_maxsize: called twice: old %d new %d",
-                    active_state->max_packet_size, s);
+                    state->max_packet_size, s);
                 return -1;
         }
         if (s < 4 * 1024 || s > 1024 * 1024) {
                 logit("packet_set_maxsize: bad size %d", s);
                 return -1;
         }
-        active_state->set_maxsize_called = 1;
+        state->set_maxsize_called = 1;
         debug("packet_set_maxsize: setting to %d", s);
-        active_state->max_packet_size = s;
+        state->max_packet_size = s;
         return s;
 }
 
 int
-packet_inc_alive_timeouts(void)
+ssh_packet_inc_alive_timeouts(struct ssh *ssh)
 {
-        return ++active_state->keep_alive_timeouts;
+        return ++ssh->state->keep_alive_timeouts;
 }
 
 void
-packet_set_alive_timeouts(int ka)
+ssh_packet_set_alive_timeouts(struct ssh *ssh, int ka)
 {
-        active_state->keep_alive_timeouts = ka;
+        ssh->state->keep_alive_timeouts = ka;
 }
 
 u_int
-packet_get_maxsize(void)
+ssh_packet_get_maxsize(struct ssh *ssh)
 {
-        return active_state->max_packet_size;
-}
-
-/* roundup current message to pad bytes */
-void
-packet_add_padding(u_char pad)
-{
-        active_state->extra_pad = pad;
+        return ssh->state->max_packet_size;
 }
 
 /*
@@ -1937,155 +2181,718 @@ packet_add_padding(u_char pad)
  * protection measure against advanced traffic analysis techniques.
  */
 void
-packet_send_ignore(int nbytes)
+ssh_packet_send_ignore(struct ssh *ssh, int nbytes)
 {
         u_int32_t rnd = 0;
-        int i;
+        int r, i;
 
-        packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
-        packet_put_int(nbytes);
+        if ((r = sshpkt_start(ssh, compat20 ?
+            SSH2_MSG_IGNORE : SSH_MSG_IGNORE)) != 0 ||
+            (r = sshpkt_put_u32(ssh, nbytes)) != 0)
+                fatal("%s: %s", __func__, ssh_err(r));
         for (i = 0; i < nbytes; i++) {
                 if (i % 4 == 0)
                         rnd = arc4random();
-                packet_put_char((u_char)rnd & 0xff);
+                if ((r = sshpkt_put_u8(ssh, (u_char)rnd & 0xff)) != 0)
+                        fatal("%s: %s", __func__, ssh_err(r));
                 rnd >>= 8;
         }
 }
 
 #define MAX_PACKETS     (1U<<31)
 int
-packet_need_rekeying(void)
+ssh_packet_need_rekeying(struct ssh *ssh)
 {
-        if (datafellows & SSH_BUG_NOREKEY)
+        struct session_state *state = ssh->state;
+
+        if (ssh->compat & SSH_BUG_NOREKEY)
                 return 0;
         return
-            (active_state->p_send.packets > MAX_PACKETS) ||
-            (active_state->p_read.packets > MAX_PACKETS) ||
-            (active_state->max_blocks_out &&
-                (active_state->p_send.blocks > active_state->max_blocks_out)) ||
-            (active_state->max_blocks_in &&
-                (active_state->p_read.blocks > active_state->max_blocks_in)) ||
-            (active_state->rekey_interval != 0 && active_state->rekey_time +
-                 active_state->rekey_interval <= monotime());
+            (state->p_send.packets > MAX_PACKETS) ||
+            (state->p_read.packets > MAX_PACKETS) ||
+            (state->max_blocks_out &&
+                (state->p_send.blocks > state->max_blocks_out)) ||
+            (state->max_blocks_in &&
+                (state->p_read.blocks > state->max_blocks_in)) ||
+            (state->rekey_interval != 0 && state->rekey_time +
+                 state->rekey_interval <= monotime());
 }
 
 void
-packet_set_rekey_limits(u_int32_t bytes, time_t seconds)
+ssh_packet_set_rekey_limits(struct ssh *ssh, u_int32_t bytes, time_t seconds)
 {
         debug3("rekey after %lld bytes, %d seconds", (long long)bytes,
             (int)seconds);
-        active_state->rekey_limit = bytes;
-        active_state->rekey_interval = seconds;
-        /*
-         * We set the time here so that in post-auth privsep slave we count
-         * from the completion of the authentication.
-         */
-        active_state->rekey_time = monotime();
+        ssh->state->rekey_limit = bytes;
+        ssh->state->rekey_interval = seconds;
 }
 
 time_t
-packet_get_rekey_timeout(void)
+ssh_packet_get_rekey_timeout(struct ssh *ssh)
 {
         time_t seconds;
 
-        seconds = active_state->rekey_time + active_state->rekey_interval -
+        seconds = ssh->state->rekey_time + ssh->state->rekey_interval -
             monotime();
         return (seconds <= 0 ? 1 : seconds);
 }
 
 void
-packet_set_server(void)
+ssh_packet_set_server(struct ssh *ssh)
 {
-        active_state->server_side = 1;
+        ssh->state->server_side = 1;
 }
 
 void
-packet_set_authenticated(void)
-{
-        active_state->after_authentication = 1;
-}
-
-void *
-packet_get_input(void)
+ssh_packet_set_authenticated(struct ssh *ssh)
 {
-        return (void *)&active_state->input;
+        ssh->state->after_authentication = 1;
 }
 
 void *
-packet_get_output(void)
+ssh_packet_get_input(struct ssh *ssh)
 {
-        return (void *)&active_state->output;
+        return (void *)ssh->state->input;
 }
 
 void *
-packet_get_newkeys(int mode)
+ssh_packet_get_output(struct ssh *ssh)
 {
-        return (void *)active_state->newkeys[mode];
+        return (void *)ssh->state->output;
 }
 
+/* XXX TODO update roaming to new API (does not work anyway) */
 /*
  * Save the state for the real connection, and use a separate state when
  * resuming a suspended connection.
  */
 void
-packet_backup_state(void)
+ssh_packet_backup_state(struct ssh *ssh,
+    struct ssh *backup_state)
 {
-        struct session_state *tmp;
+        struct ssh *tmp;
 
-        close(active_state->connection_in);
-        active_state->connection_in = -1;
-        close(active_state->connection_out);
-        active_state->connection_out = -1;
+        close(ssh->state->connection_in);
+        ssh->state->connection_in = -1;
+        close(ssh->state->connection_out);
+        ssh->state->connection_out = -1;
         if (backup_state)
                 tmp = backup_state;
         else
-                tmp = alloc_session_state();
-        backup_state = active_state;
-        active_state = tmp;
+                tmp = ssh_alloc_session_state();
+        backup_state = ssh;
+        ssh = tmp;
 }
 
+/* XXX FIXME FIXME FIXME */
 /*
  * Swap in the old state when resuming a connecion.
  */
 void
-packet_restore_state(void)
+ssh_packet_restore_state(struct ssh *ssh,
+    struct ssh *backup_state)
 {
-        struct session_state *tmp;
-        void *buf;
+        struct ssh *tmp;
         u_int len;
+        int r;
 
         tmp = backup_state;
-        backup_state = active_state;
-        active_state = tmp;
-        active_state->connection_in = backup_state->connection_in;
-        backup_state->connection_in = -1;
-        active_state->connection_out = backup_state->connection_out;
-        backup_state->connection_out = -1;
-        len = buffer_len(&backup_state->input);
+        backup_state = ssh;
+        ssh = tmp;
+        ssh->state->connection_in = backup_state->state->connection_in;
+        backup_state->state->connection_in = -1;
+        ssh->state->connection_out = backup_state->state->connection_out;
+        backup_state->state->connection_out = -1;
+        len = sshbuf_len(backup_state->state->input);
         if (len > 0) {
-                buf = buffer_ptr(&backup_state->input);
-                buffer_append(&active_state->input, buf, len);
-                buffer_clear(&backup_state->input);
+                if ((r = sshbuf_putb(ssh->state->input,
+                    backup_state->state->input)) != 0)
+                        fatal("%s: %s", __func__, ssh_err(r));
+                sshbuf_reset(backup_state->state->input);
                 add_recv_bytes(len);
         }
 }
 
 /* Reset after_authentication and reset compression in post-auth privsep */
-void
-packet_set_postauth(void)
+static int
+ssh_packet_set_postauth(struct ssh *ssh)
 {
-        Comp *comp;
-        int mode;
+        struct sshcomp *comp;
+        int r, mode;
 
         debug("%s: called", __func__);
         /* This was set in net child, but is not visible in user child */
-        active_state->after_authentication = 1;
-        active_state->rekeying = 0;
+        ssh->state->after_authentication = 1;
+        ssh->state->rekeying = 0;
         for (mode = 0; mode < MODE_MAX; mode++) {
-                if (active_state->newkeys[mode] == NULL)
+                if (ssh->state->newkeys[mode] == NULL)
                         continue;
-                comp = &active_state->newkeys[mode]->comp;
-                if (comp && comp->enabled)
-                        packet_init_compression();
+                comp = &ssh->state->newkeys[mode]->comp;
+                if (comp && comp->enabled &&
+                    (r = ssh_packet_init_compression(ssh)) != 0)
+                        return r;
+        }
+        return 0;
+}
+
+/* Packet state (de-)serialization for privsep */
+
+/* turn kex into a blob for packet state serialization */
+static int
+kex_to_blob(struct sshbuf *m, struct kex *kex)
+{
+        int r;
+
+        if ((r = sshbuf_put_string(m, kex->session_id,
+            kex->session_id_len)) != 0 ||
+            (r = sshbuf_put_u32(m, kex->we_need)) != 0 ||
+            (r = sshbuf_put_u32(m, kex->hostkey_type)) != 0 ||
+            (r = sshbuf_put_u32(m, kex->kex_type)) != 0 ||
+            (r = sshbuf_put_stringb(m, kex->my)) != 0 ||
+            (r = sshbuf_put_stringb(m, kex->peer)) != 0 ||
+            (r = sshbuf_put_u32(m, kex->flags)) != 0 ||
+            (r = sshbuf_put_cstring(m, kex->client_version_string)) != 0 ||
+            (r = sshbuf_put_cstring(m, kex->server_version_string)) != 0)
+                return r;
+        return 0;
+}
+
+/* turn key exchange results into a blob for packet state serialization */
+static int
+newkeys_to_blob(struct sshbuf *m, struct ssh *ssh, int mode)
+{
+        struct sshbuf *b;
+        struct sshcipher_ctx *cc;
+        struct sshcomp *comp;
+        struct sshenc *enc;
+        struct sshmac *mac;
+        struct newkeys *newkey;
+        int r;
+
+        if ((newkey = ssh->state->newkeys[mode]) == NULL)
+                return SSH_ERR_INTERNAL_ERROR;
+        enc = &newkey->enc;
+        mac = &newkey->mac;
+        comp = &newkey->comp;
+        cc = (mode == MODE_OUT) ? &ssh->state->send_context :
+            &ssh->state->receive_context;
+        if ((r = cipher_get_keyiv(cc, enc->iv, enc->iv_len)) != 0)
+                return r;
+        if ((b = sshbuf_new()) == NULL)
+                return SSH_ERR_ALLOC_FAIL;
+        /* The cipher struct is constant and shared, you export pointer */
+        if ((r = sshbuf_put_cstring(b, enc->name)) != 0 ||
+            (r = sshbuf_put(b, &enc->cipher, sizeof(enc->cipher))) != 0 ||
+            (r = sshbuf_put_u32(b, enc->enabled)) != 0 ||
+            (r = sshbuf_put_u32(b, enc->block_size)) != 0 ||
+            (r = sshbuf_put_string(b, enc->key, enc->key_len)) != 0 ||
+            (r = sshbuf_put_string(b, enc->iv, enc->iv_len)) != 0)
+                goto out;
+        if (cipher_authlen(enc->cipher) == 0) {
+                if ((r = sshbuf_put_cstring(b, mac->name)) != 0 ||
+                    (r = sshbuf_put_u32(b, mac->enabled)) != 0 ||
+                    (r = sshbuf_put_string(b, mac->key, mac->key_len)) != 0)
+                        goto out;
+        }
+        if ((r = sshbuf_put_u32(b, comp->type)) != 0 ||
+            (r = sshbuf_put_u32(b, comp->enabled)) != 0 ||
+            (r = sshbuf_put_cstring(b, comp->name)) != 0)
+                goto out;
+        r = sshbuf_put_stringb(m, b);
+ out:
+        if (b != NULL)
+                sshbuf_free(b);
+        return r;
+}
+
+/* serialize packet state into a blob */
+int
+ssh_packet_get_state(struct ssh *ssh, struct sshbuf *m)
+{
+        struct session_state *state = ssh->state;
+        u_char *p;
+        size_t slen, rlen;
+        int r, ssh1cipher;
+
+        if (!compat20) {
+                ssh1cipher = cipher_get_number(state->receive_context.cipher);
+                slen = cipher_get_keyiv_len(&state->send_context);
+                rlen = cipher_get_keyiv_len(&state->receive_context);
+                if ((r = sshbuf_put_u32(m, state->remote_protocol_flags)) != 0 ||
+                    (r = sshbuf_put_u32(m, ssh1cipher)) != 0 ||
+                    (r = sshbuf_put_string(m, state->ssh1_key, state->ssh1_keylen)) != 0 ||
+                    (r = sshbuf_put_u32(m, slen)) != 0 ||
+                    (r = sshbuf_reserve(m, slen, &p)) != 0 ||
+                    (r = cipher_get_keyiv(&state->send_context, p, slen)) != 0 ||
+                    (r = sshbuf_put_u32(m, rlen)) != 0 ||
+                    (r = sshbuf_reserve(m, rlen, &p)) != 0 ||
+                    (r = cipher_get_keyiv(&state->receive_context, p, rlen)) != 0)
+                        return r;
+        } else {
+                if ((r = kex_to_blob(m, ssh->kex)) != 0 ||
+                    (r = newkeys_to_blob(m, ssh, MODE_OUT)) != 0 ||
+                    (r = newkeys_to_blob(m, ssh, MODE_IN)) != 0 ||
+                    (r = sshbuf_put_u32(m, state->rekey_limit)) != 0 ||
+                    (r = sshbuf_put_u32(m, state->rekey_interval)) != 0 ||
+                    (r = sshbuf_put_u32(m, state->p_send.seqnr)) != 0 ||
+                    (r = sshbuf_put_u64(m, state->p_send.blocks)) != 0 ||
+                    (r = sshbuf_put_u32(m, state->p_send.packets)) != 0 ||
+                    (r = sshbuf_put_u64(m, state->p_send.bytes)) != 0 ||
+                    (r = sshbuf_put_u32(m, state->p_read.seqnr)) != 0 ||
+                    (r = sshbuf_put_u64(m, state->p_read.blocks)) != 0 ||
+                    (r = sshbuf_put_u32(m, state->p_read.packets)) != 0 ||
+                    (r = sshbuf_put_u64(m, state->p_read.bytes)) != 0)
+                        return r;
+        }
+
+        slen = cipher_get_keycontext(&state->send_context, NULL);
+        rlen = cipher_get_keycontext(&state->receive_context, NULL);
+        if ((r = sshbuf_put_u32(m, slen)) != 0 ||
+            (r = sshbuf_reserve(m, slen, &p)) != 0)
+                return r;
+        if (cipher_get_keycontext(&state->send_context, p) != (int)slen)
+                return SSH_ERR_INTERNAL_ERROR;
+        if ((r = sshbuf_put_u32(m, rlen)) != 0 ||
+            (r = sshbuf_reserve(m, rlen, &p)) != 0)
+                return r;
+        if (cipher_get_keycontext(&state->receive_context, p) != (int)rlen)
+                return SSH_ERR_INTERNAL_ERROR;
+
+        if ((r = ssh_packet_get_compress_state(m, ssh)) != 0 ||
+            (r = sshbuf_put_stringb(m, state->input)) != 0 ||
+            (r = sshbuf_put_stringb(m, state->output)) != 0)
+                return r;
+
+        if (compat20) {
+                if ((r = sshbuf_put_u64(m, get_sent_bytes())) != 0 ||
+                    (r = sshbuf_put_u64(m, get_recv_bytes())) != 0)
+                        return r;
+        }
+        return 0;
+}
+
+/* restore key exchange results from blob for packet state de-serialization */
+static int
+newkeys_from_blob(struct sshbuf *m, struct ssh *ssh, int mode)
+{
+        struct sshbuf *b = NULL;
+        struct sshcomp *comp;
+        struct sshenc *enc;
+        struct sshmac *mac;
+        struct newkeys *newkey = NULL;
+        size_t keylen, ivlen, maclen;
+        int r;
+
+        if ((newkey = calloc(1, sizeof(*newkey))) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        if ((r = sshbuf_froms(m, &b)) != 0)
+                goto out;
+#ifdef DEBUG_PK
+        sshbuf_dump(b, stderr);
+#endif
+        enc = &newkey->enc;
+        mac = &newkey->mac;
+        comp = &newkey->comp;
+
+        if ((r = sshbuf_get_cstring(b, &enc->name, NULL)) != 0 ||
+            (r = sshbuf_get(b, &enc->cipher, sizeof(enc->cipher))) != 0 ||
+            (r = sshbuf_get_u32(b, (u_int *)&enc->enabled)) != 0 ||
+            (r = sshbuf_get_u32(b, &enc->block_size)) != 0 ||
+            (r = sshbuf_get_string(b, &enc->key, &keylen)) != 0 ||
+            (r = sshbuf_get_string(b, &enc->iv, &ivlen)) != 0)
+                goto out;
+        if (cipher_authlen(enc->cipher) == 0) {
+                if ((r = sshbuf_get_cstring(b, &mac->name, NULL)) != 0)
+                        goto out;
+                if ((r = mac_setup(mac, mac->name)) != 0)
+                        goto out;
+                if ((r = sshbuf_get_u32(b, (u_int *)&mac->enabled)) != 0 ||
+                    (r = sshbuf_get_string(b, &mac->key, &maclen)) != 0)
+                        goto out;
+                if (maclen > mac->key_len) {
+                        r = SSH_ERR_INVALID_FORMAT;
+                        goto out;
+                }
+                mac->key_len = maclen;
+        }
+        if ((r = sshbuf_get_u32(b, &comp->type)) != 0 ||
+            (r = sshbuf_get_u32(b, (u_int *)&comp->enabled)) != 0 ||
+            (r = sshbuf_get_cstring(b, &comp->name, NULL)) != 0)
+                goto out;
+        if (enc->name == NULL ||
+            cipher_by_name(enc->name) != enc->cipher) {
+                r = SSH_ERR_INVALID_FORMAT;
+                goto out;
+        }
+        if (sshbuf_len(b) != 0) {
+                r = SSH_ERR_INVALID_FORMAT;
+                goto out;
+        }
+        enc->key_len = keylen;
+        enc->iv_len = ivlen;
+        ssh->kex->newkeys[mode] = newkey;
+        newkey = NULL;
+        r = 0;
+ out:
+        if (newkey != NULL)
+                free(newkey);
+        if (b != NULL)
+                sshbuf_free(b);
+        return r;
+}
+
+/* restore kex from blob for packet state de-serialization */
+static int
+kex_from_blob(struct sshbuf *m, struct kex **kexp)
+{
+        struct kex *kex;
+        int r;
+
+        if ((kex = calloc(1, sizeof(struct kex))) == NULL ||
+            (kex->my = sshbuf_new()) == NULL ||
+            (kex->peer = sshbuf_new()) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        if ((r = sshbuf_get_string(m, &kex->session_id, &kex->session_id_len)) != 0 ||
+            (r = sshbuf_get_u32(m, &kex->we_need)) != 0 ||
+            (r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_type)) != 0 ||
+            (r = sshbuf_get_u32(m, &kex->kex_type)) != 0 ||
+            (r = sshbuf_get_stringb(m, kex->my)) != 0 ||
+            (r = sshbuf_get_stringb(m, kex->peer)) != 0 ||
+            (r = sshbuf_get_u32(m, &kex->flags)) != 0 ||
+            (r = sshbuf_get_cstring(m, &kex->client_version_string, NULL)) != 0 ||
+            (r = sshbuf_get_cstring(m, &kex->server_version_string, NULL)) != 0)
+                goto out;
+        kex->server = 1;
+        kex->done = 1;
+        r = 0;
+ out:
+        if (r != 0 || kexp == NULL) {
+                if (kex != NULL) {
+                        if (kex->my != NULL)
+                                sshbuf_free(kex->my);
+                        if (kex->peer != NULL)
+                                sshbuf_free(kex->peer);
+                        free(kex);
+                }
+                if (kexp != NULL)
+                        *kexp = NULL;
+        } else {
+                *kexp = kex;
+        }
+        return r;
+}
+
+/*
+ * Restore packet state from content of blob 'm' (de-serialization).
+ * Note that 'm' will be partially consumed on parsing or any other errors.
+ */
+int
+ssh_packet_set_state(struct ssh *ssh, struct sshbuf *m)
+{
+        struct session_state *state = ssh->state;
+        const u_char *ssh1key, *ivin, *ivout, *keyin, *keyout, *input, *output;
+        size_t ssh1keylen, rlen, slen, ilen, olen;
+        int r;
+        u_int ssh1cipher = 0;
+        u_int64_t sent_bytes = 0, recv_bytes = 0;
+
+        if (!compat20) {
+                if ((r = sshbuf_get_u32(m, &state->remote_protocol_flags)) != 0 ||
+                    (r = sshbuf_get_u32(m, &ssh1cipher)) != 0 ||
+                    (r = sshbuf_get_string_direct(m, &ssh1key, &ssh1keylen)) != 0 ||
+                    (r = sshbuf_get_string_direct(m, &ivout, &slen)) != 0 ||
+                    (r = sshbuf_get_string_direct(m, &ivin, &rlen)) != 0)
+                        return r;
+                if (ssh1cipher > INT_MAX)
+                        return SSH_ERR_KEY_UNKNOWN_CIPHER;
+                ssh_packet_set_encryption_key(ssh, ssh1key, ssh1keylen,
+                    (int)ssh1cipher);
+                if (cipher_get_keyiv_len(&state->send_context) != (int)slen ||
+                    cipher_get_keyiv_len(&state->receive_context) != (int)rlen)
+                        return SSH_ERR_INVALID_FORMAT;
+                if ((r = cipher_set_keyiv(&state->send_context, ivout)) != 0 ||
+                    (r = cipher_set_keyiv(&state->receive_context, ivin)) != 0)
+                        return r;
+        } else {
+                if ((r = kex_from_blob(m, &ssh->kex)) != 0 ||
+                    (r = newkeys_from_blob(m, ssh, MODE_OUT)) != 0 ||
+                    (r = newkeys_from_blob(m, ssh, MODE_IN)) != 0 ||
+                    (r = sshbuf_get_u32(m, &state->rekey_limit)) != 0 ||
+                    (r = sshbuf_get_u32(m, &state->rekey_interval)) != 0 ||
+                    (r = sshbuf_get_u32(m, &state->p_send.seqnr)) != 0 ||
+                    (r = sshbuf_get_u64(m, &state->p_send.blocks)) != 0 ||
+                    (r = sshbuf_get_u32(m, &state->p_send.packets)) != 0 ||
+                    (r = sshbuf_get_u64(m, &state->p_send.bytes)) != 0 ||
+                    (r = sshbuf_get_u32(m, &state->p_read.seqnr)) != 0 ||
+                    (r = sshbuf_get_u64(m, &state->p_read.blocks)) != 0 ||
+                    (r = sshbuf_get_u32(m, &state->p_read.packets)) != 0 ||
+                    (r = sshbuf_get_u64(m, &state->p_read.bytes)) != 0)
+                        return r;
+                /*
+                 * We set the time here so that in post-auth privsep slave we
+                 * count from the completion of the authentication.
+                 */
+                state->rekey_time = monotime();
+                /* XXX ssh_set_newkeys overrides p_read.packets? XXX */
+                if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0 ||
+                    (r = ssh_set_newkeys(ssh, MODE_OUT)) != 0)
+                        return r;
+        }
+        if ((r = sshbuf_get_string_direct(m, &keyout, &slen)) != 0 ||
+            (r = sshbuf_get_string_direct(m, &keyin, &rlen)) != 0)
+                return r;
+        if (cipher_get_keycontext(&state->send_context, NULL) != (int)slen ||
+            cipher_get_keycontext(&state->receive_context, NULL) != (int)rlen)
+                return SSH_ERR_INVALID_FORMAT;
+        cipher_set_keycontext(&state->send_context, keyout);
+        cipher_set_keycontext(&state->receive_context, keyin);
+
+        if ((r = ssh_packet_set_compress_state(ssh, m)) != 0 ||
+            (r = ssh_packet_set_postauth(ssh)) != 0)
+                return r;
+
+        sshbuf_reset(state->input);
+        sshbuf_reset(state->output);
+        if ((r = sshbuf_get_string_direct(m, &input, &ilen)) != 0 ||
+            (r = sshbuf_get_string_direct(m, &output, &olen)) != 0 ||
+            (r = sshbuf_put(state->input, input, ilen)) != 0 ||
+            (r = sshbuf_put(state->output, output, olen)) != 0)
+                return r;
+
+        if (compat20) {
+                if ((r = sshbuf_get_u64(m, &sent_bytes)) != 0 ||
+                    (r = sshbuf_get_u64(m, &recv_bytes)) != 0)
+                        return r;
+                roam_set_bytes(sent_bytes, recv_bytes);
         }
+        if (sshbuf_len(m))
+                return SSH_ERR_INVALID_FORMAT;
+        debug3("%s: done", __func__);
+        return 0;
+}
+
+/* NEW API */
+
+/* put data to the outgoing packet */
+
+int
+sshpkt_put(struct ssh *ssh, const void *v, size_t len)
+{
+        return sshbuf_put(ssh->state->outgoing_packet, v, len);
+}
+
+int
+sshpkt_putb(struct ssh *ssh, const struct sshbuf *b)
+{
+        return sshbuf_putb(ssh->state->outgoing_packet, b);
+}
+
+int
+sshpkt_put_u8(struct ssh *ssh, u_char val)
+{
+        return sshbuf_put_u8(ssh->state->outgoing_packet, val);
+}
+
+int
+sshpkt_put_u32(struct ssh *ssh, u_int32_t val)
+{
+        return sshbuf_put_u32(ssh->state->outgoing_packet, val);
+}
+
+int
+sshpkt_put_u64(struct ssh *ssh, u_int64_t val)
+{
+        return sshbuf_put_u64(ssh->state->outgoing_packet, val);
+}
+
+int
+sshpkt_put_string(struct ssh *ssh, const void *v, size_t len)
+{
+        return sshbuf_put_string(ssh->state->outgoing_packet, v, len);
+}
+
+int
+sshpkt_put_cstring(struct ssh *ssh, const void *v)
+{
+        return sshbuf_put_cstring(ssh->state->outgoing_packet, v);
+}
+
+int
+sshpkt_put_stringb(struct ssh *ssh, const struct sshbuf *v)
+{
+        return sshbuf_put_stringb(ssh->state->outgoing_packet, v);
+}
+
+#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
+int
+sshpkt_put_ec(struct ssh *ssh, const EC_POINT *v, const EC_GROUP *g)
+{
+        return sshbuf_put_ec(ssh->state->outgoing_packet, v, g);
+}
+#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */
+
+#ifdef WITH_SSH1
+int
+sshpkt_put_bignum1(struct ssh *ssh, const BIGNUM *v)
+{
+        return sshbuf_put_bignum1(ssh->state->outgoing_packet, v);
+}
+#endif /* WITH_SSH1 */
+
+#ifdef WITH_OPENSSL
+int
+sshpkt_put_bignum2(struct ssh *ssh, const BIGNUM *v)
+{
+        return sshbuf_put_bignum2(ssh->state->outgoing_packet, v);
+}
+#endif /* WITH_OPENSSL */
+
+/* fetch data from the incoming packet */
+
+int
+sshpkt_get(struct ssh *ssh, void *valp, size_t len)
+{
+        return sshbuf_get(ssh->state->incoming_packet, valp, len);
+}
+
+int
+sshpkt_get_u8(struct ssh *ssh, u_char *valp)
+{
+        return sshbuf_get_u8(ssh->state->incoming_packet, valp);
+}
+
+int
+sshpkt_get_u32(struct ssh *ssh, u_int32_t *valp)
+{
+        return sshbuf_get_u32(ssh->state->incoming_packet, valp);
+}
+
+int
+sshpkt_get_u64(struct ssh *ssh, u_int64_t *valp)
+{
+        return sshbuf_get_u64(ssh->state->incoming_packet, valp);
+}
+
+int
+sshpkt_get_string(struct ssh *ssh, u_char **valp, size_t *lenp)
+{
+        return sshbuf_get_string(ssh->state->incoming_packet, valp, lenp);
+}
+
+int
+sshpkt_get_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp)
+{
+        return sshbuf_get_string_direct(ssh->state->incoming_packet, valp, lenp);
+}
+
+int
+sshpkt_get_cstring(struct ssh *ssh, char **valp, size_t *lenp)
+{
+        return sshbuf_get_cstring(ssh->state->incoming_packet, valp, lenp);
+}
+
+#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
+int
+sshpkt_get_ec(struct ssh *ssh, EC_POINT *v, const EC_GROUP *g)
+{
+        return sshbuf_get_ec(ssh->state->incoming_packet, v, g);
+}
+#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */
+
+#ifdef WITH_SSH1
+int
+sshpkt_get_bignum1(struct ssh *ssh, BIGNUM *v)
+{
+        return sshbuf_get_bignum1(ssh->state->incoming_packet, v);
+}
+#endif /* WITH_SSH1 */
+
+#ifdef WITH_OPENSSL
+int
+sshpkt_get_bignum2(struct ssh *ssh, BIGNUM *v)
+{
+        return sshbuf_get_bignum2(ssh->state->incoming_packet, v);
+}
+#endif /* WITH_OPENSSL */
+
+int
+sshpkt_get_end(struct ssh *ssh)
+{
+        if (sshbuf_len(ssh->state->incoming_packet) > 0)
+                return SSH_ERR_UNEXPECTED_TRAILING_DATA;
+        return 0;
+}
+
+const u_char *
+sshpkt_ptr(struct ssh *ssh, size_t *lenp)
+{
+        if (lenp != NULL)
+                *lenp = sshbuf_len(ssh->state->incoming_packet);
+        return sshbuf_ptr(ssh->state->incoming_packet);
+}
+
+/* start a new packet */
+
+int
+sshpkt_start(struct ssh *ssh, u_char type)
+{
+        u_char buf[9];
+        int len;
+
+        DBG(debug("packet_start[%d]", type));
+        len = compat20 ? 6 : 9;
+        memset(buf, 0, len - 1);
+        buf[len - 1] = type;
+        sshbuf_reset(ssh->state->outgoing_packet);
+        return sshbuf_put(ssh->state->outgoing_packet, buf, len);
+}
+
+/* send it */
+
+int
+sshpkt_send(struct ssh *ssh)
+{
+        if (compat20)
+                return ssh_packet_send2(ssh);
+        else
+                return ssh_packet_send1(ssh);
+}
+
+int
+sshpkt_disconnect(struct ssh *ssh, const char *fmt,...)
+{
+        char buf[1024];
+        va_list args;
+        int r;
+
+        va_start(args, fmt);
+        vsnprintf(buf, sizeof(buf), fmt, args);
+        va_end(args);
+
+        if (compat20) {
+                if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_PROTOCOL_ERROR)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0)
+                        return r;
+        } else {
+                if ((r = sshpkt_start(ssh, SSH_MSG_DISCONNECT)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0)
+                        return r;
+        }
+        return 0;
+}
+
+/* roundup current message to pad bytes */
+int
+sshpkt_add_padding(struct ssh *ssh, u_char pad)
+{
+        ssh->state->extra_pad = pad;
+        return 0;
 }