1 files changed, 572 insertions, 401 deletions

diff --git a/packet.c b/packet.c
index 5afc84ce0..994e35b6d 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.160 2009/02/13 11:50:21 markus Exp $ */
+/* $OpenBSD: packet.c,v 1.166 2009/06/27 09:29:06 andreas Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -77,6 +77,7 @@
 #include "canohost.h"
 #include "misc.h"
 #include "ssh.h"
+#include "roaming.h"
 
 #ifdef PACKET_DEBUG
 #define DBG(x) x
@@ -86,92 +87,126 @@
 
 #define PACKET_MAX_SIZE (256 * 1024)
 
-/*
- * This variable contains the file descriptors used for communicating with
- * the other side.  connection_in is used for reading; connection_out for
- * writing.  These can be the same descriptor, in which case it is assumed to
- * be a socket.
- */
-static int connection_in = -1;
-static int connection_out = -1;
+struct packet_state {
+        u_int32_t seqnr;
+        u_int32_t packets;
+        u_int64_t blocks;
+        u_int64_t bytes;
+};
 
-/* Protocol flags for the remote side. */
-static u_int remote_protocol_flags = 0;
+struct packet {
+        TAILQ_ENTRY(packet) next;
+        u_char type;
+        Buffer payload;
+};
 
-/* Encryption context for receiving data.  This is only used for decryption. */
-static CipherContext receive_context;
+struct session_state {
+        /*
+         * This variable contains the file descriptors used for
+         * communicating with the other side.  connection_in is used for
+         * reading; connection_out for writing.  These can be the same
+         * descriptor, in which case it is assumed to be a socket.
+         */
+        int connection_in;
+        int connection_out;
 
-/* Encryption context for sending data.  This is only used for encryption. */
-static CipherContext send_context;
+        /* Protocol flags for the remote side. */
+        u_int remote_protocol_flags;
 
-/* Buffer for raw input data from the socket. */
-Buffer input;
+        /* Encryption context for receiving data.  Only used for decryption. */
+        CipherContext receive_context;
 
-/* Buffer for raw output data going to the socket. */
-Buffer output;
+        /* Encryption context for sending data.  Only used for encryption. */
+        CipherContext send_context;
 
-/* Buffer for the partial outgoing packet being constructed. */
-static Buffer outgoing_packet;
+        /* Buffer for raw input data from the socket. */
+        Buffer input;
 
-/* Buffer for the incoming packet currently being processed. */
-static Buffer incoming_packet;
+        /* Buffer for raw output data going to the socket. */
+        Buffer output;
 
-/* Scratch buffer for packet compression/decompression. */
-static Buffer compression_buffer;
-static int compression_buffer_ready = 0;
+        /* Buffer for the partial outgoing packet being constructed. */
+        Buffer outgoing_packet;
 
-/* Flag indicating whether packet compression/decompression is enabled. */
-static int packet_compression = 0;
+        /* Buffer for the incoming packet currently being processed. */
+        Buffer incoming_packet;
 
-/* default maximum packet size */
-u_int max_packet_size = 32768;
+        /* Scratch buffer for packet compression/decompression. */
+        Buffer compression_buffer;
+        int compression_buffer_ready;
 
-/* Flag indicating whether this module has been initialized. */
-static int initialized = 0;
+        /*
+         * Flag indicating whether packet compression/decompression is
+         * enabled.
+         */
+        int packet_compression;
 
-/* Set to true if the connection is interactive. */
-static int interactive_mode = 0;
+        /* default maximum packet size */
+        u_int max_packet_size;
 
-/* Set to true if we are the server side. */
-static int server_side = 0;
+        /* Flag indicating whether this module has been initialized. */
+        int initialized;
 
-/* Set to true if we are authenticated. */
-static int after_authentication = 0;
+        /* Set to true if the connection is interactive. */
+        int interactive_mode;
 
-int keep_alive_timeouts = 0;
+        /* Set to true if we are the server side. */
+        int server_side;
 
-/* Set to the maximum time that we will wait to send or receive a packet */
-static int packet_timeout_ms = -1;
+        /* Set to true if we are authenticated. */
+        int after_authentication;
 
-/* Session key information for Encryption and MAC */
-Newkeys *newkeys[MODE_MAX];
-static struct packet_state {
-        u_int32_t seqnr;
-        u_int32_t packets;
-        u_int64_t blocks;
-        u_int64_t bytes;
-} p_read, p_send;
+        int keep_alive_timeouts;
 
-static u_int64_t max_blocks_in, max_blocks_out;
-static u_int32_t rekey_limit;
+        /* The maximum time that we will wait to send or receive a packet */
+        int packet_timeout_ms;
 
-/* Session key for protocol v1 */
-static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
-static u_int ssh1_keylen;
+        /* Session key information for Encryption and MAC */
+        Newkeys *newkeys[MODE_MAX];
+        struct packet_state p_read, p_send;
 
-/* roundup current message to extra_pad bytes */
-static u_char extra_pad = 0;
+        u_int64_t max_blocks_in, max_blocks_out;
+        u_int32_t rekey_limit;
 
-/* XXX discard incoming data after MAC error */
-static u_int packet_discard = 0;
-static Mac *packet_discard_mac = NULL;
+        /* Session key for protocol v1 */
+        u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
+        u_int ssh1_keylen;
 
-struct packet {
-        TAILQ_ENTRY(packet) next;
-        u_char type;
-        Buffer payload;
+        /* roundup current message to extra_pad bytes */
+        u_char extra_pad;
+
+        /* XXX discard incoming data after MAC error */
+        u_int packet_discard;
+        Mac *packet_discard_mac;
+
+        /* Used in packet_read_poll2() */
+        u_int packlen;
+
+        /* Used in packet_send2 */
+        int rekeying;
+
+        /* Used in packet_set_interactive */
+        int set_interactive_called;
+
+        /* Used in packet_set_maxsize */
+        int set_maxsize_called;
+
+        TAILQ_HEAD(, packet) outgoing;
 };
-TAILQ_HEAD(, packet) outgoing;
+
+static struct session_state *active_state, *backup_state;
+
+static struct session_state *
+alloc_session_state(void)
+{
+    struct session_state *s = xcalloc(1, sizeof(*s));
+
+    s->connection_in = -1;
+    s->connection_out = -1;
+    s->max_packet_size = 32768;
+    s->packet_timeout_ms = -1;
+    return s;
+}
 
 /*
  * Sets the descriptors used for communication.  Disables encryption until
@@ -184,21 +219,23 @@ packet_set_connection(int fd_in, int fd_out)
 
         if (none == NULL)
                 fatal("packet_set_connection: cannot load cipher 'none'");
-        connection_in = fd_in;
-        connection_out = fd_out;
-        cipher_init(&send_context, none, (const u_char *)"",
+        if (active_state == NULL)
+                active_state = alloc_session_state();
+        active_state->connection_in = fd_in;
+        active_state->connection_out = fd_out;
+        cipher_init(&active_state->send_context, none, (const u_char *)"",
             0, NULL, 0, CIPHER_ENCRYPT);
-        cipher_init(&receive_context, none, (const u_char *)"",
+        cipher_init(&active_state->receive_context, none, (const u_char *)"",
             0, NULL, 0, CIPHER_DECRYPT);
-        newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
-        if (!initialized) {
-                initialized = 1;
-                buffer_init(&input);
-                buffer_init(&output);
-                buffer_init(&outgoing_packet);
-                buffer_init(&incoming_packet);
-                TAILQ_INIT(&outgoing);
-                p_send.packets = p_read.packets = 0;
+        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;
         }
 }
 
@@ -206,27 +243,29 @@ void
 packet_set_timeout(int timeout, int count)
 {
         if (timeout == 0 || count == 0) {
-                packet_timeout_ms = -1;
+                active_state->packet_timeout_ms = -1;
                 return;
         }
         if ((INT_MAX / 1000) / count < timeout)
-                packet_timeout_ms = INT_MAX;
+                active_state->packet_timeout_ms = INT_MAX;
         else
-                packet_timeout_ms = timeout * count * 1000;
+                active_state->packet_timeout_ms = timeout * count * 1000;
 }
 
 static void
 packet_stop_discard(void)
 {
-        if (packet_discard_mac) {
+        if (active_state->packet_discard_mac) {
                 char buf[1024];
                 
                 memset(buf, 'a', sizeof(buf));
-                while (buffer_len(&incoming_packet) < PACKET_MAX_SIZE)
-                        buffer_append(&incoming_packet, buf, sizeof(buf));
-                (void) mac_compute(packet_discard_mac,
-                    p_read.seqnr,
-                    buffer_ptr(&incoming_packet),
+                while (buffer_len(&active_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());
@@ -239,10 +278,11 @@ packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
         if (enc == NULL || !cipher_is_cbc(enc->cipher))
                 packet_disconnect("Packet corrupt");
         if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
-                packet_discard_mac = mac;
-        if (buffer_len(&input) >= discard)
+                active_state->packet_discard_mac = mac;
+        if (buffer_len(&active_state->input) >= discard)
                 packet_stop_discard();
-        packet_discard = discard - buffer_len(&input);
+        active_state->packet_discard = discard -
+            buffer_len(&active_state->input);
 }
 
 /* Returns 1 if remote host is connected via socket, 0 if not. */
@@ -254,15 +294,17 @@ packet_connection_is_on_socket(void)
         socklen_t fromlen, tolen;
 
         /* filedescriptors in and out are the same, so it's a socket */
-        if (connection_in == connection_out)
+        if (active_state->connection_in == active_state->connection_out)
                 return 1;
         fromlen = sizeof(from);
         memset(&from, 0, sizeof(from));
-        if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
+        if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
+            &fromlen) < 0)
                 return 0;
         tolen = sizeof(to);
         memset(&to, 0, sizeof(to));
-        if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
+        if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
+            &tolen) < 0)
                 return 0;
         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
                 return 0;
@@ -283,9 +325,9 @@ packet_get_keyiv(int mode, u_char *iv, u_int len)
         CipherContext *cc;
 
         if (mode == MODE_OUT)
-                cc = &send_context;
+                cc = &active_state->send_context;
         else
-                cc = &receive_context;
+                cc = &active_state->receive_context;
 
         cipher_get_keyiv(cc, iv, len);
 }
@@ -296,9 +338,9 @@ packet_get_keycontext(int mode, u_char *dat)
         CipherContext *cc;
 
         if (mode == MODE_OUT)
-                cc = &send_context;
+                cc = &active_state->send_context;
         else
-                cc = &receive_context;
+                cc = &active_state->receive_context;
 
         return (cipher_get_keycontext(cc, dat));
 }
@@ -309,9 +351,9 @@ packet_set_keycontext(int mode, u_char *dat)
         CipherContext *cc;
 
         if (mode == MODE_OUT)
-                cc = &send_context;
+                cc = &active_state->send_context;
         else
-                cc = &receive_context;
+                cc = &active_state->receive_context;
 
         cipher_set_keycontext(cc, dat);
 }
@@ -322,9 +364,9 @@ packet_get_keyiv_len(int mode)
         CipherContext *cc;
 
         if (mode == MODE_OUT)
-                cc = &send_context;
+                cc = &active_state->send_context;
         else
-                cc = &receive_context;
+                cc = &active_state->receive_context;
 
         return (cipher_get_keyiv_len(cc));
 }
@@ -335,9 +377,9 @@ packet_set_iv(int mode, u_char *dat)
         CipherContext *cc;
 
         if (mode == MODE_OUT)
-                cc = &send_context;
+                cc = &active_state->send_context;
         else
-                cc = &receive_context;
+                cc = &active_state->receive_context;
 
         cipher_set_keyiv(cc, dat);
 }
@@ -345,7 +387,7 @@ packet_set_iv(int mode, u_char *dat)
 int
 packet_get_ssh1_cipher(void)
 {
-        return (cipher_get_number(receive_context.cipher));
+        return (cipher_get_number(active_state->receive_context.cipher));
 }
 
 void
@@ -354,7 +396,8 @@ packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packe
 {
         struct packet_state *state;
 
-        state = (mode == MODE_IN) ? &p_read : &p_send;
+        state = (mode == MODE_IN) ?
+            &active_state->p_read : &active_state->p_send;
         if (seqnr)
                 *seqnr = state->seqnr;
         if (blocks)
@@ -371,7 +414,8 @@ packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
 {
         struct packet_state *state;
 
-        state = (mode == MODE_IN) ? &p_read : &p_send;
+        state = (mode == MODE_IN) ?
+            &active_state->p_read : &active_state->p_send;
         state->seqnr = seqnr;
         state->blocks = blocks;
         state->packets = packets;
@@ -387,7 +431,8 @@ packet_connection_is_ipv4(void)
         socklen_t tolen = sizeof(to);
 
         memset(&to, 0, sizeof(to));
-        if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
+        if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
+            &tolen) < 0)
                 return 0;
         if (to.ss_family == AF_INET)
                 return 1;
@@ -405,10 +450,10 @@ void
 packet_set_nonblocking(void)
 {
         /* Set the socket into non-blocking mode. */
-        set_nonblock(connection_in);
+        set_nonblock(active_state->connection_in);
 
-        if (connection_out != connection_in)
-                set_nonblock(connection_out);
+        if (active_state->connection_out != active_state->connection_in)
+                set_nonblock(active_state->connection_out);
 }
 
 /* Returns the socket used for reading. */
@@ -416,7 +461,7 @@ packet_set_nonblocking(void)
 int
 packet_get_connection_in(void)
 {
-        return connection_in;
+        return active_state->connection_in;
 }
 
 /* Returns the descriptor used for writing. */
@@ -424,7 +469,7 @@ packet_get_connection_in(void)
 int
 packet_get_connection_out(void)
 {
-        return connection_out;
+        return active_state->connection_out;
 }
 
 /* Closes the connection and clears and frees internal data structures. */
@@ -432,26 +477,26 @@ packet_get_connection_out(void)
 void
 packet_close(void)
 {
-        if (!initialized)
+        if (!active_state->initialized)
                 return;
-        initialized = 0;
-        if (connection_in == connection_out) {
-                shutdown(connection_out, SHUT_RDWR);
-                close(connection_out);
+        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);
         } else {
-                close(connection_in);
-                close(connection_out);
+                close(active_state->connection_in);
+                close(active_state->connection_out);
         }
-        buffer_free(&input);
-        buffer_free(&output);
-        buffer_free(&outgoing_packet);
-        buffer_free(&incoming_packet);
-        if (compression_buffer_ready) {
-                buffer_free(&compression_buffer);
+        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();
         }
-        cipher_cleanup(&send_context);
-        cipher_cleanup(&receive_context);
+        cipher_cleanup(&active_state->send_context);
+        cipher_cleanup(&active_state->receive_context);
 }
 
 /* Sets remote side protocol flags. */
@@ -459,7 +504,7 @@ packet_close(void)
 void
 packet_set_protocol_flags(u_int protocol_flags)
 {
-        remote_protocol_flags = protocol_flags;
+        active_state->remote_protocol_flags = protocol_flags;
 }
 
 /* Returns the remote protocol flags set earlier by the above function. */
@@ -467,7 +512,7 @@ packet_set_protocol_flags(u_int protocol_flags)
 u_int
 packet_get_protocol_flags(void)
 {
-        return remote_protocol_flags;
+        return active_state->remote_protocol_flags;
 }
 
 /*
@@ -478,18 +523,18 @@ packet_get_protocol_flags(void)
 static void
 packet_init_compression(void)
 {
-        if (compression_buffer_ready == 1)
+        if (active_state->compression_buffer_ready == 1)
                 return;
-        compression_buffer_ready = 1;
-        buffer_init(&compression_buffer);
+        active_state->compression_buffer_ready = 1;
+        buffer_init(&active_state->compression_buffer);
 }
 
 void
 packet_start_compression(int level)
 {
-        if (packet_compression && !compat20)
+        if (active_state->packet_compression && !compat20)
                 fatal("Compression already enabled.");
-        packet_compression = 1;
+        active_state->packet_compression = 1;
         packet_init_compression();
         buffer_compress_init_send(level);
         buffer_compress_init_recv();
@@ -513,19 +558,21 @@ packet_set_encryption_key(const u_char *key, u_int keylen,
                 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(ssh1_key, key, keylen);
-        ssh1_keylen = keylen;
-        cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
-        cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
+        memcpy(active_state->ssh1_key, key, keylen);
+        active_state->ssh1_keylen = keylen;
+        cipher_init(&active_state->send_context, cipher, key, keylen, NULL,
+            0, CIPHER_ENCRYPT);
+        cipher_init(&active_state->receive_context, cipher, key, keylen, NULL,
+            0, CIPHER_DECRYPT);
 }
 
 u_int
 packet_get_encryption_key(u_char *key)
 {
         if (key == NULL)
-                return (ssh1_keylen);
-        memcpy(key, ssh1_key, ssh1_keylen);
-        return (ssh1_keylen);
+                return (active_state->ssh1_keylen);
+        memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
+        return (active_state->ssh1_keylen);
 }
 
 /* Start constructing a packet to send. */
@@ -539,8 +586,8 @@ packet_start(u_char type)
         len = compat20 ? 6 : 9;
         memset(buf, 0, len - 1);
         buf[len - 1] = type;
-        buffer_clear(&outgoing_packet);
-        buffer_append(&outgoing_packet, buf, len);
+        buffer_clear(&active_state->outgoing_packet);
+        buffer_append(&active_state->outgoing_packet, buf, len);
 }
 
 /* Append payload. */
@@ -549,43 +596,49 @@ packet_put_char(int value)
 {
         char ch = value;
 
-        buffer_append(&outgoing_packet, &ch, 1);
+        buffer_append(&active_state->outgoing_packet, &ch, 1);
 }
 
 void
 packet_put_int(u_int value)
 {
-        buffer_put_int(&outgoing_packet, value);
+        buffer_put_int(&active_state->outgoing_packet, value);
+}
+
+void
+packet_put_int64(u_int64_t value)
+{
+        buffer_put_int64(&active_state->outgoing_packet, value);
 }
 
 void
 packet_put_string(const void *buf, u_int len)
 {
-        buffer_put_string(&outgoing_packet, buf, len);
+        buffer_put_string(&active_state->outgoing_packet, buf, len);
 }
 
 void
 packet_put_cstring(const char *str)
 {
-        buffer_put_cstring(&outgoing_packet, str);
+        buffer_put_cstring(&active_state->outgoing_packet, str);
 }
 
 void
 packet_put_raw(const void *buf, u_int len)
 {
-        buffer_append(&outgoing_packet, buf, len);
+        buffer_append(&active_state->outgoing_packet, buf, len);
 }
 
 void
 packet_put_bignum(BIGNUM * value)
 {
-        buffer_put_bignum(&outgoing_packet, value);
+        buffer_put_bignum(&active_state->outgoing_packet, value);
 }
 
 void
 packet_put_bignum2(BIGNUM * value)
 {
-        buffer_put_bignum2(&outgoing_packet, value);
+        buffer_put_bignum2(&active_state->outgoing_packet, value);
 }
 
 /*
@@ -605,24 +658,27 @@ packet_send1(void)
          * If using packet compression, compress the payload of the outgoing
          * packet.
          */
-        if (packet_compression) {
-                buffer_clear(&compression_buffer);
+        if (active_state->packet_compression) {
+                buffer_clear(&active_state->compression_buffer);
                 /* Skip padding. */
-                buffer_consume(&outgoing_packet, 8);
+                buffer_consume(&active_state->outgoing_packet, 8);
                 /* padding */
-                buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
-                buffer_compress(&outgoing_packet, &compression_buffer);
-                buffer_clear(&outgoing_packet);
-                buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
-                    buffer_len(&compression_buffer));
+                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));
         }
         /* Compute packet length without padding (add checksum, remove padding). */
-        len = buffer_len(&outgoing_packet) + 4 - 8;
+        len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
 
         /* Insert padding. Initialized to zero in packet_start1() */
         padding = 8 - len % 8;
-        if (!send_context.plaintext) {
-                cp = buffer_ptr(&outgoing_packet);
+        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();
@@ -630,33 +686,36 @@ packet_send1(void)
                         rnd >>= 8;
                 }
         }
-        buffer_consume(&outgoing_packet, 8 - padding);
+        buffer_consume(&active_state->outgoing_packet, 8 - padding);
 
         /* Add check bytes. */
-        checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
-            buffer_len(&outgoing_packet));
+        checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
+            buffer_len(&active_state->outgoing_packet));
         put_u32(buf, checksum);
-        buffer_append(&outgoing_packet, buf, 4);
+        buffer_append(&active_state->outgoing_packet, buf, 4);
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "packet_send plain: ");
-        buffer_dump(&outgoing_packet);
+        buffer_dump(&active_state->outgoing_packet);
 #endif
 
         /* Append to output. */
         put_u32(buf, len);
-        buffer_append(&output, buf, 4);
-        cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
-        cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
-            buffer_len(&outgoing_packet));
+        buffer_append(&active_state->output, buf, 4);
+        cp = buffer_append_space(&active_state->output,
+            buffer_len(&active_state->outgoing_packet));
+        cipher_crypt(&active_state->send_context, cp,
+            buffer_ptr(&active_state->outgoing_packet),
+            buffer_len(&active_state->outgoing_packet));
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "encrypted: ");
-        buffer_dump(&output);
+        buffer_dump(&active_state->output);
 #endif
-        p_send.packets++;
-        p_send.bytes += len + buffer_len(&outgoing_packet);
-        buffer_clear(&outgoing_packet);
+        active_state->p_send.packets++;
+        active_state->p_send.bytes += len +
+            buffer_len(&active_state->outgoing_packet);
+        buffer_clear(&active_state->outgoing_packet);
 
         /*
          * Note that the packet is now only buffered in output.  It won't be
@@ -678,22 +737,22 @@ set_newkeys(int mode)
         debug2("set_newkeys: mode %d", mode);
 
         if (mode == MODE_OUT) {
-                cc = &send_context;
+                cc = &active_state->send_context;
                 crypt_type = CIPHER_ENCRYPT;
-                p_send.packets = p_send.blocks = 0;
-                max_blocks = &max_blocks_out;
+                active_state->p_send.packets = active_state->p_send.blocks = 0;
+                max_blocks = &active_state->max_blocks_out;
         } else {
-                cc = &receive_context;
+                cc = &active_state->receive_context;
                 crypt_type = CIPHER_DECRYPT;
-                p_read.packets = p_read.blocks = 0;
-                max_blocks = &max_blocks_in;
+                active_state->p_read.packets = active_state->p_read.blocks = 0;
+                max_blocks = &active_state->max_blocks_in;
         }
-        if (newkeys[mode] != NULL) {
+        if (active_state->newkeys[mode] != NULL) {
                 debug("set_newkeys: rekeying");
                 cipher_cleanup(cc);
-                enc  = &newkeys[mode]->enc;
-                mac  = &newkeys[mode]->mac;
-                comp = &newkeys[mode]->comp;
+                enc  = &active_state->newkeys[mode]->enc;
+                mac  = &active_state->newkeys[mode]->mac;
+                comp = &active_state->newkeys[mode]->comp;
                 mac_clear(mac);
                 xfree(enc->name);
                 xfree(enc->iv);
@@ -701,14 +760,14 @@ set_newkeys(int mode)
                 xfree(mac->name);
                 xfree(mac->key);
                 xfree(comp->name);
-                xfree(newkeys[mode]);
+                xfree(active_state->newkeys[mode]);
         }
-        newkeys[mode] = kex_get_newkeys(mode);
-        if (newkeys[mode] == NULL)
+        active_state->newkeys[mode] = kex_get_newkeys(mode);
+        if (active_state->newkeys[mode] == NULL)
                 fatal("newkeys: no keys for mode %d", mode);
-        enc  = &newkeys[mode]->enc;
-        mac  = &newkeys[mode]->mac;
-        comp = &newkeys[mode]->comp;
+        enc  = &active_state->newkeys[mode]->enc;
+        mac  = &active_state->newkeys[mode]->mac;
+        comp = &active_state->newkeys[mode]->comp;
         if (mac_init(mac) == 0)
                 mac->enabled = 1;
         DBG(debug("cipher_init_context: %d", mode));
@@ -719,8 +778,8 @@ set_newkeys(int mode)
            memset(enc->key, 0, enc->key_len);
            memset(mac->key, 0, mac->key_len); */
         if ((comp->type == COMP_ZLIB ||
-            (comp->type == COMP_DELAYED && after_authentication)) &&
-            comp->enabled == 0) {
+            (comp->type == COMP_DELAYED &&
+             active_state->after_authentication)) && comp->enabled == 0) {
                 packet_init_compression();
                 if (mode == MODE_OUT)
                         buffer_compress_init_send(6);
@@ -736,8 +795,9 @@ 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 (rekey_limit)
-                *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
+        if (active_state->rekey_limit)
+                *max_blocks = MIN(*max_blocks,
+                    active_state->rekey_limit / enc->block_size);
 }
 
 /*
@@ -755,12 +815,12 @@ packet_enable_delayed_compress(void)
          * Remember that we are past the authentication step, so rekeying
          * with COMP_DELAYED will turn on compression immediately.
          */
-        after_authentication = 1;
+        active_state->after_authentication = 1;
         for (mode = 0; mode < MODE_MAX; mode++) {
                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
-                if (newkeys[mode] == NULL)
+                if (active_state->newkeys[mode] == NULL)
                         continue;
-                comp = &newkeys[mode]->comp;
+                comp = &active_state->newkeys[mode]->comp;
                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
                         packet_init_compression();
                         if (mode == MODE_OUT)
@@ -788,37 +848,39 @@ packet_send2_wrapped(void)
         Comp *comp = NULL;
         int block_size;
 
-        if (newkeys[MODE_OUT] != NULL) {
-                enc  = &newkeys[MODE_OUT]->enc;
-                mac  = &newkeys[MODE_OUT]->mac;
-                comp = &newkeys[MODE_OUT]->comp;
+        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;
         }
         block_size = enc ? enc->block_size : 8;
 
-        cp = buffer_ptr(&outgoing_packet);
+        cp = buffer_ptr(&active_state->outgoing_packet);
         type = cp[5];
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "plain:     ");
-        buffer_dump(&outgoing_packet);
+        buffer_dump(&active_state->outgoing_packet);
 #endif
 
         if (comp && comp->enabled) {
-                len = buffer_len(&outgoing_packet);
+                len = buffer_len(&active_state->outgoing_packet);
                 /* skip header, compress only payload */
-                buffer_consume(&outgoing_packet, 5);
-                buffer_clear(&compression_buffer);
-                buffer_compress(&outgoing_packet, &compression_buffer);
-                buffer_clear(&outgoing_packet);
-                buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
-                buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
-                    buffer_len(&compression_buffer));
+                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(&outgoing_packet)));
+                    buffer_len(&active_state->outgoing_packet)));
         }
 
         /* sizeof (packet_len + pad_len + payload) */
-        len = buffer_len(&outgoing_packet);
+        len = buffer_len(&active_state->outgoing_packet);
 
         /*
          * calc size of padding, alloc space, get random data,
@@ -827,17 +889,19 @@ packet_send2_wrapped(void)
         padlen = block_size - (len % block_size);
         if (padlen < 4)
                 padlen += block_size;
-        if (extra_pad) {
+        if (active_state->extra_pad) {
                 /* will wrap if extra_pad+padlen > 255 */
-                extra_pad  = roundup(extra_pad, block_size);
-                pad = extra_pad - ((len + padlen) % extra_pad);
+                active_state->extra_pad =
+                    roundup(active_state->extra_pad, block_size);
+                pad = active_state->extra_pad -
+                    ((len + padlen) % active_state->extra_pad);
                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
-                    pad, len, padlen, extra_pad);
+                    pad, len, padlen, active_state->extra_pad);
                 padlen += pad;
-                extra_pad = 0;
+                active_state->extra_pad = 0;
         }
-        cp = buffer_append_space(&outgoing_packet, padlen);
-        if (enc && !send_context.plaintext) {
+        cp = buffer_append_space(&active_state->outgoing_packet, padlen);
+        if (enc && !active_state->send_context.plaintext) {
                 /* random padding */
                 for (i = 0; i < padlen; i++) {
                         if (i % 4 == 0)
@@ -850,86 +914,88 @@ packet_send2_wrapped(void)
                 memset(cp, 0, padlen);
         }
         /* packet_length includes payload, padding and padding length field */
-        packet_length = buffer_len(&outgoing_packet) - 4;
-        cp = buffer_ptr(&outgoing_packet);
+        packet_length = buffer_len(&active_state->outgoing_packet) - 4;
+        cp = buffer_ptr(&active_state->outgoing_packet);
         put_u32(cp, packet_length);
         cp[4] = padlen;
         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 
         /* compute MAC over seqnr and packet(length fields, payload, padding) */
         if (mac && mac->enabled) {
-                macbuf = mac_compute(mac, p_send.seqnr,
-                    buffer_ptr(&outgoing_packet),
-                    buffer_len(&outgoing_packet));
-                DBG(debug("done calc MAC out #%d", p_send.seqnr));
+                macbuf = mac_compute(mac, active_state->p_send.seqnr,
+                    buffer_ptr(&active_state->outgoing_packet),
+                    buffer_len(&active_state->outgoing_packet));
+                DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
         }
         /* encrypt packet and append to output buffer. */
-        cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
-        cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
-            buffer_len(&outgoing_packet));
+        cp = buffer_append_space(&active_state->output,
+            buffer_len(&active_state->outgoing_packet));
+        cipher_crypt(&active_state->send_context, cp,
+            buffer_ptr(&active_state->outgoing_packet),
+            buffer_len(&active_state->outgoing_packet));
         /* append unencrypted MAC */
         if (mac && mac->enabled)
-                buffer_append(&output, macbuf, mac->mac_len);
+                buffer_append(&active_state->output, macbuf, mac->mac_len);
 #ifdef PACKET_DEBUG
         fprintf(stderr, "encrypted: ");
-        buffer_dump(&output);
+        buffer_dump(&active_state->output);
 #endif
         /* increment sequence number for outgoing packets */
-        if (++p_send.seqnr == 0)
+        if (++active_state->p_send.seqnr == 0)
                 logit("outgoing seqnr wraps around");
-        if (++p_send.packets == 0)
+        if (++active_state->p_send.packets == 0)
                 if (!(datafellows & SSH_BUG_NOREKEY))
                         fatal("XXX too many packets with same key");
-        p_send.blocks += (packet_length + 4) / block_size;
-        p_send.bytes += packet_length + 4;
-        buffer_clear(&outgoing_packet);
+        active_state->p_send.blocks += (packet_length + 4) / block_size;
+        active_state->p_send.bytes += packet_length + 4;
+        buffer_clear(&active_state->outgoing_packet);
 
         if (type == SSH2_MSG_NEWKEYS)
                 set_newkeys(MODE_OUT);
-        else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
+        else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
                 packet_enable_delayed_compress();
 }
 
 static void
 packet_send2(void)
 {
-        static int rekeying = 0;
         struct packet *p;
         u_char type, *cp;
 
-        cp = buffer_ptr(&outgoing_packet);
+        cp = buffer_ptr(&active_state->outgoing_packet);
         type = cp[5];
 
         /* during rekeying we can only send key exchange messages */
-        if (rekeying) {
+        if (active_state->rekeying) {
                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
                         debug("enqueue packet: %u", type);
                         p = xmalloc(sizeof(*p));
                         p->type = type;
-                        memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
-                        buffer_init(&outgoing_packet);
-                        TAILQ_INSERT_TAIL(&outgoing, p, next);
+                        memcpy(&p->payload, &active_state->outgoing_packet,
+                            sizeof(Buffer));
+                        buffer_init(&active_state->outgoing_packet);
+                        TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
                         return;
                 }
         }
 
         /* rekeying starts with sending KEXINIT */
         if (type == SSH2_MSG_KEXINIT)
-                rekeying = 1;
+                active_state->rekeying = 1;
 
         packet_send2_wrapped();
 
         /* after a NEWKEYS message we can send the complete queue */
         if (type == SSH2_MSG_NEWKEYS) {
-                rekeying = 0;
-                while ((p = TAILQ_FIRST(&outgoing))) {
+                active_state->rekeying = 0;
+                while ((p = TAILQ_FIRST(&active_state->outgoing))) {
                         type = p->type;
                         debug("dequeue packet: %u", type);
-                        buffer_free(&outgoing_packet);
-                        memcpy(&outgoing_packet, &p->payload,
+                        buffer_free(&active_state->outgoing_packet);
+                        memcpy(&active_state->outgoing_packet, &p->payload,
                             sizeof(Buffer));
-                        TAILQ_REMOVE(&outgoing, p, next);
+                        TAILQ_REMOVE(&active_state->outgoing, p, next);
                         xfree(p);
                         packet_send2_wrapped();
                 }
@@ -955,15 +1021,15 @@ packet_send(void)
 int
 packet_read_seqnr(u_int32_t *seqnr_p)
 {
-        int type, len, ret, ms_remain;
+        int type, len, ret, ms_remain, cont;
         fd_set *setp;
         char buf[8192];
         struct timeval timeout, start, *timeoutp = NULL;
 
         DBG(debug("packet_read()"));
 
-        setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
-            sizeof(fd_mask));
+        setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
+            NFDBITS), sizeof(fd_mask));
 
         /* Since we are blocking, ensure that all written packets have been sent. */
         packet_write_wait();
@@ -987,27 +1053,27 @@ packet_read_seqnr(u_int32_t *seqnr_p)
                  * Otherwise, wait for some data to arrive, add it to the
                  * buffer, and try again.
                  */
-                memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
-                    sizeof(fd_mask));
-                FD_SET(connection_in, setp);
+                memset(setp, 0, howmany(active_state->connection_in + 1,
+                    NFDBITS) * sizeof(fd_mask));
+                FD_SET(active_state->connection_in, setp);
 
-                if (packet_timeout_ms > 0) {
-                        ms_remain = packet_timeout_ms;
+                if (active_state->packet_timeout_ms > 0) {
+                        ms_remain = active_state->packet_timeout_ms;
                         timeoutp = &timeout;
                 }
                 /* Wait for some data to arrive. */
                 for (;;) {
-                        if (packet_timeout_ms != -1) {
+                        if (active_state->packet_timeout_ms != -1) {
                                 ms_to_timeval(&timeout, ms_remain);
                                 gettimeofday(&start, NULL);
                         }
-                        if ((ret = select(connection_in + 1, setp, NULL,
-                            NULL, timeoutp)) >= 0)
+                        if ((ret = select(active_state->connection_in + 1, setp,
+                            NULL, NULL, timeoutp)) >= 0)
                                 break;
-                        if (errno != EAGAIN && errno != EINTR &&
+                        if (errno != EAGAIN && errno != EINTR &&
                             errno != EWOULDBLOCK)
                                 break;
-                        if (packet_timeout_ms == -1)
+                        if (active_state->packet_timeout_ms == -1)
                                 continue;
                         ms_subtract_diff(&start, &ms_remain);
                         if (ms_remain <= 0) {
@@ -1021,7 +1087,11 @@ packet_read_seqnr(u_int32_t *seqnr_p)
                         cleanup_exit(255);
                 }
                 /* Read data from the socket. */
-                len = read(connection_in, buf, sizeof(buf));
+                do {
+                        cont = 0;
+                        len = roaming_read(active_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);
@@ -1073,31 +1143,32 @@ packet_read_poll1(void)
         u_int checksum, stored_checksum;
 
         /* Check if input size is less than minimum packet size. */
-        if (buffer_len(&input) < 4 + 8)
+        if (buffer_len(&active_state->input) < 4 + 8)
                 return SSH_MSG_NONE;
         /* Get length of incoming packet. */
-        cp = buffer_ptr(&input);
+        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);
         padded_len = (len + 8) & ~7;
 
         /* Check if the packet has been entirely received. */
-        if (buffer_len(&input) < 4 + padded_len)
+        if (buffer_len(&active_state->input) < 4 + padded_len)
                 return SSH_MSG_NONE;
 
         /* The entire packet is in buffer. */
 
         /* Consume packet length. */
-        buffer_consume(&input, 4);
+        buffer_consume(&active_state->input, 4);
 
         /*
          * Cryptographic attack detector for ssh
          * (C)1998 CORE-SDI, Buenos Aires Argentina
          * Ariel Futoransky(futo@core-sdi.com)
          */
-        if (!receive_context.plaintext) {
-                switch (detect_attack(buffer_ptr(&input), padded_len)) {
+        if (!active_state->receive_context.plaintext) {
+                switch (detect_attack(buffer_ptr(&active_state->input),
+                    padded_len)) {
                 case DEATTACK_DETECTED:
                         packet_disconnect("crc32 compensation attack: "
                             "network attack detected");
@@ -1108,45 +1179,48 @@ packet_read_poll1(void)
         }
 
         /* Decrypt data to incoming_packet. */
-        buffer_clear(&incoming_packet);
-        cp = buffer_append_space(&incoming_packet, padded_len);
-        cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
+        buffer_clear(&active_state->incoming_packet);
+        cp = buffer_append_space(&active_state->incoming_packet, padded_len);
+        cipher_crypt(&active_state->receive_context, cp,
+            buffer_ptr(&active_state->input), padded_len);
 
-        buffer_consume(&input, padded_len);
+        buffer_consume(&active_state->input, padded_len);
 
 #ifdef PACKET_DEBUG
         fprintf(stderr, "read_poll plain: ");
-        buffer_dump(&incoming_packet);
+        buffer_dump(&active_state->incoming_packet);
 #endif
 
         /* Compute packet checksum. */
-        checksum = ssh_crc32(buffer_ptr(&incoming_packet),
-            buffer_len(&incoming_packet) - 4);
+        checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
+            buffer_len(&active_state->incoming_packet) - 4);
 
         /* Skip padding. */
-        buffer_consume(&incoming_packet, 8 - len % 8);
+        buffer_consume(&active_state->incoming_packet, 8 - len % 8);
 
         /* Test check bytes. */
-        if (len != buffer_len(&incoming_packet))
+        if (len != buffer_len(&active_state->incoming_packet))
                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
-                    len, buffer_len(&incoming_packet));
+                    len, buffer_len(&active_state->incoming_packet));
 
-        cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
+        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(&incoming_packet, 4);
-
-        if (packet_compression) {
-                buffer_clear(&compression_buffer);
-                buffer_uncompress(&incoming_packet, &compression_buffer);
-                buffer_clear(&incoming_packet);
-                buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
-                    buffer_len(&compression_buffer));
+        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));
         }
-        p_read.packets++;
-        p_read.bytes += padded_len + 4;
-        type = buffer_get_char(&incoming_packet);
+        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;
@@ -1155,7 +1229,6 @@ packet_read_poll1(void)
 static int
 packet_read_poll2(u_int32_t *seqnr_p)
 {
-        static u_int packet_length = 0;
         u_int padlen, need;
         u_char *macbuf, *cp, type;
         u_int maclen, block_size;
@@ -1163,50 +1236,52 @@ packet_read_poll2(u_int32_t *seqnr_p)
         Mac *mac   = NULL;
         Comp *comp = NULL;
 
-        if (packet_discard)
+        if (active_state->packet_discard)
                 return SSH_MSG_NONE;
 
-        if (newkeys[MODE_IN] != NULL) {
-                enc  = &newkeys[MODE_IN]->enc;
-                mac  = &newkeys[MODE_IN]->mac;
-                comp = &newkeys[MODE_IN]->comp;
+        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;
         }
         maclen = mac && mac->enabled ? mac->mac_len : 0;
         block_size = enc ? enc->block_size : 8;
 
-        if (packet_length == 0) {
+        if (active_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(&input) < block_size)
+                if (buffer_len(&active_state->input) < block_size)
                         return SSH_MSG_NONE;
-                buffer_clear(&incoming_packet);
-                cp = buffer_append_space(&incoming_packet, block_size);
-                cipher_crypt(&receive_context, cp, buffer_ptr(&input),
+                buffer_clear(&active_state->incoming_packet);
+                cp = buffer_append_space(&active_state->incoming_packet,
                     block_size);
-                cp = buffer_ptr(&incoming_packet);
-                packet_length = get_u32(cp);
-                if (packet_length < 1 + 4 || packet_length > PACKET_MAX_SIZE) {
+                cipher_crypt(&active_state->receive_context, cp,
+                    buffer_ptr(&active_state->input), block_size);
+                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) {
 #ifdef PACKET_DEBUG
-                        buffer_dump(&incoming_packet);
+                        buffer_dump(&active_state->incoming_packet);
 #endif
-                        logit("Bad packet length %u.", packet_length);
-                        packet_start_discard(enc, mac, packet_length,
+                        logit("Bad packet length %u.", active_state->packlen);
+                        packet_start_discard(enc, mac, active_state->packlen,
                             PACKET_MAX_SIZE);
                         return SSH_MSG_NONE;
                 }
-                DBG(debug("input: packet len %u", packet_length+4));
-                buffer_consume(&input, block_size);
+                DBG(debug("input: packet len %u", active_state->packlen+4));
+                buffer_consume(&active_state->input, block_size);
         }
         /* we have a partial packet of block_size bytes */
-        need = 4 + packet_length - block_size;
+        need = 4 + active_state->packlen - block_size;
         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
             need, maclen));
         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, packet_length,
+                packet_start_discard(enc, mac, active_state->packlen,
                     PACKET_MAX_SIZE - block_size);
                 return SSH_MSG_NONE;
         }
@@ -1214,84 +1289,90 @@ packet_read_poll2(u_int32_t *seqnr_p)
          * check if the entire packet has been received and
          * decrypt into incoming_packet
          */
-        if (buffer_len(&input) < need + maclen)
+        if (buffer_len(&active_state->input) < need + maclen)
                 return SSH_MSG_NONE;
 #ifdef PACKET_DEBUG
         fprintf(stderr, "read_poll enc/full: ");
-        buffer_dump(&input);
+        buffer_dump(&active_state->input);
 #endif
-        cp = buffer_append_space(&incoming_packet, need);
-        cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
-        buffer_consume(&input, need);
+        cp = buffer_append_space(&active_state->incoming_packet, need);
+        cipher_crypt(&active_state->receive_context, cp,
+            buffer_ptr(&active_state->input), need);
+        buffer_consume(&active_state->input, need);
         /*
          * compute MAC over seqnr and packet,
          * increment sequence number for incoming packet
          */
         if (mac && mac->enabled) {
-                macbuf = mac_compute(mac, p_read.seqnr,
-                    buffer_ptr(&incoming_packet),
-                    buffer_len(&incoming_packet));
-                if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) {
+                macbuf = mac_compute(mac, active_state->p_read.seqnr,
+                    buffer_ptr(&active_state->incoming_packet),
+                    buffer_len(&active_state->incoming_packet));
+                if (memcmp(macbuf, buffer_ptr(&active_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, packet_length,
+                        packet_start_discard(enc, mac, active_state->packlen,
                             PACKET_MAX_SIZE - need);
                         return SSH_MSG_NONE;
                 }
                                 
-                DBG(debug("MAC #%d ok", p_read.seqnr));
-                buffer_consume(&input, mac->mac_len);
+                DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
+                buffer_consume(&active_state->input, mac->mac_len);
         }
         /* XXX now it's safe to use fatal/packet_disconnect */
         if (seqnr_p != NULL)
-                *seqnr_p = p_read.seqnr;
-        if (++p_read.seqnr == 0)
+                *seqnr_p = active_state->p_read.seqnr;
+        if (++active_state->p_read.seqnr == 0)
                 logit("incoming seqnr wraps around");
-        if (++p_read.packets == 0)
+        if (++active_state->p_read.packets == 0)
                 if (!(datafellows & SSH_BUG_NOREKEY))
                         fatal("XXX too many packets with same key");
-        p_read.blocks += (packet_length + 4) / block_size;
-        p_read.bytes += packet_length + 4;
+        active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
+        active_state->p_read.bytes += active_state->packlen + 4;
 
         /* get padlen */
-        cp = buffer_ptr(&incoming_packet);
+        cp = buffer_ptr(&active_state->incoming_packet);
         padlen = cp[4];
         DBG(debug("input: padlen %d", padlen));
         if (padlen < 4)
                 packet_disconnect("Corrupted padlen %d on input.", padlen);
 
         /* skip packet size + padlen, discard padding */
-        buffer_consume(&incoming_packet, 4 + 1);
-        buffer_consume_end(&incoming_packet, padlen);
+        buffer_consume(&active_state->incoming_packet, 4 + 1);
+        buffer_consume_end(&active_state->incoming_packet, padlen);
 
-        DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
+        DBG(debug("input: len before de-compress %d",
+            buffer_len(&active_state->incoming_packet)));
         if (comp && comp->enabled) {
-                buffer_clear(&compression_buffer);
-                buffer_uncompress(&incoming_packet, &compression_buffer);
-                buffer_clear(&incoming_packet);
-                buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
-                    buffer_len(&compression_buffer));
+                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(&incoming_packet)));
+                    buffer_len(&active_state->incoming_packet)));
         }
         /*
          * get packet type, implies consume.
          * return length of payload (without type field)
          */
-        type = buffer_get_char(&incoming_packet);
+        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 && !server_side)
+        else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
+            !active_state->server_side)
                 packet_enable_delayed_compress();
 #ifdef PACKET_DEBUG
         fprintf(stderr, "read/plain[%d]:\r\n", type);
-        buffer_dump(&incoming_packet);
+        buffer_dump(&active_state->incoming_packet);
 #endif
         /* reset for next packet */
-        packet_length = 0;
+        active_state->packlen = 0;
         return type;
 }
 
@@ -1306,7 +1387,7 @@ packet_read_poll_seqnr(u_int32_t *seqnr_p)
                 if (compat20) {
                         type = packet_read_poll2(seqnr_p);
                         if (type) {
-                                keep_alive_timeouts = 0;
+                                active_state->keep_alive_timeouts = 0;
                                 DBG(debug("received packet type %d", type));
                         }
                         switch (type) {
@@ -1376,14 +1457,14 @@ packet_read_poll(void)
 void
 packet_process_incoming(const char *buf, u_int len)
 {
-        if (packet_discard) {
-                keep_alive_timeouts = 0; /* ?? */
-                if (len >= packet_discard)
+        if (active_state->packet_discard) {
+                active_state->keep_alive_timeouts = 0; /* ?? */
+                if (len >= active_state->packet_discard)
                         packet_stop_discard();
-                packet_discard -= len;
+                active_state->packet_discard -= len;
                 return;
         }
-        buffer_append(&input, buf, len);
+        buffer_append(&active_state->input, buf, len);
 }
 
 /* Returns a character from the packet. */
@@ -1393,7 +1474,7 @@ packet_get_char(void)
 {
         char ch;
 
-        buffer_get(&incoming_packet, &ch, 1);
+        buffer_get(&active_state->incoming_packet, &ch, 1);
         return (u_char) ch;
 }
 
@@ -1402,7 +1483,15 @@ packet_get_char(void)
 u_int
 packet_get_int(void)
 {
-        return buffer_get_int(&incoming_packet);
+        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);
 }
 
 /*
@@ -1413,29 +1502,29 @@ packet_get_int(void)
 void
 packet_get_bignum(BIGNUM * value)
 {
-        buffer_get_bignum(&incoming_packet, value);
+        buffer_get_bignum(&active_state->incoming_packet, value);
 }
 
 void
 packet_get_bignum2(BIGNUM * value)
 {
-        buffer_get_bignum2(&incoming_packet, value);
+        buffer_get_bignum2(&active_state->incoming_packet, value);
 }
 
 void *
 packet_get_raw(u_int *length_ptr)
 {
-        u_int bytes = buffer_len(&incoming_packet);
+        u_int bytes = buffer_len(&active_state->incoming_packet);
 
         if (length_ptr != NULL)
                 *length_ptr = bytes;
-        return buffer_ptr(&incoming_packet);
+        return buffer_ptr(&active_state->incoming_packet);
 }
 
 int
 packet_remaining(void)
 {
-        return buffer_len(&incoming_packet);
+        return buffer_len(&active_state->incoming_packet);
 }
 
 /*
@@ -1448,13 +1537,13 @@ packet_remaining(void)
 void *
 packet_get_string(u_int *length_ptr)
 {
-        return buffer_get_string(&incoming_packet, length_ptr);
+        return buffer_get_string(&active_state->incoming_packet, length_ptr);
 }
 
 void *
 packet_get_string_ptr(u_int *length_ptr)
 {
-        return buffer_get_string_ptr(&incoming_packet, length_ptr);
+        return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
 }
 
 /*
@@ -1547,23 +1636,25 @@ packet_disconnect(const char *fmt,...)
 void
 packet_write_poll(void)
 {
-        int len = buffer_len(&output);
+        int len = buffer_len(&active_state->output);
+        int cont;
 
         if (len > 0) {
-                len = write(connection_out, buffer_ptr(&output), len);
+                cont = 0;
+                len = roaming_write(active_state->connection_out,
+                    buffer_ptr(&active_state->output), len, &cont);
                 if (len == -1) {
                         if (errno == EINTR || errno == EAGAIN ||
                             errno == EWOULDBLOCK)
                                 return;
                         fatal("Write failed: %.100s", strerror(errno));
                 }
-                if (len == 0)
+                if (len == 0 && !cont)
                         fatal("Write connection closed");
-                buffer_consume(&output, len);
+                buffer_consume(&active_state->output, len);
         }
 }
 
-
 /*
  * Calls packet_write_poll repeatedly until all pending output data has been
  * written.
@@ -1576,30 +1667,30 @@ packet_write_wait(void)
         int ret, ms_remain;
         struct timeval start, timeout, *timeoutp = NULL;
 
-        setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
-            sizeof(fd_mask));
+        setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
+            NFDBITS), sizeof(fd_mask));
         packet_write_poll();
         while (packet_have_data_to_write()) {
-                memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
-                    sizeof(fd_mask));
-                FD_SET(connection_out, setp);
+                memset(setp, 0, howmany(active_state->connection_out + 1,
+                    NFDBITS) * sizeof(fd_mask));
+                FD_SET(active_state->connection_out, setp);
 
-                if (packet_timeout_ms > 0) {
-                        ms_remain = packet_timeout_ms;
+                if (active_state->packet_timeout_ms > 0) {
+                        ms_remain = active_state->packet_timeout_ms;
                         timeoutp = &timeout;
                 }
                 for (;;) {
-                        if (packet_timeout_ms != -1) {
+                        if (active_state->packet_timeout_ms != -1) {
                                 ms_to_timeval(&timeout, ms_remain);
                                 gettimeofday(&start, NULL);
                         }
-                        if ((ret = select(connection_out + 1, NULL, setp,
-                            NULL, timeoutp)) >= 0)
+                        if ((ret = select(active_state->connection_out + 1,
+                            NULL, setp, NULL, timeoutp)) >= 0)
                                 break;
-                        if (errno != EAGAIN && errno != EINTR &&
+                        if (errno != EAGAIN && errno != EINTR &&
                             errno != EWOULDBLOCK)
                                 break;
-                        if (packet_timeout_ms == -1)
+                        if (active_state->packet_timeout_ms == -1)
                                 continue;
                         ms_subtract_diff(&start, &ms_remain);
                         if (ms_remain <= 0) {
@@ -1622,7 +1713,7 @@ packet_write_wait(void)
 int
 packet_have_data_to_write(void)
 {
-        return buffer_len(&output) != 0;
+        return buffer_len(&active_state->output) != 0;
 }
 
 /* Returns true if there is not too much data to write to the connection. */
@@ -1630,13 +1721,12 @@ packet_have_data_to_write(void)
 int
 packet_not_very_much_data_to_write(void)
 {
-        if (interactive_mode)
-                return buffer_len(&output) < 16384;
+        if (active_state->interactive_mode)
+                return buffer_len(&active_state->output) < 16384;
         else
-                return buffer_len(&output) < 128 * 1024;
+                return buffer_len(&active_state->output) < 128 * 1024;
 }
 
-
 static void
 packet_set_tos(int interactive)
 {
@@ -1646,7 +1736,7 @@ packet_set_tos(int interactive)
         if (!packet_connection_is_on_socket() ||
             !packet_connection_is_ipv4())
                 return;
-        if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
+        if (setsockopt(active_state->connection_in, IPPROTO_IP, IP_TOS, &tos,
             sizeof(tos)) < 0)
                 error("setsockopt IP_TOS %d: %.100s:",
                     tos, strerror(errno));
@@ -1658,19 +1748,17 @@ packet_set_tos(int interactive)
 void
 packet_set_interactive(int interactive)
 {
-        static int called = 0;
-
-        if (called)
+        if (active_state->set_interactive_called)
                 return;
-        called = 1;
+        active_state->set_interactive_called = 1;
 
         /* Record that we are in interactive mode. */
-        interactive_mode = interactive;
+        active_state->interactive_mode = interactive;
 
         /* Only set socket options if using a socket.  */
         if (!packet_connection_is_on_socket())
                 return;
-        set_nodelay(connection_in);
+        set_nodelay(active_state->connection_in);
         packet_set_tos(interactive);
 }
 
@@ -1679,34 +1767,50 @@ packet_set_interactive(int interactive)
 int
 packet_is_interactive(void)
 {
-        return interactive_mode;
+        return active_state->interactive_mode;
 }
 
 int
 packet_set_maxsize(u_int s)
 {
-        static int called = 0;
-
-        if (called) {
+        if (active_state->set_maxsize_called) {
                 logit("packet_set_maxsize: called twice: old %d new %d",
-                    max_packet_size, s);
+                    active_state->max_packet_size, s);
                 return -1;
         }
         if (s < 4 * 1024 || s > 1024 * 1024) {
                 logit("packet_set_maxsize: bad size %d", s);
                 return -1;
         }
-        called = 1;
+        active_state->set_maxsize_called = 1;
         debug("packet_set_maxsize: setting to %d", s);
-        max_packet_size = s;
+        active_state->max_packet_size = s;
         return s;
 }
 
+int
+packet_inc_alive_timeouts(void)
+{
+        return ++active_state->keep_alive_timeouts;
+}
+
+void
+packet_set_alive_timeouts(int ka)
+{
+        active_state->keep_alive_timeouts = ka;
+}
+
+u_int
+packet_get_maxsize(void)
+{
+        return active_state->max_packet_size;
+}
+
 /* roundup current message to pad bytes */
 void
 packet_add_padding(u_char pad)
 {
-        extra_pad = pad;
+        active_state->extra_pad = pad;
 }
 
 /*
@@ -1743,26 +1847,93 @@ packet_need_rekeying(void)
         if (datafellows & SSH_BUG_NOREKEY)
                 return 0;
         return
-            (p_send.packets > MAX_PACKETS) ||
-            (p_read.packets > MAX_PACKETS) ||
-            (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
-            (max_blocks_in  && (p_read.blocks > max_blocks_in));
+            (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));
 }
 
 void
 packet_set_rekey_limit(u_int32_t bytes)
 {
-        rekey_limit = bytes;
+        active_state->rekey_limit = bytes;
 }
 
 void
 packet_set_server(void)
 {
-        server_side = 1;
+        active_state->server_side = 1;
 }
 
 void
 packet_set_authenticated(void)
 {
-        after_authentication = 1;
+        active_state->after_authentication = 1;
+}
+
+void *
+packet_get_input(void)
+{
+        return (void *)&active_state->input;
+}
+
+void *
+packet_get_output(void)
+{
+        return (void *)&active_state->output;
+}
+
+void *
+packet_get_newkeys(int mode)
+{
+        return (void *)active_state->newkeys[mode];
+}
+
+/*
+ * Save the state for the real connection, and use a separate state when
+ * resuming a suspended connection.
+ */
+void
+packet_backup_state(void)
+{
+        struct session_state *tmp;
+
+        close(active_state->connection_in);
+        active_state->connection_in = -1;
+        close(active_state->connection_out);
+        active_state->connection_out = -1;
+        if (backup_state)
+                tmp = backup_state;
+        else
+                tmp = alloc_session_state();
+        backup_state = active_state;
+        active_state = tmp;
+}
+
+/*
+ * Swap in the old state when resuming a connecion.
+ */
+void
+packet_restore_state(void)
+{
+        struct session_state *tmp;
+        void *buf;
+        u_int len;
+
+        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);
+        if (len > 0) {
+                buf = buffer_ptr(&backup_state->input);
+                buffer_append(&active_state->input, buf, len);
+                buffer_clear(&backup_state->input);
+                add_recv_bytes(len);
+        }
 }