1 files changed, 45 insertions, 21 deletions

diff --git a/kex.c b/kex.c
index bdbf3882c..2c1cacfec 100644
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.51 2002/06/24 14:55:38 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.54 2003/02/16 17:09:57 markus Exp $");
 
 #include <openssl/crypto.h>
 
@@ -44,11 +44,6 @@ RCSID("$OpenBSD: kex.c,v 1.51 2002/06/24 14:55:38 markus Exp $");
 
 #define KEX_COOKIE_LEN  16
 
-/* Use privilege separation for sshd */
-int use_privsep;
-struct monitor *pmonitor;
-
-
 /* prototype */
 static void kex_kexinit_finish(Kex *);
 static void kex_choose_conf(Kex *);
@@ -74,7 +69,7 @@ kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
 
 /* parse buffer and return algorithm proposal */
 static char **
-kex_buf2prop(Buffer *raw)
+kex_buf2prop(Buffer *raw, int *first_kex_follows)
 {
         Buffer b;
         int i;
@@ -94,6 +89,8 @@ kex_buf2prop(Buffer *raw)
         }
         /* first kex follows / reserved */
         i = buffer_get_char(&b);
+        if (first_kex_follows != NULL)
+                *first_kex_follows = i;
         debug2("kex_parse_kexinit: first_kex_follows %d ", i);
         i = buffer_get_int(&b);
         debug2("kex_parse_kexinit: reserved %d ", i);
@@ -135,7 +132,7 @@ kex_finish(Kex *kex)
         /* packet_write_wait(); */
         debug("SSH2_MSG_NEWKEYS sent");
 
-        debug("waiting for SSH2_MSG_NEWKEYS");
+        debug("expecting SSH2_MSG_NEWKEYS");
         packet_read_expect(SSH2_MSG_NEWKEYS);
         packet_check_eom();
         debug("SSH2_MSG_NEWKEYS received");
@@ -235,14 +232,10 @@ kex_kexinit_finish(Kex *kex)
 
         kex_choose_conf(kex);
 
-        switch (kex->kex_type) {
-        case DH_GRP1_SHA1:
-                kexdh(kex);
-                break;
-        case DH_GEX_SHA1:
-                kexgex(kex);
-                break;
-        default:
+        if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
+            kex->kex[kex->kex_type] != NULL) {
+                (kex->kex[kex->kex_type])(kex);
+        } else {
                 fatal("Unsupported key exchange %d", kex->kex_type);
         }
 }
@@ -299,9 +292,9 @@ choose_kex(Kex *k, char *client, char *server)
         if (k->name == NULL)
                 fatal("no kex alg");
         if (strcmp(k->name, KEX_DH1) == 0) {
-                k->kex_type = DH_GRP1_SHA1;
+                k->kex_type = KEX_DH_GRP1_SHA1;
         } else if (strcmp(k->name, KEX_DHGEX) == 0) {
-                k->kex_type = DH_GEX_SHA1;
+                k->kex_type = KEX_DH_GEX_SHA1;
         } else
                 fatal("bad kex alg %s", k->name);
 }
@@ -317,6 +310,30 @@ choose_hostkeyalg(Kex *k, char *client, char *server)
         xfree(hostkeyalg);
 }
 
+static int 
+proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
+{
+        static int check[] = {
+                PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
+        };
+        int *idx;
+        char *p;
+
+        for (idx = &check[0]; *idx != -1; idx++) {
+                if ((p = strchr(my[*idx], ',')) != NULL)
+                        *p = '\0';
+                if ((p = strchr(peer[*idx], ',')) != NULL)
+                        *p = '\0';
+                if (strcmp(my[*idx], peer[*idx]) != 0) {
+                        debug2("proposal mismatch: my %s peer %s",
+                            my[*idx], peer[*idx]);
+                        return (0);
+                }
+        }
+        debug2("proposals match");
+        return (1);
+}
+
 static void
 kex_choose_conf(Kex *kex)
 {
@@ -327,9 +344,10 @@ kex_choose_conf(Kex *kex)
         int mode;
         int ctos;                               /* direction: if true client-to-server */
         int need;
+        int first_kex_follows, type;
 
-        my   = kex_buf2prop(&kex->my);
-        peer = kex_buf2prop(&kex->peer);
+        my   = kex_buf2prop(&kex->my, NULL);
+        peer = kex_buf2prop(&kex->peer, &first_kex_follows);
 
         if (kex->server) {
                 cprop=peer;
@@ -373,6 +391,12 @@ kex_choose_conf(Kex *kex)
         /* XXX need runden? */
         kex->we_need = need;
 
+        /* ignore the next message if the proposals do not match */
+        if (first_kex_follows && !proposals_match(my, peer)) {
+                type = packet_read();
+                debug2("skipping next packet (type %u)", type);
+        }
+
         kex_prop_free(my);
         kex_prop_free(peer);
 }
@@ -433,7 +457,7 @@ kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
         for (i = 0; i < NKEYS; i++)
                 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
 
-        debug("kex_derive_keys");
+        debug2("kex_derive_keys");
         for (mode = 0; mode < MODE_MAX; mode++) {
                 current_keys[mode] = kex->newkeys[mode];
                 kex->newkeys[mode] = NULL;