3 files changed, 38 insertions, 65 deletions

diff --git a/compat.c b/compat.c
index 0934de90f..cea63d268 100644
--- a/compat.c
+++ b/compat.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: compat.c,v 1.89 2015/04/10 05:16:50 dtucker Exp $ */
+/* $OpenBSD: compat.c,v 1.90 2015/04/13 02:04:08 djm Exp $ */
 /*
  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  *
@@ -165,6 +165,7 @@ compat_datafellows(const char *version)
                   "OSU_1.5alpha3*",     SSH_BUG_PASSWORDPAD },
                 { "*SSH_Version_Mapper*",
                                         SSH_BUG_SCANNER },
+                { "PuTTY*",             SSH_OLD_DHGEX },
                 { "Probe-*",
                                         SSH_BUG_PROBE },
                 { "TeraTerm SSH*,"
@@ -284,15 +285,20 @@ compat_pkalg_proposal(char *pkalg_prop)
 }
 
 char *
-compat_kex_proposal(char *kex_prop)
+compat_kex_proposal(char *p)
 {
-        if (!(datafellows & SSH_BUG_CURVE25519PAD))
-                return kex_prop;
-        debug2("%s: original KEX proposal: %s", __func__, kex_prop);
-        kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org");
-        debug2("%s: compat KEX proposal: %s", __func__, kex_prop);
-        if (*kex_prop == '\0')
+        if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
+                return p;
+        debug2("%s: original KEX proposal: %s", __func__, p);
+        if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
+                p = filter_proposal(p, "curve25519-sha256@libssh.org");
+        if ((datafellows & SSH_OLD_DHGEX) != 0) {
+                p = filter_proposal(p, "diffie-hellman-group-exchange-sha256");
+                p = filter_proposal(p, "diffie-hellman-group-exchange-sha1");
+        }
+        debug2("%s: compat KEX proposal: %s", __func__, p);
+        if (*p == '\0')
                 fatal("No supported key exchange algorithms found");
-        return kex_prop;
+        return p;
 }
 
diff --git a/kexgexc.c b/kexgexc.c
index e8e059a88..3f20491c4 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.20 2015/01/26 06:10:03 djm Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.21 2015/04/13 02:04:08 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -65,25 +65,15 @@ kexgex_client(struct ssh *ssh)
         kex->min = DH_GRP_MIN;
         kex->max = DH_GRP_MAX;
         kex->nbits = nbits;
-        if (ssh->compat & SSH_OLD_DHGEX) {
-                /* Old GEX request */
-                if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST_OLD))
-                    != 0 ||
-                    (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
-                    (r = sshpkt_send(ssh)) != 0)
-                        goto out;
-                debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", kex->nbits);
-        } else {
-                /* New GEX request */
-                if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
-                    (r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
-                    (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
-                    (r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
-                    (r = sshpkt_send(ssh)) != 0)
-                        goto out;
-                debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
-                    kex->min, kex->nbits, kex->max);
-        }
+        /* New GEX request */
+        if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
+            (r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
+            (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
+            (r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                goto out;
+        debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
+            kex->min, kex->nbits, kex->max);
 #ifdef DEBUG_KEXDH
         fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
             kex->min, kex->nbits, kex->max);
diff --git a/kexgexs.c b/kexgexs.c
index 9c281d288..ff6c6879e 100644
--- a/kexgexs.c
+++ b/kexgexs.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexs.c,v 1.24 2015/01/26 06:10:03 djm Exp $ */
+/* $OpenBSD: kexgexs.c,v 1.25 2015/04/13 02:04:08 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -60,8 +60,6 @@ static int input_kex_dh_gex_init(int, u_int32_t, void *);
 int
 kexgex_server(struct ssh *ssh)
 {
-        ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST_OLD,
-            &input_kex_dh_gex_request);
         ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST,
             &input_kex_dh_gex_request);
         debug("expecting SSH2_MSG_KEX_DH_GEX_REQUEST");
@@ -76,36 +74,19 @@ input_kex_dh_gex_request(int type, u_int32_t seq, void *ctxt)
         int r;
         u_int min = 0, max = 0, nbits = 0;
 
-        switch (type) {
-        case SSH2_MSG_KEX_DH_GEX_REQUEST:
-                debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
-                if ((r = sshpkt_get_u32(ssh, &min)) != 0 ||
-                    (r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
-                    (r = sshpkt_get_u32(ssh, &max)) != 0 ||
-                    (r = sshpkt_get_end(ssh)) != 0)
-                        goto out;
-                kex->nbits = nbits;
-                kex->min = min;
-                kex->max = max;
-                min = MAX(DH_GRP_MIN, min);
-                max = MIN(DH_GRP_MAX, max);
-                nbits = MAX(DH_GRP_MIN, nbits);
-                nbits = MIN(DH_GRP_MAX, nbits);
-                break;
-        case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
-                debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
-                if ((r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
-                    (r = sshpkt_get_end(ssh)) != 0)
-                        goto out;
-                kex->nbits = nbits;
-                /* unused for old GEX */
-                kex->min = min = DH_GRP_MIN;
-                kex->max = max = DH_GRP_MAX;
-                break;
-        default:
-                r = SSH_ERR_INVALID_ARGUMENT;
+        debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
+        if ((r = sshpkt_get_u32(ssh, &min)) != 0 ||
+            (r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
+            (r = sshpkt_get_u32(ssh, &max)) != 0 ||
+            (r = sshpkt_get_end(ssh)) != 0)
                 goto out;
-        }
+        kex->nbits = nbits;
+        kex->min = min;
+        kex->max = max;
+        min = MAX(DH_GRP_MIN, min);
+        max = MIN(DH_GRP_MAX, max);
+        nbits = MAX(DH_GRP_MIN, nbits);
+        nbits = MIN(DH_GRP_MAX, nbits);
 
         if (kex->max < kex->min || kex->nbits < kex->min ||
             kex->max < kex->nbits) {
@@ -131,10 +112,6 @@ input_kex_dh_gex_request(int type, u_int32_t seq, void *ctxt)
         if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
                 goto out;
 
-        /* old KEX does not use min/max in kexgex_hash() */
-        if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
-                kex->min = kex->max = -1;
-
         debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
         ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_INIT, &input_kex_dh_gex_init);
         r = 0;