1 files changed, 29 insertions, 6 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index f636fb3d9..da8c8229c 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect2.c,v 1.56 2001/03/26 08:07:09 markus Exp $");
+RCSID("$OpenBSD: sshconnect2.c,v 1.57 2001/03/27 17:46:49 provos Exp $");
 
 #include <openssl/bn.h>
 #include <openssl/md5.h>
@@ -46,6 +46,7 @@ RCSID("$OpenBSD: sshconnect2.c,v 1.56 2001/03/26 08:07:09 markus Exp $");
 #include "sshconnect.h"
 #include "authfile.h"
 #include "cli.h"
+#include "dh.h"
 #include "dispatch.h"
 #include "authfd.h"
 #include "log.h"
@@ -309,7 +310,7 @@ ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
         int plen, dlen;
         u_int klen, kout;
         char *signature = NULL;
-        u_int slen, nbits;
+        u_int slen, nbits, min, max;
         char *server_host_key_blob = NULL;
         Key *server_host_key;
         u_int sbloblen;
@@ -322,14 +323,31 @@ ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
 
         nbits = dh_estimate(kex->we_need * 8);
 
-        debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST.");
-        packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
-        packet_put_int(nbits);
+        if (datafellows & SSH_OLD_DHGEX) {
+                debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST_OLD.");
+
+                /* Old GEX request */
+                packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
+                packet_put_int(nbits);
+                min = DH_GRP_MIN;
+                max = DH_GRP_MAX;
+        } else {
+                debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST.");
+
+                /* New GEX request */
+                min = DH_GRP_MIN;
+                max = MIN(DH_GRP_MAX, nbits * 1.25);
+
+                packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
+                packet_put_int(min);
+                packet_put_int(nbits);
+                packet_put_int(max);
+        }
         packet_send();
         packet_write_wait();
 
 #ifdef DEBUG_KEXDH
-        fprintf(stderr, "\nnbits = %d", nbits);
+        fprintf(stderr, "\nmin = %d, nbits = %d, max = %d", min, nbits, max);
 #endif
 
         debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP.");
@@ -344,6 +362,11 @@ ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
         if ((g = BN_new()) == NULL)
                 fatal("BN_new");
         packet_get_bignum2(g, &dlen);
+
+        if (BN_num_bits(p) < min || BN_num_bits(p) > max)
+                fatal("DH_GEX group out of range: %d !< %d !< %d",
+                    min, BN_num_bits(p), max);
+
         dh = dh_new_group(g, p);
 
         dh_gen_key(dh, kex->we_need * 8);