upstream commit

Improve printing of KEX offers and decisions

The debug output now labels the client and server offers and the
negotiated options. ok markus@

Upstream-ID: 8db921b3f92a4565271b1c1fbce6e7f508e1a2cb

1 files changed, 38 insertions, 19 deletions

diff --git a/kex.c b/kex.c
index 5100c661d..5f72f2e9f 100644
--- a/kex.c
+++ b/kex.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.109 2015/07/30 00:01:34 djm Exp $ */
+/* $OpenBSD: kex.c,v 1.110 2015/08/21 23:57:48 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
@@ -67,6 +67,19 @@ extern const EVP_MD *evp_ssh_sha256(void);
 static int kex_choose_conf(struct ssh *);
 static int kex_input_newkeys(int, u_int32_t, void *);
 
+static const char *proposal_names[PROPOSAL_MAX] = {
+        "KEX algorithms",
+        "host key algorithms",
+        "ciphers ctos",
+        "ciphers stoc",
+        "MACs ctos",
+        "MACs stoc",
+        "compression ctos",
+        "compression stoc",
+        "languages ctos",
+        "languages stoc",
+};
+
 struct kexalg {
         char *name;
         u_int type;
@@ -267,7 +280,7 @@ kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
         for (i = 0; i < PROPOSAL_MAX; i++) {
                 if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0)
                         goto out;
-                debug2("kex_parse_kexinit: %s", proposal[i]);
+                debug2("%s: %s", proposal_names[i], proposal[i]);
         }
         /* first kex follows / reserved */
         if ((r = sshbuf_get_u8(b, &v)) != 0 ||
@@ -275,8 +288,8 @@ kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
                 goto out;
         if (first_kex_follows != NULL)
                 *first_kex_follows = i;
-        debug2("kex_parse_kexinit: first_kex_follows %d ", v);
-        debug2("kex_parse_kexinit: reserved %u ", i);
+        debug2("first_kex_follows %d ", v);
+        debug2("reserved %u ", i);
         r = 0;
         *propp = proposal;
  out:
@@ -593,6 +606,7 @@ choose_kex(struct kex *k, char *client, char *server)
 
         k->name = match_list(client, server, NULL);
 
+        debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
         if (k->name == NULL)
                 return SSH_ERR_NO_KEX_ALG_MATCH;
         if ((kexalg = kex_alg_by_name(k->name)) == NULL)
@@ -608,6 +622,8 @@ choose_hostkeyalg(struct kex *k, char *client, char *server)
 {
         char *hostkeyalg = match_list(client, server, NULL);
 
+        debug("kex: host key algorithm: %s",
+            hostkeyalg ? hostkeyalg : "(no match)");
         if (hostkeyalg == NULL)
                 return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
         k->hostkey_type = sshkey_type_from_name(hostkeyalg);
@@ -653,8 +669,11 @@ kex_choose_conf(struct ssh *ssh)
         u_int mode, ctos, need, dh_need, authlen;
         int r, first_kex_follows;
 
-        if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0 ||
-            (r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
+        debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
+        if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
+                goto out;
+        debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
+        if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
                 goto out;
 
         if (kex->server) {
@@ -677,6 +696,18 @@ kex_choose_conf(struct ssh *ssh)
         }
 
         /* Algorithm Negotiation */
+        if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
+            sprop[PROPOSAL_KEX_ALGS])) != 0) {
+                kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
+                peer[PROPOSAL_KEX_ALGS] = NULL;
+                goto out;
+        }
+        if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
+            sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
+                kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
+                peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
+                goto out;
+        }
         for (mode = 0; mode < MODE_MAX; mode++) {
                 if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
                         r = SSH_ERR_ALLOC_FAIL;
@@ -709,24 +740,12 @@ kex_choose_conf(struct ssh *ssh)
                         peer[ncomp] = NULL;
                         goto out;
                 }
-                debug("kex: %s %s %s %s",
+                debug("kex: %s cipher: %s MAC: %s compression: %s",
                     ctos ? "client->server" : "server->client",
                     newkeys->enc.name,
                     authlen == 0 ? newkeys->mac.name : "<implicit>",
                     newkeys->comp.name);
         }
-        if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
-            sprop[PROPOSAL_KEX_ALGS])) != 0) {
-                kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
-                peer[PROPOSAL_KEX_ALGS] = NULL;
-                goto out;
-        }
-        if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
-            sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
-                kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
-                peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
-                goto out;
-        }
         need = dh_need = 0;
         for (mode = 0; mode < MODE_MAX; mode++) {
                 newkeys = kex->newkeys[mode];