add some comments about better handling first-KEX-follows notifications

from the server. Nothing uses these right now. No binary change

1 files changed, 13 insertions, 3 deletions

diff --git a/usr.bin/ssh/kex.c b/usr.bin/ssh/kex.c
index 2c04c5899b4..87ccd6bf78e 100644
--- a/usr.bin/ssh/kex.c
+++ b/usr.bin/ssh/kex.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.86 2010/09/22 05:01:29 djm Exp $ */
+/* $OpenBSD: kex.c,v 1.87 2012/08/17 01:22:56 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
@@ -231,8 +231,18 @@ kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
 		packet_get_char();
 	for (i = 0; i < PROPOSAL_MAX; i++)
 		xfree(packet_get_string(NULL));
-	(void) packet_get_char();
-	(void) packet_get_int();
+	/*
+	 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
+	 * KEX method has the server move first, but a server might be using
+	 * a custom method or one that we otherwise don't support. We should
+	 * be prepared to remember first_kex_follows here so we can eat a
+	 * packet later.
+	 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
+	 * for cases where the server *doesn't* go first. I guess we should
+	 * ignore it when it is set for these cases, which is what we do now.
+	 */
+	(void) packet_get_char();	/* first_kex_follows */
+	(void) packet_get_int();	/* reserved */
 	packet_check_eom();
 
 	kex_kexinit_finish(kex);