From b5989964979e3ee885eeb6d0758d96605b131a7b Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Sat, 4 Mar 2006 08:22:16 +0000
Subject: [PATCH] Exit with a message if the ssh protocol version is
incompatible
--HG--
extra : convert_revision : 5d396842815593611f0d61762440145d1fc74d5a
---
common-session.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/common-session.c b/common-session.c
index e8dc6502..4c15391e 100644
--- a/common-session.c
+++ b/common-session.c
@@ -232,10 +232,8 @@ void session_identification() {
dropbear_exit("Error writing ident string");
}
- /* We allow up to 9 lines before the actual version string, to
- * account for wrappers/cruft etc. According to the spec only the client
- * needs to handle this, but no harm in letting the server handle it too */
- for (i = 0; i < 10; i++) {
+ /* If they send more than 50 lines, something is wrong */
+ for (i = 0; i < 50; i++) {
len = ident_readln(ses.sock, linebuf, sizeof(linebuf));
if (len < 0 && errno != EINTR) {
@@ -259,6 +257,12 @@ void session_identification() {
memcpy(ses.remoteident, linebuf, len);
}
+ /* Shall assume that 2.x will be backwards compatible. */
+ if (strncmp(ses.remoteident, "SSH-2.", 6) != 0
+ && strncmp(ses.remoteident, "SSH-1.99-", 9) != 0) {
+ dropbear_exit("Incompatible remote version '%s'", ses.remoteident);
+ }
+
TRACE(("remoteident: %s", ses.remoteident))
}
--
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