merge of '5fdf69ca60d1683cdd9f4c2595134bed26394834'

     and '6b61c50f4cf888bea302ac8fcf5dbb573b443251'

--HG--
extra : convert_revision : b1dd3b94e60a07a176dba2b035ac79968595990a

1 files changed, 10 insertions, 6 deletions

diff --git a/common-session.c b/common-session.c
index e8dc650..b8ea6f7 100644
--- a/common-session.c
+++ b/common-session.c
@@ -229,13 +229,11 @@ void session_identification() {
 	/* write our version string, this blocks */
 	if (atomicio(write, ses.sock, LOCAL_IDENT "\r\n",
 				strlen(LOCAL_IDENT "\r\n")) == DROPBEAR_FAILURE) {
-		dropbear_exit("Error writing ident string");
+		ses.remoteclosed();
 	}
 
-	/* 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) {
@@ -252,13 +250,19 @@ void session_identification() {
 
 	if (!done) {
 		TRACE(("err: %s for '%s'\n", strerror(errno), linebuf))
-		dropbear_exit("Failed to get remote version");
+		ses.remoteclosed();
 	} else {
 		/* linebuf is already null terminated */
 		ses.remoteident = m_malloc(len);
 		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))
 
 }