Don't send an alert if we've just received one

If the record received is for a version that we don't support, previously we
were sending an alert back. However if the incoming record already looks
like an alert then probably we shouldn't do that. So suppress an outgoing
alert if it looks like we've got one incoming.

Reviewed-by: Kurt Roeckx <kurt@openssl.org>

diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.c
index 7c9f20c8f99e379d75e067945e49b9678bbaa867..25cf929a55d6decf3d815f28ab5e3ffd8d089b11 100644 (file)
--- a/ssl/s3_pkt.c
+++ b/ssl/s3_pkt.c
@@ -347,11 +347,22 @@ static int ssl3_get_record(SSL *s)
             if (version != s->version) {
                 SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_WRONG_VERSION_NUMBER);
                 if ((s->version & 0xFF00) == (version & 0xFF00)
-                    && !s->enc_write_ctx && !s->write_hash)
+                    && !s->enc_write_ctx && !s->write_hash) {
+                    if (rr->type == SSL3_RT_ALERT) {
+                        /*
+                         * The record is using an incorrect version number, but
+                         * what we've got appears to be an alert. We haven't
+                         * read the body yet to check whether its a fatal or
+                         * not - but chances are it is. We probably shouldn't
+                         * send a fatal alert back. We'll just end.
+                         */
+                         goto err;
+                    }
                     /*
                      * Send back error using their minor version number :-)
                      */
                     s->version = (unsigned short)version;
+                }
                 al = SSL_AD_PROTOCOL_VERSION;
                 goto f_err;
             }