Enforce the server ALPN protocol was advertised.
The server should not be allowed select a protocol that wasn't
advertised. Callers tend to not really notice and act as if some default
were chosen which is unlikely to work very well.
Change-Id: Ib6388db72f05386f854d275bab762ca79e8174e6
Reviewed-on: https://boringssl-review.googlesource.com/10284
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 62f3824..5e790a4 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -1517,6 +1517,32 @@
return 0;
}
+ /* Check that the protcol name is one of the ones we advertised. */
+ int protocol_ok = 0;
+ CBS client_protocol_name_list, client_protocol_name;
+ CBS_init(&client_protocol_name_list, ssl->alpn_client_proto_list,
+ ssl->alpn_client_proto_list_len);
+ while (CBS_len(&client_protocol_name_list) > 0) {
+ if (!CBS_get_u8_length_prefixed(&client_protocol_name_list,
+ &client_protocol_name)) {
+ *out_alert = SSL_AD_INTERNAL_ERROR;
+ return 0;
+ }
+
+ if (CBS_len(&client_protocol_name) == CBS_len(&protocol_name) &&
+ memcmp(CBS_data(&client_protocol_name), CBS_data(&protocol_name),
+ CBS_len(&protocol_name)) == 0) {
+ protocol_ok = 1;
+ break;
+ }
+ }
+
+ if (!protocol_ok) {
+ OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
+ *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+ return 0;
+ }
+
if (!CBS_stow(&protocol_name, &ssl->s3->alpn_selected,
&ssl->s3->alpn_selected_len)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
