Reject if the ALPN callback returned an empty protocol.
If the callback returns an empty ALPN, we forget we negotiated ALPN at
all (bssl::Array does not distinguish null and empty). Empty ALPN
protocols are forbidden anyway, so reject these ahead of time.
Change-Id: I42f1fc4c843bc865e23fb2a2e5d57424b569ee99
Reviewed-on: https://boringssl-review.googlesource.com/28546
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/t1_lib.cc b/ssl/t1_lib.cc
index 7fae0da..40b7ff0 100644
--- a/ssl/t1_lib.cc
+++ b/ssl/t1_lib.cc
@@ -1532,6 +1532,11 @@
ssl, &selected, &selected_len, CBS_data(&protocol_name_list),
CBS_len(&protocol_name_list),
ssl->ctx->alpn_select_cb_arg) == SSL_TLSEXT_ERR_OK) {
+ if (selected_len == 0) {
+ OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
+ *out_alert = SSL_AD_INTERNAL_ERROR;
+ return false;
+ }
if (!ssl->s3->alpn_selected.CopyFrom(
MakeConstSpan(selected, selected_len))) {
*out_alert = SSL_AD_INTERNAL_ERROR;
