Allow a client to send early_data with SNI if the session has no SNI

We can only send early_data if the SNI is consistent. However it is valid
for the client to set SNI and the server to not use it. This would still be
counted as consistent. OpenSSL client was being overzealous in this check
and disallowing this scenario.

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4738)

diff --git a/ssl/statem/extensions_clnt.c b/ssl/statem/extensions_clnt.c
index a69075122238556a1ccb7923ab0fb88b8835f35c..0dc1c49734ede1d7345d434a1b4af8a519aa2401 100644 (file)
--- a/ssl/statem/extensions_clnt.c
+++ b/ssl/statem/extensions_clnt.c
@@ -736,13 +736,14 @@ EXT_RETURN tls_construct_ctos_early_data(SSL *s, WPACKET *pkt,
     edsess = s->session->ext.max_early_data != 0 ? s->session : psksess;
     s->max_early_data = edsess->ext.max_early_data;
 
-    if ((s->ext.hostname == NULL && edsess->ext.hostname != NULL)
-            || (s->ext.hostname != NULL
-                && (edsess->ext.hostname == NULL
-                    || strcmp(s->ext.hostname, edsess->ext.hostname) != 0))) {
-        SSLerr(SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA,
-               SSL_R_INCONSISTENT_EARLY_DATA_SNI);
-        return EXT_RETURN_FAIL;
+    if (edsess->ext.hostname != NULL) {
+        if (s->ext.hostname == NULL
+                || (s->ext.hostname != NULL
+                    && strcmp(s->ext.hostname, edsess->ext.hostname) != 0)) {
+            SSLerr(SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA,
+                   SSL_R_INCONSISTENT_EARLY_DATA_SNI);
+            return EXT_RETURN_FAIL;
+        }
     }
 
     if ((s->ext.alpn == NULL && edsess->ext.alpn_selected != NULL)) {