From: Matt Caswell <matt@openssl.org>
Date: Tue, 14 Nov 2017 13:55:21 +0000 (+0000)
Subject: Allow a client to send early_data with SNI if the session has no SNI
X-Git-Tag: OpenSSL_1_1_1-pre1~423
X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=bfab12bb7dbd32cb13a8d518f312857ebd045541

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 a690751222..0dc1c49734 100644
--- 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)) {