1 files changed, 30 insertions, 28 deletions

diff --git a/src/lib/libssl/ssl_lib.c b/src/lib/libssl/ssl_lib.c
index f5d477e864..d78cb2ac3a 100644
--- a/src/lib/libssl/ssl_lib.c
+++ b/src/lib/libssl/ssl_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_lib.c,v 1.325 2024/06/29 07:34:12 tb Exp $ */
+/* $OpenBSD: ssl_lib.c,v 1.326 2024/07/11 13:48:52 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1791,56 +1791,58 @@ LSSL_ALIAS(SSL_get_servername_type);
  */
 int
 SSL_select_next_proto(unsigned char **out, unsigned char *outlen,
-    const unsigned char *server_list, unsigned int server_list_len,
-    const unsigned char *client_list, unsigned int client_list_len)
+    const unsigned char *peer_list, unsigned int peer_list_len,
+    const unsigned char *supported_list, unsigned int supported_list_len)
 {
-        CBS client, client_proto, server, server_proto;
+        CBS peer, peer_proto, supported, supported_proto;
 
         *out = NULL;
         *outlen = 0;
 
-        /* First check that the client list is well-formed. */
-        CBS_init(&client, client_list, client_list_len);
-        if (!tlsext_alpn_check_format(&client))
+        /* First check that the supported list is well-formed. */
+        CBS_init(&supported, supported_list, supported_list_len);
+        if (!tlsext_alpn_check_format(&supported))
                 goto err;
 
         /*
-         * Use first client protocol as fallback. This is one way of doing NPN's
-         * "opportunistic" protocol selection (see security considerations in
-         * draft-agl-tls-nextprotoneg-04), and it is the documented behavior of
-         * this API. For ALPN it's the callback's responsibility to fail on
+         * Use first supported protocol as fallback. This is one way of doing
+         * NPN's "opportunistic" protocol selection (see security considerations
+         * in draft-agl-tls-nextprotoneg-04), and it is the documented behavior
+         * of this API. For ALPN it's the callback's responsibility to fail on
          * OPENSSL_NPN_NO_OVERLAP.
          */
 
-        if (!CBS_get_u8_length_prefixed(&client, &client_proto))
+        if (!CBS_get_u8_length_prefixed(&supported, &supported_proto))
                 goto err;
 
-        *out = (unsigned char *)CBS_data(&client_proto);
-        *outlen = CBS_len(&client_proto);
+        *out = (unsigned char *)CBS_data(&supported_proto);
+        *outlen = CBS_len(&supported_proto);
 
-        /* Now check that the server list is well-formed. */
-        CBS_init(&server, server_list, server_list_len);
-        if (!tlsext_alpn_check_format(&server))
+        /* Now check that the peer list is well-formed. */
+        CBS_init(&peer, peer_list, peer_list_len);
+        if (!tlsext_alpn_check_format(&peer))
                 goto err;
 
         /*
-         * Walk the server list and select the first protocol that appears in
-         * the client list.
+         * Walk the peer list and select the first protocol that appears in
+         * the supported list. Thus we honor peer preference rather than local
+         * preference contrary to a SHOULD in RFC 7301, section 3.2.
          */
-        while (CBS_len(&server) > 0) {
-                if (!CBS_get_u8_length_prefixed(&server, &server_proto))
+        while (CBS_len(&peer) > 0) {
+                if (!CBS_get_u8_length_prefixed(&peer, &peer_proto))
                         goto err;
 
-                CBS_init(&client, client_list, client_list_len);
+                CBS_init(&supported, supported_list, supported_list_len);
 
-                while (CBS_len(&client) > 0) {
-                        if (!CBS_get_u8_length_prefixed(&client, &client_proto))
+                while (CBS_len(&supported) > 0) {
+                        if (!CBS_get_u8_length_prefixed(&supported,
+                            &supported_proto))
                                 goto err;
 
-                        if (CBS_mem_equal(&client_proto,
-                            CBS_data(&server_proto), CBS_len(&server_proto))) {
-                                *out = (unsigned char *)CBS_data(&server_proto);
-                                *outlen = CBS_len(&server_proto);
+                        if (CBS_mem_equal(&supported_proto,
+                            CBS_data(&peer_proto), CBS_len(&peer_proto))) {
+                                *out = (unsigned char *)CBS_data(&peer_proto);
+                                *outlen = CBS_len(&peer_proto);
 
                                 return OPENSSL_NPN_NEGOTIATED;
                         }