1 files changed, 69 insertions, 13 deletions

diff --git a/src/lib/libssl/ssl_tlsext.c b/src/lib/libssl/ssl_tlsext.c
index d0764af3c0..0e3ef7da15 100644
--- a/src/lib/libssl/ssl_tlsext.c
+++ b/src/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.19 2018/01/27 15:17:13 jsing Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.20 2018/01/27 15:30:05 jsing Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -1292,6 +1292,35 @@ static struct tls_extension tls_extensions[] = {
 
 #define N_TLS_EXTENSIONS (sizeof(tls_extensions) / sizeof(*tls_extensions))
 
+/* Ensure that extensions fit in a uint32_t bitmask. */
+CTASSERT(N_TLS_EXTENSIONS <= (sizeof(uint32_t) * 8));
+
+static struct tls_extension *
+tls_extension_find(uint16_t type, size_t *tls_extensions_idx)
+{
+        size_t i;
+
+        for (i = 0; i < N_TLS_EXTENSIONS; i++) {
+                if (tls_extensions[i].type == type) {
+                        *tls_extensions_idx = i;
+                        return &tls_extensions[i];
+                }
+        }
+
+        return NULL;
+}
+
+static void
+tlsext_clienthello_reset_state(SSL *s)
+{
+        s->internal->servername_done = 0;
+        s->tlsext_status_type = -1;
+        S3I(s)->renegotiate_seen = 0;
+        free(S3I(s)->alpn_selected);
+        S3I(s)->alpn_selected = NULL;
+        s->internal->srtp_profile = NULL;
+}
+
 int
 tlsext_clienthello_build(SSL *s, CBB *cbb)
 {
@@ -1329,28 +1358,55 @@ tlsext_clienthello_build(SSL *s, CBB *cbb)
 }
 
 int
-tlsext_clienthello_parse_one(SSL *s, CBS *cbs, uint16_t type, int *alert)
+tlsext_clienthello_parse(SSL *s, CBS *cbs, int *alert)
 {
+        CBS extensions, extension_data;
         struct tls_extension *tlsext;
-        size_t i;
+        uint32_t extensions_seen = 0;
+        uint16_t type;
+        size_t idx;
 
-        for (i = 0; i < N_TLS_EXTENSIONS; i++) {
-                tlsext = &tls_extensions[i];
+        /* XXX - this possibly should be done by the caller... */
+        tlsext_clienthello_reset_state(s);
 
-                if (tlsext->type != type)
+        /* An empty extensions block is valid. */
+        if (CBS_len(cbs) == 0)
+                return 1;
+
+        *alert = SSL_AD_DECODE_ERROR;
+
+        if (!CBS_get_u16_length_prefixed(cbs, &extensions))
+                return 0;
+
+        while (CBS_len(&extensions) > 0) {
+                if (!CBS_get_u16(&extensions, &type))
+                        return 0;
+                if (!CBS_get_u16_length_prefixed(&extensions, &extension_data))
+                        return 0;
+
+                if (s->internal->tlsext_debug_cb != NULL)
+                        s->internal->tlsext_debug_cb(s, 0, type,
+                            (unsigned char *)CBS_data(&extension_data),
+                            CBS_len(&extension_data),
+                            s->internal->tlsext_debug_arg);
+
+                /* Unknown extensions are ignored. */
+                if ((tlsext = tls_extension_find(type, &idx)) == NULL)
                         continue;
-                if (!tlsext->clienthello_parse(s, cbs, alert))
+
+                /* Check for duplicate extensions. */
+                if ((extensions_seen & (1 << idx)) != 0)
                         return 0;
-                if (CBS_len(cbs) != 0) {
-                        *alert = SSL_AD_DECODE_ERROR;
+                extensions_seen |= (1 << idx);
+
+                if (!tlsext->clienthello_parse(s, &extension_data, alert))
                         return 0;
-                }
 
-                return 1;
+                if (CBS_len(&extension_data) != 0)
+                        return 0;
         }
 
-        /* Not found. */
-        return 2;
+        return 1;
 }
 
 int