Convert tls1_alpn_handle_client_hello() to CBS.

tweak + ok miod@ jsing@

2 files changed, 28 insertions, 40 deletions

diff --git a/src/lib/libssl/src/ssl/t1_lib.c b/src/lib/libssl/src/ssl/t1_lib.c
index fd423a9135..e901a901da 100644
--- a/src/lib/libssl/src/ssl/t1_lib.c
+++ b/src/lib/libssl/src/ssl/t1_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: t1_lib.c,v 1.77 2015/06/17 07:52:22 doug Exp $ */
+/* $OpenBSD: t1_lib.c,v 1.78 2015/06/19 01:38:54 doug Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1153,10 +1153,9 @@ static int
 tls1_alpn_handle_client_hello(SSL *s, const unsigned char *data,
     unsigned int data_len, int *al)
 {
+        CBS cbs, proto_name_list, alpn;
         const unsigned char *selected;
         unsigned char selected_len;
-        unsigned int proto_len;
-        unsigned int i;
         int r;
 
         if (s->ctx->alpn_select_cb == NULL)
@@ -1165,34 +1164,29 @@ tls1_alpn_handle_client_hello(SSL *s, const unsigned char *data,
         if (data_len < 2)
                 goto parse_error;
 
+        CBS_init(&cbs, data, data_len);
+
         /*
          * data should contain a uint16 length followed by a series of 8-bit,
          * length-prefixed strings.
          */
-        i = ((unsigned int)data[0]) << 8 | ((unsigned int)data[1]);
-        data_len -= 2;
-        data += 2;
-        if (data_len != i)
-                goto parse_error;
-
-        if (data_len < 2)
+        if (!CBS_get_u16_length_prefixed(&cbs, &alpn) ||
+            CBS_len(&alpn) < 2 ||
+            CBS_len(&cbs) != 0)
                 goto parse_error;
 
-        for (i = 0; i < data_len; ) {
-                proto_len = data[i];
-                i++;
-
-                if (proto_len == 0)
-                        goto parse_error;
+        /* Validate data before sending to callback. */
+        CBS_dup(&alpn, &proto_name_list);
+        while (CBS_len(&proto_name_list) > 0) {
+                CBS proto_name;
 
-                if (i + proto_len < i || i + proto_len > data_len)
+                if (!CBS_get_u8_length_prefixed(&proto_name_list, &proto_name) ||
+                    CBS_len(&proto_name) == 0)
                         goto parse_error;
-
-                i += proto_len;
         }
 
         r = s->ctx->alpn_select_cb(s, &selected, &selected_len,
-            data, data_len, s->ctx->alpn_select_cb_arg);
+            CBS_data(&alpn), CBS_len(&alpn), s->ctx->alpn_select_cb_arg);
         if (r == SSL_TLSEXT_ERR_OK) {
                 free(s->s3->alpn_selected);
                 if ((s->s3->alpn_selected = malloc(selected_len)) == NULL) {
diff --git a/src/lib/libssl/t1_lib.c b/src/lib/libssl/t1_lib.c
index fd423a9135..e901a901da 100644
--- a/src/lib/libssl/t1_lib.c
+++ b/src/lib/libssl/t1_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: t1_lib.c,v 1.77 2015/06/17 07:52:22 doug Exp $ */
+/* $OpenBSD: t1_lib.c,v 1.78 2015/06/19 01:38:54 doug Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1153,10 +1153,9 @@ static int
 tls1_alpn_handle_client_hello(SSL *s, const unsigned char *data,
     unsigned int data_len, int *al)
 {
+        CBS cbs, proto_name_list, alpn;
         const unsigned char *selected;
         unsigned char selected_len;
-        unsigned int proto_len;
-        unsigned int i;
         int r;
 
         if (s->ctx->alpn_select_cb == NULL)
@@ -1165,34 +1164,29 @@ tls1_alpn_handle_client_hello(SSL *s, const unsigned char *data,
         if (data_len < 2)
                 goto parse_error;
 
+        CBS_init(&cbs, data, data_len);
+
         /*
          * data should contain a uint16 length followed by a series of 8-bit,
          * length-prefixed strings.
          */
-        i = ((unsigned int)data[0]) << 8 | ((unsigned int)data[1]);
-        data_len -= 2;
-        data += 2;
-        if (data_len != i)
-                goto parse_error;
-
-        if (data_len < 2)
+        if (!CBS_get_u16_length_prefixed(&cbs, &alpn) ||
+            CBS_len(&alpn) < 2 ||
+            CBS_len(&cbs) != 0)
                 goto parse_error;
 
-        for (i = 0; i < data_len; ) {
-                proto_len = data[i];
-                i++;
-
-                if (proto_len == 0)
-                        goto parse_error;
+        /* Validate data before sending to callback. */
+        CBS_dup(&alpn, &proto_name_list);
+        while (CBS_len(&proto_name_list) > 0) {
+                CBS proto_name;
 
-                if (i + proto_len < i || i + proto_len > data_len)
+                if (!CBS_get_u8_length_prefixed(&proto_name_list, &proto_name) ||
+                    CBS_len(&proto_name) == 0)
                         goto parse_error;
-
-                i += proto_len;
         }
 
         r = s->ctx->alpn_select_cb(s, &selected, &selected_len,
-            data, data_len, s->ctx->alpn_select_cb_arg);
+            CBS_data(&alpn), CBS_len(&alpn), s->ctx->alpn_select_cb_arg);
         if (r == SSL_TLSEXT_ERR_OK) {
                 free(s->s3->alpn_selected);
                 if ((s->s3->alpn_selected = malloc(selected_len)) == NULL) {