Add ALPN support patch
This change adds support for ALPN[1] in OpenSSL. ALPN is the IETF
blessed version of NPN and we'll be supporting both ALPN and NPN for
some time yet.
[1] https://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg-00
Patch from Adam Langley <agl@chromium.org>
Change-Id: I556b1ee877f398ae8b7f1d4abbaddc44611e5f51
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 53b805f..f170056 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -659,6 +659,18 @@
s2n(0,ret);
}
+ if (s->alpn_client_proto_list && !s->s3->tmp.finish_md_len)
+ {
+ if ((size_t)(limit - ret) < 6 + s->alpn_client_proto_list_len)
+ return NULL;
+ s2n(TLSEXT_TYPE_application_layer_protocol_negotiation,ret);
+ s2n(2 + s->alpn_client_proto_list_len,ret);
+ s2n(s->alpn_client_proto_list_len,ret);
+ memcpy(ret, s->alpn_client_proto_list,
+ s->alpn_client_proto_list_len);
+ ret += s->alpn_client_proto_list_len;
+ }
+
#ifndef OPENSSL_NO_SRTP
if(SSL_get_srtp_profiles(s))
{
@@ -879,6 +891,21 @@
s2n(0,ret);
}
+ if (s->s3->alpn_selected)
+ {
+ const unsigned char *selected = s->s3->alpn_selected;
+ unsigned len = s->s3->alpn_selected_len;
+
+ if ((long)(limit - ret - 4 - 2 - 1 - len) < 0)
+ return NULL;
+ s2n(TLSEXT_TYPE_application_layer_protocol_negotiation,ret);
+ s2n(3 + len,ret);
+ s2n(1 + len,ret);
+ *ret++ = len;
+ memcpy(ret, selected, len);
+ ret += len;
+ }
+
if ((extdatalen = ret-p-2)== 0)
return p;
@@ -886,6 +913,76 @@
return ret;
}
+/* tls1_alpn_handle_client_hello is called to process the ALPN extension in a
+ * ClientHello.
+ * data: the contents of the extension, not including the type and length.
+ * data_len: the number of bytes in |data|
+ * al: a pointer to the alert value to send in the event of a non-zero
+ * return.
+ *
+ * returns: 0 on success. */
+static int tls1_alpn_handle_client_hello(SSL *s, const unsigned char *data,
+ unsigned data_len, int *al)
+ {
+ unsigned i;
+ unsigned proto_len;
+ const unsigned char *selected;
+ unsigned char selected_len;
+ int r;
+
+ if (s->ctx->alpn_select_cb == NULL)
+ return 0;
+
+ if (data_len < 2)
+ goto parse_error;
+
+ /* data should contain a uint16 length followed by a series of 8-bit,
+ * length-prefixed strings. */
+ i = ((unsigned) data[0]) << 8 |
+ ((unsigned) data[1]);
+ data_len -= 2;
+ data += 2;
+ if (data_len != i)
+ goto parse_error;
+
+ if (data_len < 2)
+ goto parse_error;
+
+ for (i = 0; i < data_len;)
+ {
+ proto_len = data[i];
+ i++;
+
+ if (proto_len == 0)
+ goto parse_error;
+
+ if (i + proto_len < i || i + proto_len > data_len)
+ 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);
+ if (r == SSL_TLSEXT_ERR_OK) {
+ if (s->s3->alpn_selected)
+ OPENSSL_free(s->s3->alpn_selected);
+ s->s3->alpn_selected = OPENSSL_malloc(selected_len);
+ if (!s->s3->alpn_selected)
+ {
+ *al = SSL_AD_INTERNAL_ERROR;
+ return -1;
+ }
+ memcpy(s->s3->alpn_selected, selected, selected_len);
+ s->s3->alpn_selected_len = selected_len;
+ }
+ return 0;
+
+parse_error:
+ *al = SSL_AD_DECODE_ERROR;
+ return -1;
+ }
+
int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, int n, int *al)
{
unsigned short type;
@@ -908,6 +1005,12 @@
s->s3->next_proto_neg_seen = 0;
#endif
+ if (s->s3->alpn_selected)
+ {
+ OPENSSL_free(s->s3->alpn_selected);
+ s->s3->alpn_selected = NULL;
+ }
+
#ifndef OPENSSL_NO_HEARTBEATS
s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED |
SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
@@ -1334,7 +1437,8 @@
#endif
#ifndef OPENSSL_NO_NEXTPROTONEG
else if (type == TLSEXT_TYPE_next_proto_neg &&
- s->s3->tmp.finish_md_len == 0)
+ s->s3->tmp.finish_md_len == 0 &&
+ s->s3->alpn_selected == NULL)
{
/* We shouldn't accept this extension on a
* renegotiation.
@@ -1358,6 +1462,16 @@
else if (type == TLSEXT_TYPE_channel_id && s->tlsext_channel_id_enabled)
s->s3->tlsext_channel_id_valid = 1;
+ else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation &&
+ s->ctx->alpn_select_cb &&
+ s->s3->tmp.finish_md_len == 0)
+ {
+ if (tls1_alpn_handle_client_hello(s, data, size, al) != 0)
+ return 0;
+ /* ALPN takes precedence over NPN. */
+ s->s3->next_proto_neg_seen = 0;
+ }
+
/* session ticket processed earlier */
#ifndef OPENSSL_NO_SRTP
else if (type == TLSEXT_TYPE_use_srtp)
@@ -1422,6 +1536,12 @@
s->s3->next_proto_neg_seen = 0;
#endif
+ if (s->s3->alpn_selected)
+ {
+ OPENSSL_free(s->s3->alpn_selected);
+ s->s3->alpn_selected = NULL;
+ }
+
#ifndef OPENSSL_NO_HEARTBEATS
s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED |
SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
@@ -1591,6 +1711,51 @@
else if (type == TLSEXT_TYPE_channel_id)
s->s3->tlsext_channel_id_valid = 1;
+ else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation)
+ {
+ unsigned len;
+
+ /* We must have requested it. */
+ if (s->alpn_client_proto_list == NULL)
+ {
+ *al = TLS1_AD_UNSUPPORTED_EXTENSION;
+ return 0;
+ }
+ if (size < 4)
+ {
+ *al = TLS1_AD_DECODE_ERROR;
+ return 0;
+ }
+ /* The extension data consists of:
+ * uint16 list_length
+ * uint8 proto_length;
+ * uint8 proto[proto_length]; */
+ len = data[0];
+ len <<= 8;
+ len |= data[1];
+ if (len != (unsigned) size - 2)
+ {
+ *al = TLS1_AD_DECODE_ERROR;
+ return 0;
+ }
+ len = data[2];
+ if (len != (unsigned) size - 3)
+ {
+ *al = TLS1_AD_DECODE_ERROR;
+ return 0;
+ }
+ if (s->s3->alpn_selected)
+ OPENSSL_free(s->s3->alpn_selected);
+ s->s3->alpn_selected = OPENSSL_malloc(len);
+ if (!s->s3->alpn_selected)
+ {
+ *al = TLS1_AD_INTERNAL_ERROR;
+ return 0;
+ }
+ memcpy(s->s3->alpn_selected, data + 3, len);
+ s->s3->alpn_selected_len = len;
+ }
+
else if (type == TLSEXT_TYPE_renegotiate)
{
if(!ssl_parse_serverhello_renegotiate_ext(s, data, size, al))