Bug 959664: Add ALPN support to NSS, r=briansmithNSS_3_15_5_BETA2

6 files changed, 183 insertions, 5 deletions

diff --git a/lib/ssl/ssl.h b/lib/ssl/ssl.h
index 79987e69a..b27af6658 100644
--- a/lib/ssl/ssl.h
+++ b/lib/ssl/ssl.h
@@ -162,6 +162,25 @@ SSL_IMPORT PRFileDesc *DTLS_ImportFD(PRFileDesc *model, PRFileDesc *fd);
 #define SSL_CBC_RANDOM_IV 23
 #define SSL_ENABLE_OCSP_STAPLING       24 /* Request OCSP stapling (client) */
 
+/* SSL_ENABLE_NPN controls whether the NPN extension is enabled for the initial
+ * handshake when protocol negotiation is used. SSL_SetNextProtoCallback
+ * or SSL_SetNextProtoNego must be used to control the protocol negotiation;
+ * otherwise, the NPN extension will not be negotiated. SSL_ENABLE_NPN is
+ * currently enabled by default but this may change in future versions.
+ */
+#define SSL_ENABLE_NPN 25
+
+/* SSL_ENABLE_ALPN controls whether the ALPN extension is enabled for the
+ * initial handshake when protocol negotiation is used. SSL_SetNextProtoNego
+ * (not SSL_SetNextProtoCallback) must be used to control the protocol
+ * negotiation; otherwise, the ALPN extension will not be negotiated. ALPN is
+ * not negotiated for renegotiation handshakes, even though the ALPN
+ * specification defines a way to use ALPN during renegotiations.
+ * SSL_ENABLE_ALPN is currently disabled by default, but this may change in
+ * future versions.
+ */
+#define SSL_ENABLE_ALPN 26
+
 #ifdef SSL_DEPRECATED_FUNCTION 
 /* Old deprecated function names */
 SSL_IMPORT SECStatus SSL_Enable(PRFileDesc *fd, int option, PRBool on);
@@ -206,6 +225,16 @@ SSL_IMPORT SECStatus SSL_SetNextProtoCallback(PRFileDesc *fd,
  * protocol in server-preference order. If no matching protocol is found it
  * selects the first supported protocol.
  *
+ * Using this function also allows the client to transparently support ALPN.
+ * The same set of protocols will be advertised via ALPN and, if the server
+ * uses ALPN to select a protocol, SSL_GetNextProto will return
+ * SSL_NEXT_PROTO_SELECTED as the state.
+ *
+ * Since NPN uses the first protocol as the fallback protocol, when sending an
+ * ALPN extension, the first protocol is moved to the end of the list. This
+ * indicates that the fallback protocol is the least preferred. The other
+ * protocols should be in preference order.
+ *
  * The supported protocols are specified in |data| in wire-format (8-bit
  * length-prefixed). For example: "\010http/1.1\006spdy/2". */
 SSL_IMPORT SECStatus SSL_SetNextProtoNego(PRFileDesc *fd,
@@ -215,7 +244,8 @@ SSL_IMPORT SECStatus SSL_SetNextProtoNego(PRFileDesc *fd,
 typedef enum SSLNextProtoState { 
   SSL_NEXT_PROTO_NO_SUPPORT = 0, /* No peer support                */
   SSL_NEXT_PROTO_NEGOTIATED = 1, /* Mutual agreement               */
-  SSL_NEXT_PROTO_NO_OVERLAP = 2  /* No protocol overlap found      */
+  SSL_NEXT_PROTO_NO_OVERLAP = 2, /* No protocol overlap found      */
+  SSL_NEXT_PROTO_SELECTED   = 3  /* Server selected proto (ALPN)   */
 } SSLNextProtoState;
 
 /* SSL_GetNextProto can be used in the HandshakeCallback or any time after
diff --git a/lib/ssl/ssl3con.c b/lib/ssl/ssl3con.c
index 9e8d2e41a..cc3030612 100644
--- a/lib/ssl/ssl3con.c
+++ b/lib/ssl/ssl3con.c
@@ -10185,8 +10185,10 @@ ssl3_SendNextProto(sslSocket *ss)
     int padding_len;
     static const unsigned char padding[32] = {0};
 
-    if (ss->ssl3.nextProto.len == 0)
+    if (ss->ssl3.nextProto.len == 0 ||
+	ss->ssl3.nextProtoState == SSL_NEXT_PROTO_SELECTED) {
 	return SECSuccess;
+    }
 
     PORT_Assert( ss->opt.noLocks || ssl_HaveXmitBufLock(ss));
     PORT_Assert( ss->opt.noLocks || ssl_HaveSSL3HandshakeLock(ss));
diff --git a/lib/ssl/ssl3ext.c b/lib/ssl/ssl3ext.c
index d75d458b6..792a3b421 100644
--- a/lib/ssl/ssl3ext.c
+++ b/lib/ssl/ssl3ext.c
@@ -52,8 +52,12 @@ static SECStatus ssl3_HandleRenegotiationInfoXtn(sslSocket *ss,
     PRUint16 ex_type, SECItem *data);
 static SECStatus ssl3_ClientHandleNextProtoNegoXtn(sslSocket *ss,
 			PRUint16 ex_type, SECItem *data);
+static SECStatus ssl3_ClientHandleAppProtoXtn(sslSocket *ss,
+			PRUint16 ex_type, SECItem *data);
 static SECStatus ssl3_ServerHandleNextProtoNegoXtn(sslSocket *ss,
 			PRUint16 ex_type, SECItem *data);
+static PRInt32 ssl3_ClientSendAppProtoXtn(sslSocket *ss, PRBool append,
+					  PRUint32 maxBytes);
 static PRInt32 ssl3_ClientSendNextProtoNegoXtn(sslSocket *ss, PRBool append,
 					       PRUint32 maxBytes);
 static PRInt32 ssl3_SendUseSRTPXtn(sslSocket *ss, PRBool append,
@@ -247,6 +251,7 @@ static const ssl3HelloExtensionHandler serverHelloHandlersTLS[] = {
     { ssl_session_ticket_xtn,     &ssl3_ClientHandleSessionTicketXtn },
     { ssl_renegotiation_info_xtn, &ssl3_HandleRenegotiationInfoXtn },
     { ssl_next_proto_nego_xtn,    &ssl3_ClientHandleNextProtoNegoXtn },
+    { ssl_app_layer_protocol_xtn, &ssl3_ClientHandleAppProtoXtn },
     { ssl_use_srtp_xtn,           &ssl3_HandleUseSRTPXtn },
     { ssl_cert_status_xtn,        &ssl3_ClientHandleStatusRequestXtn },
     { -1, NULL }
@@ -273,6 +278,7 @@ ssl3HelloExtensionSender clientHelloSendersTLS[SSL_MAX_EXTENSIONS] = {
 #endif
     { ssl_session_ticket_xtn,     &ssl3_SendSessionTicketXtn },
     { ssl_next_proto_nego_xtn,    &ssl3_ClientSendNextProtoNegoXtn },
+    { ssl_app_layer_protocol_xtn, &ssl3_ClientSendAppProtoXtn },
     { ssl_use_srtp_xtn,           &ssl3_SendUseSRTPXtn },
     { ssl_cert_status_xtn,        &ssl3_ClientSendStatusRequestXtn },
     { ssl_signature_algorithms_xtn, &ssl3_ClientSendSigAlgsXtn }
@@ -608,6 +614,16 @@ ssl3_ClientHandleNextProtoNegoXtn(sslSocket *ss, PRUint16 ex_type,
 
     PORT_Assert(!ss->firstHsDone);
 
+    if (ssl3_ExtensionNegotiated(ss, ssl_app_layer_protocol_xtn)) {
+	/* If the server negotiated ALPN then it has already told us what protocol
+	 * to use, so it doesn't make sense for us to try to negotiate a different
+	 * one by sending the NPN handshake message. However, if we've negotiated
+	 * NPN then we're required to send the NPN handshake message. Thus, these
+	 * two extensions cannot both be negotiated on the same connection. */
+	PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
+	return SECFailure;
+    }
+
     rv = ssl3_ValidateNextProtoNego(data->data, data->len);
     if (rv != SECSuccess)
 	return rv;
@@ -641,6 +657,43 @@ ssl3_ClientHandleNextProtoNegoXtn(sslSocket *ss, PRUint16 ex_type,
     return SECITEM_CopyItem(NULL, &ss->ssl3.nextProto, &result);
 }
 
+static SECStatus
+ssl3_ClientHandleAppProtoXtn(sslSocket *ss, PRUint16 ex_type, SECItem *data)
+{
+    const unsigned char* d = data->data;
+    PRUint16 name_list_len;
+    SECItem protocol_name;
+
+    if (ssl3_ExtensionNegotiated(ss, ssl_next_proto_nego_xtn)) {
+	PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
+	return SECFailure;
+    }
+
+    /* The extension data from the server has the following format:
+     *   uint16 name_list_len;
+     *   uint8 len;
+     *   uint8 protocol_name[len]; */
+    if (data->len < 4 || data->len > 2 + 1 + 255) {
+	PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
+	return SECFailure;
+    }
+
+    name_list_len = ((PRUint16) d[0]) << 8 |
+	            ((PRUint16) d[1]);
+    if (name_list_len != data->len - 2 || d[2] != data->len - 3) {
+	PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
+	return SECFailure;
+    }
+
+    protocol_name.data = data->data + 3;
+    protocol_name.len = data->len - 3;
+
+    SECITEM_FreeItem(&ss->ssl3.nextProto, PR_FALSE);
+    ss->ssl3.nextProtoState = SSL_NEXT_PROTO_SELECTED;
+    ss->xtnData.negotiated[ss->xtnData.numNegotiated++] = ex_type;
+    return SECITEM_CopyItem(NULL, &ss->ssl3.nextProto, &protocol_name);
+}
+
 static PRInt32
 ssl3_ClientSendNextProtoNegoXtn(sslSocket * ss, PRBool append,
 				PRUint32 maxBytes)
@@ -648,7 +701,7 @@ ssl3_ClientSendNextProtoNegoXtn(sslSocket * ss, PRBool append,
     PRInt32 extension_length;
 
     /* Renegotiations do not send this extension. */
-    if (!ss->nextProtoCallback || ss->firstHsDone) {
+    if (!ss->opt.enableNPN || !ss->nextProtoCallback || ss->firstHsDone) {
 	return 0;
     }
 
@@ -674,6 +727,74 @@ loser:
     return -1;
 }
 
+static PRInt32
+ssl3_ClientSendAppProtoXtn(sslSocket * ss, PRBool append, PRUint32 maxBytes)
+{
+    PRInt32 extension_length;
+    unsigned char *alpn_protos = NULL;
+
+    /* Renegotiations do not send this extension. */
+    if (!ss->opt.enableALPN || !ss->opt.nextProtoNego.data || ss->firstHsDone) {
+	return 0;
+    }
+
+    extension_length = 2 /* extension type */ + 2 /* extension length */ +
+		       2 /* protocol name list length */ +
+		       ss->opt.nextProtoNego.len;
+
+    if (append && maxBytes >= extension_length) {
+	/* NPN requires that the client's fallback protocol is first in the
+	 * list. However, ALPN sends protocols in preference order. So we
+	 * allocate a buffer and move the first protocol to the end of the
+	 * list. */
+	SECStatus rv;
+	const unsigned int len = ss->opt.nextProtoNego.len;
+
+	alpn_protos = PORT_Alloc(len);
+	if (alpn_protos == NULL) {
+	    return SECFailure;
+	}
+	if (len > 0) {
+	    /* Each protocol string is prefixed with a single byte length. */
+	    unsigned int i = ss->opt.nextProtoNego.data[0] + 1;
+	    if (i <= len) {
+		memcpy(alpn_protos, &ss->opt.nextProtoNego.data[i], len - i);
+		memcpy(alpn_protos + len - i, ss->opt.nextProtoNego.data, i);
+	    } else {
+		/* This seems to be invalid data so we'll send as-is. */
+		memcpy(alpn_protos, ss->opt.nextProtoNego.data, len);
+	    }
+	}
+
+	rv = ssl3_AppendHandshakeNumber(ss, ssl_app_layer_protocol_xtn, 2);
+	if (rv != SECSuccess) {
+	    goto loser;
+	}
+	rv = ssl3_AppendHandshakeNumber(ss, extension_length - 4, 2);
+	if (rv != SECSuccess) {
+	    goto loser;
+	}
+	rv = ssl3_AppendHandshakeVariable(ss, alpn_protos, len, 2);
+	PORT_Free(alpn_protos);
+	alpn_protos = NULL;
+	if (rv != SECSuccess) {
+	    goto loser;
+	}
+	ss->xtnData.advertised[ss->xtnData.numAdvertised++] =
+		ssl_app_layer_protocol_xtn;
+    } else if (maxBytes < extension_length) {
+	return 0;
+    }
+
+    return extension_length;
+
+loser:
+    if (alpn_protos) {
+	PORT_Free(alpn_protos);
+    }
+    return -1;
+}
+
 static SECStatus
 ssl3_ClientHandleStatusRequestXtn(sslSocket *ss, PRUint16 ex_type,
                                  SECItem *data)
diff --git a/lib/ssl/sslimpl.h b/lib/ssl/sslimpl.h
index 3750c2134..5f70d185b 100644
--- a/lib/ssl/sslimpl.h
+++ b/lib/ssl/sslimpl.h
@@ -324,6 +324,8 @@ typedef struct sslOptionsStr {
     unsigned int enableFalseStart       : 1;  /* 23 */
     unsigned int cbcRandomIV            : 1;  /* 24 */
     unsigned int enableOCSPStapling     : 1;  /* 25 */
+    unsigned int enableNPN              : 1;  /* 26 */
+    unsigned int enableALPN             : 1;  /* 27 */
 } sslOptions;
 
 typedef enum { sslHandshakingUndetermined = 0,
diff --git a/lib/ssl/sslsock.c b/lib/ssl/sslsock.c
index 60916776d..15344b877 100644
--- a/lib/ssl/sslsock.c
+++ b/lib/ssl/sslsock.c
@@ -78,7 +78,9 @@ static sslOptions ssl_defaults = {
     PR_FALSE,   /* requireSafeNegotiation */
     PR_FALSE,   /* enableFalseStart   */
     PR_TRUE,    /* cbcRandomIV        */
-    PR_FALSE    /* enableOCSPStapling */
+    PR_FALSE,   /* enableOCSPStapling */
+    PR_TRUE,    /* enableNPN          */
+    PR_FALSE    /* enableALPN         */
 };
 
 /*
@@ -764,6 +766,14 @@ SSL_OptionSet(PRFileDesc *fd, PRInt32 which, PRBool on)
        ss->opt.enableOCSPStapling = on;
        break;
 
+      case SSL_ENABLE_NPN:
+	ss->opt.enableNPN = on;
+	break;
+
+      case SSL_ENABLE_ALPN:
+	ss->opt.enableALPN = on;
+	break;
+
       default:
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
 	rv = SECFailure;
@@ -834,6 +844,8 @@ SSL_OptionGet(PRFileDesc *fd, PRInt32 which, PRBool *pOn)
     case SSL_ENABLE_FALSE_START:  on = ss->opt.enableFalseStart;   break;
     case SSL_CBC_RANDOM_IV:       on = ss->opt.cbcRandomIV;        break;
     case SSL_ENABLE_OCSP_STAPLING: on = ss->opt.enableOCSPStapling; break;
+    case SSL_ENABLE_NPN:          on = ss->opt.enableNPN;          break;
+    case SSL_ENABLE_ALPN:         on = ss->opt.enableALPN;         break;
 
     default:
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
@@ -895,6 +907,8 @@ SSL_OptionGetDefault(PRInt32 which, PRBool *pOn)
     case SSL_ENABLE_OCSP_STAPLING:
        on = ssl_defaults.enableOCSPStapling;
        break;
+    case SSL_ENABLE_NPN:          on = ssl_defaults.enableNPN;          break;
+    case SSL_ENABLE_ALPN:         on = ssl_defaults.enableALPN;         break;
 
     default:
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
@@ -1062,6 +1076,14 @@ SSL_OptionSetDefault(PRInt32 which, PRBool on)
        ssl_defaults.enableOCSPStapling = on;
        break;
 
+      case SSL_ENABLE_NPN:
+	ssl_defaults.enableNPN = on;
+	break;
+
+      case SSL_ENABLE_ALPN:
+	ssl_defaults.enableALPN = on;
+	break;
+
       default:
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
 	return SECFailure;
diff --git a/lib/ssl/sslt.h b/lib/ssl/sslt.h
index 350c1bbd7..fb25c6d72 100644
--- a/lib/ssl/sslt.h
+++ b/lib/ssl/sslt.h
@@ -187,12 +187,13 @@ typedef enum {
 #endif
     ssl_signature_algorithms_xtn     = 13,
     ssl_use_srtp_xtn                 = 14,
+    ssl_app_layer_protocol_xtn       = 16,
     ssl_session_ticket_xtn           = 35,
     ssl_next_proto_nego_xtn          = 13172,
     ssl_padding_xtn                  = 35655,
     ssl_renegotiation_info_xtn       = 0xff01	/* experimental number */
 } SSLExtensionType;
 
-#define SSL_MAX_EXTENSIONS             9 /* doesn't include ssl_padding_xtn. */
+#define SSL_MAX_EXTENSIONS             10 /* doesn't include ssl_padding_xtn. */
 
 #endif /* __sslt_h_ */