Support a user-provided string for the TLS ALPN extension.

webrtc/rtc_base/openssladapter_unittest.cc

+/*
+ *  Copyright 2017 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include "webrtc/rtc_base/gunit.h"
+#include "webrtc/rtc_base/openssladapter.h"
+
+namespace rtc {
+
+TEST(OpenSSLAdapterTest, TestTransformAlpnProtocols) {
+  EXPECT_EQ("", TransformAlpnProtocols(std::vector<std::string>()));
+
+  // Protocols larger than 255 characters (whose size can't be fit in a byte),
+  // can't be converted, and an empty string will be returned.
+  std::string large_protocol(256, 'a');
+  EXPECT_EQ("", TransformAlpnProtocols(
+      std::vector<std::string>{large_protocol}));
+
+  // One protocol test.
+  std::vector<std::string> alpn_protos{"h2"};
+  std::stringstream expected_response;
+  expected_response << static_cast<char>(2) << "h2";
+  EXPECT_EQ(expected_response.str(), TransformAlpnProtocols(alpn_protos));
+
+  // Standard protocols test (h2,http/1.1).
+  alpn_protos.push_back("http/1.1");
+  expected_response << static_cast<char>(8) << "http/1.1";
+  EXPECT_EQ(expected_response.str(), TransformAlpnProtocols(alpn_protos));
+}
+
+}  // namespace rtc
+