fastboot: add TCP protocol.

This CL implements a TCP protocol for use with fastboot. Protocol
description is given in fastboot_protocol.txt, some examples of
expected behavior can also be found in tcp_test.cpp.

Usage is:
  fastboot -s tcp:<hostname>[:port] <command>

Bug: http://b/26558551
Change-Id: If53a514a534489c617db32c4fea8819949121282
diff --git a/fastboot/tcp_test.cpp b/fastboot/tcp_test.cpp
new file mode 100644
index 0000000..7d80d76
--- /dev/null
+++ b/fastboot/tcp_test.cpp
@@ -0,0 +1,217 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "tcp.h"
+
+#include <gtest/gtest.h>
+
+#include "socket_mock.h"
+
+TEST(TcpConnectTest, TestSuccess) {
+    std::unique_ptr<SocketMock> mock(new SocketMock);
+    mock->ExpectSend("FB01");
+    mock->AddReceive("FB01");
+
+    std::string error;
+    EXPECT_NE(nullptr, tcp::internal::Connect(std::move(mock), &error));
+    EXPECT_EQ("", error);
+}
+
+TEST(TcpConnectTest, TestSendFailure) {
+    std::unique_ptr<SocketMock> mock(new SocketMock);
+    mock->ExpectSendFailure("FB01");
+
+    std::string error;
+    EXPECT_EQ(nullptr, tcp::internal::Connect(std::move(mock), &error));
+    EXPECT_NE(std::string::npos, error.find("Failed to send initialization message"));
+}
+
+TEST(TcpConnectTest, TestNoResponseFailure) {
+    std::unique_ptr<SocketMock> mock(new SocketMock);
+    mock->ExpectSend("FB01");
+    mock->AddReceiveFailure();
+
+    std::string error;
+    EXPECT_EQ(nullptr, tcp::internal::Connect(std::move(mock), &error));
+    EXPECT_NE(std::string::npos, error.find("No initialization message received"));
+}
+
+TEST(TcpConnectTest, TestBadResponseFailure) {
+    std::unique_ptr<SocketMock> mock(new SocketMock);
+    mock->ExpectSend("FB01");
+    mock->AddReceive("XX01");
+
+    std::string error;
+    EXPECT_EQ(nullptr, tcp::internal::Connect(std::move(mock), &error));
+    EXPECT_NE(std::string::npos, error.find("Unrecognized initialization message"));
+}
+
+TEST(TcpConnectTest, TestUnknownVersionFailure) {
+    std::unique_ptr<SocketMock> mock(new SocketMock);
+    mock->ExpectSend("FB01");
+    mock->AddReceive("FB02");
+
+    std::string error;
+    EXPECT_EQ(nullptr, tcp::internal::Connect(std::move(mock), &error));
+    EXPECT_EQ("Unknown TCP protocol version 02 (host version 01)", error);
+}
+
+// Fixture to configure a SocketMock for a successful TCP connection.
+class TcpTest : public ::testing::Test {
+  protected:
+    void SetUp() override {
+        mock_ = new SocketMock;
+        mock_->ExpectSend("FB01");
+        mock_->AddReceive("FB01");
+
+        std::string error;
+        transport_ = tcp::internal::Connect(std::unique_ptr<Socket>(mock_), &error);
+        ASSERT_NE(nullptr, transport_);
+        ASSERT_EQ("", error);
+    };
+
+    // Writes |message| to |transport_|, returns true on success.
+    bool Write(const std::string& message) {
+        return transport_->Write(message.data(), message.length()) ==
+               static_cast<ssize_t>(message.length());
+    }
+
+    // Reads from |transport_|, returns true if it matches |message|.
+    bool Read(const std::string& message) {
+        std::string buffer(message.length(), '\0');
+        return transport_->Read(&buffer[0], buffer.length()) ==
+                       static_cast<ssize_t>(message.length()) &&
+               buffer == message;
+    }
+
+    // Use a raw SocketMock* here because we pass ownership to the Transport object, but we still
+    // need access to configure mock expectations.
+    SocketMock* mock_ = nullptr;
+    std::unique_ptr<Transport> transport_;
+};
+
+TEST_F(TcpTest, TestWriteSuccess) {
+    mock_->ExpectSend(std::string{0, 0, 0, 0, 0, 0, 0, 3} + "foo");
+
+    EXPECT_TRUE(Write("foo"));
+}
+
+TEST_F(TcpTest, TestReadSuccess) {
+    mock_->AddReceive(std::string{0, 0, 0, 0, 0, 0, 0, 3});
+    mock_->AddReceive("foo");
+
+    EXPECT_TRUE(Read("foo"));
+}
+
+// Tests that fragmented TCP reads are handled properly.
+TEST_F(TcpTest, TestReadFragmentSuccess) {
+    mock_->AddReceive(std::string{0, 0, 0, 0});
+    mock_->AddReceive(std::string{0, 0, 0, 3});
+    mock_->AddReceive("f");
+    mock_->AddReceive("o");
+    mock_->AddReceive("o");
+
+    EXPECT_TRUE(Read("foo"));
+}
+
+TEST_F(TcpTest, TestLargeWriteSuccess) {
+    // 0x100000 = 1MiB.
+    std::string data(0x100000, '\0');
+    for (size_t i = 0; i < data.length(); ++i) {
+        data[i] = i;
+    }
+    mock_->ExpectSend(std::string{0, 0, 0, 0, 0, 0x10, 0, 0} + data);
+
+    EXPECT_TRUE(Write(data));
+}
+
+TEST_F(TcpTest, TestLargeReadSuccess) {
+    // 0x100000 = 1MiB.
+    std::string data(0x100000, '\0');
+    for (size_t i = 0; i < data.length(); ++i) {
+        data[i] = i;
+    }
+    mock_->AddReceive(std::string{0, 0, 0, 0, 0, 0x10, 0, 0});
+    mock_->AddReceive(data);
+
+    EXPECT_TRUE(Read(data));
+}
+
+// Tests a few sample fastboot protocol commands.
+TEST_F(TcpTest, TestFastbootProtocolSuccess) {
+    mock_->ExpectSend(std::string{0, 0, 0, 0, 0, 0, 0, 14} + "getvar:version");
+    mock_->AddReceive(std::string{0, 0, 0, 0, 0, 0, 0, 7});
+    mock_->AddReceive("OKAY0.4");
+
+    mock_->ExpectSend(std::string{0, 0, 0, 0, 0, 0, 0, 10} + "getvar:all");
+    mock_->AddReceive(std::string{0, 0, 0, 0, 0, 0, 0, 16});
+    mock_->AddReceive("INFOversion: 0.4");
+    mock_->AddReceive(std::string{0, 0, 0, 0, 0, 0, 0, 12});
+    mock_->AddReceive("INFOfoo: bar");
+    mock_->AddReceive(std::string{0, 0, 0, 0, 0, 0, 0, 4});
+    mock_->AddReceive("OKAY");
+
+    EXPECT_TRUE(Write("getvar:version"));
+    EXPECT_TRUE(Read("OKAY0.4"));
+
+    EXPECT_TRUE(Write("getvar:all"));
+    EXPECT_TRUE(Read("INFOversion: 0.4"));
+    EXPECT_TRUE(Read("INFOfoo: bar"));
+    EXPECT_TRUE(Read("OKAY"));
+}
+
+TEST_F(TcpTest, TestReadLengthFailure) {
+    mock_->AddReceiveFailure();
+
+    char buffer[16];
+    EXPECT_EQ(-1, transport_->Read(buffer, sizeof(buffer)));
+}
+
+TEST_F(TcpTest, TestReadDataFailure) {
+    mock_->AddReceive(std::string{0, 0, 0, 0, 0, 0, 0, 3});
+    mock_->AddReceiveFailure();
+
+    char buffer[16];
+    EXPECT_EQ(-1, transport_->Read(buffer, sizeof(buffer)));
+}
+
+TEST_F(TcpTest, TestWriteFailure) {
+    mock_->ExpectSendFailure(std::string{0, 0, 0, 0, 0, 0, 0, 3} + "foo");
+
+    EXPECT_EQ(-1, transport_->Write("foo", 3));
+}
+
+TEST_F(TcpTest, TestTransportClose) {
+    EXPECT_EQ(0, transport_->Close());
+
+    // After closing, Transport Read()/Write() should return -1 without actually attempting any
+    // network operations.
+    char buffer[16];
+    EXPECT_EQ(-1, transport_->Read(buffer, sizeof(buffer)));
+    EXPECT_EQ(-1, transport_->Write("foo", 3));
+}