Tests for socks4/4a implementation.

Refactoring of void BuildHandshakeWriteBuffer() to const std::string BuildHandshakeWriteBuffer() const,
and removing private members handshake_buf_len_ and buffer_len_ (since buffer_ is now std::string, buffer_.size()) is more than sufficient.

TEST=unittests
BUG=none

Review URL: http://codereview.chromium.org/139009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@19354 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 433 insertions, 145 deletions

diff --git a/net/socket/socket_test_util.cc b/net/socket/socket_test_util.cc
index 8e0cb46..fc5ddf3 100644
--- a/net/socket/socket_test_util.cc
+++ b/net/socket/socket_test_util.cc
@@ -7,95 +7,11 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/message_loop.h"
-#include "net/base/io_buffer.h"
 #include "net/base/ssl_info.h"
 #include "net/socket/socket.h"
-#include "net/socket/ssl_client_socket.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace {
-
-class MockClientSocket : public net::SSLClientSocket {
- public:
-  MockClientSocket();
-
-  // ClientSocket methods:
-  virtual int Connect(net::CompletionCallback* callback) = 0;
-
-  // SSLClientSocket methods:
-  virtual void GetSSLInfo(net::SSLInfo* ssl_info);
-  virtual void GetSSLCertRequestInfo(
-      net::SSLCertRequestInfo* cert_request_info);
-  virtual void Disconnect();
-  virtual bool IsConnected() const;
-  virtual bool IsConnectedAndIdle() const;
-
-  // Socket methods:
-  virtual int Read(net::IOBuffer* buf, int buf_len,
-                   net::CompletionCallback* callback) = 0;
-  virtual int Write(net::IOBuffer* buf, int buf_len,
-                    net::CompletionCallback* callback) = 0;
-
-#if defined(OS_LINUX)
-  virtual int GetPeerName(struct sockaddr *name, socklen_t *namelen);
-#endif
-
- protected:
-  void RunCallbackAsync(net::CompletionCallback* callback, int result);
-  void RunCallback(int result);
-
-  ScopedRunnableMethodFactory<MockClientSocket> method_factory_;
-  net::CompletionCallback* callback_;
-  bool connected_;
-};
-
-class MockTCPClientSocket : public MockClientSocket {
- public:
-  MockTCPClientSocket(const net::AddressList& addresses,
-                      net::MockSocket* socket);
-
-  // ClientSocket methods:
-  virtual int Connect(net::CompletionCallback* callback);
-
-  // Socket methods:
-  virtual int Read(net::IOBuffer* buf, int buf_len,
-                   net::CompletionCallback* callback);
-  virtual int Write(net::IOBuffer* buf, int buf_len,
-                    net::CompletionCallback* callback);
-
- private:
-  net::MockSocket* data_;
-  int read_offset_;
-  net::MockRead read_data_;
-  bool need_read_data_;
-};
-
-class MockSSLClientSocket : public MockClientSocket {
- public:
-  MockSSLClientSocket(
-      net::ClientSocket* transport_socket,
-      const std::string& hostname,
-      const net::SSLConfig& ssl_config,
-      net::MockSSLSocket* socket);
-  ~MockSSLClientSocket();
-
-  virtual void GetSSLInfo(net::SSLInfo* ssl_info);
-
-  virtual int Connect(net::CompletionCallback* callback);
-  virtual void Disconnect();
-
-  // Socket methods:
-  virtual int Read(net::IOBuffer* buf, int buf_len,
-                   net::CompletionCallback* callback);
-  virtual int Write(net::IOBuffer* buf, int buf_len,
-                    net::CompletionCallback* callback);
-
- private:
-  class ConnectCallback;
-
-  scoped_ptr<ClientSocket> transport_;
-  net::MockSSLSocket* data_;
-};
+namespace net {
 
 MockClientSocket::MockClientSocket()
     : ALLOW_THIS_IN_INITIALIZER_LIST(method_factory_(this)),
@@ -301,10 +217,6 @@ int MockSSLClientSocket::Write(net::IOBuffer* buf, int buf_len,
   return transport_->Write(buf, buf_len, callback);
 }
 
-}  // namespace
-
-namespace net {
-
 MockRead StaticMockSocket::GetNextRead() {
   return reads_[read_index_++];
 }
diff --git a/net/socket/socket_test_util.h b/net/socket/socket_test_util.h
index bd7c437..f710820 100644
--- a/net/socket/socket_test_util.h
+++ b/net/socket/socket_test_util.h
@@ -10,10 +10,13 @@
 
 #include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/scoped_ptr.h"
 #include "net/base/address_list.h"
+#include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "net/base/ssl_config_service.h"
 #include "net/socket/client_socket_factory.h"
+#include "net/socket/ssl_client_socket.h"
 
 namespace net {
 
@@ -200,6 +203,88 @@ class MockClientSocketFactory : public ClientSocketFactory {
   MockSocketArray<MockSSLSocket> mock_ssl_sockets_;
 };
 
+class MockClientSocket : public net::SSLClientSocket {
+ public:
+  MockClientSocket();
+
+  // ClientSocket methods:
+  virtual int Connect(net::CompletionCallback* callback) = 0;
+
+  // SSLClientSocket methods:
+  virtual void GetSSLInfo(net::SSLInfo* ssl_info);
+  virtual void GetSSLCertRequestInfo(
+      net::SSLCertRequestInfo* cert_request_info);
+  virtual void Disconnect();
+  virtual bool IsConnected() const;
+  virtual bool IsConnectedAndIdle() const;
+
+  // Socket methods:
+  virtual int Read(net::IOBuffer* buf, int buf_len,
+                   net::CompletionCallback* callback) = 0;
+  virtual int Write(net::IOBuffer* buf, int buf_len,
+                    net::CompletionCallback* callback) = 0;
+
+#if defined(OS_LINUX)
+  virtual int GetPeerName(struct sockaddr *name, socklen_t *namelen);
+#endif
+
+ protected:
+  void RunCallbackAsync(net::CompletionCallback* callback, int result);
+  void RunCallback(int result);
+
+  ScopedRunnableMethodFactory<MockClientSocket> method_factory_;
+  net::CompletionCallback* callback_;
+  bool connected_;
+};
+
+class MockTCPClientSocket : public MockClientSocket {
+ public:
+  MockTCPClientSocket(const net::AddressList& addresses,
+                      net::MockSocket* socket);
+
+  // ClientSocket methods:
+  virtual int Connect(net::CompletionCallback* callback);
+
+  // Socket methods:
+  virtual int Read(net::IOBuffer* buf, int buf_len,
+                   net::CompletionCallback* callback);
+  virtual int Write(net::IOBuffer* buf, int buf_len,
+                    net::CompletionCallback* callback);
+
+ private:
+  net::MockSocket* data_;
+  int read_offset_;
+  net::MockRead read_data_;
+  bool need_read_data_;
+};
+
+class MockSSLClientSocket : public MockClientSocket {
+ public:
+  MockSSLClientSocket(
+      net::ClientSocket* transport_socket,
+      const std::string& hostname,
+      const net::SSLConfig& ssl_config,
+      net::MockSSLSocket* socket);
+  ~MockSSLClientSocket();
+
+  virtual void GetSSLInfo(net::SSLInfo* ssl_info);
+
+  virtual int Connect(net::CompletionCallback* callback);
+  virtual void Disconnect();
+
+  // Socket methods:
+  virtual int Read(net::IOBuffer* buf, int buf_len,
+                   net::CompletionCallback* callback);
+  virtual int Write(net::IOBuffer* buf, int buf_len,
+                    net::CompletionCallback* callback);
+
+ private:
+  class ConnectCallback;
+
+  scoped_ptr<ClientSocket> transport_;
+  net::MockSSLSocket* data_;
+};
+
 }  // namespace net
 
 #endif  // NET_SOCKET_SOCKET_TEST_UTIL_H_
diff --git a/net/socket/socks_client_socket.cc b/net/socket/socks_client_socket.cc
index 1bcf80c..0ccaeb6 100644
--- a/net/socket/socks_client_socket.cc
+++ b/net/socket/socks_client_socket.cc
@@ -72,9 +72,6 @@ SOCKSClientSocket::SOCKSClientSocket(ClientSocket* transport_socket,
       next_state_(STATE_NONE),
       socks_version_(kSOCKS4Unresolved),
       user_callback_(NULL),
-      handshake_buf_len_(0),
-      buffer_(NULL),
-      buffer_len_(0),
       completed_handshake_(false),
       bytes_sent_(0),
       bytes_received_(0),
@@ -233,65 +230,60 @@ int SOCKSClientSocket::DoResolveHostComplete(int result) {
 // Builds the buffer that is to be sent to the server.
 // We check whether the SOCKS proxy is 4 or 4A.
 // In case it is 4A, the record size increases by size of the hostname.
-void SOCKSClientSocket::BuildHandshakeWriteBuffer() {
+const std::string SOCKSClientSocket::BuildHandshakeWriteBuffer() const {
   DCHECK_NE(kSOCKS4Unresolved, socks_version_);
 
-  int record_size = kWriteHeaderSize + arraysize(kEmptyUserId);
-  if (socks_version_ == kSOCKS4a) {
-    record_size += host_request_info_.hostname().size() + 1;
-  }
-
-  buffer_len_ = record_size;
-  buffer_.reset(new char[buffer_len_]);
-
-  SOCKS4ServerRequest* request =
-      reinterpret_cast<SOCKS4ServerRequest*>(buffer_.get());
-
-  request->version = kSOCKSVersion4;
-  request->command = kSOCKSStreamRequest;
-  request->nw_port = htons(host_request_info_.port());
+  SOCKS4ServerRequest request;
+  request.version = kSOCKSVersion4;
+  request.command = kSOCKSStreamRequest;
+  request.nw_port = htons(host_request_info_.port());
 
   if (socks_version_ == kSOCKS4) {
     const struct addrinfo* ai = addresses_.head();
     DCHECK(ai);
     // If the sockaddr is IPv6, we have already marked the version to socks4a
     // and so this step does not get hit.
-    struct sockaddr_in *ipv4_host =
+    struct sockaddr_in* ipv4_host =
         reinterpret_cast<struct sockaddr_in*>(ai->ai_addr);
-    memcpy(&request->ip, &(ipv4_host->sin_addr), sizeof(ipv4_host->sin_addr));
+    memcpy(&request.ip, &(ipv4_host->sin_addr), sizeof(ipv4_host->sin_addr));
 
     DLOG(INFO) << "Resolved Host is : " << NetAddressToString(ai);
   } else if (socks_version_ == kSOCKS4a) {
     // invalid IP of the form 0.0.0.127
-    memcpy(&request->ip, kInvalidIp, arraysize(kInvalidIp));
+    memcpy(&request.ip, kInvalidIp, arraysize(kInvalidIp));
   } else {
     NOTREACHED();
   }
 
-  memcpy(&buffer_[kWriteHeaderSize], kEmptyUserId, arraysize(kEmptyUserId));
+  std::string handshake_data(reinterpret_cast<char*>(&request),
+                             sizeof(request));
+  handshake_data.append(kEmptyUserId, arraysize(kEmptyUserId));
 
+  // In case we are passing the domain also, pass the hostname
+  // terminated with a null character.
   if (socks_version_ == kSOCKS4a) {
-    memcpy(&buffer_[kWriteHeaderSize + arraysize(kEmptyUserId)],
-           host_request_info_.hostname().c_str(),
-           host_request_info_.hostname().size() + 1);
+    handshake_data.append(host_request_info_.hostname());
+    handshake_data.push_back('\0');
   }
+
+  return handshake_data;
 }
 
 // Writes the SOCKS handshake data to the underlying socket connection.
 int SOCKSClientSocket::DoHandshakeWrite() {
   next_state_ = STATE_HANDSHAKE_WRITE_COMPLETE;
 
-  if (!buffer_.get()) {
-    BuildHandshakeWriteBuffer();
+  if (buffer_.empty()) {
+    buffer_ = BuildHandshakeWriteBuffer();
     bytes_sent_ = 0;
   }
 
-  handshake_buf_len_ = buffer_len_ - bytes_sent_;
-  DCHECK_GT(handshake_buf_len_, 0);
-  handshake_buf_ = new IOBuffer(handshake_buf_len_);
-  memcpy(handshake_buf_.get()->data(), &buffer_[bytes_sent_],
-         handshake_buf_len_);
-  return transport_->Write(handshake_buf_, handshake_buf_len_, &io_callback_);
+  int handshake_buf_len = buffer_.size() - bytes_sent_;
+  DCHECK_GT(handshake_buf_len, 0);
+  handshake_buf_ = new IOBuffer(handshake_buf_len);
+  memcpy(handshake_buf_->data(), &buffer_[bytes_sent_],
+         handshake_buf_len);
+  return transport_->Write(handshake_buf_, handshake_buf_len, &io_callback_);
 }
 
 int SOCKSClientSocket::DoHandshakeWriteComplete(int result) {
@@ -300,11 +292,14 @@ int SOCKSClientSocket::DoHandshakeWriteComplete(int result) {
   if (result < 0)
     return result;
 
+  // We ignore the case when result is 0, since the underlying Write
+  // may return spurious writes while waiting on the socket.
+
   bytes_sent_ += result;
-  if (bytes_sent_ == buffer_len_) {
+  if (bytes_sent_ == buffer_.size()) {
     next_state_ = STATE_HANDSHAKE_READ;
-    buffer_.reset(NULL);
-  } else if (bytes_sent_ < buffer_len_) {
+    buffer_.clear();
+  } else if (bytes_sent_ < buffer_.size()) {
     next_state_ = STATE_HANDSHAKE_WRITE;
   } else {
     return ERR_UNEXPECTED;
@@ -318,15 +313,13 @@ int SOCKSClientSocket::DoHandshakeRead() {
 
   next_state_ = STATE_HANDSHAKE_READ_COMPLETE;
 
-  if (!buffer_.get()) {
-    buffer_.reset(new char[kReadHeaderSize]);
-    buffer_len_ = kReadHeaderSize;
+  if (buffer_.empty()) {
     bytes_received_ = 0;
   }
 
-  handshake_buf_len_ = buffer_len_ - bytes_received_;
-  handshake_buf_ = new IOBuffer(handshake_buf_len_);
-  return transport_->Read(handshake_buf_, handshake_buf_len_, &io_callback_);
+  int handshake_buf_len = kReadHeaderSize - bytes_received_;
+  handshake_buf_ = new IOBuffer(handshake_buf_len);
+  return transport_->Read(handshake_buf_, handshake_buf_len, &io_callback_);
 }
 
 int SOCKSClientSocket::DoHandshakeReadComplete(int result) {
@@ -334,18 +327,23 @@ int SOCKSClientSocket::DoHandshakeReadComplete(int result) {
 
   if (result < 0)
     return result;
-  if (bytes_received_ + result > buffer_len_)
+
+  // The underlying socket closed unexpectedly.
+  if (result == 0)
+    return ERR_CONNECTION_CLOSED;
+
+  if (bytes_received_ + result > kReadHeaderSize)
     return ERR_INVALID_RESPONSE;
 
-  memcpy(buffer_.get() + bytes_received_, handshake_buf_->data(), result);
+  buffer_.append(handshake_buf_->data(), result);
   bytes_received_ += result;
-  if (bytes_received_ < buffer_len_) {
+  if (bytes_received_ < kReadHeaderSize) {
     next_state_ = STATE_HANDSHAKE_READ;
     return OK;
   }
 
-  SOCKS4ServerResponse* response =
-      reinterpret_cast<SOCKS4ServerResponse*>(buffer_.get());
+  const SOCKS4ServerResponse* response =
+      reinterpret_cast<const SOCKS4ServerResponse*>(buffer_.data());
 
   if (response->reserved_null != 0x00) {
     LOG(ERROR) << "Unknown response from SOCKS server.";
diff --git a/net/socket/socks_client_socket.h b/net/socket/socks_client_socket.h
index 03925ba..295000a 100644
--- a/net/socket/socks_client_socket.h
+++ b/net/socket/socks_client_socket.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef NET_BASE_SOCKS_CLIENT_SOCKET_H_
-#define NET_BASE_SOCKS_CLIENT_SOCKET_H_
+#ifndef NET_SOCKET_SOCKS_CLIENT_SOCKET_H_
+#define NET_SOCKET_SOCKS_CLIENT_SOCKET_H_
 
 #include <string>
 
@@ -54,6 +54,10 @@ class SOCKSClientSocket : public ClientSocket {
 #endif
 
  private:
+  FRIEND_TEST(SOCKSClientSocketTest, CompleteHandshake);
+  FRIEND_TEST(SOCKSClientSocketTest, SOCKS4AFailedDNS);
+  FRIEND_TEST(SOCKSClientSocketTest, SOCKS4AIfDomainInIPv6);
+
   enum State {
     STATE_RESOLVE_HOST,
     STATE_RESOLVE_HOST_COMPLETE,
@@ -85,7 +89,7 @@ class SOCKSClientSocket : public ClientSocket {
   int DoHandshakeWrite();
   int DoHandshakeWriteComplete(int result);
 
-  void BuildHandshakeWriteBuffer();
+  const std::string BuildHandshakeWriteBuffer() const;
 
   CompletionCallbackImpl<SOCKSClientSocket> io_callback_;
 
@@ -102,20 +106,18 @@ class SOCKSClientSocket : public ClientSocket {
   // SOCKS handshake data. The length contains the expected size to
   // read or write.
   scoped_refptr<IOBuffer> handshake_buf_;
-  int handshake_buf_len_;
 
   // While writing, this buffer stores the complete write handshake data.
   // While reading, it stores the handshake information received so far.
-  scoped_array<char> buffer_;
-  int buffer_len_;
+  std::string buffer_;
 
   // This becomes true when the SOCKS handshake has completed and the
   // overlying connection is free to communicate.
   bool completed_handshake_;
 
   // These contain the bytes sent / received by the SOCKS handshake.
-  int bytes_sent_;
-  int bytes_received_;
+  size_t bytes_sent_;
+  size_t bytes_received_;
 
   // Used to resolve the hostname to which the SOCKS proxy will connect.
   SingleRequestHostResolver resolver_;
@@ -127,5 +129,5 @@ class SOCKSClientSocket : public ClientSocket {
 
 }  // namespace net
 
-#endif  // NET_BASE_SOCKS_CLIENT_SOCKET_H_
+#endif  // NET_SOCKET_SOCKS_CLIENT_SOCKET_H_
 
diff --git a/net/socket/socks_client_socket_unittest.cc b/net/socket/socks_client_socket_unittest.cc
new file mode 100644
index 0000000..813a48e
--- /dev/null
+++ b/net/socket/socks_client_socket_unittest.cc
@@ -0,0 +1,291 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/socket/socks_client_socket.h"
+
+#include "net/base/address_list.h"
+#include "net/base/host_resolver_unittest.h"
+#include "net/base/listen_socket.h"
+#include "net/base/test_completion_callback.h"
+#include "net/base/winsock_init.h"
+#include "net/socket/client_socket_factory.h"
+#include "net/socket/tcp_client_socket.h"
+#include "net/socket/socket_test_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+//-----------------------------------------------------------------------------
+
+namespace net {
+
+const char kSOCKSOkRequest[] = { 0x04, 0x01, 0x00, 0x50, 127, 0, 0, 1, 0 };
+const char kSOCKS4aInitialRequest[] =
+    { 0x04, 0x01, 0x00, 0x50, 0, 0, 0, 127, 0 };
+const char kSOCKSOkReply[] = { 0x00, 0x5A, 0x00, 0x00, 0, 0, 0, 0 };
+
+class SOCKSClientSocketTest : public PlatformTest {
+ public:
+  SOCKSClientSocketTest();
+  // Create a SOCKSClientSocket on top of a MockSocket.
+  SOCKSClientSocket* BuildMockSocket(MockRead reads[], MockWrite writes[],
+                                     const std::string& hostname, int port);
+  virtual void SetUp();
+
+ protected:
+  scoped_ptr<SOCKSClientSocket> user_sock_;
+  AddressList address_list_;
+  ClientSocket* tcp_sock_;
+  ScopedHostMapper host_mapper_;
+  TestCompletionCallback callback_;
+  scoped_refptr<RuleBasedHostMapper> mapper_;
+  HostResolver host_resolver_;
+  scoped_ptr<MockSocket> mock_socket_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SOCKSClientSocketTest);
+};
+
+SOCKSClientSocketTest::SOCKSClientSocketTest()
+  : host_resolver_(0, 0) {
+}
+
+// Set up platform before every test case
+void SOCKSClientSocketTest::SetUp() {
+  PlatformTest::SetUp();
+
+  // Resolve the "localhost" AddressList used by the tcp_connection to connect.
+  HostResolver resolver;
+  HostResolver::RequestInfo info("localhost", 1080);
+  int rv = resolver.Resolve(info, &address_list_, NULL, NULL);
+  ASSERT_EQ(OK, rv);
+
+  // Create a new host mapping for the duration of this test case only.
+  mapper_ = new RuleBasedHostMapper();
+  host_mapper_.Init(mapper_);
+  mapper_->AddRule("www.google.com", "127.0.0.1");
+}
+
+SOCKSClientSocket* SOCKSClientSocketTest::BuildMockSocket(
+    MockRead reads[],
+    MockWrite writes[],
+    const std::string& hostname,
+    int port) {
+
+  TestCompletionCallback callback;
+  mock_socket_.reset(new StaticMockSocket(reads, writes));
+  tcp_sock_ = new MockTCPClientSocket(address_list_, mock_socket_.get());
+
+  int rv = tcp_sock_->Connect(&callback);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback.WaitForResult();
+  EXPECT_EQ(OK, rv);
+  EXPECT_TRUE(tcp_sock_->IsConnected());
+
+  return new SOCKSClientSocket(tcp_sock_,
+      HostResolver::RequestInfo(hostname, port),
+      &host_resolver_);
+}
+
+// Tests a complete handshake and the disconnection.
+TEST_F(SOCKSClientSocketTest, CompleteHandshake) {
+  const std::string payload_write = "random data";
+  const std::string payload_read = "moar random data";
+
+  MockWrite data_writes[] = {
+      MockWrite(true, kSOCKSOkRequest, arraysize(kSOCKSOkRequest)),
+      MockWrite(true, payload_write.data(), payload_write.size()) };
+  MockRead data_reads[] = {
+      MockRead(true, kSOCKSOkReply, arraysize(kSOCKSOkReply)),
+      MockRead(true, payload_read.data(), payload_read.size()) };
+
+  user_sock_.reset(BuildMockSocket(data_reads, data_writes, "localhost", 80));
+
+  // At this state the TCP connection is completed but not the SOCKS handshake.
+  EXPECT_TRUE(tcp_sock_->IsConnected());
+  EXPECT_FALSE(user_sock_->IsConnected());
+
+  int rv = user_sock_->Connect(&callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  EXPECT_FALSE(user_sock_->IsConnected());
+  rv = callback_.WaitForResult();
+
+  EXPECT_EQ(OK, rv);
+  EXPECT_TRUE(user_sock_->IsConnected());
+  EXPECT_EQ(SOCKSClientSocket::kSOCKS4, user_sock_->socks_version_);
+
+  scoped_refptr<IOBuffer> buffer = new IOBuffer(payload_write.size());
+  memcpy(buffer->data(), payload_write.data(), payload_write.size());
+  rv = user_sock_->Write(buffer, payload_write.size(), &callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback_.WaitForResult();
+  EXPECT_EQ(payload_write.size(), rv);
+
+  buffer = new IOBuffer(payload_read.size());
+  rv = user_sock_->Read(buffer, payload_read.size(), &callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback_.WaitForResult();
+  EXPECT_EQ(payload_read.size(), rv);
+  EXPECT_EQ(payload_read, std::string(buffer->data(), payload_read.size()));
+
+  user_sock_->Disconnect();
+  EXPECT_FALSE(tcp_sock_->IsConnected());
+  EXPECT_FALSE(user_sock_->IsConnected());
+}
+
+// List of responses from the socks server and the errors they should
+// throw up are tested here.
+TEST_F(SOCKSClientSocketTest, HandshakeFailures) {
+  const struct {
+    const char fail_reply[8];
+    Error fail_code;
+  } tests[] = {
+    // Failure of the server response code
+    {
+      { 0x01, 0x5A, 0x00, 0x00, 0, 0, 0, 0 },
+      ERR_INVALID_RESPONSE,
+    },
+    // Failure of the null byte
+    {
+      { 0x00, 0x5B, 0x00, 0x00, 0, 0, 0, 0 },
+      ERR_FAILED,
+    },
+  };
+
+  //---------------------------------------
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(tests); ++i) {
+    MockWrite data_writes[] = {
+        MockWrite(false, kSOCKSOkRequest, arraysize(kSOCKSOkRequest)) };
+    MockRead data_reads[] = {
+        MockRead(false, tests[i].fail_reply, arraysize(tests[i].fail_reply)) };
+
+    user_sock_.reset(BuildMockSocket(data_reads, data_writes, "localhost", 80));
+
+    int rv = user_sock_->Connect(&callback_);
+    EXPECT_EQ(ERR_IO_PENDING, rv);
+    rv = callback_.WaitForResult();
+    EXPECT_EQ(tests[i].fail_code, rv);
+    EXPECT_FALSE(user_sock_->IsConnected());
+    EXPECT_TRUE(tcp_sock_->IsConnected());
+  }
+}
+
+// Tests scenario when the server sends the handshake response in
+// more than one packet.
+TEST_F(SOCKSClientSocketTest, PartialServerReads) {
+  const char kSOCKSPartialReply1[] = { 0x00 };
+  const char kSOCKSPartialReply2[] = { 0x5A, 0x00, 0x00, 0, 0, 0, 0 };
+
+  MockWrite data_writes[] = {
+      MockWrite(true, kSOCKSOkRequest, arraysize(kSOCKSOkRequest)) };
+  MockRead data_reads[] = {
+      MockRead(true, kSOCKSPartialReply1, arraysize(kSOCKSPartialReply1)),
+      MockRead(true, kSOCKSPartialReply2, arraysize(kSOCKSPartialReply2)) };
+
+  user_sock_.reset(BuildMockSocket(data_reads, data_writes, "localhost", 80));
+
+  int rv = user_sock_->Connect(&callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback_.WaitForResult();
+  EXPECT_EQ(OK, rv);
+  EXPECT_TRUE(user_sock_->IsConnected());
+}
+
+// Tests scenario when the client sends the handshake request in
+// more than one packet.
+TEST_F(SOCKSClientSocketTest, PartialClientWrites) {
+  const char kSOCKSPartialRequest1[] = { 0x04, 0x01 };
+  const char kSOCKSPartialRequest2[] = { 0x00, 0x50, 127, 0, 0, 1, 0 };
+
+  MockWrite data_writes[] = {
+      MockWrite(true, arraysize(kSOCKSPartialRequest1)),
+      // simulate some empty writes
+      MockWrite(true, 0),
+      MockWrite(true, 0),
+      MockWrite(true, kSOCKSPartialRequest2,
+                arraysize(kSOCKSPartialRequest2)) };
+  MockRead data_reads[] = {
+      MockRead(true, kSOCKSOkReply, arraysize(kSOCKSOkReply)) };
+
+  user_sock_.reset(BuildMockSocket(data_reads, data_writes, "localhost", 80));
+
+  int rv = user_sock_->Connect(&callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback_.WaitForResult();
+  EXPECT_EQ(OK, rv);
+  EXPECT_TRUE(user_sock_->IsConnected());
+}
+
+// Tests the case when the server sends a smaller sized handshake data
+// and closes the connection.
+TEST_F(SOCKSClientSocketTest, FailedSocketRead) {
+  MockWrite data_writes[] = {
+      MockWrite(true, kSOCKSOkRequest, arraysize(kSOCKSOkRequest)) };
+  MockRead data_reads[] = {
+      MockRead(true, kSOCKSOkReply, arraysize(kSOCKSOkReply) - 2),
+      // close connection unexpectedly
+      MockRead(false, 0) };
+
+  user_sock_.reset(BuildMockSocket(data_reads, data_writes, "localhost", 80));
+
+  int rv = user_sock_->Connect(&callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback_.WaitForResult();
+  EXPECT_EQ(ERR_CONNECTION_CLOSED, rv);
+  EXPECT_FALSE(user_sock_->IsConnected());
+}
+
+// Tries to connect to an unknown DNS and on failure should revert to SOCKS4A.
+TEST_F(SOCKSClientSocketTest, SOCKS4AFailedDNS) {
+  const char hostname[] = "unresolved.ipv4.address";
+
+  mapper_->AddSimulatedFailure(hostname);
+
+  std::string request(kSOCKS4aInitialRequest,
+                      arraysize(kSOCKS4aInitialRequest));
+  request.append(hostname, arraysize(hostname));
+
+  MockWrite data_writes[] = {
+      MockWrite(false, request.data(), request.size()) };
+  MockRead data_reads[] = {
+      MockRead(false, kSOCKSOkReply, arraysize(kSOCKSOkReply)) };
+
+  user_sock_.reset(BuildMockSocket(data_reads, data_writes, hostname, 80));
+
+  int rv = user_sock_->Connect(&callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback_.WaitForResult();
+  EXPECT_EQ(OK, rv);
+  EXPECT_TRUE(user_sock_->IsConnected());
+  EXPECT_EQ(SOCKSClientSocket::kSOCKS4a, user_sock_->socks_version_);
+}
+
+// Tries to connect to a domain that resolves to IPv6.
+// Should revert to SOCKS4a.
+TEST_F(SOCKSClientSocketTest, SOCKS4AIfDomainInIPv6) {
+  const char hostname[] = "an.ipv6.address";
+
+  mapper_->AddRule(hostname, "2001:db8:8714:3a90::12");
+
+  std::string request(kSOCKS4aInitialRequest,
+                      arraysize(kSOCKS4aInitialRequest));
+  request.append(hostname, arraysize(hostname));
+
+  MockWrite data_writes[] = {
+      MockWrite(false, request.data(), request.size()) };
+  MockRead data_reads[] = {
+      MockRead(false, kSOCKSOkReply, arraysize(kSOCKSOkReply)) };
+
+  user_sock_.reset(BuildMockSocket(data_reads, data_writes, hostname, 80));
+
+  int rv = user_sock_->Connect(&callback_);
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  rv = callback_.WaitForResult();
+  EXPECT_EQ(OK, rv);
+  EXPECT_TRUE(user_sock_->IsConnected());
+  EXPECT_EQ(SOCKSClientSocket::kSOCKS4a, user_sock_->socks_version_);
+}
+
+}  // namespace net
+