// 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/socks5_client_socket.h"

#include "base/basictypes.h"
#include "build/build_config.h"
#if defined(OS_WIN)
#include <ws2tcpip.h>
#elif defined(OS_POSIX)
#include <netdb.h>
#endif
#include "base/compiler_specific.h"
#include "base/trace_event.h"
#include "net/base/io_buffer.h"
#include "net/base/net_util.h"

namespace net {

const unsigned int SOCKS5ClientSocket::kGreetReadHeaderSize = 2;
const unsigned int SOCKS5ClientSocket::kWriteHeaderSize = 10;
const unsigned int SOCKS5ClientSocket::kReadHeaderSize = 5;
const uint8 SOCKS5ClientSocket::kSOCKS5Version = 0x05;
const uint8 SOCKS5ClientSocket::kTunnelCommand = 0x01;
const uint8 SOCKS5ClientSocket::kNullByte = 0x00;

COMPILE_ASSERT(sizeof(struct in_addr) == 4, incorrect_system_size_of_IPv4);
COMPILE_ASSERT(sizeof(struct in6_addr) == 16, incorrect_system_size_of_IPv6);

SOCKS5ClientSocket::SOCKS5ClientSocket(ClientSocket* transport_socket,
    const HostResolver::RequestInfo& req_info,
    HostResolver* host_resolver)
    : ALLOW_THIS_IN_INITIALIZER_LIST(
          io_callback_(this, &SOCKS5ClientSocket::OnIOComplete)),
      transport_(transport_socket),
      next_state_(STATE_NONE),
      address_type_(kEndPointUnresolved),
      user_callback_(NULL),
      completed_handshake_(false),
      bytes_sent_(0),
      bytes_received_(0),
      read_header_size(kReadHeaderSize),
      host_resolver_(host_resolver),
      host_request_info_(req_info) {
}

SOCKS5ClientSocket::~SOCKS5ClientSocket() {
  Disconnect();
}

int SOCKS5ClientSocket::Connect(CompletionCallback* callback) {
  DCHECK(transport_.get());
  DCHECK(transport_->IsConnected());
  DCHECK_EQ(STATE_NONE, next_state_);
  DCHECK(!user_callback_);

  // If already connected, then just return OK.
  if (completed_handshake_)
    return OK;

  next_state_ = STATE_RESOLVE_HOST;

  int rv = DoLoop(OK);
  if (rv == ERR_IO_PENDING)
    user_callback_ = callback;
  return rv;
}

void SOCKS5ClientSocket::Disconnect() {
  completed_handshake_ = false;
  transport_->Disconnect();
}

bool SOCKS5ClientSocket::IsConnected() const {
  return completed_handshake_ && transport_->IsConnected();
}

bool SOCKS5ClientSocket::IsConnectedAndIdle() const {
  return completed_handshake_ && transport_->IsConnectedAndIdle();
}

// Read is called by the transport layer above to read. This can only be done
// if the SOCKS handshake is complete.
int SOCKS5ClientSocket::Read(IOBuffer* buf, int buf_len,
                            CompletionCallback* callback) {
  DCHECK(completed_handshake_);
  DCHECK_EQ(STATE_NONE, next_state_);
  DCHECK(!user_callback_);

  return transport_->Read(buf, buf_len, callback);
}

// Write is called by the transport layer. This can only be done if the
// SOCKS handshake is complete.
int SOCKS5ClientSocket::Write(IOBuffer* buf, int buf_len,
                             CompletionCallback* callback) {
  DCHECK(completed_handshake_);
  DCHECK_EQ(STATE_NONE, next_state_);
  DCHECK(!user_callback_);

  return transport_->Write(buf, buf_len, callback);
}

bool SOCKS5ClientSocket::SetReceiveBufferSize(int32 size) {
  return transport_->SetReceiveBufferSize(size);
}

bool SOCKS5ClientSocket::SetSendBufferSize(int32 size) {
  return transport_->SetSendBufferSize(size);
}

void SOCKS5ClientSocket::DoCallback(int result) {
  DCHECK_NE(ERR_IO_PENDING, result);
  DCHECK(user_callback_);

  // Since Run() may result in Read being called,
  // clear user_callback_ up front.
  CompletionCallback* c = user_callback_;
  user_callback_ = NULL;
  DLOG(INFO) << "Finished setting up SOCKSv5 handshake";
  c->Run(result);
}

void SOCKS5ClientSocket::OnIOComplete(int result) {
  DCHECK_NE(STATE_NONE, next_state_);
  int rv = DoLoop(result);
  if (rv != ERR_IO_PENDING)
    DoCallback(rv);
}

int SOCKS5ClientSocket::DoLoop(int last_io_result) {
  DCHECK_NE(next_state_, STATE_NONE);
  int rv = last_io_result;
  do {
    State state = next_state_;
    next_state_ = STATE_NONE;
    switch (state) {
      case STATE_RESOLVE_HOST:
        DCHECK_EQ(OK, rv);
        rv = DoResolveHost();
        break;
      case STATE_RESOLVE_HOST_COMPLETE:
        rv = DoResolveHostComplete(rv);
        break;
      case STATE_GREET_WRITE:
        DCHECK_EQ(OK, rv);
        rv = DoGreetWrite();
        break;
      case STATE_GREET_WRITE_COMPLETE:
        rv = DoGreetWriteComplete(rv);
        break;
      case STATE_GREET_READ:
        DCHECK_EQ(OK, rv);
        rv = DoGreetRead();
        break;
      case STATE_GREET_READ_COMPLETE:
        rv = DoGreetReadComplete(rv);
        break;
      case STATE_HANDSHAKE_WRITE:
        DCHECK_EQ(OK, rv);
        rv = DoHandshakeWrite();
        break;
      case STATE_HANDSHAKE_WRITE_COMPLETE:
        rv = DoHandshakeWriteComplete(rv);
        break;
      case STATE_HANDSHAKE_READ:
        DCHECK_EQ(OK, rv);
        rv = DoHandshakeRead();
        break;
      case STATE_HANDSHAKE_READ_COMPLETE:
        rv = DoHandshakeReadComplete(rv);
        break;
      default:
        NOTREACHED() << "bad state";
        rv = ERR_UNEXPECTED;
        break;
    }
  } while (rv != ERR_IO_PENDING && next_state_ != STATE_NONE);
  return rv;
}

int SOCKS5ClientSocket::DoResolveHost() {
  DCHECK_EQ(kEndPointUnresolved, address_type_);

  next_state_ = STATE_RESOLVE_HOST_COMPLETE;
  return host_resolver_.Resolve(
      host_request_info_, &addresses_, &io_callback_, NULL);
}

int SOCKS5ClientSocket::DoResolveHostComplete(int result) {
  DCHECK_EQ(kEndPointUnresolved, address_type_);

  bool ok = (result == OK);
  next_state_ = STATE_GREET_WRITE;
  if (ok) {
    DCHECK(addresses_.head());
    struct sockaddr* host_info = addresses_.head()->ai_addr;
    if (host_info->sa_family == AF_INET) {
      address_type_ = kEndPointResolvedIPv4;
    } else if (host_info->sa_family == AF_INET6) {
      address_type_ = kEndPointResolvedIPv6;
    }
  } else {
    address_type_ = kEndPointFailedDomain;
  }

  buffer_.clear();

  // Even if DNS resolution fails, we send OK since the server
  // resolves the domain.
  return OK;
}

const char kSOCKS5GreetWriteData[] = { 0x05, 0x01, 0x00 };  // no authentication
const char kSOCKS5GreetReadData[] = { 0x05, 0x00 };

int SOCKS5ClientSocket::DoGreetWrite() {
  if (buffer_.empty()) {
    buffer_ = std::string(kSOCKS5GreetWriteData,
                          arraysize(kSOCKS5GreetWriteData));
    bytes_sent_ = 0;
  }

  next_state_ = STATE_GREET_WRITE_COMPLETE;
  size_t handshake_buf_len = buffer_.size() - bytes_sent_;
  handshake_buf_ = new IOBuffer(handshake_buf_len);
  memcpy(handshake_buf_->data(), &buffer_.data()[bytes_sent_],
         handshake_buf_len);
  return transport_->Write(handshake_buf_, handshake_buf_len, &io_callback_);
}

int SOCKS5ClientSocket::DoGreetWriteComplete(int result) {
  if (result < 0)
    return result;

  bytes_sent_ += result;
  if (bytes_sent_ == buffer_.size()) {
    buffer_.clear();
    bytes_received_ = 0;
    next_state_ = STATE_GREET_READ;
  } else {
    next_state_ = STATE_GREET_WRITE;
  }
  return OK;
}

int SOCKS5ClientSocket::DoGreetRead() {
  next_state_ = STATE_GREET_READ_COMPLETE;
  size_t handshake_buf_len = kGreetReadHeaderSize - bytes_received_;
  handshake_buf_ = new IOBuffer(handshake_buf_len);
  return transport_->Read(handshake_buf_, handshake_buf_len, &io_callback_);
}

int SOCKS5ClientSocket::DoGreetReadComplete(int result) {
  if (result < 0)
    return result;

  if (result == 0)
    return ERR_CONNECTION_CLOSED;  // Unexpected socket close

  bytes_received_ += result;
  buffer_.append(handshake_buf_->data(), result);
  if (bytes_received_ < kGreetReadHeaderSize) {
    next_state_ = STATE_GREET_READ;
    return OK;
  }

  // Got the greet data.
  if (buffer_[0] != kSOCKS5Version || buffer_[1] != 0x00)
    return ERR_INVALID_RESPONSE;  // Unknown error

  buffer_.clear();
  next_state_ = STATE_HANDSHAKE_WRITE;
  return OK;
}

int SOCKS5ClientSocket::BuildHandshakeWriteBuffer(std::string* handshake)
    const {
  DCHECK_NE(kEndPointUnresolved, address_type_);
  DCHECK(handshake->empty());

  handshake->push_back(kSOCKS5Version);
  handshake->push_back(kTunnelCommand);  // Connect command
  handshake->push_back(kNullByte);  // Reserved null

  handshake->push_back(address_type_);  // The type of connection
  if (address_type_ == kEndPointFailedDomain) {
    if(256 <= host_request_info_.hostname().size())
      return ERR_ADDRESS_INVALID;

    // First add the size of the hostname, followed by the hostname.
    handshake->push_back(static_cast<unsigned char>(
        host_request_info_.hostname().size()));
    handshake->append(host_request_info_.hostname());

  } else if (address_type_ == kEndPointResolvedIPv4) {
    struct sockaddr_in* ipv4_host =
        reinterpret_cast<struct sockaddr_in*>(addresses_.head()->ai_addr);
    handshake->append(reinterpret_cast<char*>(&ipv4_host->sin_addr),
                      sizeof(ipv4_host->sin_addr));

  } else if (address_type_ == kEndPointResolvedIPv6) {
    struct sockaddr_in6* ipv6_host =
        reinterpret_cast<struct sockaddr_in6*>(addresses_.head()->ai_addr);
    handshake->append(reinterpret_cast<char*>(&ipv6_host->sin6_addr),
                      sizeof(ipv6_host->sin6_addr));

  } else {
    NOTREACHED();
  }

  uint16 nw_port = htons(host_request_info_.port());
  handshake->append(reinterpret_cast<char*>(&nw_port), sizeof(nw_port));
  return OK;
}

// Writes the SOCKS handshake data to the underlying socket connection.
int SOCKS5ClientSocket::DoHandshakeWrite() {
  next_state_ = STATE_HANDSHAKE_WRITE_COMPLETE;

  if (buffer_.empty()) {
    int rv = BuildHandshakeWriteBuffer(&buffer_);
    if (rv != OK)
      return rv;
    bytes_sent_ = 0;
  }

  int handshake_buf_len = buffer_.size() - bytes_sent_;
  DCHECK_LT(0, handshake_buf_len);
  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 SOCKS5ClientSocket::DoHandshakeWriteComplete(int result) {
  DCHECK_NE(kEndPointUnresolved, address_type_);

  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_.size()) {
    next_state_ = STATE_HANDSHAKE_READ;
    buffer_.clear();
  } else if (bytes_sent_ < buffer_.size()) {
    next_state_ = STATE_HANDSHAKE_WRITE;
  } else {
    NOTREACHED();
  }

  return OK;
}

int SOCKS5ClientSocket::DoHandshakeRead() {
  DCHECK_NE(kEndPointUnresolved, address_type_);

  next_state_ = STATE_HANDSHAKE_READ_COMPLETE;

  if (buffer_.empty()) {
    bytes_received_ = 0;
    read_header_size = kReadHeaderSize;
  }

  int handshake_buf_len = read_header_size - bytes_received_;
  handshake_buf_ = new IOBuffer(handshake_buf_len);
  return transport_->Read(handshake_buf_, handshake_buf_len, &io_callback_);
}

int SOCKS5ClientSocket::DoHandshakeReadComplete(int result) {
  DCHECK_NE(kEndPointUnresolved, address_type_);

  if (result < 0)
    return result;

  // The underlying socket closed unexpectedly.
  if (result == 0)
    return ERR_CONNECTION_CLOSED;

  buffer_.append(handshake_buf_->data(), result);
  bytes_received_ += result;

  // When the first few bytes are read, check how many more are required
  // and accordingly increase them
  if (bytes_received_ == kReadHeaderSize) {
    // TODO(arindam): add error codes to net/error_list.h
    if (buffer_[0] != kSOCKS5Version || buffer_[2] != kNullByte)
      return ERR_INVALID_RESPONSE;
    if (buffer_[1] != 0x00)
      return ERR_FAILED;

    // We check the type of IP/Domain the server returns and accordingly
    // increase the size of the response. For domains, we need to read the
    // size of the domain, so the initial request size is upto the domain
    // size. Since for IPv4/IPv6 the size is fixed and hence no 'size' is
    // read, we substract 1 byte from the additional request size.
    SocksEndPointAddressType address_type =
        static_cast<SocksEndPointAddressType>(buffer_[3]);
    if (address_type == kEndPointFailedDomain)
      read_header_size += static_cast<uint8>(buffer_[4]);
    else if (address_type == kEndPointResolvedIPv4)
      read_header_size += sizeof(struct in_addr) - 1;
    else if (address_type == kEndPointResolvedIPv6)
      read_header_size += sizeof(struct in6_addr) - 1;
    else
      return ERR_INVALID_RESPONSE;

    read_header_size += 2;  // for the port.
    next_state_ = STATE_HANDSHAKE_READ;
    return OK;
  }

  // When the final bytes are read, setup handshake. We ignore the rest
  // of the response since they represent the SOCKSv5 endpoint and have
  // no use when doing a tunnel connection.
  if (bytes_received_ == read_header_size) {
    completed_handshake_ = true;
    buffer_.clear();
    next_state_ = STATE_NONE;
    return OK;
  }

  next_state_ = STATE_HANDSHAKE_READ;
  return OK;
}

#if defined(OS_LINUX)
int SOCKS5ClientSocket::GetPeerName(struct sockaddr* name,
                                    socklen_t* namelen) {
  return transport_->GetPeerName(name, namelen);
}
#endif

}  // namespace net