shill/http_proxy.cc - mirrors/cros/chromiumos/platform2 - Git at Google

 // Copyright (c) 2012 The Chromium OS 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 "shill/http_proxy.h"

 #include <errno.h>
 #include <netinet/in.h>
 #include <linux/if.h>  // NOLINT - Needs definitions from netinet/in.h
 #include <stdio.h>
 #include <time.h>

 #include <string>
 #include <vector>

 #include <base/bind.h>
 #include <base/strings/string_number_conversions.h>
 #include <base/strings/string_split.h>
 #include <base/strings/string_util.h>
 #include <base/strings/stringprintf.h>

 #include "shill/async_connection.h"
 #include "shill/connection.h"
 #include "shill/dns_client.h"
 #include "shill/event_dispatcher.h"
 #include "shill/logging.h"
 #include "shill/net/ip_address.h"
 #include "shill/net/sockets.h"

 using base::Bind;
 using base::StringPrintf;
 using std::string;
 using std::vector;

 namespace shill {

 namespace Logging {
 static auto kModuleLogScope = ScopeLogger::kHTTPProxy;
 static string ObjectID(Connection *c) {
   return c->interface_name();
 }
 }

 const int HTTPProxy::kClientHeaderTimeoutSeconds = 1;
 const int HTTPProxy::kConnectTimeoutSeconds = 10;
 const int HTTPProxy::kDNSTimeoutSeconds = 5;
 const int HTTPProxy::kDefaultServerPort = 80;
 const int HTTPProxy::kInputTimeoutSeconds = 30;
 const size_t HTTPProxy::kMaxClientQueue = 10;
 const size_t HTTPProxy::kMaxHeaderCount = 128;
 const size_t HTTPProxy::kMaxHeaderSize = 2048;
 const int HTTPProxy::kTransactionTimeoutSeconds = 600;

 const char HTTPProxy::kHTTPMethodConnect[] = "connect";
 const char HTTPProxy::kHTTPMethodTerminator[] = " ";
 const char HTTPProxy::kHTTPURLDelimiters[] = " /#?";
 const char HTTPProxy::kHTTPURLPrefix[] = "http://";
 const char HTTPProxy::kHTTPVersionPrefix[] = " HTTP/1";
 const char HTTPProxy::kInternalErrorMsg[] = "Proxy Failed: Internal Error";

 HTTPProxy::HTTPProxy(ConnectionRefPtr connection)
     : state_(kStateIdle),
       connection_(connection),
       weak_ptr_factory_(this),
       accept_callback_(Bind(&HTTPProxy::AcceptClient,
                             weak_ptr_factory_.GetWeakPtr())),
       connect_completion_callback_(Bind(&HTTPProxy::OnConnectCompletion,
                                         weak_ptr_factory_.GetWeakPtr())),
       dns_client_callback_(Bind(&HTTPProxy::GetDNSResult,
                                 weak_ptr_factory_.GetWeakPtr())),
       read_client_callback_(Bind(&HTTPProxy::ReadFromClient,
                                  weak_ptr_factory_.GetWeakPtr())),
       read_server_callback_(Bind(&HTTPProxy::ReadFromServer,
                                  weak_ptr_factory_.GetWeakPtr())),
       write_client_callback_(Bind(&HTTPProxy::WriteToClient,
                                   weak_ptr_factory_.GetWeakPtr())),
       write_server_callback_(Bind(&HTTPProxy::WriteToServer,
                                   weak_ptr_factory_.GetWeakPtr())),
       dispatcher_(nullptr),
       proxy_port_(-1),
       proxy_socket_(-1),
       sockets_(nullptr),
       client_socket_(-1),
       server_port_(kDefaultServerPort),
       server_socket_(-1),
       is_route_requested_(false) { }

 HTTPProxy::~HTTPProxy() {
   Stop();
 }

 bool HTTPProxy::Start(EventDispatcher *dispatcher,
                       Sockets *sockets) {
   SLOG(connection_.get(), 3) << "In " << __func__;

   if (sockets_) {
     // We are already running.
     return true;
   }

   proxy_socket_ = sockets->Socket(PF_INET, SOCK_STREAM, 0);
   if (proxy_socket_ < 0) {
     PLOG(ERROR) << "Failed to open proxy socket";
     return false;
   }

   struct sockaddr_in addr;
   socklen_t addrlen = sizeof(addr);
   memset(&addr, 0, sizeof(addr));
   addr.sin_family = AF_INET;
   addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
   if (sockets->Bind(proxy_socket_,
                     reinterpret_cast<struct sockaddr *>(&addr),
                     sizeof(addr)) < 0 ||
       sockets->GetSockName(proxy_socket_,
                            reinterpret_cast<struct sockaddr *>(&addr),
                            &addrlen) < 0 ||
       sockets->SetNonBlocking(proxy_socket_) < 0 ||
       sockets->Listen(proxy_socket_, kMaxClientQueue) < 0) {
     sockets->Close(proxy_socket_);
     proxy_socket_ = -1;
     PLOG(ERROR) << "HTTPProxy socket setup failed";
     return false;
   }

   accept_handler_.reset(
       dispatcher->CreateReadyHandler(proxy_socket_, IOHandler::kModeInput,
                                      accept_callback_));
   dispatcher_ = dispatcher;
   dns_client_.reset(new DNSClient(IPAddress::kFamilyIPv4,
                                   connection_->interface_name(),
                                   connection_->dns_servers(),
                                   kDNSTimeoutSeconds * 1000,
                                   dispatcher,
                                   dns_client_callback_));
   proxy_port_ = ntohs(addr.sin_port);
   server_async_connection_.reset(
       new AsyncConnection(connection_->interface_name(), dispatcher, sockets,
                           connect_completion_callback_));
   sockets_ = sockets;
   state_ = kStateWaitConnection;
   return true;
 }

 void HTTPProxy::Stop() {
   SLOG(connection_.get(), 3) << "In " << __func__;

   if (!sockets_) {
     return;
   }

   StopClient();

   accept_handler_.reset();
   dispatcher_ = nullptr;
   dns_client_.reset();
   proxy_port_ = -1;
   server_async_connection_.reset();
   sockets_->Close(proxy_socket_);
   proxy_socket_ = -1;
   sockets_ = nullptr;
   state_ = kStateIdle;
 }

 // IOReadyHandler callback routine fired when a client connects to the
 // proxy's socket.  We Accept() the client and start reading a request
 // from it.
 void HTTPProxy::AcceptClient(int fd) {
   SLOG(connection_.get(), 3) << "In " << __func__;

   int client_fd = sockets_->Accept(fd, nullptr, nullptr);
   if (client_fd < 0) {
     PLOG(ERROR) << "Client accept failed";
     return;
   }

   accept_handler_->Stop();

   client_socket_ = client_fd;

   sockets_->SetNonBlocking(client_socket_);
   read_client_handler_.reset(dispatcher_->CreateInputHandler(
       client_socket_,
       read_client_callback_,
       Bind(&HTTPProxy::OnReadError, weak_ptr_factory_.GetWeakPtr())));
   // Overall transaction timeout.
   transaction_timeout_.Reset(Bind(&HTTPProxy::StopClient,
                                   weak_ptr_factory_.GetWeakPtr()));
   dispatcher_->PostDelayedTask(transaction_timeout_.callback(),
                                kTransactionTimeoutSeconds * 1000);

   state_ = kStateReadClientHeader;
   StartIdleTimeout();
 }

 bool HTTPProxy::ConnectServer(const IPAddress &address, int port) {
   state_ = kStateConnectServer;
   if (!server_async_connection_->Start(address, port)) {
     SendClientError(500, "Could not create socket to connect to server");
     return false;
   }
   StartIdleTimeout();
   return true;
 }

 // DNSClient callback that fires when the DNS request completes.
 void HTTPProxy::GetDNSResult(const Error &error, const IPAddress &address) {
   if (!error.IsSuccess()) {
     SendClientError(502, string("Could not resolve hostname: ") +
                     error.message());
     return;
   }
   ConnectServer(address, server_port_);
 }

 // IOReadyHandler callback routine which fires when the asynchronous Connect()
 // to the remote server completes (or fails).
 void HTTPProxy::OnConnectCompletion(bool success, int fd) {
   if (!success) {
     SendClientError(500, string("Socket connection delayed failure: ") +
                     server_async_connection_->error());
     return;
   }
   server_socket_ = fd;
   state_ = kStateTunnelData;

   // If this was a "CONNECT" request, notify the client that the connection
   // has been established by sending an "OK" response.
   if (LowerCaseEqualsASCII(client_method_, kHTTPMethodConnect)) {
     SetClientResponse(200, "OK", "", "");
     StartReceive();
   }

   StartTransmit();
 }

 void HTTPProxy::OnReadError(const string &error_msg) {
   StopClient();
 }

 // Read through the header lines from the client, modifying or adding
 // lines as necessary.  Perform final determination of the hostname/port
 // we should connect to and either start a DNS request or connect to a
 // numeric address.
 bool HTTPProxy::ParseClientRequest() {
   SLOG(connection_.get(), 3) << "In " << __func__;

   string host;
   bool found_via = false;
   bool found_connection = false;
   for (auto &header : client_headers_) {
     if (StartsWithASCII(header, "Host:", false)) {
       host = header.substr(5);
     } else if (StartsWithASCII(header, "Via:", false)) {
       found_via = true;
       header.append(StringPrintf(", %s shill-proxy", client_version_.c_str()));
     } else if (StartsWithASCII(header, "Connection:", false)) {
       found_connection = true;
       header.assign("Connection: close");
     } else if (StartsWithASCII(header, "Proxy-Connection:", false)) {
       header.assign("Proxy-Connection: close");
     }
   }

   if (!found_connection) {
     client_headers_.push_back("Connection: close");
   }
   if (!found_via) {
     client_headers_.push_back(
         StringPrintf("Via: %s shill-proxy", client_version_.c_str()));
   }

   // Assemble the request as it will be sent to the server.
   client_data_.Clear();
   if (!LowerCaseEqualsASCII(client_method_, kHTTPMethodConnect)) {
     for (const auto &header : client_headers_) {
       client_data_.Append(ByteString(header + "\r\n", false));
     }
     client_data_.Append(ByteString(string("\r\n"), false));
   }

   base::TrimWhitespaceASCII(host, base::TRIM_ALL, &host);
   if (host.empty()) {
     // Revert to using the hostname in the URL if no "Host:" header exists.
     host = server_hostname_;
   }

   if (host.empty()) {
     SendClientError(400, "I don't know what host you want me to connect to");
     return false;
   }

   server_port_ = 80;
   vector<string> host_parts;
   base::SplitString(host, ':', &host_parts);

   if (host_parts.size() > 2) {
     SendClientError(400, "Too many colons in hostname");
     return false;
   } else if (host_parts.size() == 2) {
     server_hostname_ = host_parts[0];
     if (!base::StringToInt(host_parts[1], &server_port_)) {
       SendClientError(400, "Could not parse port number");
       return false;
     }
   } else {
     server_hostname_ = host;
   }

   connection_->RequestRouting();
   is_route_requested_ = true;

   IPAddress addr(IPAddress::kFamilyIPv4);
   if (addr.SetAddressFromString(server_hostname_)) {
     if (!ConnectServer(addr, server_port_)) {
       return false;
     }
   } else {
     SLOG(connection_.get(), 3) << "Looking up host: " << server_hostname_;
     Error error;
     if (!dns_client_->Start(server_hostname_, &error)) {
       SendClientError(502, "Could not resolve hostname: " + error.message());
       return false;
     }
     state_ = kStateLookupServer;
   }
   return true;
 }

 // Accept a new line into the client headers.  Returns false if a parse
 // error occurs.
 bool HTTPProxy::ProcessLastHeaderLine() {
   string *header = &client_headers_.back();
   base::TrimString(*header, "\r", header);

   if (header->empty()) {
     // Empty line terminates client headers.
     client_headers_.pop_back();
     if (!ParseClientRequest()) {
       return false;
     }
   }

   // Is this is the first header line?
   if (client_headers_.size() == 1) {
     if (!ReadClientHTTPMethod(header) ||
         !ReadClientHTTPVersion(header) ||
         !ReadClientHostname(header)) {
       return false;
     }
   }

   if (client_headers_.size() >= kMaxHeaderCount) {
     SendClientError(500, kInternalErrorMsg);
     return false;
   }

   return true;
 }

 // Split input from client into header lines, and consume parsed lines
 // from InputData.  The passed in |data| is modified to indicate the
 // characters consumed.
 bool HTTPProxy::ReadClientHeaders(InputData *data) {
   unsigned char *ptr = data->buf;
   unsigned char *end = ptr + data->len;

   if (client_headers_.empty()) {
     client_headers_.push_back(string());
   }

   for (; ptr < end && state_ == kStateReadClientHeader; ++ptr) {
     if (*ptr == '\n') {
       if (!ProcessLastHeaderLine()) {
         return false;
       }

       // Start a new line.  New chararacters we receive will be appended there.
       client_headers_.push_back(string());
       continue;
     }

     string *header = &client_headers_.back();
     // Is the first character of the header line a space or tab character?
     if (header->empty() && (*ptr == ' ' || *ptr == '\t') &&
         client_headers_.size() > 1) {
       // Line Continuation: Add this character to the previous header line.
       // This way, all of the data (including newlines and line continuation
       // characters) related to a specific header will be contained within
       // a single element of |client_headers_|, and manipulation of headers
       // such as appending will be simpler.  This is accomplished by removing
       // the empty line we started, and instead appending the whitespace
       // and following characters to the previous line.
       client_headers_.pop_back();
       header = &client_headers_.back();
       header->append("\r\n");
     }

     if (header->length() >= kMaxHeaderSize) {
       SendClientError(500, kInternalErrorMsg);
       return false;
     }
     header->push_back(*ptr);
   }

   // Return the remaining data to the caller -- this could be POST data
   // or other non-header data sent with the client request.
   data->buf = ptr;
   data->len = end - ptr;

   return true;
 }

 // Finds the URL in the first line of an HTTP client header, and extracts
 // and removes the hostname (and port) from the URL.  Returns false if a
 // parse error occurs, and true otherwise (whether or not the hostname was
 // found).
 bool HTTPProxy::ReadClientHostname(string *header) {
   const string http_url_prefix(kHTTPURLPrefix);
   size_t url_idx = header->find(http_url_prefix);
   if (url_idx != string::npos) {
     size_t host_start = url_idx + http_url_prefix.length();
     size_t host_end =
       header->find_first_of(kHTTPURLDelimiters, host_start);
     if (host_end != string::npos) {
       server_hostname_ = header->substr(host_start,
                                         host_end - host_start);
       // Modify the URL passed upstream to remove "http://<hostname>".
       header->erase(url_idx, host_end - url_idx);
       if ((*header)[url_idx] != '/') {
         header->insert(url_idx, "/");
       }
     } else {
       LOG(ERROR) << "Could not find end of hostname in request.  Line was: "
                  << *header;
       SendClientError(500, kInternalErrorMsg);
       return false;
     }
   }
   return true;
 }

 bool HTTPProxy::ReadClientHTTPMethod(string *header) {
   size_t method_end = header->find(kHTTPMethodTerminator);
   if (method_end == string::npos || method_end == 0) {
     LOG(ERROR) << "Could not parse HTTP method.  Line was: " << *header;
     SendClientError(501, "Server could not parse HTTP method");
     return false;
   }
   client_method_ = header->substr(0, method_end);
   return true;
 }

 // Extract the HTTP version number from the first line of the client headers.
 // Returns true if found.
 bool HTTPProxy::ReadClientHTTPVersion(string *header) {
   const string http_version_prefix(kHTTPVersionPrefix);
   size_t http_ver_pos = header->find(http_version_prefix);
   if (http_ver_pos != string::npos) {
     client_version_ =
       header->substr(http_ver_pos + http_version_prefix.length() - 1);
   } else {
     SendClientError(501, "Server only accepts HTTP/1.x requests");
     return false;
   }
   return true;
 }

 // IOInputHandler callback that fires when data is read from the client.
 // This could be header data, or perhaps POST data that follows the headers.
 void HTTPProxy::ReadFromClient(InputData *data) {
   SLOG(connection_.get(), 3) << "In " << __func__ << " length " << data->len;

   if (data->len == 0) {
     // EOF from client.
     StopClient();
     return;
   }

   if (state_ == kStateReadClientHeader) {
     if (!ReadClientHeaders(data)) {
       return;
     }
     if (state_ == kStateReadClientHeader) {
       // Still consuming client headers; restart the input timer.
       StartIdleTimeout();
       return;
     }
   }

   // Check data->len again since ReadClientHeaders() may have consumed some
   // part of it.
   if (data->len != 0) {
     // The client sent some information after its headers.  Buffer the client
     // input and temporarily disable input events from the client.
     client_data_.Append(ByteString(data->buf, data->len));
     read_client_handler_->Stop();
     StartTransmit();
   }
 }

 // IOInputHandler callback which fires when data has been read from the
 // server.
 void HTTPProxy::ReadFromServer(InputData *data) {
   SLOG(connection_.get(), 3) << "In " << __func__ << " length " << data->len;
   if (data->len == 0) {
     // Server closed connection.
     if (server_data_.IsEmpty()) {
       StopClient();
       return;
     }
     state_ = kStateFlushResponse;
   } else {
     read_server_handler_->Stop();
   }

   server_data_.Append(ByteString(data->buf, data->len));

   StartTransmit();
 }

 // Return an HTTP error message back to the client.
 void HTTPProxy::SendClientError(int code, const string &error) {
   SLOG(connection_.get(), 3) << "In " << __func__;
   LOG(ERROR) << "Sending error " << error;
   SetClientResponse(code, "ERROR", "text/plain", error);
   state_ = kStateFlushResponse;
   StartTransmit();
 }

 // Create an HTTP response message to be sent to the client.
 void HTTPProxy::SetClientResponse(int code, const string &type,
                                   const string &content_type,
                                   const string &message) {
   string content_line;
   if (!message.empty() && !content_type.empty()) {
     content_line = StringPrintf("Content-Type: %s\r\n", content_type.c_str());
   }
   string response = StringPrintf("HTTP/1.1 %d %s\r\n"
                                  "%s\r\n"
                                  "%s", code, type.c_str(),
                                  content_line.c_str(),
                                  message.c_str());
   server_data_ = ByteString(response, false);
 }

 // Start a timeout for "the next event".  This timeout augments the overall
 // transaction timeout to make sure there is some activity occurring at
 // reasonable intervals.
 void HTTPProxy::StartIdleTimeout() {
   int timeout_seconds = 0;
   switch (state_) {
     case kStateReadClientHeader:
       timeout_seconds = kClientHeaderTimeoutSeconds;
       break;
     case kStateConnectServer:
       timeout_seconds = kConnectTimeoutSeconds;
       break;
     case kStateLookupServer:
       // DNSClient has its own internal timeout, so we need not set one here.
       timeout_seconds = 0;
       break;
     default:
       timeout_seconds = kInputTimeoutSeconds;
       break;
   }
   idle_timeout_.Cancel();
   if (timeout_seconds != 0) {
     idle_timeout_.Reset(Bind(&HTTPProxy::StopClient,
                              weak_ptr_factory_.GetWeakPtr()));
     dispatcher_->PostDelayedTask(idle_timeout_.callback(),
                                  timeout_seconds * 1000);
   }
 }

 // Start the various input handlers.  Listen for new data only if we have
 // completely written the last data we've received to the other end.
 void HTTPProxy::StartReceive() {
   if (state_ == kStateTunnelData && client_data_.IsEmpty()) {
     read_client_handler_->Start();
   }
   if (server_data_.IsEmpty()) {
     if (state_ == kStateTunnelData) {
       if (read_server_handler_.get()) {
         read_server_handler_->Start();
       } else {
         read_server_handler_.reset(dispatcher_->CreateInputHandler(
             server_socket_,
             read_server_callback_,
             Bind(&HTTPProxy::OnReadError, weak_ptr_factory_.GetWeakPtr())));
       }
     } else if (state_ == kStateFlushResponse) {
       StopClient();
       return;
     }
   }
   StartIdleTimeout();
 }

 // Start the various output-ready handlers for the endpoints we have
 // data waiting for.
 void HTTPProxy::StartTransmit() {
   if (state_ == kStateTunnelData && !client_data_.IsEmpty()) {
     if (write_server_handler_.get()) {
       write_server_handler_->Start();
     } else {
       write_server_handler_.reset(
           dispatcher_->CreateReadyHandler(server_socket_,
                                           IOHandler::kModeOutput,
                                           write_server_callback_));
     }
   }
   if ((state_ == kStateFlushResponse || state_ == kStateTunnelData) &&
       !server_data_.IsEmpty()) {
     if (write_client_handler_.get()) {
       write_client_handler_->Start();
     } else {
       write_client_handler_.reset(
           dispatcher_->CreateReadyHandler(client_socket_,
                                           IOHandler::kModeOutput,
                                           write_client_callback_));
     }
   }
   StartIdleTimeout();
 }

 // End the transaction with the current client, restart the IOHandler
 // which alerts us to new clients connecting.  This function is called
 // during various error conditions and is a callback for all timeouts.
 void HTTPProxy::StopClient() {
   SLOG(connection_.get(), 3) << "In " << __func__;

   if (is_route_requested_) {
     connection_->ReleaseRouting();
     is_route_requested_ = false;
   }
   write_client_handler_.reset();
   read_client_handler_.reset();
   if (client_socket_ != -1) {
     sockets_->Close(client_socket_);
     client_socket_ = -1;
   }
   client_headers_.clear();
   client_method_.clear();
   client_version_.clear();
   server_port_ = kDefaultServerPort;
   write_server_handler_.reset();
   read_server_handler_.reset();
   if (server_socket_ != -1) {
     sockets_->Close(server_socket_);
     server_socket_ = -1;
   }
   server_hostname_.clear();
   client_data_.Clear();
   server_data_.Clear();
   dns_client_->Stop();
   server_async_connection_->Stop();
   idle_timeout_.Cancel();
   transaction_timeout_.Cancel();
   accept_handler_->Start();
   state_ = kStateWaitConnection;
 }

 // Output ReadyHandler callback which fires when the client socket is
 // ready for data to be sent to it.
 void HTTPProxy::WriteToClient(int fd) {
   CHECK_EQ(client_socket_, fd);
   int ret = sockets_->Send(fd, server_data_.GetConstData(),
                            server_data_.GetLength(), 0);
   SLOG(connection_.get(), 3) << "In " << __func__ << " wrote " << ret << " of "
                              << server_data_.GetLength();
   if (ret < 0) {
     LOG(ERROR) << "Server write failed";
     StopClient();
     return;
   }

   server_data_ = ByteString(server_data_.GetConstData() + ret,
                             server_data_.GetLength() - ret);

   if (server_data_.IsEmpty()) {
     write_client_handler_->Stop();
   }

   StartReceive();
 }

 // Output ReadyHandler callback which fires when the server socket is
 // ready for data to be sent to it.
 void HTTPProxy::WriteToServer(int fd) {
   CHECK_EQ(server_socket_, fd);
   int ret = sockets_->Send(fd, client_data_.GetConstData(),
                            client_data_.GetLength(), 0);
   SLOG(connection_.get(), 3) << "In " << __func__ << " wrote " << ret << " of "
                              << client_data_.GetLength();

   if (ret < 0) {
     LOG(ERROR) << "Client write failed";
     StopClient();
     return;
   }

   client_data_ = ByteString(client_data_.GetConstData() + ret,
                             client_data_.GetLength() - ret);

   if (client_data_.IsEmpty()) {
     write_server_handler_->Stop();
   }

   StartReceive();
 }

 }  // namespace shill
	// Copyright (c) 2012 The Chromium OS 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 "shill/http_proxy.h"

	#include <errno.h>
	#include <netinet/in.h>
	#include <linux/if.h> // NOLINT - Needs definitions from netinet/in.h
	#include <stdio.h>
	#include <time.h>

	#include <string>
	#include <vector>

	#include <base/bind.h>
	#include <base/strings/string_number_conversions.h>
	#include <base/strings/string_split.h>
	#include <base/strings/string_util.h>
	#include <base/strings/stringprintf.h>

	#include "shill/async_connection.h"
	#include "shill/connection.h"
	#include "shill/dns_client.h"
	#include "shill/event_dispatcher.h"
	#include "shill/logging.h"
	#include "shill/net/ip_address.h"
	#include "shill/net/sockets.h"

	using base::Bind;
	using base::StringPrintf;
	using std::string;
	using std::vector;

	namespace shill {

	namespace Logging {
	static auto kModuleLogScope = ScopeLogger::kHTTPProxy;
	static string ObjectID(Connection *c) {
	return c->interface_name();
	}
	}

	const int HTTPProxy::kClientHeaderTimeoutSeconds = 1;
	const int HTTPProxy::kConnectTimeoutSeconds = 10;
	const int HTTPProxy::kDNSTimeoutSeconds = 5;
	const int HTTPProxy::kDefaultServerPort = 80;
	const int HTTPProxy::kInputTimeoutSeconds = 30;
	const size_t HTTPProxy::kMaxClientQueue = 10;
	const size_t HTTPProxy::kMaxHeaderCount = 128;
	const size_t HTTPProxy::kMaxHeaderSize = 2048;
	const int HTTPProxy::kTransactionTimeoutSeconds = 600;

	const char HTTPProxy::kHTTPMethodConnect[] = "connect";
	const char HTTPProxy::kHTTPMethodTerminator[] = " ";
	const char HTTPProxy::kHTTPURLDelimiters[] = " /#?";
	const char HTTPProxy::kHTTPURLPrefix[] = "http://";
	const char HTTPProxy::kHTTPVersionPrefix[] = " HTTP/1";
	const char HTTPProxy::kInternalErrorMsg[] = "Proxy Failed: Internal Error";

	HTTPProxy::HTTPProxy(ConnectionRefPtr connection)
	: state_(kStateIdle),
	connection_(connection),
	weak_ptr_factory_(this),
	accept_callback_(Bind(&HTTPProxy::AcceptClient,
	weak_ptr_factory_.GetWeakPtr())),
	connect_completion_callback_(Bind(&HTTPProxy::OnConnectCompletion,
	weak_ptr_factory_.GetWeakPtr())),
	dns_client_callback_(Bind(&HTTPProxy::GetDNSResult,
	weak_ptr_factory_.GetWeakPtr())),
	read_client_callback_(Bind(&HTTPProxy::ReadFromClient,
	weak_ptr_factory_.GetWeakPtr())),
	read_server_callback_(Bind(&HTTPProxy::ReadFromServer,
	weak_ptr_factory_.GetWeakPtr())),
	write_client_callback_(Bind(&HTTPProxy::WriteToClient,
	weak_ptr_factory_.GetWeakPtr())),
	write_server_callback_(Bind(&HTTPProxy::WriteToServer,
	weak_ptr_factory_.GetWeakPtr())),
	dispatcher_(nullptr),
	proxy_port_(-1),
	proxy_socket_(-1),
	sockets_(nullptr),
	client_socket_(-1),
	server_port_(kDefaultServerPort),
	server_socket_(-1),
	is_route_requested_(false) { }

	HTTPProxy::~HTTPProxy() {
	Stop();
	}

	bool HTTPProxy::Start(EventDispatcher *dispatcher,
	Sockets *sockets) {
	SLOG(connection_.get(), 3) << "In " << __func__;

	if (sockets_) {
	// We are already running.
	return true;
	}

	proxy_socket_ = sockets->Socket(PF_INET, SOCK_STREAM, 0);
	if (proxy_socket_ < 0) {
	PLOG(ERROR) << "Failed to open proxy socket";
	return false;
	}

	struct sockaddr_in addr;
	socklen_t addrlen = sizeof(addr);
	memset(&addr, 0, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
	if (sockets->Bind(proxy_socket_,
	reinterpret_cast<struct sockaddr *>(&addr),
	sizeof(addr)) < 0 \|\|
	sockets->GetSockName(proxy_socket_,
	reinterpret_cast<struct sockaddr *>(&addr),
	&addrlen) < 0 \|\|
	sockets->SetNonBlocking(proxy_socket_) < 0 \|\|
	sockets->Listen(proxy_socket_, kMaxClientQueue) < 0) {
	sockets->Close(proxy_socket_);
	proxy_socket_ = -1;
	PLOG(ERROR) << "HTTPProxy socket setup failed";
	return false;
	}

	accept_handler_.reset(
	dispatcher->CreateReadyHandler(proxy_socket_, IOHandler::kModeInput,
	accept_callback_));
	dispatcher_ = dispatcher;
	dns_client_.reset(new DNSClient(IPAddress::kFamilyIPv4,
	connection_->interface_name(),
	connection_->dns_servers(),
	kDNSTimeoutSeconds * 1000,
	dispatcher,
	dns_client_callback_));
	proxy_port_ = ntohs(addr.sin_port);
	server_async_connection_.reset(
	new AsyncConnection(connection_->interface_name(), dispatcher, sockets,
	connect_completion_callback_));
	sockets_ = sockets;
	state_ = kStateWaitConnection;
	return true;
	}

	void HTTPProxy::Stop() {
	SLOG(connection_.get(), 3) << "In " << __func__;

	if (!sockets_) {
	return;
	}

	StopClient();

	accept_handler_.reset();
	dispatcher_ = nullptr;
	dns_client_.reset();
	proxy_port_ = -1;
	server_async_connection_.reset();
	sockets_->Close(proxy_socket_);
	proxy_socket_ = -1;
	sockets_ = nullptr;
	state_ = kStateIdle;
	}

	// IOReadyHandler callback routine fired when a client connects to the
	// proxy's socket. We Accept() the client and start reading a request
	// from it.
	void HTTPProxy::AcceptClient(int fd) {
	SLOG(connection_.get(), 3) << "In " << __func__;

	int client_fd = sockets_->Accept(fd, nullptr, nullptr);
	if (client_fd < 0) {
	PLOG(ERROR) << "Client accept failed";
	return;
	}

	accept_handler_->Stop();

	client_socket_ = client_fd;

	sockets_->SetNonBlocking(client_socket_);
	read_client_handler_.reset(dispatcher_->CreateInputHandler(
	client_socket_,
	read_client_callback_,
	Bind(&HTTPProxy::OnReadError, weak_ptr_factory_.GetWeakPtr())));
	// Overall transaction timeout.
	transaction_timeout_.Reset(Bind(&HTTPProxy::StopClient,
	weak_ptr_factory_.GetWeakPtr()));
	dispatcher_->PostDelayedTask(transaction_timeout_.callback(),
	kTransactionTimeoutSeconds * 1000);

	state_ = kStateReadClientHeader;
	StartIdleTimeout();
	}

	bool HTTPProxy::ConnectServer(const IPAddress &address, int port) {
	state_ = kStateConnectServer;
	if (!server_async_connection_->Start(address, port)) {
	SendClientError(500, "Could not create socket to connect to server");
	return false;
	}
	StartIdleTimeout();
	return true;
	}

	// DNSClient callback that fires when the DNS request completes.
	void HTTPProxy::GetDNSResult(const Error &error, const IPAddress &address) {
	if (!error.IsSuccess()) {
	SendClientError(502, string("Could not resolve hostname: ") +
	error.message());
	return;
	}
	ConnectServer(address, server_port_);
	}

	// IOReadyHandler callback routine which fires when the asynchronous Connect()
	// to the remote server completes (or fails).
	void HTTPProxy::OnConnectCompletion(bool success, int fd) {
	if (!success) {
	SendClientError(500, string("Socket connection delayed failure: ") +
	server_async_connection_->error());
	return;
	}
	server_socket_ = fd;
	state_ = kStateTunnelData;

	// If this was a "CONNECT" request, notify the client that the connection
	// has been established by sending an "OK" response.
	if (LowerCaseEqualsASCII(client_method_, kHTTPMethodConnect)) {
	SetClientResponse(200, "OK", "", "");
	StartReceive();
	}

	StartTransmit();
	}

	void HTTPProxy::OnReadError(const string &error_msg) {
	StopClient();
	}

	// Read through the header lines from the client, modifying or adding
	// lines as necessary. Perform final determination of the hostname/port
	// we should connect to and either start a DNS request or connect to a
	// numeric address.
	bool HTTPProxy::ParseClientRequest() {
	SLOG(connection_.get(), 3) << "In " << __func__;

	string host;
	bool found_via = false;
	bool found_connection = false;
	for (auto &header : client_headers_) {
	if (StartsWithASCII(header, "Host:", false)) {
	host = header.substr(5);
	} else if (StartsWithASCII(header, "Via:", false)) {
	found_via = true;
	header.append(StringPrintf(", %s shill-proxy", client_version_.c_str()));
	} else if (StartsWithASCII(header, "Connection:", false)) {
	found_connection = true;
	header.assign("Connection: close");
	} else if (StartsWithASCII(header, "Proxy-Connection:", false)) {
	header.assign("Proxy-Connection: close");
	}
	}

	if (!found_connection) {
	client_headers_.push_back("Connection: close");
	}
	if (!found_via) {
	client_headers_.push_back(
	StringPrintf("Via: %s shill-proxy", client_version_.c_str()));
	}

	// Assemble the request as it will be sent to the server.
	client_data_.Clear();
	if (!LowerCaseEqualsASCII(client_method_, kHTTPMethodConnect)) {
	for (const auto &header : client_headers_) {
	client_data_.Append(ByteString(header + "\r\n", false));
	}
	client_data_.Append(ByteString(string("\r\n"), false));
	}

	base::TrimWhitespaceASCII(host, base::TRIM_ALL, &host);
	if (host.empty()) {
	// Revert to using the hostname in the URL if no "Host:" header exists.
	host = server_hostname_;
	}

	if (host.empty()) {
	SendClientError(400, "I don't know what host you want me to connect to");
	return false;
	}

	server_port_ = 80;
	vector<string> host_parts;
	base::SplitString(host, ':', &host_parts);

	if (host_parts.size() > 2) {
	SendClientError(400, "Too many colons in hostname");
	return false;
	} else if (host_parts.size() == 2) {
	server_hostname_ = host_parts[0];
	if (!base::StringToInt(host_parts[1], &server_port_)) {
	SendClientError(400, "Could not parse port number");
	return false;
	}
	} else {
	server_hostname_ = host;
	}

	connection_->RequestRouting();
	is_route_requested_ = true;

	IPAddress addr(IPAddress::kFamilyIPv4);
	if (addr.SetAddressFromString(server_hostname_)) {
	if (!ConnectServer(addr, server_port_)) {
	return false;
	}
	} else {
	SLOG(connection_.get(), 3) << "Looking up host: " << server_hostname_;
	Error error;
	if (!dns_client_->Start(server_hostname_, &error)) {
	SendClientError(502, "Could not resolve hostname: " + error.message());
	return false;
	}
	state_ = kStateLookupServer;
	}
	return true;
	}

	// Accept a new line into the client headers. Returns false if a parse
	// error occurs.
	bool HTTPProxy::ProcessLastHeaderLine() {
	string *header = &client_headers_.back();
	base::TrimString(*header, "\r", header);

	if (header->empty()) {
	// Empty line terminates client headers.
	client_headers_.pop_back();
	if (!ParseClientRequest()) {
	return false;
	}
	}

	// Is this is the first header line?
	if (client_headers_.size() == 1) {
	if (!ReadClientHTTPMethod(header) \|\|
	!ReadClientHTTPVersion(header) \|\|
	!ReadClientHostname(header)) {
	return false;
	}
	}

	if (client_headers_.size() >= kMaxHeaderCount) {
	SendClientError(500, kInternalErrorMsg);
	return false;
	}

	return true;
	}

	// Split input from client into header lines, and consume parsed lines
	// from InputData. The passed in \|data\| is modified to indicate the
	// characters consumed.
	bool HTTPProxy::ReadClientHeaders(InputData *data) {
	unsigned char *ptr = data->buf;
	unsigned char *end = ptr + data->len;

	if (client_headers_.empty()) {
	client_headers_.push_back(string());
	}

	for (; ptr < end && state_ == kStateReadClientHeader; ++ptr) {
	if (*ptr == '\n') {
	if (!ProcessLastHeaderLine()) {
	return false;
	}

	// Start a new line. New chararacters we receive will be appended there.
	client_headers_.push_back(string());
	continue;
	}

	string *header = &client_headers_.back();
	// Is the first character of the header line a space or tab character?
	if (header->empty() && (ptr == ' ' \|\| ptr == '\t') &&
	client_headers_.size() > 1) {
	// Line Continuation: Add this character to the previous header line.
	// This way, all of the data (including newlines and line continuation
	// characters) related to a specific header will be contained within
	// a single element of \|client_headers_\|, and manipulation of headers
	// such as appending will be simpler. This is accomplished by removing
	// the empty line we started, and instead appending the whitespace
	// and following characters to the previous line.
	client_headers_.pop_back();
	header = &client_headers_.back();
	header->append("\r\n");
	}

	if (header->length() >= kMaxHeaderSize) {
	SendClientError(500, kInternalErrorMsg);
	return false;
	}
	header->push_back(*ptr);
	}

	// Return the remaining data to the caller -- this could be POST data
	// or other non-header data sent with the client request.
	data->buf = ptr;
	data->len = end - ptr;

	return true;
	}

	// Finds the URL in the first line of an HTTP client header, and extracts
	// and removes the hostname (and port) from the URL. Returns false if a
	// parse error occurs, and true otherwise (whether or not the hostname was
	// found).
	bool HTTPProxy::ReadClientHostname(string *header) {
	const string http_url_prefix(kHTTPURLPrefix);
	size_t url_idx = header->find(http_url_prefix);
	if (url_idx != string::npos) {
	size_t host_start = url_idx + http_url_prefix.length();
	size_t host_end =
	header->find_first_of(kHTTPURLDelimiters, host_start);
	if (host_end != string::npos) {
	server_hostname_ = header->substr(host_start,
	host_end - host_start);
	// Modify the URL passed upstream to remove "http://<hostname>".
	header->erase(url_idx, host_end - url_idx);
	if ((*header)[url_idx] != '/') {
	header->insert(url_idx, "/");
	}
	} else {
	LOG(ERROR) << "Could not find end of hostname in request. Line was: "
	<< *header;
	SendClientError(500, kInternalErrorMsg);
	return false;
	}
	}
	return true;
	}

	bool HTTPProxy::ReadClientHTTPMethod(string *header) {
	size_t method_end = header->find(kHTTPMethodTerminator);
	if (method_end == string::npos \|\| method_end == 0) {
	LOG(ERROR) << "Could not parse HTTP method. Line was: " << *header;
	SendClientError(501, "Server could not parse HTTP method");
	return false;
	}
	client_method_ = header->substr(0, method_end);
	return true;
	}

	// Extract the HTTP version number from the first line of the client headers.
	// Returns true if found.
	bool HTTPProxy::ReadClientHTTPVersion(string *header) {
	const string http_version_prefix(kHTTPVersionPrefix);
	size_t http_ver_pos = header->find(http_version_prefix);
	if (http_ver_pos != string::npos) {
	client_version_ =
	header->substr(http_ver_pos + http_version_prefix.length() - 1);
	} else {
	SendClientError(501, "Server only accepts HTTP/1.x requests");
	return false;
	}
	return true;
	}

	// IOInputHandler callback that fires when data is read from the client.
	// This could be header data, or perhaps POST data that follows the headers.
	void HTTPProxy::ReadFromClient(InputData *data) {
	SLOG(connection_.get(), 3) << "In " << __func__ << " length " << data->len;

	if (data->len == 0) {
	// EOF from client.
	StopClient();
	return;
	}

	if (state_ == kStateReadClientHeader) {
	if (!ReadClientHeaders(data)) {
	return;
	}
	if (state_ == kStateReadClientHeader) {
	// Still consuming client headers; restart the input timer.
	StartIdleTimeout();
	return;
	}
	}

	// Check data->len again since ReadClientHeaders() may have consumed some
	// part of it.
	if (data->len != 0) {
	// The client sent some information after its headers. Buffer the client
	// input and temporarily disable input events from the client.
	client_data_.Append(ByteString(data->buf, data->len));
	read_client_handler_->Stop();
	StartTransmit();
	}
	}

	// IOInputHandler callback which fires when data has been read from the
	// server.
	void HTTPProxy::ReadFromServer(InputData *data) {
	SLOG(connection_.get(), 3) << "In " << __func__ << " length " << data->len;
	if (data->len == 0) {
	// Server closed connection.
	if (server_data_.IsEmpty()) {
	StopClient();
	return;
	}
	state_ = kStateFlushResponse;
	} else {
	read_server_handler_->Stop();
	}

	server_data_.Append(ByteString(data->buf, data->len));

	StartTransmit();
	}

	// Return an HTTP error message back to the client.
	void HTTPProxy::SendClientError(int code, const string &error) {
	SLOG(connection_.get(), 3) << "In " << __func__;
	LOG(ERROR) << "Sending error " << error;
	SetClientResponse(code, "ERROR", "text/plain", error);
	state_ = kStateFlushResponse;
	StartTransmit();
	}

	// Create an HTTP response message to be sent to the client.
	void HTTPProxy::SetClientResponse(int code, const string &type,
	const string &content_type,
	const string &message) {
	string content_line;
	if (!message.empty() && !content_type.empty()) {
	content_line = StringPrintf("Content-Type: %s\r\n", content_type.c_str());
	}
	string response = StringPrintf("HTTP/1.1 %d %s\r\n"
	"%s\r\n"
	"%s", code, type.c_str(),
	content_line.c_str(),
	message.c_str());
	server_data_ = ByteString(response, false);
	}

	// Start a timeout for "the next event". This timeout augments the overall
	// transaction timeout to make sure there is some activity occurring at
	// reasonable intervals.
	void HTTPProxy::StartIdleTimeout() {
	int timeout_seconds = 0;
	switch (state_) {
	case kStateReadClientHeader:
	timeout_seconds = kClientHeaderTimeoutSeconds;
	break;
	case kStateConnectServer:
	timeout_seconds = kConnectTimeoutSeconds;
	break;
	case kStateLookupServer:
	// DNSClient has its own internal timeout, so we need not set one here.
	timeout_seconds = 0;
	break;
	default:
	timeout_seconds = kInputTimeoutSeconds;
	break;
	}
	idle_timeout_.Cancel();
	if (timeout_seconds != 0) {
	idle_timeout_.Reset(Bind(&HTTPProxy::StopClient,
	weak_ptr_factory_.GetWeakPtr()));
	dispatcher_->PostDelayedTask(idle_timeout_.callback(),
	timeout_seconds * 1000);
	}
	}

	// Start the various input handlers. Listen for new data only if we have
	// completely written the last data we've received to the other end.
	void HTTPProxy::StartReceive() {
	if (state_ == kStateTunnelData && client_data_.IsEmpty()) {
	read_client_handler_->Start();
	}
	if (server_data_.IsEmpty()) {
	if (state_ == kStateTunnelData) {
	if (read_server_handler_.get()) {
	read_server_handler_->Start();
	} else {
	read_server_handler_.reset(dispatcher_->CreateInputHandler(
	server_socket_,
	read_server_callback_,
	Bind(&HTTPProxy::OnReadError, weak_ptr_factory_.GetWeakPtr())));
	}
	} else if (state_ == kStateFlushResponse) {
	StopClient();
	return;
	}
	}
	StartIdleTimeout();
	}

	// Start the various output-ready handlers for the endpoints we have
	// data waiting for.
	void HTTPProxy::StartTransmit() {
	if (state_ == kStateTunnelData && !client_data_.IsEmpty()) {
	if (write_server_handler_.get()) {
	write_server_handler_->Start();
	} else {
	write_server_handler_.reset(
	dispatcher_->CreateReadyHandler(server_socket_,
	IOHandler::kModeOutput,
	write_server_callback_));
	}
	}
	if ((state_ == kStateFlushResponse \|\| state_ == kStateTunnelData) &&
	!server_data_.IsEmpty()) {
	if (write_client_handler_.get()) {
	write_client_handler_->Start();
	} else {
	write_client_handler_.reset(
	dispatcher_->CreateReadyHandler(client_socket_,
	IOHandler::kModeOutput,
	write_client_callback_));
	}
	}
	StartIdleTimeout();
	}

	// End the transaction with the current client, restart the IOHandler
	// which alerts us to new clients connecting. This function is called
	// during various error conditions and is a callback for all timeouts.
	void HTTPProxy::StopClient() {
	SLOG(connection_.get(), 3) << "In " << __func__;

	if (is_route_requested_) {
	connection_->ReleaseRouting();
	is_route_requested_ = false;
	}
	write_client_handler_.reset();
	read_client_handler_.reset();
	if (client_socket_ != -1) {
	sockets_->Close(client_socket_);
	client_socket_ = -1;
	}
	client_headers_.clear();
	client_method_.clear();
	client_version_.clear();
	server_port_ = kDefaultServerPort;
	write_server_handler_.reset();
	read_server_handler_.reset();
	if (server_socket_ != -1) {
	sockets_->Close(server_socket_);
	server_socket_ = -1;
	}
	server_hostname_.clear();
	client_data_.Clear();
	server_data_.Clear();
	dns_client_->Stop();
	server_async_connection_->Stop();
	idle_timeout_.Cancel();
	transaction_timeout_.Cancel();
	accept_handler_->Start();
	state_ = kStateWaitConnection;
	}

	// Output ReadyHandler callback which fires when the client socket is
	// ready for data to be sent to it.
	void HTTPProxy::WriteToClient(int fd) {
	CHECK_EQ(client_socket_, fd);
	int ret = sockets_->Send(fd, server_data_.GetConstData(),
	server_data_.GetLength(), 0);
	SLOG(connection_.get(), 3) << "In " << __func__ << " wrote " << ret << " of "
	<< server_data_.GetLength();
	if (ret < 0) {
	LOG(ERROR) << "Server write failed";
	StopClient();
	return;
	}

	server_data_ = ByteString(server_data_.GetConstData() + ret,
	server_data_.GetLength() - ret);

	if (server_data_.IsEmpty()) {
	write_client_handler_->Stop();
	}

	StartReceive();
	}

	// Output ReadyHandler callback which fires when the server socket is
	// ready for data to be sent to it.
	void HTTPProxy::WriteToServer(int fd) {
	CHECK_EQ(server_socket_, fd);
	int ret = sockets_->Send(fd, client_data_.GetConstData(),
	client_data_.GetLength(), 0);
	SLOG(connection_.get(), 3) << "In " << __func__ << " wrote " << ret << " of "
	<< client_data_.GetLength();

	if (ret < 0) {
	LOG(ERROR) << "Client write failed";
	StopClient();
	return;
	}

	client_data_ = ByteString(client_data_.GetConstData() + ret,
	client_data_.GetLength() - ret);

	if (client_data_.IsEmpty()) {
	write_server_handler_->Stop();
	}

	StartReceive();
	}

	} // namespace shill