net/socket/tcp_socket.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/socket/tcp_socket.h"
   6
   7 #include "base/file_util.h"
   8 #include "base/files/file_path.h"
   9
  10 namespace net {
  11
  12 namespace {
  13
  14 #if defined(OS_LINUX)
  15
  16 // Checks to see if the system supports TCP FastOpen. Notably, it requires
  17 // kernel support. Additionally, this checks system configuration to ensure that
  18 // it's enabled.
  19 bool SystemSupportsTCPFastOpen() {
  20   static const base::FilePath::CharType kTCPFastOpenProcFilePath[] =
  21       "/proc/sys/net/ipv4/tcp_fastopen";
  22   std::string system_enabled_tcp_fastopen;
  23   if (!base::ReadFileToString(
  24           base::FilePath(kTCPFastOpenProcFilePath),
  25           &system_enabled_tcp_fastopen)) {
  26     return false;
  27   }
  28
  29   // As per http://lxr.linux.no/linux+v3.7.7/include/net/tcp.h#L225
  30   // TFO_CLIENT_ENABLE is the LSB
  31   if (system_enabled_tcp_fastopen.empty() ||
  32       (system_enabled_tcp_fastopen[0] & 0x1) == 0) {
  33     return false;
  34   }
  35
  36   return true;
  37 }
  38
  39 #else
  40
  41 bool SystemSupportsTCPFastOpen() {
  42   return false;
  43 }
  44
  45 #endif
  46
  47 bool g_tcp_fastopen_enabled = false;
  48
  49 }  // namespace
  50
  51 void SetTCPFastOpenEnabled(bool value) {
  52   g_tcp_fastopen_enabled = value && SystemSupportsTCPFastOpen();
  53 }
  54
  55 bool IsTCPFastOpenEnabled() {
  56   return g_tcp_fastopen_enabled;
  57 }
  58
  59 }  // namespace net