port_util.cc

// Copyright (c) 2012 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/base/port_util.h"

#include <limits>
#include <set>

#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "url/url_constants.h"

namespace net {

namespace {

// The general list of blocked ports. Will be blocked unless a specific
// protocol overrides it. (Ex: ftp can use ports 20 and 21)
const int kRestrictedPorts[] = {
    1,       // tcpmux
    7,       // echo
    9,       // discard
    11,      // systat
    13,      // daytime
    15,      // netstat
    17,      // qotd
    19,      // chargen
    20,      // ftp data
    21,      // ftp access
    22,      // ssh
    23,      // telnet
    25,      // smtp
    37,      // time
    42,      // name
    43,      // nicname
    53,      // domain
    77,      // priv-rjs
    79,      // finger
    87,      // ttylink
    95,      // supdup
    101,     // hostriame
    102,     // iso-tsap
    103,     // gppitnp
    104,     // acr-nema
    109,     // pop2
    110,     // pop3
    111,     // sunrpc
    113,     // auth
    115,     // sftp
    117,     // uucp-path
    119,     // nntp
    123,     // NTP
    135,     // loc-srv /epmap
    139,     // netbios
    143,     // imap2
    179,     // BGP
    389,     // ldap
    427,     // SLP (Also used by Apple Filing Protocol)
    465,     // smtp+ssl
    512,     // print / exec
    513,     // login
    514,     // shell
    515,     // printer
    526,     // tempo
    530,     // courier
    531,     // chat
    532,     // netnews
    540,     // uucp
    548,     // AFP (Apple Filing Protocol)
    556,     // remotefs
    563,     // nntp+ssl
    587,     // stmp?
    601,     // ??
    636,     // ldap+ssl
    993,     // ldap+ssl
    995,     // pop3+ssl
    2049,    // nfs
    3659,    // apple-sasl / PasswordServer
    4045,    // lockd
    6000,    // X11
    6665,    // Alternate IRC [Apple addition]
    6666,    // Alternate IRC [Apple addition]
    6667,    // Standard IRC [Apple addition]
    6668,    // Alternate IRC [Apple addition]
    6669,    // Alternate IRC [Apple addition]
    6697,    // IRC + TLS
};

// FTP overrides the following restricted port.
const int kAllowedFtpPorts[] = {
    21,  // ftp data
};

base::LazyInstance<std::multiset<int>>::Leaky g_explicitly_allowed_ports =
    LAZY_INSTANCE_INITIALIZER;

}  // namespace

bool IsPortValid(int port) {
  return port >= 0 && port <= std::numeric_limits<uint16_t>::max();
}

bool IsWellKnownPort(int port) {
  return port >= 0 && port < 1024;
}

bool IsPortAllowedForScheme(int port, const std::string& url_scheme) {
  // Reject invalid ports.
  if (!IsPortValid(port))
    return false;

  // Allow explitly allowed ports for any scheme.
  if (g_explicitly_allowed_ports.Get().count(port) > 0)
    return true;

  // FTP requests have an extra set of whitelisted schemes.
  if (base::LowerCaseEqualsASCII(url_scheme, url::kFtpScheme)) {
    for (int allowed_ftp_port : kAllowedFtpPorts) {
      if (allowed_ftp_port == port)
        return true;
    }
  }

  // Finally check against the generic list of restricted ports for all
  // schemes.
  for (int restricted_port : kRestrictedPorts) {
    if (restricted_port == port)
      return false;
  }

  return true;
}

size_t GetCountOfExplicitlyAllowedPorts() {
  return g_explicitly_allowed_ports.Get().size();
}

// Specifies a comma separated list of port numbers that should be accepted
// despite bans. If the string is invalid no allowed ports are stored.
void SetExplicitlyAllowedPorts(const std::string& allowed_ports) {
  if (allowed_ports.empty())
    return;

  std::multiset<int> ports;
  size_t last = 0;
  size_t size = allowed_ports.size();
  // The comma delimiter.
  const std::string::value_type kComma = ',';

  // Overflow is still possible for evil user inputs.
  for (size_t i = 0; i <= size; ++i) {
    // The string should be composed of only digits and commas.
    if (i != size && !base::IsAsciiDigit(allowed_ports[i]) &&
        (allowed_ports[i] != kComma))
      return;
    if (i == size || allowed_ports[i] == kComma) {
      if (i > last) {
        int port;
        base::StringToInt(base::StringPiece(allowed_ports.begin() + last,
                                            allowed_ports.begin() + i),
                          &port);
        ports.insert(port);
      }
      last = i + 1;
    }
  }
  g_explicitly_allowed_ports.Get() = ports;
}

ScopedPortException::ScopedPortException(int port) : port_(port) {
  g_explicitly_allowed_ports.Get().insert(port);
}

ScopedPortException::~ScopedPortException() {
  auto it = g_explicitly_allowed_ports.Get().find(port_);
  if (it != g_explicitly_allowed_ports.Get().end())
    g_explicitly_allowed_ports.Get().erase(it);
  else
    NOTREACHED();
}

}  // namespace net