net/base/ip_address.cc

// Copyright (c) 2015 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/ip_address.h"

#include <limits.h>

#include "base/strings/string_piece.h"
#include "base/strings/string_split.h"
#include "base/strings/stringprintf.h"
#include "net/base/parse_number.h"
#include "url/gurl.h"
#include "url/url_canon_ip.h"

namespace {

// The prefix for IPv6 mapped IPv4 addresses.
// https://tools.ietf.org/html/rfc4291#section-2.5.5.2
const uint8_t kIPv4MappedPrefix[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF};

// Note that this function assumes:
// * |ip_address| is at least |prefix_length_in_bits| (bits) long;
// * |ip_prefix| is at least |prefix_length_in_bits| (bits) long.
bool IPAddressPrefixCheck(const std::vector<uint8_t>& ip_address,
                          const uint8_t* ip_prefix,
                          size_t prefix_length_in_bits) {
  // Compare all the bytes that fall entirely within the prefix.
  size_t num_entire_bytes_in_prefix = prefix_length_in_bits / 8;
  for (size_t i = 0; i < num_entire_bytes_in_prefix; ++i) {
    if (ip_address[i] != ip_prefix[i])
      return false;
  }

  // In case the prefix was not a multiple of 8, there will be 1 byte
  // which is only partially masked.
  size_t remaining_bits = prefix_length_in_bits % 8;
  if (remaining_bits != 0) {
    uint8_t mask = 0xFF << (8 - remaining_bits);
    size_t i = num_entire_bytes_in_prefix;
    if ((ip_address[i] & mask) != (ip_prefix[i] & mask))
      return false;
  }
  return true;
}

// Returns true if |ip_address| matches any of the reserved IPv4 ranges. This
// method operates on a blacklist of reserved IPv4 ranges. Some ranges are
// consolidated.
// Sources for info:
// www.iana.org/assignments/ipv4-address-space/ipv4-address-space.xhtml
// www.iana.org/assignments/iana-ipv4-special-registry/
// iana-ipv4-special-registry.xhtml
bool IsReservedIPv4(const std::vector<uint8_t>& ip_address) {
  // Different IP versions have different range reservations.
  DCHECK_EQ(net::IPAddress::kIPv4AddressSize, ip_address.size());
  struct {
    const uint8_t address[4];
    size_t prefix_length_in_bits;
  } static const kReservedIPv4Ranges[] = {
      {{0, 0, 0, 0}, 8},     {{10, 0, 0, 0}, 8},      {{100, 64, 0, 0}, 10},
      {{127, 0, 0, 0}, 8},   {{169, 254, 0, 0}, 16},  {{172, 16, 0, 0}, 12},
      {{192, 0, 2, 0}, 24},  {{192, 88, 99, 0}, 24},  {{192, 168, 0, 0}, 16},
      {{198, 18, 0, 0}, 15}, {{198, 51, 100, 0}, 24}, {{203, 0, 113, 0}, 24},
      {{224, 0, 0, 0}, 3}};

  for (const auto& range : kReservedIPv4Ranges) {
    if (IPAddressPrefixCheck(ip_address, range.address,
                             range.prefix_length_in_bits)) {
      return true;
    }
  }

  return false;
}

// Returns true if |ip_address| matches any of the reserved IPv6 ranges. This
// method operates on a whitelist of non-reserved IPv6 ranges. All IPv6
// addresses outside these ranges are reserved.
// Sources for info:
// www.iana.org/assignments/ipv6-address-space/ipv6-address-space.xhtml
bool IsReservedIPv6(const std::vector<uint8_t>& ip_address) {
  // Different IP versions have different range reservations.
  DCHECK_EQ(net::IPAddress::kIPv6AddressSize, ip_address.size());
  struct {
    const uint8_t address_prefix[2];
    size_t prefix_length_in_bits;
  } static const kPublicIPv6Ranges[] = {
      // 2000::/3  -- Global Unicast
      {{0x20, 0}, 3},
      // ff00::/8  -- Multicast
      {{0xff, 0}, 8},
  };

  for (const auto& range : kPublicIPv6Ranges) {
    if (IPAddressPrefixCheck(ip_address, range.address_prefix,
                             range.prefix_length_in_bits)) {
      return false;
    }
  }

  return true;
}

bool ParseIPLiteralToBytes(const base::StringPiece& ip_literal,
                           std::vector<uint8_t>* bytes) {
  // |ip_literal| could be either an IPv4 or an IPv6 literal. If it contains
  // a colon however, it must be an IPv6 address.
  if (ip_literal.find(':') != base::StringPiece::npos) {
    // GURL expects IPv6 hostnames to be surrounded with brackets.
    std::string host_brackets = "[";
    ip_literal.AppendToString(&host_brackets);
    host_brackets.push_back(']');
    url::Component host_comp(0, host_brackets.size());

    // Try parsing the hostname as an IPv6 literal.
    bytes->resize(16);  // 128 bits.
    return url::IPv6AddressToNumber(host_brackets.data(), host_comp,
                                    bytes->data());
  }

  // Otherwise the string is an IPv4 address.
  bytes->resize(4);  // 32 bits.
  url::Component host_comp(0, ip_literal.size());
  int num_components;
  url::CanonHostInfo::Family family = url::IPv4AddressToNumber(
      ip_literal.data(), host_comp, bytes->data(), &num_components);
  return family == url::CanonHostInfo::IPV4;
}

}  // namespace

namespace net {

IPAddress::IPAddress() {}

IPAddress::IPAddress(const std::vector<uint8_t>& address)
    : ip_address_(address) {}

IPAddress::IPAddress(const IPAddress& other) = default;

IPAddress::IPAddress(const uint8_t* address, size_t address_len)
    : ip_address_(address, address + address_len) {}

IPAddress::IPAddress(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3) {
  ip_address_.reserve(4);
  ip_address_.push_back(b0);
  ip_address_.push_back(b1);
  ip_address_.push_back(b2);
  ip_address_.push_back(b3);
}

IPAddress::IPAddress(uint8_t b0,
                     uint8_t b1,
                     uint8_t b2,
                     uint8_t b3,
                     uint8_t b4,
                     uint8_t b5,
                     uint8_t b6,
                     uint8_t b7,
                     uint8_t b8,
                     uint8_t b9,
                     uint8_t b10,
                     uint8_t b11,
                     uint8_t b12,
                     uint8_t b13,
                     uint8_t b14,
                     uint8_t b15) {
  const uint8_t address[] = {b0, b1, b2,  b3,  b4,  b5,  b6,  b7,
                             b8, b9, b10, b11, b12, b13, b14, b15};
  ip_address_ = std::vector<uint8_t>(std::begin(address), std::end(address));
}

IPAddress::~IPAddress() {}

bool IPAddress::IsIPv4() const {
  return ip_address_.size() == kIPv4AddressSize;
}

bool IPAddress::IsIPv6() const {
  return ip_address_.size() == kIPv6AddressSize;
}

bool IPAddress::IsValid() const {
  return IsIPv4() || IsIPv6();
}

bool IPAddress::IsReserved() const {
  if (IsIPv4()) {
    return IsReservedIPv4(ip_address_);
  } else if (IsIPv6()) {
    return IsReservedIPv6(ip_address_);
  }
  return false;
}

bool IPAddress::IsZero() const {
  for (auto x : ip_address_) {
    if (x != 0)
      return false;
  }

  return !empty();
}

bool IPAddress::IsIPv4MappedIPv6() const {
  return IsIPv6() && IPAddressStartsWith(*this, kIPv4MappedPrefix);
}

bool IPAddress::AssignFromIPLiteral(const base::StringPiece& ip_literal) {
  std::vector<uint8_t> number;

  if (!ParseIPLiteralToBytes(ip_literal, &number))
    return false;

  std::swap(number, ip_address_);
  return true;
}

// static
IPAddress IPAddress::IPv4Localhost() {
  static const uint8_t kLocalhostIPv4[] = {127, 0, 0, 1};
  return IPAddress(kLocalhostIPv4);
}

// static
IPAddress IPAddress::IPv6Localhost() {
  static const uint8_t kLocalhostIPv6[] = {0, 0, 0, 0, 0, 0, 0, 0,
                                           0, 0, 0, 0, 0, 0, 0, 1};
  return IPAddress(kLocalhostIPv6);
}

// static
IPAddress IPAddress::AllZeros(size_t num_zero_bytes) {
  return IPAddress(std::vector<uint8_t>(num_zero_bytes));
}

// static
IPAddress IPAddress::IPv4AllZeros() {
  return AllZeros(kIPv4AddressSize);
}

// static
IPAddress IPAddress::IPv6AllZeros() {
  return AllZeros(kIPv6AddressSize);
}

bool IPAddress::operator==(const IPAddress& that) const {
  return ip_address_ == that.ip_address_;
}

bool IPAddress::operator!=(const IPAddress& that) const {
  return ip_address_ != that.ip_address_;
}

bool IPAddress::operator<(const IPAddress& that) const {
  // Sort IPv4 before IPv6.
  if (ip_address_.size() != that.ip_address_.size()) {
    return ip_address_.size() < that.ip_address_.size();
  }

  return ip_address_ < that.ip_address_;
}

std::string IPAddress::ToString() const {
  std::string str;
  url::StdStringCanonOutput output(&str);

  if (IsIPv4()) {
    url::AppendIPv4Address(ip_address_.data(), &output);
  } else if (IsIPv6()) {
    url::AppendIPv6Address(ip_address_.data(), &output);
  }

  output.Complete();
  return str;
}

std::string IPAddressToStringWithPort(const IPAddress& address, uint16_t port) {
  std::string address_str = address.ToString();
  if (address_str.empty())
    return address_str;

  if (address.IsIPv6()) {
    // Need to bracket IPv6 addresses since they contain colons.
    return base::StringPrintf("[%s]:%d", address_str.c_str(), port);
  }
  return base::StringPrintf("%s:%d", address_str.c_str(), port);
}

std::string IPAddressToPackedString(const IPAddress& address) {
  return std::string(reinterpret_cast<const char*>(address.bytes().data()),
                     address.size());
}

IPAddress ConvertIPv4ToIPv4MappedIPv6(const IPAddress& address) {
  DCHECK(address.IsIPv4());
  // IPv4-mapped addresses are formed by:
  // <80 bits of zeros>  + <16 bits of ones> + <32-bit IPv4 address>.
  std::vector<uint8_t> bytes;
  bytes.reserve(16);
  bytes.insert(bytes.end(), std::begin(kIPv4MappedPrefix),
               std::end(kIPv4MappedPrefix));
  bytes.insert(bytes.end(), address.bytes().begin(), address.bytes().end());
  return IPAddress(bytes);
}

IPAddress ConvertIPv4MappedIPv6ToIPv4(const IPAddress& address) {
  DCHECK(address.IsIPv4MappedIPv6());

  return IPAddress(std::vector<uint8_t>(
      address.bytes().begin() + arraysize(kIPv4MappedPrefix),
      address.bytes().end()));
}

bool IPAddressMatchesPrefix(const IPAddress& ip_address,
                            const IPAddress& ip_prefix,
                            size_t prefix_length_in_bits) {
  // Both the input IP address and the prefix IP address should be either IPv4
  // or IPv6.
  DCHECK(ip_address.IsValid());
  DCHECK(ip_prefix.IsValid());

  DCHECK_LE(prefix_length_in_bits, ip_prefix.size() * 8);

  // In case we have an IPv6 / IPv4 mismatch, convert the IPv4 addresses to
  // IPv6 addresses in order to do the comparison.
  if (ip_address.size() != ip_prefix.size()) {
    if (ip_address.IsIPv4()) {
      return IPAddressMatchesPrefix(ConvertIPv4ToIPv4MappedIPv6(ip_address),
                                    ip_prefix, prefix_length_in_bits);
    }
    return IPAddressMatchesPrefix(ip_address,
                                  ConvertIPv4ToIPv4MappedIPv6(ip_prefix),
                                  96 + prefix_length_in_bits);
  }

  return IPAddressPrefixCheck(ip_address.bytes(), ip_prefix.bytes().data(),
                              prefix_length_in_bits);
}

bool ParseCIDRBlock(const std::string& cidr_literal,
                    IPAddress* ip_address,
                    size_t* prefix_length_in_bits) {
  // We expect CIDR notation to match one of these two templates:
  //   <IPv4-literal> "/" <number of bits>
  //   <IPv6-literal> "/" <number of bits>

  std::vector<base::StringPiece> parts = base::SplitStringPiece(
      cidr_literal, "/", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
  if (parts.size() != 2)
    return false;

  // Parse the IP address.
  if (!ip_address->AssignFromIPLiteral(parts[0]))
    return false;

  // Parse the prefix length.
  uint32_t number_of_bits;
  if (!ParseUint32(parts[1], &number_of_bits))
    return false;

  // Make sure the prefix length is in a valid range.
  if (number_of_bits > ip_address->size() * 8)
    return false;

  *prefix_length_in_bits = number_of_bits;
  return true;
}

bool ParseURLHostnameToAddress(const base::StringPiece& hostname,
                               IPAddress* ip_address) {
  if (hostname.size() >= 2 && hostname.front() == '[' &&
      hostname.back() == ']') {
    // Strip the square brackets that surround IPv6 literals.
    auto ip_literal =
        base::StringPiece(hostname).substr(1, hostname.size() - 2);
    return ip_address->AssignFromIPLiteral(ip_literal) && ip_address->IsIPv6();
  }

  return ip_address->AssignFromIPLiteral(hostname) && ip_address->IsIPv4();
}

unsigned CommonPrefixLength(const IPAddress& a1, const IPAddress& a2) {
  DCHECK_EQ(a1.size(), a2.size());
  for (size_t i = 0; i < a1.size(); ++i) {
    unsigned diff = a1.bytes()[i] ^ a2.bytes()[i];
    if (!diff)
      continue;
    for (unsigned j = 0; j < CHAR_BIT; ++j) {
      if (diff & (1 << (CHAR_BIT - 1)))
        return i * CHAR_BIT + j;
      diff <<= 1;
    }
    NOTREACHED();
  }
  return a1.size() * CHAR_BIT;
}

unsigned MaskPrefixLength(const IPAddress& mask) {
  std::vector<uint8_t> all_ones(mask.size(), 0xFF);
  return CommonPrefixLength(mask, IPAddress(all_ones));
}

}  // namespace net