chromium/components/feedback/redaction_tool/ip_address.h

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

// This is a copy of net/base/ip_address.h circa 2023. It should be used only by
// components/feedback/redaction_tool/.
// We need a copy because the components/feedback/redaction_tool source code is
// shared into ChromeOS and needs to have no dependencies outside of base/.

#ifndef COMPONENTS_FEEDBACK_REDACTION_TOOL_IP_ADDRESS_H_
#define COMPONENTS_FEEDBACK_REDACTION_TOOL_IP_ADDRESS_H_

#include <stddef.h>
#include <stdint.h>

#include <algorithm>
#include <array>
#include <string>
#include <string_view>
#include <vector>

#include "base/check_op.h"
#include "base/values.h"

namespace redaction_internal {

// Helper class to represent the sequence of bytes in an IP address.
// A vector<uint8_t> would be simpler but incurs heap allocation, so
// IPAddressBytes uses a fixed size array.
class IPAddressBytes { … };

class IPAddress { … };

IPAddressList;

// Returns the canonical string representation of an IP address along with its
// port. For example: "192.168.0.1:99" or "[::1]:80".
std::string IPAddressToStringWithPort(const IPAddress& address, uint16_t port);

// Returns the address as a sequence of bytes in network-byte-order.
std::string IPAddressToPackedString(const IPAddress& address);

// Converts an IPv4 address to an IPv4-mapped IPv6 address.
// For example 192.168.0.1 would be converted to ::ffff:192.168.0.1.
IPAddress ConvertIPv4ToIPv4MappedIPv6(const IPAddress& address);

// Converts an IPv4-mapped IPv6 address to IPv4 address. Should only be called
// on IPv4-mapped IPv6 addresses.
IPAddress ConvertIPv4MappedIPv6ToIPv4(const IPAddress& address);

// Compares an IP address to see if it falls within the specified IP block.
// Returns true if it does, false otherwise.
//
// The IP block is given by (|ip_prefix|, |prefix_length_in_bits|) -- any
// IP address whose |prefix_length_in_bits| most significant bits match
// |ip_prefix| will be matched.
//
// In cases when an IPv4 address is being compared to an IPv6 address prefix
// and vice versa, the IPv4 addresses will be converted to IPv4-mapped
// (IPv6) addresses.
bool IPAddressMatchesPrefix(const IPAddress& ip_address,
                            const IPAddress& ip_prefix,
                            size_t prefix_length_in_bits);

// Checks whether |address| starts with |prefix|. This provides similar
// functionality as IPAddressMatchesPrefix() but doesn't perform automatic IPv4
// to IPv4MappedIPv6 conversions and only checks against full bytes.
template <size_t N>
bool IPAddressStartsWith(const IPAddress& address, const uint8_t (&prefix)[N]) { … }

// According to RFC6052 Section 2.2 IPv4-Embedded IPv6 Address Format.
// https://www.rfc-editor.org/rfc/rfc6052#section-2.2
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
// |PL| 0-------------32--40--48--56--64--72--80--88--96--104---------|
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
// |32|     prefix    |v4(32)         | u | suffix                    |
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
// |40|     prefix        |v4(24)     | u |(8)| suffix                |
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
// |48|     prefix            |v4(16) | u | (16)  | suffix            |
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
// |56|     prefix                |(8)| u |  v4(24)   | suffix        |
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
// |64|     prefix                    | u |   v4(32)      | suffix    |
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
// |96|     prefix                                    |    v4(32)     |
// +--+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
//
// The NAT64/DNS64 translation prefixes has one of the following lengths.
enum class Dns64PrefixLength { … };

// Extracts the NAT64 translation prefix from the IPv6 address using the well
// known address ipv4only.arpa 192.0.0.170 and 192.0.0.171.
// Returns prefix length on success, or Dns64PrefixLength::kInvalid on failure
// (when the ipv4only.arpa IPv4 address is not found)
Dns64PrefixLength ExtractPref64FromIpv4onlyArpaAAAA(const IPAddress& address);

// Converts an IPv4 address to an IPv4-embedded IPv6 address using the given
// prefix. For example 192.168.0.1 and 64:ff9b::/96 would be converted to
// 64:ff9b::192.168.0.1
// Returns converted IPv6 address when prefix_length is not
// Dns64PrefixLength::kInvalid, and returns the original IPv4 address when
// prefix_length is Dns64PrefixLength::kInvalid.
IPAddress ConvertIPv4ToIPv4EmbeddedIPv6(const IPAddress& ipv4_address,
                                        const IPAddress& ipv6_address,
                                        Dns64PrefixLength prefix_length);

}  // namespace redaction_internal

#endif  // COMPONENTS_FEEDBACK_REDACTION_TOOL_IP_ADDRESS_H_