src/lib/dnssd/IPAddressSorter.h

/*
 *
 *    Copyright (c) 2022 Project CHIP Authors
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
#pragma once

#include <inet/IPAddress.h>
#include <lib/support/Span.h>

namespace chip {
namespace Dnssd {
namespace IPAddressSorter {

// IP addess "suitability"
//   - Larger value means "more suitable"
//   - Enum ordered ascending for easier read. Note however that order of
//     checks MUST match in ScoreIpAddress below.
enum class IpScore : unsigned
{
    kInvalid = 0, // No address available

    // "Other" IPv6 include:
    //   - invalid addresses (have seen router bugs during interop testing)
    //   - embedded IPv4 (::/80)
    kOtherIpv6 = 1,
    kIpv4      = 2, // Not Matter SPEC, so low priority
#ifdef __APPLE__
    kUniqueLocal                   = 3, // ULA. Thread devices use this
    kGlobalUnicast                 = 4, // Maybe routable, not local subnet
    kUniqueLocalWithSharedPrefix   = 5, // Prefix seems to match a local interface
    kGlobalUnicastWithSharedPrefix = 6, // Prefix seems to match a local interface
    kLinkLocal                     = 7, // Valid only on an interface
#else
    kLinkLocal                     = 3, // Valid only on an interface
    kUniqueLocal                   = 4, // ULA. Thread devices use this
    kGlobalUnicast                 = 5, // Maybe routable, not local subnet
    kUniqueLocalWithSharedPrefix   = 6, // Prefix seems to match a local interface
    kGlobalUnicastWithSharedPrefix = 7, // Prefix seems to match a local interface
#endif // __APPLE__
};

void Sort(Inet::IPAddress * addresses, size_t count, Inet::InterfaceId interfaceId);

void Sort(const Span<Inet::IPAddress> & addresses, Inet::InterfaceId interfaceId);

/**
 * Gives a score for an IP address, generally related to "how good" the address
 * is and how likely it is for it to be reachable.
 */
IpScore ScoreIpAddress(const Inet::IPAddress & ip, Inet::InterfaceId interfaceId);

} // namespace IPAddressSorter
} // namespace Dnssd
} // namespace chip