lokinet/llarp/net/net_bits.hpp

#pragma once

#include "ip.hpp"
#include "net_int.hpp"

namespace llarp
{
    /// get a netmask with the higest numset bits set
    constexpr huint128_t _netmask_ipv6_bits(uint32_t numset)
    {
        return (128 - numset) ? (huint128_t{1} << numset) | _netmask_ipv6_bits(numset + 1) : huint128_t{0};
    }

    constexpr huint128_t netmask_ipv6_bits(uint32_t numset)
    {
        return _netmask_ipv6_bits(128 - numset);
    }

    /// get a netmask with the higest numset bits set
    constexpr uint32_t _netmask_ipv4_bits(uint32_t numset)
    {
        return (32 - numset) ? (1 << numset) | _netmask_ipv4_bits(numset + 1) : 0;
    }

    /// get a netmask given some /N range
    constexpr huint32_t netmask_ipv4_bits(uint32_t num)
    {
        return huint32_t{_netmask_ipv4_bits(32 - num)};
    }

    constexpr huint32_t ipaddr_ipv4_bits(uint32_t a, uint32_t b, uint32_t c, uint32_t d)
    {
        return huint32_t{(d) | (c << 8) | (b << 16) | (a << 24)};
    }

    // IPv4 mapped address live at ::ffff:0:0/96
    constexpr std::array<uint8_t, 12> ipv4_map_prefix{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff};

    namespace net
    {
        inline auto ipaddr_netmask_bits(uint32_t bits, int af)
        {
            if (af == AF_INET6)
                return netmask_ipv6_bits(bits);
            return ExpandV4(netmask_ipv4_bits(bits));
        };
    }  // namespace net
}  // namespace llarp