/* bzflag
 * Copyright (c) 1993-2021 Tim Riker
 *
 * This package is free software;  you can redistribute it and/or
 * modify it under the terms of the license found in the file
 * named COPYING that should have accompanied this file.
 *
 * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

// bzflag common header
#include "common.h"

// interface header
#include "IPUtils.h"

#ifdef _WIN32
#include <ws2tcpip.h>
#else
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
//#include <arpa/inet.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <algorithm>

int IPUtils::stringToAddr(const char *addr, struct sockaddr_storage *ss) {
    struct addrinfo hints, *res;
    int status;
    char port_buffer[6] = "\0";

    // Set up the hints for getaddrinfo
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV;

    // Attempt to convert the string representation
    if ((status = getaddrinfo(addr, port_buffer, &hints, &res)) != 0)
        return status;

    // Copy the result back into our sockaddr_storage
    memcpy(ss, res->ai_addr, res->ai_addrlen);

    // Free the memory from the result
    free(res);

    return status;
}

int IPUtils::addrToString(struct sockaddr_storage ss, char *addr, sa_family_t *family) {
    char host[INET6_ADDRSTRLEN];
    int status;

    // Attempt to
    if ((status = getnameinfo((struct sockaddr *)&ss, (ss.ss_family == AF_INET)?sizeof(struct sockaddr_in):sizeof(struct sockaddr_in6), host, sizeof host, nullptr, 0, NI_NUMERICHOST)) != 0)
        return status;

    // Copy the result back
    memcpy(addr, host, sizeof host);
    *family = ss.ss_family;

    return status;
}

bool IPUtils::networkContainsIP(struct sockaddr_storage networkID, unsigned char cidr, struct sockaddr_storage addr)
{
    // If these aren't even the same address family, it can't contain the IP
    if (networkID.ss_family != addr.ss_family)
        return false;

    if (cidr == 0)
        return true;

    // Check if the network bits match
    if (addr.ss_family == AF_INET)
    {
        if (cidr > 32)
            return false;

        // Compare the network bits
        return (htonl((*(struct sockaddr_in*)&networkID).sin_addr.s_addr) >> (32-cidr)) == (htonl((*(struct sockaddr_in*)&addr).sin_addr.s_addr) >> (32-cidr));
    }
    else if (addr.ss_family == AF_INET6)
    {
        if (cidr > 128)
            return false;

        for (int i = 0; i < 16; ++i)
        {
            unsigned char networkBits = std::max(0, std::min(8, cidr-i*8));
            if (networkBits > 0 && ((*(struct sockaddr_in6*)&networkID).sin6_addr.s6_addr[i] & (255 >> (8-networkBits))) != ((*(struct sockaddr_in6*)&addr).sin6_addr.s6_addr[i] & (255 >> (8-networkBits))))
                return false;
        }

        return true;
    }

    return false;
}

bool IPUtils::networkID(struct sockaddr_storage addr, unsigned char cidr, struct sockaddr_storage *networkID)
{
    if (addr.ss_family == AF_INET)
    {
        // CIDR for IPv4 is limited to 32 bits
        if (cidr > 32)
            return false;

        // Zero out the host bits
        (*(struct sockaddr_in*)&addr).sin_addr.s_addr = (*(struct sockaddr_in*)&addr).sin_addr.s_addr & ntohl(4294967295 >> (32-cidr) << (32-cidr));
    }
    else if (addr.ss_family == AF_INET6)
    {
        // CIDR for IPv6 is limited to 128 bits
        if (cidr > 128)
            return false;

        // Zero out the host bits
        for (int i = 0; i < 16; ++i)
        {
            unsigned char networkBits = std::max(0, std::min(8, cidr-i*8));
            if (networkBits < 8)
                (*(struct sockaddr_in6*)&addr).sin6_addr.s6_addr[i] = (*(struct sockaddr_in6*)&addr).sin6_addr.s6_addr[i] & (255 >> (8-networkBits) << (8-networkBits));
        }
    }
    else
    {
        return false;
    }

    memcpy(networkID, &addr, sizeof(addr));
    return true;
}