/* SPDX-License-Identifier: GPL-3.0-or-later

 * Copyright © 2016-2018 The TokTok team.

 * Copyright © 2013 Tox project.

 */

/**

 * LAN discovery implementation.

 */

#include "LAN_discovery.h"

#include <stdlib.h>

#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)

// The mingw32/64 Windows library warns about including winsock2.h after

// windows.h even though with the above it's a valid thing to do. So, to make

// mingw32 headers happy, we include winsock2.h first.

#include <winsock2.h>

#include <windows.h>

#include <ws2tcpip.h>

#include <iphlpapi.h>

#endif /* WIN32 */

#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)

#include <netinet/in.h>

#include <sys/ioctl.h>

#include <sys/socket.h>

#include <sys/types.h>

#include <unistd.h>

#endif /* Linux/BSD */

#ifdef __linux__

#include <linux/if.h>

#endif /* Linux */

#if defined(__FreeBSD__) || defined(__DragonFly__)

#include <net/if.h>

#endif /* BSD */

#include "ccompat.h"

#include "crypto_core.h"

#include "network.h"

#define MAX_INTERFACES 16

struct Broadcast_Info {

    uint32_t count;

    IP ips[MAX_INTERFACES];

};

#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)

non_null()

static Broadcast_Info *fetch_broadcast_info(const Network *ns)

{

    Broadcast_Info *broadcast = (Broadcast_Info *)calloc(1, sizeof(Broadcast_Info));

    if (broadcast == nullptr) {

        return nullptr;

    }

    IP_ADAPTER_INFO *adapter_info = (IP_ADAPTER_INFO *)malloc(sizeof(IP_ADAPTER_INFO));

    if (adapter_info == nullptr) {

        free(broadcast);

        return nullptr;

    }

    unsigned long out_buf_len = sizeof(IP_ADAPTER_INFO);

    if (GetAdaptersInfo(adapter_info, &out_buf_len) == ERROR_BUFFER_OVERFLOW) {

        free(adapter_info);

        IP_ADAPTER_INFO *new_adapter_info = (IP_ADAPTER_INFO *)malloc(out_buf_len);

        if (new_adapter_info == nullptr) {

            free(broadcast);

            return nullptr;

        }

        adapter_info = new_adapter_info;

    }

    const int ret = GetAdaptersInfo(adapter_info, &out_buf_len);

    if (ret == NO_ERROR) {

        IP_ADAPTER_INFO *adapter = adapter_info;

        while (adapter != nullptr) {

            IP gateway = {0};

            IP subnet_mask = {0};

            if (addr_parse_ip(adapter->IpAddressList.IpMask.String, &subnet_mask)

                    && addr_parse_ip(adapter->GatewayList.IpAddress.String, &gateway)) {

                if (net_family_is_ipv4(gateway.family) && net_family_is_ipv4(subnet_mask.family)) {

                    IP *ip = &broadcast->ips[broadcast->count];

                    ip->family = net_family_ipv4();

                    const uint32_t gateway_ip = net_ntohl(gateway.ip.v4.uint32);

                    const uint32_t subnet_ip = net_ntohl(subnet_mask.ip.v4.uint32);

                    const uint32_t broadcast_ip = gateway_ip + ~subnet_ip - 1;

                    ip->ip.v4.uint32 = net_htonl(broadcast_ip);

                    ++broadcast->count;

                    if (broadcast->count >= MAX_INTERFACES) {

                        break;

                    }

                }

            }

            adapter = adapter->Next;

        }

    }

    if (adapter_info != nullptr) {

        free(adapter_info);

    }

    return broadcast;

}

#elif !defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && (defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__))

non_null()

static Broadcast_Info *fetch_broadcast_info(const Network *ns)

{

    Broadcast_Info *broadcast = (Broadcast_Info *)calloc(1, sizeof(Broadcast_Info));

    if (broadcast == nullptr) {

        return nullptr;

    }

    /* Not sure how many platforms this will run on,

     * so it's wrapped in `__linux__` for now.

     * Definitely won't work like this on Windows...

     */

    const Socket sock = net_socket(ns, net_family_ipv4(), TOX_SOCK_STREAM, 0);

    if (!sock_valid(sock)) {

        free(broadcast);

        return nullptr;

    }

    /* Configure ifconf for the ioctl call. */

    struct ifreq i_faces[MAX_INTERFACES] = {{0}};

    struct ifconf ifc;

    ifc.ifc_buf = (char *)i_faces;

    ifc.ifc_len = sizeof(i_faces);

    if (ioctl(sock.sock, SIOCGIFCONF, &ifc) < 0) {

        kill_sock(ns, sock);

        free(broadcast);

        return nullptr;

    }

    /* `ifc.ifc_len` is set by the `ioctl()` to the actual length used.

     * On usage of the complete array the call should be repeated with

     * a larger array, not done (640kB and 16 interfaces shall be

     * enough, for everybody!)

     */

    const int n = ifc.ifc_len / sizeof(struct ifreq);

    for (int i = 0; i < n; ++i) {

        /* there are interfaces with are incapable of broadcast */

        if (ioctl(sock.sock, SIOCGIFBRDADDR, &i_faces[i]) < 0) {

            continue;

        }

        /* moot check: only AF_INET returned (backwards compat.) */

        if (i_faces[i].ifr_broadaddr.sa_family != AF_INET) {

            continue;

        }

        const struct sockaddr_in *sock4 = (const struct sockaddr_in *)(void *)&i_faces[i].ifr_broadaddr;

        if (broadcast->count >= MAX_INTERFACES) {

            break;

        }

        IP *ip = &broadcast->ips[broadcast->count];

        ip->family = net_family_ipv4();

        ip->ip.v4.uint32 = sock4->sin_addr.s_addr;

        if (ip->ip.v4.uint32 == 0) {

            continue;

        }

        ++broadcast->count;

    }

    kill_sock(ns, sock);

    return broadcast;

}

#else // TODO(irungentoo): Other platforms?

non_null()

static Broadcast_Info *fetch_broadcast_info(const Network *ns)

{

    return (Broadcast_Info *)calloc(1, sizeof(Broadcast_Info));

}

#endif /* platforms */

/** @brief Send packet to all IPv4 broadcast addresses

 *

 * @retval true if sent to at least one broadcast target.

 * @retval false on failure to find any valid broadcast target.

 */

non_null()

static bool send_broadcasts(const Networking_Core *net, const Broadcast_Info *broadcast, uint16_t port,

                            const uint8_t *data, uint16_t length)

{

    if (broadcast->count == 0) {

        return false;

    }

    for (uint32_t i = 0; i < broadcast->count; ++i) {

        IP_Port ip_port;

        ip_port.ip = broadcast->ips[i];

        ip_port.port = port;

        sendpacket(net, &ip_port, data, length);

    }

    return true;

}

/** Return the broadcast ip. */

static IP broadcast_ip(Family family_socket, Family family_broadcast)

{

    IP ip;

    ip_reset(&ip);

    if (net_family_is_ipv6(family_socket)) {

        if (net_family_is_ipv6(family_broadcast)) {

            ip.family = net_family_ipv6();

            /* `FF02::1` is - according to RFC 4291 - multicast all-nodes link-local */

            /* `FE80::*:` MUST be exact, for that we would need to look over all

             * interfaces and check in which status they are */

            ip.ip.v6.uint8[ 0] = 0xFF;

            ip.ip.v6.uint8[ 1] = 0x02;

            ip.ip.v6.uint8[15] = 0x01;

        } else if (net_family_is_ipv4(family_broadcast)) {

            ip.family = net_family_ipv6();

            ip.ip.v6 = get_ip6_broadcast();

        }

    } else if (net_family_is_ipv4(family_socket) && net_family_is_ipv4(family_broadcast)) {

        ip.family = net_family_ipv4();

        ip.ip.v4 = get_ip4_broadcast();

    }

    return ip;

}

non_null()

static bool ip4_is_local(const IP4 *ip4)

{

    /* Loopback. */

    return ip4->uint8[0] == 127;

}

/**

 * Is IP a local ip or not.

 */

bool ip_is_local(const IP *ip)

{

    if (net_family_is_ipv4(ip->family)) {

        return ip4_is_local(&ip->ip.v4);

    }

    /* embedded IPv4-in-IPv6 */

    if (ipv6_ipv4_in_v6(&ip->ip.v6)) {

        IP4 ip4;

        ip4.uint32 = ip->ip.v6.uint32[3];

        return ip4_is_local(&ip4);

    }

    /* localhost in IPv6 (::1) */

    return ip->ip.v6.uint64[0] == 0 && ip->ip.v6.uint32[2] == 0 && ip->ip.v6.uint32[3] == net_htonl(1);

}

non_null()

static bool ip4_is_lan(const IP4 *ip4)

{

    /* 10.0.0.0 to 10.255.255.255 range. */

    if (ip4->uint8[0] == 10) {

        return true;

    }

    /* 172.16.0.0 to 172.31.255.255 range. */

    if (ip4->uint8[0] == 172 && ip4->uint8[1] >= 16 && ip4->uint8[1] <= 31) {

        return true;

    }

    /* 192.168.0.0 to 192.168.255.255 range. */

    if (ip4->uint8[0] == 192 && ip4->uint8[1] == 168) {

        return true;

    }

    /* 169.254.1.0 to 169.254.254.255 range. */

    if (ip4->uint8[0] == 169 && ip4->uint8[1] == 254 && ip4->uint8[2] != 0

            && ip4->uint8[2] != 255) {

        return true;

    }

    /* RFC 6598: 100.64.0.0 to 100.127.255.255 (100.64.0.0/10)

     * (shared address space to stack another layer of NAT) */

    return (ip4->uint8[0] == 100) && ((ip4->uint8[1] & 0xC0) == 0x40);

}

bool ip_is_lan(const IP *ip)

{

    if (ip_is_local(ip)) {

        return true;

    }

    if (net_family_is_ipv4(ip->family)) {

        return ip4_is_lan(&ip->ip.v4);

    }

    if (net_family_is_ipv6(ip->family)) {

        /* autogenerated for each interface: `FE80::*` (up to `FEBF::*`)

         * `FF02::1` is - according to RFC 4291 - multicast all-nodes link-local */

        if (((ip->ip.v6.uint8[0] == 0xFF) && (ip->ip.v6.uint8[1] < 3) && (ip->ip.v6.uint8[15] == 1)) ||

                ((ip->ip.v6.uint8[0] == 0xFE) && ((ip->ip.v6.uint8[1] & 0xC0) == 0x80))) {

            return true;

        }

        /* embedded IPv4-in-IPv6 */

        if (ipv6_ipv4_in_v6(&ip->ip.v6)) {

            IP4 ip4;

            ip4.uint32 = ip->ip.v6.uint32[3];

            return ip4_is_lan(&ip4);

        }

    }

    return false;

}

bool lan_discovery_send(const Networking_Core *net, const Broadcast_Info *broadcast, const uint8_t *dht_pk,

                        uint16_t port)

{

    if (broadcast == nullptr) {

        return false;

    }

    uint8_t data[CRYPTO_PUBLIC_KEY_SIZE + 1];

    data[0] = NET_PACKET_LAN_DISCOVERY;

    pk_copy(data + 1, dht_pk);

    send_broadcasts(net, broadcast, port, data, 1 + CRYPTO_PUBLIC_KEY_SIZE);

    bool res = false;

    IP_Port ip_port;

    ip_port.port = port;

    /* IPv6 multicast */

    if (net_family_is_ipv6(net_family(net))) {

        ip_port.ip = broadcast_ip(net_family_ipv6(), net_family_ipv6());

        if (ip_isset(&ip_port.ip) && sendpacket(net, &ip_port, data, 1 + CRYPTO_PUBLIC_KEY_SIZE) > 0) {

            res = true;

        }

    }

    /* IPv4 broadcast (has to be IPv4-in-IPv6 mapping if socket is IPv6 */

    ip_port.ip = broadcast_ip(net_family(net), net_family_ipv4());

    if (ip_isset(&ip_port.ip) && sendpacket(net, &ip_port, data, 1 + CRYPTO_PUBLIC_KEY_SIZE) > 0) {

        res = true;

    }

    return res;

}

Broadcast_Info *lan_discovery_init(const Network *ns)

{

    return fetch_broadcast_info(ns);

}

void lan_discovery_kill(Broadcast_Info *broadcast)

{

    free(broadcast);

}