/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

/* DEBUG: section 42    ICMP Pinger program */

//#define SQUID_HELPER 1

#include "squid.h"

#if USE_ICMP

#include "debug/Stream.h"
#include "Icmp6.h"
#include "IcmpPinger.h"
#include "time/gadgets.h"

// Some system headers are only neeed internally here.
// They should not be included via the header.

#if HAVE_NETINET_IP6_H
#include <netinet/ip6.h>
#endif

// Icmp6 OP-Codes
// see http://www.iana.org/assignments/icmpv6-parameters
static const char *
IcmpPacketType(uint8_t v)
{
    // NP: LowPktStr is for codes 0-127
    static const char *icmp6LowPktStr[] = {
        "ICMPv6 0",         // 0
        "Destination Unreachable",  // 1 - RFC2463
        "Packet Too Big",       // 2 - RFC2463
        "Time Exceeded",        // 3 - RFC2463
        "Parameter Problem",        // 4 - RFC2463
    };

    // low codes 1-4 registered
    if (0 < v && v < 5)
        return icmp6LowPktStr[(int)(v&0x7f)];

    // NP: HighPktStr is for codes 128-255
    static const char *icmp6HighPktStr[] = {
        "Echo Request",                 // 128 - RFC2463
        "Echo Reply",                   // 129 - RFC2463
        "Multicast Listener Query",         // 130 - RFC2710
        "Multicast Listener Report",            // 131 - RFC2710
        "Multicast Listener Done",          // 132 - RFC2710
        "Router Solicitation",              // 133 - RFC4861
        "Router Advertisement",             // 134 - RFC4861
        "Neighbor Solicitation",            // 135 - RFC4861
        "Neighbor Advertisement",           // 136 - RFC4861
        "Redirect Message",             // 137 - RFC4861
        "Router Renumbering",               // 138 - Crawford
        "ICMP Node Information Query",          // 139 - RFC4620
        "ICMP Node Information Response",       // 140 - RFC4620
        "Inverse Neighbor Discovery Solicitation",  // 141 - RFC3122
        "Inverse Neighbor Discovery Advertisement", // 142 - RFC3122
        "Version 2 Multicast Listener Report",      // 143 - RFC3810
        "Home Agent Address Discovery Request",     // 144 - RFC3775
        "Home Agent Address Discovery Reply",       // 145 - RFC3775
        "Mobile Prefix Solicitation",           // 146 - RFC3775
        "Mobile Prefix Advertisement",          // 147 - RFC3775
        "Certification Path Solicitation",      // 148 - RFC3971
        "Certification Path Advertisement",     // 149 - RFC3971
        "ICMP Experimental (150)",          // 150 - RFC4065
        "Multicast Router Advertisement",       // 151 - RFC4286
        "Multicast Router Solicitation",        // 152 - RFC4286
        "Multicast Router Termination",         // 153 - [RFC4286]
    };

    // high codes 127-153 registered
    if (127 < v && v < 154)
        return icmp6HighPktStr[(int)(v&0x7f)];

    // give all others a generic display
    static char buf[50];
    snprintf(buf, sizeof(buf), "ICMPv6 %u", v);
    return buf;
}

Icmp6::Icmp6() : Icmp()
{
    ; // nothing new.
}

Icmp6::~Icmp6()
{
    Close();
}

int
Icmp6::Open(void)
{
    icmp_sock = socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6);

    if (icmp_sock < 0) {
        int xerrno = errno;
        debugs(50, DBG_CRITICAL, MYNAME << " icmp_sock: " << xstrerr(xerrno));
        return -1;
    }

    icmp_ident = getpid() & 0xffff;
    debugs(42, DBG_IMPORTANT, "ICMPv6 socket opened");

    return icmp_sock;
}

/**
 * Generates an RFC 4443 Icmp6 ECHO Packet and sends into the network.
 */
void
Icmp6::SendEcho(Ip::Address &to, int opcode, const char *payload, int len)
{
    int x;
    LOCAL_ARRAY(char, pkt, MAX_PKT6_SZ);
    struct icmp6_hdr *icmp = nullptr;
    icmpEchoData *echo = nullptr;
    struct addrinfo *S = nullptr;
    size_t icmp6_pktsize = 0;

    static_assert(sizeof(*icmp) + sizeof(*echo) <= sizeof(pkt), "our custom ICMPv6 Echo payload fits the packet buffer");

    memset(pkt, '\0', MAX_PKT6_SZ);
    icmp = (struct icmp6_hdr *)pkt;

    /*
     * cevans - beware signed/unsigned issues in untrusted data from
     * the network!!
     */
    if (len < 0) {
        len = 0;
    }

    // Construct Icmp6 ECHO header
    icmp->icmp6_type = ICMP6_ECHO_REQUEST;
    icmp->icmp6_code = 0;
    icmp->icmp6_cksum = 0;
    icmp->icmp6_id = icmp_ident;
    icmp->icmp6_seq = (unsigned short) icmp_pkts_sent;
    ++icmp_pkts_sent;

    icmp6_pktsize = sizeof(struct icmp6_hdr);

    // Fill Icmp6 ECHO data content
    echo = reinterpret_cast<icmpEchoData *>(reinterpret_cast<char *>(pkt) + sizeof(*icmp));
    echo->opcode = (unsigned char) opcode;
    memcpy(&echo->tv, &current_time, sizeof(struct timeval));

    icmp6_pktsize += sizeof(struct timeval) + sizeof(char);

    if (payload) {
        if (len > MAX_PAYLOAD)
            len = MAX_PAYLOAD;

        memcpy(echo->payload, payload, len);

        icmp6_pktsize += len;
    }

    icmp->icmp6_cksum = CheckSum((unsigned short *) icmp, icmp6_pktsize);

    to.getAddrInfo(S);
    ((sockaddr_in6*)S->ai_addr)->sin6_port = 0;

    assert(icmp6_pktsize <= MAX_PKT6_SZ);

    debugs(42, 5, "Send Icmp6 packet to " << to << ".");

    x = sendto(icmp_sock,
               (const void *) pkt,
               icmp6_pktsize,
               0,
               S->ai_addr,
               S->ai_addrlen);

    if (x < 0) {
        int xerrno = errno;
        debugs(42, DBG_IMPORTANT, MYNAME << "ERROR: sending to ICMPv6 packet to " << to << ": " << xstrerr(xerrno));
    }
    debugs(42,9, "x=" << x);

    Log(to, 0, nullptr, 0, 0);
    Ip::Address::FreeAddr(S);
}

/**
 * Reads an RFC 4443 Icmp6 ECHO-REPLY Packet from the network.
 */
void
Icmp6::Recv(void)
{
    int n;
    struct addrinfo *from = nullptr;
//    struct ip6_hdr *ip = nullptr;
    static char *pkt = nullptr;
    struct icmp6_hdr *icmp6header = nullptr;
    icmpEchoData *echo = nullptr;
    struct timeval now;
    static pingerReplyData preply;

    if (icmp_sock < 0) {
        debugs(42, DBG_CRITICAL, "dropping ICMPv6 read. No socket!?");
        return;
    }

    if (pkt == nullptr) {
        pkt = (char *)xmalloc(MAX_PKT6_SZ);
    }

    Ip::Address::InitAddr(from);

    n = recvfrom(icmp_sock,
                 (void *)pkt,
                 MAX_PKT6_SZ,
                 0,
                 from->ai_addr,
                 &from->ai_addrlen);

    if (n <= 0) {
        debugs(42, DBG_CRITICAL, "ERROR: when calling recvfrom() on ICMPv6 socket.");
        Ip::Address::FreeAddr(from);
        return;
    }

    preply.from = *from;

#if GETTIMEOFDAY_NO_TZP

    gettimeofday(&now);

#else

    gettimeofday(&now, nullptr);

#endif

    debugs(42, 8, n << " bytes from " << preply.from);

// XXX: The IPv6 Header (ip6_hdr) is not available directly
//
// TTL still has to come from the IP header somewhere.
//  still need to strip and process it properly.
//  probably have to rely on RTT as given by timestamp in data sent and current.
    /* IPv6 Header Structures (linux)
    struct ip6_hdr

    // fields (via simple define)
    #define ip6_vfc     // N.A
    #define ip6_flow    // N/A
    #define ip6_plen    // payload length.
    #define ip6_nxt     // expect to be type 0x3a - ICMPv6
    #define ip6_hlim    // MAX hops  (always 64, but no guarantee)
    #define ip6_hops    // HOPS!!!  (can it be true??)

        ip = (struct ip6_hdr *) pkt;
        //  += sizeof(ip6_hdr);

    debugs(42, DBG_CRITICAL, "ip6_nxt=" << ip->ip6_nxt <<
            ", ip6_plen=" << ip->ip6_plen <<
            ", ip6_hlim=" << ip->ip6_hlim <<
            ", ip6_hops=" << ip->ip6_hops   <<
            " ::: 40 == sizef(ip6_hdr) == " << sizeof(ip6_hdr)
    );
    */

    icmp6header = (struct icmp6_hdr *) pkt;

    if (icmp6header->icmp6_type != ICMP6_ECHO_REPLY) {

        switch (icmp6header->icmp6_type) {
        case 134:
        case 135:
        case 136:
            /* ignore Router/Neighbour Advertisements */
            break;

        default:
            debugs(42, 8, preply.from << " said: " << icmp6header->icmp6_type << "/" << (int)icmp6header->icmp6_code << " " <<
                   IcmpPacketType(icmp6header->icmp6_type));
        }
        Ip::Address::FreeAddr(from);
        return;
    }

    if (icmp6header->icmp6_id != icmp_ident) {
        debugs(42, 8, "dropping Icmp6 read. IDENT check failed. ident=='" << icmp_ident << "'=='" << icmp6header->icmp6_id << "'");
        Ip::Address::FreeAddr(from);
        return;
    }

    echo = (icmpEchoData *) (pkt + sizeof(icmp6_hdr));

    preply.opcode = echo->opcode;

    struct timeval tv;
    memcpy(&tv, &echo->tv, sizeof(struct timeval));
    preply.rtt = tvSubMsec(tv, now);

    /*
     * Without access to the IPv6-Hops header we must rely on the total RTT
     * and could calculate the hops from that, but it produces some weird value mappings using ipHops
     * for now everything is 1 v6 hop away with variant RTT
     * WANT:    preply.hops = ip->ip6_hops; // ipHops(ip->ip_hops);
     */
    preply.hops = 1;

    preply.psize = n - /* sizeof(ip6_hdr) - */ sizeof(icmp6_hdr) - (sizeof(icmpEchoData) - MAX_PKT6_SZ);

    /* Ensure the response packet has safe payload size */
    if ( preply.psize > (unsigned short) MAX_PKT6_SZ) {
        preply.psize = MAX_PKT6_SZ;
    } else if ( preply.psize < (unsigned short)0) {
        preply.psize = 0;
    }

    Log(preply.from,
        icmp6header->icmp6_type,
        IcmpPacketType(icmp6header->icmp6_type),
        preply.rtt,
        preply.hops);

    /* send results of the lookup back to squid.*/
    control.SendResult(preply, (sizeof(pingerReplyData) - PINGER_PAYLOAD_SZ + preply.psize) );
    Ip::Address::FreeAddr(from);
}

#endif /* USE_ICMP */