Icmp4.cc

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/*
 * Copyright (C) 1996-2025 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 "base/Assure.h"
#include "compat/socket.h"
#include "debug/Stream.h"
#include "Icmp4.h"
#include "IcmpPinger.h"
#include "time/gadgets.h"
 
static const char *
IcmpPacketType(uint8_t v)
{
    static const char *icmpPktStr[] = {
        "Echo Reply",
        "ICMP 1",
        "ICMP 2",
        "Destination Unreachable",
        "Source Quench",
        "Redirect",
        "ICMP 6",
        "ICMP 7",
        "Echo",
        "ICMP 9",
        "ICMP 10",
        "Time Exceeded",
        "Parameter Problem",
        "Timestamp",
        "Timestamp Reply",
        "Info Request",
        "Info Reply",
        "Out of Range Type"
    };
 
    if (v > 17) {
        static char buf[50];
        snprintf(buf, sizeof(buf), "ICMP %u (invalid)", v);
        return buf;
    }
 
    return icmpPktStr[v];
}
 
Icmp4::Icmp4() : Icmp()
{
    ;
}
 
Icmp4::~Icmp4()
{
    Close();
}
 
int
Icmp4::Open(void)
{
    icmp_sock = xsocket(PF_INET, SOCK_RAW, IPPROTO_ICMP);
 
    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, "ICMP socket opened.");
 
    return icmp_sock;
}
 
void
Icmp4::SendEcho(Ip::Address &to, int opcode, const char *payload, int len)
{
    int x;
    LOCAL_ARRAY(char, pkt, MAX_PKT4_SZ);
 
    struct icmphdr *icmp = nullptr;
    icmpEchoData *echo;
    size_t icmp_pktsize = sizeof(struct icmphdr);
    struct addrinfo *S = nullptr;
 
    static_assert(sizeof(*icmp) + sizeof(*echo) <= sizeof(pkt), "our custom ICMPv4 Echo payload fits the packet buffer");
 
    memset(pkt, '\0', MAX_PKT4_SZ);
 
    icmp = (struct icmphdr *) (void *) pkt;
 
    /*
     * cevans - beware signed/unsigned issues in untrusted data from
     * the network!!
     */
    if (len < 0) {
        len = 0;
    }
 
    // Construct ICMP packet header
    icmp->icmp_type = ICMP_ECHO;
    icmp->icmp_code = 0;
    icmp->icmp_cksum = 0;
    icmp->icmp_id = icmp_ident;
    icmp->icmp_seq = (unsigned short) icmp_pkts_sent;
    ++icmp_pkts_sent;
 
    // Construct ICMP packet 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));
 
    icmp_pktsize += sizeof(icmpEchoData) - MAX_PAYLOAD;
 
    if (payload) {
        if (len > MAX_PAYLOAD)
            len = MAX_PAYLOAD;
 
        memcpy(echo->payload, payload, len);
 
        icmp_pktsize += len;
    }
 
    icmp->icmp_cksum = CheckSum((unsigned short *) icmp, icmp_pktsize);
 
    to.getAddrInfo(S, AF_INET);
    Assure(S);
 
    ((sockaddr_in*)S->ai_addr)->sin_port = 0;
    assert(icmp_pktsize <= MAX_PKT4_SZ);
 
    debugs(42, 5, "Send ICMP packet to " << to << ".");
 
    x = xsendto(icmp_sock,
                pkt,
                icmp_pktsize,
                0,
                S->ai_addr,
                S->ai_addrlen);
 
    if (x < 0) {
        int xerrno = errno;
        debugs(42, DBG_IMPORTANT, "ERROR: sending ICMP packet to " << to << ": " << xstrerr(xerrno));
    }
 
    Log(to, ' ', "", 0, 0);
    Ip::Address::FreeAddr(S);
}
 
void
Icmp4::Recv(void)
{
    int n;
    struct addrinfo *from = nullptr;
    int iphdrlen = sizeof(iphdr);
    struct iphdr *ip = nullptr;
    struct icmphdr *icmp = nullptr;
    static char *pkt = nullptr;
    struct timeval now;
    icmpEchoData *echo;
    static pingerReplyData preply;
 
    if (icmp_sock < 0) {
        debugs(42, DBG_CRITICAL, "No socket! Recv() should not be called.");
        return;
    }
 
    if (pkt == nullptr)
        pkt = (char *)xmalloc(MAX_PKT4_SZ);
 
    Ip::Address::InitAddr(from);
    n = xrecvfrom(icmp_sock,
                  pkt,
                  MAX_PKT4_SZ,
                  0,
                  from->ai_addr,
                  &from->ai_addrlen);
 
    if (n <= 0) {
        debugs(42, DBG_CRITICAL, "ERROR: when calling recvfrom() on ICMP 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);
 
    ip = (struct iphdr *) (void *) pkt;
    if (n < static_cast<int>(sizeof(*ip))) {
        debugs(42, 2, "short packet: only " << n << " bytes; expecting at least " << sizeof(*ip) << "-byte IP header");
        Ip::Address::FreeAddr(from);
        return;
    }
 
#if HAVE_STRUCT_IPHDR_IP_HL
 
    iphdrlen = ip->ip_hl << 2;
 
#else /* HAVE_STRUCT_IPHDR_IP_HL */
#if WORDS_BIGENDIAN
 
    iphdrlen = (ip->ip_vhl >> 4) << 2;
 
#else
 
    iphdrlen = (ip->ip_vhl & 0xF) << 2;
 
#endif
#endif /* HAVE_STRUCT_IPHDR_IP_HL */
 
    if (iphdrlen < 20 || n < iphdrlen) {
        debugs(42, 2, "bogus IP header length " << iphdrlen << " in " << n << "-byte packet");
        Ip::Address::FreeAddr(from);
        return;
    }
    icmp = (struct icmphdr *) (void *) (pkt + iphdrlen);
    const int icmpAvail = n - iphdrlen;
    if (icmpAvail < static_cast<int>(sizeof(*icmp))) {
        debugs(42, 2, "short ICMP header: only " << icmpAvail << " bytes available; expecting at least " << sizeof(*icmp));
        Ip::Address::FreeAddr(from);
        return;
    }
 
    if (icmp->icmp_type != ICMP_ECHOREPLY) {
        Ip::Address::FreeAddr(from);
        return;
    }
 
    if (icmp->icmp_id != icmp_ident) {
        Ip::Address::FreeAddr(from);
        return;
    }
 
    echo = (icmpEchoData *) (void *) (icmp + 1);
 
    const auto echoHdr = static_cast<int>(sizeof(icmpEchoData) - MAX_PAYLOAD);
    const auto icmpDataLen = icmpAvail - sizeof(*icmp);
    if (icmpDataLen < echoHdr) { // do not read past end of the packet
        debugs(42, 2, "short ICMP echo data: " << icmpDataLen << " bytes; expecting " << echoHdr);
        Ip::Address::FreeAddr(from);
        return;
    }
 
    preply.opcode = echo->opcode;
 
    preply.hops = ipHops(ip->ip_ttl);
 
    struct timeval tv;
    memcpy(&tv, &echo->tv, sizeof(struct timeval));
    preply.rtt = tvSubMsec(tv, now);
 
    // Payload length = (ICMP total data) - (opcode + timeval)
    preply.psize = icmpDataLen - echoHdr;
    if (preply.psize > MAX_PAYLOAD)
        preply.psize = MAX_PAYLOAD;
 
    if (preply.psize < 0) {
        debugs(42, DBG_CRITICAL, "ERROR: Malformed ICMP packet.");
        Ip::Address::FreeAddr(from);
        return;
    }
 
    control.SendResult(preply, (sizeof(pingerReplyData) - PINGER_PAYLOAD_SZ + preply.psize));
 
    Log(preply.from, icmp->icmp_type, IcmpPacketType(icmp->icmp_type), preply.rtt, preply.hops);
    Ip::Address::FreeAddr(from);
}
 
#endif /* USE_ICMP */