usr.sbin/traceroute/traceroute_aux.c

	traceroute_aux.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 1988, 1989, 1991, 1994, 1995, 1996, 1997
 *  The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE 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.
 *
 *
 * @(#)$Header: traceroute.c,v 1.49 97/06/13 02:30:23 leres Exp $ (LBL)
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/socket.h>

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <strings.h>
#include <libintl.h>
#include <errno.h>

#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>

#include <arpa/inet.h>
#include <netdb.h>

#include <ifaddrlist.h>
#include "traceroute.h"

/*
 * IPv4 source routing option.
 * In order to avoid padding for the alignment of IPv4 addresses, ipsr_addrs
 * is defined as a 2-D array of uint8_t, instead of 1-D array of struct in_addr.
 */
struct ip_sourceroute {
    uint8_t ipsr_code;
    uint8_t ipsr_len;
    uint8_t ipsr_ptr;
    /* up to 9 IPv4 addresses */
    uint8_t ipsr_addrs[1][sizeof (struct in_addr)];
};

int check_reply(struct msghdr *, int, int, uchar_t *, uchar_t *);
extern ushort_t in_cksum(ushort_t *, int);
extern char *inet_name(union any_in_addr *, int);
static char *pr_type(uchar_t);
void print_addr(uchar_t *, int, struct sockaddr *);
boolean_t print_icmp_other(uchar_t, uchar_t);
void send_probe(int, struct sockaddr *, struct ip *, int, int,
    struct timeval *, int);
struct ip *set_buffers(int);
void set_IPv4opt_sourcerouting(int, union any_in_addr *, union any_in_addr *);

/*
 * prepares the buffer to be sent as an IP datagram
 */
struct ip *
set_buffers(int plen)
{
    struct ip *outip;
    uchar_t *outp;      /* packet following the IP header (UDP/ICMP) */
    struct udphdr *outudp;
    struct icmp *outicmp;
    int optlen = 0;

    outip = (struct ip *)malloc((size_t)plen);
    if (outip == NULL) {
        Fprintf(stderr, "%s: malloc: %s\n", prog, strerror(errno));
        exit(EXIT_FAILURE);
    }

    if (gw_count > 0) {
        /* 8 = 5 (NO OPs) + 3 (code, len, ptr) */
        optlen = 8 + gw_count * sizeof (struct in_addr);
    }

    (void) memset((char *)outip, 0, (size_t)plen);
    outp = (uchar_t *)(outip + 1);

    outip->ip_v = IPVERSION;
    if (settos)
        outip->ip_tos = tos;

    /*
     * LBNL bug fixed: missing '- optlen' before, causing optlen
     * added twice
     *
     * BSD bug: BSD touches the header fields 'len' and 'ip_off'
     * even when HDRINCL is set. It applies htons() on these
     * fields. It should send the header untouched when HDRINCL
     * is set.
     */
    outip->ip_len = htons(plen - optlen);
    outip->ip_off = htons(off);
    outip->ip_hl = (outp - (uchar_t *)outip) >> 2;

    /* setup ICMP or UDP */
    if (useicmp) {
        outip->ip_p = IPPROTO_ICMP;

        /* LINTED E_BAD_PTR_CAST_ALIGN */
        outicmp = (struct icmp *)outp;
        outicmp->icmp_type = ICMP_ECHO;
        outicmp->icmp_id = htons(ident);
    } else {
        outip->ip_p = IPPROTO_UDP;

        /* LINTED E_BAD_PTR_CAST_ALIGN */
        outudp = (struct udphdr *)outp;
        outudp->uh_sport = htons(ident);
        outudp->uh_ulen =
            htons((ushort_t)(plen - (sizeof (struct ip) + optlen)));
    }

    return (outip);
}

/*
 * Setup the source routing for IPv4.
 */
void
set_IPv4opt_sourcerouting(int sndsock, union any_in_addr *ip_addr,
    union any_in_addr *gwIPlist)
{
    struct protoent *pe;
    struct ip_sourceroute *srp;
    uchar_t optlist[MAX_IPOPTLEN];
    int i;

    if ((pe = getprotobyname("ip")) == NULL) {
        Fprintf(stderr, "%s: unknown protocol ip\n", prog);
        exit(EXIT_FAILURE);
    }

    /* final hop */
    gwIPlist[gw_count].addr = ip_addr->addr;

    /*
     * the option length passed to setsockopt() needs to be a multiple of
     * 32 bits. Therefore we need to use a 1-byte padding (source routing
     * information takes 4x+3 bytes).
     */
    optlist[0] = IPOPT_NOP;

    srp = (struct ip_sourceroute *)&optlist[1];
    srp->ipsr_code = IPOPT_LSRR;
    /* 3 = 1 (code) + 1 (len) + 1 (ptr) */
    srp->ipsr_len = 3 + (gw_count + 1) * sizeof (gwIPlist[0].addr);
    srp->ipsr_ptr = IPOPT_MINOFF;

    for (i = 0; i <= gw_count; i++) {
        (void) bcopy((char *)&gwIPlist[i].addr, &srp->ipsr_addrs[i],
            sizeof (struct in_addr));
    }

    if (setsockopt(sndsock, pe->p_proto, IP_OPTIONS, (const char *)optlist,
        srp->ipsr_len + 1) < 0) {
        Fprintf(stderr, "%s: IP_OPTIONS: %s\n", prog, strerror(errno));
        exit(EXIT_FAILURE);
    }
}

/*
 * send a probe packet to the destination
 */
void
send_probe(int sndsock, struct sockaddr *to, struct ip *outip,
    int seq, int ttl, struct timeval *tp, int packlen)
{
    int cc;
    struct udpiphdr *ui;
    uchar_t *outp;      /* packet following the IP header (UDP/ICMP) */
    struct udphdr *outudp;
    struct icmp *outicmp;
    struct outdata *outdata;
    struct ip tip;
    int optlen = 0;
    int send_size;

    /* initialize buffer pointers */
    outp = (uchar_t *)(outip + 1);
    /* LINTED E_BAD_PTR_CAST_ALIGN */
    outudp =  (struct udphdr *)outp;
    /* LINTED E_BAD_PTR_CAST_ALIGN */
    outicmp = (struct icmp *)outp;
    /* LINTED E_BAD_PTR_CAST_ALIGN */
    outdata = (struct outdata *)(outp + ICMP_MINLEN);

    if (gw_count > 0) {
        /* 8 = 5 (NO OPs) + 3 (code, len, ptr) */
        optlen = 8 + gw_count * sizeof (struct in_addr);
    }

    if (raw_req) {
        send_size = packlen - optlen;
    } else if (useicmp) {
        send_size = packlen - optlen - sizeof (struct ip);
    } else {
        send_size = packlen - optlen - sizeof (struct ip) -
            sizeof (struct udphdr);
    }

    outip->ip_ttl = ttl;
    outip->ip_id = htons(ident + seq);

    /*
     * If a raw IPv4 packet is going to be sent, the Time to Live
     * field in the packet was initialized above.  Otherwise, it is
     * initialized here using the IPPROTO_IP level socket option.
     */
    if (!raw_req) {
        if (setsockopt(sndsock, IPPROTO_IP, IP_TTL, (char *)&ttl,
            sizeof (ttl)) < 0) {
            Fprintf(stderr, "%s: IP_TTL: %s\n", prog,
                strerror(errno));
            exit(EXIT_FAILURE);
        }
    }

    /*
     * In most cases, the kernel will recalculate the ip checksum.
     * But we must do it anyway so that the udp checksum comes out
     * right.
     */
    if (docksum) {
        outip->ip_sum =
            in_cksum((ushort_t *)outip, sizeof (*outip) + optlen);
        if (outip->ip_sum == 0)
            outip->ip_sum = 0xffff;
    }

    /* Payload */
    outdata->seq = seq;
    outdata->ttl = ttl;
    outdata->tv = *tp;

    if (useicmp) {
        outicmp->icmp_seq = htons(seq);
    } else {
        outudp->uh_dport  = htons((port + seq) % (MAX_PORT + 1));
    }

    if (!raw_req)
        /* LINTED E_BAD_PTR_CAST_ALIGN */
        ((struct sockaddr_in *)to)->sin_port = outudp->uh_dport;

    /* (We can only do the checksum if we know our ip address) */
    if (docksum) {
        if (useicmp) {
            outicmp->icmp_cksum = 0;
            outicmp->icmp_cksum = in_cksum((ushort_t *)outicmp,
                packlen - (sizeof (struct ip) + optlen));
            if (outicmp->icmp_cksum == 0)
                outicmp->icmp_cksum = 0xffff;
        } else {
            /* Checksum (must save and restore ip header) */
            tip = *outip;
            ui = (struct udpiphdr *)outip;
            ui->ui_next = 0;
            ui->ui_prev = 0;
            ui->ui_x1 = 0;
            ui->ui_len = outudp->uh_ulen;
            outudp->uh_sum = 0;
            outudp->uh_sum = in_cksum((ushort_t *)ui, packlen);
            if (outudp->uh_sum == 0)
                outudp->uh_sum = 0xffff;
            *outip = tip;
        }
    }

    if (raw_req) {
        cc = sendto(sndsock, (char *)outip, send_size, 0, to,
            sizeof (struct sockaddr_in));
    } else if (useicmp) {
        cc = sendto(sndsock, (char *)outicmp, send_size, 0, to,
            sizeof (struct sockaddr_in));
    } else {
        cc = sendto(sndsock, (char *)outp, send_size, 0, to,
            sizeof (struct sockaddr_in));
    }

    if (cc < 0 || cc != send_size)  {
        if (cc < 0) {
            Fprintf(stderr, "%s: sendto: %s\n", prog,
                strerror(errno));
        }
        Printf("%s: wrote %s %d chars, ret=%d\n",
            prog, hostname, send_size, cc);
        (void) fflush(stdout);
    }
}

/*
 * Check out the reply packet to see if it's what we were expecting.
 * Returns REPLY_GOT_TARGET if the reply comes from the target
 *         REPLY_GOT_GATEWAY if an intermediate gateway sends TIME_EXCEEDED
 *         REPLY_GOT_OTHER for other kinds of unreachables indicating none of
 *     the above two cases
 *
 * It also sets the icmp type and icmp code values
 */
int
check_reply(struct msghdr *msg, int cc, int seq, uchar_t *type, uchar_t *code)
{
    uchar_t *buf = msg->msg_iov->iov_base;
    struct sockaddr_in *from_in = (struct sockaddr_in *)msg->msg_name;
    struct icmp *icp;
    int hlen;
    int save_cc = cc;
    struct ip *ip;

    /* LINTED E_BAD_PTR_CAST_ALIGN */
    ip = (struct ip *)buf;
    hlen = ip->ip_hl << 2;
    if (cc < hlen + ICMP_MINLEN) {
        if (verbose) {
            Printf("packet too short (%d bytes) from %s\n",
                cc, inet_ntoa(from_in->sin_addr));
        }
        return (REPLY_SHORT_PKT);
    }
    cc -= hlen;
    /* LINTED E_BAD_PTR_CAST_ALIGN */
    icp = (struct icmp *)(buf + hlen);

    *type = icp->icmp_type;
    *code = icp->icmp_code;

    /*
     * traceroute interpretes only ICMP_TIMXCEED_INTRANS, ICMP_UNREACH and
     * ICMP_ECHOREPLY, ignores others
     */
    if ((*type == ICMP_TIMXCEED && *code == ICMP_TIMXCEED_INTRANS) ||
        *type == ICMP_UNREACH || *type == ICMP_ECHOREPLY) {
        struct ip *hip;
        struct udphdr *up;
        struct icmp *hicmp;

        cc -= ICMP_MINLEN;
        hip = &icp->icmp_ip;
        hlen = hip->ip_hl << 2;
        cc -= hlen;
        if (useicmp) {
            if (*type == ICMP_ECHOREPLY &&
                icp->icmp_id == htons(ident) &&
                icp->icmp_seq == htons(seq))
                return (REPLY_GOT_TARGET);

            /* LINTED E_BAD_PTR_CAST_ALIGN */
            hicmp = (struct icmp *)((uchar_t *)hip + hlen);

            if (ICMP_MINLEN <= cc &&
                hip->ip_p == IPPROTO_ICMP &&
                hicmp->icmp_id == htons(ident) &&
                hicmp->icmp_seq == htons(seq)) {
                return ((*type == ICMP_TIMXCEED) ?
                    REPLY_GOT_GATEWAY : REPLY_GOT_OTHER);
            }
        } else {
            /* LINTED E_BAD_PTR_CAST_ALIGN */
            up = (struct udphdr *)((uchar_t *)hip + hlen);
            /*
             * at least 4 bytes of UDP header is required for this
             * check
             */
            if (4 <= cc &&
                hip->ip_p == IPPROTO_UDP &&
                up->uh_sport == htons(ident) &&
                up->uh_dport == htons((port + seq) %
                (MAX_PORT + 1))) {
                if (*type == ICMP_UNREACH &&
                    *code == ICMP_UNREACH_PORT) {
                    return (REPLY_GOT_TARGET);
                } else if (*type == ICMP_TIMXCEED) {
                    return (REPLY_GOT_GATEWAY);
                } else {
                    return (REPLY_GOT_OTHER);
                }
            }
        }
    }

    if (verbose) {
        int i, j;
        uchar_t *lp = (uchar_t *)ip;

        cc = save_cc;
        Printf("\n%d bytes from %s to ", cc,
            inet_ntoa(from_in->sin_addr));
        Printf("%s: icmp type %d (%s) code %d\n",
            inet_ntoa(ip->ip_dst), *type, pr_type(*type), *code);
        for (i = 0; i < cc; i += 4) {
            Printf("%2d: x", i);
            for (j = 0; ((j < 4) && ((i + j) < cc)); j++)
                Printf("%2.2x", *lp++);
            (void) putchar('\n');
        }
    }

    return (REPLY_SHORT_PKT);
}

/*
 * convert an ICMP "type" field to a printable string.
 */
static char *
pr_type(uchar_t type)
{
    static struct icmptype_table ttab[] = {
        {ICMP_ECHOREPLY,    "Echo Reply"},
        {1,         "ICMP 1"},
        {2,         "ICMP 2"},
        {ICMP_UNREACH,      "Dest Unreachable"},
        {ICMP_SOURCEQUENCH, "Source Quench"},
        {ICMP_REDIRECT,     "Redirect"},
        {6,         "ICMP 6"},
        {7,         "ICMP 7"},
        {ICMP_ECHO,     "Echo"},
        {ICMP_ROUTERADVERT, "Router Advertisement"},
        {ICMP_ROUTERSOLICIT,    "Router Solicitation"},
        {ICMP_TIMXCEED,     "Time Exceeded"},
        {ICMP_PARAMPROB,    "Param Problem"},
        {ICMP_TSTAMP,       "Timestamp"},
        {ICMP_TSTAMPREPLY,  "Timestamp Reply"},
        {ICMP_IREQ,     "Info Request"},
        {ICMP_IREQREPLY,    "Info Reply"},
        {ICMP_MASKREQ,      "Netmask Request"},
        {ICMP_MASKREPLY,    "Netmask Reply"}
    };
    int i = 0;

    for (i = 0; i < A_CNT(ttab); i++) {
        if (ttab[i].type == type)
            return (ttab[i].message);
    }

    return ("OUT-OF-RANGE");
}

/*
 * print the IPv4 src address of the reply packet
 */
void
print_addr(uchar_t *buf, int cc, struct sockaddr *from)
{
    /* LINTED E_BAD_PTR_CAST_ALIGN */
    struct sockaddr_in *from_in = (struct sockaddr_in *)from;
    struct ip *ip;
    union any_in_addr ip_addr;

    ip_addr.addr = from_in->sin_addr;

    /* LINTED E_BAD_PTR_CAST_ALIGN */
    ip = (struct ip *)buf;

    if (nflag) {
        Printf(" %s", inet_ntoa(from_in->sin_addr));
    } else {
        Printf(" %s (%s)", inet_name(&ip_addr, AF_INET),
            inet_ntoa(from_in->sin_addr));
    }

    if (verbose)
        Printf(" %d bytes to %s", cc, inet_ntoa(ip->ip_dst));
}

/*
 * ICMP messages which doesn't mean we got the target, or we got a gateway, are
 * processed here. It returns _B_TRUE if it's some sort of 'unreachable'.
 */
boolean_t
print_icmp_other(uchar_t type, uchar_t code)
{
    boolean_t unreach = _B_FALSE;

    /*
     * this function only prints '!*' for ICMP unreachable messages,
     * ignores others.
     */
    if (type != ICMP_UNREACH) {
        return (_B_FALSE);
    }

    switch (code) {
    case ICMP_UNREACH_PORT:
        break;

    case ICMP_UNREACH_NET_UNKNOWN:
    case ICMP_UNREACH_NET:
        unreach = _B_TRUE;
        Printf(" !N");
        break;

    case ICMP_UNREACH_HOST_UNKNOWN:
    case ICMP_UNREACH_HOST:
        unreach = _B_TRUE;
        Printf(" !H");
        break;

    case ICMP_UNREACH_PROTOCOL:
        Printf(" !P");
        break;

    case ICMP_UNREACH_NEEDFRAG:
        unreach = _B_TRUE;
        Printf(" !F");
        break;

    case ICMP_UNREACH_SRCFAIL:
        unreach = _B_TRUE;
        Printf(" !S");
        break;

    case ICMP_UNREACH_FILTER_PROHIB:
    case ICMP_UNREACH_NET_PROHIB:
    case ICMP_UNREACH_HOST_PROHIB:
        unreach = _B_TRUE;
        Printf(" !X");
        break;

    case ICMP_UNREACH_TOSNET:
    case ICMP_UNREACH_TOSHOST:
        unreach = _B_TRUE;
        Printf(" !T");
        break;

    case ICMP_UNREACH_ISOLATED:
    case ICMP_UNREACH_HOST_PRECEDENCE:
    case ICMP_UNREACH_PRECEDENCE_CUTOFF:
        unreach = _B_TRUE;
        Printf(" !U");
        break;

    default:
        unreach = _B_TRUE;
        Printf(" !<%d>", code);
        break;
    }

    return (unreach);
}