mtrace.c

mtrace源码

	    else
		log(LOG_ERR, 0, "while checking for Solaris bug: Sent %d bytes and got back %d!", IGMP_MINLEN + 8, ip->ip_len);

	    break;
	}
    }
}
#endif

/*
 * Construct an IGMP message in the output packet buffer.  The caller may
 * have already placed data in that buffer, of length 'datalen'.  Then send
 * the message from the interface with IP address 'src' to destination 'dst'.
 */
void
send_igmp(src, dst, type, code, group, datalen)
    u_int32 src, dst;
    int type, code;
    u_int32 group;
    int datalen;
{
    struct sockaddr_in sdst;
    struct ip *ip;
    struct igmp *igmp;
    int setloop = 0;
    static int raset = 0;
    int sendra = 0;
    int sendlen;

    ip                      = (struct ip *)send_buf;
    ip->ip_src.s_addr       = src;
    ip->ip_dst.s_addr       = dst;
    ip->ip_len              = MIN_IP_HEADER_LEN + IGMP_MINLEN + datalen;
    sendlen		    = ip->ip_len;
#ifdef SUNOS5
    ip->ip_len		   += ip_addlen;
#endif
#ifdef RAW_OUTPUT_IS_RAW
    ip->ip_len		    = htons(ip->ip_len);
#endif

    igmp                    = (struct igmp *)(send_buf + MIN_IP_HEADER_LEN);
    igmp->igmp_type         = type;
    igmp->igmp_code         = code;
    igmp->igmp_group.s_addr = group;
    igmp->igmp_cksum        = 0;
    igmp->igmp_cksum        = inet_cksum((u_short *)igmp,
					 IGMP_MINLEN + datalen);

    if (IN_MULTICAST(ntohl(dst))) {
	k_set_if(src);
	setloop = 1;
	k_set_loop(TRUE);
	if (dst != allrtrs_group)
	    sendra = 1;
    }

    if (sendopts && sendra && !raset) {
	setsockopt(igmp_socket, IPPROTO_IP, IP_OPTIONS,
			router_alert, sizeof(router_alert));
	raset = 1;
    } else if (!sendra && raset) {
#ifdef SUNOS5
	/*
	 * SunOS5 < 5.6 cannot properly reset the IP_OPTIONS "socket"
	 * option.  Instead, set up a string of 4 EOL's.
	 */
	setsockopt(igmp_socket, IPPROTO_IP, IP_OPTIONS,
			eol, sizeof(eol));
#else
	setsockopt(igmp_socket, IPPROTO_IP, IP_OPTIONS,
			NULL, 0);
#endif
	raset = 0;
    }

    bzero(&sdst, sizeof(sdst));
    sdst.sin_family = AF_INET;
#if (defined(BSD) && (BSD >= 199103))
    sdst.sin_len = sizeof(sdst);
#endif
    sdst.sin_addr.s_addr = dst;
    if (sendto(igmp_socket, send_buf, sendlen, 0,
			(struct sockaddr *)&sdst, sizeof(sdst)) < 0) {
	    log(LOG_WARNING, errno, "sendto to %s on %s",
		inet_fmt(dst, s1), inet_fmt(src, s2));
    }

    if (setloop)
	    k_set_loop(FALSE);

    log(LOG_DEBUG, 0, "SENT %s from %-15s to %s",
	type == IGMP_MTRACE ? "mtrace request" : "ask_neighbors",
	src == INADDR_ANY ? "INADDR_ANY" : inet_fmt(src, s1),
	inet_fmt(dst, s2));
}

/*
 * inet_cksum extracted from:
 *			P I N G . C
 *
 * Author -
 *	Mike Muuss
 *	U. S. Army Ballistic Research Laboratory
 *	December, 1983
 * Modified at Uc Berkeley
 *
 * (ping.c) Status -
 *	Public Domain.  Distribution Unlimited.
 *
 *			I N _ C K S U M
 *
 * Checksum routine for Internet Protocol family headers (C Version)
 *
 */
int
inet_cksum(addr, len)
	u_short *addr;
	u_int len;
{
	register int nleft = (int)len;
	register u_short *w = addr;
	u_short answer = 0;
	register int sum = 0;

	/*
	 *  Our algorithm is simple, using a 32 bit accumulator (sum),
	 *  we add sequential 16 bit words to it, and at the end, fold
	 *  back all the carry bits from the top 16 bits into the lower
	 *  16 bits.
	 */
	while (nleft > 1)  {
		sum += *w++;
		nleft -= 2;
	}

	/* mop up an odd byte, if necessary */
	if (nleft == 1) {
		*(u_char *) (&answer) = *(u_char *)w ;
		sum += answer;
	}

	/*
	 * add back carry outs from top 16 bits to low 16 bits
	 */
	sum = (sum >> 16) + (sum & 0xffff);	/* add hi 16 to low 16 */
	sum += (sum >> 16);			/* add carry */
	answer = ~sum;				/* truncate to 16 bits */
	return (answer);
}

void
k_set_rcvbuf(bufsize)
    int bufsize;
{
    if (setsockopt(igmp_socket, SOL_SOCKET, SO_RCVBUF,
		   (char *)&bufsize, sizeof(bufsize)) < 0)
	log(LOG_ERR, errno, "setsockopt SO_RCVBUF %u", bufsize);
}


void
k_hdr_include(bool)
    int bool;
{
#ifdef IP_HDRINCL
    if (setsockopt(igmp_socket, IPPROTO_IP, IP_HDRINCL,
		   (char *)&bool, sizeof(bool)) < 0)
	log(LOG_ERR, errno, "setsockopt IP_HDRINCL %u", bool);
#endif
}

void
k_set_ttl(t)
    int t;
{
    u_char ttl;

    ttl = t;
    if (setsockopt(igmp_socket, IPPROTO_IP, IP_MULTICAST_TTL,
		   (char *)&ttl, sizeof(ttl)) < 0)
	log(LOG_ERR, errno, "setsockopt IP_MULTICAST_TTL %u", ttl);
}


void
k_set_loop(l)
    int l;
{
    u_char loop;

    loop = l;
    if (setsockopt(igmp_socket, IPPROTO_IP, IP_MULTICAST_LOOP,
		   (char *)&loop, sizeof(loop)) < 0)
	log(LOG_ERR, errno, "setsockopt IP_MULTICAST_LOOP %u", loop);
}

void
k_set_if(ifa)
    u_int32 ifa;
{
    struct in_addr adr;

    adr.s_addr = ifa;
    if (setsockopt(igmp_socket, IPPROTO_IP, IP_MULTICAST_IF,
		   (char *)&adr, sizeof(adr)) < 0)
	log(LOG_ERR, errno, "setsockopt IP_MULTICAST_IF %s",
	    		    inet_fmt(ifa, s1));
}

void
k_join(grp, ifa)
    u_int32 grp;
    u_int32 ifa;
{
    struct ip_mreq mreq;

    mreq.imr_multiaddr.s_addr = grp;
    mreq.imr_interface.s_addr = ifa;

    if (setsockopt(igmp_socket, IPPROTO_IP, IP_ADD_MEMBERSHIP,
		   (char *)&mreq, sizeof(mreq)) < 0)
	log(LOG_WARNING, errno, "can't join group %s on interface %s",
				inet_fmt(grp, s1), inet_fmt(ifa, s2));
}


void
k_leave(grp, ifa)
    u_int32 grp;
    u_int32 ifa;
{
    struct ip_mreq mreq;

    mreq.imr_multiaddr.s_addr = grp;
    mreq.imr_interface.s_addr = ifa;

    if (setsockopt(igmp_socket, IPPROTO_IP, IP_DROP_MEMBERSHIP,
		   (char *)&mreq, sizeof(mreq)) < 0)
	log(LOG_WARNING, errno, "can't leave group %s on interface %s",
				inet_fmt(grp, s1), inet_fmt(ifa, s2));
}

/*
 * Convert an IP address in u_long (network) format into a printable string.
 */
char *
inet_fmt(addr, s)
    u_int32 addr;
    char *s;
{
    register u_char *a;

    a = (u_char *)&addr;
    sprintf(s, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]);
    return (s);
}


/*
 * Convert an IP subnet number in u_long (network) format into a printable
 * string including the netmask as a number of bits.
 */
char *
inet_fmts(addr, mask, s)
    u_int32 addr, mask;
    char *s;
{
    register u_char *a, *m;
    int bits;

    if ((addr == 0) && (mask == 0)) {
	sprintf(s, "default");
	return (s);
    }
    a = (u_char *)&addr;
    m = (u_char *)&mask;
    bits = 33 - ffs(ntohl(mask));

    if      (m[3] != 0) sprintf(s, "%u.%u.%u.%u/%d", a[0], a[1], a[2], a[3],
						bits);
    else if (m[2] != 0) sprintf(s, "%u.%u.%u/%d",    a[0], a[1], a[2], bits);
    else if (m[1] != 0) sprintf(s, "%u.%u/%d",       a[0], a[1], bits);
    else                sprintf(s, "%u/%d",          a[0], bits);

    return (s);
}

char   *
inet_name(addr)
    u_int32  addr;
{
    struct hostent *e;

    e = gethostbyaddr((char *)&addr, sizeof(addr), AF_INET);

    return e ? e->h_name : "?";
}


u_int32 
host_addr(name)
    char   *name;
{
    struct hostent *e = (struct hostent *)0;
    u_int32  addr;
    int	i, dots = 3;
    char	buf[40];
    char	*ip = name;
    char	*op = buf;

    /*
     * Undo BSD's favor -- take fewer than 4 octets as net/subnet address
     * if the name is all numeric.
     */
    for (i = sizeof(buf) - 7; i > 0; --i) {
	if (*ip == '.') --dots;
	else if (*ip == '\0') break;
	else if (!isdigit(*ip)) dots = 0;  /* Not numeric, don't add zeroes */
	*op++ = *ip++;
    }
    for (i = 0; i < dots; ++i) {
	*op++ = '.';
	*op++ = '0';
    }
    *op = '\0';

    if (dots <= 0)
	e = gethostbyname(name);
    if (e && (e->h_length == sizeof(addr))) {
	memcpy((char *)&addr, e->h_addr_list[0], e->h_length);
	if (e->h_addr_list[1])
	    fprintf(stderr, "Warning: %s has multiple addresses, using %s\n",
			name, inet_fmt(addr, s1));
    } else {
	addr = inet_addr(buf);
	if (addr == -1 || (IN_MULTICAST(addr) && dots)) {
	    addr = 0;
	    printf("Could not parse %s as host name or address\n", name);
	}
    }
    return addr;
}


char *
proto_type(type)
    u_int type;
{
    static char buf[80];

    switch (type) {
      case PROTO_DVMRP:
	return ("DVMRP");
      case PROTO_MOSPF:
	return ("MOSPF");
      case PROTO_PIM:
	return ("PIM");
      case PROTO_CBT:
	return ("CBT");
      case PROTO_PIM_SPECIAL:
	return ("PIM/Special");
      case PROTO_PIM_STATIC:
	return ("PIM/Static");
      case PROTO_DVMRP_STATIC:
	return ("DVMRP/Static");
      case PROTO_PIM_BGP4PLUS:
	return ("PIM/BGP4+");
      case PROTO_CBT_SPECIAL:
	return ("CBT/Special");
      case PROTO_CBT_STATIC:
	return ("CBT/Static");
      case PROTO_PIM_ASSERT:
	return ("PIM/Assert");
      case 0:
	return ("None");
      default:
	(void) sprintf(buf, "Unknown protocol code %d", type);
	return (buf);
    }
}


char *
flag_type(type)
    u_int type;
{
    static char buf[80];

    switch (type) {
      case TR_NO_ERR:
	return ("");
      case TR_WRONG_IF:
	return ("Wrong interface");
      case TR_PRUNED:
	return ("Prune sent upstream");
      case TR_OPRUNED:
	return ("Output pruned");
      case TR_SCOPED:
	return ("Hit scope boundary");
      case TR_NO_RTE:
	return ("No route");
      case TR_NO_FWD:
	return ("Not forwarding");
      case TR_HIT_RP:
	return ("Reached RP/Core");
      case TR_RPF_IF:
	return ("RPF Interface");
      case TR_NO_MULTI:
	return ("Multicast disabled");
      case TR_OLD_ROUTER:
	return ("Next router no mtrace");
      case TR_NO_SPACE:
	return ("No space in packet");
      case TR_ADMIN_PROHIB:
	return ("Admin. Prohibited");
      default:
	(void) sprintf(buf, "Unknown error code %d", type);
	return (buf);
    }
}    

/*
 * If destination is on a local net, get the netmask, else set the
 * netmask to all ones.  There are two side effects: if the local
 * address was not explicitly set, and if the destination is on a
 * local net, use that one; in either case, verify that the local
 * address is valid.
 */
u_int32
get_netmask(s, dst)
    int s;
    u_int32 *dst;
{
    unsigned int n;
    struct ifconf ifc;
    struct ifreq *ifrp, *ifend;
    u_int32 if_addr, if_mask;
    u_int32 retval = 0xFFFFFFFF;
    int found = FALSE;
    int num_ifreq = 32;

    ifc.ifc_len = num_ifreq * sizeof(struct ifreq);
    ifc.ifc_buf = malloc(ifc.ifc_len);
    while (ifc.ifc_buf) {
	if (ioctl(s, SIOCGIFCONF, (char *)&ifc) < 0) {
	    perror("ioctl SIOCGIFCONF");
	    return retval;
	}

	/*
	 * If the buffer was large enough to hold all the addresses
	 * then break out, otherwise increase the buffer size and
	 * try again.
	 *
	 * The only way to know that we definitely had enough space
	 * is to know that there was enough space for at least one
	 * more struct ifreq. ???
	 */
	if ((num_ifreq * sizeof(struct ifreq)) >=
	     ifc.ifc_len + sizeof(struct ifreq))
	     break;

	num_ifreq *= 2;
	ifc.ifc_len = num_ifreq * sizeof(struct ifreq);
	ifc.ifc_buf = realloc(ifc.ifc_buf, ifc.ifc_len);
    }
    if (ifc.ifc_buf == NULL) {
	fprintf(stderr, "getting interface list: ran out of memory");
	exit(1);
    }