3 * Report MTU on path to specified host
5 * (c) 2008 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Trivial IP Encryption (TrIPE).
12 * TrIPE is free software: you can redistribute it and/or modify it under
13 * the terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 3 of the License, or (at your
15 * option) any later version.
17 * TrIPE is distributed in the hope that it will be useful, but WITHOUT
18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
22 * You should have received a copy of the GNU General Public License
23 * along with TrIPE. If not, see <https://www.gnu.org/licenses/>.
26 /*----- Header files ------------------------------------------------------*/
38 #include <sys/types.h>
42 #include <sys/socket.h>
43 #include <netinet/in.h>
44 #include <arpa/inet.h>
47 #include <netinet/in_systm.h>
48 #include <netinet/ip.h>
49 #include <netinet/ip_icmp.h>
50 #include <netinet/ip6.h>
51 #include <netinet/icmp6.h>
52 #include <netinet/udp.h>
54 #ifdef HAVE_GETIFADDRS
57 # include <sys/ioctl.h>
60 #include <mLib/alloc.h>
61 #include <mLib/bits.h>
62 #include <mLib/dstr.h>
64 #include <mLib/mdwopt.h>
65 #include <mLib/quis.h>
66 #include <mLib/report.h>
69 /*----- Static variables --------------------------------------------------*/
71 static unsigned char buf[65536];
75 /*----- Utility functions -------------------------------------------------*/
77 /* Step a value according to a simple LFSR. */
79 do (q) = ((q) & 0x8000) ? ((q) << 1) ^ POLY : ((q) << 1); while (0)
81 /* Fill buffer with a constant but pseudorandom string. Uses a simple
84 static void fillbuffer(unsigned char *p, size_t sz)
86 unsigned int y = 0xbc20;
87 const unsigned char *l = p + sz;
92 for (i = 0; i < 8; i++) STEP(y);
96 /* Convert a string to floating point. */
97 static double s2f(const char *s, const char *what)
104 if (errno || *q) die(EXIT_FAILURE, "bad %s", what);
108 /* Convert a floating-point value into a struct timeval. */
109 static void f2tv(struct timeval *tv, double t)
110 { tv->tv_sec = t; tv->tv_usec = (t - tv->tv_sec)*MILLION; }
114 struct sockaddr_in sin;
115 struct sockaddr_in6 sin6;
118 /* Check whether an address family is even slightly supported. */
119 static int addrfamok(int af)
122 case AF_INET: case AF_INET6: return (1);
127 /* Return the size of a socket address. */
128 static size_t addrsz(const union addr *a)
130 switch (a->sa.sa_family) {
131 case AF_INET: return (sizeof(a->sin));
132 case AF_INET6: return (sizeof(a->sin6));
137 /*----- Main algorithm skeleton -------------------------------------------*/
140 unsigned f; /* Various flags */
141 #define F_VERBOSE 1u /* Give a running commentary */
142 double retx; /* Initial retransmit interval */
143 double regr; /* Retransmit growth factor */
144 double timeout; /* Retransmission timeout */
145 int seqoff; /* Offset to write sequence number */
146 const struct probe_ops *pops; /* Probe algorithm description */
147 union addr a; /* Destination address */
151 const struct param *pp;
157 const struct probe_ops *next;
159 int (*setup)(void *, int, const struct param *);
160 void (*finish)(void *);
161 void (*selprep)(void *, int *, fd_set *);
162 int (*xmit)(void *, int);
163 int (*selproc)(void *, fd_set *, struct probestate *);
174 /* or a positive MTU upper-bound */
177 /* Add a file descriptor FD to the set `fd_in', updating `*maxfd'. */
179 do { FD_SET(fd, fd_in); if (*maxfd < fd) *maxfd = fd; } while (0)
181 /* Check whether a buffer contains a packet from our current probe. */
182 static int mypacketp(struct probestate *ps,
183 const unsigned char *p, size_t sz)
185 const struct param *pp = ps->pp;
187 return (sz >= pp->seqoff + 2 && LOAD16(p + pp->seqoff) == ps->q);
190 /* See whether MTU is an acceptable MTU value. Return an appropriate
191 * RC_... code or a new suggested MTU.
193 static int probe(struct probestate *ps, void *st, int mtu)
195 const struct param *pp = ps->pp;
197 struct timeval tv, now, when, done;
198 double timer = pp->retx;
201 /* Set up the first retransmit and give-up timers. */
202 gettimeofday(&now, 0);
203 f2tv(&tv, pp->timeout); TV_ADD(&done, &now, &tv);
204 f2tv(&tv, timer); TV_ADD(&when, &now, &tv);
205 if (TV_CMP(&when, >, &done)) when = done;
207 /* Send the initial probe. */
208 if (pp->f & F_VERBOSE)
209 moan("sending probe of size %d (seq = %04x)", mtu, ps->q);
211 STORE16(buf + pp->seqoff, ps->q);
212 if ((rc = pp->pops->xmit(st, mtu)) != RC_OK) return (rc);
216 /* Wait for something interesting to happen. */
217 maxfd = 0; FD_ZERO(&fd_in);
218 pp->pops->selprep(st, &maxfd, &fd_in);
219 TV_SUB(&tv, &when, &now);
220 if (select(maxfd + 1, &fd_in, 0, 0, &tv) < 0) return (RC_FAIL);
221 gettimeofday(&now, 0);
223 /* See whether the probe method has any answers for us. */
224 if ((rc = pp->pops->selproc(st, &fd_in, ps)) != RC_OK) return (rc);
226 /* If we've waited too long, give up. If we should retransmit, do
229 if (TV_CMP(&now, >, &done))
231 else if (TV_CMP(&now, >, &when)) {
232 if (pp->f & F_VERBOSE) moan("re-sending probe of size %d", mtu);
233 if ((rc = pp->pops->xmit(st, mtu)) != RC_OK) return (rc);
235 timer *= pp->regr; f2tv(&tv, timer); TV_ADD(&when, &when, &tv);
236 } while (TV_CMP(&when, <, &now));
237 if (TV_CMP(&when, >, &done)) when = done;
242 /* Discover the path MTU to the destination address. */
243 static int pathmtu(const struct param *pp)
249 struct probestate ps;
251 /* Build and connect a UDP socket. We'll need this to know the local port
252 * number to use if nothing else. Set other stuff up.
254 if ((sk = socket(pp->a.sa.sa_family, SOCK_DGRAM, IPPROTO_UDP)) < 0)
256 if (connect(sk, &pp->a.sa, addrsz(&pp->a))) goto fail_1;
257 st = xmalloc(pp->pops->statesz);
258 if ((mtu = pp->pops->setup(st, sk, pp)) < 0) goto fail_2;
259 ps.pp = pp; ps.q = rand() & 0xffff;
260 switch (pp->a.sa.sa_family) {
261 case AF_INET: lo = 576; break;
262 case AF_INET6: lo = 1280; break;
266 if (hi < lo) { errno = EMSGSIZE; return (-1); }
268 /* And now we do a thing which is sort of like a binary search, except that
269 * we also take explicit clues as establishing a new upper bound, and we
270 * try to hug that initially.
273 assert(lo <= mtu && mtu <= hi);
274 if (pp->f & F_VERBOSE) moan("probe: %d <= %d <= %d", lo, mtu, hi);
275 rc = probe(&ps, st, mtu);
279 if (pp->f & F_VERBOSE) moan("probe failed");
283 /* If we've not seen a dropped packet before then we don't know what
284 * this means yet -- in particular, we don't know which bit of the
285 * network is swallowing packets. Send a minimum-size probe. If
286 * that doesn't come back then assume that the remote host is
287 * swallowing our packets. If it does, then we assume that dropped
288 * packets are a result of ICMP fragmentation-needed reports being
289 * lost or suppressed.
291 if (pp->f & F_VERBOSE) moan("gave up: black hole detected");
293 if (pp->f & F_VERBOSE) moan("sending minimum-size probe");
294 switch (probe(&ps, st, lo)) {
298 if (pp->f & F_VERBOSE) {
299 moan("no reply from min-size probe: "
300 "assume black hole at target");
305 if (pp->f & F_VERBOSE) {
306 moan("reply from min-size probe OK: "
307 "assume black hole in network");
312 if (pp->f & F_VERBOSE)
313 moan("unexpected return code from probe");
319 if (droppy) goto higher; else goto lower;
324 if (pp->f & F_VERBOSE)
325 moan("probe returned: remote host is not a black hole");
329 if (pp->f & F_VERBOSE) moan("probe returned: found correct MTU");
334 /* Now we must make a new guess, between lo and hi. We know that lo
335 * is good; but we're not so sure about hi here. We know that hi >
336 * lo, so this will find an approximate midpoint, greater than lo and
339 if (pp->f & F_VERBOSE) moan("probe returned: guessing higher");
340 mtu += (hi - lo + 1)/2;
345 /* If this didn't work, and we're already at the bottom of our
346 * possible range, then something has gone horribly wrong.
351 if (pp->f & F_VERBOSE) moan("error returned: found correct MTU");
356 /* We must make a new guess, between lo and hi. We're probably
357 * fairly sure that lo will succeed, since either it's the minimum
358 * MTU or we've tested it already; but we're not quite sure about hi,
359 * so we want to aim high.
361 if (pp->f & F_VERBOSE) moan("error returned: guessing lower");
362 mtu -= (hi - lo + 1)/2;
366 if (pp->f & F_VERBOSE) moan("error returned with new MTU estimate");
373 /* Clean up and return our result. */
374 pp->pops->finish(st);
380 pp->pops->finish(st);
389 /*----- Doing it the hard way ---------------------------------------------*/
391 #ifdef HAVE_GETIFADDRS
393 #if defined(linux) || defined(__OpenBSD__)
398 # define sane_htons htons
399 # define sane_htonl htonl
405 static int rawicmp = -1, rawudp = -1, rawerr = 0;
406 static int rawicmp6 = -1, rawudp6 = -1, rawerr6 = 0;
408 #define IPCK_INIT 0xffff
410 /* Compare two addresses. Maybe compare the port numbers too. */
412 static int addreq(const union addr *a, const union addr *b, unsigned f)
414 switch (a->sa.sa_family) {
416 return (a->sin.sin_addr.s_addr == b->sin.sin_addr.s_addr &&
417 (!(f&AEF_PORT) || a->sin.sin_port == b->sin.sin_port));
419 return (!memcmp(a->sin6.sin6_addr.s6_addr,
420 b->sin6.sin6_addr.s6_addr, 16) &&
421 (!(f&AEF_PORT) || a->sin6.sin6_port == b->sin6.sin6_port));
427 /* Compute an IP checksum over some data. This is a restartable interface:
428 * initialize A to `IPCK_INIT' for the first call.
430 static unsigned ipcksum(const void *buf, size_t n, unsigned a)
432 unsigned long aa = a ^ 0xffff;
433 const unsigned char *p = buf, *l = p + n;
435 while (p < l - 1) { aa += LOAD16_B(p); p += 2; }
436 if (p < l) { aa += (unsigned)(*p) << 8; }
437 do aa = (aa & 0xffff) + (aa >> 16); while (aa >= 0x10000);
438 return (aa == 0xffff ? aa : aa ^ 0xffff);
441 /* TCP/UDP pseudoheader structure. */
443 struct in_addr ph_src, ph_dst;
448 struct in6_addr ph6_src, ph6_dst;
450 uint8_t ph6_z0, ph6_z1, ph6_z2, ph6_nxt;
455 int sk, rawicmp, rawudp;
456 uint16_t srcport, dstport;
460 static int raw_setup(void *stv, int sk, const struct param *pp)
462 struct raw_state *st = stv;
465 struct ifaddrs *ifa, *ifaa, *ifap;
467 struct icmp6_filter f6;
469 /* Check that the address is OK, and that we have the necessary raw
472 * For IPv6, also set the filter so we don't get too many useless wakeups.
474 switch (pp->a.sa.sa_family) {
476 if (rawerr) { errno = rawerr; goto fail_0; }
477 st->rawicmp = rawicmp; st->rawudp = rawudp; st->sk = sk;
478 /* IPv4 filtering is available on Linux but isn't portable. */
481 if (rawerr6) { errno = rawerr6; goto fail_0; }
482 st->rawicmp = rawicmp6; st->rawudp = rawudp6; st->sk = sk;
483 ICMP6_FILTER_SETBLOCKALL(&f6);
484 ICMP6_FILTER_SETPASS(ICMP6_PACKET_TOO_BIG, &f6);
485 ICMP6_FILTER_SETPASS(ICMP6_DST_UNREACH, &f6);
486 if (setsockopt(st->rawicmp, IPPROTO_ICMPV6, ICMP6_FILTER,
488 die(EXIT_FAILURE, "failed to set icmpv6 filter: %s",
493 errno = EPFNOSUPPORT; goto fail_0;
496 /* Initialize the sequence number. */
497 st->q = rand() & 0xffff;
499 /* Snaffle the local and remote address and port number. */
502 if (getsockname(sk, &st->me.sa, &sz))
505 /* Only now do some fiddling because Linux doesn't like port numbers in
506 * IPv6 raw destination addresses...
508 switch (pp->a.sa.sa_family) {
510 st->srcport = st->me.sin.sin_port; st->me.sin.sin_port = 0;
511 st->dstport = st->a.sin.sin_port; st->a.sin.sin_port = 0;
514 st->srcport = st->me.sin6.sin6_port; st->me.sin6.sin6_port = 0;
515 st->dstport = st->a.sin6.sin6_port; st->a.sin6.sin6_port = 0;
521 /* There isn't a portable way to force the DF flag onto a packet through
522 * UDP, or even through raw IP, unless we write the entire IP header
523 * ourselves. This is somewhat annoying, especially since we have an
524 * uphill struggle keeping track of which systems randomly expect which
525 * header fields to be presented in host byte order. Oh, well.
528 if (setsockopt(rawudp, IPPROTO_IP, IP_HDRINCL, &i, sizeof(i))) goto fail_0;
530 /* Find an upper bound on the MTU. Do two passes over the interface
531 * list. If we can find matches for our local address then use the
532 * highest one of those; otherwise do a second pass and simply take the
533 * highest MTU of any network interface.
535 if (getifaddrs(&ifaa)) goto fail_0;
536 for (i = 0; i < 2; i++) {
537 for (ifap = 0, ifa = ifaa; ifa; ifa = ifa->ifa_next) {
538 if (!(ifa->ifa_flags & IFF_UP) || !ifa->ifa_addr ||
539 ifa->ifa_addr->sa_family != st->me.sa.sa_family ||
541 !addreq((union addr *)ifa->ifa_addr, &st->me, 0)) ||
542 (i == 1 && ifap && strcmp(ifap->ifa_name, ifa->ifa_name) == 0) ||
543 strlen(ifa->ifa_name) >= sizeof(ifr.ifr_name))
546 strcpy(ifr.ifr_name, ifa->ifa_name);
547 if (ioctl(sk, SIOCGIFMTU, &ifr)) goto fail_1;
548 if (mtu < ifr.ifr_mtu) mtu = ifr.ifr_mtu;
552 if (mtu < 0) { errno = ENOTCONN; goto fail_1; }
564 static void raw_finish(void *stv) { ; }
566 static void raw_selprep(void *stv, int *maxfd, fd_set *fd_in)
567 { struct raw_state *st = stv; ADDFD(st->sk); ADDFD(st->rawicmp); }
569 static int raw_xmit(void *stv, int mtu)
571 struct raw_state *st = stv;
572 unsigned char b[65536], *p;
580 switch (st->a.sa.sa_family) {
584 /* Build the IP header. */
587 ip->ip_hl = sizeof(*ip)/4;
588 ip->ip_tos = IPTOS_RELIABILITY;
589 ip->ip_len = sane_htons(mtu);
590 STEP(st->q); ip->ip_id = htons(st->q);
591 ip->ip_off = sane_htons(0 | IP_DF);
593 ip->ip_p = IPPROTO_UDP;
595 ip->ip_src = st->me.sin.sin_addr;
596 ip->ip_dst = st->a.sin.sin_addr;
598 /* Build a UDP packet in the output buffer. */
599 udp = (struct udphdr *)(ip + 1);
600 udp->uh_sport = st->srcport;
601 udp->uh_dport = st->dstport;
602 udp->uh_ulen = htons(mtu - sizeof(*ip));
605 /* Copy the payload. */
606 p = (unsigned char *)(udp + 1);
607 memcpy(p, buf, mtu - (p - b));
609 /* Calculate the UDP checksum. */
610 ph.ph_src = ip->ip_src;
611 ph.ph_dst = ip->ip_dst;
613 ph.ph_p = IPPROTO_UDP;
614 ph.ph_len = udp->uh_ulen;
616 ck = ipcksum(&ph, sizeof(ph), ck);
617 ck = ipcksum(udp, mtu - sizeof(*ip), ck);
618 udp->uh_sum = htons(ck);
624 /* Build the IP header. */
625 ip6 = (struct ip6_hdr *)b;
626 STEP(st->q); ip6->ip6_flow = htonl(0x60000000 | st->q);
627 ip6->ip6_plen = htons(mtu - sizeof(*ip6));
628 ip6->ip6_nxt = IPPROTO_UDP;
630 ip6->ip6_src = st->me.sin6.sin6_addr;
631 ip6->ip6_dst = st->a.sin6.sin6_addr;
633 /* Build a UDP packet in the output buffer. */
634 udp = (struct udphdr *)(ip6 + 1);
635 udp->uh_sport = st->srcport;
636 udp->uh_dport = st->dstport;
637 udp->uh_ulen = htons(mtu - sizeof(*ip6));
640 /* Copy the payload. */
641 p = (unsigned char *)(udp + 1);
642 memcpy(p, buf, mtu - (p - b));
644 /* Calculate the UDP checksum. */
645 ph6.ph6_src = ip6->ip6_src;
646 ph6.ph6_dst = ip6->ip6_dst;
647 ph6.ph6_len = udp->uh_ulen;
648 ph6.ph6_z0 = ph6.ph6_z1 = ph6.ph6_z2 = 0;
649 ph6.ph6_nxt = IPPROTO_UDP;
651 ck = ipcksum(&ph6, sizeof(ph6), ck);
652 ck = ipcksum(udp, mtu - sizeof(*ip6), ck);
653 udp->uh_sum = htons(ck);
661 /* Send the whole thing off. If we're too big for the interface then we
662 * might need to trim immediately.
664 if (sendto(st->rawudp, b, mtu, 0, &st->a.sa, addrsz(&st->a)) < 0) {
665 if (errno == EMSGSIZE) return (RC_LOWER);
676 static int raw_selproc(void *stv, fd_set *fd_in, struct probestate *ps)
678 struct raw_state *st = stv;
679 unsigned char b[65536];
683 struct icmp6_hdr *icmp6;
685 const unsigned char *payload;
688 /* An ICMP packet: see what's inside. */
689 if (FD_ISSET(st->rawicmp, fd_in)) {
690 if ((n = read(st->rawicmp, b, sizeof(b))) < 0) goto fail_0;
692 switch (st->me.sa.sa_family) {
697 if (n < sizeof(*ip) || n < sizeof(4*ip->ip_hl) ||
698 ip->ip_v != 4 || ip->ip_p != IPPROTO_ICMP)
700 n -= sizeof(4*ip->ip_hl);
702 icmp = (struct icmp *)(b + 4*ip->ip_hl);
703 if (n < sizeof(*icmp) || icmp->icmp_type != ICMP_UNREACH)
705 n -= offsetof(struct icmp, icmp_ip);
708 if (n < sizeof(*ip) ||
709 ip->ip_p != IPPROTO_UDP || ip->ip_hl != sizeof(*ip)/4 ||
710 ip->ip_id != htons(st->q) ||
711 ip->ip_src.s_addr != st->me.sin.sin_addr.s_addr ||
712 ip->ip_dst.s_addr != st->a.sin.sin_addr.s_addr)
716 udp = (struct udphdr *)(ip + 1);
717 if (n < sizeof(*udp) || udp->uh_sport != st->srcport ||
718 udp->uh_dport != st->dstport)
722 payload = (const unsigned char *)(udp + 1);
723 if (!mypacketp(ps, payload, n)) goto skip_icmp;
725 if (icmp->icmp_code == ICMP_UNREACH_PORT) return (RC_HIGHER);
726 else if (icmp->icmp_code != ICMP_UNREACH_NEEDFRAG) goto skip_icmp;
727 else if (icmp->icmp_nextmtu) return (htons(icmp->icmp_nextmtu));
728 else return (RC_LOWER);
733 icmp6 = (struct icmp6_hdr *)b;
734 if (n < sizeof(*icmp6) ||
735 (icmp6->icmp6_type != ICMP6_PACKET_TOO_BIG &&
736 icmp6->icmp6_type != ICMP6_DST_UNREACH))
740 ip6 = (struct ip6_hdr *)(icmp6 + 1);
741 if (n < sizeof(*ip6) || ip6->ip6_nxt != IPPROTO_UDP ||
742 memcmp(ip6->ip6_src.s6_addr,
743 st->me.sin6.sin6_addr.s6_addr, 16) ||
744 memcmp(ip6->ip6_dst.s6_addr,
745 st->a.sin6.sin6_addr.s6_addr, 16) ||
746 (ntohl(ip6->ip6_flow)&0xffff) != st->q)
750 udp = (struct udphdr *)(ip6 + 1);
751 if (n < sizeof(*udp) || udp->uh_sport != st->srcport ||
752 udp->uh_dport != st->dstport)
756 payload = (const unsigned char *)(udp + 1);
757 if (!mypacketp(ps, payload, n)) goto skip_icmp;
759 if (icmp6->icmp6_type == ICMP6_PACKET_TOO_BIG)
760 return (ntohs(icmp6->icmp6_mtu));
761 else switch (icmp6->icmp6_code) {
762 case ICMP6_DST_UNREACH_ADMIN:
763 case ICMP6_DST_UNREACH_NOPORT:
777 /* If we got a reply to the current probe then we're good. If we got an
778 * error, or the packet's sequence number is wrong, then ignore it.
780 if (FD_ISSET(st->sk, fd_in)) {
781 if ((n = read(st->sk, b, sizeof(b))) < 0) return (RC_OK);
782 else if (mypacketp(ps, b, n)) return (RC_HIGHER);
792 static const struct probe_ops raw_ops = {
793 "raw", OPS_CHAIN, sizeof(struct raw_state),
794 raw_setup, raw_finish,
795 raw_selprep, raw_xmit, raw_selproc
799 #define OPS_CHAIN &raw_ops
803 /*----- Doing the job on Linux --------------------------------------------*/
808 # define IP_MTU 14 /* Blech! */
812 int sol, so_mtu_discover, so_mtu;
817 static int linux_setup(void *stv, int sk, const struct param *pp)
819 struct linux_state *st = stv;
823 /* Check that the address is OK. */
824 switch (pp->a.sa.sa_family) {
826 st->sol = IPPROTO_IP;
827 st->so_mtu_discover = IP_MTU_DISCOVER;
832 st->sol = IPPROTO_IPV6;
833 st->so_mtu_discover = IPV6_MTU_DISCOVER;
834 st->so_mtu = IPV6_MTU;
838 errno = EPFNOSUPPORT;
842 /* Snaffle the UDP socket. */
845 /* Turn on kernel path-MTU discovery and force DF on. */
846 i = IP_PMTUDISC_PROBE;
847 if (setsockopt(st->sk, st->sol, st->so_mtu_discover, &i, sizeof(i)))
850 /* Read the initial MTU guess back and report it. */
852 if (getsockopt(st->sk, st->sol, st->so_mtu, &mtu, &sz))
859 static void linux_finish(void *stv) { ; }
861 static void linux_selprep(void *stv, int *maxfd, fd_set *fd_in)
862 { struct linux_state *st = stv; ADDFD(st->sk); }
864 static int linux_xmit(void *stv, int mtu)
866 struct linux_state *st = stv;
868 /* Write the packet. */
869 if (write(st->sk, buf, mtu - st->hdrlen) >= 0) return (RC_OK);
870 else if (errno == EMSGSIZE) return (RC_LOWER);
871 else return (RC_FAIL);
874 static int linux_selproc(void *stv, fd_set *fd_in, struct probestate *ps)
876 struct linux_state *st = stv;
880 unsigned char b[65536];
882 /* Read an answer. If it looks like the right kind of error then report a
883 * success. This is potentially wrong, since we can't tell whether an
884 * error was delayed from an earlier probe. However, we never return
885 * RC_LOWER from this method, so the packet sizes ought to be monotonically
886 * decreasing and this won't cause trouble. Otherwise update from the
887 * kernel's idea of the right MTU.
889 if (FD_ISSET(st->sk, fd_in)) {
890 n = read(st->sk, &buf, sizeof(buf));
892 mypacketp(ps, b, n) :
893 errno == ECONNREFUSED || errno == EHOSTUNREACH)
896 if (getsockopt(st->sk, st->sol, st->so_mtu, &mtu, &sz))
903 static const struct probe_ops linux_ops = {
904 "linux", OPS_CHAIN, sizeof(struct linux_state),
905 linux_setup, linux_finish,
906 linux_selprep, linux_xmit, linux_selproc
910 #define OPS_CHAIN &linux_ops
914 /*----- Help options ------------------------------------------------------*/
916 static const struct probe_ops *probe_ops = OPS_CHAIN;
918 static void version(FILE *fp)
919 { pquis(fp, "$, TrIPE version " VERSION "\n"); }
921 static void usage(FILE *fp)
923 pquis(fp, "Usage: $ [-46v] [-H HEADER] [-m METHOD]\n\
924 [-r SECS] [-g FACTOR] [-t SECS] HOST [PORT]\n");
927 static void help(FILE *fp)
929 const struct probe_ops *ops;
938 -h, --help Show this help text.\n\
939 -V, --version Show version number.\n\
940 -u, --usage Show brief usage message.\n\
942 -4, --ipv4 Restrict to IPv4 only.\n\
943 -6, --ipv6 Restrict to IPv6 only.\n\
944 -g, --growth=FACTOR Growth factor for retransmit interval.\n\
945 -m, --method=METHOD Use METHOD to probe for MTU.\n\
946 -r, --retransmit=SECS Retransmit if no reply after SEC.\n\
947 -t, --timeout=SECS Give up expecting a reply after SECS.\n\
948 -v, --verbose Write a running commentary to stderr.\n\
949 -H, --header=HEX Packet header, in hexadecimal.\n\
953 for (ops = probe_ops; ops; ops = ops->next)
954 printf("\t%s\n", ops->name);
957 /*----- Main code ---------------------------------------------------------*/
959 int main(int argc, char *argv[])
961 struct param pp = { 0, 0.333, 3.0, 8.0, 0, OPS_CHAIN };
966 struct addrinfo aihint = { 0 }, *ailist, *ai;
967 const char *host, *svc = "7";
972 #ifdef HAVE_GETIFADDRS
973 if ((rawicmp = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0 ||
974 (rawudp = socket(PF_INET, SOCK_RAW, IPPROTO_UDP)) < 0)
976 if ((rawicmp6 = socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0 ||
977 (rawudp6 = socket(PF_INET6, SOCK_RAW, IPPROTO_RAW)) < 0)
980 if (setuid(getuid()))
984 fillbuffer(buf, sizeof(buf));
986 aihint.ai_family = AF_UNSPEC;
987 aihint.ai_protocol = IPPROTO_UDP;
988 aihint.ai_socktype = SOCK_DGRAM;
989 aihint.ai_flags = AI_ADDRCONFIG;
992 static const struct option opts[] = {
993 { "help", 0, 0, 'h' },
994 { "version", 0, 0, 'V' },
995 { "usage", 0, 0, 'u' },
996 { "ipv4", 0, 0, '4' },
997 { "ipv6", 0, 0, '6' },
998 { "header", OPTF_ARGREQ, 0, 'H' },
999 { "growth", OPTF_ARGREQ, 0, 'g' },
1000 { "method", OPTF_ARGREQ, 0, 'm' },
1001 { "retransmit", OPTF_ARGREQ, 0, 'r' },
1002 { "timeout", OPTF_ARGREQ, 0, 't' },
1003 { "verbose", 0, 0, 'v' },
1007 i = mdwopt(argc, argv, "hVu" "46H:g:m:r:t:v", opts, 0, 0, 0);
1010 case 'h': help(stdout); exit(0);
1011 case 'V': version(stdout); exit(0);
1012 case 'u': usage(stdout); exit(0);
1017 hex_decode(&hc, optarg, strlen(optarg), &d);
1018 hex_decode(&hc, 0, 0, &d);
1019 sz = d.len < 532 ? d.len : 532;
1020 memcpy(buf, d.buf, sz);
1024 case '4': aihint.ai_family = AF_INET; break;
1025 case '6': aihint.ai_family = AF_INET6; break;
1026 case 'g': pp.regr = s2f(optarg, "retransmit growth factor"); break;
1027 case 'r': pp.retx = s2f(optarg, "retransmit interval"); break;
1028 case 't': pp.timeout = s2f(optarg, "timeout"); break;
1031 for (pp.pops = OPS_CHAIN; pp.pops; pp.pops = pp.pops->next)
1032 if (strcmp(pp.pops->name, optarg) == 0) goto found_alg;
1033 die(EXIT_FAILURE, "unknown probe algorithm `%s'", optarg);
1037 case 'v': pp.f |= F_VERBOSE; break;
1044 argv += optind; argc -= optind;
1045 if ((f & f_bogus) || 1 > argc || argc > 2) {
1051 if (argv[1]) svc = argv[1];
1052 if ((err = getaddrinfo(host, svc, &aihint, &ailist)) != 0) {
1053 die(EXIT_FAILURE, "unknown host `%s' or service `%s': %s",
1054 host, svc, gai_strerror(err));
1056 for (ai = ailist; ai && !addrfamok(ai->ai_family); ai = ai->ai_next);
1057 if (!ai) die(EXIT_FAILURE, "no supported address families for `%s'", host);
1058 assert(ai->ai_addrlen <= sizeof(pp.a));
1059 memcpy(&pp.a, ai->ai_addr, ai->ai_addrlen);
1063 die(EXIT_FAILURE, "failed to discover MTU: %s", strerror(errno));
1065 if (ferror(stdout) || fflush(stdout) || fclose(stdout))
1066 die(EXIT_FAILURE, "failed to write result: %s", strerror(errno));
1070 /*----- That's all, folks -------------------------------------------------*/