/*
* tracepath.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <linux/types.h>
#include <linux/errqueue.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <resolv.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <arpa/inet.h>
#ifdef USE_IDN
#include <idna.h>
#include <locale.h>
#endif
#ifndef IP_PMTUDISC_PROBE
#define IP_PMTUDISC_PROBE 3
#endif
#define MAX_HOPS_LIMIT 255
#define MAX_HOPS_DEFAULT 30
struct hhistory
{
int hops;
struct timeval sendtime;
};
struct hhistory his[64];
int hisptr;
struct sockaddr_in target;
__u16 base_port;
int max_hops = MAX_HOPS_DEFAULT;
const int overhead = 28;
int mtu = 65535;
void *pktbuf;
int hops_to = -1;
int hops_from = -1;
int no_resolve = 0;
int show_both = 0;
#define HOST_COLUMN_SIZE 52
struct probehdr
{
__u32 ttl;
struct timeval tv;
};
void data_wait(int fd)
{
fd_set fds;
struct timeval tv;
FD_ZERO(&fds);
FD_SET(fd, &fds);
tv.tv_sec = 1;
tv.tv_usec = 0;
select(fd+1, &fds, NULL, NULL, &tv);
}
void print_host(const char *a, const char *b, int both)
{
int plen;
plen = printf("%s", a);
if (both)
plen += printf(" (%s)", b);
if (plen >= HOST_COLUMN_SIZE)
plen = HOST_COLUMN_SIZE - 1;
printf("%*s", HOST_COLUMN_SIZE - plen, "");
}
int recverr(int fd, int ttl)
{
int res;
struct probehdr rcvbuf;
char cbuf[512];
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsg;
struct sock_extended_err *e;
struct sockaddr_in addr;
struct timeval tv;
struct timeval *rettv;
int slot;
int rethops;
int sndhops;
int progress = -1;
int broken_router;
restart:
memset(&rcvbuf, -1, sizeof(rcvbuf));
iov.iov_base = &rcvbuf;
iov.iov_len = sizeof(rcvbuf);
msg.msg_name = (__u8*)&addr;
msg.msg_namelen = sizeof(addr);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_flags = 0;
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
gettimeofday(&tv, NULL);
res = recvmsg(fd, &msg, MSG_ERRQUEUE);
if (res < 0) {
if (errno == EAGAIN)
return progress;
goto restart;
}
progress = mtu;
rethops = -1;
sndhops = -1;
e = NULL;
rettv = NULL;
slot = ntohs(addr.sin_port) - base_port;
if (slot>=0 && slot < 63 && his[slot].hops) {
sndhops = his[slot].hops;
rettv = &his[slot].sendtime;
his[slot].hops = 0;
}
broken_router = 0;
if (res == sizeof(rcvbuf)) {
if (rcvbuf.ttl == 0 || rcvbuf.tv.tv_sec == 0) {
broken_router = 1;
} else {
sndhops = rcvbuf.ttl;
rettv = &rcvbuf.tv;
}
}
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == SOL_IP) {
if (cmsg->cmsg_type == IP_RECVERR) {
e = (struct sock_extended_err *) CMSG_DATA(cmsg);
} else if (cmsg->cmsg_type == IP_TTL) {
memcpy(&rethops, CMSG_DATA(cmsg), sizeof(rethops));
} else {
printf("cmsg:%d\n ", cmsg->cmsg_type);
}
}
}
if (e == NULL) {
printf("no info\n");
return 0;
}
if (e->ee_origin == SO_EE_ORIGIN_LOCAL) {
printf("%2d?: %*s ", ttl, -(HOST_COLUMN_SIZE - 1), "[LOCALHOST]");
} else if (e->ee_origin == SO_EE_ORIGIN_ICMP) {
char abuf[128];
struct sockaddr_in *sin = (struct sockaddr_in*)(e+1);
struct hostent *h = NULL;
char *idn = NULL;
inet_ntop(AF_INET, &sin->sin_addr, abuf, sizeof(abuf));
if (sndhops>0)
printf("%2d: ", sndhops);
else
printf("%2d?: ", ttl);
if (!no_resolve || show_both) {
fflush(stdout);
h = gethostbyaddr((char *) &sin->sin_addr, sizeof(sin->sin_addr), AF_INET);
}
#ifdef USE_IDN
if (h && idna_to_unicode_lzlz(h->h_name, &idn, 0) != IDNA_SUCCESS)
idn = NULL;
#endif
if (no_resolve)
print_host(abuf, h ? (idn ? idn : h->h_name) : abuf, show_both);
else
print_host(h ? (idn ? idn : h->h_name) : abuf, abuf, show_both);
#ifdef USE_IDN
free(idn);
#endif
}
if (rettv) {
int diff = (tv.tv_sec-rettv->tv_sec)*1000000+(tv.tv_usec-rettv->tv_usec);
printf("%3d.%03dms ", diff/1000, diff%1000);
if (broken_router)
printf("(This broken router returned corrupted payload) ");
}
switch (e->ee_errno) {
case ETIMEDOUT:
printf("\n");
break;
case EMSGSIZE:
printf("pmtu %d\n", e->ee_info);
mtu = e->ee_info;
progress = mtu;
break;
case ECONNREFUSED:
printf("reached\n");
hops_to = sndhops<0 ? ttl : sndhops;
hops_from = rethops;
return 0;
case EPROTO:
printf("!P\n");
return 0;
case EHOSTUNREACH:
if (e->ee_origin == SO_EE_ORIGIN_ICMP &&
e->ee_type == 11 &&
e->ee_code == 0) {
if (rethops>=0) {
if (rethops<=64)
rethops = 65-rethops;
else if (rethops<=128)
rethops = 129-rethops;
else
rethops = 256-rethops;
if (sndhops>=0 && rethops != sndhops)
printf("asymm %2d ", rethops);
else if (sndhops<0 && rethops != ttl)
printf("asymm %2d ", rethops);
}
printf("\n");
break;
}
printf("!H\n");
return 0;
case ENETUNREACH:
printf("!N\n");
return 0;
case EACCES:
printf("!A\n");
return 0;
default:
printf("\n");
errno = e->ee_errno;
perror("NET ERROR");
return 0;
}
goto restart;
}
int probe_ttl(int fd, int ttl)
{
int i;
struct probehdr *hdr = pktbuf;
memset(pktbuf, 0, mtu);
restart:
for (i=0; i<10; i++) {
int res;
hdr->ttl = ttl;
target.sin_port = htons(base_port + hisptr);
gettimeofday(&hdr->tv, NULL);
his[hisptr].hops = ttl;
his[hisptr].sendtime = hdr->tv;
if (sendto(fd, pktbuf, mtu-overhead, 0, (struct sockaddr*)&target, sizeof(target)) > 0)
break;
res = recverr(fd, ttl);
his[hisptr].hops = 0;
if (res==0)
return 0;
if (res > 0)
goto restart;
}
hisptr = (hisptr + 1)&63;
if (i<10) {
data_wait(fd);
if (recv(fd, pktbuf, mtu, MSG_DONTWAIT) > 0) {
printf("%2d?: reply received 8)\n", ttl);
return 0;
}
return recverr(fd, ttl);
}
printf("%2d: send failed\n", ttl);
return 0;
}
static void usage(void) __attribute((noreturn));
static void usage(void)
{
fprintf(stderr, "Usage: tracepath [-n] [-b] [-l <len>] [-p port] <destination>\n");
exit(-1);
}
int
main(int argc, char **argv)
{
struct hostent *he;
int fd;
int on;
int ttl;
char *p;
int ch;
#ifdef USE_IDN
int rc;
setlocale(LC_ALL, "");
#endif
while ((ch = getopt(argc, argv, "nbh?l:m:p:")) != EOF) {
switch(ch) {
case 'n':
no_resolve = 1;
break;
case 'b':
show_both = 1;
break;
case 'l':
if ((mtu = atoi(optarg)) <= overhead) {
fprintf(stderr, "Error: pktlen must be > %d and <= %d.\n",
overhead, INT_MAX);
exit(1);
}
break;
case 'm':
max_hops = atoi(optarg);
if (max_hops < 0 || max_hops > MAX_HOPS_LIMIT) {
fprintf(stderr,
"Error: max hops must be 0 .. %d (inclusive).\n",
MAX_HOPS_LIMIT);
}
break;
case 'p':
base_port = atoi(optarg);
break;
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc != 1)
usage();
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd < 0) {
perror("socket");
exit(1);
}
target.sin_family = AF_INET;
/* Backward compatiblity */
if (!base_port) {
p = strchr(argv[0], '/');
if (p) {
*p = 0;
base_port = atoi(p+1);
} else
base_port = 44444;
}
p = argv[0];
#ifdef USE_IDN
rc = idna_to_ascii_lz(argv[0], &p, 0);
if (rc != IDNA_SUCCESS) {
fprintf(stderr, "IDNA encoding failed: %s\n", idna_strerror(rc));
exit(2);
}
#endif
he = gethostbyname(p);
if (he == NULL) {
herror("gethostbyname");
exit(1);
}
#ifdef USE_IDN
free(p);
#endif
memcpy(&target.sin_addr, he->h_addr, 4);
on = IP_PMTUDISC_PROBE;
if (setsockopt(fd, SOL_IP, IP_MTU_DISCOVER, &on, sizeof(on)) &&
(on = IP_PMTUDISC_DO,
setsockopt(fd, SOL_IP, IP_MTU_DISCOVER, &on, sizeof(on)))) {
perror("IP_MTU_DISCOVER");
exit(1);
}
on = 1;
if (setsockopt(fd, SOL_IP, IP_RECVERR, &on, sizeof(on))) {
perror("IP_RECVERR");
exit(1);
}
if (setsockopt(fd, SOL_IP, IP_RECVTTL, &on, sizeof(on))) {
perror("IP_RECVTTL");
exit(1);
}
pktbuf = malloc(mtu);
if (!pktbuf) {
perror("malloc");
exit(1);
}
for (ttl = 1; ttl <= max_hops; ttl++) {
int res;
int i;
on = ttl;
if (setsockopt(fd, SOL_IP, IP_TTL, &on, sizeof(on))) {
perror("IP_TTL");
exit(1);
}
restart:
for (i=0; i<3; i++) {
int old_mtu;
old_mtu = mtu;
res = probe_ttl(fd, ttl);
if (mtu != old_mtu)
goto restart;
if (res == 0)
goto done;
if (res > 0)
break;
}
if (res < 0)
printf("%2d: no reply\n", ttl);
}
printf(" Too many hops: pmtu %d\n", mtu);
done:
printf(" Resume: pmtu %d ", mtu);
if (hops_to>=0)
printf("hops %d ", hops_to);
if (hops_from>=0)
printf("back %d ", hops_from);
printf("\n");
exit(0);
}