* 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>
*/
#define _GNU_SOURCE
#include <assert.h>
#include <arpa/inet.h>
#include <errno.h>
#include <limits.h>
#include <netdb.h>
#include <netinet/in.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <time.h>
#include <unistd.h>
* Keep linux/ includes after standard headers.
* https://github.com/iputils/iputils/issues/168
*/
#include <linux/errqueue.h>
#include <linux/icmp.h>
#include <linux/icmpv6.h>
#include <linux/types.h>
#include "iputils_common.h"
#ifdef USE_IDN
# define getnameinfo_flags NI_IDN
#else
# define getnameinfo_flags 0
#endif
enum {
MAX_PROBES = 10,
MAX_HOPS_DEFAULT = 30,
MAX_HOPS_LIMIT = 255,
HOST_COLUMN_SIZE = 52,
HIS_ARRAY_SIZE = 64,
DEFAULT_OVERHEAD_IPV4 = 28,
DEFAULT_OVERHEAD_IPV6 = 48,
DEFAULT_MTU_IPV4 = 65535,
DEFAULT_MTU_IPV6 = 128000,
DEFAULT_BASEPORT = 44444,
ANCILLARY_DATA_LEN = 512,
};
struct hhistory {
int hops;
struct timespec sendtime;
};
struct probehdr {
uint32_t ttl;
struct timespec ts;
};
struct run_state {
struct hhistory his[HIS_ARRAY_SIZE];
int hisptr;
struct sockaddr_storage target;
struct addrinfo *ai;
int socket_fd;
socklen_t targetlen;
uint16_t base_port;
uint8_t ttl;
int max_hops;
int overhead;
int mtu;
void *pktbuf;
int hops_to;
int hops_from;
unsigned int
no_resolve:1,
show_both:1,
mapped:1;
};
* All includes, definitions, struct declarations, and global variables are
* above. After this comment all you can find is functions.
*/
static void data_wait(struct run_state const *const ctl)
{
fd_set fds;
struct timeval tv = {
.tv_sec = 1,
.tv_usec = 0
};
FD_ZERO(&fds);
FD_SET(ctl->socket_fd, &fds);
select(ctl->socket_fd + 1, &fds, NULL, NULL, &tv);
}
static void print_host(struct run_state const *const ctl, char const *const a,
char const *const b)
{
int plen;
plen = printf("%s", a);
if (ctl->show_both)
plen += printf(" (%s)", b);
if (plen >= HOST_COLUMN_SIZE)
plen = HOST_COLUMN_SIZE - 1;
printf("%*s", HOST_COLUMN_SIZE - plen, "");
}
static int recverr(struct run_state *const ctl)
{
ssize_t recv_size;
struct probehdr rcvbuf;
char cbuf[ANCILLARY_DATA_LEN];
struct cmsghdr *cmsg;
struct sock_extended_err *e;
struct sockaddr_storage addr;
struct timespec ts;
struct timespec *retts;
int slot = 0;
int rethops;
int sndhops;
int progress = -1;
int broken_router;
char hnamebuf[NI_MAXHOST] = "";
struct iovec iov = {
.iov_base = &rcvbuf,
.iov_len = sizeof(rcvbuf)
};
struct msghdr msg;
const struct msghdr reset = {
.msg_name = (uint8_t *)&addr,
.msg_namelen = sizeof(addr),
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = cbuf,
.msg_controllen = sizeof(cbuf),
0
};
restart:
memset(&rcvbuf, -1, sizeof(rcvbuf));
msg = reset;
clock_gettime(CLOCK_MONOTONIC, &ts);
recv_size = recvmsg(ctl->socket_fd, &msg, MSG_ERRQUEUE);
if (recv_size < 0) {
if (errno == EAGAIN)
return progress;
goto restart;
}
progress = ctl->mtu;
rethops = -1;
sndhops = -1;
e = NULL;
retts = NULL;
broken_router = 0;
slot = -ctl->base_port;
switch (ctl->ai->ai_family) {
case AF_INET6:
slot += ntohs(((struct sockaddr_in6 *)&addr)->sin6_port);
break;
case AF_INET:
slot += ntohs(((struct sockaddr_in *)&addr)->sin_port);
break;
}
if (slot >= 0 && slot < (HIS_ARRAY_SIZE - 1) && ctl->his[slot].hops) {
sndhops = ctl->his[slot].hops;
retts = &ctl->his[slot].sendtime;
ctl->his[slot].hops = 0;
}
if (recv_size == sizeof(rcvbuf)) {
if (rcvbuf.ttl == 0 || (rcvbuf.ts.tv_sec == 0 && rcvbuf.ts.tv_nsec == 0))
broken_router = 1;
else {
sndhops = rcvbuf.ttl;
retts = &rcvbuf.ts;
}
}
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
switch (cmsg->cmsg_level) {
case SOL_IPV6:
switch (cmsg->cmsg_type) {
case IPV6_RECVERR:
e = (struct sock_extended_err *)CMSG_DATA(cmsg);
break;
case IPV6_HOPLIMIT:
#ifdef IPV6_2292HOPLIMIT
case IPV6_2292HOPLIMIT:
#endif
memcpy(&rethops, CMSG_DATA(cmsg), sizeof(rethops));
break;
default:
printf(_("cmsg6:%d\n "), cmsg->cmsg_type);
}
break;
case SOL_IP:
switch (cmsg->cmsg_type) {
case IP_RECVERR:
e = (struct sock_extended_err *)CMSG_DATA(cmsg);
break;
case IP_TTL:
rethops = *(uint8_t *)CMSG_DATA(cmsg);
break;
default:
printf(_("cmsg4:%d\n "), cmsg->cmsg_type);
}
}
}
if (e == NULL) {
printf(_("no info\n"));
return 0;
}
if (e->ee_origin == SO_EE_ORIGIN_LOCAL)
printf("%2d?: %-32s ", ctl->ttl, _("[LOCALHOST]"));
else if (e->ee_origin == SO_EE_ORIGIN_ICMP6 ||
e->ee_origin == SO_EE_ORIGIN_ICMP) {
char abuf[NI_MAXHOST];
struct sockaddr *sa = (struct sockaddr *)(e + 1);
socklen_t salen;
if (sndhops > 0)
printf("%2d: ", sndhops);
else
printf("%2d?: ", ctl->ttl);
switch (sa->sa_family) {
case AF_INET6:
salen = sizeof(struct sockaddr_in6);
break;
case AF_INET:
salen = sizeof(struct sockaddr_in);
break;
default:
salen = 0;
}
if (ctl->no_resolve || ctl->show_both) {
if (getnameinfo(sa, salen, abuf, sizeof(abuf), NULL, 0,
NI_NUMERICHOST))
strcpy(abuf, "???");
} else
abuf[0] = 0;
if (!ctl->no_resolve || ctl->show_both) {
fflush(stdout);
if (getnameinfo(sa, salen, hnamebuf, sizeof hnamebuf, NULL, 0,
getnameinfo_flags))
strcpy(hnamebuf, "???");
} else
hnamebuf[0] = 0;
if (ctl->no_resolve)
print_host(ctl, abuf, hnamebuf);
else
print_host(ctl, hnamebuf, abuf);
}
if (retts) {
struct timespec res;
timespecsub(&ts, retts, &res);
printf(_("%3lld.%03ldms "), (long long int)res.tv_sec * 1000
+ res.tv_nsec / 1000000, (res.tv_nsec % 1000000) / 1000);
if (broken_router)
printf(_("(This broken router returned corrupted payload) "));
}
if (rethops <= 64)
rethops = 65 - rethops;
else if (rethops <= 128)
rethops = 129 - rethops;
else
rethops = 256 - rethops;
switch (e->ee_errno) {
case ETIMEDOUT:
printf("\n");
break;
case EMSGSIZE:
printf(_("pmtu %d\n"), e->ee_info);
ctl->mtu = e->ee_info;
progress = ctl->mtu;
break;
case ECONNREFUSED:
printf(_("reached\n"));
ctl->hops_to = sndhops < 0 ? ctl->ttl : sndhops;
ctl->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 == ICMP_TIME_EXCEEDED &&
e->ee_code == ICMP_EXC_TTL) ||
(e->ee_origin == SO_EE_ORIGIN_ICMP6 &&
e->ee_type == ICMPV6_TIME_EXCEED &&
e->ee_code == ICMPV6_EXC_HOPLIMIT)) {
if (rethops >= 0) {
if ((sndhops >= 0 && rethops != sndhops) ||
(sndhops < 0 && rethops != ctl->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");
error(0, e->ee_errno, _("NET ERROR"));
return 0;
}
goto restart;
}
static int probe_ttl(struct run_state *const ctl)
{
int i;
struct probehdr *hdr = ctl->pktbuf;
memset(ctl->pktbuf, 0, ctl->mtu);
restart:
for (i = 0; i < MAX_PROBES; i++) {
int res;
hdr->ttl = ctl->ttl;
switch (ctl->ai->ai_family) {
case AF_INET6:
((struct sockaddr_in6 *)&ctl->target)->sin6_port =
htons(ctl->base_port + ctl->hisptr);
break;
case AF_INET:
((struct sockaddr_in *)&ctl->target)->sin_port =
htons(ctl->base_port + ctl->hisptr);
break;
}
clock_gettime(CLOCK_MONOTONIC, &hdr->ts);
ctl->his[ctl->hisptr].hops = ctl->ttl;
ctl->his[ctl->hisptr].sendtime = hdr->ts;
if (sendto(ctl->socket_fd, ctl->pktbuf, ctl->mtu - ctl->overhead, 0,
(struct sockaddr *)&ctl->target, ctl->targetlen) > 0)
break;
res = recverr(ctl);
ctl->his[ctl->hisptr].hops = 0;
if (res == 0)
return 0;
if (res > 0)
goto restart;
}
ctl->hisptr = (ctl->hisptr + 1) & (HIS_ARRAY_SIZE - 1);
if (i < MAX_PROBES) {
data_wait(ctl);
if (recv(ctl->socket_fd, ctl->pktbuf, ctl->mtu, MSG_DONTWAIT) > 0) {
printf(_("%2d?: reply received 8)\n"), ctl->ttl);
return 0;
}
return recverr(ctl);
}
printf(_("%2d: send failed\n"), ctl->ttl);
return 0;
}
static void usage(void)
{
fprintf(stderr, _(
"\nUsage\n"
" tracepath [options] <destination>\n"
"\nOptions:\n"
" -4 use IPv4\n"
" -6 use IPv6\n"
" -b print both name and IP\n"
" -l <length> use packet <length>\n"
" -m <hops> use maximum <hops>\n"
" -n no reverse DNS name resolution\n"
" -p <port> use destination <port>\n"
" -V print version and exit\n"
" <destination> DNS name or IP address\n"
"\nFor more details see tracepath(8).\n"));
exit(-1);
}
int main(int argc, char **argv)
{
struct run_state ctl = {
.max_hops = MAX_HOPS_DEFAULT,
.hops_to = -1,
.hops_from = -1,
0
};
struct addrinfo hints = {
.ai_family = AF_UNSPEC,
.ai_socktype = SOCK_DGRAM,
.ai_protocol = IPPROTO_UDP,
#ifdef USE_IDN
.ai_flags = AI_IDN | AI_CANONNAME,
#endif
};
struct addrinfo *result;
int ch;
int status;
int on;
char *p;
char pbuf[NI_MAXSERV];
atexit(close_stdout);
#if defined(USE_IDN) || defined(ENABLE_NLS)
setlocale(LC_ALL, "");
#ifdef ENABLE_NLS
bindtextdomain (PACKAGE_NAME, LOCALEDIR);
textdomain (PACKAGE_NAME);
#endif
#endif
if (argv[0][strlen(argv[0]) - 1] == '4')
hints.ai_family = AF_INET;
else if (argv[0][strlen(argv[0]) - 1] == '6')
hints.ai_family = AF_INET6;
while ((ch = getopt(argc, argv, "46nbh?l:m:p:V")) != EOF) {
switch (ch) {
case '4':
if (hints.ai_family == AF_INET6)
error(2, 0, _("Only one -4 or -6 option may be specified"));
hints.ai_family = AF_INET;
break;
case '6':
if (hints.ai_family == AF_INET)
error(2, 0, _("Only one -4 or -6 option may be specified"));
hints.ai_family = AF_INET6;
break;
case 'n':
ctl.no_resolve = 1;
break;
case 'b':
ctl.show_both = 1;
break;
case 'l':
ctl.mtu = strtol_or_err(optarg, _("invalid argument"), 0, INT_MAX);
break;
case 'm':
ctl.max_hops = strtol_or_err(optarg, _("invalid argument"), 0, MAX_HOPS_LIMIT);
break;
case 'p':
ctl.base_port = strtol_or_err(optarg, _("invalid argument"), 0, UINT16_MAX);
break;
case 'V':
printf(IPUTILS_VERSION("tracepath"));
print_config();
return 0;
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc != 1)
usage();
if (!ctl.base_port) {
p = strchr(argv[0], '/');
if (p) {
*p = 0;
ctl.base_port = strtol_or_err(p + 1, _("invalid argument"), 0, UINT16_MAX);
} else
ctl.base_port = DEFAULT_BASEPORT;
}
sprintf(pbuf, "%u", ctl.base_port);
status = getaddrinfo(argv[0], pbuf, &hints, &result);
if (status || !result) {
error(1, 0, "%s: %s", argv[0], gai_strerror(status));
abort();
}
for (ctl.ai = result; ctl.ai; ctl.ai = ctl.ai->ai_next) {
assert(ctl.ai != NULL);
if (ctl.ai->ai_family != AF_INET6 && ctl.ai->ai_family != AF_INET)
continue;
ctl.socket_fd = socket(ctl.ai->ai_family, ctl.ai->ai_socktype, ctl.ai->ai_protocol);
if (ctl.socket_fd < 0)
continue;
memcpy(&ctl.target, ctl.ai->ai_addr, ctl.ai->ai_addrlen);
ctl.targetlen = ctl.ai->ai_addrlen;
break;
}
if (ctl.socket_fd < 0)
error(1, errno, "socket/connect");
switch (ctl.ai->ai_family) {
case AF_INET6:
ctl.overhead = DEFAULT_OVERHEAD_IPV6;
if (!ctl.mtu)
ctl.mtu = DEFAULT_MTU_IPV6;
if (ctl.mtu <= ctl.overhead)
goto pktlen_error;
on = IPV6_PMTUDISC_PROBE;
if (setsockopt(ctl.socket_fd, SOL_IPV6, IPV6_MTU_DISCOVER, &on, sizeof(on)) &&
(on = IPV6_PMTUDISC_DO, setsockopt(ctl.socket_fd, SOL_IPV6,
IPV6_MTU_DISCOVER, &on, sizeof(on))))
error(1, errno, "IPV6_MTU_DISCOVER");
on = 1;
if (setsockopt(ctl.socket_fd, SOL_IPV6, IPV6_RECVERR, &on, sizeof(on)))
error(1, errno, "IPV6_RECVERR");
if (setsockopt(ctl.socket_fd, SOL_IPV6, IPV6_HOPLIMIT, &on, sizeof(on))
#ifdef IPV6_RECVHOPLIMIT
&& setsockopt(ctl.socket_fd, SOL_IPV6, IPV6_2292HOPLIMIT, &on, sizeof(on))
#endif
)
error(1, errno, "IPV6_HOPLIMIT");
if (!IN6_IS_ADDR_V4MAPPED(&(((struct sockaddr_in6 *)&ctl.target)->sin6_addr)))
break;
ctl.mapped = 1;
case AF_INET:
ctl.overhead = DEFAULT_OVERHEAD_IPV4;
if (!ctl.mtu)
ctl.mtu = DEFAULT_MTU_IPV4;
if (ctl.mtu <= ctl.overhead)
goto pktlen_error;
on = IP_PMTUDISC_PROBE;
if (setsockopt(ctl.socket_fd, SOL_IP, IP_MTU_DISCOVER, &on, sizeof(on)))
error(1, errno, "IP_MTU_DISCOVER");
on = 1;
if (setsockopt(ctl.socket_fd, SOL_IP, IP_RECVERR, &on, sizeof(on)))
error(1, errno, "IP_RECVERR");
if (setsockopt(ctl.socket_fd, SOL_IP, IP_RECVTTL, &on, sizeof(on)))
error(1, errno, "IP_RECVTTL");
}
ctl.pktbuf = malloc(ctl.mtu);
if (!ctl.pktbuf)
error(1, errno, "malloc");
for (ctl.ttl = 1; ctl.ttl <= ctl.max_hops; ctl.ttl++) {
int res = -1;
int i;
on = ctl.ttl;
switch (ctl.ai->ai_family) {
case AF_INET6:
if (setsockopt(ctl.socket_fd, SOL_IPV6, IPV6_UNICAST_HOPS, &on, sizeof(on)))
error(1, errno, "IPV6_UNICAST_HOPS");
if (!ctl.mapped)
break;
case AF_INET:
if (setsockopt(ctl.socket_fd, SOL_IP, IP_TTL, &on, sizeof(on)))
error(1, errno, "IP_TTL");
}
restart:
for (i = 0; i < 3; i++) {
int old_mtu;
old_mtu = ctl.mtu;
res = probe_ttl(&ctl);
if (ctl.mtu != old_mtu)
goto restart;
if (res == 0)
goto done;
if (res > 0)
break;
}
if (res < 0)
printf(_("%2d: no reply\n"), ctl.ttl);
}
printf(" Too many hops: pmtu %d\n", ctl.mtu);
done:
freeaddrinfo(result);
printf(_(" Resume: pmtu %d "), ctl.mtu);
if (ctl.hops_to >= 0)
printf(_("hops %d "), ctl.hops_to);
if (ctl.hops_from >= 0)
printf(_("back %d "), ctl.hops_from);
printf("\n");
exit(0);
pktlen_error:
error(1, 0, _("pktlen must be within: %d < value <= %d"), ctl.overhead, INT_MAX);
}