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3978adc44

Denys Vlasenko
Denys Vlasenko
2020-12-12
SUCCESS Duration: 149s

Subject

traceroute: fix traceroute6 -I (icmp mode)

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

networking/traceroute.c +135 -71
networking/traceroute.c+135 -71
@@ -414,9 +414,32 @@ struct globals {
waittime = 5; \
} while (0)
-#define outicmp ((struct icmp *)(outip + 1))
-#define outudp ((struct udphdr *)(outip + 1))
-
+#define outudp ((struct udphdr *)(outip + 1))
+#define outudp6 ((struct udphdr *)(((struct ip6_hdr*)outip) + 1))
+#define outicmp ((struct icmp *)(outip + 1))
+#define outicmp6 ((struct icmp *)(((struct ip6_hdr*)outip) + 1))
+/* NB: for icmp echo, IPv4 and IPv6 fields are the same size and offset:
+ * struct icmp:
+ * uint8_t icmp_type;
+ * uint8_t icmp_code;
+ * uint16_t icmp_cksum;
+ * uint16_t icmp_id;
+ * uint16_t icmp_seq;
+ * struct icmp6_hdr:
+ * uint8_t icmp6_type;
+ * uint8_t icmp6_code;
+ * uint16_t icmp6_cksum;
+ * uint16_t icmp6_id;
+ * uint16_t icmp6_seq;
+ * therefore both outicmp and outicmp6 are pointers to *IPv4* icmp struct.
+ * SIZEOF_ICMP_HDR == 8 is the same for both, as well.
+ * However, values of these pointers are not the same (since IPv6 IP header is larger),
+ * and icmp_type constants are not the same:
+ * #define ICMP_ECHO 8
+ * #define ICMP_ECHOREPLY 0
+ * #define ICMP6_ECHO_REQUEST 128
+ * #define ICMP6_ECHO_REPLY 129
+ */
static int
wait_for_reply(len_and_sockaddr *from_lsa, struct sockaddr *to, unsigned *timestamp_us, int *left_ms)
@@ -446,14 +469,16 @@ send_probe(int seq, int ttl)
{
int len, res;
void *out;
+ struct icmp *icp;
/* Payload */
#if ENABLE_TRACEROUTE6
if (dest_lsa->u.sa.sa_family == AF_INET6) {
- struct outdata6_t *pkt = (struct outdata6_t *) outdata;
+ struct outdata6_t *pkt = (void *) outdata;
pkt->ident6 = htonl(ident);
pkt->seq6 = htonl(seq);
/*gettimeofday(&pkt->tv, &tz);*/
+ icp = outicmp6;
} else
#endif
{
@@ -461,19 +486,23 @@ send_probe(int seq, int ttl)
outdata->ttl = ttl;
// UNUSED: was storing gettimeofday's result there, but never ever checked it
/*memcpy(&outdata->tv, tp, sizeof(outdata->tv));*/
-
- if (option_mask32 & OPT_USE_ICMP) {
- outicmp->icmp_seq = htons(seq);
-
- /* Always calculate checksum for icmp packets */
- outicmp->icmp_cksum = 0;
- outicmp->icmp_cksum = inet_cksum(
- outicmp,
- ((char*)outip + packlen) - (char*)outicmp
- );
- if (outicmp->icmp_cksum == 0)
- outicmp->icmp_cksum = 0xffff;
- }
+ icp = outicmp;
+ }
+ out = outdata;
+ if (option_mask32 & OPT_USE_ICMP) {
+ out = icp;
+ /*icp->icmp_type = ICMP[6]_ECHO; - already set */
+ /*icp->icmp_code = 0; - already set */
+ /*icp->icmp_id = ident; - already set */
+ icp->icmp_seq = htons(seq);
+ /* Always calculate checksum for icmp packets */
+ icp->icmp_cksum = 0;
+ icp->icmp_cksum = inet_cksum(
+ icp,
+ ((char*)outip + packlen) - (char*)icp
+ );
+ if (icp->icmp_cksum == 0)
+ icp->icmp_cksum = 0xffff;
}
//BUG! verbose is (x & OPT_VERBOSE), not a counter!
@@ -502,7 +531,6 @@ send_probe(int seq, int ttl)
}
#endif
- out = outdata;
#if ENABLE_TRACEROUTE6
if (dest_lsa->u.sa.sa_family == AF_INET6) {
res = setsockopt_int(sndsock, SOL_IPV6, IPV6_UNICAST_HOPS, ttl);
@@ -516,8 +544,6 @@ send_probe(int seq, int ttl)
if (res != 0)
bb_perror_msg_and_die("setsockopt(%s) %d", "TTL", ttl);
#endif
- if (option_mask32 & OPT_USE_ICMP)
- out = outicmp;
}
if (!(option_mask32 & OPT_USE_ICMP)) {
@@ -579,7 +605,12 @@ packet4_ok(int read_len, const struct sockaddr_in *from, int seq)
int hlen;
const struct ip *ip;
+ /* NB: reads from (AF_INET, SOCK_RAW, IPPROTO_ICMP) socket
+ * return the entire IP packet (IOW: they do not strip IP header).
+ * This differs from (AF_INET6, SOCK_RAW, IPPROTO_ICMPV6) sockets!?
+ */
ip = (struct ip *) recv_pkt;
+
hlen = ip->ip_hl << 2;
if (read_len < hlen + ICMP_MINLEN) {
#if ENABLE_FEATURE_TRACEROUTE_VERBOSE
@@ -598,9 +629,20 @@ packet4_ok(int read_len, const struct sockaddr_in *from, int seq)
if (code == ICMP_UNREACH_NEEDFRAG)
pmtu = ntohs(icp->icmp_nextmtu);
+ if ((option_mask32 & OPT_USE_ICMP)
+ && type == ICMP_ECHOREPLY
+ && icp->icmp_id == htons(ident)
+ && icp->icmp_seq == htons(seq)
+ ) {
+ /* In UDP mode, when we reach the machine, we (usually)
+ * would get "port unreachable" - in ICMP we got "echo reply".
+ * Simulate "port unreachable" for caller:
+ */
+ return ICMP_UNREACH_PORT+1;
+ }
+
if ((type == ICMP_TIMXCEED && code == ICMP_TIMXCEED_INTRANS)
|| type == ICMP_UNREACH
- || type == ICMP_ECHOREPLY
) {
const struct ip *hip;
const struct udphdr *up;
@@ -610,14 +652,6 @@ packet4_ok(int read_len, const struct sockaddr_in *from, int seq)
if (option_mask32 & OPT_USE_ICMP) {
struct icmp *hicmp;
- /* XXX */
- if (type == ICMP_ECHOREPLY
- && icp->icmp_id == htons(ident)
- && icp->icmp_seq == htons(seq)
- ) {
- return ICMP_UNREACH_PORT+1;
- }
-
hicmp = (struct icmp *)((unsigned char *)hip + hlen);
if (hlen + SIZEOF_ICMP_HDR <= read_len
&& hip->ip_p == IPPROTO_ICMP
@@ -648,6 +682,7 @@ packet4_ok(int read_len, const struct sockaddr_in *from, int seq)
printf("\n%d bytes from %s to "
"%s: icmp type %d (%s) code %d\n",
read_len, inet_ntoa(from->sin_addr),
+//BUG: inet_ntoa() returns static buf! x2 is NONO!
inet_ntoa(ip->ip_dst),
type, pr_type(type), icp->icmp_code);
for (i = 4; i < read_len; i += sizeof(*lp))
@@ -673,11 +708,27 @@ packet_ok(int read_len, len_and_sockaddr *from_lsa,
if (from_lsa->u.sa.sa_family == AF_INET)
return packet4_ok(read_len, &from_lsa->u.sin, seq);
+ /* NB: reads from (AF_INET6, SOCK_RAW, IPPROTO_ICMPV6) socket
+ * return only ICMP packet (IOW: they strip IPv6 header).
+ * This differs from (AF_INET, SOCK_RAW, IPPROTO_ICMP) sockets!?
+ */
icp = (struct icmp6_hdr *) recv_pkt;
type = icp->icmp6_type;
code = icp->icmp6_code;
+ if ((option_mask32 & OPT_USE_ICMP)
+ && type == ICMP6_ECHO_REPLY
+ && icp->icmp6_id == htons(ident)
+ && icp->icmp6_seq == htons(seq)
+ ) {
+ /* In UDP mode, when we reach the machine, we (usually)
+ * would get "port unreachable" - in ICMP we got "echo reply".
+ * Simulate "port unreachable" for caller:
+ */
+ return (ICMP6_DST_UNREACH_NOPORT << 8) + 1;
+ }
+
if ((type == ICMP6_TIME_EXCEEDED && code == ICMP6_TIME_EXCEED_TRANSIT)
|| type == ICMP6_DST_UNREACH
) {
@@ -787,8 +838,13 @@ print(int read_len, const struct sockaddr *from, const struct sockaddr *to)
if (verbose) {
char *ina = xmalloc_sockaddr2dotted_noport(to);
#if ENABLE_TRACEROUTE6
+ /* NB: reads from (AF_INET, SOCK_RAW, IPPROTO_ICMP) socket
+ * return the entire IP packet (IOW: they do not strip IP header).
+ * Reads from (AF_INET6, SOCK_RAW, IPPROTO_ICMPV6) do strip IPv6
+ * header and return only ICMP6 packet. Weird.
+ */
if (to->sa_family == AF_INET6) {
- read_len -= sizeof(struct ip6_hdr);
+ /* read_len -= sizeof(struct ip6_hdr); - WRONG! */
} else
#endif
{
@@ -844,6 +900,9 @@ common_traceroute_main(int op, char **argv)
struct sockaddr *lastaddr;
struct sockaddr *to;
+ /* Ensure the socket fds won't be 0, 1 or 2 */
+ bb_sanitize_stdio();
+
INIT_G();
op |= getopt32(argv, "^"
@@ -885,12 +944,14 @@ common_traceroute_main(int op, char **argv)
/* Process destination and optional packet size */
minpacket = sizeof(struct ip)
- + SIZEOF_ICMP_HDR
+ + sizeof(struct udphdr)
+ sizeof(struct outdata_t);
- if (!(op & OPT_USE_ICMP))
+ if (op & OPT_USE_ICMP) {
minpacket = sizeof(struct ip)
- + sizeof(struct udphdr)
+ + SIZEOF_ICMP_HDR
+ sizeof(struct outdata_t);
+ port = 0; /* on ICMP6 sockets, sendto(ipv6.nonzero_port) throws EINVAL */
+ }
#if ENABLE_TRACEROUTE6
af = AF_UNSPEC;
if (op & OPT_IPV4)
@@ -899,10 +960,15 @@ common_traceroute_main(int op, char **argv)
af = AF_INET6;
dest_lsa = xhost_and_af2sockaddr(argv[0], port, af);
af = dest_lsa->u.sa.sa_family;
- if (af == AF_INET6)
+ if (af == AF_INET6) {
minpacket = sizeof(struct ip6_hdr)
- + sizeof(struct udphdr)
- + sizeof(struct outdata6_t);
+ + sizeof(struct udphdr)
+ + sizeof(struct outdata6_t);
+ if (op & OPT_USE_ICMP)
+ minpacket = sizeof(struct ip6_hdr)
+ + SIZEOF_ICMP_HDR
+ + sizeof(struct outdata6_t);
+ }
#else
dest_lsa = xhost2sockaddr(argv[0], port);
#endif
@@ -910,13 +976,10 @@ common_traceroute_main(int op, char **argv)
if (argv[1])
packlen = xatoul_range(argv[1], minpacket, 32 * 1024);
- /* Ensure the socket fds won't be 0, 1 or 2 */
- bb_sanitize_stdio();
-
#if ENABLE_TRACEROUTE6
if (af == AF_INET6) {
xmove_fd(xsocket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6), rcvsock);
- setsockopt_1(rcvsock, SOL_IPV6, IPV6_RECVPKTINFO);
+ setsockopt_1(rcvsock, SOL_IPV6, IPV6_RECVPKTINFO); //why?
} else
#endif
{
@@ -934,7 +997,10 @@ common_traceroute_main(int op, char **argv)
if (af == AF_INET6) {
if (setsockopt_int(rcvsock, SOL_RAW, IPV6_CHECKSUM, 2) != 0)
bb_perror_msg_and_die("setsockopt(%s)", "IPV6_CHECKSUM");
- xmove_fd(xsocket(af, SOCK_DGRAM, 0), sndsock);
+ if (op & OPT_USE_ICMP)
+ xmove_fd(xsocket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6), sndsock);
+ else
+ xmove_fd(xsocket(AF_INET6, SOCK_DGRAM, 0), sndsock);
} else
#endif
{
@@ -943,6 +1009,7 @@ common_traceroute_main(int op, char **argv)
else
xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), sndsock);
}
+//TODO xmove_fd to here!
#ifdef SO_SNDBUF
if (setsockopt_SOL_SOCKET_int(sndsock, SO_SNDBUF, packlen) != 0) {
@@ -970,21 +1037,25 @@ common_traceroute_main(int op, char **argv)
ident = getpid();
if (!ENABLE_TRACEROUTE6 || af == AF_INET) {
+ outdata = (void*)(outudp + 1);
if (op & OPT_USE_ICMP) {
ident |= 0x8000;
outicmp->icmp_type = ICMP_ECHO;
+ /*outicmp->icmp_code = 0; - set by xzalloc */
outicmp->icmp_id = htons(ident);
- outdata = (struct outdata_t *)((char *)outicmp + SIZEOF_ICMP_HDR);
- } else {
- outdata = (struct outdata_t *)(outudp + 1);
+ outdata = (void*)((char *)outicmp + SIZEOF_ICMP_HDR);
}
}
#if ENABLE_TRACEROUTE6
if (af == AF_INET6) {
- outdata = (void*)((char*)outip
- + sizeof(struct ip6_hdr)
- + sizeof(struct udphdr)
- );
+ outdata = (void*)(outudp6 + 1);
+ if (op & OPT_USE_ICMP) {
+ ident |= 0x8000;
+ outicmp6->icmp_type = ICMP6_ECHO_REQUEST;
+ /*outicmp->icmp_code = 0; - set by xzalloc */
+ outicmp6->icmp_id = htons(ident);
+ outdata = (void*)((char *)outicmp6 + SIZEOF_ICMP_HDR);
+ }
}
#endif
@@ -1013,26 +1084,16 @@ common_traceroute_main(int op, char **argv)
//TODO: why we don't do it for IPv4?
len_and_sockaddr *source_lsa;
- int probe_fd = xsocket(af, SOCK_DGRAM, 0);
- if (op & OPT_DEVICE)
- setsockopt_bindtodevice(probe_fd, device);
- set_nport(&dest_lsa->u.sa, htons(1025));
- /* dummy connect. makes kernel pick source IP (and port) */
- xconnect(probe_fd, &dest_lsa->u.sa, dest_lsa->len);
set_nport(&dest_lsa->u.sa, htons(port));
-
- /* read IP and port */
- source_lsa = get_sock_lsa(probe_fd);
+ /* Connect makes kernel pick source IP and port */
+ xconnect(sndsock, &dest_lsa->u.sa, dest_lsa->len);
+ /* Read IP and port */
+ source_lsa = get_sock_lsa(sndsock);
if (source_lsa == NULL)
bb_simple_error_msg_and_die("can't get probe addr");
-
- close(probe_fd);
-
- /* bind our sockets to this IP (but not port) */
+ /* bind our recv socket to this IP (but not port) */
set_nport(&source_lsa->u.sa, 0);
- xbind(sndsock, &source_lsa->u.sa, source_lsa->len);
xbind(rcvsock, &source_lsa->u.sa, source_lsa->len);
-
free(source_lsa);
}
#endif
@@ -1067,10 +1128,9 @@ common_traceroute_main(int op, char **argv)
unsigned t1;
unsigned t2;
int left_ms;
- struct ip *ip;
fflush_all();
- if (probe != 0 && pausemsecs > 0)
+ if (probe != 0)
msleep(pausemsecs);
send_probe(++seq, ttl);
@@ -1099,15 +1159,18 @@ common_traceroute_main(int op, char **argv)
}
print_delta_ms(t1, t2);
- ip = (struct ip *)recv_pkt;
- if (from_lsa->u.sa.sa_family == AF_INET)
- if (op & OPT_TTL_FLAG)
+ if (from_lsa->u.sa.sa_family == AF_INET) {
+ if (op & OPT_TTL_FLAG) {
+ struct ip *ip = (struct ip *)recv_pkt;
printf(" (%d)", ip->ip_ttl);
+ }
+ }
- /* time exceeded in transit */
+ /* Got a "time exceeded in transit" icmp message? */
if (icmp_code == -1)
break;
+
icmp_code--;
switch (icmp_code) {
#if ENABLE_TRACEROUTE6
@@ -1115,12 +1178,13 @@ common_traceroute_main(int op, char **argv)
got_there = 1;
break;
#endif
- case ICMP_UNREACH_PORT:
+ case ICMP_UNREACH_PORT: {
+ struct ip *ip = (struct ip *)recv_pkt;
if (ip->ip_ttl <= 1)
printf(" !");
got_there = 1;
break;
-
+ }
case ICMP_UNREACH_NET:
#if ENABLE_TRACEROUTE6 && (ICMP6_DST_UNREACH_NOROUTE != ICMP_UNREACH_NET)
case ICMP6_DST_UNREACH_NOROUTE << 8: