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authorDenys Vlasenko <vda.linux@googlemail.com>2011-05-05 00:31:30 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2011-05-05 00:31:30 (GMT)
commita348b4557d3d0af411135c23448a2c5a7cd82982 (patch)
tree84eecc099d0705991939fed91c278ce8b65e350d
parentd3e4be3ccb1506cfabecc4c2f0baeb07fdd06723 (diff)
downloadbusybox-a348b4557d3d0af411135c23448a2c5a7cd82982.tar.gz
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traceroute: properly reduce poll timeout
This removes the problem where during the time we wait to declare a target as unresponsive we receive an unrelated ICMP packet. If there is enough traffic, this can make traceroute hang as it never declares the target as unresponsive. function old new delta common_traceroute_main 4196 4261 +65 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/traceroute.c61
1 files changed, 37 insertions, 24 deletions
diff --git a/networking/traceroute.c b/networking/traceroute.c
index 96f9d34..85181ab 100644
--- a/networking/traceroute.c
+++ b/networking/traceroute.c
@@ -398,18 +398,23 @@ static len_and_sockaddr* dup_sockaddr(const len_and_sockaddr *lsa)
static int
-wait_for_reply(len_and_sockaddr *from_lsa, struct sockaddr *to)
+wait_for_reply(len_and_sockaddr *from_lsa, struct sockaddr *to, unsigned *timestamp_us, int *left_ms)
{
struct pollfd pfd[1];
int read_len = 0;
pfd[0].fd = rcvsock;
pfd[0].events = POLLIN;
- if (safe_poll(pfd, 1, waittime * 1000) > 0) {
+ if (*left_ms >= 0 && safe_poll(pfd, 1, *left_ms) > 0) {
+ unsigned t;
+
read_len = recv_from_to(rcvsock,
recv_pkt, sizeof(recv_pkt),
- /*flags:*/ 0,
+ /*flags:*/ MSG_DONTWAIT,
&from_lsa->u.sa, to, from_lsa->len);
+ t = monotonic_us();
+ *left_ms -= (t - *timestamp_us) / 1000;
+ *timestamp_us = t;
}
return read_len;
@@ -730,7 +735,7 @@ packet_ok(int read_len, len_and_sockaddr *from_lsa,
type, pr_type(type), icp->icmp6_code);
read_len -= sizeof(struct icmp6_hdr);
- for (i = 0; i < read_len ; i++) {
+ for (i = 0; i < read_len; i++) {
if (i % 16 == 0)
printf("%04x:", i);
if (i % 4 == 0)
@@ -819,7 +824,6 @@ print_delta_ms(unsigned t1p, unsigned t2p)
static int
common_traceroute_main(int op, char **argv)
{
- int i;
int minpacket;
int tos = 0;
int max_ttl = 30;
@@ -973,6 +977,7 @@ common_traceroute_main(int op, char **argv)
#if ENABLE_FEATURE_TRACEROUTE_SOURCE_ROUTE && defined IP_OPTIONS
if (lsrr > 0) {
unsigned char optlist[MAX_IPOPTLEN];
+ unsigned size;
/* final hop */
gwlist[lsrr] = dest_lsa->u.sin.sin_addr.s_addr;
@@ -982,14 +987,14 @@ common_traceroute_main(int op, char **argv)
optlist[0] = IPOPT_NOP;
/* loose source route option */
optlist[1] = IPOPT_LSRR;
- i = lsrr * sizeof(gwlist[0]);
- optlist[2] = i + 3;
+ size = lsrr * sizeof(gwlist[0]);
+ optlist[2] = size + 3;
/* pointer to LSRR addresses */
optlist[3] = IPOPT_MINOFF;
- memcpy(optlist + 4, gwlist, i);
+ memcpy(optlist + 4, gwlist, size);
if (setsockopt(sndsock, IPPROTO_IP, IP_OPTIONS,
- (char *)optlist, i + sizeof(gwlist[0])) < 0) {
+ (char *)optlist, size + sizeof(gwlist[0])) < 0) {
bb_perror_msg_and_die("IP_OPTIONS");
}
}
@@ -1103,28 +1108,34 @@ common_traceroute_main(int op, char **argv)
int unreachable = 0; /* counter */
int gotlastaddr = 0; /* flags */
int got_there = 0;
- int first = 1;
printf("%2d", ttl);
for (probe = 0; probe < nprobes; ++probe) {
int read_len;
unsigned t1;
unsigned t2;
+ int left_ms;
struct ip *ip;
- if (!first && pausemsecs > 0)
- usleep(pausemsecs * 1000);
fflush_all();
+ if (probe != 0 && pausemsecs > 0)
+ usleep(pausemsecs * 1000);
- t1 = monotonic_us();
send_probe(++seq, ttl);
+ t2 = t1 = monotonic_us();
+
+ left_ms = waittime * 1000;
+ while ((read_len = wait_for_reply(from_lsa, to, &t2, &left_ms)) != 0) {
+ int icmp_code;
+
+ /* Recv'ed a packet, or read error */
+ /* t2 = monotonic_us() - set by wait_for_reply */
- first = 0;
- while ((read_len = wait_for_reply(from_lsa, to)) != 0) {
- t2 = monotonic_us();
- i = packet_ok(read_len, from_lsa, to, seq);
+ if (read_len < 0)
+ continue;
+ icmp_code = packet_ok(read_len, from_lsa, to, seq);
/* Skip short packet */
- if (i == 0)
+ if (icmp_code == 0)
continue;
if (!gotlastaddr
@@ -1143,10 +1154,10 @@ common_traceroute_main(int op, char **argv)
printf(" (%d)", ip->ip_ttl);
/* time exceeded in transit */
- if (i == -1)
+ if (icmp_code == -1)
break;
- i--;
- switch (i) {
+ icmp_code--;
+ switch (icmp_code) {
#if ENABLE_TRACEROUTE6
case ICMP6_DST_UNREACH_NOPORT << 8:
got_there = 1;
@@ -1219,16 +1230,18 @@ common_traceroute_main(int op, char **argv)
++unreachable;
break;
default:
- printf(" !<%d>", i);
+ printf(" !<%d>", icmp_code);
++unreachable;
break;
}
break;
- }
+ } /* while (wait and read a packet) */
+
/* there was no packet at all? */
if (read_len == 0)
printf(" *");
- }
+ } /* for (nprobes) */
+
bb_putchar('\n');
if (got_there
|| (unreachable > 0 && unreachable >= nprobes - 1)