Date: Mon, 09 Feb 2026 10:00:14 +0000 From: Eugene Grosbein <eugen@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 60a6ebaf7371 - main - traceroute: graceful recover after networking errors with as_server Message-ID: <6989b02e.1c92d.ca70ad2@gitrepo.freebsd.org>
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The branch main has been updated by eugen: URL: https://cgit.FreeBSD.org/src/commit/?id=60a6ebaf73719ef7aa15768c3906626fb106b2b3 commit 60a6ebaf73719ef7aa15768c3906626fb106b2b3 Author: Eugene Grosbein <eugen@FreeBSD.org> AuthorDate: 2026-02-09 09:47:01 +0000 Commit: Eugene Grosbein <eugen@FreeBSD.org> CommitDate: 2026-02-09 10:00:10 +0000 traceroute: graceful recover after networking errors with as_server Currentlu, the traceroute[6] utility does not check for possible networking errors while talking to as_server in case of "traceroute -a". Meantime, there is a common case when trace is long and it has many non-responding hops (shown as '* * *'), so as_server aborts our connection, hence no AS numbers shown for the rest of trace. Somewhat artifical way to reproduce the problem: traceroute to 57.144.244.1 (57.144.244.1), 80 hops max, 48 byte packets 5 [AS174] be2950.ccr42.fra05.atlas.cogentco.com (154.54.72.42) 74.277 ms 9.605 ms 9.599 ms 6 [AS174] 149.11.228.19 (149.11.228.19) 9.506 ms 9.466 ms 9.420 ms 7 [AS33182] po172.asw02.fra5.tfbnw.net (129.134.108.146) 9.725 ms 9.874 ms 9.696 ms 8 [AS32934] psw04.fra5.tfbnw.net (157.240.59.85) 8.718 ms 8.691 ms 8.618 ms 9 * * * 10 [AS0] edge-star-mini-shv-01-fra5.facebook.com (57.144.244.1) 9.747 ms 9.815 ms 9.699 ms Note what due to increased timeout (-w10) we get [AS0] for 10th hop because as_server closed our connection. Same problem occurs with default -w3 when there are lots of '* * *' hops in a trace. Fix it with some additional error checking and a reconnection. This patch was in my use for many years and after traceroute(8) moved from contrib/ to usr.sbin/ it's nice to have it in the tree. MFC after: 2 weeks --- usr.sbin/traceroute/as.c | 24 ++++++++++++++++++++---- usr.sbin/traceroute/as.h | 2 +- usr.sbin/traceroute/traceroute.c | 21 +++++++++++++++++++-- usr.sbin/traceroute6/traceroute6.c | 23 +++++++++++++++++++++-- 4 files changed, 61 insertions(+), 9 deletions(-) diff --git a/usr.sbin/traceroute/as.c b/usr.sbin/traceroute/as.c index 7fb952ed3da1..512f1dd6f14c 100644 --- a/usr.sbin/traceroute/as.c +++ b/usr.sbin/traceroute/as.c @@ -118,7 +118,7 @@ as_setup(const char *server) } unsigned int -as_lookup(void *_asn, char *addr, sa_family_t family) +as_lookup(void *_asn, char *addr, sa_family_t family, int *status) { struct aslookup *asn = _asn; char buf[1024]; @@ -128,8 +128,17 @@ as_lookup(void *_asn, char *addr, sa_family_t family) as = 0; rc = dlen = 0; plen = (family == AF_INET6) ? 128 : 32; - (void)fprintf(asn->as_f, "!r%s/%d,l\n", addr, plen); - (void)fflush(asn->as_f); + *status = fprintf(asn->as_f, "!r%s/%d,l\n", addr, plen); + if (*status < 0) { + *status = errno; + return 0; + } + *status = fflush(asn->as_f); + if (*status == EOF) { + *status = errno; + return 0; + } + *status = 0; #ifdef AS_DEBUG_FILE if (asn->as_debug) { @@ -138,7 +147,14 @@ as_lookup(void *_asn, char *addr, sa_family_t family) } #endif /* AS_DEBUG_FILE */ - while (fgets(buf, sizeof(buf), asn->as_f) != NULL) { + while (1) { + if (fgets(buf, sizeof(buf), asn->as_f) == NULL) { + if(feof(asn->as_f) || ferror(asn->as_f)) { + *status = EIO; + return 0; + } + break; + } buf[sizeof(buf) - 1] = '\0'; #ifdef AS_DEBUG_FILE diff --git a/usr.sbin/traceroute/as.h b/usr.sbin/traceroute/as.h index f5a5dae2acec..ac61bbab4786 100644 --- a/usr.sbin/traceroute/as.h +++ b/usr.sbin/traceroute/as.h @@ -30,5 +30,5 @@ */ void *as_setup(const char *); -unsigned int as_lookup(void *, char *, sa_family_t); +unsigned int as_lookup(void *, char *, sa_family_t, int *); void as_shutdown(void *); diff --git a/usr.sbin/traceroute/traceroute.c b/usr.sbin/traceroute/traceroute.c index 1297d3402ebd..be14c40b8d7b 100644 --- a/usr.sbin/traceroute/traceroute.c +++ b/usr.sbin/traceroute/traceroute.c @@ -1653,6 +1653,7 @@ print(register u_char *buf, register int cc, register struct sockaddr_in *from) { register struct ip *ip; register int hlen; + int as, status; char addr[INET_ADDRSTRLEN]; ip = (struct ip *) buf; @@ -1661,8 +1662,24 @@ print(register u_char *buf, register int cc, register struct sockaddr_in *from) strlcpy(addr, inet_ntoa(from->sin_addr), sizeof(addr)); - if (as_path) - Printf(" [AS%u]", as_lookup(asn, addr, AF_INET)); + while(as_path) { + as = as_lookup(asn, addr, AF_INET, &status); + if (status) { + as_shutdown(asn); + asn = as_setup(as_server); + if (asn == NULL) { + Fprintf(stderr, "%s: as_setup failed, AS# lookups" + " disabled\n", prog); + (void)fflush(stderr); + as_path = 0; + break; + } + else + continue; + } + Printf(" [AS%u]", as); + break; + } if (nflag) Printf(" %s", addr); diff --git a/usr.sbin/traceroute6/traceroute6.c b/usr.sbin/traceroute6/traceroute6.c index 173e97c13bb3..eb6086706f9f 100644 --- a/usr.sbin/traceroute6/traceroute6.c +++ b/usr.sbin/traceroute6/traceroute6.c @@ -894,6 +894,8 @@ main(int argc, char *argv[]) as_path = 0; } } + if (as_path) + signal(SIGPIPE, SIG_IGN); /* * Message to users @@ -1577,13 +1579,30 @@ void print(struct msghdr *mhdr, int cc) { struct sockaddr_in6 *from = (struct sockaddr_in6 *)mhdr->msg_name; + int as, status; char hbuf[NI_MAXHOST]; if (cap_getnameinfo(capdns, (struct sockaddr *)from, from->sin6_len, hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0) strlcpy(hbuf, "invalid", sizeof(hbuf)); - if (as_path) - printf(" [AS%u]", as_lookup(asn, hbuf, AF_INET6)); + while (as_path) { + as = as_lookup(asn, hbuf, AF_INET6, &status); + if (status) { + as_shutdown(asn); + asn = as_setup(as_server); + if (asn == NULL) { + fprintf(stderr, "traceroute6: as_setup failed, AS# lookups" + " disabled\n"); + (void)fflush(stderr); + as_path = 0; + break; + } + else + continue; + } + printf(" [AS%u]", as); + break; + } if (nflag) printf(" %s", hbuf); elsehome | help
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