diff options
| -rw-r--r-- | src/network/res_msend.c | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/src/network/res_msend.c b/src/network/res_msend.c index 5192b4d8..35f106dd 100644 --- a/src/network/res_msend.c +++ b/src/network/res_msend.c @@ -34,7 +34,7 @@ int __res_msend(int nqueries, const unsigned char *const *queries, FILE *f, _f; unsigned char _buf[256]; char line[64], *s, *z; - int timeout = 5000, attempts = 2, retry_interval; + int timeout = 5000, attempts = 2, retry_interval, servfail_retry; union { struct sockaddr_in sin; struct sockaddr_in6 sin6; @@ -152,6 +152,7 @@ int __res_msend(int nqueries, const unsigned char *const *queries, qlens[i], MSG_NOSIGNAL, (void *)&ns[j], sl); t1 = t2; + servfail_retry = 2 * nqueries; } /* Wait for a response, or until time to retry */ @@ -160,12 +161,12 @@ int __res_msend(int nqueries, const unsigned char *const *queries, while ((rlen = recvfrom(fd, answers[next], asize, 0, (void *)&sa, (socklen_t[1]){sl})) >= 0) { - /* Ignore non-identifiable packets (no query id) */ - if (rlen < 2) continue; + /* Ignore non-identifiable packets */ + if (rlen < 4) continue; /* Ignore replies from addresses we didn't send to */ - for (i=0; i<nns && memcmp(ns+i, &sa, sl); i++); - if (i==nns) continue; + for (j=0; j<nns && memcmp(ns+j, &sa, sl); j++); + if (j==nns) continue; /* Find which query this answer goes with, if any */ for (i=next; i<nqueries && ( @@ -174,6 +175,22 @@ int __res_msend(int nqueries, const unsigned char *const *queries, if (i==nqueries) continue; if (alens[i]) continue; + /* Only accept positive or negative responses; + * retry immediately on server failure, and ignore + * all other codes such as refusal. */ + switch (answers[next][3] & 15) { + case 0: + case 3: + break; + case 2: + if (servfail_retry && servfail_retry--) + sendto(fd, queries[i], + qlens[i], MSG_NOSIGNAL, + (void *)&ns[j], sl); + default: + continue; + } + /* Store answer in the right slot, or update next * available temp slot if it's already in place. */ alens[i] = rlen; |