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| author | Siddhesh Poyarekar <siddhesh@redhat.com> | 2012-03-30 20:58:14 +0530 |
|---|---|---|
| committer | Siddhesh Poyarekar <siddhesh@redhat.com> | 2012-03-30 21:30:01 +0530 |
| commit | 48c41d04ee06efc6ec97325ed6697c121b40865f (patch) | |
| tree | d954e0201566cb3844d831217fd8753573ff51da /resolv/nss_dns | |
| parent | 2f5a5ed02c346e5debc89b82a7c7e0eacc37a107 (diff) | |
| download | glibc-48c41d04ee06efc6ec97325ed6697c121b40865f.tar.gz glibc-48c41d04ee06efc6ec97325ed6697c121b40865f.tar.xz glibc-48c41d04ee06efc6ec97325ed6697c121b40865f.zip | |
Consider TTL of CNAME record and return minimum TTL in the chain
[BZ #13928] A DNS request consists of multiple resources combined into a single hostent, including multiple CNAME records that may have been assigned different TTL values. In such a case, nscd should take the least TTL among all of the resources as the timeout for the hostent before it is reloaded in its cache so that the hostent remains stale in the database for the least amount of time.
Diffstat (limited to 'resolv/nss_dns')
| -rw-r--r-- | resolv/nss_dns/dns-host.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c index 3b287b717a..ba83c440cc 100644 --- a/resolv/nss_dns/dns-host.c +++ b/resolv/nss_dns/dns-host.c @@ -1,4 +1,4 @@ -/* Copyright (C) 1996-2004, 2007-2009, 2010, 2012 Free Software Foundation, Inc. +/* Copyright (C) 1996-2004, 2007-2010, 2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996. @@ -744,6 +744,10 @@ getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype, if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) { + /* A CNAME could also have a TTL entry. */ + if (ttlp != NULL && ttl < *ttlp) + *ttlp = ttl; + if (ap >= &host_data->aliases[MAX_NR_ALIASES - 1]) continue; n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf); @@ -905,7 +909,10 @@ getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype, { register int nn; - if (ttlp != NULL) + /* We compose a single hostent out of the entire chain of + entries, so the TTL of the hostent is essentially the lowest + TTL in the chain. */ + if (ttlp != NULL && ttl < *ttlp) *ttlp = ttl; if (canonp != NULL) *canonp = bp; @@ -1081,6 +1088,11 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname, if (type == T_CNAME) { char tbuf[MAXDNAME]; + + /* A CNAME could also have a TTL entry. */ + if (ttlp != NULL && ttl < *ttlp) + *ttlp = ttl; + n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf); if (__builtin_expect (n < 0 || res_hnok (tbuf) == 0, 0)) { @@ -1161,7 +1173,10 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname, if (*firstp) { - if (ttlp != NULL) + /* We compose a single hostent out of the entire chain of + entries, so the TTL of the hostent is essentially the lowest + TTL in the chain. */ + if (ttlp != NULL && ttl < *ttlp) *ttlp = ttl; (*pat)->name = canon ?: h_name; |