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Diffstat (limited to 'net-libs/adns/files/adns-1.4-cnamechain.patch')
| -rw-r--r-- | net-libs/adns/files/adns-1.4-cnamechain.patch | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/net-libs/adns/files/adns-1.4-cnamechain.patch b/net-libs/adns/files/adns-1.4-cnamechain.patch new file mode 100644 index 000000000000..4c87a1434660 --- /dev/null +++ b/net-libs/adns/files/adns-1.4-cnamechain.patch @@ -0,0 +1,132 @@ +[ADNS] Re: CNAME chains +Brad Spencer spencer at infointeractive.com +Mon, 28 Aug 2006 14:43:00 -0300 + +Previous message: CNAME chains +Next message: CNAME chains option +Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] +--pf9I7BMVVzbSWLtt +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline + +On Fri, Aug 25, 2006 at 11:36:04AM -0700, William Ahern wrote: +> On Fri, Aug 25, 2006 at 09:39:01AM +0100, peter burden wrote: +> > Hello, +> > Is there any way to make ADNS follow CNAME chains ? +> > +> > I have set the adns_qf_cname_loose query flag and it seems OK for a +> > single +> > CNAME - e.g. (output from 'dig') + +I posted a small patch back in 2003 that made changes to adns so that +it would follow CNAME chains. See + +http://www.chiark.greenend.org.uk/pipermail/adns-discuss/2003/001072.html + +The patch included in that post is against an old adns version, so I +have attached my latest version of the patch to this message. (I have +not tested that the attached patch applied cleanly to the current adns +source, but it may be slightly more in sync with the current version.) + +> CNAME chains are technically not allowed. Such chains are violations of the +> specifications. Also, I believe MX host lookups returning CNAMEs (i.e. MX +> yahoo.com -> A mail.yahoo.com -> CNAME foo) is also illegal. + +I have also been told that CNAME chains are illegal, but I can not +find any actual text that says that a resolver should fail when it +encounters them. In fact, RFC 1034 Section 3.6.2 says: + + Domain names in RRs which point at another name should always point at + the primary name and not the alias. This avoids extra indirections in + accessing information. For example, the address to name RR for the + above host should be: + + 52.0.0.10.IN-ADDR.ARPA IN PTR C.ISI.EDU + + rather than pointing at USC-ISIC.ARPA. + +The above implies that CNAME chains are illegal, IMO. But then, the +next sentence is: + + Of course, by the robustness principle, domain software should not + fail when presented with CNAME chains or loops; CNAME chains + should be followed and CNAME loops signalled as an error. + +This advice, coupled with the fact that CNAME chains exist in the +wild, triggered me to create the patch in the first place. My patch +doesn't detect loops, but instead simply won't follow chains longer +than a certain (hard-coded) size. + +Hope this helps! + +-- +------------------------------------------------------------------ +Brad Spencer - spencer@infointeractive.com - "It's quite nice..." +Systems Architect | InfoInterActive Corp. | A Canadian AOL Company + +--pf9I7BMVVzbSWLtt +Content-Type: text/plain; charset=us-ascii +Content-Disposition: attachment; filename="cname_chains.diff" + +Index: src/internal.h +=================================================================== +RCS file: /iia/cvsroot/3rdParty/gnu/adns/adns-1.0/src/internal.h,v +retrieving revision 1.3 +retrieving revision 1.4 +diff -u -p -r1.3 -r1.4 +--- src/internal.h 2 Oct 2003 17:01:46 -0000 1.3 ++++ src/internal.h 2 Oct 2003 17:14:29 -0000 1.4 +@@ -206,6 +206,9 @@ struct adns__query { + int cname_dglen, cname_begin; + /* If non-0, has been allocated using . */ + ++ int cname_alias_hops_left; ++ /* The number of cname alias hops we will allow */ ++ + vbuf search_vb; + int search_origlen, search_pos, search_doneabs; + /* Used by the searching algorithm. The query domain in textual form +Index: src/query.c +=================================================================== +RCS file: /iia/cvsroot/3rdParty/gnu/adns/adns-1.0/src/query.c,v +retrieving revision 1.3 +retrieving revision 1.4 +diff -u -p -r1.3 -r1.4 +--- src/query.c 2 Oct 2003 17:01:47 -0000 1.3 ++++ src/query.c 2 Oct 2003 17:14:29 -0000 1.4 +@@ -63,6 +63,8 @@ static adns_query query_alloc(adns_state + + qu->cname_dgram= 0; + qu->cname_dglen= qu->cname_begin= 0; ++ /* Allow CNAME chains up to some sane limit */ ++ qu->cname_alias_hops_left = 10; + + adns__vbuf_init(&qu->search_vb); + qu->search_origlen= qu->search_pos= qu->search_doneabs= 0; +Index: src/reply.c +=================================================================== +RCS file: /iia/cvsroot/3rdParty/gnu/adns/adns-1.0/src/reply.c,v +retrieving revision 1.3 +retrieving revision 1.4 +diff -u -p -r1.3 -r1.4 +--- src/reply.c 2 Oct 2003 17:01:47 -0000 1.3 ++++ src/reply.c 2 Oct 2003 17:14:30 -0000 1.4 +@@ -191,12 +191,13 @@ void adns__procdgram(adns_state ads, con + if (qu->flags & adns_qf_cname_forbid) { + adns__query_fail(qu,adns_s_prohibitedcname); + return; +- } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */ ++ } else if (qu->cname_dgram && --(qu->cname_alias_hops_left) <= 0) { /* Don't follow "too long" CNAME chains */ + adns__debug(ads,serv,qu,"allegedly canonical name %s" +- " is actually alias for %s", qu->answer->cname, ++ " is actually alias for %s and aliases too deep", ++ qu->answer->cname, + adns__diag_domain(ads,serv,qu, &qu->vb, + dgram,dglen,rdstart)); +- adns__query_fail(qu,adns_s_prohibitedcname); ++ adns__query_fail(qu,adns_s_norecurse); + return; + } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */ + adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR", + +--pf9I7BMVVzbSWLtt-- |