From patchwork Wed Mar 15 12:43:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 739165 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3vjrrf1dcDz9ryj for ; Wed, 15 Mar 2017 23:44:02 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b="dAyiKOMV"; dkim-atps=neutral DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:references:from:message-id:date :mime-version:in-reply-to:content-type; q=dns; s=default; b=OokB 5TRshMHWyhi82GDnkwvKGz9S9888875UU7Y5DNTMD/A75eVVwh4ngr0jW4I/29oB IZlhpvF7QRKPs3/8CWuQTqj7EQf15PER408zgKarUOAoRtQg5NzoEcYwNwPC8+Ht nUMT+v26LzGcrW/NeP0SToYOh7Cexr1APVNi8mI= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:references:from:message-id:date :mime-version:in-reply-to:content-type; s=default; bh=P5QoNCSRUG MguHu9lmQLeDqXCKE=; b=dAyiKOMVx5y+358TIHvzch5Wm1dTCrw1qlX49BQJ9+ /4HnlaMSh2scJgrbmgILvaeE8rjQA3MGYU6ct86AGKCVmvv+93zK9OaRPEkarhuX 3wsm3agY6WlzaOBWYsmdBiTG3YjMIMU0csQ4KCi3hbhK30bNflo4xkMynlECqdIF c= Received: (qmail 62013 invoked by alias); 15 Mar 2017 12:43:53 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 62000 invoked by uid 89); 15 Mar 2017 12:43:52 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RP_MATCHES_RCVD, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=1718, 708, AAAA X-HELO: mx1.redhat.com DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 5857B8124A Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=fweimer@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 5857B8124A Subject: Re: [PATCH] support_format_dns_packet: Fix CNAME and multiple RR handling To: libc-alpha@sourceware.org References: <20170313163108.A062040196D5E@oldenburg.str.redhat.com> From: Florian Weimer Message-ID: <7dd1fd2f-46c3-9c41-a104-3cf0ef774af7@redhat.com> Date: Wed, 15 Mar 2017 13:43:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170313163108.A062040196D5E@oldenburg.str.redhat.com> Here is what I committed. Thanks, Florian support_format_dns_packet: Fix CNAME and multiple RR handling Before this change, the loop iterating over RRs in the answer section stopped at the first CNAME record, never printing them. The CNAME and PTR record contents was extracted from the wrong buffer (whole packet instead RDATA). This desynced the parsing after the first CNAME or PTR record. Also fix the AAAA record parsing by checking their sizes. 2017-03-15 Florian Weimer * support/support_format_dns_packet.c (support_format_dns_packet): Handle CNAME records in the response. Extract RDATA names from rdata, not the whole packet. Check AAAA record length. * support/tst-support_format_dns_packet.c: New file. * support/Makefile (tests): Add tst-support_format_dns_packet. (tst-support_format_dns_packet): Link against libresolv. diff --git a/support/Makefile b/support/Makefile index 2ace559..db7bb13 100644 --- a/support/Makefile +++ b/support/Makefile @@ -111,6 +111,7 @@ endif tests = \ README-testing \ tst-support-namespace \ + tst-support_format_dns_packet \ tst-support_record_failure \ ifeq ($(run-built-tests),yes) @@ -125,4 +126,6 @@ $(objpfx)tst-support_record_failure-2.out: tst-support_record_failure-2.sh \ $(evaluate-test) endif +$(objpfx)tst-support_format_dns_packet: $(common-objpfx)resolv/libresolv.so + include ../Rules diff --git a/support/support_format_dns_packet.c b/support/support_format_dns_packet.c index 21fe7e5..2992c57 100644 --- a/support/support_format_dns_packet.c +++ b/support/support_format_dns_packet.c @@ -174,7 +174,7 @@ support_format_dns_packet (const unsigned char *buffer, size_t length) goto out; } /* Skip non-matching record types. */ - if (rtype != qtype || rclass != qclass) + if ((rtype != qtype && rtype != T_CNAME) || rclass != qclass) continue; switch (rtype) { @@ -186,22 +186,29 @@ support_format_dns_packet (const unsigned char *buffer, size_t length) rdata.data[2], rdata.data[3]); else - fprintf (mem.out, "error: A record of size %d: %s\n", rdlen, rname.name); + fprintf (mem.out, "error: A record of size %d: %s\n", + rdlen, rname.name); break; case T_AAAA: { - char buf[100]; - if (inet_ntop (AF_INET6, rdata.data, buf, sizeof (buf)) == NULL) - fprintf (mem.out, "error: AAAA record decoding failed: %m\n"); + if (rdlen == 16) + { + char buf[100]; + if (inet_ntop (AF_INET6, rdata.data, buf, sizeof (buf)) == NULL) + fprintf (mem.out, "error: AAAA record decoding failed: %m\n"); + else + fprintf (mem.out, "address: %s\n", buf); + } else - fprintf (mem.out, "address: %s\n", buf); + fprintf (mem.out, "error: AAAA record of size %d: %s\n", + rdlen, rname.name); } break; case T_CNAME: case T_PTR: { struct dname name; - if (extract_name (full, &in, &name)) + if (extract_name (full, &rdata, &name)) fprintf (mem.out, "name: %s\n", name.name); else fprintf (mem.out, "error: malformed CNAME/PTR record\n"); diff --git a/support/tst-support_format_dns_packet.c b/support/tst-support_format_dns_packet.c new file mode 100644 index 0000000..ecd7abf --- /dev/null +++ b/support/tst-support_format_dns_packet.c @@ -0,0 +1,97 @@ +/* Tests for the support_format_dns_packet function. + Copyright (C) 2016-2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include +#include + +static void +check_packet (const void *buffer, size_t length, + const char *name, const char *expected) +{ + char *actual = support_format_dns_packet (buffer, length); + if (strcmp (actual, expected) != 0) + { + support_record_failure (); + printf ("error: formatted packet does not match: %s\n", name); + support_run_diff ("expected", expected, + "actual", actual); + } + free (actual); +} + +static void +test_aaaa_length (void) +{ + static const char packet[] = + /* Header: Response with two records. */ + "\x12\x34\x80\x00\x00\x01\x00\x02\x00\x00\x00\x00" + /* Question section. www.example/IN/AAAA. */ + "\x03www\x07""example\x00\x00\x1c\x00\x01" + /* Answer section. www.example AAAA [corrupted]. */ + "\xc0\x0c" + "\x00\x1c\x00\x01\x00\x00\x00\x00\x00\x10" + "\x20\x01\x0d\xb8\x05\x06\x07\x08" + "\x11\x12\x13\x14\x15\x16\x17\x18" + /* www.example AAAA [corrupted]. */ + "\xc0\x0c" + "\x00\x1c\x00\x01\x00\x00\x00\x00\x00\x11" + "\x01\x02\x03\x04\x05\x06\x07\x08" + "\x11\x12\x13\x14\x15\x16\x17\x18" "\xff"; + check_packet (packet, sizeof (packet) - 1, __func__, + "name: www.example\n" + "address: 2001:db8:506:708:1112:1314:1516:1718\n" + "error: AAAA record of size 17: www.example\n"); +} + +static void +test_multiple_cnames (void) +{ + static const char packet[] = + /* Header: Response with three records. */ + "\x12\x34\x80\x00\x00\x01\x00\x03\x00\x00\x00\x00" + /* Question section. www.example/IN/A. */ + "\x03www\x07""example\x00\x00\x01\x00\x01" + /* Answer section. www.example CNAME www1.example. */ + "\xc0\x0c" + "\x00\x05\x00\x01\x00\x00\x00\x00\x00\x07" + "\x04www1\xc0\x10" + /* www1 CNAME www2. */ + "\x04www1\xc0\x10" + "\x00\x05\x00\x01\x00\x00\x00\x00\x00\x07" + "\x04www2\xc0\x10" + /* www2 A 192.0.2.1. */ + "\x04www2\xc0\x10" + "\x00\x01\x00\x01\x00\x00\x00\x00\x00\x04" + "\xc0\x00\x02\x01"; + check_packet (packet, sizeof (packet) - 1, __func__, + "name: www.example\n" + "name: www1.example\n" + "name: www2.example\n" + "address: 192.0.2.1\n"); +} + +static int +do_test (void) +{ + test_aaaa_length (); + test_multiple_cnames (); + return 0; +} + +#include