318 lines
9.3 KiB
Diff
318 lines
9.3 KiB
Diff
From 7602be276a73a6eb5431c5acd9718e68a55e8b61 Mon Sep 17 00:00:00 2001
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From: Mark Andrews <marka@isc.org>
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Date: Mon, 29 Feb 2016 07:16:48 +1100
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Subject: [PATCH] Part 2 of: 4319. [security] Fix resolver assertion
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failure due to improper DNAME handling when parsing
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fetch reply messages. (CVE-2016-1286) [RT #41753]
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CVE: CVE-2016-1286
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Upstream-Status: Backport
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(cherry picked from commit 2de89ee9de8c8da9dc153a754b02dcdbb7fe2374)
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Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
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---
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lib/dns/resolver.c | 192 ++++++++++++++++++++++++++---------------------------
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1 file changed, 93 insertions(+), 99 deletions(-)
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diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
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index 70aba87..41e9df4 100644
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--- a/lib/dns/resolver.c
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+++ b/lib/dns/resolver.c
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@@ -6074,14 +6074,11 @@ cname_target(dns_rdataset_t *rdataset, dns_name_t *tname) {
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}
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static inline isc_result_t
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-dname_target(fetchctx_t *fctx, dns_rdataset_t *rdataset, dns_name_t *qname,
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- dns_name_t *oname, dns_fixedname_t *fixeddname)
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+dname_target(dns_rdataset_t *rdataset, dns_name_t *qname,
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+ unsigned int nlabels, dns_fixedname_t *fixeddname)
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{
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isc_result_t result;
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dns_rdata_t rdata = DNS_RDATA_INIT;
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- unsigned int nlabels;
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- int order;
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- dns_namereln_t namereln;
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dns_rdata_dname_t dname;
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dns_fixedname_t prefix;
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@@ -6096,21 +6093,6 @@ dname_target(fetchctx_t *fctx, dns_rdataset_t *rdataset, dns_name_t *qname,
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if (result != ISC_R_SUCCESS)
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return (result);
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- /*
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- * Get the prefix of qname.
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- */
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- namereln = dns_name_fullcompare(qname, oname, &order, &nlabels);
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- if (namereln != dns_namereln_subdomain) {
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- char qbuf[DNS_NAME_FORMATSIZE];
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- char obuf[DNS_NAME_FORMATSIZE];
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-
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- dns_rdata_freestruct(&dname);
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- dns_name_format(qname, qbuf, sizeof(qbuf));
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- dns_name_format(oname, obuf, sizeof(obuf));
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- log_formerr(fctx, "unrelated DNAME in answer: "
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- "%s is not in %s", qbuf, obuf);
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- return (DNS_R_FORMERR);
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- }
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dns_fixedname_init(&prefix);
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dns_name_split(qname, nlabels, dns_fixedname_name(&prefix), NULL);
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dns_fixedname_init(fixeddname);
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@@ -6736,13 +6718,13 @@ static isc_result_t
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answer_response(fetchctx_t *fctx) {
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isc_result_t result;
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dns_message_t *message;
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- dns_name_t *name, *qname, tname, *ns_name;
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+ dns_name_t *name, *dname, *qname, tname, *ns_name;
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dns_rdataset_t *rdataset, *ns_rdataset;
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isc_boolean_t done, external, chaining, aa, found, want_chaining;
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isc_boolean_t have_answer, found_cname, found_type, wanted_chaining;
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unsigned int aflag;
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dns_rdatatype_t type;
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- dns_fixedname_t dname, fqname;
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+ dns_fixedname_t fdname, fqname;
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dns_view_t *view;
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FCTXTRACE("answer_response");
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@@ -6770,10 +6752,15 @@ answer_response(fetchctx_t *fctx) {
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view = fctx->res->view;
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result = dns_message_firstname(message, DNS_SECTION_ANSWER);
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while (!done && result == ISC_R_SUCCESS) {
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+ dns_namereln_t namereln;
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+ int order;
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+ unsigned int nlabels;
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+
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name = NULL;
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dns_message_currentname(message, DNS_SECTION_ANSWER, &name);
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external = ISC_TF(!dns_name_issubdomain(name, &fctx->domain));
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- if (dns_name_equal(name, qname)) {
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+ namereln = dns_name_fullcompare(qname, name, &order, &nlabels);
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+ if (namereln == dns_namereln_equal) {
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wanted_chaining = ISC_FALSE;
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for (rdataset = ISC_LIST_HEAD(name->list);
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rdataset != NULL;
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@@ -6898,10 +6885,11 @@ answer_response(fetchctx_t *fctx) {
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*/
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INSIST(!external);
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if (aflag ==
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- DNS_RDATASETATTR_ANSWER)
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+ DNS_RDATASETATTR_ANSWER) {
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have_answer = ISC_TRUE;
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- name->attributes |=
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- DNS_NAMEATTR_ANSWER;
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+ name->attributes |=
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+ DNS_NAMEATTR_ANSWER;
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+ }
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rdataset->attributes |= aflag;
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if (aa)
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rdataset->trust =
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@@ -6956,6 +6944,8 @@ answer_response(fetchctx_t *fctx) {
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if (wanted_chaining)
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chaining = ISC_TRUE;
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} else {
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+ dns_rdataset_t *dnameset = NULL;
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+
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/*
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* Look for a DNAME (or its SIG). Anything else is
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* ignored.
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@@ -6963,10 +6953,8 @@ answer_response(fetchctx_t *fctx) {
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wanted_chaining = ISC_FALSE;
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for (rdataset = ISC_LIST_HEAD(name->list);
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rdataset != NULL;
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- rdataset = ISC_LIST_NEXT(rdataset, link)) {
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- isc_boolean_t found_dname = ISC_FALSE;
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- dns_name_t *dname_name;
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-
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+ rdataset = ISC_LIST_NEXT(rdataset, link))
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+ {
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/*
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* Only pass DNAME or RRSIG(DNAME).
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*/
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@@ -6980,20 +6968,41 @@ answer_response(fetchctx_t *fctx) {
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* its signature should not be external.
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*/
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if (!chaining && external) {
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- log_formerr(fctx, "external DNAME");
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+ char qbuf[DNS_NAME_FORMATSIZE];
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+ char obuf[DNS_NAME_FORMATSIZE];
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+
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+ dns_name_format(name, qbuf,
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+ sizeof(qbuf));
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+ dns_name_format(&fctx->domain, obuf,
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+ sizeof(obuf));
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+ log_formerr(fctx, "external DNAME or "
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+ "RRSIG covering DNAME "
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+ "in answer: %s is "
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+ "not in %s", qbuf, obuf);
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+ return (DNS_R_FORMERR);
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+ }
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+
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+ if (namereln != dns_namereln_subdomain) {
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+ char qbuf[DNS_NAME_FORMATSIZE];
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+ char obuf[DNS_NAME_FORMATSIZE];
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+
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+ dns_name_format(qname, qbuf,
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+ sizeof(qbuf));
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+ dns_name_format(name, obuf,
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+ sizeof(obuf));
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+ log_formerr(fctx, "unrelated DNAME "
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+ "in answer: %s is "
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+ "not in %s", qbuf, obuf);
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return (DNS_R_FORMERR);
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}
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- found = ISC_FALSE;
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aflag = 0;
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if (rdataset->type == dns_rdatatype_dname) {
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- found = ISC_TRUE;
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want_chaining = ISC_TRUE;
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POST(want_chaining);
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aflag = DNS_RDATASETATTR_ANSWER;
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- result = dname_target(fctx, rdataset,
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- qname, name,
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- &dname);
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+ result = dname_target(rdataset, qname,
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+ nlabels, &fdname);
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if (result == ISC_R_NOSPACE) {
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/*
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* We can't construct the
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@@ -7005,14 +7014,12 @@ answer_response(fetchctx_t *fctx) {
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} else if (result != ISC_R_SUCCESS)
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return (result);
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else
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- found_dname = ISC_TRUE;
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+ dnameset = rdataset;
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- dname_name = dns_fixedname_name(&dname);
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+ dname = dns_fixedname_name(&fdname);
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if (!is_answertarget_allowed(view,
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- qname,
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- rdataset->type,
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- dname_name,
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- &fctx->domain)) {
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+ qname, rdataset->type,
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+ dname, &fctx->domain)) {
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return (DNS_R_SERVFAIL);
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}
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} else {
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@@ -7020,73 +7027,60 @@ answer_response(fetchctx_t *fctx) {
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* We've found a signature that
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* covers the DNAME.
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*/
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- found = ISC_TRUE;
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aflag = DNS_RDATASETATTR_ANSWERSIG;
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}
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- if (found) {
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+ /*
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+ * We've found an answer to our
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+ * question.
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+ */
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+ name->attributes |= DNS_NAMEATTR_CACHE;
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+ rdataset->attributes |= DNS_RDATASETATTR_CACHE;
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+ rdataset->trust = dns_trust_answer;
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+ if (!chaining) {
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/*
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- * We've found an answer to our
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- * question.
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+ * This data is "the" answer to
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+ * our question only if we're
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+ * not chaining.
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*/
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- name->attributes |=
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- DNS_NAMEATTR_CACHE;
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- rdataset->attributes |=
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- DNS_RDATASETATTR_CACHE;
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- rdataset->trust = dns_trust_answer;
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- if (!chaining) {
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- /*
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- * This data is "the" answer
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- * to our question only if
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- * we're not chaining.
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- */
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- INSIST(!external);
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- if (aflag ==
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- DNS_RDATASETATTR_ANSWER)
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- have_answer = ISC_TRUE;
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+ INSIST(!external);
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+ if (aflag == DNS_RDATASETATTR_ANSWER) {
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+ have_answer = ISC_TRUE;
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name->attributes |=
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DNS_NAMEATTR_ANSWER;
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- rdataset->attributes |= aflag;
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- if (aa)
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- rdataset->trust =
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- dns_trust_authanswer;
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- } else if (external) {
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- rdataset->attributes |=
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- DNS_RDATASETATTR_EXTERNAL;
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- }
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-
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- /*
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- * DNAME chaining.
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- */
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- if (found_dname) {
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- /*
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- * Copy the dname into the
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- * qname fixed name.
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- *
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- * Although we check for
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- * failure of the copy
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- * operation, in practice it
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- * should never fail since
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- * we already know that the
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- * result fits in a fixedname.
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- */
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- dns_fixedname_init(&fqname);
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- result = dns_name_copy(
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- dns_fixedname_name(&dname),
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- dns_fixedname_name(&fqname),
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- NULL);
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- if (result != ISC_R_SUCCESS)
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- return (result);
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- wanted_chaining = ISC_TRUE;
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- name->attributes |=
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- DNS_NAMEATTR_CHAINING;
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- rdataset->attributes |=
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- DNS_RDATASETATTR_CHAINING;
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- qname = dns_fixedname_name(
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- &fqname);
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}
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+ rdataset->attributes |= aflag;
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+ if (aa)
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+ rdataset->trust =
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+ dns_trust_authanswer;
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+ } else if (external) {
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+ rdataset->attributes |=
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+ DNS_RDATASETATTR_EXTERNAL;
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}
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}
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+
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+ /*
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+ * DNAME chaining.
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+ */
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+ if (dnameset != NULL) {
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+ /*
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+ * Copy the dname into the qname fixed name.
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+ *
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+ * Although we check for failure of the copy
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+ * operation, in practice it should never fail
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+ * since we already know that the result fits
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+ * in a fixedname.
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+ */
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+ dns_fixedname_init(&fqname);
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+ qname = dns_fixedname_name(&fqname);
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+ result = dns_name_copy(dname, qname, NULL);
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+ if (result != ISC_R_SUCCESS)
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+ return (result);
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+ wanted_chaining = ISC_TRUE;
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+ name->attributes |= DNS_NAMEATTR_CHAINING;
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+ dnameset->attributes |=
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+ DNS_RDATASETATTR_CHAINING;
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+ }
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if (wanted_chaining)
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chaining = ISC_TRUE;
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}
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--
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1.9.1
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