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Consolidate DNS query matching to one place

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This commit is contained in:
dmiller 2026-08-18 16:06:51 +00:00
parent 4fa4238789
commit 07785203c9
1 changed files with 27 additions and 21 deletions
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48
libnetutil/massdns.cc
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@ -482,7 +482,7 @@ private:
int deal_with_timedout_reads(bool adjust_timing);
void process_request(int action, info &reqinfo);
bool process_result(const std::string &name, const Record *rr,
info &reqinfo, bool already_matched);
info &reqinfo);
bool system_resolve(DNS::Request &reqt);
void output_summary(const Stats &stat);
@ -1161,7 +1161,7 @@ bool iequals(const std::string &a, const std::string &b)
// After processing a DNS response, we search through the IPs we're
// looking for and update their results as necessary.
bool DNS::ResolverImpl::process_result(const std::string &name, const DNS::Record *rr,
info &reqinfo, bool already_matched)
info &reqinfo)
{
DNS::Request *reqt = reqinfo.tpreq->targ;
std::vector<struct sockaddr_storage> *ssv;
@ -1180,9 +1180,6 @@ bool DNS::ResolverImpl::process_result(const std::string &name, const DNS::Recor
case DNS::A:
case DNS::AAAA:
case DNS::ANY:
if (!already_matched && !iequals(name, reqt->name)) {
return false;
}
a_rec = static_cast<const DNS::A_Record *>(rr);
ssv->push_back(a_rec->value);
log_func(TRACE_DEBUG_LEVEL, "mass_dns: OK MATCHED <%s> to <%s>\n",
@ -1191,12 +1188,6 @@ bool DNS::ResolverImpl::process_result(const std::string &name, const DNS::Recor
break;
case DNS::PTR:
ss = &reqt->ssv.front();
if (!already_matched) {
if (!DNS::Factory::ptrToIp(name, ip) ||
!sockaddr_storage_equal(&ip, ss)) {
return false;
}
}
reqt->name = static_cast<const DNS::PTR_Record *>(rr)->value;
host_cache.add(*ss, reqt->name);
log_func(TRACE_DEBUG_LEVEL, "mass_dns: OK MATCHED <%s> to <%s>\n",
@ -1261,6 +1252,25 @@ void DNS::ResolverImpl::handle_read(nsock_pool nsp, nsock_event evt, dns_server
assert(p.id == reqinfo.tpreq->id);
DNS::Request *reqt = reqinfo.tpreq->targ;
assert(reqt != NULL);
// Response must contain a matching query. p.queries.empty() was already checked.
const DNS::Query &q = p.queries.front();
// Query must match in class and type
if (q.record_class != DNS::CLASS_IN
|| q.record_type != wire_type(reqt->type)) {
return;
}
// Query must match requested name
std::string tmp;
const std::string *qname = &reqt->name;
if (reqt->type == DNS::PTR) {
assert(reqt->ssv.size() > 0);
// TODO: we already did this to build the request; can we keep it around?
DNS::Factory::ipToPtr(reqt->ssv.front(), tmp);
qname = &tmp;
}
if (!iequals(q.name, *qname)) {
return;
}
bool processing_successful = false;
if (DNS_HAS_ERR(f, DNS::ERR_NAME) || p.answers.empty())
@ -1303,28 +1313,24 @@ void DNS::ResolverImpl::handle_read(nsock_pool nsp, nsock_event evt, dns_server
sockaddr_storage ip;
ip.ss_family = AF_UNSPEC;
std::string alias;
for(std::list<DNS::Answer>::const_iterator it = p.answers.begin();
it != p.answers.end(); ++it )
{
const DNS::Answer &a = *it;
if(a.record_class == DNS::CLASS_IN)
if(a.record_class == DNS::CLASS_IN
&& (iequals(a.name, *qname) || iequals(a.name, q.name)))
{
if (wire_type(reqt->type) == a.record_type) {
processing_successful = process_result(a.name, a.record, reqinfo, iequals(a.name,alias));
processing_successful = process_result(a.name, a.record, tpreq);
if (!processing_successful) {
log_func(1, "mass_dns: Mismatched record for request %s\n", reqt->repr());
}
}
else if (a.record_type == DNS::CNAME) {
const DNS::CNAME_Record *cname = static_cast<const DNS::CNAME_Record *>(a.record);
if((reqt->type == DNS::PTR && DNS::Factory::ptrToIp(a.name, ip))
|| iequals(a.name, reqt->name) || (!alias.empty() && iequals(a.name, alias)))
{
alias = cname->value;
log_func(TRACE_DEBUG_LEVEL, "mass_dns: CNAME found for <%s> to <%s>\n", a.name.c_str(), alias.c_str());
}
qname = &cname->value;
log_func(TRACE_DEBUG_LEVEL, "mass_dns: CNAME found for <%s> to <%s>\n", a.name.c_str(), qname->c_str());
}
}
}
@ -1334,7 +1340,7 @@ void DNS::ResolverImpl::handle_read(nsock_pool nsp, nsock_event evt, dns_server
// TODO: TCP fallback, or only use system resolver if user didn't specify --dns-servers
process_request(ACTION_SYSTEM_RESOLVE, reqinfo);
}
else if (!alias.empty()) {
else if (!iequals(q.name, *qname)) {
log_func(TRACE_DEBUG_LEVEL, "mass_dns: CNAME for <%s> not processed.\n", reqt->repr());
// TODO: Send a PTR request for alias instead. Meanwhile, we'll just fall
// back to using system resolver. Alternative: report the canonical name