From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Tue, 1 Sep 2020 08:14:40 +0000 (+0200)
Subject: dnsdist: Handle empty DNSNames in grepq()
X-Git-Tag: rec-4.5.0-alpha0~26^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fpull%2F9431%2Fhead;p=thirdparty%2Fpdns.git

dnsdist: Handle empty DNSNames in grepq()

We should not get an empty DNSName into the ring buffer, but let's
handle it gracefully if it does happen so we can investigate, instead
of getting:

Caught exception: empty dnsnames aren't part of anything
---

diff --git a/pdns/dnsdist-lua-inspection.cc b/pdns/dnsdist-lua-inspection.cc
index d01a007b11..180e6555a7 100644
--- a/pdns/dnsdist-lua-inspection.cc
+++ b/pdns/dnsdist-lua-inspection.cc
@@ -445,11 +445,18 @@ void setupLuaInspection()
       if(msec==-1) {
         for(const auto& c : qr) {
           bool nmmatch=true, dnmatch=true;
-          if(nm)
+          if (nm) {
             nmmatch = nm->match(c.requestor);
-          if(dn)
-            dnmatch = c.name.isPartOf(*dn);
-          if(nmmatch && dnmatch) {
+          }
+          if (dn) {
+            if (c.name.empty()) {
+              dnmatch = false;
+            }
+            else {
+              dnmatch = c.name.isPartOf(*dn);
+            }
+          }
+          if (nmmatch && dnmatch) {
             QType qt(c.qtype);
             std::string extra;
             if (c.dh.opcode != 0) {
@@ -468,26 +475,40 @@ void setupLuaInspection()
       string extra;
       for(const auto& c : rr) {
         bool nmmatch=true, dnmatch=true, msecmatch=true;
-        if(nm)
+        if (nm) {
           nmmatch = nm->match(c.requestor);
-        if(dn)
-          dnmatch = c.name.isPartOf(*dn);
-        if(msec != -1)
+        }
+        if (dn) {
+          if (c.name.empty()) {
+            dnmatch = false;
+          }
+          else {
+            dnmatch = c.name.isPartOf(*dn);
+          }
+        }
+        if (msec != -1) {
           msecmatch=(c.usec/1000 > (unsigned int)msec);
+        }
 
-        if(nmmatch && dnmatch && msecmatch) {
+        if (nmmatch && dnmatch && msecmatch) {
           QType qt(c.qtype);
-	  if(!c.dh.rcode)
+	  if (!c.dh.rcode) {
 	    extra=". " +std::to_string(htons(c.dh.ancount))+ " answers";
-	  else
+          }
+	  else {
 	    extra.clear();
-          if(c.usec != std::numeric_limits<decltype(c.usec)>::max())
+          }
+
+          if (c.usec != std::numeric_limits<decltype(c.usec)>::max()) {
             out.insert(make_pair(c.when, (fmt % DiffTime(now, c.when) % c.requestor.toStringWithPort() % c.ds.toStringWithPort() % htons(c.dh.id) % c.name.toString()  % qt.getName()  % (c.usec/1000.0) % (c.dh.tc ? "TC" : "") % (c.dh.rd? "RD" : "") % (c.dh.aa? "AA" : "") % (RCode::to_s(c.dh.rcode) + extra)).str()  )) ;
-          else
+          }
+          else {
             out.insert(make_pair(c.when, (fmt % DiffTime(now, c.when) % c.requestor.toStringWithPort() % c.ds.toStringWithPort() % htons(c.dh.id) % c.name.toString()  % qt.getName()  % "T.O" % (c.dh.tc ? "TC" : "") % (c.dh.rd? "RD" : "") % (c.dh.aa? "AA" : "") % (RCode::to_s(c.dh.rcode) + extra)).str()  )) ;
+          }
 
-          if(limit && *limit==++num)
+          if (limit && *limit == ++num) {
             break;
+          }
         }
       }