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 d01a007b11033247ed72836144c178f36141ebdc..180e6555a757a4574ad73675e9759f7e294a71c1 100644 (file)
--- 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;
+          }
         }
       }