Smarter hashing of header and query

PowerDNS · Jun 1, 2022 · b2c3da4 · b2c3da4
1 parent 1b5aa11
commit b2c3da4
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Showing 3 changed files with 9 additions and 17 deletions.
diff --git a/pdns/Makefile.am b/pdns/Makefile.am
@@ -196,10 +196,10 @@ pdns_server_SOURCES = \
 	backends/gsql/ssql.hh \
 	base32.cc base32.hh \
 	base64.cc base64.hh \
-	burtle.hh \
 	bind-dnssec.schema.sqlite3.sql.h \
 	bindlexer.l \
 	bindparser.cc \
+	burtle.hh \
 	cachecleaner.hh \
 	circular_buffer.hh \
 	comment.hh \

diff --git a/pdns/packetcache.hh b/pdns/packetcache.hh
@@ -105,27 +105,19 @@ public:
 
   static uint32_t hashHeaderAndQName(const std::string& packet, size_t& pos)
   {
-    uint32_t currentHash = 0;
     const size_t packetSize = packet.size();
     assert(packetSize >= sizeof(dnsheader));
-    currentHash = burtle(reinterpret_cast<const unsigned char*>(&packet.at(2)), sizeof(dnsheader) - 2, currentHash); // rest of dnsheader, skip id
-    pos = sizeof(dnsheader);
+    uint32_t currentHash = burtle(reinterpret_cast<const unsigned char*>(&packet.at(2)), sizeof(dnsheader) - 2, 0); // rest of dnsheader, skip id
 
-    for (; pos < packetSize; ) {
+    for (pos = sizeof(dnsheader); pos < packetSize; ) {
       const unsigned char labelLen = static_cast<unsigned char>(packet.at(pos));
-      currentHash = burtle(&labelLen, 1, currentHash);
       ++pos;
       if (labelLen == 0) {
         break;
       }
-
-      for (size_t idx = 0; idx < labelLen && pos < packetSize; ++idx, ++pos) {
-        const unsigned char l = dns_tolower(packet.at(pos));
-        currentHash = burtle(&l, 1, currentHash);
-      }
+      pos = std::min(pos + labelLen, packetSize);
     }
-
-    return currentHash;
+    return burtleCI(reinterpret_cast<const unsigned char*>(&packet.at(sizeof(dnsheader))), pos - sizeof(dnsheader), currentHash);
   }
 
   /* hash the packet from the beginning, including the qname. This skips:

diff --git a/pdns/test-packetcache_hh.cc b/pdns/test-packetcache_hh.cc
@@ -53,7 +53,7 @@ BOOST_AUTO_TEST_CASE(test_PacketCacheAuthCollision) {
     pw1.getHeader()->rd = true;
     pw1.getHeader()->qr = false;
     pw1.getHeader()->id = 0x42;
-    opt.source = Netmask("10.0.152.74/32");
+    opt.source = Netmask("10.0.59.220/32");
     ednsOptions.clear();
     ednsOptions.emplace_back(EDNSOptionCode::ECS, makeEDNSSubnetOptsString(opt));
     pw1.addOpt(512, 0, 0, ednsOptions);
@@ -67,7 +67,7 @@ BOOST_AUTO_TEST_CASE(test_PacketCacheAuthCollision) {
     pw2.getHeader()->rd = true;
     pw2.getHeader()->qr = false;
     pw2.getHeader()->id = 0x84;
-    opt.source = Netmask("10.2.70.250/32");
+    opt.source = Netmask("10.0.167.48/32");
     ednsOptions.clear();
     ednsOptions.emplace_back(EDNSOptionCode::ECS, makeEDNSSubnetOptsString(opt));
     pw2.addOpt(512, 0, 0, ednsOptions);
@@ -125,7 +125,7 @@ BOOST_AUTO_TEST_CASE(test_PacketCacheAuthCollision) {
     pw1.getHeader()->rd = true;
     pw1.getHeader()->qr = false;
     pw1.getHeader()->id = 0x42;
-    opt.source = Netmask("10.0.34.159/32");
+    opt.source = Netmask("10.0.41.6/32");
     ednsOptions.clear();
     ednsOptions.emplace_back(EDNSOptionCode::ECS, makeEDNSSubnetOptsString(opt));
     pw1.addOpt(512, 0, EDNSOpts::DNSSECOK, ednsOptions);
@@ -139,7 +139,7 @@ BOOST_AUTO_TEST_CASE(test_PacketCacheAuthCollision) {
     pw2.getHeader()->rd = true;
     pw2.getHeader()->qr = false;
     pw2.getHeader()->id = 0x84;
-    opt.source = Netmask("10.0.179.58/32");
+    opt.source = Netmask("10.0.119.79/32");
     ednsOptions.clear();
     ednsOptions.emplace_back(EDNSOptionCode::ECS, makeEDNSSubnetOptsString(opt));
     /* no EDNSOpts::DNSSECOK !! */