From: Otto Moerbeek <otto.moerbeek@open-xchange.com>
Date: Mon, 9 May 2022 06:43:07 +0000 (+0200)
Subject: Add a comment wrt hashing the header
X-Git-Tag: auth-4.8.0-alpha0~57^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3c2c5503ca528fc750cd3d89a4f8ead265b2588d;p=thirdparty%2Fpdns.git

Add a comment wrt hashing the header
---

diff --git a/pdns/packetcache.hh b/pdns/packetcache.hh
index 08c3546fb1..2da156cb0b 100644
--- a/pdns/packetcache.hh
+++ b/pdns/packetcache.hh
@@ -107,6 +107,10 @@ public:
   {
     const size_t packetSize = packet.size();
     assert(packetSize >= sizeof(dnsheader));
+    // Quite some bits in the header are actually irrelevant for
+    // incoming queries.  If we ever change that and ignore them for
+    // hashing, don't forget to also adapt the `queryHeaderMatches`
+    // code, as it should be consistent with the hash function.
     uint32_t currentHash = burtle(reinterpret_cast<const unsigned char*>(&packet.at(2)), sizeof(dnsheader) - 2, 0); // rest of dnsheader, skip id
 
     for (pos = sizeof(dnsheader); pos < packetSize; ) {