From a5c9534d02f9ccd84787bcdd253c5b817f92d797 Mon Sep 17 00:00:00 2001 From: Remi Gacogne Date: Thu, 22 Jun 2017 10:25:47 +0200 Subject: [PATCH] rec: Treat requestor's payload size lower than 512 as equal to 512 (cherry picked from commit 320157487ec1cd0a9c4bcfd5309d9d651c26eb72) --- pdns/pdns_recursor.cc | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc index 67c9aedd4..0b7bbd44d 100644 --- a/pdns/pdns_recursor.cc +++ b/pdns/pdns_recursor.cc @@ -694,12 +694,16 @@ void startDoResolve(void *p) if (t_queryring) t_queryring->push_back(make_pair(dc->d_mdp.d_qname, dc->d_mdp.d_qtype)); - uint32_t maxanswersize= dc->d_tcp ? 65535 : min((uint16_t) 512, g_udpTruncationThreshold); + uint16_t maxanswersize = dc->d_tcp ? 65535 : min(static_cast(512), g_udpTruncationThreshold); EDNSOpts edo; bool haveEDNS=false; if(getEDNSOpts(dc->d_mdp, &edo)) { - if(!dc->d_tcp) - maxanswersize = min(edo.d_packetsize, g_udpTruncationThreshold); + if(!dc->d_tcp) { + /* rfc6891 6.2.3: + "Values lower than 512 MUST be treated as equal to 512." + */ + maxanswersize = min(static_cast(edo.d_packetsize >= 512 ? edo.d_packetsize : 512), g_udpTruncationThreshold); + } dc->d_ednsOpts = edo.d_options; haveEDNS=true; @@ -1086,7 +1090,7 @@ void startDoResolve(void *p) if(i->d_type != QType::OPT) // their TTL ain't real minTTL = min(minTTL, i->d_ttl); i->d_content->toPacket(pw); - if(pw.size() > maxanswersize) { + if(pw.size() > static_cast(maxanswersize)) { pw.rollback(); if(i->d_place==DNSResourceRecord::ANSWER) // only truncate if we actually omitted parts of the answer { -- 2.50.0