Warn early when parsing a too large DNS record

Signed-off-by: Remi Gacogne <remi.gacogne@powerdns.com>

diff --git a/pdns/dnsparser.cc b/pdns/dnsparser.cc
index 6b66788380505c734ce972f12e044d9231cec356..d22bbbf79cfaf72bad6e39ec05a6aba87f321998 100644 (file)
--- a/pdns/dnsparser.cc
+++ b/pdns/dnsparser.cc
@@ -372,6 +372,9 @@ void PacketReader::getDnsrecordheader(struct dnsrecordheader &ah)
 
   d_startrecordpos = d_pos; // needed for getBlob later on
   d_recordlen = ah.d_clen;
+  if (d_pos > d_content.size() || (d_content.size() - d_pos) < (d_recordlen)) {
+    throw std::out_of_range("DNS record length (" + std::to_string(d_recordlen) + " starting at " + std::to_string(d_pos) + ") goes beyond the packet's content (" + std::to_string(d_content.size()) + ")");
+  }
 }