Software Update: PowerDNS Authoritative Server 2.9.22

PowerDNS is a dns server with a database as backend, which makes it easy to manage a large number of dns entries. The developers decided in April 2006 to release the two parts that make up PowerDNS, a recursor and an authoritative name server. This allows new versions to be released faster, according to the developers. A while ago a new version of PowerDNS Authoritative Server was released. Version 2.9.22 brings a lot of changes and improvements, as can be read in the announcement and the list of changes:

PowerDNS Authoritative Server version 2.9.22 released!

This is a huge release, spanning almost 20 months of development. Besides fixing a lot of bugs, of note is the addition of the so called ‘Notification Proxy’, which allows PowerDNS to function as a master server behind a firewall, plus the huge performance improvement of the internal caches.

This work has been made possible by UPC Broadband and Directi, respectively.

Finally, the release candidates of this version have been tested & improved by Jorn Ekkelenkamp, ​​Ton van Rosmalen, Jeff Sipek, Tyler Hall, Christof Meerwald and Stefan Schmidt.

Fixed between rc1 and rc2, but not an issue in 2.9.21.

• pdns_control accounts again outputs proper cache statistics. Implemented in commit 1304.
• Negative query caching was reinstated, leading to 6 times fewer backend queries than rc1 on the Express.powerdns.com servers.
• Packet cache no longer needlessly parses outgoing packets before sending them.
• Fancy records work again. This work has been sponsored by ISP Services. Implemented in commit 1302 and commit 1299.

New features:

• pdns_control can now also work over TCP/IP. Sponsored by Directi. Commits 1246, 1251, 1254, 1255.
• Implemented a notification proxy, see Section 19.1. This work was sponsored by UPC Broadband. Implemented in commits 1075, 1077, 1082, 1083, 1085 and 1086.
• IXFR queries are now supported in the sense that we treat them as AXFR queries, silencing warnings in other nameservers. Suggested in ticket 131.
• The PIPE backend has been extended by David Apgar to allow the reporting of errors using the ‘FAIL’ command, plus support for responses with whitespace. Implemented in commit 1114.
• PowerDNS Authoritative server now parses incoming EDNS options, like maximum allowed packet size. Implemented in commit 1123 and commit 1281.
• Added support for DHCID, IPSECKEY and KX records, thanks Norbert Sendetzky for the hint. Implemented in commit 1144.
• Norbert Sendetzky has added support for all record types supported by PowerDNS to the LDAPBackend. Furthermore, the detection of OpenLDAP in autoconf has been improved. Finally, debian has supplied some fixes to PowerLDAP. Implemented in commit 1152 and commit 1153.
• Implemented EDNS NSID option for retrieving the nameserver ID out of band. Defaults to hostname, can be specified using the server-id setting. Code in commit 1232.
• Implemented experimental EDNS PING for enhanced forgery resilience. Code in commit 1232.

Performance:

• Improve packet generation performance, in some cases by 25%. Code at 1258, 1259.
• Improved access list checking performance. commit 1261.
• PowerDNS Authoritative caches were completely redone, and are now based on the same cache that is in the resolver. This work has been sponsored by Directi. In large benchmarks, PowerDNS performance has improved by an order of magnitude or more. This new version allows for near-instantaneous cache purging, plus very rapid purging based on suffix. Purge commands can also be batched. This work is partially based on an innovative reverse-string comparison function authored by Aki Tuomi.
• Installations which run with very high cache hitrates can now benefit from multiple CPUs by setting receiver-threads to the number of desired CPUs to utilize in cache operations. Implemented in commit 1316.
• BIND backend speedups in commit 1108, measured at around a 20% improvement, possibly more on very large setups.

Bug fixed:

• Tyler Hall discovered the PowerDNS configuration file parser had problems with trailing tabs. This turned out to be a wider problem in PowerDNS. Buggy code replaced by a library call in commit 1237 and commit 1240.
• David Apgar of Yahoo discovered that our ‘guardian’ method of restarting PowerDNS in case of problems was not fool proof, and submitted a fix. A variation of this fix can be found in commit 1323. Also reported by Directi.
• Connection reset by peer events in the TCP nameserver no longer lead to the cycling of database connections. Code in commit 1241.
• FreeBSD compilation with Generic PostgreSQL backend was fixed. Reported by Wouter de Jong of WideXS, fixed in commit 1305, closes ticket 95.
• Web server no longer prints ‘1e2%’. Finally closes ticket 26. Much friendly nagging for over 3 years by Jeff Sipek, code in commit 1303.
• PowerDNS used to ignore certain queries it could not answer. These queries are no longer ignored, but get a SERVFAIL response. Implemented in commit 1239.
• Fix subtle CNAME and wildcard interactions reported by ‘zzyzz’, implemented in commit 1147.
• The generic backends did not honor the default-ttl setting. Spotted and implemented by Matti Hiljanen.
• Matti Hiljanen discovered that the OpenDBX backend did not fill out the SOA ttl value properly. Matti also improved the SQL statements for better compatibility. Implemented in commit 1181.
• Treat invalid WWW requests better. Spotted by Maikel Verheijen, implemented in commit 1092.
• Documentation errors and typos, spotted by Marco Davids (commit 1097) and Rejo Zengers (commit 1119)
• Properly fill out the ‘recursion available’ flag. Spotted by Augie Schwer in ticket 167.
• Several memory leaks on bad data in the database or other errors have been fixed. Addressed in 1078 and 1079.
• In contravention to the documentation, the domain type as specified in the database (‘MASTER’, ‘SLAVE’ or ‘NATIVE’) was interpreted case sensitively. 1084.
• BIND backend could crash on processing information about slave zones to be checked. Spotted by Stefan Schmidt, fixed in 1089.
• Jelte Jansen of NLNetLabs Foundation discovered PowerDNS in BIND mode couldn’t operate as a root-server! Fixed in 1057.
• ‘DPS’ discovered there was a rare opportunity for PowerDNS to lock up waiting for new data. Addressed in 1076.
• Make single threaded mode more resilient against errors. commit 1272.
• DNSSEC records were part of 2.9.21, but were not actually hooked up. Please note that while PowerDNS can serve most DNSSEC records, it does not do DNSSEC processing. Implemented in 1046.
• Shawn Starr migrated all his domains to PowerDNS in one evening, from an installation that had been used since BIND4. In doing so, he found 3 bugs in as many hours. An IN statement in the BIND named.conf with a zone with a trailing dot was misparsed, fixed in commit 1233. Secondly, the zonefile parser tripped over a line consisting of nothing but comments in the wrong place. Finally ‘$ORIGIN.’ had been misparsed. Last two issues fixed in commit 1234.
• Our statistics counters did not wrap correctly after the 2.15 billion mark. Spotted by Stefan Schmidt, reported in ticket 179, fixed in commit 1284.
• Bindbackend could sometimes generate very strange error messages while processing a malformed zone file. Sometimes such error messages could cause a crash (reported on HP-UX). Addressed by commit 1279. This could not be triggered remotely. Closes ticket ticket 203.
• Pipe backend did not clean up killed coprocesses. Found and fixed by Daniel Drown
• Installations with tens of thousands of slave domains would never complete the cycle to check the freshness of all zones as each incoming notification disrupted this cycle. Addressed in cooperation with Tyler Hall of EditDNS.

Improvements:

• Zoneparser improvements mean $TTL and $INCLUDES now work a lot better. Implemented in 1056, 1062.
• No longer report temporary recvfopenDBX so that SQLite reads and writes no longer deadlock, plus compliation fixes on Solaris, plus the addition of autoserials to backends that support triggers. Implemented in commit 1154.
• Random generator is now based on AES, improving the security of certain proxy operations. This is the same random generator that is in the recursor. Implemented in commit 1256.
• Documentation for ‘supermaster’ mode was improved due to popular demand.
• When binding to a UDP port failed, supply a more precise error message (commit 1245)
• The zoneparser error messages were vastly improved, partially inspired by Shawn’s cowboy migration. Code in commit 1235.
• Labels are compressed more efficiently (case-insensitively), leading to smaller packets. Implemented in commit 1156.
• Fix handling of TCP timeouts to not cause a reload of the backends. Implemented in commit 1092.
• TCP Receiver no longer spams the log with common network errors. Implemented in commit 1306.
• Move from select() to poll()-based multiplexing, allowing PowerDNS to listen on more than 1024 sockets simultaneously. One big PowerDNS user needs this. Implemented in 1072.
• Zone2sql now reads source files in performance enhancing inode order. Additionally, zone2sql no longer dies on a missing zone file if –on-error-resume-next was specified. Finally, statistics of zone2sql conversion have been improved. Implemented in 1055.
• Address issues found by more recent g++ versions. Spotted and/or fixed by Jorn Ekkelenkamp (commit 1051), Marcus Rueckert (commit 1094), Norbert Sendetzky (commit 1107), Serge Belyshev (commit 1171).
• The Intel C Compiler implements certain things differently, causing the master/slave communicator to malfunction. Spotted by Marcus Rueckert, implemented in 1052, plus fallout in 1105.
• PowerDNS can now be compiled with Boost 1.3