dnsproxy uses sendmsg instead of sendto
dnsproxy.cc and nameserver.cc use addCMsgSrcAddr() to add a source address control message before sendmsg
remove some unused variables from gsqlbackend
cleanup hmac calculation functions
Merge pull request #1123 from mind04/coverity

some by coverity inspired cleanup
send +CD in recursive nsec3dig, requested by Marco Davids
fix lua 5.2 version check in luabackend
re-fix compilation for new polarssl
make luabackend respect LUA_LIBS instead of forcing -llua5.1
remotebackend libcurl linking
Merge pull request #1126 from mind04/libcurl

remotebackend libcurl linking
This patch allows user to specify that socket binding can fail. On IPv4 there
is a ip_nonlocal_bind sysctl that can be set, however for IPv6 there is not
this call and it is unlikely to be implemented kernel-side.

Fixes PowerDNS/pdns#344
fixes PowerDNS/pdns/657

I noticed this as a result of the changes in 3.2 whereby each receiver gets its own distributor - whenever the dynhandler calls ->getBackend() it will only find the one in its' current thread, so reload won't propergate to backends within other threads.

However, I suspect this condition has always been around as a race - if I have multiple distributors and I call reload; one thread is issuing reloads while all the other backend threads are currently executing (potentially). I guess if you call reload in previous versions on a highly loaded server with multiple backends you could probably get it to crash.

The attached patch changes it so that each backend has a variable which is changed to signal that a reload or rediscover has been requested. When processing gets to an appropriate point ie before it next queries the backend database, such an operation will be run. Note that it is not run in ::get as we don't want a backend to be reloaded between performing a lookup and getting the records.

This patch means that reload/reinitialize are not done straight away as in previous versions, but on a moderately loaded server this should not be a problem as they will be performed the next time a backend is called.
fixes PowerDNS/pdns#650

The attached patch changes the distributor code in the following ways:

1) Remove (as far as i can see) unused functions which allow for the fetching of the answer from an answers queue. I struggle to understand why this would ever be useful compared to having a callback; it also reduces code complexity and removes some locks. Also allows (2):
2) Split into 3 classes - the new ones being SingleThreadDistributor and MultiThreadDistributor - removes some of the conditional statements. It also means that in distributor-threads=1 mode, NO additional distributor threads are forked (unlike the existing code), and the class will also use less memory and generally be more efficient.

This has been tested in that the pdns server starts up and answers questions correctly in both modes, it's more of an RFC attempt to clean up the code a bit.
fixes PowerDNS/pdns/#661

I was doing some performance testing on our 32-way servers and discovered that in the simple case where the test program returns the data straight away, about 80% of the time was being spent in the kernel in a spinlock. I've been debugging this looking at the coprocess code and discovered that this is due to the following line in coprocess.cc:

setbuf(d_fp,0); // no buffering please, confuses select

If this is removed, performance in my particular test case goes from 2000qps with powerdns running at about 2000% cpu to 10000qps with powerdns using about 300% cpu.

Obviously the comment implies that this is not a permanent solution, I guess if the timeout is specified as 0 then the select code won't be executed and so you can disable the setbuf easily enough. However perhaps if the timeout is wanted you could set an alarm() rather than using select?
fixes PowerDNS/pdns#666

SO_REUSEPORT is available on various bsd operating systems as standard, and also as a linux kernel patch from Google. It allows

1) Running 2 powerdns processes concurrently so that you can restart powerdns without loosing any packets
2) (the main purpose for my writing this patch) On linux with a patched kernel removes contention from many threads using a socket. In my tests this improves performance with a packet cache from 300kqps to 1mqps

If the SO_REUSEPORT call is available, the attached patch causes each receiver thread to open a new socket for connections which allows each thread (on linux) to operate at full speed rather than waiting on a slow socket. It should fail nicely ie if the call is not available at either compile time or run time it will just use the initially created socket.

Was merged in to linux 3.9 series - see https://lwn.net/Articles/542629/ for more information
fixes PowerDNS/pdns#692

For the second time when writing a backend I forgot that an ANY query needs to return any SOA data as well. This is because we store our SOA's separately from our other DNS data in order to optimize zone lookups. According to Habbie MyDNS backend has the same bug. The attached patch basically forces an SOA to be included which is actually much more optimal than anything I can do in my backends as I don't have easy access to the knowledge of:

* sd data structure;
* is this query also an SOA

meaning that if I answer it in the backend I have to do a number of additional lookups for information that is already available in the PacketHandler. Additionally, I notice that you are basically doing all the SOA setup anyway if there is anything looking like an SOA entry. So, all this patch does is strip out any SOA entries and then insert one if there should be. This seems to me to both potentially simplify backend code and fix up any user errors more accurately than the current code does.
fixes PowerDNS/pdns#693

removes number of static variables and makes them class, also optimizes if query cache is disabled.
allow overriding MAKE in regression tests
presumably fix building on os x 10.9, thanks @mactijn