path: root/ares/CHANGES

  Changelog for the c-ares project

* June 8 2009 (Yang Tse)
- Removed buildconf.bat from release and daily snapshot archives. This
  file is only for CVS tree checkout builds.

* May 26 2009 (Yang Tse)
- Added --enable-curldebug configure option to enable and disable building
  with the low-level curl debug memory tracking 'feature' to allow decoupled
  setting from --enable-debug, allowing again to build c-ares independently
  out of the CVS tree.

* May 19 2009 (Yang Tse)
- Introduced ares_library_init() and ares_library_cleanup() functions.

  This is an API and ABI break for Win32/64 systems. Non-Win32/64 build targets
  using c-ares 1.6.1 can still survive without calling these functions. Read all
  the details on ares_library_init(3) and ares_library_cleanup(3) man pages that
  are included.

  curl/libcurl 7.19.5 is fully compatible with c-ares 1.6.1 on all systems.

  In order to use c-ares 1.6.1 with curl/libcurl on Win32/64 systems it is
  required that curl/libcurl is 7.19.5 or newer. In other words, it is not
  possible on Win32/64 to use c-ares 1.6.1 with a curl/libcurl version less
  than 7.19.5

* May 11 2009 (Daniel Stenberg)
- Gregor Jasny made c-ares link with libtool 's -export-symbols-regex option to
  only expose functions starting with ares_.

* May 2 2009 (Yang Tse)
- Use a build-time configured ares_socklen_t data type instead of socklen_t.

* April 21 2009 (Yang Tse)
- Moved potential inclusion of system's malloc.h and memory.h header files to
  setup_once.h.  Inclusion of each header file is based on the definition of
  NEED_MALLOC_H and NEED_MEMORY_H respectively.

* March 11 2009 (Yang Tse)
- Japheth Cleaver fixed acountry.c replacing u_long with unsigned long.

* February 20 2009 (Yang Tse)
- Do not halt compilation when using VS2008 to build a Windows 2000 target.

* February 3 2009 (Phil Blundell)
- If the server returns garbage or nothing at all in response to an AAAA query,
  go on and ask for A records anyway.

* January 31 2009 (Daniel Stenberg)
- ares_gethostbyname() now accepts 'AF_UNSPEC' as a family for resolving
  either AF_INET6 or AF_INET. It works by accepting any of the looksups in the
  hosts file, and it resolves the AAAA field with a fallback to A.

* January 14 2009 (Daniel Stenberg)
- ares.h no longer uses the HAVE_STRUCT_IN6_ADDR define check, but instead it
  now declares the private struct ares_in6_addr for all systems instead of
  relying on one possibly not present in the system.

* January 13 2009 (Phil Blundell)
- ares__send_query() now varies the retry timeout pseudo-randomly to avoid
  packet storms when several queries were started at the same time.

* January 11 2009 (Daniel Stenberg)
- Phil Blundell added the internal function ares__expand_name_for_response()
  that is now used by the ares_parse_*_reply() functions instead of the
  ares_expand_name() simply to easier return ARES_EBADRESP for the cases where
  the name expansion fails as in responses that really isn't expected.

Version 1.6.0 (Dec 9, 2008)

* December 9 2008 (Gisle Vanem)

  Fixes for Win32 targets using the Watt-32 tcp/ip stack.

* Dec 4 2008 (Daniel Stenberg)

  Gregor Jasny provided the patch that introduces ares_set_socket_callback(),
  and I edited it to also get duped by ares_dup().

* Dec 3 2008 (Daniel Stenberg)

  API changes:

  I made sure the public ares_config struct looks like before and yet it
  supports the ROTATE option thanks to c-ares now storing the "optmask"
  internally. Thus we should be ABI compatible with the past release(s)
  now. My efforts mentioned below should not break backwards ABI compliance.

  Here's how I suggest we proceed with the API:

  ares_init() will be primary "channel creator" function.

  ares_init_options() will continue to work exactly like now and before. For
  starters, it will be the (only) way to set the existing options.

  ares_save_options() will continue to work like today, but will ONLY save
  options that you can set today (including ARES_OPT_ROTATE actually) but new
  options that we add may not be saved with this.

  Instead we introduce:

  ares_dup() that instead can make a new channel and clone the config used
  from an existing channel. It will then clone all config options, including
  future new things we add.

  ares_set_*() style functions that set (new) config options. As a start we
  simply add these for new functionality, but over time we can also introduce
  them for existing "struct ares_options" so that we can eventually deprecate
  the two ares_*_options() functions.

  ares_get_*() style functions for extracting info from a channel handle that
  should be used instead of ares_save_options().

* Nov 26 2008 (Yang Tse)
- Brad Spencer provided changes to allow buildconf to work on OS X.

- Gerald Combs fixed a bug in ares_parse_ptr_reply() which would cause a
  buffer to shrink instead of expand if a reply contained 8 or more records.

* Nov 25 2008 (Yang Tse)
- In preparation for the upcomming IPv6 nameservers patch, the internal
  ares_addr union is now changed into an internal struct which also holds
  the address family.

* Nov 19 2008 (Daniel Stenberg)
- Brad Spencer brought the new function ares_gethostbyname_file() which simply
  resolves a host name from the given file, using the regular hosts syntax.

* Nov 1 2008 (Daniel Stenberg)
- Carlo Contavalli added support for the glibc "rotate" option, as documented
  in man resolv.conf:

  causes round robin selection of nameservers from among those listed.  This
  has the effect of spreading the query load among all listed servers, rather
  than having all clients try the first listed server first every time.

  You can enable it with ARES_OPT_ROTATE

* Oct 21 2008 (Yang Tse)
  Charles Hardin added handling of EINPROGRESS for UDP connects.

* Oct 18 2008 (Daniel Stenberg)
  Charles Hardin made adig support a regular numerical dotted IP address for the
  -s option as well.

* Oct 7 2008 (Yang Tse)
- Added --enable-optimize configure option to enable and disable compiler
  optimizations to allow decoupled setting from --enable-debug.

* Oct 2 2008 (Yang Tse)
- Added --enable-warnings configure option to enable and disable strict
  compiler warnings to allow decoupled setting from --enable-debug.

* Sep 17 2008 (Yang Tse)
- Code reorganization to allow internal/private use of "nameser.h" to any
  system that lacks arpa/nameser.h or arpa/nameser_compat.h header files.

* Sep 16 2008 (Yang Tse)
- Code reorganization to allow internal/private use of ares_writev to any
  system that lacks the writev function.

* Sep 15 2008 (Yang Tse)
- Code reorganization to allow internal/private use of ares_strcasecmp to any
  system that lacks the strcasecmp function.

- Improve configure detection of some string functions.

* Sep 11 2008 (Yang Tse)
- Code reorganization to allow internal/private use of ares_strdup to any
  system that lacks the strdup function.

Version 1.5.3 (Aug 29, 2008)

* Aug 25 2008 (Yang Tse)
- Improvement by Brad House:

  This patch addresses an issue in which a response could be sent back to the
  source port of a client from a different address than the request was made to.
  This is one form of a DNS cache poisoning attack.

  The patch simply uses recvfrom() rather than recv() and validates that the
  address returned from recvfrom() matches the address of the server we have
  connected to. Only necessary on UDP sockets as they are connection-less, TCP
  is unaffected.

- Fix by George Neill:
  Fixed compilation of acountry sample application failure on some systems.

* Aug 4 2008 (Daniel Stenberg)
- Fix by Tofu Linden:

  The symptom:
  * Users (usually, but not always) on 2-Wire routers and the Comcast service
  and a wired connection to their router would find that the second and
  subsequent DNS lookups from fresh processes using c-ares to resolve the same
  address would cause the process to never see a reply (it keeps polling for
  around 1m15s before giving up).

  The repro:
  * On such a machine (and yeah, it took us a lot of QA to find the systems
  that reproduce such a specific problem!), do 'ahost www.secondlife.com',
  then do it again.  The first process's lookup will work, subsequent lookups
  will time-out and fail.

  The cause:
  * init_id_key() was calling randomize_key() *before* it initialized
  key->state, meaning that the randomness generated by randomize_key() is
  immediately overwritten with deterministic values. (/dev/urandom was also
  being read incorrectly in the c-ares version we were using, but this was
  fixed in a later version.)
  * This makes the stream of generated query-IDs from any new c-ares process
  be an identical and predictable sequence of IDs.
  * This makes the 2-Wire's default built-in DNS server detect these queries
  as probable-duplicates and (erroneously) not respond at all.


* Aug 4 2008 (Yang Tse)
- Autoconf 2.62 has changed the behaviour of the AC_AIX macro which we use.
  Prior versions of autoconf defined _ALL_SOURCE if _AIX was defined. 2.62
  version of AC_AIX defines _ALL_SOURCE and other four preprocessor symbols
  no matter if the system is AIX or not. To keep the traditional behaviour,
  and an uniform one across autoconf versions AC_AIX is replaced with our
  own internal macro CARES_CHECK_AIX_ALL_SOURCE.

* Aug 1 2008 (Yang Tse)
- Configure process now checks if the preprocessor _REENTRANT symbol is already
  defined. If it isn't currently defined a set of checks are performed to test
  if its definition is required to make visible to the compiler a set of *_r
  functions. Finally, if _REENTRANT is already defined or needed it takes care
  of making adjustments necessary to ensure that it is defined equally for the
  configure process tests and generated config file.

* Jul 20 2008 (Yang Tse)
- When recvfrom prototype uses a void pointer for arguments 2, 5 or 6 this will
  now cause the definition, as appropriate, of RECVFROM_TYPE_ARG2_IS_VOID,
  RECVFROM_TYPE_ARG5_IS_VOID or RECVFROM_TYPE_ARG6_IS_VOID.

* Jul 17 2008 (Yang Tse)
- RECVFROM_TYPE_ARG2, RECVFROM_TYPE_ARG5 and RECVFROM_TYPE_ARG6 are now defined
  to the data type pointed by its respective argument and not the pointer type.

* Jul 16 2008 (Yang Tse)
- Improved configure detection of number of arguments for getservbyport_r.
  Detection is now based on compilation checks instead of linker ones.

- Configure process now checks availability of recvfrom() socket function and
  finds out its return type and the types of its arguments. Added definitions
  for non-configure systems config files, and introduced macro sreadfrom which
  will be used on udp sockets as a recvfrom() wrapper in the future.

* Jul 15 2008 (Yang Tse)
- Introduce definition of _REENTRANT symbol in setup.h to improve library
  usability.  Previously the configure process only used the AC_SYS_LARGEFILE
  macro for debug builds, now it is also used for non-debug ones enabling the
  use of configure options --enable-largefile and --disable-largefile which
  might be needed for library compatibility.  Remove checking the size of
  curl_off_t, it is no longer needed.

* Jul 3 2008 (Daniel Stenberg)
- Phil Blundell: If you ask ares_gethostbyname() to do an AF_INET6 lookup and
  the target host has only A records, it automatically falls back to an
  AF_INET lookup and gives you the A results.  However, if the target host has
  a CNAME record, this behaviour is defeated since the original query does
  return some data even though ares_parse_aaa_reply() doesn't consider it
  relevant. Here's a small patch to make it behave the same with and without
  the CNAME.

* Jul 2 2008 (Yang Tse)
- Fallback to gettimeofday when monotonic clock is unavailable at run-time.

* Jun 30 2008 (Daniel Stenberg)

- As was pointed out to me by Andreas Schuldei, the MAXHOSTNAMELEN define is
  not posix or anything and thus c-ares failed to build on hurd (and possibly
  elsewhere). The define was also somewhat artificially used in the windows
  port. Now, I instead rewrote the use of gethostbyname to enlarge the host
  name buffer in case of need and totally avoid the use of the MAXHOSTNAMELEN
  define. I thus also removed the defien from the namser.h file where it was
  once added for the windows build.

  I also fixed init_by_defaults() function to not leak memory in case if
  error.

* Jun 9 2008 (Yang Tse)

- Make libcares.pc generated file for pkg-config include information relative
  to the libraries needed for the static linking of c-ares.

* May 30 2008 (Yang Tse)

- Brad House fixed a missing header file inclusion in adig sample program.

Version 1.5.2 (May 29, 2008)

* May 13 2008 (Daniel Stenberg)

- Introducing millisecond resolution support for the timeout option. See
  ares_init_options()'s ARES_OPT_TIMEOUTMS.

* May 9 2008 (Yang Tse)

- Use monotonic time source if available, for private function ares__tvnow()

* May 7 2008 (Daniel Stenberg)

- Sebastian made c-ares able to return all PTR-records when doing reverse
  lookups. It is not common practice to have multiple PTR-Records for a single
  IP, but its perfectly legal and some sites have those.

- Doug Goldstein provided a configure patch: updates autoconf 2.13 usage to
  autoconf 2.57 usage (which is the version you have specified as the minimum
  version). It's a minor change but it does clean up some warnings with newer
  autoconf (specifically 2.62).

* May 5 2008 (Yang Tse)

- Improved parsing of resolver configuration files.

* April 4 2008 (Daniel Stenberg)

- Eino Tuominen improved the code when a file is used to seed the randomizer.

- Alexey Simak made adig support NAPTR records

- Alexey Simak fixed the VC dsp file by adding the missing source file
  ares_expand_string.c

* December 11 2007 (Gisle Vanem)

- Added another sample application; acountry.c which converts an
  IPv4-address(es) and/or host-name(s) to country-name and country-code.
  This uses the service of the DNSBL at countries.nerd.dk.

* December 3 2007 (Daniel Stenberg)

- Brad Spencer fixed the configure script to assume that there's no
  /dev/urandom when built cross-compiled as then the script cannot check for
  it.

- Erik Kline cleaned up ares_gethostbyaddr.c:next_lookup() somewhat

Version 1.5.1 (Nov 21, 2007)

* November 21 2007 (Daniel Stenberg)

- Robin Cornelius pointed out that ares_llist.h was missing in the release
  archive for 1.5.0

Version 1.5.0 (Nov 21, 2007)

* October 2 2007 (Daniel Stenberg)

- ares_strerror() segfaulted if the input error number was out of the currently
  supported range.

- Yang Tse: Avoid a segfault when generating a DNS "Transaction ID" in
  internal function init_id_key() under low memory conditions.

* September 28 2007 (Daniel Stenberg)

- Bumped version to 1.5.0 for next release and soname bumped to 2 due to ABI
  and API changes in the progress callback (and possibly more coming up from
  Steinar)

* September 28 2007 (Steinar H. Gunderson)

- Don't skip a server if it's the only one. (Bugfix from the Google tree.)

- Made the query callbacks receive the number of timeouts that happened during
  the execution of a query, and updated documentation accordingly. (Patch from
  the Google tree.)

- Support a few more socket options: ARES_OPT_SOCK_SNDBUF and
  ARES_OPT_SOCK_RCVBUF

- Always register for TCP events even if there are no outstanding queries, as
  the other side could always close the connection, which is a valid event
  which should be responded to.

* September 22 2007 (Daniel Stenberg)

- Steinar H. Gunderson fixed: Correctly clear sockets from the fd_set on in
  several functions (write_tcp_data, read_tcp_data, read_udp_packets) so that
  if it fails and the socket is closed the following code doesn't try to use
  the file descriptor.

- Steinar H. Gunderson modified c-ares to now also do to DNS retries even when
  TCP is used since there are several edge cases where it still makes sense.

- Brad House provided a fix for ares_save_options():

  Apparently I overlooked something with the ares_save_options() where it
  would try to do a malloc(0) when no options of that type needed to be saved.
  On most platforms, this was fine because malloc(0) doesn't actually return
  NULL, but on AIX it does, so ares_save_options would return ARES_ENOMEM.

* July 14 2007 (Daniel Stenberg)

- Vlad Dinulescu fixed two outstanding valgrind reports:

  1. In ares_query.c , in find_query_by_id we compare q->qid (which is a short
  int variable) with qid, which is declared as an int variable.  Moreover,
  DNS_HEADER_SET_QID is used to set the value of qid, but DNS_HEADER_SET_QID
  sets only the first two bytes of qid. I think that qid should be declared as
  "unsigned short" in this function.

  2. The same problem occurs in ares_process.c, process_answer() .  query->qid
  (an unsigned short integer variable) is compared with id, which is an
  integer variable. Moreover, id is initialized from DNS_HEADER_QID which sets
  only the first two bytes of id. I think that the id variable should be
  declared as "unsigned short" in this function.

  Even after declaring these variables as "unsigned short", the valgrind
  errors are still there. Which brings us to the third problem.

  3. The third problem is that Valgrind assumes that query->qid is not
  initialised correctly. And it does that because query->qid is set from
  DNS_HEADER_QID(qbuf); Valgrind says that qbuf has unitialised bytes. And
  qbuf has uninitialised bytes because of channel->next_id . And next_id is
  set by ares_init.c:ares__generate_new_id() . I found that putting short r=0
  in this function (instead of short r) makes all Valgrind warnings go away.
  I have studied ares__rc4() too, and this is the offending line:

        buffer_ptr[counter] ^= state[xorIndex];   (ares_query.c:62)

  This is what triggers Valgrind.. buffer_ptr is unitialised in this function,
  and by applying ^= on it, it remains unitialised.

Version 1.4.0 (June 8, 2007)

* June 4 2007 (Daniel Stenberg)

- James Bursa reported a major memory problem when resolving multi-IP names
  and I found and fixed the problem. It was added by Ashish Sharma's patch
  two days ago.

  When I then tried to verify multiple entries in /etc/hosts after my fix, I
  got another segfault and decided this code was not ripe for inclusion and I
  reverted the patch.

* June 2 2007

- Brad Spencer found and fixed three flaws in the code, found with the new
  gcc 4.2.0 warning: -Waddress

- Brad House fixed VS2005 compiler warnings due to time_t being 64bit.
  He also made recent Microsoft compilers use _strdup() instead of strdup().

- Brad House's man pages for ares_save_options() and ares_destroy_options()
  were added.

- Ashish Sharma provided a patch for supporting multiple entries in the
  /etc/hosts file. Patch edited for coding style and functionality by me
  (Daniel).

* May 30 2007

- Shmulik Regev brought cryptographically secure transaction IDs:

  The c-ares library implementation uses a DNS "Transaction ID" field that is
  seeded with a pseudo random number (based on gettimeofday) which is
  incremented (++) between consecutive calls and is therefore rather
  predictable. In general, predictability of DNS Transaction ID is a well
  known security problem (e.g.
  http://bak.spc.org/dms/archive/dns_id_attack.txt) and makes a c-ares based
  implementation vulnerable to DNS poisoning. Credit goes to Amit Klein
  (Trusteer) for identifying this problem.

  The patch I wrote changes the implementation to use a more secure way of
  generating unique IDs. It starts by obtaining a key with reasonable entropy
  which is used with an RC4 stream to generate the cryptographically secure
  transaction IDs.

  Note that the key generation code (in ares_init:randomize_key) has two
  versions, the Windows specific one uses a cryptographically safe function
  provided (but undocumented :) by the operating system (described at
  http://blogs.msdn.com/michael_howard/archive/2005/01/14/353379.aspx).  The
  default implementation is a bit naive and uses the standard 'rand'
  function. Surely a better way to generate random keys exists for other
  platforms.

  The patch can be tested by using the adig utility and using the '-s' option.

- Brad House added ares_save_options() and ares_destroy_options() that can be
  used to keep options for later re-usal when ares_init_options() is used.

  Problem: Calling ares_init() for each lookup can be unnecessarily resource
         intensive.  On windows, it must LoadLibrary() or search the registry
         on each call to ares_init().  On unix, it must read and parse
         multiple files to obtain the necessary configuration information.  In
         a single-threaded environment, it would make sense to only
         ares_init() once, but in a heavily multi-threaded environment, it is
         undesirable to ares_init() and ares_destroy() for each thread created
         and track that.

  Solution: Create ares_save_options() and ares_destroy_options() functions to
         retrieve and free options obtained from an initialized channel.  The
         options populated can be used to pass back into ares_init_options(),
         it should populate all needed fields and not retrieve any information
         from the system.  Probably wise to destroy the cache every minute or
         so to prevent the data from becoming stale.

- Daniel S added ares_process_fd() to allow applications to ask for processing
  on specific sockets and thus avoiding select() and associated
  functions/macros.  This function will be used by upcoming libcurl releases
  for this very reason. It also made me export the ares_socket_t type in the
  public ares.h header file, since ares_process_fd() uses that type for two of
  the arguments.

* May 25 2007

- Ravi Pratap fixed a flaw in the init_by_resolv_conf() function for windows
  that could cause it to return a bad return code.

* April 16 2007

- Yang Tse: Provide ares_getopt() command-line parser function as a source
  code helper function, not belonging to the actual c-ares library.

* February 19 2007

- Vlad Dinulescu added ares_parse_ns_reply().

* February 13 2007

- Yang Tse: Fix failure to get the search sequence of /etc/hosts and
  DNS from /etc/nsswitch.conf, /etc/host.conf or /etc/svc.conf when
  /etc/resolv.conf did not exist or was unable to read it.

* November 22 2006

- Install ares_dns.h too

- Michael Wallner fixed this problem: When I set domains in the options
  struct, and there are domain/search entries in /etc/resolv.conf, the domains
  of the options struct will be overridden.

* November 6 2006

- Yang Tse removed a couple of potential zero size memory allocations.

- Andreas Rieke fixed the line endings in the areslib.dsp file that I (Daniel)
  broke in the 1.3.2 release. We should switch to a system where that file is
  auto-generated. We could rip some code for that from curl...

Version 1.3.2 (November 3, 2006)

* October 12 2006

- Prevent ares_getsock() to overflow if more than 16 sockets are used.

* September 11 2006

- Guilherme Balena Versiani: I noted a strange BUG in Win32 port
  (ares_init.c/get_iphlpapi_dns_info() function): when I disable the network
  by hand or disconnect the network cable in Windows 2000 or Windows XP, my
  application gets 127.0.0.1 as the only name server. The problem comes from
  'GetNetworkParams' function, that returns the empty string "" as the only
  name server in that case. Moreover, the Windows implementation of
  inet_addr() returns INADDR_LOOPBACK instead of INADDR_NONE.

* August 29 2006

- Brad Spencer did

  o made ares_version.h use extern "C" for c++ compilers
  o fixed compiler warnings in ares_getnameinfo.c
  o fixed a buffer position init for TCP reads

* August 3 2006

- Ravi Pratap fixed ares_getsock() to actually return the proper bitmap and
  not always zero!

Version 1.3.1 (June 24, 2006)

* July 23, 2006

- Gisle Vanem added getopt() to the ahost program. Currently accepts
  only [-t {a|aaaa}] to specify address family in ares_gethostbyname().

* June 19, 2006

- (wahern) Removed "big endian" DNS section and RR data integer parser
  macros from ares_dns.h, which break c-ares on my Sparc64. Bit-wise
  operations in C operate on logical values. And in any event the octets are
  already in big-endian (aka network) byte order so they're being reversed
  (thus the source of the breakage).

* June 18, 2006

- William Ahern handles EAGAIN/EWOULDBLOCK errors in most of the I/O calls
  from area_process.c.

  TODO: Handle one last EAGAIN for a UDP socket send(2) in
  ares__send_query().

* May 10, 2006

- Bram Matthys brought my attention to a libtool peculiarity where detecting
  things such as C++ compiler actually is a bad thing and since we don't need
  that detection I added a work-around, much inspired by a previous patch by
  Paolo Bonzini. This also shortens the configure script quite a lot.

* May 3, 2006

- Nick Mathewson added the ARES_OPT_SOCK_STATE_CB option that when set makes
  c-ares call a callback on socket state changes. A better way than the
  ares_getsock() to get full control over the socket state.

* January 9, 2006

- Alexander Lazic improved the getservbyport_r() configure check.

* January 6, 2006

- Alexander Lazic pointed out that the buildconf should use the ACLOCAL_FLAGS
  variable for easier controlling what it does and how it runs.

* January 5, 2006

- James Bursa fixed c-ares to find the hosts file on RISC OS, and made it
  build with newer gcc versions that no longer defines "riscos".

* December 22

- Daniel Stenberg added ares_getsock() that extracts the set of sockets to
  wait for action on. Similar to ares_fds() but not restricted to using
  select() for the waiting.

* November 25

- Yang Tse fixed some send() / recv() compiler warnings

* September 18

- Added constants that will be used by ares_getaddrinfo

- Made ares_getnameinfo use the reentrant getservbyport (getservbyport_r) if it
  is available to ensure it works properly in a threaded environment.

* September 10

- configure fix for detecting a member in the sockaddr_in6 struct which failed
  on ipv6-enabled HP-UX 11.00

Version 1.3.0 (August 29, 2005)

* August 21

- Alfredo Tupone provided a fix for the Windows code in get_iphlpapi_dns_info()
  when getting the DNS server etc.

* June 19

- Added some checks for the addrinfo structure.

* June 2

- William Ahern:

  Make UDP sockets non-blocking. I've confirmed that at least on Linux 2.4 a
  read event can come back from poll() on a valid SOCK_DGRAM socket but
  recv(2) will still block. This patch doesn't ignore EAGAIN in
  read_udp_packets(), though maybe it should. (This patch was edited by Daniel
  Stenberg and a new configure test was added (imported from curl's configure)
  to properly detect what non-blocking socket approach to use.)

  I'm not quite sure how this was happening, but I've been seeing PTR queries
  which seem to return empty responses. At least, they were empty when calling
  ares_expand_name() on the record. Here's a patch which guarantees to
  NUL-terminate the expanded name. The old behavior failed to NUL-terminate if
  len was 0, and this was causing strlen() to run past the end of the buffer
  after calling ares_expand_name() and getting ARES_SUCCESS as the return
  value. If q is not greater than *s then it's equal and *s is always
  allocated with at least one byte.

* May 16

- Added ares_getnameinfo which mimics the getnameinfo API (another feature
  that could use testing).

* May 14

- Added an inet_ntop function from BIND for systems that do not have it.

* April 9

- Made sortlist support IPv6 (this can probably use some testing).

- Made sortlist support CIDR matching for IPv4.

* April 8

- Added preliminary IPv6 support to ares_gethostbyname. Currently, sortlist
  does not work with IPv6. Also provided an implementation of bitncmp from
  BIND for systems that do not supply this function. This will be used to add
  IPv6 support to sortlist.

- Made ares_gethostbyaddr support IPv6 by specifying AF_INET6 as the family.
  The function can lookup IPv6 addresses both from files (/etc/hosts) and
  DNS lookups.

* April 7

- Tupone Alfredo fixed includes of arpa/nameser_compat.h to build fine on Mac
  OS X.

* April 5

- Dominick Meglio: Provided implementations of inet_net_pton and inet_pton
  from BIND for systems that do not include these functions.

* March 11, 2005

- Dominick Meglio added ares_parse_aaaa_reply.c and did various
  adjustments. The first little steps towards IPv6 support!

* November 7

- Fixed the VC project and makefile to use ares_cancel and ares_version

* October 24

- The released ares_version.h from 1.2.1 says 1.2.0 due to a maketgz flaw.
  This is now fixed.

Version 1.2.1 (October 20, 2004)

* September 29

- Henrik Stoerner fix: got a report that Tru64 Unix (the unix from Digital
  when they made Alpha's) uses /etc/svc.conf for the purpose fixed below for
  other OSes. He made c-ares check for and understand it if present.

- Now c-ares will use local host name lookup _before_ DNS resolving by default
  if nothing else is told.

* September 26

- Henrik Stoerner: found out that c-ares does not look at the /etc/host.conf
  file to determine the sequence in which to search /etc/hosts and DNS.  So on
  systems where this order is defined by /etc/host.conf instead of a "lookup"
  entry in /etc/resolv.conf, c-ares will always default to looking in DNS
  first, and /etc/hosts second.

  c-ares now looks at

  1) resolv.conf (for the "lookup" line);
  2) nsswitch.fon (for the "hosts:" line);
  3) host.conf (for the "order" line).

  First match wins.

- Dominick Meglio patched: C-ares on Windows assumed that the HOSTS file is
  located in a static location. It assumed
  C:\Windows\System32\Drivers\Etc. This is a poor assumption to make. In fact,
  the location of the HOSTS file can be changed via a registry setting.

  There is a key called DatabasePath which specifies the path to the HOSTS
  file:
  http://www.microsoft.com/technet/itsolutions/network/deploy/depovg/tcpip2k.mspx

  The patch will make c-ares correctly consult the registry for the location
  of this file.

* August 29

- Gisle Vanem fixed the MSVC build files.

* August 20

- Gisle Vanem made c-ares build and work with his Watt-32 TCP/IP stack.

* August 13

- Harshal Pradhan made a minor syntax change in ares_init.c to make it build
  fine with MSVC 7.1

* July 24

- Made the lib get built static only if --enable-debug is used.

- Gisle Vanem fixed:

  Basically in loops like handle_errors(), 'query->next' was assigned a local
  variable and then query was referenced after the memory was freed by
  next_server(). I've changed that so next_server() and end_query() returns
  the next query. So callers should use this ret-value.

  The next problem was that 'server->tcp_buffer_pos' had a random value at
  entry to 1st recv() (luckily causing Winsock to return ENOBUFS).

  I've also added a ares_writev() for Windows to streamline the code a bit
  more.

* July 20
- Fixed a few variable return types for some system calls. Made configure
  check for ssize_t to make it possible to use that when receiving the send()
  error code. This is necessary to prevent compiler warnings on some systems.

- Made configure create config.h, and all source files now include setup.h that
  might include the proper config.h (or a handicrafted alternative).

- Switched to 'ares_socket_t' type for sockets in ares, since Windows don't
  use 'int' for that.

- automake-ified and libool-ified c-ares. Now it builds libcares as a shared
  lib on most platforms if wanted. (This bloated the size of the release
  archive with another 200K!)

- Makefile.am now uses Makefile.inc for the c sources, h headers and man
  pages, to make it easier for other makefiles to use the exact same set of
  files.

- Adjusted 'maketgz' to use the new automake magic when building distribution
  archives.

- Anyone desires HTML and/or PDF versions of the man pages in the release
  archives?

* July 3
- Günter Knauf made c-ares build and run on Novell Netware.

* July 1
- Gisle Vanem provided Makefile.dj to build with djgpp, added a few more djgpp
  fixes and made ares not use 'errno' to provide further info on Windows.

* June 30
- Gisle Vanem made it build with djgpp and run fine with the Watt-32 stack.

* June 10
- Gisle Vanem's init patch for Windows:

  The init_by_resolv_conf() function fetches the DNS-server(s)
  from a series of registry branches.

  This can be wrong in the case where DHCP has assigned nameservers, but the
  user has overridden these servers with other prefered settings. Then it's
  wrong to use the DHCPNAMESERVER setting in registry.

  In the case of no global DHCP-assigned or fixed servers, but DNS server(s)
  per adapter, one has to query the adapter branches.  But how can c-ares know
  which adapter is valid for use? AFAICS it can't. There could be one adapter
  that is down (e.g. a VPN adapter).

  So it's better to leave this to the IP Helper API (iphlapi) available in
  Win-98/2000 and later. My patch falls-back to the old way if not available.

* June 8
- James Bursa fixed an init issue for RISC OS.

* May 11
- Nico Stappenbelt reported that when processing domain and search lines in
  the resolv.conf file, the first entry encountered is processed and used as
  the search list. According to the manual pages for both Linux, Solaris and
  Tru64, the last entry of either a domain or a search field is used.

  This is now adjusted in the code

Version 1.2.0 (April 13, 2004)

* April 2, 2004
- Updated various man pages to look nicer when converted to HTML on the web
  site.

* April 1, 2004
- Dirk Manske provided a new function that is now named ares_cancel(). It is
  used to cancel/cleanup a resolve/request made using ares functions on the
  given ares channel. It does not destroy/kill the ares channel itself.

- Dominick Meglio cleaned up the formatting in several man pages.

* March 30, 2004
- Dominick Meglio's new ares_expand_string. A helper function when decoding
  incoming DNS packages.

- Daniel Stenberg modified the Makefile.in to use a for loop for the man page
  installation to improve overview and make it easier to add man pages.

Version 1.1.0 (March 11, 2004)

* March 9, 2004
- Gisle Vanem improved build on Windows.

* February 25, 2004
- Dan Fandrich found a flaw in the Feb 22 fix.

- Added better configure --enable-debug logic (taken from the curl configure
  script). Added acinclude.m4 to the tarball.

* February 23, 2004
- Removed ares_free_errmem(), the function, the file and the man page. It was
  not used and it did nothing.

- Fixed a lot of code that wasn't "64bit clean" and thus caused a lot of
  compiler warnings on picky compilers.

* February 22, 2004
- Dominick Meglio made ares init support multiple name servers in the
  NameServer key on Windows.

* February 16, 2004
- Modified ares_private.h to include libcurl's memory debug header if
  CURLDEBUG is set. This makes all the ares-functions supervised properly by
  the curl test suite. This also forced me to add inclusion of the
  ares_private.h header in a few more files that are using some kind of
  memory-related resources.

- Made the makefile only build ahost and adig if 'make demos' is used.

* February 10, 2004
- Dirk Manske made ares_version.h installed with 'make install'

* February 4, 2004
- ares_free_errmem() is subject for removal, it is simply present for future
  purposes, and since we removed the extra parameter in strerror() it won't
  be used by c-ares!
- configure --enable-debug now enables picky compiler options if gcc is used
- fixed several compiler warnings --enable-debug showed and Joerg Mueller-Tolk
  reported

Version 1.0.0 (February 3, 2004)

* February 3, 2004
- now we produce the libcares.a library instead of the previous libares.a
  since we are no longer compatible

* February 2, 2004

- ares_strerror() has one argument less. This is the first official
  modification of the existing provided ares API.

* January 29, 2004

- Dirk Manske fixed how the socket is set non-blocking.

* January 4, 2004

- Dominick Meglio made the private gettimeofday() become ares_gettimeofday()
  instead in order to not pollute the name space and risk colliding with
  other libraries' versions of this function.

* October 24, 2003. Daniel Stenberg

  Added ares_version().

Version 1.0-pre1 (8 October 2003)

- James Bursa made it run on RISC OS

- Dominick Meglio made it run fine on NT4

- Duncan Wilcox made it work fine on Mac OS X

- Daniel Stenberg adjusted the windows port

- liren at vivisimo.com made the initial windows port

* Imported the sources from ares 1.1.1