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.
Prior versions of autoconf defined _ALL_SOURCE if _AIX was defined. But,
autoconf 2.62 version of AC_AIX defines _ALL_SOURCE along with other four
preprocessor symbols no matter if the system is AIX or not. To keep the
traditional behaviour, as well as an uniform one, across autoconf versions
AC_AIX is replaced with our own internal macro.
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.
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.
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.
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).
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.
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.
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.
Yang Tse