Some android systems like ARM64 may not have the __system_property_get
symbol in libc (but still have it in the public headers). Detect this
condition at build time. The __system_property_get method of retrieving
name servers is deprecated as of Oreo so should strictly be a fallback
mechanism anyhow.
Socklen_t should not be used in code, instead ares_socklen_t should be used.
Convert ssize_t to ares_ssize_t for portability since the public API now exposes this.
Original Patch From Brad Spencer:
https://c-ares.haxx.se/mail/c-ares-archive-2016-04/0000.shtml
My modifications include:
* Dynamically find GetBestRoute2 since it is a Windows Vista+ symbol, and will fall back to prior behavior when not available.
* Prefer get_DNS_AdaptersAddresses as the modifications should alleviate the concerns which caused us to prefer get_DNS_NetworkParams
* Update AppVeyor to use MinGW-w64 instead of the legacy MinGW
* Fix compile error in test suite for Windows.
Original message from patch below:
From: Brad Spencer <bspencer@blackberry.com>
Date: Fri, 29 Apr 2016 14:26:23 -0300
On Windows, the c-ares DNS resolver tries first to get a full list of
DNS server addresses by enumerating the system's IPv4/v6 interfaces and
then getting the per-interface DNS server lists from those interfaces
and joining them together. The OS, at least in the way the c-ares
prefers to query them (which also may be the only or best way in some
environments), does not provide a unified list of DNS servers ordered
according to "current network conditions". Currently, c-ares will then
try to use them in whatever order the nested enumeration produces, which
may result in DNS requests being sent to servers on one interface
(hosting the current default route, for example) that are only intended
to be used via another interface (intended to be used when the first
interface is not available, for example). This, in turn, can lead to
spurious failures and timeouts simply because of the server address
order that resulted because of the enumeration process.
This patch makes the (safe?) assumption that there is no other better
rule to chose which interface's DNS server list should be prioritized.
After all, a DNS lookup isn't something "per network"; applications
don't look up "these DNS names on this interface and those DNS names on
that interface". There is a single resource pool of DNS servers and the
application should presume that any server will give it the "right"
answer. However, even if all DNS servers are assumed to give equally
useful responses, it is reasonable to expect that some DNS servers will
not accept requests on all interfaces. This patch avoids the problem by
sorting the DNS server addresses using the Windows IPv4/v6 routing tables.
For example, a request to DNS server C on interface 2 that is actually
sent over interface 1 (which may happen to have the default route) may
be rejected by or not delivered to DNS server C. So, better to use DNS
servers A and B associated with interface 1, at least as a first try.
By using the metric of the route to the DNS server itself as a proxy for
priority of the DNS server in the list, this patch is able to adapt
dynamically to changes in the interface list, the DNS server lists per
interface, which interfaces are active, the routing table, and so on,
while always picking a good "best" DNS server first.
In cases where any DNS server on any interface will do, this patch still
seems useful because it will prioritize a lower-metric route's (and thus
interface's) servers.
The current approach for disabling tests is not a good solution because
it forces you to pass --disable-tests, rather than auto-detect if your
system can support the tests in the first place. Many (most?) systems
do not have C++11. This also causes issues when chain-building c-ares,
the hosting system needs to be updated to support passing this
additional flag if necessary, it doesn't seem reasonable to add this
requirement which breaks compatibility.
This change auto-detects if the system can build the tests and
automatically disable them if it cannot. If you pass --enable-tests to
configure and the system cannot build them either due to lack of system
support, or because cross-compilation is being used, it will throw an
appropriate error since the user indicated they really did want the
tests.
Configure with:
./configure --enable-code-coverage
Show coverage output with:
make code-coverage-capture
Built on m4/ax_code_coverage.m4 from the GNU autoconf archive
to provide the macros to check for presence of gcov + lcov;
upstream macro modified to:
- Remove use of $(AM_DEFAULT_VERBOSITY) , as earlier versions of
autoconf (such as the one used by default on Travis) do not have this.
- Rather than automatically defining CODE_COVERAGE_RULES to be a set
of makefile rules that use ifeq/endif (which is GNU make-specific),
instead only define CODE_COVERAGE_RULES if coverages is turned on,
and in that case don't use conditionals in the makefile.
On iPhone targets like iOS, watchOS or tvOS the file
/etc/resolv.conf cannot be used to configure cares.
Instead the resolver library is queried for configuration
values.
CC: Yury Kirpichev <ykirpichev@yandex-team.ru>
Some basic checks we make were placed early enough in generated
configure script when using autoconf 2.5X versions. Newer autoconf
versions expand these checks much further into the configure script,
rendering them useless. Using XC_CONFIGURE_PREAMBLE fixes placement
of early intended checks across all our autoconf supported versions.
Tested with:
buildconf: autoconf version 2.69
buildconf: autom4te version 2.69
buildconf: autoheader version 2.69
buildconf: automake version 1.13.1
buildconf: aclocal version 1.13.1
buildconf: libtool version 2.4
buildconf: GNU m4 version 1.4.16
CARES_BUILDING_LIBRARY and CARES_STATICLIB no longer defined in ares_config.h,
configure will generate appropriate conditionals so that mentioned symbols
get defined and used in Makefile derived from Makefile.am at compilation time.
Recent versions of libtool are now tracing usage of AC_CONFIG_MACRO_DIR
macro and warn heavily when not used in configure script along with
ACLOCAL_AMFLAGS in Makefile.am. So in order to make libtool happy
while keeping backwards compatibility this is added.
Define HAVE_INET_NET_PTON only when system's inet_net_pton function is IPv6
capable and is not affected by the WLB-2008080064 advisory.
HAVE_INET_NET_PTON_IPV6 is no longer defined nor used.
07bc7ea7953392a50ea39912637d32
The purpose of the whole patch was to silence a compiler warning triggered
with GCC 4 on file ares_process.c The specific compiler warning was
'dereferencing type-punned pointer might break strict-aliasing rules'.
A simpler patch will follow to equally silence the warning.
AIX, at least, does not have sockaddr_storage.ss_family member.
Detect this in the configure logic and use proper #ifdefs in the
ares_process logic.
Signed-off-by: Ben Greear <greearb@candelatech.com>
Tested-by: Tor Arntsen <tor@spacetec.no>
This helps find compile warnings because they simply break
the build.
To use:
./configure --enable-warnings --enable-werror
Signed-off-by: Ben Greear <greearb@candelatech.com>
Brad House
Brad House
Thomas Köckerbauer
Chris Araman
Brad House
Daniel Stenberg
David Drysdale
Gregor Jasny
Yang Tse
Jakub Hrozek
Peter Pentchev
Ben Greear