The DNS configuration for apple is stored in the system configuration
database. Apple does provide an emulated `/etc/resolv.conf` on MacOS
(but not iOS), it cannot, however, represent the entirety of the DNS
configuration. Alternatively, libresolv could be used to also retrieve
some system configuration, but it too is not capable of retrieving the
entirety of the DNS configuration.
Attempts to use the preferred public API of `SCDynamicStoreCreate()` and
friends yielded incomplete DNS information. Instead, that leaves some
apple "internal" symbols from `configd` that we need to access in order
to get the entire configuration. We can see that we're not the only ones
to do this as Google Chrome also does:
https://chromium.googlesource.com/chromium/src/+/HEAD/net/dns/dns_config_watcher_mac.cc
These internal functions are what what`libresolv` and `scutil` use to
retrieve the dns configuration. Since these symbols are not publicly
available, we will dynamically load the symbols from `libSystem` and
import the `dnsinfo.h` private header extracted from:
https://opensource.apple.com/source/configd/configd-1109.140.1/dnsinfo/dnsinfo.h
Fix By: Brad House (@bradh352)
CMake was unconditionally setting output locations globally, but
it should not do that if it is not the top-level project (e.g.
during chain building). Detect this fact and only set the output
location when top level.
Fixes Issue: #708
Fix By: Anthony Alayo (@anthonyalayo)
This PR implements an event thread to process all events on file descriptors registered by c-ares. Prior to this feature, integrators were required to understand the internals of c-ares and how to monitor file descriptors and timeouts and process events.
Implements OS-specific efficient polling such as epoll(), kqueue(), or IOCP, and falls back to poll() or select() if otherwise unsupported. At this point, it depends on basic threading primitives such as pthreads or windows threads.
If enabled via the ARES_OPT_EVENT_THREAD option passed to ares_init_options(), then socket callbacks cannot be used.
Fixes Bug: #611
Fix By: Brad House (@bradh352)
External integrations don't need sys/random.h in order to compile, remove the dependency. Try to fix building on legacy MacOS versions.
Fixes Issue: #682
Fix By: Brad House (@bradh352)
* cmake: avoid warning about non-existing include dir
In the Debian build logs I noticed the following warning:
cc1: warning: /build/c-ares-1.25.0/test/include: No such file or directory [-Wmissing-include-dirs]
This happened because ${CMAKE_INSTALL_INCLUDEDIR} had been added to
caresinternal. I believe it has been copied from the "real" lib
where it's used in the INSTALL_INTERFACE context. But because
caresinternal is never installed we don't need that include here.
* cmake: drop CARES_TOPLEVEL_DIR variable
The CARES_TOPLEVEL_DIR variable is the same as the automatically
created PROJECT_SOURCE_DIR variable. Let's stick to the official
one. Also because it is already used at places where CARES_TOPLEVEL_DIR
is used as well.
Fix By: Gregor Jasny (@gjasny)
Completely rework the autotools build system, issues have cropped up due to the complexity and could cause issues on even semi-modern Linux systems (Ubuntu 20.04 for example).
Changes include:
Remove all curl/xc/cares m4 helper files, they go overboard on detections of functions and datatypes. Go back to more plain autoconf macros as they've come a long way over the years.
Use known systems and heuristics to determine datatypes for functions like send() and recv(), rather than the error prone detection which required thousands of permutations and might still get it wrong.
Remove unneeded configure arguments like --enable-debug or --enable-optimize, its more common for people to simply pass their own CFLAGS on the command line.
Only require CARES_STATICLIB definition on Windows static builds, its not necessary ever for other systems, even when hiding non-public symbols.
Remove some function and definition detections that were never used in c-ares
The test framework is now embedded into the toplevel configure system, there was no need to chain build the test system as it is never built externally to c-ares.
As a side-effect of the changes, a configure run completes in about 25% of the original time.
This has been tested on various Linux distributions (of varying age), FreeBSD, MacOS, Windows (via MSYS2 with Mingw), and Solaris10/11 (by @dfandrich), AIX 7.3 (by @dfandrich). It is not unlikely that this may have broken more esoteric or legacy systems, and we'll likely need to be ready to accept bug reports and patches, but it has removed over 10k lines of build system code. It is very likely any issues that crop up will add far fewer lines of code to fix such systems.
Fixes Bug: #670
Fix By: Brad House (@bradh352)
Old MacOS SDKs (like 10.8) require you include `sys/socket.h` before you include `net/if.h` as reported by MacPorts. Using a new SDK but with setting the macos target version does not have the same issue.
Fixes Issue: #672
Fix By: Brad House (@bradh352)
There is a reported build issue where getrandom() is detected
but compile fails due to a missing prototype. This commit attempts
to resolve that issue.
Fixes Bug: #665
Fix By: Brad House (@bradh352)
GoogleTest should be unbundled. Google changed their guidance a few years back and modern versions of google test cannot build the bundling code file.
This PR also updates to use C++14 as is required by modern GoogleTest versions.
Fixes Bug: #506
Fix By: Brad House (@bradh352)
Some environments may send router advertisements on a link setting their link-local (fe80::/10) address as a valid DNS server to the remote system. This will cause a DNS entry to be created like `fe80::1%iface`, since all link-local network interfaces are technically part of the same /10 subnet, it must be told what interface to send packets through explicitly if there are multiple physical interfaces.
This PR adds support for the %iface modifier when setting DNS servers via `/etc/resolv.conf` as well as via `ares_set_servers_csv()`.
For MacOS and iOS it is assumed that libresolve will set the `sin6_scope_id` and should be supported, but my test systems don't seem to read the Router Advertisement for RDNSS link-local. Specifying the link-local dns server on MacOS via adig has been tested and confirmed working.
For Windows, this is similar to MacOS in that the system doesn't seem to honor the RDNSS RA, but specifying manually has been tested to work.
At this point, Android support does not exist.
Fixes Bug #462
Supersedes PR #463
Fix By: Brad House (@bradh352) and Serhii Purik (@sergvpurik)
c-ares does not have any concept of thread-safety. It has always been 100% up to the implementor to ensure they never call c-ares from more than one thread at a time. This patch adds basic thread-safety support, which can be disabled at compile time if not desired. It uses a single recursive mutex per channel, which should be extremely quick when uncontested so overhead should be minimal.
Fixes Bug: #610
Also sets the stage to implement #611
Fix By: Brad House (@bradh352)
When building for UWP (WindowsStore), additional headers are needed and some functions are not available. This also adds AppVeyor CI/CD support to catch these issues in the future.
Fix By: Deal (@halx99) and Brad House (@bradh352)
AppVeyor was using Visual Studio 2015 along with old versions of MinGW. Update to the latest AppVeyor provides and also add an MSYS2 build test using MinGW which will use the bleeding edge version.
When researching #590 this also uncovered a bug in cmake not properly detecting if_indextoname() on windows. This has been corrected as well as the underlying issue reported in #590.
Fix By: Brad House (@bradh352) and Jonas Kvinge (@jonaski)
HOSTS FILE PROCESSING OVERVIEW
==============================
The hosts file on the system contains static entries to be processed locally
rather than querying the nameserver. Each row is an IP address followed by
a list of space delimited hostnames that match the ip address. This is used
for both forward and reverse lookups.
We are caching the entire parsed hosts file for performance reasons. Some
files may be quite sizable and as per Issue #458 can approach 1/2MB in size,
and the parse overhead on a rapid succession of queries can be quite large.
The entries are stored in forwards and backwards hashtables so we can get
O(1) performance on lookup. The file is cached until the file modification
timestamp changes (or 60s if there is no implemented stat() capability).
The hosts file processing is quite unique. It has to merge all related hosts
and ips into a single entry due to file formatting requirements. For
instance take the below:
```
127.0.0.1 localhost.localdomain localhost
::1 localhost.localdomain localhost
192.168.1.1 host.example.com host
192.168.1.5 host.example.com host
2620🔢:1 host.example.com host6.example.com host6 host
```
This will yield 2 entries.
1) ips: `127.0.0.1,::1`
hosts: `localhost.localdomain,localhost`
2) ips: `192.168.1.1,192.168.1.5,2620🔢:1`
hosts: `host.example.com,host,host6.example.com,host6`
It could be argued that if searching for `192.168.1.1` that the `host6`
hostnames should not be returned, but this implementation will return them
since they are related (both ips have the fqdn of host.example.com). It is
unlikely this will matter in the real world.
Fix By: Brad House (@bradh352)
PR #568 increased the warning levels and c-ares code emitted a bunch of warnings. This PR fixes those warnings and starts transitioning internal data types into more proper forms (e.g. data lengths should be size_t not int). It does, however, have to manually cast back to what the public API needs due to API and ABI compliance (we aren't looking to break integrations, just clean up internals).
Fix By: Brad House (@bradh352)
c-ares was missing a couple of common compiler warnings during building that are widely recognized as a best practice. This PR makes no code changes, only build system changes to increase warning levels.
This PR does cause some new warnings to be emitted, a follow-up PR will address those.
Fix By: Brad House (@bradh352)
All files have their licence and copyright information clearly
identifiable. If not in the file header, they are set separately in
.reuse/dep5.
All used license texts are provided in LICENSES/
* segment random number generation into own file
* abstract random code to make it more modular so we can have multiple backends
* rand: add support for arc4random_buf() and also direct CARES_RANDOM_FILE reading
* autotools: fix detection of arc4random_buf
* rework initial rc4 seed for PRNG as last fallback
* rc4: more proper implementation, simplified for clarity
* clarifications
* CARES_RANDOM_FILE should always default to /dev/urandom
During cross-compilation, CARES_RANDOM_FILE may not be able to be appropriately
detected, therefore we should always set it to /dev/urandom and allow the
entity requesting compilation override the value. The code does appropriately
fall back if CARES_RANDOM_FILE cannot be opened.
* use set not option
When determining value for CPACK_PACKAGE_ARCHITECTURE, prefer to use
value from CMAKE_SYSTEM_PROCESSOR before falling back to uname output.
Additionally, if building from a Windows host, emit a fatal error
instead of attempting to call uname.
Fix By: Bobby Reynolds (@reynoldsbd)
As per RFC6761 Section 6.3, "localhost" lookups need to be special cased to return loopback addresses, and not forward queries to recursive dns servers.
We first look up via files (/etc/hosts or equivalent), and if that fails, we then attempt a system-specific address enumeration for loopback addresses (currently Windows-only), and finally fallback to ::1 and 127.0.0.1.
Fix By: Brad House (@bradh352)
Fixes Bug: #399
Brad House
Chenyu Yang
Faraz
Gregor Jasny
Christian Clauss
Daniel Stenberg
Ben Noordhuis
Bobby Reynolds
Jérôme Duval