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)
The rc4 function iterates over a buffer of size buffer_len who's maximum
value is INT_MAX with a counter of type short that is not guaranteed to
have maximum size INT_MAX.
In circumstances where short is narrower than int and where buffer_len
is larger than the maximum value of a short, it may be possible to loop
infinitely as counter will overflow and never be greater than or equal
to buffer_len.
The solution is to make the comparison be between types of equal width.
This commit defines counter as an int.
Fix By: Fionn Fitzmaurice (@fionn)
Brad House
Jay Freeman (saurik)
Fionn Fitzmaurice