Fix debian symbol not found for test_HttpTransact

[lzx404243]

As reported in #9601, running the unit test test_HttpTransact result in the "symbol not found" error on Debian when ATS is configured with the enable-hardening flag.

This PR adds a bunch of stubs to resolve these errors. Suggestions on any cleaner way to resolve this is also welcome :)

This resolves #9601.

[lzx404243]

The docker container I am doing the testing in is based off the ci.trafficserver.apache.org/ats/debian:11 image.

[cmcfarlen]

It seems like this chunk from proxy/http/Makefile.am is what allows test_HttpTransact to even link in the first place:

if OS_LINUX
test_HttpTransact_LDFLAGS = $(AM_LDFLAGS)\
   -Wl,--unresolved-symbols=ignore-all
else
test_HttpTransact_LDFLAGS = $(AM_LDFLAGS)\
    -Wl,-undefined -Wl,suppress -Wl,-flat_namespace -Wl,-dead_strip
endif

If the hardening linker flags are specified then the symbols missing are needed for whatever security stuff happens before the code is executed or perhaps it's a problem because lazy binding is disabled. Either way these two linker flags seem to be at odds. There is a similar situation in the http3 directory as well, but these are the only two places that I found that use this flag.

As for what to do, I recommend we remove this ignore-all and link the appropriate stubs and/or libraries that are needed to link normally. This is a pain to do, so I could see the case for just merging this as is and accept that it will require maintenance from time to time. At the very least I would add a lot more commentary on why we need to stub these out, specifically mentioning the hardening configuration.

[maskit]

I'm the guy who added the ignore-all flag. I tried to link dependent objects in a normal way, but it was too painful and ended up adding the flag. I'm fine with removing the flag if we can run the tests, but we should probably make CI green first, and have the hardening flag one of the GitHub CI jobs so we won't be surprised after merging PRs.

[bneradt]

and have the hardening flag one of the GitHub CI jobs so we won't be surprised after merging PRs.

+1. Once we do whatever fix we agree to with addressing this, I'll configure the debian PR CI to run with --enable-hardening

[cmcfarlen]

Using the LDADD flags from the traffic_server makefile does work to link this test. Could use that, or start with that and try to prune some back.

[maskit]

Using the LDADD flags from the traffic_server makefile does work to link this test.

Well, linking everything would work for all tests for sure, but I don't want to lose the hints (objects we currently link and the stubs) we gathered so far.

@lzx404243 Can we remove the ignore-all flag if we have these stubs? Or does it still does some work?

[lzx404243]

@maskit After removing the ignore-all flag, there would be some compile-time errors such as the following:

/usr/bin/ld: ../../iocore/eventsystem/libinkevent.a(UnixEventProcessor.o): undefined reference to symbol 'hwloc_bitmap_snprintf'
/usr/bin/ld: /usr/lib/x86_64-linux-gnu/libhwloc.so.15: error adding symbols: DSO missing from command line

[maskit]

@lzx404243 Thanks for checking it.

I'd take this as it is, but leave the decision to @cmcfarlen .

[lzx404243]

@cmcfarlen Thanks for your input. I removed the stubs and the ignore-all flag, and now linking with the libs from traffic_server LDADD (with some pruning). Let me know if you have any further comments or suggestions.

[cmcfarlen]

Awesome, thanks!

[zwoop]

@bneradt This has merge conflicts on 9.2.x, can you please make a 9.2.x branch PR please?