[DONTMERGE] Test run with reproducer for forced chunked recv #36751

WARNING: NOT INTENDED FOR MERGING!

Performing a test run with forced chunked recv.

All networking code using sockets must not make assumption about the chunking of the incoming/outgoing data, and should be resilient against any chunking. Normally, the chunking of the sends of the writer dictate the chunking of the receives at the reader, but this is not guaranteed by IP/TCP, intermediate networking elements may change the packet structure.

This branch contains a stress test reproducer. For every socket read, recv() is not called to read all available data, but data is read and returned in smaller chunks. The goal is to test code for robustness in face of unexpected chunking of the data.

This PR will be closed once the test runs complete, and kept for reference (some tests are expected to fail).

Similar to #36724 .

WARNING: NOT INTENDED FOR MERGING!

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External sites

• Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36751
• Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36751.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36751#author-ralph

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🚧 At least one of the CI tasks failed. _{Task macOS native: https://github.com/bitcoin/bitcoin/actions/runs/41794882715/job/126456522377} _{LLM reason (✨ experimental): CI failed because the sock_tests CTest test failed.}

<details><summary>Hints</summary>

Try to run the tests locally, according to the documentation. However, a CI failure may still happen due to a number of reasons, for example:

• Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

• A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.

• An intermittent issue.

Leave a comment here, if you need help tracking down a confusing failure.

</details>

A socket unit test failed (sock_tests/send_and_receive), so integration tests were not executed. Including a commit with a fix for the unit test, for a 2nd run.

test/sock_tests.cpp(132): error: in "sock_tests/send_and_receive": check receiver.Recv(recv_buf, sizeof(recv_buf), 0) == msg_len has failed [1 != 4]
test/sock_tests.cpp(133): error: in "sock_tests/send_and_receive": check strncmp(msg, recv_buf, msg_len) == 0 has failed [1 != 0]
test/sock_tests.cpp(132): error: in "sock_tests/send_and_receive": check receiver.Recv(recv_buf, sizeof(recv_buf), 0) == msg_len has failed [1 != 4]
test/sock_tests.cpp(133): error: in "sock_tests/send_and_receive": check strncmp(msg, recv_buf, msg_len) == 0 has failed [-1 != 0]

CI runs timed out, in some cases a log line is created for every read, and the many small chunks slowed down runs considerably. In local runs this didn't cause a problem. I've changed the reproducer to break up less aggressively: for large streams always read the third of the available data at once. I hope this will make a difference.

CI runs have completed, with some failures (as expected).

Added failed cases to #36726 -- sock_tests/send_and_receive unit test, interface_http.py,feature_torcontrol.py.

Closing this PR (it was not intended for merging, keeping it for reference).