Pure-Python implementation of socket.socketpair() doesn't authenticate connected socket

[sethmlarson]

Bug report

Bug description:

socket.socketpair() has a fall-back implementation on platforms that don't support socket.AF_UNIX which uses AF_INET[6] sockets bound to localhost. This connection is expected to come from the same process.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux, Windows

Linked PRs

• gh-122133: Authenticate socket connection for socket.socketpair() fallback #122134
• [3.13] gh-122133: Authenticate socket connection for socket.socketpair() fallback (GH-122134) #122424
• [3.12] gh-122133: Authenticate socket connection for socket.socketpair() fallback (GH-122134) #122425
• [3.11] gh-122133: Authenticate socket connection for socket.socketpair() fallback (GH-122134) #122426
• [3.10] gh-122133: Authenticate socket connection for socket.socketpair() fallback (GH-122134) #122427
• [3.9] gh-122133: Authenticate socket connection for socket.socketpair() fallback (GH-122134) #122428
• [3.8] gh-122133: Authenticate socket connection for socket.socketpair() fallback (GH-122134) #122429
• gh-122133: Rework pure Python socketpair tests to avoid use of importlib.reload. #122493
• [3.13] gh-122133: Rework pure Python socketpair tests to avoid use of importlib.reload. (GH-122493) #122504
• [3.12] gh-122133: Rework pure Python socketpair tests to avoid use of importlib.reload. (GH-122493) #122505
• [3.11] gh-122133: Rework pure Python socketpair tests to avoid use of importlib.reload. (GH-122493) #122506
• [3.10] gh-122133: Rework pure Python socketpair tests to avoid use of importlib.reload. (GH-122493) #122507
• [3.9] gh-122133: Rework pure Python socketpair tests to avoid use of importlib.reload. (GH-122493) #122508
• [3.8] gh-122133: Rework pure Python socketpair tests to avoid use of importlib.reload. (GH-122493) #122509