Fix Socket(SafeSocketHandle) constructor on Apple platforms

[Copilot]

Description

On Apple platforms, GetSocketType cannot query SO_DOMAIN, returning AddressFamily.Unknown. This causes Socket(SafeSocketHandle) to skip _rightEndPoint initialization in its constructor switch, breaking Accept/AcceptAsync (they check _rightEndPoint == null).

Changes

Extract address family from getsockname buffer when _addressFamily is Unknown:

// Socket.cs constructor after getsockname succeeds
AddressFamily socketAddressFamily = _addressFamily;
if (socketAddressFamily == AddressFamily.Unknown && bufferLength >= 2)
{
    socketAddressFamily = SocketAddressPal.GetAddressFamily(buffer.Slice(0, bufferLength));
    _addressFamily = socketAddressFamily;
}
switch (socketAddressFamily) { ... }

Impact: Fixes tvOS test failures in Connect_Parallel_* tests. No effect on Linux/Windows where address family is already known.

Testing

• Manual testing
• Automated testing
• Took best possible action given testing or build constraints

Original prompt

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This section details on the original issue you should resolve

<issue_title>Assert.Equal failure in SocketAsyncEventArgsTest.Connect_Parallel_FailsOver (got 127.0.0.1:59851)</issue_title>
<issue_description>

Note: This issue was automatically generated by AI-Test-Triage. Please review and triage accordingly.

Build Information

Build: 20260129.1, 20260129.5

Build error leg or test failing: System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_FailsOver, System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Success, System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Fails

Affected CI jobs: build_tvOS_arm64_Release_AllSubsets_Mono

Causing Commit Range Information

Commit range: {TODO: Insert commit range or link to changes}

Summary

• Assert.Equal failure in SocketAsyncEventArgsTest.Connect_Parallel_FailsOver: Expected null, Actual 127.0.0.1:59851
• Job: build_tvOS_arm64_Release_AllSubsets_Mono; failing assembly: System.Net.Sockets.Tests
• Related test Connect_Parallel_Fails timed out with message 'Completed did not get called in time' (execution time ~30.00s)
• Connect_Parallel_Success also failed with System.InvalidOperationException: 'You must call the Bind method before performing this operation.' in Socket.AcceptAsync

Failure Statistics

Note: These statistics are based on the configured time range and might not reflect the full history of the failure.

• Occurrence Count: 8
• First Failure: 2026-01-29 13:02:39 UTC
• Last Failure: 2026-01-30 07:39:10 UTC

Work Items

Work Item	Console Log	Build	Job Name
System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_FailsOver	View Extract [06:40:47.3989140] 2026-01-29 03:40:47.535 System.Net.Sockets.Tests[7659:5589543] [FAIL] System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Fails [06:40:47.3990100] Completed did not get called in time [06:40:47.3990280] at System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Fails() ... [06:40:47.4664500] 2026-01-29 03:40:47.604 System.Net.Sockets.Tests[7659:5589620] [PASS] System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_FailsOver [06:40:47.4758460] 2026-01-29 03:40:47.613 System.Net.Sockets.Tests[7659:5589620] [FAIL] System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_FailsOver(preferIPv6: False) [06:40:47.4759200] Assert.Equal() Failure: Values differ [06:40:47.4759340] Expected: null [06:40:47.4759440] Actual: 127.0.0.1:59851 [06:40:47.4776640] at System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_FailsOver(Boolean preferIPv6) ... [06:48:15.2854480] Execution time: 10.1276581 [06:48:15.2854540] 2026-01-29 03:48:15.331 System.Net.Sockets.Tests[7659:5593880] 7) [FAIL] System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Fails Test name: System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Fails [06:48:15.2863300] Execution time: 30.0050317 [06:48:15.2863460] [FAIL] System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_FailsOver(preferIPv6: False) [06:48:15.2863550] Expected: null [06:48:15.2863640] Actual: 127.0.0.1:59851 ... [06:48:15.2872710] Exception messages: System.InvalidOperationException : You must call the Bind method before performing this operation. [06:48:15.2872710] Exception stack traces: at System.Net.Sockets.Socket.AcceptAsync(SocketAsyncEventArgs e, CancellationToken cancellationToken) Full Log	20260129.1	build_tvOS_arm64_Release_AllSubsets_Mono
System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Success	View Extract [06:48:30] dbug: [06:40:47.4981120] 2026-01-29 03:40:47.636 System.Net.Sockets.Tests[7659:5589620] [FAIL] System.Net.Sockets.Tests.SocketAsyncEventArgsTest.Connect_Parallel_Success [06:48:30] dbug: [06:40:47.4981440] System.InvalidOperationException : You must call the Bind method before performing this operation. [06:48:30] dbug: [06:40:47.4981610] 2026-01-29 03:40:47.636 System.Net.Sockets.Tests[7659:5589620] at System.Net.Sockets.Socket.AcceptAsync(SocketAsyncEventArgs e, CancellationToken cancellationToken) [06:48:30] dbug: [06:40:47.4981790] at Sys...

• Fixes Assert.Equal failure in SocketAsyncEventArgsTest.Connect_Parallel_FailsOver (got 127.0.0.1:59851) #123797

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[wfurt]

while the change itself seems reasonable, the failed test used TCP so this is unlikely root cause. Also it would be good to add more tests for the SO_DOMAIN. And the code is failing style cop checks as there are undesirable white spaces. Fix it @copilot and check for other reasons why we would get 'You must call the Bind method before performing this operation' for the test run. Perhaps look at some other tests that are passing on tvOS.