Work in Progress - Incomplete Request

[thomas-mangin]

…arios

This commit implements extensive test coverage for race conditions that can occur during concurrent BGP connection operations:

Test Coverage:

1. Simultaneous Bi-directional Connections

   • Test collision detection when both peers connect simultaneously
   • Test file descriptor reuse race conditions
   • Test concurrent incoming/outgoing connection establishment

2. Connection Reset During I/O Operations

   • Test graceful handling of connection resets during message transmission
   • Test connection resets during message reception
   • Test explicit close() during active I/O operations

3. Rapid Connect/Disconnect Cycles

   • Test for file descriptor leaks under rapid cycling
   • Test proper cleanup of polling state
   • Test handling of partial I/O operations during disconnection

4. Polling State Race Conditions

   • Test concurrent reading() and writing() calls
   • Test poller cleanup after socket errors
   • Test timeout handling in polling operations

5. Message Queue Ordering

   • Test message ordering during concurrent read/write
   • Test BGP message assembly with fragmented arrivals
   • Test buffer state consistency during partial reads

6. Connection State Transitions

   • Test close() during connection establishment
   • Test idempotent behavior of multiple close() calls
   • Test I/O operation rejection after close()

All 18 tests verify proper synchronization, error handling, and resource cleanup in timing-sensitive scenarios. These tests help ensure ExaBGP's connection handling remains robust under concurrent load conditions.