Fix a race in reading last seen ICMP error during handshake

On receiving an ICMP error during handshake, the error is propagated
by reading `endpoint.lastError`. This can race with the socket layer
invoking getsockopt() with SO_ERROR where the same value is read and
cleared, causing the handshake to bail out with a non-error state.

Fix the race by checking for lastError state and failing the
handshake with ErrConnectionAborted if the lastError was read and
cleared by say SO_ERROR.

The race mentioned in the bug, is caught only with the newly added
tcp_test unit test, where we have control over stopping/resuming
protocol loop. Adding a packetimpact test as well for sanity testing
of ICMP error handling during handshake.

Fixes #5922

PiperOrigin-RevId: 372135662

0 files changed, 0 insertions, 0 deletions