ts_tunnel: manage event lifecycle better, and recover from the stuck responder state - #390
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…etime Signed-off-by: David Anderson <danderson@tailscale.com> Change-Id: Icf2ccebcc78b533ac2534047c9a4c14d6a6a6964
Updated #339 Signed-off-by: David Anderson <danderson@tailscale.com> Change-Id: I86fd4c687bb92bab731c3460f63130c66a6a6964
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Two separate commits.
The first just replaces an uncancelable event with an event that gets canceled when the related session state is dropped, so we avoid some unnecessary timer callbacks.
The second cleans up half-completed handshakes in the responder role, where the initiator never confirms the session. Previously ts_tunnel just got stuck in that scenario, with the pending handshake unable to ever be cleared. With this change, it follows the behavior of the reference implementation and abandons the handshake when the unconfirmed session expires (i.e. couldn't be confirmed any more even if the initiator tried).
This allows a stuck responder to eventually recover, and potentially become the initiator later on if it wants to transmit.
Updates #339