This commit adds a batchingConn interface, and renames batchingUDPConn
to linuxBatchingConn. tryUpgradeToBatchingConn() may return a platform-
specific implementation of batchingConn. So far only a Linux
implementation of this interface exists, but this refactor is being
done in anticipation of a Windows implementation.
Updates tailscale/corp#21874
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Add an enable/disable argument to setDontFragment() in preparation for dynamic
enable/disable of peer path MTU discovery. Add getDontFragment() to get the
status of the don't fragment bit from a socket.
Updates #311
Co-authored-by: James Tucker <james@tailscale.com>
Signed-off-by: Val <valerie@tailscale.com>