Improve MarkTest.

1. Add TCP SYN+ACK tests including syncookies and checks that
   accepting connections succeeids and that the sockets returned
   by accept() are marked.
2. Mark the tests more robust with respect to extra packets by
   always explicitly expecting packets (including when testing
   outgoing kernel-generated packets) and looking for them
   anywhere in the queue instead of insisting they're the first
   packet in the queue.
3. Make the tests more robust by using random source port,
   disabling ICMP rate limits, setting SO_REUSEADDR, and
   clearing queues more reliably.
4. Move from 2 to 4 interfaces (mostly made possible by the
   robustness improvements above).
5. Use named constants instead of repeating the numbers in
   multiple places.

Change-Id: I596e557a7eea02ccf603c812a9b8ea6f5b2f95da
3 files changed
tree: e253f9cd397717d94993a5d02137d406b0a2adab
  1. net/