TUN fixes

Hello,

While looking through the latest commits I noticed that 996c7c4 ("Removed IFF_NO_PI from TUN linux", 2017-12-04) broke the test suite and darwin and windows builds by changing the TUNDevice interface. This patch series adds documentation and tries to fix the tests and the darwin/windows tun (however that part is untested as I don't have access to these systems and it looks like the build is already broken for a while).

Note that d73f960 ("Peer timer teardown", 2017-12-29) broke the tests in a separate way so even with these patches the test suite will not pass.

Regards
Simon

Simon Ruderich (7):
tun: TUNDevice: document behavior of offset parameter
tun_linux: add PIHeaderSize constant instead of magic value
tun_linux: document packet information header values
helper_test: reorder DummyTUN functions to follow interface order
helper_test: adapt to TUNDevice interface change
tun_darwin: adapt to TUNDevice interface change
tun_darwin: adapt to TUNDevice interface change

 src/helper_test.go | 26 +++++++++++++-------------
 src/tun.go         |  4 ++--
 src/tun_darwin.go  | 13 ++++++++++---
 src/tun_linux.go   | 11 +++++++----
 src/tun_windows.go |  8 ++++++--
 5 files changed, 38 insertions(+), 24 deletions(-)

2.15.1