diff options
| author | Sepehr Raissian <sepehrtheraiss@gmail.com> | 2018-09-28 10:59:21 -0700 |
|---|---|---|
| committer | Shentubot <shentubot@google.com> | 2018-09-28 11:00:16 -0700 |
| commit | c17ea8c6e20f58510b063f064d45608792a014e4 (patch) | |
| tree | 272920bd1036a776e3e7c852c2c5795dc4f2a805 /pkg/tcpip/stack/registration.go | |
| parent | cf226d48ce8c49409049e03ed405366db9fc2a04 (diff) | |
Block for link address resolution
Previously, if address resolution for UDP or Ping sockets required sending
packets using Write in Transport layer, Resolve would return ErrWouldBlock
and Write would return ErrNoLinkAddress. Meanwhile startAddressResolution
would run in background. Further calls to Write using same address would also
return ErrNoLinkAddress until resolution has been completed successfully.
Since Write is not allowed to block and System Calls need to be
interruptible in System Call layer, the caller to Write is responsible for
blocking upon return of ErrWouldBlock.
Now, when startAddressResolution is called a notification channel for
the completion of the address resolution is returned.
The channel will traverse up to the calling function of Write as well as
ErrNoLinkAddress. Once address resolution is complete (success or not) the
channel is closed. The caller would call Write again to send packets and
check if address resolution was compeleted successfully or not.
Fixes google/gvisor#5
Change-Id: Idafaf31982bee1915ca084da39ae7bd468cebd93
PiperOrigin-RevId: 214962200
Diffstat (limited to 'pkg/tcpip/stack/registration.go')
| -rw-r--r-- | pkg/tcpip/stack/registration.go | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/pkg/tcpip/stack/registration.go b/pkg/tcpip/stack/registration.go index 595c7e793..0acec2984 100644 --- a/pkg/tcpip/stack/registration.go +++ b/pkg/tcpip/stack/registration.go @@ -289,7 +289,11 @@ type LinkAddressCache interface { // registered with the network protocol, the cache attempts to resolve the address // and returns ErrWouldBlock. Waker is notified when address resolution is // complete (success or not). - GetLinkAddress(nicid tcpip.NICID, addr, localAddr tcpip.Address, protocol tcpip.NetworkProtocolNumber, w *sleep.Waker) (tcpip.LinkAddress, *tcpip.Error) + // + // If address resolution is required, ErrNoLinkAddress and a notification channel is + // returned for the top level caller to block. Channel is closed once address resolution + // is complete (success or not). + GetLinkAddress(nicid tcpip.NICID, addr, localAddr tcpip.Address, protocol tcpip.NetworkProtocolNumber, w *sleep.Waker) (tcpip.LinkAddress, <-chan struct{}, *tcpip.Error) // RemoveWaker removes a waker that has been added in GetLinkAddress(). RemoveWaker(nicid tcpip.NICID, addr tcpip.Address, waker *sleep.Waker) |