[netstack] Move SO_PASSCRED option to SocketOptions.

This change also makes the following fixes:
- Make SocketOptions use atomic operations instead of having to acquire/drop
  locks upon each get/set option.
- Make documentation more consistent.
- Remove tcpip.SocketOptions from socketOpsCommon because it already exists
  in transport.Endpoint.
- Refactors get/set socket options tests to be easily extendable.

PiperOrigin-RevId: 343103780

1 files changed, 3 insertions, 0 deletions

diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 173cd28ec..36b915510 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -1279,6 +1279,7 @@ func (e *endpoint) ModerateRecvBuf(copied int) {
 	e.rcvListMu.Unlock()
 }
 
+// SetOwner implements tcpip.Endpoint.SetOwner.
 func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
 	e.owner = owner
 }
@@ -1299,6 +1300,7 @@ func (e *endpoint) lastErrorLocked() *tcpip.Error {
 	return err
 }
 
+// LastError implements tcpip.Endpoint.LastError.
 func (e *endpoint) LastError() *tcpip.Error {
 	e.LockUser()
 	defer e.UnlockUser()
@@ -3213,6 +3215,7 @@ func (e *endpoint) Wait() {
 	}
 }
 
+// SocketOptions implements tcpip.Endpoint.SocketOptions.
 func (e *endpoint) SocketOptions() *tcpip.SocketOptions {
 	return &e.ops
 }