Improve type safety for network protocol options

The existing implementation for NetworkProtocol.{Set}Option take
arguments of an empty interface type which all types (implicitly)
implement; any type may be passed to the functions.

This change introduces marker interfaces for network protocol options
that may be set or queried which network protocol option types implement
to ensure that invalid types are caught at compile time. Different
interfaces are used to allow the compiler to enforce read-only or
set-only socket options.

PiperOrigin-RevId: 328980359

1 files changed, 2 insertions, 2 deletions

diff --git a/pkg/tcpip/stack/nic_test.go b/pkg/tcpip/stack/nic_test.go
index 1e065b5c1..dd6474297 100644
--- a/pkg/tcpip/stack/nic_test.go
+++ b/pkg/tcpip/stack/nic_test.go
@@ -201,12 +201,12 @@ func (p *testIPv6Protocol) NewEndpoint(nicID tcpip.NICID, _ LinkAddressCache, _
 }
 
 // SetOption implements NetworkProtocol.SetOption.
-func (*testIPv6Protocol) SetOption(interface{}) *tcpip.Error {
+func (*testIPv6Protocol) SetOption(tcpip.SettableNetworkProtocolOption) *tcpip.Error {
 	return nil
 }
 
 // Option implements NetworkProtocol.Option.
-func (*testIPv6Protocol) Option(interface{}) *tcpip.Error {
+func (*testIPv6Protocol) Option(tcpip.GettableNetworkProtocolOption) *tcpip.Error {
 	return nil
 }