Improve type safety for socket options

The existing implementation for {G,S}etSockOpt 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 socket options that may be
set or queried which socket 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.

Fixes #3714.

RELNOTES: n/a
PiperOrigin-RevId: 328832161

1 files changed, 3 insertions, 3 deletions

diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index 2087bcfa8..71feeb748 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -510,9 +510,9 @@ func (e *endpoint) Readiness(mask waiter.EventMask) waiter.EventMask {
 }
 
 // SetSockOpt implements tcpip.Endpoint.SetSockOpt.
-func (e *endpoint) SetSockOpt(opt interface{}) *tcpip.Error {
+func (e *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 	switch opt.(type) {
-	case tcpip.SocketDetachFilterOption:
+	case *tcpip.SocketDetachFilterOption:
 		return nil
 
 	default:
@@ -577,7 +577,7 @@ func (e *endpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) *tcpip.Error {
 }
 
 // GetSockOpt implements tcpip.Endpoint.GetSockOpt.
-func (*endpoint) GetSockOpt(interface{}) *tcpip.Error {
+func (*endpoint) GetSockOpt(tcpip.GettableSocketOption) *tcpip.Error {
 	return tcpip.ErrUnknownProtocolOption
 }