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/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index 95dc8ed57..81093e9ca 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -297,9 +297,9 @@ func (ep *endpoint) Readiness(mask waiter.EventMask) waiter.EventMask {
 // SetSockOpt implements tcpip.Endpoint.SetSockOpt. Packet sockets cannot be
 // used with SetSockOpt, and this function always returns
 // tcpip.ErrNotSupported.
-func (ep *endpoint) SetSockOpt(opt interface{}) *tcpip.Error {
+func (ep *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 	switch opt.(type) {
-	case tcpip.SocketDetachFilterOption:
+	case *tcpip.SocketDetachFilterOption:
 		return nil
 
 	default:
@@ -366,7 +366,7 @@ func (ep *endpoint) LastError() *tcpip.Error {
 }
 
 // GetSockOpt implements tcpip.Endpoint.GetSockOpt.
-func (*endpoint) GetSockOpt(interface{}) *tcpip.Error {
+func (*endpoint) GetSockOpt(tcpip.GettableSocketOption) *tcpip.Error {
 	return tcpip.ErrNotSupported
 }