Support getsockopt for SO_ACCEPTCONN.

The SO_ACCEPTCONN option is used only on getsockopt(). When this option is
specified, getsockopt() indicates whether socket listening is enabled for
the socket. A value of zero indicates that socket listening is disabled;
non-zero that it is enabled.

PiperOrigin-RevId: 338703206

6 files changed, 21 insertions, 3 deletions

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index d77848d61..a7d54d3b9 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -763,6 +763,10 @@ const (
 	// endpoint that all packets being written have an IP header and the
 	// endpoint should not attach an IP header.
 	IPHdrIncludedOption
+
+	// AcceptConnOption is used by GetSockOptBool to indicate if the
+	// socket is a listening socket.
+	AcceptConnOption
 )
 
 // SockOptInt represents socket options which values have the int type.
diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index 41eb0ca44..a17234946 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -378,7 +378,7 @@ func (e *endpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) *tcpip.Error {
 // GetSockOptBool implements tcpip.Endpoint.GetSockOptBool.
 func (e *endpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error) {
 	switch opt {
-	case tcpip.KeepaliveEnabledOption:
+	case tcpip.KeepaliveEnabledOption, tcpip.AcceptConnOption:
 		return false, nil
 
 	default:
diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index 072601d2d..31831a6d8 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -389,7 +389,12 @@ func (ep *endpoint) GetSockOpt(opt tcpip.GettableSocketOption) *tcpip.Error {
 
 // GetSockOptBool implements tcpip.Endpoint.GetSockOptBool.
 func (*endpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error) {
-	return false, tcpip.ErrNotSupported
+	switch opt {
+	case tcpip.AcceptConnOption:
+		return false, nil
+	default:
+		return false, tcpip.ErrNotSupported
+	}
 }
 
 // GetSockOptInt implements tcpip.Endpoint.GetSockOptInt.
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index e37c00523..79f688129 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -601,7 +601,7 @@ func (e *endpoint) GetSockOpt(opt tcpip.GettableSocketOption) *tcpip.Error {
 // GetSockOptBool implements tcpip.Endpoint.GetSockOptBool.
 func (e *endpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error) {
 	switch opt {
-	case tcpip.KeepaliveEnabledOption:
+	case tcpip.KeepaliveEnabledOption, tcpip.AcceptConnOption:
 		return false, nil
 
 	case tcpip.IPHdrIncludedOption:
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 3bcd3923a..c826942e9 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -1999,6 +1999,12 @@ func (e *endpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error) {
 	case tcpip.MulticastLoopOption:
 		return true, nil
 
+	case tcpip.AcceptConnOption:
+		e.LockUser()
+		defer e.UnlockUser()
+
+		return e.EndpointState() == StateListen, nil
+
 	default:
 		return false, tcpip.ErrUnknownProtocolOption
 	}
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index d57ed5d79..d31177eb7 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -895,6 +895,9 @@ func (e *endpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error) {
 
 		return v, nil
 
+	case tcpip.AcceptConnOption:
+		return false, nil
+
 	default:
 		return false, tcpip.ErrUnknownProtocolOption
 	}