Convey GSO capabilities through GSOEndpoint

...as all GSO capable endpoints must implement GSOEndpoint.

PiperOrigin-RevId: 371804175

3 files changed, 29 insertions, 12 deletions

diff --git a/pkg/tcpip/stack/forwarding_test.go b/pkg/tcpip/stack/forwarding_test.go
index 49c4a209c..7d3725681 100644
--- a/pkg/tcpip/stack/forwarding_test.go
+++ b/pkg/tcpip/stack/forwarding_test.go
@@ -264,6 +264,8 @@ type fwdTestPacketInfo struct {
 	Pkt               *PacketBuffer
 }
 
+var _ LinkEndpoint = (*fwdTestLinkEndpoint)(nil)
+
 type fwdTestLinkEndpoint struct {
 	dispatcher NetworkDispatcher
 	mtu        uint32
@@ -306,11 +308,6 @@ func (e fwdTestLinkEndpoint) Capabilities() LinkEndpointCapabilities {
 	return caps | CapabilityResolutionRequired
 }
 
-// GSOMaxSize returns the maximum GSO packet size.
-func (*fwdTestLinkEndpoint) GSOMaxSize() uint32 {
-	return 1 << 15
-}
-
 // MaxHeaderLength returns the maximum size of the link layer header. Given it
 // doesn't have a header, it just returns 0.
 func (*fwdTestLinkEndpoint) MaxHeaderLength() uint16 {
diff --git a/pkg/tcpip/stack/registration.go b/pkg/tcpip/stack/registration.go
index 7ad206f6d..e26225552 100644
--- a/pkg/tcpip/stack/registration.go
+++ b/pkg/tcpip/stack/registration.go
@@ -756,11 +756,6 @@ const (
 	CapabilitySaveRestore
 	CapabilityDisconnectOk
 	CapabilityLoopback
-	CapabilityHardwareGSO
-
-	// CapabilitySoftwareGSO indicates the link endpoint supports of sending
-	// multiple packets using a single call (LinkEndpoint.WritePackets).
-	CapabilitySoftwareGSO
 )
 
 // NetworkLinkEndpoint is a data-link layer that supports sending network
@@ -1047,10 +1042,29 @@ type GSO struct {
 	MaxSize uint32
 }
 
+// SupportedGSO returns the type of segmentation offloading supported.
+type SupportedGSO int
+
+const (
+	// GSONotSupported indicates that segmentation offloading is not supported.
+	GSONotSupported SupportedGSO = iota
+
+	// HWGSOSupported indicates that segmentation offloading may be performed by
+	// the hardware.
+	HWGSOSupported
+
+	// SWGSOSupported indicates that segmentation offloading may be performed in
+	// software.
+	SWGSOSupported
+)
+
 // GSOEndpoint provides access to GSO properties.
 type GSOEndpoint interface {
 	// GSOMaxSize returns the maximum GSO packet size.
 	GSOMaxSize() uint32
+
+	// SupportedGSO returns the supported segmentation offloading.
+	SupportedGSO() SupportedGSO
 }
 
 // SoftwareGSOMaxSize is a maximum allowed size of a software GSO segment.
diff --git a/pkg/tcpip/stack/route.go b/pkg/tcpip/stack/route.go
index 4ecde5995..8a044c073 100644
--- a/pkg/tcpip/stack/route.go
+++ b/pkg/tcpip/stack/route.go
@@ -300,12 +300,18 @@ func (r *Route) RequiresTXTransportChecksum() bool {
 
 // HasSoftwareGSOCapability returns true if the route supports software GSO.
 func (r *Route) HasSoftwareGSOCapability() bool {
-	return r.outgoingNIC.LinkEndpoint.Capabilities()&CapabilitySoftwareGSO != 0
+	if gso, ok := r.outgoingNIC.LinkEndpoint.(GSOEndpoint); ok {
+		return gso.SupportedGSO() == SWGSOSupported
+	}
+	return false
 }
 
 // HasHardwareGSOCapability returns true if the route supports hardware GSO.
 func (r *Route) HasHardwareGSOCapability() bool {
-	return r.outgoingNIC.LinkEndpoint.Capabilities()&CapabilityHardwareGSO != 0
+	if gso, ok := r.outgoingNIC.LinkEndpoint.(GSOEndpoint); ok {
+		return gso.SupportedGSO() == HWGSOSupported
+	}
+	return false
 }
 
 // HasSaveRestoreCapability returns true if the route supports save/restore.