Add TCP checksum verification.

PiperOrigin-RevId: 242704699
Change-Id: I87db368ca343b3b4bf4f969b17d3aa4ce2f8bd4f

4 files changed, 16 insertions, 10 deletions

diff --git a/pkg/tcpip/link/fdbased/endpoint.go b/pkg/tcpip/link/fdbased/endpoint.go
index 20e34c5ee..84439a9ed 100644
--- a/pkg/tcpip/link/fdbased/endpoint.go
+++ b/pkg/tcpip/link/fdbased/endpoint.go
@@ -122,13 +122,14 @@ type Options struct {
 	FD                 int
 	MTU                uint32
 	EthernetHeader     bool
-	ChecksumOffload    bool
 	ClosedFunc         func(*tcpip.Error)
 	Address            tcpip.LinkAddress
 	SaveRestore        bool
 	DisconnectOk       bool
 	GSOMaxSize         uint32
 	PacketDispatchMode PacketDispatchMode
+	TXChecksumOffload  bool
+	RXChecksumOffload  bool
 }
 
 // New creates a new fd-based endpoint.
@@ -142,8 +143,12 @@ func New(opts *Options) tcpip.LinkEndpointID {
 	}
 
 	caps := stack.LinkEndpointCapabilities(0)
-	if opts.ChecksumOffload {
-		caps |= stack.CapabilityChecksumOffload
+	if opts.RXChecksumOffload {
+		caps |= stack.CapabilityRXChecksumOffload
+	}
+
+	if opts.TXChecksumOffload {
+		caps |= stack.CapabilityTXChecksumOffload
 	}
 
 	hdrSize := 0
@@ -527,12 +532,13 @@ func (e *InjectableEndpoint) Inject(protocol tcpip.NetworkProtocolNumber, vv buf
 }
 
 // NewInjectable creates a new fd-based InjectableEndpoint.
-func NewInjectable(fd int, mtu uint32) (tcpip.LinkEndpointID, *InjectableEndpoint) {
+func NewInjectable(fd int, mtu uint32, capabilities stack.LinkEndpointCapabilities) (tcpip.LinkEndpointID, *InjectableEndpoint) {
 	syscall.SetNonblock(fd, true)
 
 	e := &InjectableEndpoint{endpoint: endpoint{
-		fd:  fd,
-		mtu: mtu,
+		fd:   fd,
+		mtu:  mtu,
+		caps: capabilities,
 	}}
 
 	return stack.RegisterLinkEndpoint(e), e
diff --git a/pkg/tcpip/link/loopback/loopback.go b/pkg/tcpip/link/loopback/loopback.go
index d58c0f885..2dc4bcfda 100644
--- a/pkg/tcpip/link/loopback/loopback.go
+++ b/pkg/tcpip/link/loopback/loopback.go
@@ -56,7 +56,7 @@ func (*endpoint) MTU() uint32 {
 // Capabilities implements stack.LinkEndpoint.Capabilities. Loopback advertises
 // itself as supporting checksum offload, but in reality it's just omitted.
 func (*endpoint) Capabilities() stack.LinkEndpointCapabilities {
-	return stack.CapabilityChecksumOffload | stack.CapabilitySaveRestore | stack.CapabilityLoopback
+	return stack.CapabilityRXChecksumOffload | stack.CapabilityTXChecksumOffload | stack.CapabilitySaveRestore | stack.CapabilityLoopback
 }
 
 // MaxHeaderLength implements stack.LinkEndpoint.MaxHeaderLength. Given that the
diff --git a/pkg/tcpip/link/muxed/injectable.go b/pkg/tcpip/link/muxed/injectable.go
index 99edc232d..b3e71c7fc 100644
--- a/pkg/tcpip/link/muxed/injectable.go
+++ b/pkg/tcpip/link/muxed/injectable.go
@@ -105,7 +105,7 @@ func (m *InjectableEndpoint) WriteRawPacket(dest tcpip.Address, packet []byte) *
 }
 
 // NewInjectableEndpoint creates a new multi-endpoint injectable endpoint.
-func NewInjectableEndpoint(routes map[tcpip.Address]stack.InjectableLinkEndpoint, mtu uint32) (tcpip.LinkEndpointID, *InjectableEndpoint) {
+func NewInjectableEndpoint(routes map[tcpip.Address]stack.InjectableLinkEndpoint) (tcpip.LinkEndpointID, *InjectableEndpoint) {
 	e := &InjectableEndpoint{
 		routes: routes,
 	}
diff --git a/pkg/tcpip/link/muxed/injectable_test.go b/pkg/tcpip/link/muxed/injectable_test.go
index 7d25effad..031449a05 100644
--- a/pkg/tcpip/link/muxed/injectable_test.go
+++ b/pkg/tcpip/link/muxed/injectable_test.go
@@ -87,8 +87,8 @@ func makeTestInjectableEndpoint(t *testing.T) (*InjectableEndpoint, *os.File, tc
 	if err != nil {
 		t.Fatal("Failed to create socket pair:", err)
 	}
-	_, underlyingEndpoint := fdbased.NewInjectable(pair[1], 6500)
+	_, underlyingEndpoint := fdbased.NewInjectable(pair[1], 6500, stack.CapabilityNone)
 	routes := map[tcpip.Address]stack.InjectableLinkEndpoint{dstIP: underlyingEndpoint}
-	_, endpoint := NewInjectableEndpoint(routes, 6500)
+	_, endpoint := NewInjectableEndpoint(routes)
 	return endpoint, os.NewFile(uintptr(pair[0]), "test route end"), dstIP
 }