Trim Network/Transport Endpoint/Protocol

* Remove Capabilities and NICID methods from NetworkEndpoint.

* Remove linkEP and stack parameters from NetworkProtocol.NewEndpoint.
The LinkEndpoint can be fetched from the NetworkInterface. The stack
is passed to the NetworkProtocol when it is created so the
NetworkEndpoint can get it from its protocol.

* Remove stack parameter from TransportProtocol.NewEndpoint.
Like the NetworkProtocol/Endpoint, the stack is passed to the
TransportProtocol when it is created.

PiperOrigin-RevId: 334332721

2 files changed, 15 insertions, 24 deletions

diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index 3e5cf2ad9..5c4f715d7 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -40,7 +40,7 @@ func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt *stack
 	// Drop packet if it doesn't have the basic IPv4 header or if the
 	// original source address doesn't match an address we own.
 	src := hdr.SourceAddress()
-	if e.stack.CheckLocalAddress(e.NICID(), ProtocolNumber, src) == 0 {
+	if e.protocol.stack.CheckLocalAddress(e.nic.ID(), ProtocolNumber, src) == 0 {
 		return
 	}
 
@@ -110,7 +110,7 @@ func (e *endpoint) handleICMP(r *stack.Route, pkt *stack.PacketBuffer) {
 			localAddr = ""
 		}
 
-		r, err := r.Stack().FindRoute(e.NICID(), localAddr, r.RemoteAddress, ProtocolNumber, false /* multicastLoop */)
+		r, err := r.Stack().FindRoute(e.nic.ID(), localAddr, r.RemoteAddress, ProtocolNumber, false /* multicastLoop */)
 		if err != nil {
 			// If we cannot find a route to the destination, silently drop the packet.
 			return
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 41f6914b9..7adf0fac3 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -59,7 +59,6 @@ type endpoint struct {
 	linkEP     stack.LinkEndpoint
 	dispatcher stack.TransportDispatcher
 	protocol   *protocol
-	stack      *stack.Stack
 
 	// enabled is set to 1 when the enpoint is enabled and 0 when it is
 	// disabled.
@@ -75,13 +74,12 @@ type endpoint struct {
 }
 
 // NewEndpoint creates a new ipv4 endpoint.
-func (p *protocol) NewEndpoint(nic stack.NetworkInterface, _ stack.LinkAddressCache, _ stack.NUDHandler, dispatcher stack.TransportDispatcher, linkEP stack.LinkEndpoint, st *stack.Stack) stack.NetworkEndpoint {
+func (p *protocol) NewEndpoint(nic stack.NetworkInterface, _ stack.LinkAddressCache, _ stack.NUDHandler, dispatcher stack.TransportDispatcher) stack.NetworkEndpoint {
 	e := &endpoint{
 		nic:        nic,
-		linkEP:     linkEP,
+		linkEP:     nic.LinkEndpoint(),
 		dispatcher: dispatcher,
 		protocol:   p,
-		stack:      st,
 	}
 	e.mu.addressableEndpointState.Init(e)
 	return e
@@ -173,16 +171,6 @@ func (e *endpoint) MTU() uint32 {
 	return calculateMTU(e.linkEP.MTU())
 }
 
-// Capabilities implements stack.NetworkEndpoint.
-func (e *endpoint) Capabilities() stack.LinkEndpointCapabilities {
-	return e.linkEP.Capabilities()
-}
-
-// NICID returns the ID of the NIC this endpoint belongs to.
-func (e *endpoint) NICID() tcpip.NICID {
-	return e.nic.ID()
-}
-
 // MaxHeaderLength returns the maximum length needed by ipv4 headers (and
 // underlying protocols).
 func (e *endpoint) MaxHeaderLength() uint16 {
@@ -324,8 +312,8 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 
 	// iptables filtering. All packets that reach here are locally
 	// generated.
-	nicName := e.stack.FindNICNameFromID(e.NICID())
-	ipt := e.stack.IPTables()
+	nicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
+	ipt := e.protocol.stack.IPTables()
 	if ok := ipt.Check(stack.Output, pkt, gso, r, "", nicName); !ok {
 		// iptables is telling us to drop the packet.
 		r.Stats().IP.IPTablesOutputDropped.Increment()
@@ -341,7 +329,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 	// short circuits broadcasts before they are sent out to other hosts.
 	if pkt.NatDone {
 		netHeader := header.IPv4(pkt.NetworkHeader().View())
-		ep, err := e.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress())
+		ep, err := e.protocol.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress())
 		if err == nil {
 			route := r.ReverseRoute(netHeader.SourceAddress(), netHeader.DestinationAddress())
 			ep.HandlePacket(&route, pkt)
@@ -381,10 +369,10 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 		pkt = pkt.Next()
 	}
 
-	nicName := e.stack.FindNICNameFromID(e.NICID())
+	nicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
 	// iptables filtering. All packets that reach here are locally
 	// generated.
-	ipt := e.stack.IPTables()
+	ipt := e.protocol.stack.IPTables()
 	dropped, natPkts := ipt.CheckPackets(stack.Output, pkts, gso, r, nicName)
 	if len(dropped) == 0 && len(natPkts) == 0 {
 		// Fast path: If no packets are to be dropped then we can just invoke the
@@ -404,7 +392,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 		}
 		if _, ok := natPkts[pkt]; ok {
 			netHeader := header.IPv4(pkt.NetworkHeader().View())
-			if ep, err := e.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress()); err == nil {
+			if ep, err := e.protocol.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress()); err == nil {
 				src := netHeader.SourceAddress()
 				dst := netHeader.DestinationAddress()
 				route := r.ReverseRoute(src, dst)
@@ -493,7 +481,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) {
 
 	// iptables filtering. All packets that reach here are intended for
 	// this machine and will not be forwarded.
-	ipt := e.stack.IPTables()
+	ipt := e.protocol.stack.IPTables()
 	if ok := ipt.Check(stack.Input, pkt, nil, nil, "", ""); !ok {
 		// iptables is telling us to drop the packet.
 		r.Stats().IP.IPTablesInputDropped.Increment()
@@ -677,6 +665,8 @@ var _ stack.ForwardingNetworkProtocol = (*protocol)(nil)
 var _ stack.NetworkProtocol = (*protocol)(nil)
 
 type protocol struct {
+	stack *stack.Stack
+
 	// defaultTTL is the current default TTL for the protocol. Only the
 	// uint8 portion of it is meaningful.
 	//
@@ -799,7 +789,7 @@ func hashRoute(r *stack.Route, protocol tcpip.TransportProtocolNumber, hashIV ui
 }
 
 // NewProtocol returns an IPv4 network protocol.
-func NewProtocol(*stack.Stack) stack.NetworkProtocol {
+func NewProtocol(s *stack.Stack) stack.NetworkProtocol {
 	ids := make([]uint32, buckets)
 
 	// Randomly initialize hashIV and the ids.
@@ -810,6 +800,7 @@ func NewProtocol(*stack.Stack) stack.NetworkProtocol {
 	hashIV := r[buckets]
 
 	return &protocol{
+		stack:         s,
 		ids:           ids,
 		hashIV:        hashIV,
 		defaultTTL:    DefaultTTL,