Introduce IPv4 options serializer and add RouterAlert to IGMP

PiperOrigin-RevId: 345701623

1 files changed, 14 insertions, 17 deletions

diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 354ac1e1d..4b34d0bfb 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -215,21 +215,18 @@ func (e *endpoint) NetworkProtocolNumber() tcpip.NetworkProtocolNumber {
 	return e.protocol.Number()
 }
 
-func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.PacketBuffer, params stack.NetworkHeaderParams) {
+func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.PacketBuffer, params stack.NetworkHeaderParams, options header.IPv4OptionsSerializer) {
 	hdrLen := header.IPv4MinimumSize
-	var opts header.IPv4Options
-	if params.Options != nil {
-		var ok bool
-		if opts, ok = params.Options.(header.IPv4Options); !ok {
-			panic(fmt.Sprintf("want IPv4Options, got %T", params.Options))
-		}
-		hdrLen += opts.SizeWithPadding()
-		if hdrLen > header.IPv4MaximumHeaderSize {
-			// Since we have no way to report an error we must either panic or create
-			// a packet which is different to what was requested. Choose panic as this
-			// would be a programming error that should be caught in testing.
-			panic(fmt.Sprintf("IPv4 Options %d bytes, Max %d", params.Options.SizeWithPadding(), header.IPv4MaximumOptionsSize))
-		}
+	var optLen int
+	if options != nil {
+		optLen = int(options.Length())
+	}
+	hdrLen += optLen
+	if hdrLen > header.IPv4MaximumHeaderSize {
+		// Since we have no way to report an error we must either panic or create
+		// a packet which is different to what was requested. Choose panic as this
+		// would be a programming error that should be caught in testing.
+		panic(fmt.Sprintf("IPv4 Options %d bytes, Max %d", optLen, header.IPv4MaximumOptionsSize))
 	}
 	ip := header.IPv4(pkt.NetworkHeader().Push(hdrLen))
 	length := uint16(pkt.Size())
@@ -245,7 +242,7 @@ func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.Packet
 		Protocol:    uint8(params.Protocol),
 		SrcAddr:     srcAddr,
 		DstAddr:     dstAddr,
-		Options:     opts,
+		Options:     options,
 	})
 	ip.SetChecksum(^ip.CalculateChecksum())
 	pkt.NetworkProtocolNumber = ProtocolNumber
@@ -276,7 +273,7 @@ func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU ui
 
 // WritePacket writes a packet to the given destination address and protocol.
 func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) *tcpip.Error {
-	e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params)
+	e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params, nil /* options */)
 
 	// iptables filtering. All packets that reach here are locally
 	// generated.
@@ -364,7 +361,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 	}
 
 	for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
-		e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params)
+		e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params, nil /* options */)
 		networkMTU, err := calculateNetworkMTU(e.nic.MTU(), uint32(pkt.NetworkHeader().View().Size()))
 		if err != nil {
 			r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(pkts.Len()))