WIP Dont fragment

1 files changed, 10 insertions, 2 deletions

diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index c0af9a2d8..18078c74c 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -243,8 +243,10 @@ func (e *endpoint) addIPHeader(r *stack.Route, hdr *buffer.Prependable, payloadS
 
 // 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 tcpip.PacketBuffer) *tcpip.Error {
-	ip := e.addIPHeader(r, &pkt.Header, pkt.Data.Size(), params)
-	pkt.NetworkHeader = buffer.View(ip)
+	if !params.Forwarded {
+		ip := e.addIPHeader(r, &pkt.Header, pkt.Data.Size(), params)
+		pkt.NetworkHeader = buffer.View(ip)
+	}
 
 	if r.Loop&stack.PacketLoop != 0 {
 		// The inbound path expects the network header to still be in
@@ -264,6 +266,12 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 		return nil
 	}
 	if pkt.Header.UsedLength()+pkt.Data.Size() > int(e.linkEP.MTU()) && (gso == nil || gso.Type == stack.GSONone) {
+		h := header.IPv4(pkt.Header.View())
+		fmt.Println("DF: ", pkt.Header.UsedLength(), pkt.Data.Size(), e.linkEP.MTU())
+		if params.Forwarded && (h.Flags() & header.IPv4FlagDontFragment) != 0 {
+			e.SendIcmp(pkt, header.ICMPv4DstUnreachable, header.ICMPv4FragmentationNeeded, uint16(e.linkEP.MTU()))
+			return nil // FIXME
+		}
 		return e.writePacketFragments(r, gso, int(e.linkEP.MTU()), pkt)
 	}
 	if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, pkt); err != nil {