From 7d8e321a65ee1dc2659b41ad13370f5a530c498e Mon Sep 17 00:00:00 2001
From: Mikael Magnusson <mikma@users.sourceforge.net>
Date: Tue, 17 Mar 2020 20:03:03 +0100
Subject: WIP SendIcmp

---
 pkg/tcpip/network/ipv4/ipv4.go | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 9953f83cd..c0af9a2d8 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -408,6 +408,42 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt tcpip.PacketBuffer) {
 	e.dispatcher.DeliverTransportPacket(r, p, pkt)
 }
 
+func (e *endpoint) SendIcmp(pkt tcpip.PacketBuffer, icmpv4type header.ICMPv4Type, icmpv4code byte, nextHopMtu uint16) *tcpip.Error {
+	headerView := pkt.Header.View()
+	h := header.IPv4(headerView)
+	vv := headerView.ToVectorisedView()
+	vv.Append(pkt.Data.Clone(nil))
+	fmt.Println("SendIcmp ", vv.Size())
+	hdr := buffer.NewPrependable(int(e.MaxHeaderLength()) + header.ICMPv4MinimumSize)
+	icmp := header.ICMPv4(hdr.Prepend(header.ICMPv4MinimumSize))
+	copy(icmp, h)
+	icmp.SetType(icmpv4type)
+	icmp.SetCode(icmpv4code)
+	if nextHopMtu != 0 {
+		icmp.SetMTU(nextHopMtu)
+	}
+	icmp.SetChecksum(0)
+	icmp.SetChecksum(^header.Checksum(icmp, header.ChecksumVV(vv, 0)))
+	//sent := stats.ICMP.V4PacketsSent
+	r, err := e.stack.FindRoute(0, "", h.SourceAddress(), ProtocolNumber, false /* multicastLoop */)
+	if err != nil {
+		fmt.Println("FindRoute error ", err)
+		return tcpip.ErrInvalidOptionValue
+	}
+	ttl := r.DefaultTTL()
+	if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv4ProtocolNumber, TTL: ttl, TOS: stack.DefaultTOS}, tcpip.PacketBuffer{
+		Header:          hdr,
+		Data:            vv,
+//		TransportHeader: buffer.View(icmp),
+	}); err != nil {
+		//sent.Dropped.Increment()
+		fmt.Println("WritePacket error ", err)
+		return tcpip.ErrInvalidOptionValue
+	}
+
+	return nil
+}
+
 func (*endpoint) UpdateTTL(pkt tcpip.PacketBuffer, n uint8) *tcpip.Error {
 	headerView := pkt.Header.View()
 	h := header.IPv4(headerView)
-- 
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