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// Copyright 2017 The Netstack Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ipv6
import (
"encoding/binary"
"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
"gvisor.googlesource.com/gvisor/pkg/tcpip/header"
"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
)
// handleControl handles the case when an ICMP packet contains the headers of
// the original packet that caused the ICMP one to be sent. This information is
// used to find out which transport endpoint must be notified about the ICMP
// packet.
func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, vv *buffer.VectorisedView) {
h := header.IPv6(vv.First())
// We don't use IsValid() here because ICMP only requires that up to
// 1280 bytes of the original packet be included. So it's likely that it
// is truncated, which would cause IsValid to return false.
//
// Drop packet if it doesn't have the basic IPv6 header or if the
// original source address doesn't match the endpoint's address.
if len(h) < header.IPv6MinimumSize || h.SourceAddress() != e.id.LocalAddress {
return
}
// Skip the IP header, then handle the fragmentation header if there
// is one.
vv.TrimFront(header.IPv6MinimumSize)
p := h.TransportProtocol()
if p == header.IPv6FragmentHeader {
f := header.IPv6Fragment(vv.First())
if !f.IsValid() || f.FragmentOffset() != 0 {
// We can't handle fragments that aren't at offset 0
// because they don't have the transport headers.
return
}
// Skip fragmentation header and find out the actual protocol
// number.
vv.TrimFront(header.IPv6FragmentHeaderSize)
p = f.TransportProtocol()
}
// Deliver the control packet to the transport endpoint.
e.dispatcher.DeliverTransportControlPacket(e.id.LocalAddress, h.DestinationAddress(), ProtocolNumber, p, typ, extra, vv)
}
func (e *endpoint) handleICMP(r *stack.Route, vv *buffer.VectorisedView) {
v := vv.First()
if len(v) < header.ICMPv6MinimumSize {
return
}
h := header.ICMPv6(v)
switch h.Type() {
case header.ICMPv6PacketTooBig:
if len(v) < header.ICMPv6PacketTooBigMinimumSize {
return
}
vv.TrimFront(header.ICMPv6PacketTooBigMinimumSize)
mtu := binary.BigEndian.Uint32(v[header.ICMPv6MinimumSize:])
e.handleControl(stack.ControlPacketTooBig, calculateMTU(mtu), vv)
case header.ICMPv6DstUnreachable:
if len(v) < header.ICMPv6DstUnreachableMinimumSize {
return
}
vv.TrimFront(header.ICMPv6DstUnreachableMinimumSize)
switch h.Code() {
case header.ICMPv6PortUnreachable:
e.handleControl(stack.ControlPortUnreachable, 0, vv)
}
}
}
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