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