125 lines
3.9 KiB
Go
125 lines
3.9 KiB
Go
// Copyright 2018 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ipv4
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import (
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"encoding/binary"
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"gvisor.googlesource.com/gvisor/pkg/tcpip"
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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.IPv4(vv.First())
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// We don't use IsValid() here because ICMP only requires that the IP
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// header plus 8 bytes of the transport header be included. So it's
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// likely that it is truncated, which would cause IsValid to return
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// false.
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//
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// Drop packet if it doesn't have the basic IPv4 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.IPv4MinimumSize || h.SourceAddress() != e.id.LocalAddress {
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return
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}
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hlen := int(h.HeaderLength())
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if vv.Size() < hlen || h.FragmentOffset() != 0 {
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// We won't be able to handle this if it doesn't contain the
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// full IPv4 header, or if it's a fragment not at offset 0
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// (because it won't have the transport header).
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return
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}
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// Skip the ip header, then deliver control message.
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vv.TrimFront(hlen)
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p := h.TransportProtocol()
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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.ICMPv4MinimumSize {
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return
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}
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h := header.ICMPv4(v)
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switch h.Type() {
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case header.ICMPv4Echo:
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if len(v) < header.ICMPv4EchoMinimumSize {
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return
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}
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vv.TrimFront(header.ICMPv4MinimumSize)
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req := echoRequest{r: r.Clone(), v: vv.ToView()}
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select {
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case e.echoRequests <- req:
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default:
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req.r.Release()
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}
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case header.ICMPv4EchoReply:
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if len(v) < header.ICMPv4EchoMinimumSize {
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return
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}
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e.dispatcher.DeliverTransportPacket(r, header.ICMPv4ProtocolNumber, vv)
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case header.ICMPv4DstUnreachable:
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if len(v) < header.ICMPv4DstUnreachableMinimumSize {
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return
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}
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vv.TrimFront(header.ICMPv4DstUnreachableMinimumSize)
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switch h.Code() {
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case header.ICMPv4PortUnreachable:
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e.handleControl(stack.ControlPortUnreachable, 0, vv)
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case header.ICMPv4FragmentationNeeded:
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mtu := uint32(binary.BigEndian.Uint16(v[header.ICMPv4DstUnreachableMinimumSize-2:]))
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e.handleControl(stack.ControlPacketTooBig, calculateMTU(mtu), vv)
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}
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}
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// TODO: Handle other ICMP types.
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}
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type echoRequest struct {
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r stack.Route
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v buffer.View
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}
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func (e *endpoint) echoReplier() {
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for req := range e.echoRequests {
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sendPing4(&req.r, 0, req.v)
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req.r.Release()
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}
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}
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func sendPing4(r *stack.Route, code byte, data buffer.View) *tcpip.Error {
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hdr := buffer.NewPrependable(header.ICMPv4EchoMinimumSize + int(r.MaxHeaderLength()))
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icmpv4 := header.ICMPv4(hdr.Prepend(header.ICMPv4EchoMinimumSize))
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icmpv4.SetType(header.ICMPv4EchoReply)
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icmpv4.SetCode(code)
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copy(icmpv4[header.ICMPv4MinimumSize:], data)
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data = data[header.ICMPv4EchoMinimumSize-header.ICMPv4MinimumSize:]
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icmpv4.SetChecksum(^header.Checksum(icmpv4, header.Checksum(data, 0)))
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return r.WritePacket(&hdr, data, header.ICMPv4ProtocolNumber)
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}
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