diff options
| author | Ghanan Gowripalan <ghanan@google.com> | 2020-10-08 16:14:01 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2020-10-08 16:15:59 -0700 |
| commit | 6768e6c59ec252854a1633e184b69dc5723ac3f3 (patch) | |
| tree | 9e9915094781b9b31b201434c7a1e1f0940c2869 /pkg/tcpip/network/arp | |
| parent | 40269d0c24d1ea9b040a8326c9fa01b03477410a (diff) | |
Do not resolve routes immediately
When a response needs to be sent to an incoming packet, the stack should
consult its neighbour table to determine the remote address's link
address.
When an entry does not exist in the stack's neighbor table, the stack
should queue the packet while link resolution completes. See comments.
PiperOrigin-RevId: 336185457
Diffstat (limited to 'pkg/tcpip/network/arp')
| -rw-r--r-- | pkg/tcpip/network/arp/arp.go | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/pkg/tcpip/network/arp/arp.go b/pkg/tcpip/network/arp/arp.go index b47a7be51..7df77c66e 100644 --- a/pkg/tcpip/network/arp/arp.go +++ b/pkg/tcpip/network/arp/arp.go @@ -49,7 +49,6 @@ type endpoint struct { enabled uint32 nic stack.NetworkInterface - linkEP stack.LinkEndpoint linkAddrCache stack.LinkAddressCache nud stack.NUDHandler } @@ -92,12 +91,12 @@ func (e *endpoint) DefaultTTL() uint8 { } func (e *endpoint) MTU() uint32 { - lmtu := e.linkEP.MTU() + lmtu := e.nic.MTU() return lmtu - uint32(e.MaxHeaderLength()) } func (e *endpoint) MaxHeaderLength() uint16 { - return e.linkEP.MaxHeaderLength() + header.ARPSize + return e.nic.MaxHeaderLength() + header.ARPSize } func (e *endpoint) Close() { @@ -154,17 +153,25 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) { e.nud.HandleProbe(remoteAddr, localAddr, ProtocolNumber, remoteLinkAddr, e.protocol) } - pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ - ReserveHeaderBytes: int(e.linkEP.MaxHeaderLength()) + header.ARPSize, + // As per RFC 826, under Packet Reception: + // Swap hardware and protocol fields, putting the local hardware and + // protocol addresses in the sender fields. + // + // Send the packet to the (new) target hardware address on the same + // hardware on which the request was received. + origSender := h.HardwareAddressSender() + r.RemoteLinkAddress = tcpip.LinkAddress(origSender) + respPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ + ReserveHeaderBytes: int(e.nic.MaxHeaderLength()) + header.ARPSize, }) - packet := header.ARP(pkt.NetworkHeader().Push(header.ARPSize)) + packet := header.ARP(respPkt.NetworkHeader().Push(header.ARPSize)) packet.SetIPv4OverEthernet() packet.SetOp(header.ARPReply) copy(packet.HardwareAddressSender(), r.LocalLinkAddress[:]) copy(packet.ProtocolAddressSender(), h.ProtocolAddressTarget()) - copy(packet.HardwareAddressTarget(), h.HardwareAddressSender()) + copy(packet.HardwareAddressTarget(), origSender) copy(packet.ProtocolAddressTarget(), h.ProtocolAddressSender()) - _ = e.linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, pkt) + _ = e.nic.WritePacket(r, nil /* gso */, ProtocolNumber, respPkt) case header.ARPReply: addr := tcpip.Address(h.ProtocolAddressSender()) @@ -207,7 +214,6 @@ func (p *protocol) NewEndpoint(nic stack.NetworkInterface, linkAddrCache stack.L e := &endpoint{ protocol: p, nic: nic, - linkEP: nic.LinkEndpoint(), linkAddrCache: linkAddrCache, nud: nud, } @@ -223,6 +229,7 @@ func (*protocol) LinkAddressProtocol() tcpip.NetworkProtocolNumber { // LinkAddressRequest implements stack.LinkAddressResolver.LinkAddressRequest. func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, remoteLinkAddr tcpip.LinkAddress, linkEP stack.LinkEndpoint) *tcpip.Error { r := &stack.Route{ + NetProto: ProtocolNumber, RemoteLinkAddress: remoteLinkAddr, } if len(r.RemoteLinkAddress) == 0 { |