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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package stack
import (
"sync"
"gvisor.googlesource.com/gvisor/pkg/tcpip"
"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
"gvisor.googlesource.com/gvisor/pkg/tcpip/header"
)
type protocolIDs struct {
network tcpip.NetworkProtocolNumber
transport tcpip.TransportProtocolNumber
}
// transportEndpoints manages all endpoints of a given protocol. It has its own
// mutex so as to reduce interference between protocols.
type transportEndpoints struct {
mu sync.RWMutex
endpoints map[TransportEndpointID]TransportEndpoint
}
// transportDemuxer demultiplexes packets targeted at a transport endpoint
// (i.e., after they've been parsed by the network layer). It does two levels
// of demultiplexing: first based on the network and transport protocols, then
// based on endpoints IDs.
type transportDemuxer struct {
protocol map[protocolIDs]*transportEndpoints
}
func newTransportDemuxer(stack *Stack) *transportDemuxer {
d := &transportDemuxer{protocol: make(map[protocolIDs]*transportEndpoints)}
// Add each network and transport pair to the demuxer.
for netProto := range stack.networkProtocols {
for proto := range stack.transportProtocols {
d.protocol[protocolIDs{netProto, proto}] = &transportEndpoints{endpoints: make(map[TransportEndpointID]TransportEndpoint)}
}
}
return d
}
// registerEndpoint registers the given endpoint with the dispatcher such that
// packets that match the endpoint ID are delivered to it.
func (d *transportDemuxer) registerEndpoint(netProtos []tcpip.NetworkProtocolNumber, protocol tcpip.TransportProtocolNumber, id TransportEndpointID, ep TransportEndpoint) *tcpip.Error {
for i, n := range netProtos {
if err := d.singleRegisterEndpoint(n, protocol, id, ep); err != nil {
d.unregisterEndpoint(netProtos[:i], protocol, id)
return err
}
}
return nil
}
func (d *transportDemuxer) singleRegisterEndpoint(netProto tcpip.NetworkProtocolNumber, protocol tcpip.TransportProtocolNumber, id TransportEndpointID, ep TransportEndpoint) *tcpip.Error {
eps, ok := d.protocol[protocolIDs{netProto, protocol}]
if !ok {
return nil
}
eps.mu.Lock()
defer eps.mu.Unlock()
if _, ok := eps.endpoints[id]; ok {
return tcpip.ErrPortInUse
}
eps.endpoints[id] = ep
return nil
}
// unregisterEndpoint unregisters the endpoint with the given id such that it
// won't receive any more packets.
func (d *transportDemuxer) unregisterEndpoint(netProtos []tcpip.NetworkProtocolNumber, protocol tcpip.TransportProtocolNumber, id TransportEndpointID) {
for _, n := range netProtos {
if eps, ok := d.protocol[protocolIDs{n, protocol}]; ok {
eps.mu.Lock()
delete(eps.endpoints, id)
eps.mu.Unlock()
}
}
}
// deliverPacket attempts to deliver the given packet. Returns true if it found
// an endpoint, false otherwise.
func (d *transportDemuxer) deliverPacket(r *Route, protocol tcpip.TransportProtocolNumber, vv buffer.VectorisedView, id TransportEndpointID) bool {
eps, ok := d.protocol[protocolIDs{r.NetProto, protocol}]
if !ok {
return false
}
eps.mu.RLock()
ep := d.findEndpointLocked(eps, vv, id)
eps.mu.RUnlock()
// Fail if we didn't find one.
if ep == nil {
// UDP packet could not be delivered to an unknown destination port.
if protocol == header.UDPProtocolNumber {
r.Stats().UDP.UnknownPortErrors.Increment()
}
return false
}
// Deliver the packet.
ep.HandlePacket(r, id, vv)
return true
}
// deliverControlPacket attempts to deliver the given control packet. Returns
// true if it found an endpoint, false otherwise.
func (d *transportDemuxer) deliverControlPacket(net tcpip.NetworkProtocolNumber, trans tcpip.TransportProtocolNumber, typ ControlType, extra uint32, vv buffer.VectorisedView, id TransportEndpointID) bool {
eps, ok := d.protocol[protocolIDs{net, trans}]
if !ok {
return false
}
// Try to find the endpoint.
eps.mu.RLock()
ep := d.findEndpointLocked(eps, vv, id)
eps.mu.RUnlock()
// Fail if we didn't find one.
if ep == nil {
return false
}
// Deliver the packet.
ep.HandleControlPacket(id, typ, extra, vv)
return true
}
func (d *transportDemuxer) findEndpointLocked(eps *transportEndpoints, vv buffer.VectorisedView, id TransportEndpointID) TransportEndpoint {
// Try to find a match with the id as provided.
if ep := eps.endpoints[id]; ep != nil {
return ep
}
// Try to find a match with the id minus the local address.
nid := id
nid.LocalAddress = ""
if ep := eps.endpoints[nid]; ep != nil {
return ep
}
// Try to find a match with the id minus the remote part.
nid.LocalAddress = id.LocalAddress
nid.RemoteAddress = ""
nid.RemotePort = 0
if ep := eps.endpoints[nid]; ep != nil {
return ep
}
// Try to find a match with only the local port.
nid.LocalAddress = ""
return eps.endpoints[nid]
}
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