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// Copyright 2019 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 muxed provides a muxed link endpoints.
package muxed
import (
"gvisor.googlesource.com/gvisor/pkg/tcpip"
"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
)
// InjectableEndpoint is an injectable multi endpoint. The endpoint has
// trivial routing rules that determine which InjectableEndpoint a given packet
// will be written to. Note that HandleLocal works differently for this
// endpoint (see WritePacket).
type InjectableEndpoint struct {
routes map[tcpip.Address]stack.InjectableLinkEndpoint
dispatcher stack.NetworkDispatcher
}
// MTU implements stack.LinkEndpoint.
func (m *InjectableEndpoint) MTU() uint32 {
minMTU := ^uint32(0)
for _, endpoint := range m.routes {
if endpointMTU := endpoint.MTU(); endpointMTU < minMTU {
minMTU = endpointMTU
}
}
return minMTU
}
// Capabilities implements stack.LinkEndpoint.
func (m *InjectableEndpoint) Capabilities() stack.LinkEndpointCapabilities {
minCapabilities := stack.LinkEndpointCapabilities(^uint(0))
for _, endpoint := range m.routes {
minCapabilities &= endpoint.Capabilities()
}
return minCapabilities
}
// MaxHeaderLength implements stack.LinkEndpoint.
func (m *InjectableEndpoint) MaxHeaderLength() uint16 {
minHeaderLen := ^uint16(0)
for _, endpoint := range m.routes {
if headerLen := endpoint.MaxHeaderLength(); headerLen < minHeaderLen {
minHeaderLen = headerLen
}
}
return minHeaderLen
}
// LinkAddress implements stack.LinkEndpoint.
func (m *InjectableEndpoint) LinkAddress() tcpip.LinkAddress {
return ""
}
// Attach implements stack.LinkEndpoint.
func (m *InjectableEndpoint) Attach(dispatcher stack.NetworkDispatcher) {
for _, endpoint := range m.routes {
endpoint.Attach(dispatcher)
}
m.dispatcher = dispatcher
}
// IsAttached implements stack.LinkEndpoint.
func (m *InjectableEndpoint) IsAttached() bool {
return m.dispatcher != nil
}
// Inject implements stack.InjectableLinkEndpoint.
func (m *InjectableEndpoint) Inject(protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView) {
m.dispatcher.DeliverNetworkPacket(m, "" /* remote */, "" /* local */, protocol, vv)
}
// WritePacket writes outbound packets to the appropriate LinkInjectableEndpoint
// based on the RemoteAddress. HandleLocal only works if r.RemoteAddress has a
// route registered in this endpoint.
func (m *InjectableEndpoint) WritePacket(r *stack.Route, hdr buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.NetworkProtocolNumber) *tcpip.Error {
if endpoint, ok := m.routes[r.RemoteAddress]; ok {
return endpoint.WritePacket(r, hdr, payload, protocol)
}
return tcpip.ErrNoRoute
}
// WriteRawPacket writes outbound packets to the appropriate
// LinkInjectableEndpoint based on the dest address.
func (m *InjectableEndpoint) WriteRawPacket(dest tcpip.Address, packet []byte) *tcpip.Error {
endpoint, ok := m.routes[dest]
if !ok {
return tcpip.ErrNoRoute
}
return endpoint.WriteRawPacket(dest, packet)
}
// NewInjectableEndpoint creates a new multi-endpoint injectable endpoint.
func NewInjectableEndpoint(routes map[tcpip.Address]stack.InjectableLinkEndpoint, mtu uint32) (tcpip.LinkEndpointID, *InjectableEndpoint) {
e := &InjectableEndpoint{
routes: routes,
}
return stack.RegisterLinkEndpoint(e), e
}
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