132 lines
3.4 KiB
Go
132 lines
3.4 KiB
Go
// Copyright 2020 The gVisor Authors.
|
|
//
|
|
// 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 (
|
|
"fmt"
|
|
|
|
"gvisor.dev/gvisor/pkg/sync"
|
|
"gvisor.dev/gvisor/pkg/tcpip"
|
|
)
|
|
|
|
const (
|
|
// maxPendingResolutions is the maximum number of pending link-address
|
|
// resolutions.
|
|
maxPendingResolutions = 64
|
|
maxPendingPacketsPerResolution = 256
|
|
)
|
|
|
|
type pendingPacket struct {
|
|
nic *NIC
|
|
route *Route
|
|
proto tcpip.NetworkProtocolNumber
|
|
pkt *PacketBuffer
|
|
}
|
|
|
|
type forwardQueue struct {
|
|
sync.Mutex
|
|
|
|
// The packets to send once the resolver completes.
|
|
packets map[<-chan struct{}][]*pendingPacket
|
|
|
|
// FIFO of channels used to cancel the oldest goroutine waiting for
|
|
// link-address resolution.
|
|
cancelChans []chan struct{}
|
|
}
|
|
|
|
func newForwardQueue() *forwardQueue {
|
|
return &forwardQueue{packets: make(map[<-chan struct{}][]*pendingPacket)}
|
|
}
|
|
|
|
func (f *forwardQueue) enqueue(ch <-chan struct{}, n *NIC, r *Route, protocol tcpip.NetworkProtocolNumber, pkt *PacketBuffer) {
|
|
shouldWait := false
|
|
|
|
f.Lock()
|
|
packets, ok := f.packets[ch]
|
|
if !ok {
|
|
shouldWait = true
|
|
}
|
|
for len(packets) == maxPendingPacketsPerResolution {
|
|
p := packets[0]
|
|
packets = packets[1:]
|
|
p.nic.stack.stats.IP.OutgoingPacketErrors.Increment()
|
|
p.route.Release()
|
|
}
|
|
if l := len(packets); l >= maxPendingPacketsPerResolution {
|
|
panic(fmt.Sprintf("max pending packets for resolution reached; got %d packets, max = %d", l, maxPendingPacketsPerResolution))
|
|
}
|
|
f.packets[ch] = append(packets, &pendingPacket{
|
|
nic: n,
|
|
route: r,
|
|
proto: protocol,
|
|
pkt: pkt,
|
|
})
|
|
f.Unlock()
|
|
|
|
if !shouldWait {
|
|
return
|
|
}
|
|
|
|
// Wait for the link-address resolution to complete.
|
|
// Start a goroutine with a forwarding-cancel channel so that we can
|
|
// limit the maximum number of goroutines running concurrently.
|
|
cancel := f.newCancelChannel()
|
|
go func() {
|
|
cancelled := false
|
|
select {
|
|
case <-ch:
|
|
case <-cancel:
|
|
cancelled = true
|
|
}
|
|
|
|
f.Lock()
|
|
packets := f.packets[ch]
|
|
delete(f.packets, ch)
|
|
f.Unlock()
|
|
|
|
for _, p := range packets {
|
|
if cancelled {
|
|
p.nic.stack.stats.IP.OutgoingPacketErrors.Increment()
|
|
} else if _, err := p.route.Resolve(nil); err != nil {
|
|
p.nic.stack.stats.IP.OutgoingPacketErrors.Increment()
|
|
} else {
|
|
p.nic.forwardPacket(p.route, p.proto, p.pkt)
|
|
}
|
|
p.route.Release()
|
|
}
|
|
}()
|
|
}
|
|
|
|
// newCancelChannel creates a channel that can cancel a pending forwarding
|
|
// activity. The oldest channel is closed if the number of open channels would
|
|
// exceed maxPendingResolutions.
|
|
func (f *forwardQueue) newCancelChannel() chan struct{} {
|
|
f.Lock()
|
|
defer f.Unlock()
|
|
|
|
if len(f.cancelChans) == maxPendingResolutions {
|
|
ch := f.cancelChans[0]
|
|
f.cancelChans = f.cancelChans[1:]
|
|
close(ch)
|
|
}
|
|
if l := len(f.cancelChans); l >= maxPendingResolutions {
|
|
panic(fmt.Sprintf("max pending resolutions reached; got %d active resolutions, max = %d", l, maxPendingResolutions))
|
|
}
|
|
|
|
ch := make(chan struct{})
|
|
f.cancelChans = append(f.cancelChans, ch)
|
|
return ch
|
|
}
|