/
virtuallistener.go
175 lines (144 loc) · 3.94 KB
/
virtuallistener.go
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package libp2pquic
import (
"sync"
tpt "github.com/libp2p/go-libp2p/core/transport"
"github.com/libp2p/go-libp2p/p2p/transport/quicreuse"
ma "github.com/multiformats/go-multiaddr"
"github.com/quic-go/quic-go"
)
const acceptBufferPerVersion = 4
// virtualListener is a listener that exposes a single multiaddr but uses another listener under the hood
type virtualListener struct {
*listener
udpAddr string
version quic.VersionNumber
t *transport
acceptRunnner *acceptLoopRunner
acceptChan chan acceptVal
}
var _ tpt.Listener = &virtualListener{}
func (l *virtualListener) Multiaddr() ma.Multiaddr {
return l.listener.localMultiaddrs[l.version]
}
func (l *virtualListener) Close() error {
l.acceptRunnner.RmAcceptForVersion(l.version, tpt.ErrListenerClosed)
return l.t.CloseVirtualListener(l)
}
func (l *virtualListener) Accept() (tpt.CapableConn, error) {
return l.acceptRunnner.Accept(l.listener, l.version, l.acceptChan)
}
type acceptVal struct {
conn tpt.CapableConn
err error
}
type acceptLoopRunner struct {
acceptSem chan struct{}
muxerMu sync.Mutex
muxer map[quic.VersionNumber]chan acceptVal
muxerClosed bool
}
func (r *acceptLoopRunner) AcceptForVersion(v quic.VersionNumber) chan acceptVal {
r.muxerMu.Lock()
defer r.muxerMu.Unlock()
ch := make(chan acceptVal, acceptBufferPerVersion)
if _, ok := r.muxer[v]; ok {
panic("unexpected chan already found in accept muxer")
}
r.muxer[v] = ch
return ch
}
func (r *acceptLoopRunner) RmAcceptForVersion(v quic.VersionNumber, err error) {
r.muxerMu.Lock()
defer r.muxerMu.Unlock()
if r.muxerClosed {
// Already closed, all versions are removed
return
}
ch, ok := r.muxer[v]
if !ok {
panic("expected chan in accept muxer")
}
ch <- acceptVal{err: err}
delete(r.muxer, v)
}
func (r *acceptLoopRunner) sendErrAndClose(err error) {
r.muxerMu.Lock()
defer r.muxerMu.Unlock()
r.muxerClosed = true
for k, ch := range r.muxer {
select {
case ch <- acceptVal{err: err}:
default:
}
delete(r.muxer, k)
close(ch)
}
}
// innerAccept is the inner logic of the Accept loop. Assume caller holds the
// acceptSemaphore. May return both a nil conn and nil error if it didn't find a
// conn with the expected version
func (r *acceptLoopRunner) innerAccept(l *listener, expectedVersion quic.VersionNumber, bufferedConnChan chan acceptVal) (tpt.CapableConn, error) {
select {
// Check if we have a buffered connection first from an earlier Accept call
case v, ok := <-bufferedConnChan:
if !ok {
return nil, tpt.ErrListenerClosed
}
return v.conn, v.err
default:
}
conn, err := l.Accept()
if err != nil {
r.sendErrAndClose(err)
return nil, err
}
_, version, err := quicreuse.FromQuicMultiaddr(conn.RemoteMultiaddr())
if err != nil {
r.sendErrAndClose(err)
return nil, err
}
if version == expectedVersion {
return conn, nil
}
// This wasn't the version we were expecting, lets queue it up for a
// future Accept call with a different version
r.muxerMu.Lock()
ch, ok := r.muxer[version]
r.muxerMu.Unlock()
if !ok {
// Nothing to handle this connection version. Close it
conn.Close()
return nil, nil
}
// Non blocking
select {
case ch <- acceptVal{conn: conn}:
default:
// accept queue filled up, drop the connection
conn.Close()
log.Warn("Accept queue filled. Dropping connection.")
}
return nil, nil
}
func (r *acceptLoopRunner) Accept(l *listener, expectedVersion quic.VersionNumber, bufferedConnChan chan acceptVal) (tpt.CapableConn, error) {
for {
var conn tpt.CapableConn
var err error
select {
case r.acceptSem <- struct{}{}:
conn, err = r.innerAccept(l, expectedVersion, bufferedConnChan)
<-r.acceptSem
if conn == nil && err == nil {
// Didn't find a conn for the expected version and there was no error, lets try again
continue
}
case v, ok := <-bufferedConnChan:
if !ok {
return nil, tpt.ErrListenerClosed
}
conn = v.conn
err = v.err
}
return conn, err
}
}