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Merge pull request #87 from AkihiroSuda/a
port/builtin: use libnetwork UDP proxy
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,150 @@ | ||
| // Package udpproxy is from https://raw.githubusercontent.com/docker/libnetwork/fec6476dfa21380bf8ee4d74048515d968c1ee63/cmd/proxy/udp_proxy.go | ||
| package udpproxy | ||
|
|
||
| import ( | ||
| "encoding/binary" | ||
| "fmt" | ||
| "io" | ||
| "net" | ||
| "strings" | ||
| "sync" | ||
| "syscall" | ||
| "time" | ||
| ) | ||
|
|
||
| const ( | ||
| // UDPConnTrackTimeout is the timeout used for UDP connection tracking | ||
| UDPConnTrackTimeout = 90 * time.Second | ||
| // UDPBufSize is the buffer size for the UDP proxy | ||
| UDPBufSize = 65507 | ||
| ) | ||
|
|
||
| // A net.Addr where the IP is split into two fields so you can use it as a key | ||
| // in a map: | ||
| type connTrackKey struct { | ||
| IPHigh uint64 | ||
| IPLow uint64 | ||
| Port int | ||
| } | ||
|
|
||
| func newConnTrackKey(addr *net.UDPAddr) *connTrackKey { | ||
| if len(addr.IP) == net.IPv4len { | ||
| return &connTrackKey{ | ||
| IPHigh: 0, | ||
| IPLow: uint64(binary.BigEndian.Uint32(addr.IP)), | ||
| Port: addr.Port, | ||
| } | ||
| } | ||
| return &connTrackKey{ | ||
| IPHigh: binary.BigEndian.Uint64(addr.IP[:8]), | ||
| IPLow: binary.BigEndian.Uint64(addr.IP[8:]), | ||
| Port: addr.Port, | ||
| } | ||
| } | ||
|
|
||
| type connTrackMap map[connTrackKey]*net.UDPConn | ||
|
|
||
| // UDPProxy is proxy for which handles UDP datagrams. | ||
| // From libnetwork udp_proxy.go . | ||
| type UDPProxy struct { | ||
| LogWriter io.Writer | ||
| Listener *net.UDPConn | ||
| BackendDial func() (*net.UDPConn, error) | ||
| connTrackTable connTrackMap | ||
| connTrackLock sync.Mutex | ||
| } | ||
|
|
||
| func (proxy *UDPProxy) replyLoop(proxyConn *net.UDPConn, clientAddr *net.UDPAddr, clientKey *connTrackKey) { | ||
| defer func() { | ||
| proxy.connTrackLock.Lock() | ||
| delete(proxy.connTrackTable, *clientKey) | ||
| proxy.connTrackLock.Unlock() | ||
| proxyConn.Close() | ||
| }() | ||
|
|
||
| readBuf := make([]byte, UDPBufSize) | ||
| for { | ||
| proxyConn.SetReadDeadline(time.Now().Add(UDPConnTrackTimeout)) | ||
| again: | ||
| read, err := proxyConn.Read(readBuf) | ||
| if err != nil { | ||
| if err, ok := err.(*net.OpError); ok && err.Err == syscall.ECONNREFUSED { | ||
| // This will happen if the last write failed | ||
| // (e.g: nothing is actually listening on the | ||
| // proxied port on the container), ignore it | ||
| // and continue until UDPConnTrackTimeout | ||
| // expires: | ||
| goto again | ||
| } | ||
| return | ||
| } | ||
| for i := 0; i != read; { | ||
| written, err := proxy.Listener.WriteToUDP(readBuf[i:read], clientAddr) | ||
| if err != nil { | ||
| return | ||
| } | ||
| i += written | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Run starts forwarding the traffic using UDP. | ||
| func (proxy *UDPProxy) Run() { | ||
| proxy.connTrackTable = make(connTrackMap) | ||
| readBuf := make([]byte, UDPBufSize) | ||
| for { | ||
| read, from, err := proxy.Listener.ReadFromUDP(readBuf) | ||
| if err != nil { | ||
| // NOTE: Apparently ReadFrom doesn't return | ||
| // ECONNREFUSED like Read do (see comment in | ||
| // UDPProxy.replyLoop) | ||
| if !isClosedError(err) { | ||
| fmt.Fprintf(proxy.LogWriter, "Stopping proxy on udp: %v\n", err) | ||
| } | ||
| break | ||
| } | ||
|
|
||
| fromKey := newConnTrackKey(from) | ||
| proxy.connTrackLock.Lock() | ||
| proxyConn, hit := proxy.connTrackTable[*fromKey] | ||
| if !hit { | ||
| proxyConn, err = proxy.BackendDial() | ||
| if err != nil { | ||
| fmt.Fprintf(proxy.LogWriter, "Can't proxy a datagram to udp: %v\n", err) | ||
| proxy.connTrackLock.Unlock() | ||
| continue | ||
| } | ||
| proxy.connTrackTable[*fromKey] = proxyConn | ||
| go proxy.replyLoop(proxyConn, from, fromKey) | ||
| } | ||
| proxy.connTrackLock.Unlock() | ||
| for i := 0; i != read; { | ||
| written, err := proxyConn.Write(readBuf[i:read]) | ||
| if err != nil { | ||
| fmt.Fprintf(proxy.LogWriter, "Can't proxy a datagram to udp: %v\n", err) | ||
| break | ||
| } | ||
| i += written | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Close stops forwarding the traffic. | ||
| func (proxy *UDPProxy) Close() { | ||
| proxy.Listener.Close() | ||
| proxy.connTrackLock.Lock() | ||
| defer proxy.connTrackLock.Unlock() | ||
| for _, conn := range proxy.connTrackTable { | ||
| conn.Close() | ||
| } | ||
| } | ||
|
|
||
| func isClosedError(err error) bool { | ||
| /* This comparison is ugly, but unfortunately, net.go doesn't export errClosing. | ||
| * See: | ||
| * http://golang.org/src/pkg/net/net.go | ||
| * https://code.google.com/p/go/issues/detail?id=4337 | ||
| * https://groups.google.com/forum/#!msg/golang-nuts/0_aaCvBmOcM/SptmDyX1XJMJ | ||
| */ | ||
| return strings.HasSuffix(err.Error(), "use of closed network connection") | ||
| } |