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Remove some layers of indirection around FrameTooBigError handling

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This commit is contained in:
David Wragg committed 2015-03-05 15:13:30 +00:00
1 parent e543bff1ba
commit 5b66daf1e4
3 files changed
+33 -49
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router/crypto.go
+5 -8
View File
@@ -245,7 +245,7 @@ func (ne *NaClEncryptor) TotalLen() int {
// Frame Decryptors
type FrameConsumer func(*LocalConnection, *net.UDPAddr, []byte, []byte, uint16, []byte) error
type FrameConsumer func(*LocalConnection, *net.UDPAddr, []byte, []byte, uint16, []byte)
type Decryptor interface {
IterateFrames(FrameConsumer, *UDPPacket) error
@@ -281,7 +281,7 @@ func NewNonDecryptor(conn *LocalConnection) *NonDecryptor {
return &NonDecryptor{conn: conn}
}
func (nd *NonDecryptor) IterateFrames(fun FrameConsumer, packet *UDPPacket) error {
func (nd *NonDecryptor) IterateFrames(consumer FrameConsumer, packet *UDPPacket) error {
buf := packet.Packet
for len(buf) >= (2 + NameSize + NameSize) {
srcNameByte := buf[:NameSize]
@@ -295,10 +295,7 @@ func (nd *NonDecryptor) IterateFrames(fun FrameConsumer, packet *UDPPacket) erro
}
frame := buf[:length]
buf = buf[length:]
err := fun(nd.conn, packet.Sender, srcNameByte, dstNameByte, length, frame)
if err != nil {
return err
}
consumer(nd.conn, packet.Sender, srcNameByte, dstNameByte, length, frame)
}
if len(buf) > 0 {
return PacketDecodingError{Desc: fmt.Sprintf("%d octets of trailing garbage", len(buf))}
@@ -348,13 +345,13 @@ func (nd *NaClDecryptor) ReceiveNonce(msg []byte) {
}
}
func (nd *NaClDecryptor) IterateFrames(fun FrameConsumer, packet *UDPPacket) error {
func (nd *NaClDecryptor) IterateFrames(consumer FrameConsumer, packet *UDPPacket) error {
buf, err := nd.decrypt(packet.Packet)
if err != nil {
return PacketDecodingError{Fatal: true, Desc: fmt.Sprint("decryption failed; ", err)}
}
packet.Packet = buf
return nd.NonDecryptor.IterateFrames(fun, packet)
return nd.NonDecryptor.IterateFrames(consumer, packet)
}
func (nd *NaClDecryptor) decrypt(buf []byte) ([]byte, error) {
router/ethernet_decoder.go
+5 -17
View File
@@ -25,21 +25,7 @@ func (dec *EthernetDecoder) DecodeLayers(data []byte) error {
return dec.parser.DecodeLayers(data, &dec.decoded)
}
func (dec *EthernetDecoder) CheckFrameTooBig(err error, sendFrame func([]byte) error) error {
if ftbe, ok := err.(FrameTooBigError); ok {
// we know: 1. ip is valid, 2. it was ip and DF was set
icmpFrame, err := dec.formICMPMTUPacket(ftbe.EPMTU)
if err != nil {
return err
}
log.Printf("Sending ICMP 3,4 (%v -> %v): PMTU= %v\n", dec.ip.DstIP, dec.ip.SrcIP, ftbe.EPMTU)
return sendFrame(icmpFrame)
} else {
return err
}
}
func (dec *EthernetDecoder) formICMPMTUPacket(mtu int) ([]byte, error) {
func (dec *EthernetDecoder) sendICMPFragNeeded(mtu int, sendFrame func([]byte) error) error {
buf := gopacket.NewSerializeBuffer()
opts := gopacket.SerializeOptions{
FixLengths: true,
@@ -67,9 +53,11 @@ func (dec *EthernetDecoder) formICMPMTUPacket(mtu int) ([]byte, error) {
Seq: uint16(mtu)},
&payload)
if err != nil {
return []byte{}, err
return err
}
return buf.Bytes(), nil
log.Printf("Sending ICMP 3,4 (%v -> %v): PMTU= %v\n", dec.ip.DstIP, dec.ip.SrcIP, mtu)
return sendFrame(buf.Bytes())
}
var (
router/router.go
+23 -24
View File
@@ -105,8 +105,6 @@ func (router *Router) sniff(pio PacketSourceSink) {
log.Println("Sniffing traffic on", router.Iface)
dec := NewEthernetDecoder()
injectFrame := func(frame []byte) error { return pio.WritePacket(frame) }
checkFrameTooBig := func(err error) error { return dec.CheckFrameTooBig(err, injectFrame) }
mac := router.Iface.HardwareAddr
if router.Macs.Enter(mac, router.Ourself.Peer) {
log.Println("Discovered our MAC", mac)
@@ -116,12 +114,12 @@ func (router *Router) sniff(pio PacketSourceSink) {
pkt, err := pio.ReadPacket()
checkFatal(err)
router.LogFrame("Sniffed", pkt, nil)
checkWarn(router.handleCapturedPacket(pkt, dec, checkFrameTooBig))
checkWarn(router.handleCapturedPacket(pkt, dec, pio))
}
}()
}
func (router *Router) handleCapturedPacket(frameData []byte, dec *EthernetDecoder, checkFrameTooBig func(error) error) error {
func (router *Router) handleCapturedPacket(frameData []byte, dec *EthernetDecoder, po PacketSink) error {
dec.DecodeLayers(frameData)
decodedLen := len(dec.decoded)
if decodedLen == 0 {
@@ -163,7 +161,11 @@ func (router *Router) handleCapturedPacket(frameData []byte, dec *EthernetDecode
router.Ourself.Broadcast(df, frameCopy, dec)
return nil
} else {
return checkFrameTooBig(router.Ourself.Forward(dstPeer, df, frameCopy, dec))
err := router.Ourself.Forward(dstPeer, df, frameCopy, dec)
if ftbe, ok := err.(FrameTooBigError); ok {
err = dec.sendICMPFragNeeded(ftbe.EPMTU, po.WritePacket)
}
return err
}
}
@@ -267,32 +269,22 @@ func (router *Router) udpReader(conn *net.UDPConn, po PacketSink) {
}
func (router *Router) handleUDPPacketFunc(dec *EthernetDecoder, po PacketSink) FrameConsumer {
checkFrameTooBig := func(err error, srcPeer *Peer) error {
if err == nil { // optimisation: avoid closure creation in common case
return nil
}
return dec.CheckFrameTooBig(err,
func(icmpFrame []byte) error {
return router.Ourself.Forward(srcPeer, false, icmpFrame, nil)
})
}
return func(relayConn *LocalConnection, sender *net.UDPAddr, srcNameByte, dstNameByte []byte, frameLen uint16, frame []byte) error {
return func(relayConn *LocalConnection, sender *net.UDPAddr, srcNameByte, dstNameByte []byte, frameLen uint16, frame []byte) {
srcName := PeerNameFromBin(srcNameByte)
dstName := PeerNameFromBin(dstNameByte)
srcPeer, found := router.Peers.Fetch(srcName)
if !found {
return nil
return
}
dstPeer, found := router.Peers.Fetch(dstName)
if !found {
return nil
return
}
dec.DecodeLayers(frame)
decodedLen := len(dec.decoded)
if decodedLen == 0 {
return nil
return
}
// Handle special frames produced internally (rather than
// captured/forwarded) by the remote router.
@@ -306,7 +298,7 @@ func (router *Router) handleUDPPacketFunc(dec *EthernetDecoder, po PacketSink) F
if srcPeer != relayConn.Remote() || dstPeer != router.Ourself.Peer {
// A special frame not originating from the remote, or
// not for us? How odd; let's just drop it.
return nil
return
}
switch {
case frameLen == EthernetOverhead+8:
@@ -319,7 +311,7 @@ func (router *Router) handleUDPPacketFunc(dec *EthernetDecoder, po PacketSink) F
binary.BigEndian.PutUint16(frameLenBytes, uint16(frameLen-EthernetOverhead))
relayConn.SendProtocolMsg(ProtocolMsg{ProtocolPMTUVerified, frameLenBytes})
}
return nil
return
}
df := decodedLen == 2 && (dec.ip.Flags&layers.IPv4DontFragment != 0)
@@ -331,7 +323,16 @@ func (router *Router) handleUDPPacketFunc(dec *EthernetDecoder, po PacketSink) F
} else {
router.LogFrame("Relaying", frame, &dec.eth)
}
return checkFrameTooBig(router.Ourself.Relay(srcPeer, dstPeer, df, frame, dec), srcPeer)
err := router.Ourself.Relay(srcPeer, dstPeer, df, frame, dec)
if ftbe, ok := err.(FrameTooBigError); ok {
err = dec.sendICMPFragNeeded(ftbe.EPMTU, func(icmpFrame []byte) error {
return router.Ourself.Forward(srcPeer, false, icmpFrame, nil)
})
}
checkWarn(err)
return
}
srcMac := dec.eth.SrcMAC
@@ -348,8 +349,6 @@ func (router *Router) handleUDPPacketFunc(dec *EthernetDecoder, po PacketSink) F
router.LogFrame("Relaying broadcast", frame, &dec.eth)
router.Ourself.RelayBroadcast(srcPeer, df, frame, dec)
}
return nil
}
}