Websockify não transmite mais informações, a conexão é interrompida prematuramente

1

Eu preciso usar websockify como proxy. A configuração final será:

  • um websocket em uma página da web se conecta a websockify server na mesma máquina
  • O servidor websockify inicia a conexão com um programa de soquete TCP escutando em algum outro lugar (neste caso, a mesma máquina)
  • O soquete TCP recebe informações, executa cálculos, responde websockify
  • websockify obtém a resposta e envia as informações para o soquete na página da Web
  • a resposta é apresentada no navegador do usuário

No entanto, por algum motivo, websockify se recusa a passar mais as informações e recebe a mensagem FIN mais cedo do que o esperado. Websockify diz "Não suportado: opcode desconhecido 0x01".

Para investigar este caso, criei um tráfego MWE e interceptado com tcpdump .

A configuração é a seguinte:

  • Primeiramente, eu corro netcat -v -v -l -p 40000 - esse é o aplicativo que queremos receber as informações

  • Em seguida, corro websockify --verbose 50000 localhost:40000 - esse é o comando de proxy

  • Por fim, corro wscat -c localhost:50000 - esse é um aplicativo que faz uma conexão de websocket com websockify proxy

Assim que eu enviar algo com wscat , a conexão de wscat será descartada com o código 1003. Citando RFC 6455 :

1003 indicates that an endpoint is terminating the connection because it has received a type of data it cannot accept (e.g., an endpoint that understands only text data MAY send this if it receives a binary message).

Aqui está a representação visual dessa configuração (a mensagem erorr 'disconnected because closed 1003' está escrita dessa maneira porque alterei manualmente a fonte para extrair mais informações sobre a desconexão):

AquiestáarepresentaçãodosdadosdoWireshark:

e aqui estão os números dos pacotes 11,12,13 e 14 que me chamaram a atenção:

Frame 11: 81 bytes on wire (648 bits), 81 bytes captured (648 bits)
    Encapsulation type: Ethernet (1)
    Arrival Time: Sep 19, 2017 20:35:46.491762000 CEST
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1505846146.491762000 seconds
    [Time delta from previous captured frame: 3.788711000 seconds]
    [Time delta from previous displayed frame: 3.788711000 seconds]
    [Time since reference or first frame: 3.887638000 seconds]
    Frame Number: 11
    Frame Length: 81 bytes (648 bits)
    Capture Length: 81 bytes (648 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ethertype:ip:tcp:http:websocket:data-text-lines]
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)
    Destination: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Source: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
    0100 .... = Version: 4
    .... 0101 = Header Length: 20 bytes (5)
    Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
        0000 00.. = Differentiated Services Codepoint: Default (0)
        .... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    Total Length: 67
    Identification: 0x1581 (5505)
    Flags: 0x02 (Don't Fragment)
        0... .... = Reserved bit: Not set
        .1.. .... = Don't fragment: Set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: TCP (6)
    Header checksum: 0x2732 [validation disabled]
    [Header checksum status: Unverified]
    Source: 127.0.0.1
    Destination: 127.0.0.1
    [Source GeoIP: Unknown]
    [Destination GeoIP: Unknown]
TCP Src Port: 53832, Dst Port: 50000, Seq: 225, Ack: 130, Len: 15
    Src Port: 53832
    Dest Port: 50000
    [Stream index: 0]
    [TCP Segment Len: 15]
    Sequence number: 225    (relative sequence number)
    [Next sequence number: 240    (relative sequence number)]
    Acknowledgment number: 130    (relative ack number)
    1000 .... = Header Length: 32 bytes (8)
    Flags: 0x018 (PSH, ACK)
        000. .... .... = Reserved: Not set
        ...0 .... .... = Nonce: Not set
        .... 0... .... = Congestion Window Reduced (CWR): Not set
        .... .0.. .... = ECN-Echo: Not set
        .... ..0. .... = Urgent: Not set
        .... ...1 .... = Acknowledgment: Set
        .... .... 1... = Push: Set
        .... .... .0.. = Reset: Not set
        .... .... ..0. = Syn: Not set
        .... .... ...0 = Fin: Not set
        [TCP Flags: ·······AP···]
    Window size value: 350
    [Calculated window size: 44800]
    [Window size scaling factor: 128]
    Checksum: 0xfe37 [unverified]
    [Checksum Status: Unverified]
    Urgent pointer: 0
    Options: (12 bytes), No-Operation (NOP), No-Operation (NOP), Timestamps
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - Timestamps: TSval 1764320477, TSecr 1764319312
            Kind: Time Stamp Option (8)
            Length: 10
            Timestamp value: 1764320477
            Timestamp echo reply: 1764319312
    [SEQ/ACK analysis]
        [iRTT: 0.000021000 seconds]
        [Bytes in flight: 15]
        [Bytes sent since last PSH flag: 15]
    TCP payload (15 bytes)
    [PDU Size: 15]
WebSocket
    1... .... = Fin: True
    .000 .... = Reserved: 0x0
    .... 0001 = Opcode: Text (1)
    1... .... = Mask: True
    .000 1001 = Payload length: 9
    Masking-Key: 2f0bda1c
    Masked payload
    Payload
Line-based text data
    alamakota

Frame 12: 102 bytes on wire (816 bits), 102 bytes captured (816 bits)
    Encapsulation type: Ethernet (1)
    Arrival Time: Sep 19, 2017 20:35:46.492378000 CEST
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1505846146.492378000 seconds
    [Time delta from previous captured frame: 0.000616000 seconds]
    [Time delta from previous displayed frame: 0.000616000 seconds]
    [Time since reference or first frame: 3.888254000 seconds]
    Frame Number: 12
    Frame Length: 102 bytes (816 bits)
    Capture Length: 102 bytes (816 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ethertype:ip:tcp:http:websocket]
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)
    Destination: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Source: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
    0100 .... = Version: 4
    .... 0101 = Header Length: 20 bytes (5)
    Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
        0000 00.. = Differentiated Services Codepoint: Default (0)
        .... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    Total Length: 88
    Identification: 0xd42e (54318)
    Flags: 0x02 (Don't Fragment)
        0... .... = Reserved bit: Not set
        .1.. .... = Don't fragment: Set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: TCP (6)
    Header checksum: 0x686f [validation disabled]
    [Header checksum status: Unverified]
    Source: 127.0.0.1
    Destination: 127.0.0.1
    [Source GeoIP: Unknown]
    [Destination GeoIP: Unknown]
TCP Src Port: 50000, Dst Port: 53832, Seq: 130, Ack: 240, Len: 36
    Src Port: 50000
    Dest Port: 53832
    [Stream index: 0]
    [TCP Segment Len: 36]
    Sequence number: 130    (relative sequence number)
    [Next sequence number: 166    (relative sequence number)]
    Acknowledgment number: 240    (relative ack number)
    1000 .... = Header Length: 32 bytes (8)
    Flags: 0x018 (PSH, ACK)
        000. .... .... = Reserved: Not set
        ...0 .... .... = Nonce: Not set
        .... 0... .... = Congestion Window Reduced (CWR): Not set
        .... .0.. .... = ECN-Echo: Not set
        .... ..0. .... = Urgent: Not set
        .... ...1 .... = Acknowledgment: Set
        .... .... 1... = Push: Set
        .... .... .0.. = Reset: Not set
        .... .... ..0. = Syn: Not set
        .... .... ...0 = Fin: Not set
        [TCP Flags: ·······AP···]
    Window size value: 350
    [Calculated window size: 44800]
    [Window size scaling factor: 128]
    Checksum: 0xfe4c [unverified]
    [Checksum Status: Unverified]
    Urgent pointer: 0
    Options: (12 bytes), No-Operation (NOP), No-Operation (NOP), Timestamps
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - Timestamps: TSval 1764320478, TSecr 1764320477
            Kind: Time Stamp Option (8)
            Length: 10
            Timestamp value: 1764320478
            Timestamp echo reply: 1764320477
    [SEQ/ACK analysis]
        [This is an ACK to the segment in frame: 11]
        [The RTT to ACK the segment was: 0.000616000 seconds]
        [iRTT: 0.000021000 seconds]
        [Bytes in flight: 36]
        [Bytes sent since last PSH flag: 36]
    TCP payload (36 bytes)
    [PDU Size: 36]
WebSocket
    1... .... = Fin: True
    .000 .... = Reserved: 0x0
    .... 1000 = Opcode: Connection Close (8)
    0... .... = Mask: False
    .010 0010 = Payload length: 34
    Payload
        Close
            Status code: Unsupported Data (1003)
            Reason: Unsupported: Unknown opcode 0x01

Frame 13: 66 bytes on wire (528 bits), 66 bytes captured (528 bits)
    Encapsulation type: Ethernet (1)
    Arrival Time: Sep 19, 2017 20:35:46.492394000 CEST
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1505846146.492394000 seconds
    [Time delta from previous captured frame: 0.000016000 seconds]
    [Time delta from previous displayed frame: 0.000016000 seconds]
    [Time since reference or first frame: 3.888270000 seconds]
    Frame Number: 13
    Frame Length: 66 bytes (528 bits)
    Capture Length: 66 bytes (528 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ethertype:ip:tcp]
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)
    Destination: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Source: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
    0100 .... = Version: 4
    .... 0101 = Header Length: 20 bytes (5)
    Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
        0000 00.. = Differentiated Services Codepoint: Default (0)
        .... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    Total Length: 52
    Identification: 0x1582 (5506)
    Flags: 0x02 (Don't Fragment)
        0... .... = Reserved bit: Not set
        .1.. .... = Don't fragment: Set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: TCP (6)
    Header checksum: 0x2740 [validation disabled]
    [Header checksum status: Unverified]
    Source: 127.0.0.1
    Destination: 127.0.0.1
    [Source GeoIP: Unknown]
    [Destination GeoIP: Unknown]
TCP Src Port: 53832, Dst Port: 50000, Seq: 240, Ack: 166, Len: 0
    Src Port: 53832
    Dest Port: 50000
    [Stream index: 0]
    [TCP Segment Len: 0]
    Sequence number: 240    (relative sequence number)
    Acknowledgment number: 166    (relative ack number)
    1000 .... = Header Length: 32 bytes (8)
    Flags: 0x010 (ACK)
        000. .... .... = Reserved: Not set
        ...0 .... .... = Nonce: Not set
        .... 0... .... = Congestion Window Reduced (CWR): Not set
        .... .0.. .... = ECN-Echo: Not set
        .... ..0. .... = Urgent: Not set
        .... ...1 .... = Acknowledgment: Set
        .... .... 0... = Push: Not set
        .... .... .0.. = Reset: Not set
        .... .... ..0. = Syn: Not set
        .... .... ...0 = Fin: Not set
        [TCP Flags: ·······A····]
    Window size value: 350
    [Calculated window size: 44800]
    [Window size scaling factor: 128]
    Checksum: 0xfe28 [unverified]
    [Checksum Status: Unverified]
    Urgent pointer: 0
    Options: (12 bytes), No-Operation (NOP), No-Operation (NOP), Timestamps
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - Timestamps: TSval 1764320478, TSecr 1764320478
            Kind: Time Stamp Option (8)
            Length: 10
            Timestamp value: 1764320478
            Timestamp echo reply: 1764320478
    [SEQ/ACK analysis]
        [This is an ACK to the segment in frame: 12]
        [The RTT to ACK the segment was: 0.000016000 seconds]
        [iRTT: 0.000021000 seconds]

Frame 14: 106 bytes on wire (848 bits), 106 bytes captured (848 bits)
    Encapsulation type: Ethernet (1)
    Arrival Time: Sep 19, 2017 20:35:46.494661000 CEST
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1505846146.494661000 seconds
    [Time delta from previous captured frame: 0.002267000 seconds]
    [Time delta from previous displayed frame: 0.002267000 seconds]
    [Time since reference or first frame: 3.890537000 seconds]
    Frame Number: 14
    Frame Length: 106 bytes (848 bits)
    Capture Length: 106 bytes (848 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ethertype:ip:tcp:http:websocket]
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)
    Destination: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Source: 00:00:00_00:00:00 (00:00:00:00:00:00)
        Address: 00:00:00_00:00:00 (00:00:00:00:00:00)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
    0100 .... = Version: 4
    .... 0101 = Header Length: 20 bytes (5)
    Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
        0000 00.. = Differentiated Services Codepoint: Default (0)
        .... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    Total Length: 92
    Identification: 0x1583 (5507)
    Flags: 0x02 (Don't Fragment)
        0... .... = Reserved bit: Not set
        .1.. .... = Don't fragment: Set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: TCP (6)
    Header checksum: 0x2717 [validation disabled]
    [Header checksum status: Unverified]
    Source: 127.0.0.1
    Destination: 127.0.0.1
    [Source GeoIP: Unknown]
    [Destination GeoIP: Unknown]
TCP Src Port: 53832, Dst Port: 50000, Seq: 240, Ack: 166, Len: 40
    Src Port: 53832
    Dest Port: 50000
    [Stream index: 0]
    [TCP Segment Len: 40]
    Sequence number: 240    (relative sequence number)
    [Next sequence number: 280    (relative sequence number)]
    Acknowledgment number: 166    (relative ack number)
    1000 .... = Header Length: 32 bytes (8)
    Flags: 0x018 (PSH, ACK)
        000. .... .... = Reserved: Not set
        ...0 .... .... = Nonce: Not set
        .... 0... .... = Congestion Window Reduced (CWR): Not set
        .... .0.. .... = ECN-Echo: Not set
        .... ..0. .... = Urgent: Not set
        .... ...1 .... = Acknowledgment: Set
        .... .... 1... = Push: Set
        .... .... .0.. = Reset: Not set
        .... .... ..0. = Syn: Not set
        .... .... ...0 = Fin: Not set
        [TCP Flags: ·······AP···]
    Window size value: 350
    [Calculated window size: 44800]
    [Window size scaling factor: 128]
    Checksum: 0xfe50 [unverified]
    [Checksum Status: Unverified]
    Urgent pointer: 0
    Options: (12 bytes), No-Operation (NOP), No-Operation (NOP), Timestamps
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - No-Operation (NOP)
            Kind: No-Operation (1)
        TCP Option - Timestamps: TSval 1764320478, TSecr 1764320478
            Kind: Time Stamp Option (8)
            Length: 10
            Timestamp value: 1764320478
            Timestamp echo reply: 1764320478
    [SEQ/ACK analysis]
        [iRTT: 0.000021000 seconds]
        [Bytes in flight: 40]
        [Bytes sent since last PSH flag: 40]
    TCP payload (40 bytes)
    [PDU Size: 40]
WebSocket
    1... .... = Fin: True
    .000 .... = Reserved: 0x0
    .... 1000 = Opcode: Connection Close (8)
    1... .... = Mask: True
    .010 0010 = Payload length: 34
    Masking-Key: 3daec4d6
    Masked payload
    Payload
        Close
            Status code: Unsupported Data (1003)
            Reason: Unsupported: Unknown opcode 0x01

Parece que wscat envia um código de operação (0x1) que websockify entende como 0x01 e não reconhece, mas não sei por quê.

Como faço essa configuração funcionar? Eu tentei conectar-me a websockify com programas diferentes (implementação do websocket do navegador, wscat alternatives), mas todos falharam.

    
por styrofoam fly 20.09.2017 / 18:11

1 resposta

0

Eu acertei o mesmo problema:

socket.send("hi"); // websockify chokes

... que foi corrigido por:

b = new Blob(["hi", "\n"], {type: 'text/plain'});
socket.send(b); // works as expected
    
por 06.11.2017 / 16:07

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