Muszę użyć websockifyjako proxy. Ostateczna konfiguracja będzie:
- gniazdo sieciowe na stronie łączy się z
websockifyserwerem na tym samym komputerze websockifyserwer inicjuje połączenie z programem gniazda TCP nasłuchującym gdzie indziej (w tym przypadku na tym samym komputerze)- Gniazdo TCP odbiera informacje, wykonuje obliczenia, odpowiada
websockify websockifyotrzymuje odpowiedź i wysyła informacje do gniazda na stronie internetowej- odpowiedź jest prezentowana w przeglądarce użytkownika
Jednak z jakiegoś powodu websockifyodmawia przekazania informacji dalej i otrzymuje komunikat FIN wcześniej niż oczekiwano. Websockify mówi „Nieobsługiwany: nieznany kod operacji 0x01”.
Aby zbadać ten przypadek, stworzyłem MWE i przechwyciłem ruch tcpdump.
Konfiguracja jest następująca:
Po pierwsze, uruchamiam
netcat -v -v -l -p 40000- to aplikacja, do której chcemy otrzymywać informacjePotem biegnę
websockify --verbose 50000 localhost:40000- to polecenie zastępczeWreszcie uruchamiam
wscat -c localhost:50000- to aplikacja nawiązująca połączenie typu websocket zwebsockifyserwerem proxy
Gdy tylko coś wyślę wscat, wscatpołączenie jest przerywane z kodem 1003. Cytując RFC 6455 :
1003 wskazuje, że punkt końcowy kończy połączenie, ponieważ otrzymał typ danych, których nie może zaakceptować (np. Punkt końcowy, który rozumie tylko dane tekstowe, MOŻE wysłać to, jeśli otrzyma komunikat binarny).
Oto wizualna reprezentacja tego ustawienia (komunikat o błędzie „rozłączono, ponieważ zamknięty 1003” jest zapisany w ten sposób, ponieważ ręcznie zmieniłem źródło, aby wyodrębnić więcej informacji o rozłączeniu):
Oto reprezentacja danych przez Wireshark:
a oto pakiety o numerach 11,12,13 i 14, które przykuły moją uwagę:
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
Wygląda na to, że wscatwysyła kod operacyjny (0x1), który websockifyrozumie się jako 0x01 i nie rozpoznaje, ale nie wiem dlaczego.
Jak sprawić, by ta konfiguracja działała? Próbowałem nawiązać połączenie websockifyz różnymi programami (implementacja przeglądarki websocket, wscatalternatywy), ale wszystkie one zawodzą.