"Advanced" mode does not proxy connections (upgrade failed)

[Alexander--]

I am trying to get websocat to proxy my Websocket connection to another Websocket server:

$ websocat -vvvv -E --binary --pkcs12-der ~/combined.pfx  'wss-listen:192.168.1.34:49234' 'wss://example.com/ws/connection/websocket'
websocat: Unfortunately, serving multiple clients without --exit-on-eof (-E) or with -U option is prone to socket leak in this websocat version
[DEBUG websocat] Done third phase of interpreting options.
[DEBUG websocat] Done fourth phase of interpreting options.
[DEBUG websocat] Preparation done. Now actually starting.
[DEBUG websocat::sessionserve] Serving WsServer(TlsAccept(TcpListen(192.168.1.181:49234))) to WsClient("wss://example.com/ws/connection/websocket") with Options { websocket_text_mode: false, websocket_protocol: None, websocket_reply_protocol: None, udp_oneshot_mode: false, udp_broadcast: false, udp_multicast_loop: false, udp_ttl: None, udp_join_multicast_addr: [], udp_join_multicast_iface_v4: [], udp_join_multicast_iface_v6: [], udp_reuseaddr: false, unidirectional: false, unidirectional_reverse: false, max_messages: None, max_messages_rev: None, exit_on_eof: false, oneshot: false, unlink_unix_socket: false, unix_socket_accept_from_fd: false, exec_args: [], ws_c_uri: "ws://0.0.0.0/", linemode_strip_newlines: false, linemode_strict: false, origin: None, custom_headers: [], custom_reply_headers: [], websocket_version: None, websocket_dont_close: false, websocket_ignore_zeromsg: false, one_message: false, no_auto_linemode: false, buffer_size: 65536, broadcast_queue_len: 16, read_debt_handling: Silent, linemode_zero_terminated: false, restrict_uri: None, serve_static_files: [], exec_set_env: false, no_exit_on_zeromsg: false, reuser_send_zero_msg_on_disconnect: false, process_zero_sighup: false, process_exit_sighup: false, socks_destination: None, auto_socks5: None, socks5_bind_script: None, tls_domain: None, tls_insecure: false, headers_to_env: [], max_parallel_conns: None, ws_ping_interval: None, ws_ping_timeout: None, request_uri: None, request_method: None, request_headers: [], autoreconnect_delay_millis: 20, ws_text_prefix: None, ws_binary_prefix: None, ws_binary_base64: false, ws_text_base64: false, close_status_code: None, close_reason: None, asyncstdio: false, foreachmsg_wait_reads: false, announce_listens: false, timestamp_monotonic: false, print_ping_rtts: false, byte_to_exit_on: 28, max_ws_message_length: 209715200, max_ws_frame_length: 104857600, preamble: [], preamble_reverse: [], compress_deflate: false, compress_zlib: false, compress_gzip: false, uncompress_deflate: false, uncompress_zlib: false, uncompress_gzip: false }
[DEBUG websocat::net_peer] Listening TCP socket
[INFO  websocat::net_peer] Incoming TCP connection from Some(192.168.1.163:35766)
[DEBUG websocat::sessionserve] Underlying connection established
[INFO  websocat::sessionserve] Serving 1 ongoing connections
[DEBUG websocat::ssl_peer] Accepting a TLS connection
[INFO  websocat::ssl_peer] Accepted TLS connection
[DEBUG websocat::ssl_peer]   no identity certificate from the client. But Websocat may have failed to request it.
[DEBUG websocat::readdebt] Fullfulling the debt of 135 bytes
[DEBUG websocat::trivial_peer] LiteralPeer debt
[DEBUG websocat::trivial_peer] LiteralPeer finished
[DEBUG websocat::my_copy] zero len
[DEBUG websocat::my_copy] read_done
[DEBUG websocat::my_copy] done
websocat: WebSocketError: I/O failure

On the client I am receiving 400 response code and the following message:

Only WebSocket connections are welcome here

From the brief glance at the source code, it looks like websocat somehow tries to treat the connection as HTTP (??) instead of Websocket. I don't have this issue with other Websocket server software (including Golang/Gorilla and python-websockets).

I am using websocat 1.11.0 from Arch Linux repositories.

[vi]

HTTP (??) instead of Websocket

WebSocket typically starts with a HTTP upgrade. What does the client send to Websocat?

You can try to log it with something like this:

websocat  -E --binary --pkcs12-der ~/combined.pfx   ws-upgrade:log:tls-accept:tcp-listen:192.168.1.34:49234 'wss://example.com/ws/connection/websocket'

This should produce additional debugging output like this:

READ 153 "GET / HTTP/1.1\r\nHost: 127.0.0.1:1234\r\nConnection: Upgrade\r\nUpgrade: websocket\r\nSec-WebSocket-Version: 13\r\nSec-WebSocket-Key: 1+GnaZ3/ZsNl7ETXCD8L+Q==\r\n\r\n"
WRITE 129 "HTTP/1.1 101 Switching Protocols\r\nSec-WebSocket-Accept: CcUcKFF2hwqCoDKTE9Yrvjv1jiQ=\r\nConnection: Upgrade\r\nUpgrade: websocket\r\n\r\n"
READ 10 "\x81\x84\x03l\xbd*p\x08\xdb "
WRITE 6 "\x82\x04sdf\n"
READ 13 "\x81\x87\xbe\x87d\x11\xcd\xe3\x02u\xcd\xe1n"
WRITE 9 "\x82\x07sdfdsf\n"
READ 0 ""