websocat: I/O failure when trying to talk to `localhost`

When I try to connect to localhost, I get this error, but when I use 127.0.0.1 instead, everything is fine. I guess websocat can’t resolve names or something? curl can talk to the server running on localhost just fine. Would be cool to have this fixed for ease of use. And thank you for the tool, it does seem to work quite well otherwise 👍

E.g.:

user@hostname $ websocat ws://localhost:8080/ws
websocat: WebSocketError: I/O failure
websocat: error running

user@hostname $ websocat ws://127.0.0.1:8080/ws
# no error

user@hostname $ curl localhost:8080/ws
# no error

About this issue

Original URL
State: closed
Created 6 years ago
Reactions: 18
Comments: 24 (11 by maintainers)

Commits related to this issue

Fix Happy Eyeballs for "tcp:" specifier. Now if one of resolved addresses fails and other connects, we do connect instead of erroring out early. Partially addresses #23. — committed to vi/websocat by vi 2 years ago
consul: use 127.0.0.1 instead of localhost Otherwise it fails with: ``` websocat: WebSocketError: I/O failure websocat: error running ``` https://github.com/vi/websocat/issues/23 Signed-off-by: Jaku... — committed to status-im/infra-role-nim-waku by jakubgs 2 years ago
Implement Happy Eyeballs for ws:// Resolves #23. Resolves #194. — committed to sthagen/vi-websocat by vi 3 months ago

Most upvoted comments

Thank you for making websocat. It’s a great tool that has helped me a lot.

If you haven’t already, I suggest you indicate its current “localhost” connection limitation relatively prominently in the documentation. Perhaps in the “limitations” section at the bottom of the current README.md file? It’s trivial to work around if you know about it. It can be a scare-inducing trap for the unwary if you don’t. Asking for a friend.

TrueGit on Jul 4, 2023

Websocat 2.0 is going to have Happy Eyeballs and try to connect to both, whichever is faster.

vi on Oct 23, 2019

I think I know what happened there. localhost has been resolved to two addresses - v6 and v4. websocat tried to connect to v6, got rejected and didn’t try v4.

By the way, I’m using macOS in case that matters.

pshirshov on Oct 23, 2019

I have the same issue on macOS:

❯ websocat -vvv ws://localhost:8081/ws
[INFO  websocat::lints] Auto-inserting the line mode
[DEBUG websocat] Done third phase of interpreting options.
[DEBUG websocat] Done fourth phase of interpreting options.
[DEBUG websocat] Preparation done. Now actually starting.
[INFO  websocat::sessionserve] Serving Line2Message(Stdio) to Message2Line(WsClient("ws://localhost:8081/ws")) with Options { websocket_text_mode: true, websocket_protocol: None, websocket_reply_protocol: None, udp_oneshot_mode: false, unidirectional: false, unidirectional_reverse: false, exit_on_eof: false, oneshot: false, unlink_unix_socket: 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, one_message: false, no_auto_linemode: false, buffer_size: 65536, broadcast_queue_len: 16, read_debt_handling: Warn, linemode_zero_terminated: false, restrict_uri: None, serve_static_files: [], exec_set_env: 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 }
[INFO  websocat::stdio_peer] get_stdio_peer (async)
[INFO  websocat::stdio_peer] Setting stdin to nonblocking mode
[INFO  websocat::stdio_peer] Installing signal handler
[DEBUG websocat::sessionserve] Underlying connection established
[INFO  websocat::ws_client_peer] get_ws_client_peer
[DEBUG websocat::stdio_peer] restore_blocking_status
[INFO  websocat::stdio_peer] Restoring blocking status for stdin
websocat: WebSocketError: I/O failure
[DEBUG websocat::stdio_peer] restore_blocking_status
[INFO  websocat::stdio_peer] Restoring blocking status for stdin
websocat: error running

Wrong port:

❯ websocat -vvv ws://localhost:32121/ws
[INFO  websocat::lints] Auto-inserting the line mode
[DEBUG websocat] Done third phase of interpreting options.
[DEBUG websocat] Done fourth phase of interpreting options.
[DEBUG websocat] Preparation done. Now actually starting.
[INFO  websocat::sessionserve] Serving Line2Message(Stdio) to Message2Line(WsClient("ws://localhost:32121/ws")) with Options { websocket_text_mode: true, websocket_protocol: None, websocket_reply_protocol: None, udp_oneshot_mode: false, unidirectional: false, unidirectional_reverse: false, exit_on_eof: false, oneshot: false, unlink_unix_socket: 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, one_message: false, no_auto_linemode: false, buffer_size: 65536, broadcast_queue_len: 16, read_debt_handling: Warn, linemode_zero_terminated: false, restrict_uri: None, serve_static_files: [], exec_set_env: 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 }
[INFO  websocat::stdio_peer] get_stdio_peer (async)
[INFO  websocat::stdio_peer] Setting stdin to nonblocking mode
[INFO  websocat::stdio_peer] Installing signal handler
[DEBUG websocat::sessionserve] Underlying connection established
[INFO  websocat::ws_client_peer] get_ws_client_peer
[DEBUG websocat::stdio_peer] restore_blocking_status
[INFO  websocat::stdio_peer] Restoring blocking status for stdin
websocat: WebSocketError: I/O failure
[DEBUG websocat::stdio_peer] restore_blocking_status
[INFO  websocat::stdio_peer] Restoring blocking status for stdin
websocat: error running

IP Address:

❯ websocat -vvv ws://127.0.0.1:8080/ws
[INFO  websocat::lints] Auto-inserting the line mode
[DEBUG websocat] Done third phase of interpreting options.
[DEBUG websocat] Done fourth phase of interpreting options.
[DEBUG websocat] Preparation done. Now actually starting.
[INFO  websocat::sessionserve] Serving Line2Message(Stdio) to Message2Line(WsClient("ws://127.0.0.1:8080/ws")) with Options { websocket_text_mode: true, websocket_protocol: None, websocket_reply_protocol: None, udp_oneshot_mode: false, unidirectional: false, unidirectional_reverse: false, exit_on_eof: false, oneshot: false, unlink_unix_socket: 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, one_message: false, no_auto_linemode: false, buffer_size: 65536, broadcast_queue_len: 16, read_debt_handling: Warn, linemode_zero_terminated: false, restrict_uri: None, serve_static_files: [], exec_set_env: 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 }
[INFO  websocat::stdio_peer] get_stdio_peer (async)
[INFO  websocat::stdio_peer] Setting stdin to nonblocking mode
[INFO  websocat::stdio_peer] Installing signal handler
[DEBUG websocat::sessionserve] Underlying connection established
[INFO  websocat::ws_client_peer] get_ws_client_peer
[INFO  websocat::ws_client_peer] Connected to ws
fasd
[DEBUG websocat::ws_peer] incoming text
xxx
fsad
[DEBUG websocat::ws_peer] incoming text
xxx
fasd
[DEBUG websocat::ws_peer] incoming text
xxx
^C[DEBUG websocat::stdio_peer] restore_blocking_status
[INFO  websocat::stdio_peer] Restoring blocking status for stdin

At the same time I can connect without an issue to non-localhost servers:

❯ websocat -vvv ws://echo.websocket.org/
[INFO  websocat::lints] Auto-inserting the line mode
[DEBUG websocat] Done third phase of interpreting options.
[DEBUG websocat] Done fourth phase of interpreting options.
[DEBUG websocat] Preparation done. Now actually starting.
[INFO  websocat::sessionserve] Serving Line2Message(Stdio) to Message2Line(WsClient("ws://echo.websocket.org/")) with Options { websocket_text_mode: true, websocket_protocol: None, websocket_reply_protocol: None, udp_oneshot_mode: false, unidirectional: false, unidirectional_reverse: false, exit_on_eof: false, oneshot: false, unlink_unix_socket: 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, one_message: false, no_auto_linemode: false, buffer_size: 65536, broadcast_queue_len: 16, read_debt_handling: Warn, linemode_zero_terminated: false, restrict_uri: None, serve_static_files: [], exec_set_env: 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 }
[INFO  websocat::stdio_peer] get_stdio_peer (async)
[INFO  websocat::stdio_peer] Setting stdin to nonblocking mode
[INFO  websocat::stdio_peer] Installing signal handler
[DEBUG websocat::sessionserve] Underlying connection established
[INFO  websocat::ws_client_peer] get_ws_client_peer
[INFO  websocat::ws_client_peer] Connected to ws

Though curl works:

❯ curl -v http://localhost:8080/http
*   Trying ::1...
* TCP_NODELAY set
* Connection failed
* connect to ::1 port 8080 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /http HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.64.1
> Accept: */*
>
< HTTP/1.1 200 OK
< Connection: keep-alive
< Content-Type: text/plain
< Content-Length: 11
< Date: Tue, 22 Oct 2019 15:38:00 GMT
<
* Connection #0 to host localhost left intact
Hello World* Closing connection 0

❯ curl -v http://localhost:8080/ws
*   Trying ::1...
* TCP_NODELAY set
* Connection failed
* connect to ::1 port 8080 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /ws HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.64.1
> Accept: */*
>
< HTTP/1.1 404 Not Found
< Connection: keep-alive
< Content-Length: 0
< Date: Tue, 22 Oct 2019 15:38:12 GMT
<
* Connection #0 to host localhost left intact
* Closing connection 0

pshirshov on Oct 22, 2019

It tries connecting to IPv6, make sure it is also being listened on server side.

You can use websocat as a websocket server as well. IPv4: websocat -s 127.0.0.1:8080, IPv6: websocat -s [::1]:8080. Does it connect to such servers using ws://localhost:8080/?

vi on Dec 19, 2018