@ai-ecoverse/wasix-websocat

websocat 4.0.0-alpha3, the WebSocket client and server ("netcat for ws://"), built for slicc's kernel as a WASIX program. This is an upstream alpha: websocat v4 has no stable release yet. It's upstream's source with two WASIX patches (subprocesses fail cleanly; see below) and a patch for exit codes and logs (see Exit codes and logs). The build also patches crate wiring and the WASIX fork of mio; see the recipe.

pnpm add -g @ai-ecoverse/wasix-websocat
websocat -s 8080 mirror:                 # an echo server on the kernel loopback
echo hi | websocat ws://127.0.0.1:8080/  # hi
websocat -b ws://127.0.0.1:8080/ < file  # binary messages

Needs slicc-kernel 1.95.0 or later (WASIX epoll and eventfd, slicc-kernel#674).

Networking

websocat v4 opens its own TCP connections and does its own TLS, with rustls and the bundled Mozilla roots (webpki-roots), so wss:// needs no CA setup. It has no HTTP or SOCKS proxy support, so it never goes through the kernel's https_proxy.

• Kernel loopback (127.0.0.1, localhost) always works.
• Other hosts (ws://example.com/, wss://…) need an exit that gives programs raw TCP: in seven, a linked slicc CLI or a Tailscale exit node (the kernel's uplink). Without one:
  • a name fails with No such file or directory (os error 44);
  • an address fails with Network unreachable.
• No TLS server: websocat v4 can't serve wss://.
• What the cert covers through an uplink: ws:// echo, and wss:// with -k. That's the TLS handshake and framing against a throwaway CA. Chain verification uses the embedded webpki roots, and is covered by slicc-bios end to end.

Limits on WASIX

• No subprocesses (homescoop#689, #709): websocat's process support doesn't work on this target. exec:, cmd: and sh-c: are refused at startup (exec:, cmd: and sh-c: are not supported on WASIX), and so is --exec-after-listen. In -x scenario scripts, subprocess_new, subprocess_new_osstr and system fail with subprocesses are not supported on WASIX. Every case exits non-zero, with no panic.

Exit codes and logs

Since 4.0.0-alpha3-7, a failure that upstream v4 only logged exits non-zero, and every log line goes to stderr, so websocat … > out and websocat … | jq carry only data (homescoop#868). RUST_LOG sets the level (RUST_LOG=debug, RUST_LOG=off; default INFO, homescoop#1421):

websocat 4 is upstream's current line but still a pre-release: options and specifiers differ from websocat 1.x (see websocat --help; for example, there's no -1).