105 lines
3.0 KiB
JavaScript
105 lines
3.0 KiB
JavaScript
/**
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* @file pty-attach.js
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* @description Bridges one WebSocket connection to a `node-pty`-backed
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* `tmux attach-session` process. Binary WS frames carry raw PTY bytes in
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* both directions; text WS frames carry small JSON control messages
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* (`resize`, and an outbound `exit` sent once when the pane process/tmux
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* session ends). Multiple browser tabs each get their own PTY attach
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* process — tmux itself is what keeps them all in sync, this module does no
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* cross-connection coordination.
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* @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
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*/
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const RUN_ID_RE = /^ccam-lane-\d+$/;
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/**
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* Reject anything that isn't exactly `ccam-lane-<digits>` before it can ever
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* reach a tmux/PTY command — the trust boundary for this WS path, since a
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* validated runId is the only thing standing between an authenticated WS
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* client and naming an arbitrary session on the host.
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*/
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function validateRunId(runId) {
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if (typeof runId !== "string" || !RUN_ID_RE.test(runId)) {
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const err = new Error(`EBADRUNID: invalid runId: ${runId}`);
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err.code = "EBADRUNID";
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throw err;
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}
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}
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// Test seam — real implementation set in Step 4.
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let spawnImpl = null;
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function __setSpawnImpl(fn) {
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spawnImpl = fn;
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}
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/**
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* Attach `ws` to the tmux session `runId`. Spawns one PTY-backed
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* `tmux attach-session -t <runId>` per call.
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*/
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function attach(ws, runId, { cols, rows }) {
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validateRunId(runId);
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const pty = spawnImpl("tmux", ["attach-session", "-t", runId], {
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name: "xterm-256color",
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cols: cols || 80,
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rows: rows || 24,
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});
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pty.onData((data) => {
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try {
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ws.send(data, { binary: true });
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} catch {
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/* client gone between data event and send — safe to ignore */
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}
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});
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pty.onExit(({ exitCode }) => {
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try {
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ws.send(JSON.stringify({ type: "exit", code: exitCode }), { binary: false });
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} catch {
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/* ignore */
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}
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try {
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ws.close();
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} catch {
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/* ignore */
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}
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});
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ws.on("message", (data, isBinary) => {
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// node-pty attach processes for `tmux attach` are already tolerant of
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// resize mid-stream; the `ws` lib passes isBinary either as the second
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// callback arg (newer) or via `data.binary` on some transports — this
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// helper's own tests exercise the `{binary}` option shape used above.
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const binary = typeof isBinary === "boolean" ? isBinary : !!(isBinary && isBinary.binary);
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if (binary) {
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pty.write(data.toString("utf8"));
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return;
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}
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let msg;
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try {
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msg = JSON.parse(data.toString("utf8"));
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} catch {
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return;
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}
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if (msg && msg.type === "resize" && Number.isFinite(msg.cols) && Number.isFinite(msg.rows)) {
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pty.resize(msg.cols, msg.rows);
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}
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});
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ws.on("close", () => {
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try {
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pty.kill();
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} catch {
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/* already gone */
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}
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});
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return pty;
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}
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// Real spawn implementation — lazy-required so unit tests never load the
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// native node-pty addon unless they explicitly opt in.
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__setSpawnImpl((...args) => require("node-pty").spawn(...args));
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module.exports = { attach, validateRunId, __setSpawnImpl };
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