@phren/cli/dist/bridge/pair.js

Knowledge layer for AI agents - CLI, MCP server, and data layer

import { execFile } from "node:child_process";
import { createHash, createHmac, randomInt, timingSafeEqual } from "node:crypto";
import { lstat, readFile } from "node:fs/promises";
import { createServer } from "node:http";
import { connect } from "node:net";
import { homedir, hostname, networkInterfaces, userInfo } from "node:os";
import path from "node:path";
import { promisify } from "node:util";
import { z } from "zod";
import { appendAuthorizedKey, publicComputerKey } from "./computers.js";
import { forcedCommand, install } from "./install.js";
import { BridgeError, bridgeRoot } from "./protocol.js";
// `phren pair` connects a phone in one scan. The QR code carries where to
// reach this computer, its SSH host key fingerprint and a one-time code. The
// phone makes its own key and posts the public half here with an HMAC keyed
// by the code, so the code itself never crosses the network; this computer
// answers with an HMAC over its fingerprint, which lets a phone that typed
// the code by hand trust the host key too. One success, five bad proofs or
// the time limit closes the listener.
const exec = promisify(execFile);
export const PAIR_PORT = 47291;
const ALPHABET = "ABCDEFGHJKMNPQRSTUVWXYZ23456789";
const MAX_FAILURES = 5;
export function newPairingCode() {
    return Array.from({ length: 6 }, () => ALPHABET[randomInt(ALPHABET.length)]).join("");
}
/** Codes are typed as ABC-234 or abc234; both mean the same code. */
export function normalizeCode(code) {
    return code.toUpperCase().replace(/[^A-Z0-9]/g, "");
}
export function pairingProof(code, label, ...parts) {
    return createHmac("sha256", `phren-pair-v1:${normalizeCode(code)}`).update([label, ...parts].join("\n")).digest("base64url");
}
function sameProof(expected, received) {
    const a = Buffer.from(expected), b = Buffer.from(received);
    return a.length === b.length && timingSafeEqual(a, b);
}
/** OpenSSH's SHA256 fingerprint of a public key line, as the phone computes it. */
export function keyFingerprint(publicKeyLine) {
    const blob = publicKeyLine.trim().split(/\s+/)[1];
    if (!blob)
        return undefined;
    return "SHA256:" + createHash("sha256").update(Buffer.from(blob, "base64")).digest("base64").replace(/=+$/, "");
}
export async function hostFingerprint(file = "/etc/ssh/ssh_host_ed25519_key.pub") {
    return keyFingerprint(await readFile(file, "utf8").catch(() => ""));
}
/** Addresses the phone can try, best first: Tailscale name and address, then LAN IPv4. */
export async function pairingHosts() {
    const hosts = [];
    for (const binary of ["tailscale", "/Applications/Tailscale.app/Contents/MacOS/Tailscale"]) {
        try {
            const { stdout } = await exec(binary, ["status", "--json", "--peers=false"], { timeout: 3000, maxBuffer: 4 * 1024 * 1024 });
            const self = JSON.parse(stdout).Self;
            if (self?.DNSName)
                hosts.push(self.DNSName.replace(/\.$/, ""));
            const ipv4 = self?.TailscaleIPs?.find(ip => /^\d+\.\d+\.\d+\.\d+$/.test(ip));
            if (ipv4)
                hosts.push(ipv4);
            break;
        }
        catch { /* not installed here */ }
    }
    for (const entries of Object.values(networkInterfaces())) {
        for (const entry of entries ?? []) {
            if (entry.family === "IPv4" && !entry.internal && !hosts.includes(entry.address))
                hosts.push(entry.address);
        }
    }
    return hosts.slice(0, 5);
}
/** The name people call this computer: macOS's Computer Name, else the host name. */
export async function computerDisplayName() {
    if (process.platform === "darwin") {
        const name = await exec("scutil", ["--get", "ComputerName"], { timeout: 2000 }).then(({ stdout }) => stdout.trim()).catch(() => "");
        if (name)
            return name.slice(0, 64);
    }
    return hostname().replace(/\.local$/i, "").split(".")[0] || "Computer";
}
/** The QR payload; the phone opens phren://pair links from the camera too. */
export function pairingURL(offer) {
    const query = new URLSearchParams({ v: "1", h: offer.hosts.join(","), p: String(offer.port), u: offer.user,
        s: String(offer.sshPort), c: offer.code, n: offer.name });
    if (offer.fingerprint)
        query.set("fp", offer.fingerprint);
    return `phren://pair?${query.toString()}`;
}
const request = z.object({
    v: z.literal(1), publicKey: z.string().max(512), proof: z.string().max(128),
    device: z.enum(["ios", "android"]).default("ios"), name: z.string().max(80).optional(),
});
/** Listen for one phone. Resolves once its key is authorized; rejects on timeout or too many bad proofs. */
export async function startPairing(options) {
    let failures = 0, finished = false, timer;
    let resolve, reject;
    const done = new Promise((yes, no) => { resolve = yes; reject = no; });
    const server = createServer((incoming, response) => { void handle(incoming, response); });
    const finish = (error, paired) => {
        if (finished)
            return;
        finished = true;
        clearTimeout(timer);
        server.close();
        if (error)
            reject(error);
        else
            resolve(paired);
    };
    const reply = (response, status, body) => {
        response.writeHead(status, { "Content-Type": "application/json", "Cache-Control": "no-store" });
        response.end(JSON.stringify(body));
    };
    async function handle(incoming, response) {
        try {
            if (finished)
                throw new BridgeError(410, "Pairing is closed. Run phren pair again.");
            if (incoming.method !== "POST" || incoming.url !== "/v1/pair")
                throw new BridgeError(404, "Not found.");
            let size = 0;
            const chunks = [];
            for await (const chunk of incoming) {
                size += chunk.length;
                if (size > 4096)
                    throw new BridgeError(413, "Request is too large.");
                chunks.push(chunk);
            }
            const input = request.parse(JSON.parse(Buffer.concat(chunks).toString() || "{}"));
            const publicKey = publicComputerKey(input.publicKey);
            if (!sameProof(pairingProof(options.code, "phone", publicKey), input.proof)) {
                failures++;
                if (failures >= MAX_FAILURES)
                    setImmediate(() => finish(new Error("Too many wrong pairing codes; pairing closed. Run phren pair again.")));
                throw new BridgeError(403, "That pairing code doesn't match this computer.");
            }
            const comment = input.device === "android" ? "phren-android" : "phren-iphone";
            const encoded = publicKey.split(" ")[1];
            await appendAuthorizedKey(`restrict,pty,${forcedCommand} ${publicKey} ${comment}`, existing => existing.split(/\s+/).includes(encoded), "This phone key is already authorized with different options.", options.sshDirectory);
            reply(response, 200, {
                v: 1, name: options.name, user: options.user, sshPort: options.sshPort, fingerprint: options.fingerprint ?? null,
                proof: pairingProof(options.code, "computer", options.fingerprint ?? "", publicKey),
            });
            setImmediate(() => finish(undefined, { device: input.device, name: input.name, publicKey }));
        }
        catch (error) {
            const status = error instanceof BridgeError ? error.status : error instanceof z.ZodError || error instanceof SyntaxError ? 400 : 500;
            reply(response, status, { error: error instanceof z.ZodError ? "Invalid pairing request." : error.message });
        }
    }
    const listen = (port) => new Promise((ok, fail) => {
        server.once("error", fail);
        server.listen(port, () => { server.off("error", fail); ok(server.address().port); });
    });
    let port;
    try {
        port = await listen(options.port ?? PAIR_PORT);
    }
    catch (error) {
        if (error.code !== "EADDRINUSE" || options.port === 0)
            throw error;
        port = await listen(0);
    }
    timer = setTimeout(() => finish(new Error("Pairing timed out. Run phren pair again.")), options.timeoutMs ?? 5 * 60_000);
    return { port, done, close: () => finish(new Error("Pairing cancelled.")) };
}
async function sshListening(port) {
    return new Promise(ok => {
        const socket = connect({ host: "127.0.0.1", port, timeout: 1500 });
        socket.once("connect", () => { socket.destroy(); ok(true); });
        socket.once("timeout", () => { socket.destroy(); ok(false); });
        socket.once("error", () => ok(false));
    });
}
function sshHint() {
    return process.platform === "darwin"
        ? "Turn on Remote Login: System Settings → General → Sharing → Remote Login."
        : "Start the SSH server, for example: sudo systemctl enable --now sshd";
}
export const PAIR_USAGE = "phren pair [--minutes <1-30>] [--port <n>] [--no-install]";
export async function runPair(args, version) {
    let minutes = 5, port, installHook = true;
    for (let i = 0; i < args.length; i++) {
        if (args[i] === "--minutes" && args[i + 1])
            minutes = Number(args[++i]);
        else if (args[i] === "--port" && args[i + 1])
            port = Number(args[++i]);
        else if (args[i] === "--no-install")
            installHook = false;
        else {
            console.error(`Usage: ${PAIR_USAGE}`);
            return 1;
        }
    }
    if (!Number.isInteger(minutes) || minutes < 1 || minutes > 30 || (port !== undefined && (!Number.isInteger(port) || port < 0 || port > 65535))) {
        console.error(`Usage: ${PAIR_USAGE}`);
        return 1;
    }
    if (!["darwin", "linux"].includes(process.platform)) {
        console.error("Phone pairing supports macOS and Linux.");
        return 1;
    }
    if (installHook && !await lstat(path.join(bridgeRoot(), "installed.json")).catch(() => undefined)) {
        console.log("Installing Phren Hook, which your phone talks to…");
        await install(version);
    }
    const sshPort = 22;
    if (!await sshListening(sshPort))
        console.log(`\n⚠ SSH isn't answering on this computer. ${sshHint()}\n  Pairing can finish now; the phone connects once SSH is on.`);
    const code = newPairingCode();
    const name = await computerDisplayName(), user = userInfo().username, fingerprint = await hostFingerprint();
    const hosts = await pairingHosts();
    if (!hosts.length) {
        console.error("No network address found. Connect to Wi-Fi or Tailscale and try again.");
        return 1;
    }
    const session = await startPairing({ code, user, sshPort, fingerprint, name, port, timeoutMs: minutes * 60_000 });
    const url = pairingURL({ hosts, port: session.port, user, sshPort, fingerprint, code, name });
    const { renderUnicodeCompact } = await import("uqr");
    console.log(`\nConnect your phone to ${name}`);
    console.log("  In the Phren app: Agents → Add computer → Scan pairing code\n");
    console.log(renderUnicodeCompact(url, { border: 2 }));
    const typed = `${code.slice(0, 3)}-${code.slice(3)}`;
    console.log(`\n  Can't scan? Choose "Enter code" and type:  ${hosts[0]}${session.port === PAIR_PORT ? "" : `:${session.port}`}   ${typed}`);
    console.log(`  Waiting for your phone (${minutes} min). Ctrl-C cancels.`);
    const cancel = () => session.close();
    process.once("SIGINT", cancel);
    try {
        const paired = await session.done;
        console.log(`\n✓ Paired ${paired.name ?? "your phone"}. It can reach Phren Hook on ${name} as ${user}.`);
        console.log(`  To revoke it later, remove its ${paired.device === "android" ? "phren-android" : "phren-iphone"} line from ${path.join(homedir(), ".ssh/authorized_keys")}.`);
        return 0;
    }
    catch (error) {
        console.error(`\n${error.message}`);
        return 1;
    }
    finally {
        process.off("SIGINT", cancel);
    }
}