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

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

import { execFile } from "node:child_process";
import { readFile } from "node:fs/promises";
import { homedir, hostname, userInfo } from "node:os";
import path from "node:path";
import { promisify } from "node:util";
import { listMachines } from "../profile-store.js";
import { findPhrenPath } from "../phren-paths.js";
import { computerLabel } from "./hand-off.js";
import { localNames } from "./computer-names.js";
import { acceptComputer, computerName, enrollComputer, publicComputerKey } from "./computers.js";
import { addHookPeer, optionalHookPeers, peerRequest } from "./peers.js";
import { BridgeError, bridgeRoot, object } from "./protocol.js";
/**
 * Computers the owner already reaches over plain ssh that run phren, and
 * linking one in a single explicit step. Discovery only reports; nothing is
 * linked until the owner runs `phren bridge link <host>`.
 */
const exec = promisify(execFile);
// A non-login ssh shell often lacks Homebrew's node (macOS) or ~/.local/bin.
const REMOTE_PATH = 'PATH="$HOME/.local/bin:/opt/homebrew/bin:/usr/local/bin:$PATH"';
const GIT_HOSTS = /(^|\.)(github\.com|gitlab\.com|bitbucket\.org)$/i;
/** Concrete Host aliases from an ssh config: no patterns, no Git hosting services. */
export function sshConfigHosts(text) {
    const hosts = [];
    let block = [], skip = false;
    const flush = () => { if (!skip)
        hosts.push(...block); block = []; skip = false; };
    for (const raw of text.split(/\r?\n/)) {
        const match = /^\s*([A-Za-z]+)(?:\s*=\s*|\s+)(.+?)\s*$/.exec(raw.replace(/\s#.*$|^\s*#.*$/, ""));
        if (!match)
            continue;
        const [key, value] = [match[1].toLowerCase(), match[2]];
        if (key === "host" || key === "match") {
            flush();
            if (key === "host")
                block = value.split(/\s+/).filter(alias => !/[*?!]/.test(alias));
        }
        else if (key === "hostname" && GIT_HOSTS.test(value))
            skip = true;
    }
    flush();
    return [...new Set(hosts.filter(alias => !GIT_HOSTS.test(alias)))];
}
async function ssh(host, command, input, timeout = 20_000) {
    return new Promise((resolve, reject) => {
        const child = execFile("ssh", ["-o", "BatchMode=yes", "-o", "ConnectTimeout=5", "--", host, command], { timeout, maxBuffer: 1_048_576 }, (error, stdout, stderr) => {
            if (error)
                reject(new BridgeError(503, `ssh ${host}: ${(stderr || error.message).split("\n").find(Boolean)?.slice(0, 200) ?? "failed"}`));
            else
                resolve(stdout);
        });
        child.stdin?.end(input ?? "");
    });
}
/** What a host reports over the owner's own ssh login: its Hook's computer id
 * (present once Phren Hook is installed), login user and this computer's
 * address as that host sees it. */
async function probe(host) {
    const out = await ssh(host, `printf 'id=%s\\nuser=%s\\nclient=%s\\n' "$(cat ~/.local/share/phren/bridge/computer-id 2>/dev/null)" "$(id -un)" "\${SSH_CONNECTION%% *}"`, undefined, 12_000);
    const field = (name) => new RegExp(`^${name}=(.*)$`, "m").exec(out)?.[1]?.trim() || undefined;
    const computerId = field("id");
    return computerId ? { host, computerId, user: field("user") ?? "", client: field("client") } : undefined;
}
/** Hosts from ~/.ssh/config and the store's machines.yaml that answer over ssh,
 * run Phren Hook and are not this computer or an already linked peer. */
export async function discoverComputers(options = {}) {
    const config = options.sshConfig ?? await readFile(path.join(homedir(), ".ssh", "config"), "utf8").catch(() => "");
    const store = options.store !== undefined ? options.store : findPhrenPath();
    const machines = store ? listMachines(store) : undefined;
    const { peers } = await optionalHookPeers();
    const own = (await readFile(path.join(bridgeRoot(), "computer-id"), "utf8").catch(() => "")).trim();
    const known = new Set([...localNames(), ...peers.flatMap(peer => [peer.name, peer.address])].map(computerLabel));
    const candidates = [...new Set([...sshConfigHosts(config), ...(machines?.ok ? Object.keys(machines.data) : [])])]
        .filter(host => !known.has(computerLabel(host))).slice(0, 32);
    // A linked peer registered under another name is still linked: match it by its Hook's computer id.
    const [found, peerIds] = await Promise.all([
        Promise.all(candidates.map(host => probe(host).catch(() => undefined))),
        Promise.all(peers.map(peer => peerRequest(peer, "/v1/health").then(health => object(health.computer).id, () => undefined))),
    ]);
    const seen = new Set([own, ...peerIds.filter((id) => typeof id === "string")]);
    const reachable = found.filter((item) => {
        if (!item || seen.has(item.computerId))
            return false;
        seen.add(item.computerId);
        return true;
    });
    return { reachable, checked: candidates };
}
function slugName(value) {
    const label = computerLabel(value).replace(/[^A-Za-z0-9_.-]+/g, "-").replace(/^[^A-Za-z0-9_]+/, "") || "computer";
    return computerName.parse(label.slice(0, 100));
}
/**
 * Links this computer and `host` in both directions over the owner's existing
 * ssh login: each side's dispatch key is enrolled on the other, and each
 * side's ed25519 host key is read over that login (never keyscanned) and
 * pinned in the other's hooks.yaml. Both sides then check the link.
 */
export async function linkComputer(host, options = {}) {
    const remote = await probe(host);
    if (!remote)
        throw new BridgeError(409, `${host} answers over ssh but Phren Hook is not installed there. Run phren bridge install on it first.`);
    const own = (await readFile(path.join(bridgeRoot(), "computer-id"), "utf8").catch(() => "")).trim();
    if (remote.computerId === own)
        throw new BridgeError(409, `${host} is this computer.`);
    const name = computerName.parse(options.name ?? slugName(host));
    const as = computerName.parse(options.as ?? slugName(hostname()));
    const backAddress = options.backAddress ?? remote.client;
    if (!backAddress)
        throw new BridgeError(409, `${host} did not report this computer's address; pass --back-address.`);
    // The address the Hook dials skips ~/.ssh/config, so resolve the alias the way ssh does.
    const resolved = Object.fromEntries((await exec("ssh", ["-G", "--", host], { timeout: 5_000 })).stdout.split("\n")
        .map(line => line.split(" ")).filter(parts => parts.length >= 2).map(([key, ...rest]) => [key, rest.join(" ")]));
    const remoteHostKey = publicComputerKey((await ssh(host, "cat /etc/ssh/ssh_host_ed25519_key.pub")).trim().split(/\s+/).slice(0, 2).join(" "));
    const localHostKey = publicComputerKey((await readFile("/etc/ssh/ssh_host_ed25519_key.pub", "utf8")).trim().split(/\s+/).slice(0, 2).join(" "));
    const remoteLine = (await ssh(host, `${REMOTE_PATH} phren bridge enroll-computer ${name}`)).trim();
    await ssh(host, `f=$(mktemp) && cat > "$f" && ${REMOTE_PATH} phren bridge enroll-computer ${as} --accept "$f"; s=$?; rm -f "$f"; exit $s`, await enrollComputer(as));
    await acceptComputer(name, remoteLine);
    const peer = { name, address: String(resolved.hostname || host), username: remote.user || String(resolved.user), port: Number(resolved.port) || 22, server: "default", hostKey: remoteHostKey };
    const local = await addHookPeer(peer);
    const back = { name: as, address: backAddress, username: userInfo().username, port: 22, server: "default", hostKey: localHostKey };
    const answer = JSON.parse(await ssh(host, `${REMOTE_PATH} phren bridge add-peer`, JSON.stringify(back), 45_000).catch((error) => {
        if (/Usage: phren bridge/.test(error.message))
            throw new BridgeError(409, `phren on ${host} is too old to finish linking. Update it there and run this again; the keys already exchanged are reused.`);
        throw error;
    }));
    const reached = await peerRequest(peer, "/v1/health").then(() => undefined, (error) => error.message);
    return { name, as, local: { added: local.added }, remote: { added: !!answer.added, reachable: !!answer.reachable, ...(answer.error ? { error: String(answer.error) } : {}) },
        reachable: !reached, ...(reached ? { error: reached } : {}) };
}
/** The receiving half of a link: pin the caller in hooks.yaml, then dial it back. */
export async function addPeerFromLink(input) {
    const { added, peer } = await addHookPeer(JSON.parse(input));
    const error = await peerRequest(peer, "/v1/health").then(() => undefined, (failure) => failure.message);
    return { added, reachable: !error, ...(error ? { error } : {}) };
}