dms_tailscalectl/tailscalectl/lib.js

function parsePeers(peerMap) {
    if (!peerMap) return []
    return Object.keys(peerMap).map(function (key) {
        if (!Object.prototype.hasOwnProperty.call(peerMap, key)) return null
        var p = peerMap[key]
        return {
            hostname: p.HostName || key,
            ip: (p.TailscaleIPs && p.TailscaleIPs.length) ? p.TailscaleIPs[0] : "",
            online: p.Online || false,
            exitNode: p.ExitNodeOption || false
        }
    }).filter(function (peer) { return peer !== null })
}

function makeExitNodeCommand(hostname) {
    if (!isValidExitNodeHostname(hostname)) {
        return null;
    }
    if (hostname === "") {
        return ["tailscale", "set", "--exit-node="];
    }
    return ["tailscale", "set", "--exit-node=" + hostname];
}

function findActiveExitNode(peerMap) {
    if (!peerMap) return ""
    for (const key in peerMap) {
        if (!Object.prototype.hasOwnProperty.call(peerMap, key)) continue
        const p = peerMap[key]
        if (p.ExitNode) {
            return p.HostName || key
        }
    }
    return ""
}

const clipboardTools = [
    { argv: ["dms", "cl", "copy"] },
    { argv: ["wl-copy"] }
];

function getClipboardCommands(text) {
    return clipboardTools.map(function (tool) {
        return tool.argv.concat([text]);
    });
}

function getStrings() {
    return {
        header: "Tailscale",
        connected: "Connected",
        disconnected: "Disconnected",
        exitNodePrefix: "Exit node: ",
        none: "None",
        copied: function (text) { return "Copied " + text + " to clipboard" },
        clearExitNode: "×",
        setExitNode: "↗",
        invalidExitNodeHostname: "Invalid exit node hostname"
    }
}

// Light UI predicates — keep the view thin.
function shouldShowClearExitNode(currentExitNode) {
    return currentExitNode !== ""
}

function isActiveExitNode(currentExitNode, hostname) {
    return currentExitNode === hostname
}

// Security: validate hostnames coming from tailscale status JSON.
// Fail closed on obviously malicious input.
function isValidExitNodeHostname(hostname) {
    if (typeof hostname !== "string") return false;
    if (hostname === "") return true; // clear command
    // Permissive enough for real Tailscale hostnames while rejecting
    // classic shell metacharacters and control characters.
    return /^[a-zA-Z0-9]([a-zA-Z0-9-_.]{0,62}[a-zA-Z0-9])?$/.test(hostname);
}

function parseStatusResult(jsonText) {
    try {
        const data = JSON.parse(jsonText)
        return {
            isConnected: data.BackendState === "Running",
            tailscaleIP: (data.Self && data.Self.TailscaleIPs && data.Self.TailscaleIPs[0]) || "",
            currentExitNode: findActiveExitNode(data.Peer || {}),
            peers: parsePeers(data.Peer || {})
        }
    } catch (e) {
        return { isConnected: false, tailscaleIP: "", currentExitNode: "", peers: [] }
    }
}

function buildToggleCommand(isConnected) {
    return isConnected ? ["tailscale", "down"] : ["tailscale", "up"]
}

// Single source of truth for the status command used for on-demand and post-action verification.
function getStatusCommand() {
    return ["tailscale", "status", "--json"]
}

function errorMessage(cmd) {
    var messages = {
        "up": "Failed to connect to Tailscale",
        "connect": "Failed to connect to Tailscale",
        "down": "Failed to disconnect from Tailscale",
        "disconnect": "Failed to disconnect from Tailscale",
        "set": "Failed to set exit node",
        "status": "Failed to read Tailscale status",
        "clipboard": "Error copying to clipboard"
    };
    return messages[cmd] || "Tailscale command failed";
}

// Central error formatting for the widget. Used by both success and error paths.
// detail is optional truncated stderr or extra context.
function formatError(action, detail) {
    var base = errorMessage(action);
    if (detail && detail.length > 0) {
        var truncated = detail.length > 120 ? detail.slice(0, 120) : detail;
        return base + " — " + truncated;
    }
    return base;
}

const PendingAction = Object.freeze({
    TOGGLE: "toggle"
});

function commandForPendingAction(pending, freshIsConnected) {
    if (pending === PendingAction.TOGGLE) {
        return buildToggleCommand(freshIsConnected);
    }
    return null;
}

if (typeof module !== "undefined" && module.exports) {
    module.exports = { parsePeers, makeExitNodeCommand, findActiveExitNode, errorMessage, formatError, getStatusCommand, isValidExitNodeHostname, getClipboardCommands, buildToggleCommand, parseStatusResult, getStrings, shouldShowClearExitNode, isActiveExitNode, PendingAction, commandForPendingAction };
}