tiletopia/src-tauri/src/mcp.rs
megaproxy 9ebb3e4d2e MCP v2 PR-4: add_host + delete_host + extraArgs sanitiser + third SSH safeguard
Final v2 PR. All 11 planned write tools live. add_host/delete_host let
Claude mutate the saved-hosts list; both gated by a new allowAddHost
switch (default off) — symmetric with the allowOpenSsh gate from PR-3.5.

add_host's extraArgs are sanitised against CVE-2023-51385-class
local-RCE primitives: ProxyCommand, LocalCommand, KnownHostsCommand,
PermitLocalCommand=yes are refused server-side. Recognises both -o KEY=VAL
and -oKEY=VAL, case-insensitive on the key. The manual host manager UI
stays unrestricted (user has full agency over their own hosts).

Also fixes a pre-existing compile bug: mcp_policy.rs's policy_with test
helper was missing the ssh_safeguards field added in PR-3.5, silently
breaking the entire policy test module since then. Re-enabling those
tests is the prereq for the hard-deny rework that follows in the next
commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-26 16:04:14 +01:00

1532 lines
58 KiB
Rust

//! Embedded MCP server. Lets a Claude session running anywhere on the
//! same machine — including inside one of tiletopia's own panes — inspect
//! and drive the workspace via Model Context Protocol.
//!
//! Resources (read-only):
//! tiletopia://layout, tiletopia://panes, tiletopia://hosts
//!
//! Read tools:
//! read_pane(leaf_id, last_lines?, after_seq?)
//! wait_for_idle(leaf_id, idle_ms?, timeout_ms?)
//!
//! Write tools (all go through dispatch_action → user policy → confirm
//! modal → audit):
//! set_label, close_pane, swap_panes, promote_pane, apply_preset
//! spawn_pane (local WSL / PowerShell only)
//! connect_host (SSH to a saved host id — the only SSH spawn path)
//! add_host, delete_host (mutate saved-hosts list; gated by an extra
//! 'allow_add_host' safeguard; add_host sanitises extraArgs to reject
//! ProxyCommand / LocalCommand / KnownHostsCommand / PermitLocalCommand
//! =yes — CVE-2023-51385 class local-RCE primitives)
//! write_pane (rate-limited per pane; matched against a non-overridable
//! hard-deny list before user policy)
//!
//! Per-pane `mcpAllow` gate (default-deny) lives in the frontend tree;
//! the frontend mirrors the gated subset into {@link McpState} via the
//! `mcp_update_state` Tauri command. The MCP server only sees what the
//! mirror exposes — no peeking around it.
use std::collections::HashMap;
use std::net::SocketAddr;
use std::path::PathBuf;
use std::sync::Arc;
use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
use anyhow::{Context, Result};
use axum::{
body::Body,
http::{HeaderMap, HeaderValue, Request, StatusCode},
middleware::{self, Next},
response::Response,
Router,
};
use parking_lot::Mutex as PlMutex;
use rmcp::{
handler::server::{router::tool::ToolRouter, wrapper::Parameters},
model::*,
schemars, tool, tool_handler, tool_router,
service::RequestContext,
transport::streamable_http_server::{
session::local::LocalSessionManager,
tower::{StreamableHttpServerConfig, StreamableHttpService},
},
ErrorData as McpError, RoleServer, ServerHandler,
};
use serde::{Deserialize, Serialize};
use serde_json::json;
use tauri::{AppHandle, Emitter, Manager};
use tokio::{net::TcpListener, sync::RwLock, task::JoinHandle};
use tokio_util::sync::CancellationToken;
use crate::pty::{PaneId, PtyManager};
/// Default port for the MCP server. Picked from the IANA-unassigned
/// 47000-range so it's unlikely to collide with anything else on a dev box.
/// Override by editing `port` in `%APPDATA%\com.megaproxy.tiletopia\mcp.json`.
pub const DEFAULT_PORT: u16 = 47821;
const MCP_CONFIG_FILE: &str = "mcp.json";
/// Persisted across restarts so the firewall rule + Claude config snippet
/// don't need re-pasting every launch. Generated on first start.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct McpPersistedConfig {
pub port: u16,
pub token: String,
}
impl McpPersistedConfig {
fn new_default() -> Self {
Self {
port: DEFAULT_PORT,
token: generate_token(),
}
}
}
fn generate_token() -> String {
use rand::RngCore;
let mut buf = [0u8; 32];
rand::rng().fill_bytes(&mut buf);
hex::encode(buf)
}
fn config_path(app: &AppHandle) -> Result<PathBuf> {
let dir = app
.path()
.app_config_dir()
.map_err(|e| anyhow::anyhow!("app_config_dir: {e}"))?;
Ok(dir.join(MCP_CONFIG_FILE))
}
/// Load saved config, or generate-and-save a fresh one on first run.
pub fn load_or_init_config(app: &AppHandle) -> Result<McpPersistedConfig> {
let path = config_path(app)?;
if path.exists() {
let raw = std::fs::read_to_string(&path).context("read mcp.json")?;
let cfg: McpPersistedConfig =
serde_json::from_str(&raw).context("parse mcp.json")?;
return Ok(cfg);
}
let cfg = McpPersistedConfig::new_default();
save_config(app, &cfg)?;
Ok(cfg)
}
pub fn save_config(app: &AppHandle, cfg: &McpPersistedConfig) -> Result<()> {
let path = config_path(app)?;
if let Some(dir) = path.parent() {
std::fs::create_dir_all(dir).context("create_dir_all")?;
}
let tmp = path.with_extension("json.tmp");
let json = serde_json::to_string_pretty(cfg).context("serialize mcp cfg")?;
std::fs::write(&tmp, json.as_bytes()).context("write tmp mcp.json")?;
// Atomic on Unix; MoveFileEx with REPLACE_EXISTING on Windows.
std::fs::rename(&tmp, &path).context("rename mcp.json")?;
Ok(())
}
// ----------------------------------------------------------------------------
// Shared state mirrored from the frontend.
// ----------------------------------------------------------------------------
pub type LeafId = String;
/// Cached snapshot the frontend pushes via `mcp_update_state` whenever the
/// tree or hosts change. Source of truth for everything except scrollback,
/// which the backend collects directly via {@link PtyManager}.
#[derive(Debug, Default, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct McpMirror {
/// Serialised layout tree (full structure, post-filtering happens
/// per-resource — see read_resource).
#[serde(default)]
pub layout_json: String,
/// Map of leaf id → pane metadata. Includes only leaves with
/// `mcpAllow === true` (frontend gates before mirroring).
#[serde(default)]
pub leaves: HashMap<LeafId, MirroredLeaf>,
/// Saved SSH hosts, password fields stripped.
#[serde(default)]
pub hosts: Vec<MirroredHost>,
}
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct MirroredLeaf {
pub pane_id: Option<PaneId>,
pub label: Option<String>,
pub shell_kind: String,
pub distro: Option<String>,
pub ssh_host_id: Option<String>,
#[serde(default)]
pub broadcast: bool,
#[serde(default)]
pub active: bool,
}
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct MirroredHost {
pub id: String,
pub label: String,
pub hostname: String,
pub user: Option<String>,
pub port: Option<u16>,
#[serde(default)]
pub has_password: bool,
}
#[derive(Default)]
pub struct McpState {
pub bearer_token: String,
pub mirror: McpMirror,
}
// ----------------------------------------------------------------------------
// Action reply registry.
// ----------------------------------------------------------------------------
/// Registry of pending frontend action requests. Each entry maps a `requestId`
/// to a oneshot sender that the `mcp_action_reply` Tauri command will fire
/// once the frontend resolves or rejects the action.
///
/// Owned as separate managed state (Arc<PendingActions>) so Tauri commands can
/// grab it via `tauri::State<'_, Arc<PendingActions>>` without needing to lock
/// the entire McpState or pass TileService around.
pub struct PendingActions(
pub PlMutex<HashMap<String, tokio::sync::oneshot::Sender<Result<serde_json::Value, String>>>>,
);
impl Default for PendingActions {
fn default() -> Self {
Self(PlMutex::new(HashMap::new()))
}
}
// ----------------------------------------------------------------------------
// Audit / request event payload types.
// ----------------------------------------------------------------------------
#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
struct McpActionRequest {
request_id: String,
tool: &'static str,
args: serde_json::Value,
needs_confirm: bool,
reason: Option<String>,
}
#[derive(Serialize)]
#[serde(rename_all = "camelCase", tag = "kind")]
enum McpAuditResult {
Ok,
Denied { reason: String, hard: bool },
Failed { msg: String },
}
#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
struct McpAuditEntry {
ts_ms: u64,
tool: &'static str,
args_summary: String,
result: McpAuditResult,
duration_ms: u64,
}
fn now_ms() -> u64 {
SystemTime::now()
.duration_since(UNIX_EPOCH)
.unwrap_or_default()
.as_millis() as u64
}
fn truncate_summary(s: &str) -> String {
if s.len() > 80 {
format!("{}...", &s[..80])
} else {
s.to_string()
}
}
// ----------------------------------------------------------------------------
// Write rate limiter (per OWASP LLM06 "Excessive Agency" + MCP spec MUST).
// Token bucket per leaf_id, only applied to write_pane.
// ----------------------------------------------------------------------------
const WRITE_RATE_CAPACITY: f64 = 30.0;
/// Tokens added per second. 30 / 10s = 3.0 → burst of 30, sustained 3/s.
const WRITE_RATE_REFILL_PER_SEC: f64 = 3.0;
#[derive(Default)]
pub struct WriteRateLimiter {
/// leaf_id → (last_refill, tokens). Naive HashMap that never evicts; for
/// a long-running session with many transient panes this could grow, but
/// LeafIds are uuid-shaped and a few hundred entries is fine.
buckets: PlMutex<HashMap<String, (Instant, f64)>>,
}
impl WriteRateLimiter {
/// Try to consume a token for this leaf. Returns Ok on success, Err with
/// the milliseconds to wait until the next token will be available.
pub fn try_consume(&self, leaf_id: &str) -> Result<(), u64> {
let mut buckets = self.buckets.lock();
let now = Instant::now();
let entry = buckets
.entry(leaf_id.to_string())
.or_insert((now, WRITE_RATE_CAPACITY));
let elapsed = now.saturating_duration_since(entry.0).as_secs_f64();
entry.1 = (entry.1 + elapsed * WRITE_RATE_REFILL_PER_SEC).min(WRITE_RATE_CAPACITY);
entry.0 = now;
if entry.1 >= 1.0 {
entry.1 -= 1.0;
Ok(())
} else {
let wait_secs = (1.0 - entry.1) / WRITE_RATE_REFILL_PER_SEC;
Err((wait_secs * 1000.0).ceil() as u64)
}
}
}
// ----------------------------------------------------------------------------
// MCP service: tools + resources.
// ----------------------------------------------------------------------------
#[derive(Clone)]
pub struct TileService {
ptys: Arc<PtyManager>,
state: Arc<RwLock<McpState>>,
pending: Arc<PendingActions>,
rate_limiter: Arc<WriteRateLimiter>,
app: AppHandle,
tool_router: ToolRouter<Self>,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct ReadPaneArgs {
/// Stable leaf id from the tree (uuid-shaped). Must belong to a pane
/// the user has allow-listed for MCP access.
pub leaf_id: LeafId,
/// Return only the last N lines (default 200, hard cap 3000).
#[serde(default)]
pub last_lines: Option<usize>,
/// Only return bytes whose seq > this. Pair with the `__seq__` value
/// returned in a prior call for incremental polling.
#[serde(default)]
pub after_seq: Option<u64>,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct WaitForIdleArgs {
pub leaf_id: LeafId,
/// Required quiet window before declaring idle (default 500 ms).
#[serde(default)]
pub idle_ms: Option<u64>,
/// Hard timeout in ms; returns timeout=true after this (default 30s,
/// hard cap 5 min).
#[serde(default)]
pub timeout_ms: Option<u64>,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct CloseLeafArgs {
/// Stable leaf id from the tree (uuid-shaped). Must belong to a pane
/// the user has allow-listed for MCP access. Closing the last leaf in
/// the workspace replaces it with a fresh default-shell pane.
pub leaf_id: LeafId,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct SwapPanesArgs {
/// First leaf to swap. Both leaves must be MCP-allowed.
pub leaf_a: LeafId,
/// Second leaf to swap.
pub leaf_b: LeafId,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct PromotePaneArgs {
/// Leaf to promote one level (i.e. swap it with its parent's sibling).
/// No-op if the parent shares orientation with the grandparent —
/// frontend returns a descriptive error in that case.
pub leaf_id: LeafId,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
#[serde(rename_all = "snake_case")]
pub enum PresetName {
/// Replace the workspace with a single full-window pane.
Single,
/// Two columns side-by-side.
TwoColumns,
/// Three columns side-by-side.
ThreeColumns,
/// Two stacked rows.
TwoRows,
/// 2x2 grid.
TwoByTwo,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct ApplyPresetArgs {
pub name: PresetName,
/// Pre-acknowledge that some existing panes may be killed if the
/// preset has fewer slots than the current layout. Required for any
/// non-additive reshape — frontend rejects with the dropped count
/// otherwise.
#[serde(default)]
pub allow_drops: bool,
}
/// MCP-facing spawn spec — same shape as pty::SpawnSpec but without the
/// Ssh variant. Claude's spawn_pane only opens local shells; SSH goes
/// through the dedicated connect_host tool which takes a host_id and
/// handles the lookup. Two clearly-scoped tools beats one tool with a
/// half-broken SSH path.
#[derive(Debug, Clone, Deserialize, Serialize, schemars::JsonSchema)]
#[serde(tag = "kind", rename_all = "lowercase")]
pub enum McpSpawnSpec {
Wsl {
distro: Option<String>,
cwd: Option<String>,
},
Powershell,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct SpawnPaneArgs {
/// What local shell to run in the new pane: WSL distro or PowerShell.
/// For SSH connections to saved hosts, use the connect_host tool
/// instead — it takes a host_id and looks the rest up for you.
pub spec: McpSpawnSpec,
/// Where to insert the new pane. Defaults to the active pane, or the
/// workspace root if no pane is active. The parent leaf must be
/// MCP-allowed for Claude to target it.
#[serde(default)]
pub parent_leaf_id: Option<LeafId>,
/// "h" → new pane to the right; "v" → new pane below. If omitted,
/// picks based on the parent's current aspect ratio (wider → "h",
/// taller → "v"), matching the titlebar "+" button's behaviour.
#[serde(default)]
pub orientation: Option<String>,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct ConnectHostArgs {
/// Stable id of a host saved via the SSH host manager. The new pane
/// inherits the host's user/port/identity-file/etc. and reuses the
/// keyring-stored password (if any) for auto-fill at the SSH prompt.
pub host_id: String,
/// Same semantics as spawn_pane.parent_leaf_id.
#[serde(default)]
pub parent_leaf_id: Option<LeafId>,
/// Same semantics as spawn_pane.orientation.
#[serde(default)]
pub orientation: Option<String>,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct AddHostArgs {
/// Human-readable name for the host (shown in the picker / palette).
/// If omitted, defaults to `hostname` server-side.
#[serde(default)]
pub label: Option<String>,
/// Hostname or IP. Required. Rejected if it starts with '-' or contains
/// control characters (CVE-2023-51385 / smuggled-flag class).
pub hostname: String,
/// SSH login user. Same validation as hostname.
#[serde(default)]
pub user: Option<String>,
/// TCP port. Defaults to 22 if omitted.
#[serde(default)]
pub port: Option<u16>,
/// Path to a private key. Passed to ssh as `-i`.
#[serde(default, rename = "identityFile")]
pub identity_file: Option<String>,
/// `user@host[:port]` jump host. Same validation as hostname.
#[serde(default, rename = "jumpHost")]
pub jump_host: Option<String>,
/// Extra ssh args (e.g. `-o ServerAliveInterval=30`). Sanitised to
/// reject command-execution `-o` options: ProxyCommand, LocalCommand,
/// KnownHostsCommand, PermitLocalCommand=yes. The user's manually-added
/// hosts are unrestricted; only this MCP path is gated.
#[serde(default, rename = "extraArgs")]
pub extra_args: Option<Vec<String>>,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct DeleteHostArgs {
/// Stable id of a host returned by tiletopia://hosts or a prior
/// add_host call. Deleting also sweeps any saved password for the
/// host from the OS keyring.
pub host_id: String,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct WritePaneArgs {
/// Stable leaf id from the tree (uuid-shaped). Must belong to a pane
/// the user has allow-listed for MCP access.
pub leaf_id: LeafId,
/// Bytes to send to the pane's PTY. Use "\n" for Enter. Each call sends
/// one chunk; partial commands are fine but block the shell until you
/// send a newline. This is the highest-risk MCP tool — Claude can send
/// arbitrary keystrokes including destructive commands. The policy
/// engine + hard-deny list are evaluated against this text directly.
/// Rate-limited to 30 calls / 10s per pane.
pub text: String,
}
#[derive(Debug, Deserialize, schemars::JsonSchema)]
pub struct SetLabelArgs {
/// Stable leaf id from the tree (uuid-shaped). Must belong to a pane
/// the user has allow-listed for MCP access.
pub leaf_id: LeafId,
/// New human-readable label. Pass an empty string to clear the label.
pub label: String,
}
const READ_PANE_HARD_CAP_LINES: usize = 3000;
const WAIT_TIMEOUT_HARD_CAP_MS: u64 = 5 * 60 * 1000;
#[tool_router]
impl TileService {
pub fn new(
ptys: Arc<PtyManager>,
state: Arc<RwLock<McpState>>,
pending: Arc<PendingActions>,
rate_limiter: Arc<WriteRateLimiter>,
app: AppHandle,
) -> Self {
Self {
ptys,
state,
pending,
rate_limiter,
app,
tool_router: Self::tool_router(),
}
}
/// Dispatch an action that the frontend must execute. Generates a uuid,
/// registers a oneshot, emits the "mcp://request" event with the args,
/// awaits the reply with a 30s timeout. Also emits an "mcp://audit" event
/// after the call resolves (regardless of outcome).
async fn dispatch_action(
&self,
tool: &'static str,
args: serde_json::Value,
args_repr: String,
) -> Result<serde_json::Value, McpError> {
let start_ms = now_ms();
let args_summary = truncate_summary(&args_repr);
tracing::debug!(tool, args_repr = %args_repr, "dispatch_action: start");
// 1. Load user policy.
let policy = crate::mcp_policy::load_or_init(&self.app)
.map_err(|e| McpError::internal_error(e.to_string(), None))?;
// 2. Hard-deny check (for any tool — is_hard_denied checks for shell
// catastrophe patterns; for non-write_pane tools the patterns are
// unlikely to match args_repr but the check is cheap and safe).
if let Some(label) = crate::mcp_policy::is_hard_denied(&args_repr) {
let duration_ms = now_ms() - start_ms;
let audit = McpAuditEntry {
ts_ms: start_ms,
tool,
args_summary: args_summary.clone(),
result: McpAuditResult::Denied {
reason: label.to_string(),
hard: true,
},
duration_ms,
};
tracing::debug!(tool, reason = label, hard = true, "dispatch_action: hard-denied");
let _ = self.app.emit("mcp://audit", &audit);
return Err(McpError::invalid_params(
format!("hard-denied: {label}"),
None,
));
}
// 3. Evaluate user-policy decision.
let decision = crate::mcp_policy::evaluate(&policy, tool, &args_repr);
tracing::debug!(tool, ?decision, "dispatch_action: policy decision");
// 4. Handle Deny.
let (needs_confirm, ask_reason) = match &decision {
crate::mcp_policy::PolicyDecision::Allow => (false, None),
crate::mcp_policy::PolicyDecision::Ask { reason } => {
(true, Some(reason.clone()))
}
crate::mcp_policy::PolicyDecision::Deny { reason, hard } => {
let duration_ms = now_ms() - start_ms;
let audit = McpAuditEntry {
ts_ms: start_ms,
tool,
args_summary: args_summary.clone(),
result: McpAuditResult::Denied {
reason: reason.clone(),
hard: *hard,
},
duration_ms,
};
tracing::debug!(tool, reason = %reason, hard, "dispatch_action: denied by policy");
let _ = self.app.emit("mcp://audit", &audit);
return Err(McpError::invalid_params(
format!("denied: {reason}"),
None,
));
}
};
// 5. Generate a unique request id, register oneshot, emit mcp://request.
// uuid crate is not in Cargo.toml; generate via rand (already a dep).
// TODO: if uuid (v4 feature) is added to Cargo.toml, replace with:
// let request_id = uuid::Uuid::new_v4().to_string();
let request_id = {
use rand::RngCore;
let mut bytes = [0u8; 16];
rand::rng().fill_bytes(&mut bytes);
// Format as a RFC-4122-style UUID v4 string for frontend interop.
bytes[6] = (bytes[6] & 0x0f) | 0x40;
bytes[8] = (bytes[8] & 0x3f) | 0x80;
format!(
"{:02x}{:02x}{:02x}{:02x}-{:02x}{:02x}-{:02x}{:02x}-{:02x}{:02x}-{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}",
bytes[0], bytes[1], bytes[2], bytes[3],
bytes[4], bytes[5],
bytes[6], bytes[7],
bytes[8], bytes[9],
bytes[10], bytes[11], bytes[12], bytes[13], bytes[14], bytes[15],
)
};
let (tx, rx) = tokio::sync::oneshot::channel();
{
self.pending.0.lock().insert(request_id.clone(), tx);
}
let payload = McpActionRequest {
request_id: request_id.clone(),
tool,
args,
needs_confirm,
reason: ask_reason,
};
tracing::debug!(tool, request_id = %request_id, needs_confirm, "dispatch_action: emitting mcp://request");
let _ = self.app.emit("mcp://request", &payload);
// 6. Await reply with 30s timeout.
// 60s is the outer cap. Per-tool inner timeouts (waitForPaneRegistration
// in the frontend handler) are tighter for fast ops and looser for
// SSH/spawn — this just keeps a misbehaving frontend from leaking a
// request id forever.
let result = tokio::time::timeout(Duration::from_secs(60), rx).await;
let duration_ms = now_ms() - start_ms;
match result {
Err(_elapsed) => {
// Timeout — remove stale sender from registry.
self.pending.0.lock().remove(&request_id);
let audit = McpAuditEntry {
ts_ms: start_ms,
tool,
args_summary,
result: McpAuditResult::Failed {
msg: "timeout".into(),
},
duration_ms,
};
tracing::debug!(tool, request_id = %request_id, "dispatch_action: timed out");
let _ = self.app.emit("mcp://audit", &audit);
Err(McpError::internal_error(
"action timed out waiting for frontend response",
Some(json!({ "requestId": request_id })),
))
}
Ok(Err(_recv_err)) => {
// Sender was dropped (shouldn't happen normally).
let audit = McpAuditEntry {
ts_ms: start_ms,
tool,
args_summary,
result: McpAuditResult::Failed {
msg: "channel closed".into(),
},
duration_ms,
};
tracing::debug!(tool, request_id = %request_id, "dispatch_action: channel closed");
let _ = self.app.emit("mcp://audit", &audit);
Err(McpError::internal_error(
"action channel closed unexpectedly",
Some(json!({ "requestId": request_id })),
))
}
Ok(Ok(reply)) => {
// 7. On reply: emit audit, propagate. Destructure with
// ownership so the success payload and the error string
// move out cleanly (avoids borrow-then-move on `reply`).
let (audit_result, err, ok_payload) = match reply {
Ok(v) => {
tracing::debug!(tool, request_id = %request_id, "dispatch_action: reply ok");
(McpAuditResult::Ok, None, Some(v))
}
Err(msg) => {
tracing::debug!(tool, request_id = %request_id, error = %msg, "dispatch_action: reply error");
(
McpAuditResult::Failed { msg: msg.clone() },
Some(McpError::internal_error(msg, None)),
None,
)
}
};
let audit = McpAuditEntry {
ts_ms: start_ms,
tool,
args_summary,
result: audit_result,
duration_ms,
};
let _ = self.app.emit("mcp://audit", &audit);
match err {
Some(e) => Err(e),
None => Ok(ok_payload.expect("ok branch always sets ok_payload")),
}
}
}
}
/// Look up a leaf_id → pane_id under the MCP-allow gate.
async fn resolve_pane(&self, leaf_id: &str) -> Result<PaneId, McpError> {
let st = self.state.read().await;
let leaf = st.mirror.leaves.get(leaf_id).ok_or_else(|| {
McpError::invalid_params(
"unknown leaf_id (not visible to MCP; user may need to allow it)",
Some(json!({ "leaf_id": leaf_id })),
)
})?;
leaf.pane_id.ok_or_else(|| {
McpError::invalid_params(
"leaf has no live pane",
Some(json!({ "leaf_id": leaf_id })),
)
})
}
#[tool(description = "Read the recent scrollback of a terminal pane. \
Returns text plus a __seq__=N marker that can be passed back as \
after_seq for incremental polling.")]
async fn read_pane(
&self,
Parameters(args): Parameters<ReadPaneArgs>,
) -> Result<CallToolResult, McpError> {
let pane_id = self.resolve_pane(&args.leaf_id).await?;
let ring = self.ptys.ring(pane_id).ok_or_else(|| {
McpError::internal_error(
"pane ring missing (pane may have just exited)",
Some(json!({ "leaf_id": args.leaf_id })),
)
})?;
let (bytes, seq) = {
let g = ring.lock();
g.snapshot()
};
// Trim by after_seq if provided: bytes in the ring beyond
// `after_seq` is `seq - after_seq`, clamped against ring size.
let start = match args.after_seq {
Some(prev) if seq > prev => {
let new_bytes = (seq - prev) as usize;
bytes.len().saturating_sub(new_bytes)
}
Some(_) => bytes.len(),
None => 0,
};
let tail = &bytes[start..];
let text = String::from_utf8_lossy(tail);
let cap = args
.last_lines
.map(|n| n.min(READ_PANE_HARD_CAP_LINES))
.unwrap_or(200);
let limited: String = if cap == 0 {
String::new()
} else {
let lines: Vec<&str> = text.lines().collect();
let start_line = lines.len().saturating_sub(cap);
lines[start_line..].join("\n")
};
Ok(CallToolResult::success(vec![
Content::text(limited),
Content::text(format!("__seq__={seq}")),
]))
}
#[tool(description = "Block until a pane has been quiet (no output) \
for idle_ms, or timeout_ms elapses. Useful for command-completion \
synchronisation. Returns {idle:bool, seq:u64, elapsed_ms:u64}.")]
async fn wait_for_idle(
&self,
Parameters(args): Parameters<WaitForIdleArgs>,
) -> Result<CallToolResult, McpError> {
let pane_id = self.resolve_pane(&args.leaf_id).await?;
let ring = self.ptys.ring(pane_id).ok_or_else(|| {
McpError::internal_error("pane ring missing", None)
})?;
let idle_target = Duration::from_millis(args.idle_ms.unwrap_or(500));
let timeout = Duration::from_millis(
args.timeout_ms
.unwrap_or(30_000)
.min(WAIT_TIMEOUT_HARD_CAP_MS),
);
let start = Instant::now();
let mut last_seq = ring.lock().snapshot().1;
let mut last_change = Instant::now();
loop {
// Sleep in small slices so we notice both incoming data and
// the overall timeout promptly.
tokio::time::sleep(Duration::from_millis(50)).await;
let now_seq = ring.lock().snapshot().1;
if now_seq != last_seq {
last_seq = now_seq;
last_change = Instant::now();
}
if last_change.elapsed() >= idle_target {
return Ok(CallToolResult::success(vec![Content::text(
json!({
"idle": true,
"seq": last_seq,
"elapsed_ms": start.elapsed().as_millis() as u64,
})
.to_string(),
)]));
}
if start.elapsed() >= timeout {
return Ok(CallToolResult::success(vec![Content::text(
json!({
"idle": false,
"seq": last_seq,
"elapsed_ms": start.elapsed().as_millis() as u64,
})
.to_string(),
)]));
}
}
}
#[tool(description = "Send keystrokes (text) to a pane's PTY. The leaf \
must be MCP-allowed. Use \"\\n\" for Enter. Rate-limited per pane: \
30 calls per 10 seconds. The user policy is evaluated against the \
sent text (so rules like write_pane(git push *) match by content), \
and a compiled-in hard-deny list always catches rm -rf /, fork \
bombs, mkfs on devices, etc. — those are blocked regardless of \
policy.")]
async fn write_pane(
&self,
Parameters(args): Parameters<WritePaneArgs>,
) -> Result<CallToolResult, McpError> {
let _leaf = self.require_visible_leaf(&args.leaf_id).await?;
// Rate limit BEFORE dispatch — we don't want a misbehaving client
// to spam the user with confirm modals or burn audit-log capacity.
if let Err(retry_after_ms) = self.rate_limiter.try_consume(&args.leaf_id) {
tracing::warn!(
leaf_id = %args.leaf_id,
retry_after_ms,
"write_pane: rate limited"
);
return Err(McpError::invalid_params(
format!("rate limited; retry after {retry_after_ms}ms"),
Some(json!({
"leaf_id": &args.leaf_id,
"retry_after_ms": retry_after_ms,
})),
));
}
// args_repr IS the text — that's what hard-deny and the user's
// policy globs pattern-match against. (For other tools we use a
// stable summary string; for write_pane the text is the surface.)
let args_repr = args.text.clone();
let args_json = json!({ "leafId": &args.leaf_id, "text": &args.text });
tracing::debug!(
leaf_id = %args.leaf_id,
bytes = args.text.len(),
"write_pane: dispatching"
);
let _ = self
.dispatch_action("write_pane", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text("ok")]))
}
#[tool(description = "Spawn a new local-shell pane next to an existing \
one — WSL distro or PowerShell. The new pane is auto-allowed for \
MCP so Claude can immediately read its scrollback and send it \
keystrokes (subject to policy). Returns {leafId, paneId} for the \
newly created pane. Times out after ~15 seconds if the PTY can't \
be spawned (covers a cold WSL distro start). \
FOR SSH: use connect_host(host_id) instead — it looks the host up \
from the saved-hosts list for you.")]
async fn spawn_pane(
&self,
Parameters(args): Parameters<SpawnPaneArgs>,
) -> Result<CallToolResult, McpError> {
// If a parent is named, it must be MCP-allowed. (If omitted, the
// frontend picks the active pane or root — no explicit check here
// since the user already approved an MCP-server-running state.)
if let Some(ref parent) = args.parent_leaf_id {
let _ = self.require_visible_leaf(parent).await?;
}
// Serialise the spec back to JSON so the frontend handler can
// reconstruct it without us doing the per-kind dispatch here.
let spec_json = serde_json::to_value(&args.spec).map_err(|e| {
McpError::internal_error(
format!("serialize spec: {e}"),
None,
)
})?;
let kind_str = match &args.spec {
McpSpawnSpec::Wsl { .. } => "wsl",
McpSpawnSpec::Powershell => "powershell",
};
let args_repr = format!(
"shell={} parent={} orientation={}",
kind_str,
args.parent_leaf_id.as_deref().unwrap_or("(active)"),
args.orientation.as_deref().unwrap_or("(auto)"),
);
let args_json = json!({
"spec": spec_json,
"parentLeafId": args.parent_leaf_id,
"orientation": args.orientation,
});
tracing::debug!(shell = kind_str, "spawn_pane: dispatching");
let result = self
.dispatch_action("spawn_pane", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text(
result.to_string(),
)]))
}
#[tool(description = "Open a new pane connected to a saved SSH host. \
Thin wrapper around spawn_pane that resolves host_id against the \
saved-hosts list (use the tiletopia://hosts resource to list them). \
Returns {leafId, paneId} for the new pane. The user's saved password \
for the host (if any) is auto-typed at the prompt — passwords are \
never exposed through the MCP surface.")]
async fn connect_host(
&self,
Parameters(args): Parameters<ConnectHostArgs>,
) -> Result<CallToolResult, McpError> {
if !self.policy_ssh_open_allowed().await {
return Err(McpError::invalid_params(
"ssh-disabled: Claude is not allowed to open SSH connections \
(Policy tab → SSH safeguards → 'Allow Claude to open SSH \
connections'). Open the SSH session manually via the \
titlebar 🔑 picker first, then ask Claude to interact with \
it.",
None,
));
}
if let Some(ref parent) = args.parent_leaf_id {
let _ = self.require_visible_leaf(parent).await?;
}
// Verify host_id is in the mirror (so Claude can't probe unknown ids).
let host_known = {
let st = self.state.read().await;
st.mirror.hosts.iter().any(|h| h.id == args.host_id)
};
if !host_known {
return Err(McpError::invalid_params(
"unknown host_id (use tiletopia://hosts to list saved hosts)",
Some(json!({ "host_id": &args.host_id })),
));
}
let args_repr = format!(
"host={} parent={} orientation={}",
&args.host_id,
args.parent_leaf_id.as_deref().unwrap_or("(active)"),
args.orientation.as_deref().unwrap_or("(auto)"),
);
let args_json = json!({
"hostId": &args.host_id,
"parentLeafId": args.parent_leaf_id,
"orientation": args.orientation,
});
tracing::debug!(host_id = %args.host_id, "connect_host: dispatching");
let result = self
.dispatch_action("connect_host", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text(
result.to_string(),
)]))
}
#[tool(description = "Register a new SSH host in the saved-hosts list \
(the same store the titlebar 🔑 picker manages). Validates hostname/\
user/jumpHost the same way an SSH spawn would (rejects '-' prefixes \
and control characters, CVE-2023-51385 class) and sanitises extraArgs \
to reject ProxyCommand / LocalCommand / KnownHostsCommand / \
PermitLocalCommand=yes (local-RCE primitives). Gated by the \
'Allow Claude to save or delete SSH hosts' switch in the Policy tab; \
refuses with 'add-host-disabled' when off. Returns {hostId} for the \
newly-saved host — pass to connect_host to open it.")]
async fn add_host(
&self,
Parameters(args): Parameters<AddHostArgs>,
) -> Result<CallToolResult, McpError> {
if !self.policy_ssh_add_host_allowed().await {
return Err(McpError::invalid_params(
"add-host-disabled: Claude is not allowed to save SSH hosts \
(Policy tab → SSH safeguards → 'Allow Claude to save or \
delete SSH hosts'). Ask the user to add the host manually \
via the titlebar 🔑 picker.",
None,
));
}
// Same token validation ssh.exe would do at spawn time — reject up
// front so we don't persist a host that can never be opened.
crate::pty::validate_ssh_token("hostname", &args.hostname)
.map_err(|e| McpError::invalid_params(e.to_string(), None))?;
if let Some(u) = args.user.as_deref() {
crate::pty::validate_ssh_token("user", u)
.map_err(|e| McpError::invalid_params(e.to_string(), None))?;
}
if let Some(jh) = args.jump_host.as_deref() {
crate::pty::validate_ssh_token("jump host", jh)
.map_err(|e| McpError::invalid_params(e.to_string(), None))?;
}
if let Some(extra) = args.extra_args.as_deref() {
crate::hosts::sanitize_extra_args(extra)
.map_err(|reason| McpError::invalid_params(reason, None))?;
}
let label = args
.label
.as_deref()
.map(|s| s.trim())
.filter(|s| !s.is_empty())
.unwrap_or_else(|| args.hostname.trim())
.to_string();
let args_repr = format!(
"label={} hostname={} user={} port={}",
label,
&args.hostname,
args.user.as_deref().unwrap_or("(default)"),
args.port
.map(|p| p.to_string())
.unwrap_or_else(|| "(default)".into()),
);
let args_json = json!({
"label": label,
"hostname": &args.hostname,
"user": args.user,
"port": args.port,
"identityFile": args.identity_file,
"jumpHost": args.jump_host,
"extraArgs": args.extra_args,
});
tracing::debug!(hostname = %args.hostname, "add_host: dispatching");
let result = self
.dispatch_action("add_host", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text(
result.to_string(),
)]))
}
#[tool(description = "Delete a saved SSH host by id. Sweeps any saved \
password for the host from the OS keyring as a side effect. Gated by \
the same 'Allow Claude to save or delete SSH hosts' switch as \
add_host; refuses with 'add-host-disabled' when off.")]
async fn delete_host(
&self,
Parameters(args): Parameters<DeleteHostArgs>,
) -> Result<CallToolResult, McpError> {
if !self.policy_ssh_add_host_allowed().await {
return Err(McpError::invalid_params(
"add-host-disabled: Claude is not allowed to delete SSH hosts \
(Policy tab → SSH safeguards → 'Allow Claude to save or \
delete SSH hosts').",
None,
));
}
// Verify the host_id is in the mirror so Claude can't probe arbitrary
// ids. The mirror is the authoritative view of what Claude can see.
let host_label = {
let st = self.state.read().await;
st.mirror
.hosts
.iter()
.find(|h| h.id == args.host_id)
.map(|h| h.label.clone())
};
let label = host_label.ok_or_else(|| {
McpError::invalid_params(
"unknown host_id (use tiletopia://hosts to list saved hosts)",
Some(json!({ "host_id": &args.host_id })),
)
})?;
let args_repr = format!("hostId={} label={}", &args.host_id, &label);
let args_json = json!({ "hostId": &args.host_id });
tracing::debug!(host_id = %args.host_id, "delete_host: dispatching");
let _ = self
.dispatch_action("delete_host", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text("ok")]))
}
#[tool(description = "Set or clear the human-readable label on a pane. \
Pass empty string to clear. The leaf must be MCP-allowed.")]
async fn set_label(
&self,
Parameters(args): Parameters<SetLabelArgs>,
) -> Result<CallToolResult, McpError> {
// Validate leaf exists in mirror + is visible to MCP (mcpAllow=true
// is enforced by the frontend before mirroring, so presence here
// implies the user has allowed it).
let _leaf = self
.state
.read()
.await
.mirror
.leaves
.get(&args.leaf_id)
.cloned()
.ok_or_else(|| {
McpError::invalid_params(
"unknown leaf_id (not visible to MCP; user may need to allow it)",
Some(json!({ "leaf_id": &args.leaf_id })),
)
})?;
let args_repr = format!("leafId={} label={}", &args.leaf_id, &args.label);
let args_json = json!({ "leafId": &args.leaf_id, "label": &args.label });
tracing::debug!(leaf_id = %args.leaf_id, label = %args.label, "set_label: dispatching");
let _ = self
.dispatch_action("set_label", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text("ok")]))
}
#[tool(description = "Close a pane and kill its PTY. The leaf must be \
MCP-allowed. Closing the only leaf in the workspace replaces it \
with a fresh default-shell pane (the workspace can never be empty).")]
async fn close_pane(
&self,
Parameters(args): Parameters<CloseLeafArgs>,
) -> Result<CallToolResult, McpError> {
let _leaf = self.require_visible_leaf(&args.leaf_id).await?;
let args_repr = format!("leafId={}", &args.leaf_id);
let args_json = json!({ "leafId": &args.leaf_id });
tracing::debug!(leaf_id = %args.leaf_id, "close_pane: dispatching");
let _ = self
.dispatch_action("close_pane", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text("ok")]))
}
#[tool(description = "Swap two panes in the layout tree (preserves \
both PTYs and their labels). Both leaves must be MCP-allowed.")]
async fn swap_panes(
&self,
Parameters(args): Parameters<SwapPanesArgs>,
) -> Result<CallToolResult, McpError> {
let _a = self.require_visible_leaf(&args.leaf_a).await?;
let _b = self.require_visible_leaf(&args.leaf_b).await?;
let args_repr = format!("leafA={} leafB={}", &args.leaf_a, &args.leaf_b);
let args_json = json!({ "leafA": &args.leaf_a, "leafB": &args.leaf_b });
tracing::debug!(leaf_a = %args.leaf_a, leaf_b = %args.leaf_b, "swap_panes: dispatching");
let _ = self
.dispatch_action("swap_panes", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text("ok")]))
}
#[tool(description = "Promote a pane up one level — swaps it with its \
parent split's sibling subtree. Useful for un-nesting a pane that \
ended up deeper than intended. No-op (errors) if the pane's parent \
shares orientation with its grandparent — no perpendicular promote \
target exists.")]
async fn promote_pane(
&self,
Parameters(args): Parameters<PromotePaneArgs>,
) -> Result<CallToolResult, McpError> {
let _leaf = self.require_visible_leaf(&args.leaf_id).await?;
let args_repr = format!("leafId={}", &args.leaf_id);
let args_json = json!({ "leafId": &args.leaf_id });
tracing::debug!(leaf_id = %args.leaf_id, "promote_pane: dispatching");
let _ = self
.dispatch_action("promote_pane", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text("ok")]))
}
#[tool(description = "Reshape the workspace to a preset layout. \
Existing panes are slotted into the new shape in order (ids + PTYs \
preserved where possible); extra slots spawn fresh shells. If the \
preset has fewer slots than the current pane count, set \
allow_drops=true to acknowledge that those overflow panes will be \
killed — otherwise the call fails with the dropped count so you \
can decide.")]
async fn apply_preset(
&self,
Parameters(args): Parameters<ApplyPresetArgs>,
) -> Result<CallToolResult, McpError> {
// Convert the typed enum back to a stable wire-form string the
// frontend dispatcher matches against. Matching the snake_case of
// PresetName's serde rename_all so JSON round-trip stays clean.
let name = match args.name {
PresetName::Single => "single",
PresetName::TwoColumns => "two_columns",
PresetName::ThreeColumns => "three_columns",
PresetName::TwoRows => "two_rows",
PresetName::TwoByTwo => "two_by_two",
};
let args_repr = format!("preset={} allowDrops={}", name, args.allow_drops);
let args_json = json!({ "name": name, "allowDrops": args.allow_drops });
tracing::debug!(preset = name, allow_drops = args.allow_drops, "apply_preset: dispatching");
let _ = self
.dispatch_action("apply_preset", args_json, args_repr)
.await?;
Ok(CallToolResult::success(vec![Content::text("ok")]))
}
/// Read the persisted SSH-safeguard switch. Fresh-read every call so a
/// user editing the policy in the panel takes effect on the next MCP
/// call without a server restart. Errors fall back to the safe default
/// (refuse).
async fn policy_ssh_open_allowed(&self) -> bool {
match crate::mcp_policy::load_or_init(&self.app) {
Ok(p) => p.ssh_safeguards.allow_open_ssh,
Err(e) => {
tracing::warn!(error = %e, "policy_ssh_open_allowed: load failed, defaulting to false");
false
}
}
}
/// Mirror of policy_ssh_open_allowed for the add_host/delete_host pair.
async fn policy_ssh_add_host_allowed(&self) -> bool {
match crate::mcp_policy::load_or_init(&self.app) {
Ok(p) => p.ssh_safeguards.allow_add_host,
Err(e) => {
tracing::warn!(error = %e, "policy_ssh_add_host_allowed: load failed, defaulting to false");
false
}
}
}
/// Shared validation for tools that target an existing leaf — confirms
/// the leaf is in the mirror (which means the user has it allow-listed
/// for MCP) and returns its metadata. Factored out of the 4+ tools that
/// need this exact check.
async fn require_visible_leaf(&self, leaf_id: &str) -> Result<MirroredLeaf, McpError> {
self.state
.read()
.await
.mirror
.leaves
.get(leaf_id)
.cloned()
.ok_or_else(|| {
McpError::invalid_params(
"unknown leaf_id (not visible to MCP; user may need to allow it)",
Some(json!({ "leaf_id": leaf_id })),
)
})
}
}
#[tool_handler]
impl ServerHandler for TileService {
fn get_info(&self) -> ServerInfo {
ServerInfo::new(
ServerCapabilities::builder()
.enable_tools()
.enable_resources()
.build(),
)
.with_server_info(Implementation::from_build_env())
.with_protocol_version(ProtocolVersion::V_2024_11_05)
.with_instructions(
"Tiletopia MCP — drive a multi-pane terminal workspace.\n\
\n\
Resources (read): tiletopia://layout, tiletopia://panes, \
tiletopia://hosts.\n\
\n\
Read tools: read_pane (scrollback), wait_for_idle (block \
until a pane goes quiet).\n\
\n\
Write tools (subject to user policy + confirm modal):\n\
- set_label, close_pane, swap_panes, promote_pane, \
apply_preset — tree shape and metadata.\n\
- spawn_pane (local WSL/PowerShell), connect_host (SSH to a \
saved host — use this for SSH, not spawn_pane).\n\
- add_host, delete_host (mutate the saved-hosts list; \
add_host's extraArgs are sanitised — ProxyCommand and \
friends are refused).\n\
- write_pane (send keystrokes; rate-limited; matched against \
user policy + a non-overridable hard-deny list for the \
worst-of-the-worst patterns).\n\
\n\
Only panes the user has allow-listed (🤖 chip on) are \
visible. SSH spawns are gated by an extra Policy-tab switch \
that's off by default — if you see 'ssh-disabled' errors, \
the user has not enabled MCP-initiated SSH. add_host / \
delete_host are similarly gated by an 'allow_add_host' \
switch — 'add-host-disabled' means the user manages SSH \
hosts manually via the titlebar 🔑 picker.",
)
}
async fn list_resources(
&self,
_r: Option<PaginatedRequestParams>,
_: RequestContext<RoleServer>,
) -> Result<ListResourcesResult, McpError> {
Ok(ListResourcesResult {
resources: vec![
RawResource::new("tiletopia://layout", "layout").no_annotation(),
RawResource::new("tiletopia://panes", "panes").no_annotation(),
RawResource::new("tiletopia://hosts", "hosts").no_annotation(),
],
next_cursor: None,
meta: None,
})
}
async fn read_resource(
&self,
req: ReadResourceRequestParams,
_: RequestContext<RoleServer>,
) -> Result<ReadResourceResult, McpError> {
let state = self.state.read().await;
let body = match req.uri.as_str() {
"tiletopia://layout" => state.mirror.layout_json.clone(),
"tiletopia://panes" => {
serde_json::to_string(&state.mirror.leaves).unwrap_or_default()
}
"tiletopia://hosts" => {
serde_json::to_string(&state.mirror.hosts).unwrap_or_default()
}
other => {
return Err(McpError::resource_not_found(
"resource_not_found",
Some(json!({ "uri": other })),
));
}
};
Ok(ReadResourceResult::new(vec![ResourceContents::text(
body, req.uri,
)]))
}
async fn list_resource_templates(
&self,
_r: Option<PaginatedRequestParams>,
_: RequestContext<RoleServer>,
) -> Result<ListResourceTemplatesResult, McpError> {
Ok(ListResourceTemplatesResult {
resource_templates: vec![],
next_cursor: None,
meta: None,
})
}
}
// ----------------------------------------------------------------------------
// HTTP wiring + bearer auth.
// ----------------------------------------------------------------------------
async fn bearer_auth(
axum::extract::State(expected): axum::extract::State<Arc<String>>,
headers: HeaderMap,
req: Request<Body>,
next: Next,
) -> Result<Response, Response> {
// OAuth-discovery clients probe /.well-known/* and /register before any
// /mcp request. Letting those fall through to axum's default 404 keeps
// us out of the OAuth challenge/response game — bearer enforcement only
// applies to the real MCP surface.
if !req.uri().path().starts_with("/mcp") {
return Ok(next.run(req).await);
}
let auth_header = headers
.get(axum::http::header::AUTHORIZATION)
.and_then(|v| v.to_str().ok());
let supplied = auth_header.and_then(|s| s.strip_prefix("Bearer "));
let ok = supplied
.map(|t| constant_time_eq(t.as_bytes(), expected.as_bytes()))
.unwrap_or(false);
tracing::debug!(
method = %req.method(),
path = %req.uri().path(),
auth_present = auth_header.is_some(),
bearer_present = supplied.is_some(),
token_match = ok,
"MCP request"
);
if ok {
return Ok(next.run(req).await);
}
let mut resp = Response::builder()
.status(StatusCode::UNAUTHORIZED)
.body(Body::empty())
.unwrap();
resp.headers_mut().insert(
axum::http::header::WWW_AUTHENTICATE,
HeaderValue::from_static(r#"Bearer realm="tiletopia""#),
);
Err(resp)
}
fn constant_time_eq(a: &[u8], b: &[u8]) -> bool {
if a.len() != b.len() {
return false;
}
let mut d = 0u8;
for (x, y) in a.iter().zip(b) {
d |= x ^ y;
}
d == 0
}
// ----------------------------------------------------------------------------
// Lifecycle.
// ----------------------------------------------------------------------------
pub struct RunningServer {
pub addr: SocketAddr,
pub token: String,
pub cancel: CancellationToken,
pub task: JoinHandle<()>,
}
#[derive(Default)]
pub struct McpServerHandle(pub PlMutex<Option<RunningServer>>);
pub async fn start_server(
app_handle: AppHandle,
ptys: Arc<PtyManager>,
state: Arc<RwLock<McpState>>,
pending: Arc<PendingActions>,
) -> Result<RunningServer> {
let cfg = load_or_init_config(&app_handle)?;
let token = cfg.token.clone();
state.write().await.bearer_token = token.clone();
let cancel = CancellationToken::new();
// Fresh service per session; cheap because we share state via Arcs.
let ptys_f = ptys.clone();
let state_f = state.clone();
let pending_f = pending.clone();
// Single shared rate limiter for the lifetime of this server — token
// buckets are per-leaf-id, but the registry itself is one piece of state.
let rate_limiter: Arc<WriteRateLimiter> = Arc::new(WriteRateLimiter::default());
// Clone AppHandle before the move closure so we can pass it into each
// TileService instance. AppHandle is cheap to clone (it's an Arc inside).
let app_handle_for_service = app_handle.clone();
// Disable rmcp's DNS-rebinding host allowlist. The default only permits
// localhost / 127.0.0.1 / ::1; legitimate WSL clients connect via the
// dynamic WSL gateway IP (172.x.x.1) which can't be in any static list.
// Bearer-token auth on /mcp is the real gatekeeper, and we're not
// running in a browser context where DNS rebinding is a concern.
let mcp_service = StreamableHttpService::new(
move || {
Ok(TileService::new(
ptys_f.clone(),
state_f.clone(),
pending_f.clone(),
rate_limiter.clone(),
app_handle_for_service.clone(),
))
},
LocalSessionManager::default().into(),
StreamableHttpServerConfig::default().disable_allowed_hosts(),
);
let router = Router::new()
.nest_service("/mcp", mcp_service)
.layer(middleware::from_fn_with_state(
Arc::new(token.clone()),
bearer_auth,
));
// Bind to all interfaces so WSL distros in NAT mode can reach the server
// via the Windows host's WSL-side adapter IP. Auth is bearer-token only.
// We report 127.0.0.1 in the URL since that's the canonical Windows-side
// hostname (WSL clients swap in the gateway IP).
//
// Try the saved port first so the user's firewall rule + Claude config
// survive restarts. If it's taken, fall back to an OS-picked port and
// leave the saved port alone — the conflict may clear later.
let listener = match TcpListener::bind(("0.0.0.0", cfg.port)).await {
Ok(l) => l,
Err(e) => {
tracing::warn!(
"MCP saved port {} unavailable ({}); falling back to OS-picked port",
cfg.port,
e
);
TcpListener::bind("0.0.0.0:0").await?
}
};
let port = listener.local_addr()?.port();
let addr = SocketAddr::from(([127, 0, 0, 1], port));
let cancel_inner = cancel.clone();
let task = tokio::spawn(async move {
let _ = axum::serve(listener, router)
.with_graceful_shutdown(async move {
cancel_inner.cancelled().await;
})
.await;
});
tracing::info!("MCP server listening on http://{addr}/mcp");
Ok(RunningServer {
addr,
token,
cancel,
task,
})
}
pub fn stop_server(handle: &McpServerHandle) {
if let Some(srv) = handle.0.lock().take() {
srv.cancel.cancel();
srv.task.abort();
tracing::info!("MCP server stopped");
}
}
/// Mint a new bearer token, persist it, and return the new value. Caller is
/// responsible for restarting the server if it was running — the live auth
/// middleware captures the token by value at start time.
pub fn regenerate_token(app: &AppHandle) -> Result<String> {
let mut cfg = load_or_init_config(app)?;
cfg.token = generate_token();
save_config(app, &cfg)?;
Ok(cfg.token)
}