rust_web_server/mcp/
mod.rs

1//! Model Context Protocol (MCP) server — HTTP Streamable HTTP transport.
2//!
3//! [`McpServer`] implements [`Application`] so it can be passed directly to
4//! [`Server::run`]. Unmatched requests fall through to the built-in [`App`]
5//! controller chain (static files, health probes, etc.).
6//!
7//! # Quick start
8//!
9//! ```rust,no_run
10//! use rust_web_server::server::Server;
11//! use rust_web_server::mcp::{McpServer, McpContent, PromptMessage};
12//! # fn main() {
13//! let mcp = McpServer::new("my-server", "1.0")
14//!     // A tool: callable by the AI, like a function
15//!     .tool(
16//!         "echo",
17//!         "Echo text back",
18//!         r#"{"type":"object","properties":{"text":{"type":"string"}},"required":["text"]}"#,
19//!         |args| {
20//!             let text = rust_web_server::mcp::extract_arg(args, "text")
21//!                 .unwrap_or_else(|| "(nothing)".to_string());
22//!             Ok(McpContent::text(text))
23//!         },
24//!     )
25//!     // A resource: data the AI can read by URI
26//!     .resource(
27//!         "docs://{topic}",
28//!         "Documentation",
29//!         "Return documentation for a topic",
30//!         |uri| Ok(McpContent::text(format!("Documentation for: {uri}"))),
31//!     )
32//!     // A prompt template: reusable message structures
33//!     .prompt(
34//!         "summarize",
35//!         "Summarize the given text",
36//!         |args| {
37//!             let text = rust_web_server::mcp::extract_arg(args, "text")
38//!                 .unwrap_or_else(|| "some text".to_string());
39//!             Ok(vec![PromptMessage::user(format!("Please summarize: {text}"))])
40//!         },
41//!     );
42//!
43//! // let (listener, pool) = Server::setup().unwrap();
44//! // Server::run(listener, pool, mcp);
45//! # }
46//! ```
47//!
48//! # MCP endpoint
49//!
50//! All JSON-RPC messages are sent as `POST /mcp` (override with [`.at()`](McpServer::at)).
51//! The server implements the [MCP 2024-11-05 specification](https://spec.modelcontextprotocol.io).
52//!
53//! # Environment variables
54//!
55//! None — configure the server programmatically via the builder.
56
57mod json_rpc;
58
59#[cfg(test)]
60mod tests;
61
62use std::sync::Arc;
63
64use crate::app::App;
65use crate::application::Application;
66use crate::core::New;
67use crate::header::Header;
68use crate::mime_type::MimeType;
69use crate::range::Range;
70use crate::request::Request;
71use crate::response::{Response, STATUS_CODE_REASON_PHRASE};
72use crate::server::ConnectionInfo;
73
74const PROTOCOL_VERSION: &str = "2024-11-05";
75
76// ── public content types ──────────────────────────────────────────────────────
77
78/// Content returned by tool and resource handlers.
79///
80/// Create with [`McpContent::text`] (plain text or JSON strings) or
81/// [`McpContent::json`] (marks MIME type as `application/json`).
82#[derive(Clone, Debug)]
83pub struct McpContent {
84    /// Always `"text"` in the current MCP spec.
85    pub kind: &'static str,
86    /// The content string.
87    pub text: String,
88    /// Optional MIME type override (default `"text/plain"`).
89    pub mime_type: Option<String>,
90}
91
92impl McpContent {
93    /// Plain-text content.
94    pub fn text(s: impl Into<String>) -> Self {
95        McpContent { kind: "text", text: s.into(), mime_type: None }
96    }
97
98    /// JSON content — sets `mimeType` to `application/json`.
99    pub fn json(s: impl Into<String>) -> Self {
100        McpContent { kind: "text", text: s.into(), mime_type: Some("application/json".to_string()) }
101    }
102
103    fn to_content_json(&self) -> String {
104        let escaped = json_escape(&self.text);
105        format!(r#"{{"type":"{}","text":"{}"}}"#, self.kind, escaped)
106    }
107
108    fn mime(&self) -> &str {
109        self.mime_type.as_deref().unwrap_or("text/plain")
110    }
111}
112
113/// A single message in a prompt response.
114#[derive(Clone, Debug)]
115pub struct PromptMessage {
116    /// `"user"` or `"assistant"`.
117    pub role: &'static str,
118    /// The message content.
119    pub content: McpContent,
120}
121
122impl PromptMessage {
123    /// Build a user-role message.
124    pub fn user(text: impl Into<String>) -> Self {
125        PromptMessage { role: "user", content: McpContent::text(text) }
126    }
127
128    /// Build an assistant-role message.
129    pub fn assistant(text: impl Into<String>) -> Self {
130        PromptMessage { role: "assistant", content: McpContent::text(text) }
131    }
132
133    fn to_json(&self) -> String {
134        format!(
135            r#"{{"role":"{}","content":{}}}"#,
136            self.role,
137            self.content.to_content_json(),
138        )
139    }
140}
141
142/// Argument definition for a prompt template.
143#[derive(Clone)]
144pub struct PromptArgDef {
145    pub name: String,
146    pub description: String,
147    pub required: bool,
148}
149
150impl PromptArgDef {
151    pub fn required(name: impl Into<String>, description: impl Into<String>) -> Self {
152        PromptArgDef { name: name.into(), description: description.into(), required: true }
153    }
154
155    pub fn optional(name: impl Into<String>, description: impl Into<String>) -> Self {
156        PromptArgDef { name: name.into(), description: description.into(), required: false }
157    }
158}
159
160// ── internal handler registrations ───────────────────────────────────────────
161
162type ToolFn     = Arc<dyn Fn(&str) -> Result<McpContent, String>    + Send + Sync>;
163type ResourceFn = Arc<dyn Fn(&str) -> Result<McpContent, String>    + Send + Sync>;
164type PromptFn   = Arc<dyn Fn(&str) -> Result<Vec<PromptMessage>, String> + Send + Sync>;
165
166#[derive(Clone)]
167struct ToolDef {
168    name: String,
169    description: String,
170    input_schema: String,
171    handler: ToolFn,
172}
173
174#[derive(Clone)]
175struct ResourceDef {
176    uri_template: String,
177    name: String,
178    description: String,
179    handler: ResourceFn,
180}
181
182#[derive(Clone)]
183struct PromptDef {
184    name: String,
185    description: String,
186    arguments: Vec<PromptArgDef>,
187    handler: PromptFn,
188}
189
190// ── McpServer ─────────────────────────────────────────────────────────────────
191
192/// An HTTP server that implements the MCP 2024-11-05 protocol.
193///
194/// Register tools, resources, and prompts with the builder methods, then pass
195/// the server to [`Server::run`] (or [`Server::run_tls`]) as an [`Application`].
196/// Requests that do not match the MCP endpoint fall through to the built-in
197/// [`App`] controller chain.
198#[derive(Clone)]
199pub struct McpServer {
200    server_name: String,
201    server_version: String,
202    path: String,
203    tools: Vec<ToolDef>,
204    resources: Vec<ResourceDef>,
205    prompts: Vec<PromptDef>,
206    fallback: Option<Arc<dyn Application + Send + Sync>>,
207    auth_token: Option<String>,
208}
209
210impl McpServer {
211    /// Create a new `McpServer`.  The default MCP endpoint is `POST /mcp`.
212    pub fn new(name: impl Into<String>, version: impl Into<String>) -> Self {
213        McpServer {
214            server_name: name.into(),
215            server_version: version.into(),
216            path: "/mcp".to_string(),
217            tools: vec![],
218            resources: vec![],
219            prompts: vec![],
220            fallback: None,
221            auth_token: None,
222        }
223    }
224
225    /// Require a bearer token on every request to the MCP endpoint.
226    ///
227    /// The client must send `Authorization: Bearer <token>`. Requests with a
228    /// missing or wrong token receive `401 Unauthorized` before any JSON-RPC
229    /// processing occurs.
230    ///
231    /// Store the token in an environment variable — never hard-code it:
232    ///
233    /// ```rust,no_run
234    /// use rust_web_server::app::App;
235    /// use rust_web_server::core::New;
236    ///
237    /// let app = App::new()
238    ///     .mcp("my-server", "1.0")
239    ///     .require_bearer(std::env::var("MCP_TOKEN").expect("MCP_TOKEN not set"));
240    /// ```
241    ///
242    /// Claude Desktop config:
243    /// ```json
244    /// { "mcpServers": { "my-server": {
245    ///     "url": "http://localhost:7878/mcp",
246    ///     "headers": { "Authorization": "Bearer <token>" }
247    /// }}}
248    /// ```
249    pub fn require_bearer(mut self, token: impl Into<String>) -> Self {
250        self.auth_token = Some(token.into());
251        self
252    }
253
254    /// Wrap an existing [`Application`] so that non-MCP requests are forwarded
255    /// to it instead of the built-in [`App`].
256    ///
257    /// Use this when your existing server has custom routes, state, or
258    /// middleware that you want to keep alongside the MCP endpoint:
259    ///
260    /// ```rust,no_run
261    /// use rust_web_server::app::App;
262    /// use rust_web_server::mcp::{McpServer, McpContent};
263    /// use rust_web_server::response::{Response, STATUS_CODE_REASON_PHRASE};
264    /// use rust_web_server::test_client::TestClient;
265    ///
266    /// let existing_app = App::with_state(42u32)
267    ///     .get("/api/hello", |_req, _params, _conn, _state| {
268    ///         Response::get_response(&STATUS_CODE_REASON_PHRASE.n200_ok, None, None)
269    ///     });
270    ///
271    /// let server = McpServer::new("my-app", "1.0")
272    ///     .tool("ping", "Ping", "{}", |_| Ok(McpContent::text("pong")))
273    ///     .wrap(existing_app);
274    ///
275    /// // Both /mcp and /api/hello are now handled by the same server.
276    /// let client = TestClient::new(server);
277    /// ```
278    pub fn wrap(mut self, app: impl Application + Send + Sync + 'static) -> Self {
279        self.fallback = Some(Arc::new(app));
280        self
281    }
282
283    /// Override the HTTP path for the MCP endpoint (default `"/mcp"`).
284    pub fn at(mut self, path: impl Into<String>) -> Self {
285        self.path = path.into();
286        self
287    }
288
289    /// Register a callable tool.
290    ///
291    /// - `name` — tool identifier (snake_case recommended)
292    /// - `description` — human-readable description shown to the AI
293    /// - `input_schema` — JSON Schema object for the tool's arguments
294    /// - `handler` — closure receiving the raw `arguments` JSON string
295    ///
296    /// The handler returns [`McpContent`] on success or an error string.  An
297    /// error is returned to the client as `isError: true` (not a protocol error).
298    pub fn tool<F>(mut self, name: &str, description: &str, input_schema: &str, handler: F) -> Self
299    where
300        F: Fn(&str) -> Result<McpContent, String> + Send + Sync + 'static,
301    {
302        self.tools.push(ToolDef {
303            name: name.to_string(),
304            description: description.to_string(),
305            input_schema: input_schema.to_string(),
306            handler: Arc::new(handler),
307        });
308        self
309    }
310
311    /// Register a readable resource.
312    ///
313    /// `uri_template` uses `{param}` placeholders, e.g. `"user://{id}"`.
314    /// The handler receives the full concrete URI string.
315    pub fn resource<F>(mut self, uri_template: &str, name: &str, description: &str, handler: F) -> Self
316    where
317        F: Fn(&str) -> Result<McpContent, String> + Send + Sync + 'static,
318    {
319        self.resources.push(ResourceDef {
320            uri_template: uri_template.to_string(),
321            name: name.to_string(),
322            description: description.to_string(),
323            handler: Arc::new(handler),
324        });
325        self
326    }
327
328    /// Register a prompt template.
329    ///
330    /// The handler receives the raw `arguments` JSON string and returns a
331    /// list of [`PromptMessage`] values.
332    pub fn prompt<F>(mut self, name: &str, description: &str, handler: F) -> Self
333    where
334        F: Fn(&str) -> Result<Vec<PromptMessage>, String> + Send + Sync + 'static,
335    {
336        self.prompts.push(PromptDef {
337            name: name.to_string(),
338            description: description.to_string(),
339            arguments: vec![],
340            handler: Arc::new(handler),
341        });
342        self
343    }
344
345    /// Register a prompt template with explicit argument definitions.
346    pub fn prompt_with_args<F>(
347        mut self,
348        name: &str,
349        description: &str,
350        args: Vec<PromptArgDef>,
351        handler: F,
352    ) -> Self
353    where
354        F: Fn(&str) -> Result<Vec<PromptMessage>, String> + Send + Sync + 'static,
355    {
356        self.prompts.push(PromptDef {
357            name: name.to_string(),
358            description: description.to_string(),
359            arguments: args,
360            handler: Arc::new(handler),
361        });
362        self
363    }
364
365    // ── request dispatch ──────────────────────────────────────────────────────
366
367    /// Process a raw JSON-RPC body and return an HTTP response.
368    pub fn handle_request(&self, body: &str) -> Response {
369        let method = match json_rpc::extract_str(body, "method") {
370            Some(m) => m,
371            None => return rpc_error(None, json_rpc::INVALID_REQUEST, "Missing method"),
372        };
373
374        let id = json_rpc::extract_id(body);
375
376        // Notifications have no `id` — acknowledge with 202 and no body.
377        if method == "notifications/initialized" || (id.is_none() && method != "ping") {
378            return no_content();
379        }
380
381        let result: Result<String, (i32, String)> = match method.as_str() {
382            "initialize"     => self.do_initialize(),
383            "ping"           => Ok("{}".to_string()),
384            "tools/list"     => self.do_tools_list(),
385            "tools/call"     => self.do_tools_call(body),
386            "resources/list" => self.do_resources_list(),
387            "resources/read" => self.do_resources_read(body),
388            "prompts/list"   => self.do_prompts_list(),
389            "prompts/get"    => self.do_prompts_get(body),
390            _                => Err((json_rpc::METHOD_NOT_FOUND, format!("Unknown method: {method}"))),
391        };
392
393        let id_str = id.as_deref().unwrap_or("null");
394
395        match result {
396            Ok(result_json) => json_response(&format!(
397                r#"{{"jsonrpc":"2.0","result":{result_json},"id":{id_str}}}"#
398            )),
399            Err((code, msg)) => {
400                let escaped = json_escape(&msg);
401                json_response(&format!(
402                    r#"{{"jsonrpc":"2.0","error":{{"code":{code},"message":"{escaped}"}},"id":{id_str}}}"#
403                ))
404            }
405        }
406    }
407
408    // ── method handlers ───────────────────────────────────────────────────────
409
410    fn do_initialize(&self) -> Result<String, (i32, String)> {
411        let caps = format!(
412            r#"{{"tools":{{"listChanged":false}},"resources":{{"subscribe":false,"listChanged":false}},"prompts":{{"listChanged":false}}}}"#
413        );
414        Ok(format!(
415            r#"{{"protocolVersion":"{PROTOCOL_VERSION}","capabilities":{caps},"serverInfo":{{"name":"{}","version":"{}"}}}}"#,
416            json_escape(&self.server_name),
417            json_escape(&self.server_version),
418        ))
419    }
420
421    fn do_tools_list(&self) -> Result<String, (i32, String)> {
422        let items: Vec<String> = self.tools.iter().map(|t| {
423            format!(
424                r#"{{"name":"{}","description":"{}","inputSchema":{}}}"#,
425                json_escape(&t.name),
426                json_escape(&t.description),
427                t.input_schema,
428            )
429        }).collect();
430        Ok(format!(r#"{{"tools":[{}]}}"#, items.join(",")))
431    }
432
433    fn do_tools_call(&self, body: &str) -> Result<String, (i32, String)> {
434        let params = json_rpc::extract_raw(body, "params")
435            .ok_or((json_rpc::INVALID_PARAMS, "Missing params".to_string()))?;
436        let name = json_rpc::extract_str(&params, "name")
437            .ok_or((json_rpc::INVALID_PARAMS, "Missing tool name".to_string()))?;
438        let args = json_rpc::extract_raw(&params, "arguments")
439            .unwrap_or_else(|| "{}".to_string());
440
441        let tool = self.tools.iter().find(|t| t.name == name)
442            .ok_or_else(|| (json_rpc::INVALID_PARAMS, format!("Unknown tool: {name}")))?;
443
444        match (tool.handler)(&args) {
445            Ok(c) => Ok(format!(
446                r#"{{"content":[{}],"isError":false}}"#,
447                c.to_content_json(),
448            )),
449            Err(e) => {
450                let escaped = json_escape(&e);
451                Ok(format!(
452                    r#"{{"content":[{{"type":"text","text":"{escaped}"}}],"isError":true}}"#
453                ))
454            }
455        }
456    }
457
458    fn do_resources_list(&self) -> Result<String, (i32, String)> {
459        let items: Vec<String> = self.resources.iter().map(|r| {
460            format!(
461                r#"{{"uri":"{}","name":"{}","description":"{}","mimeType":"text/plain"}}"#,
462                json_escape(&r.uri_template),
463                json_escape(&r.name),
464                json_escape(&r.description),
465            )
466        }).collect();
467        Ok(format!(r#"{{"resources":[{}]}}"#, items.join(",")))
468    }
469
470    fn do_resources_read(&self, body: &str) -> Result<String, (i32, String)> {
471        let params = json_rpc::extract_raw(body, "params")
472            .ok_or((json_rpc::INVALID_PARAMS, "Missing params".to_string()))?;
473        let uri = json_rpc::extract_str(&params, "uri")
474            .ok_or((json_rpc::INVALID_PARAMS, "Missing uri".to_string()))?;
475
476        let resource = self.resources.iter().find(|r| uri_matches(&r.uri_template, &uri))
477            .ok_or_else(|| (json_rpc::INVALID_PARAMS, format!("Resource not found: {uri}")))?;
478
479        match (resource.handler)(&uri) {
480            Ok(c) => {
481                let text_esc = json_escape(&c.text);
482                let uri_esc  = json_escape(&uri);
483                Ok(format!(
484                    r#"{{"contents":[{{"uri":"{uri_esc}","mimeType":"{}","text":"{text_esc}"}}]}}"#,
485                    c.mime(),
486                ))
487            }
488            Err(e) => Err((json_rpc::INVALID_PARAMS, e)),
489        }
490    }
491
492    fn do_prompts_list(&self) -> Result<String, (i32, String)> {
493        let items: Vec<String> = self.prompts.iter().map(|p| {
494            let arg_defs: Vec<String> = p.arguments.iter().map(|a| {
495                format!(
496                    r#"{{"name":"{}","description":"{}","required":{}}}"#,
497                    json_escape(&a.name),
498                    json_escape(&a.description),
499                    a.required,
500                )
501            }).collect();
502            format!(
503                r#"{{"name":"{}","description":"{}","arguments":[{}]}}"#,
504                json_escape(&p.name),
505                json_escape(&p.description),
506                arg_defs.join(","),
507            )
508        }).collect();
509        Ok(format!(r#"{{"prompts":[{}]}}"#, items.join(",")))
510    }
511
512    fn do_prompts_get(&self, body: &str) -> Result<String, (i32, String)> {
513        let params = json_rpc::extract_raw(body, "params")
514            .ok_or((json_rpc::INVALID_PARAMS, "Missing params".to_string()))?;
515        let name = json_rpc::extract_str(&params, "name")
516            .ok_or((json_rpc::INVALID_PARAMS, "Missing prompt name".to_string()))?;
517        let args = json_rpc::extract_raw(&params, "arguments")
518            .unwrap_or_else(|| "{}".to_string());
519
520        let prompt = self.prompts.iter().find(|p| p.name == name)
521            .ok_or_else(|| (json_rpc::INVALID_PARAMS, format!("Unknown prompt: {name}")))?;
522
523        match (prompt.handler)(&args) {
524            Ok(msgs) => {
525                let msg_jsons: Vec<String> = msgs.iter().map(|m| m.to_json()).collect();
526                Ok(format!(
527                    r#"{{"description":"{}","messages":[{}]}}"#,
528                    json_escape(&prompt.description),
529                    msg_jsons.join(","),
530                ))
531            }
532            Err(e) => Err((json_rpc::INVALID_PARAMS, e)),
533        }
534    }
535}
536
537// ── Application ───────────────────────────────────────────────────────────────
538
539impl Application for McpServer {
540    fn execute(&self, request: &Request, connection: &ConnectionInfo) -> Result<Response, String> {
541        if request.request_uri == self.path {
542            // Check bearer token before processing any MCP request.
543            if let Some(expected) = &self.auth_token {
544                let provided = request.headers.iter()
545                    .find(|h| h.name.eq_ignore_ascii_case("authorization"))
546                    .map(|h| h.value.as_str())
547                    .unwrap_or("");
548                let bearer = provided.strip_prefix("Bearer ").unwrap_or("");
549                if bearer != expected.as_str() {
550                    return Ok(unauthorized());
551                }
552            }
553
554            return Ok(match request.method.as_str() {
555                "POST" => {
556                    let body = std::str::from_utf8(&request.body).unwrap_or("");
557                    self.handle_request(body)
558                }
559                "OPTIONS" => {
560                    // CORS preflight for browser-based MCP clients
561                    let mut r = Response::new();
562                    r.status_code = *STATUS_CODE_REASON_PHRASE.n200_ok.status_code;
563                    r.reason_phrase = STATUS_CODE_REASON_PHRASE.n200_ok.reason_phrase.to_string();
564                    r.headers.push(Header {
565                        name: "Allow".to_string(),
566                        value: "POST, OPTIONS".to_string(),
567                    });
568                    r
569                }
570                _ => {
571                    let mut r = Response::new();
572                    r.status_code = *STATUS_CODE_REASON_PHRASE.n405_method_not_allowed.status_code;
573                    r.reason_phrase = STATUS_CODE_REASON_PHRASE.n405_method_not_allowed.reason_phrase.to_string();
574                    r.headers.push(Header {
575                        name: "Allow".to_string(),
576                        value: "POST, OPTIONS".to_string(),
577                    });
578                    r.content_range_list = vec![Range::get_content_range(
579                        b"MCP endpoint only accepts POST".to_vec(),
580                        MimeType::TEXT_PLAIN.to_string(),
581                    )];
582                    r
583                }
584            });
585        }
586
587        // Not an MCP path — fall through to the wrapped app (or built-in App).
588        match &self.fallback {
589            Some(app) => app.execute(request, connection),
590            None      => App::new().execute(request, connection),
591        }
592    }
593}
594
595// ── public helper ─────────────────────────────────────────────────────────────
596
597/// Extract a string argument from a tool/prompt `arguments` JSON object.
598///
599/// ```rust
600/// use rust_web_server::mcp::extract_arg;
601/// assert_eq!(extract_arg(r#"{"text":"hello"}"#, "text").as_deref(), Some("hello"));
602/// assert_eq!(extract_arg(r#"{}"#, "missing"), None);
603/// ```
604pub fn extract_arg(arguments: &str, name: &str) -> Option<String> {
605    json_rpc::extract_str(arguments, name)
606}
607
608// ── internal helpers ──────────────────────────────────────────────────────────
609
610fn json_response(body: &str) -> Response {
611    let mut r = Response::new();
612    r.status_code = *STATUS_CODE_REASON_PHRASE.n200_ok.status_code;
613    r.reason_phrase = STATUS_CODE_REASON_PHRASE.n200_ok.reason_phrase.to_string();
614    r.content_range_list = vec![Range::get_content_range(
615        body.as_bytes().to_vec(),
616        MimeType::APPLICATION_JSON.to_string(),
617    )];
618    r
619}
620
621fn no_content() -> Response {
622    let mut r = Response::new();
623    r.status_code = *STATUS_CODE_REASON_PHRASE.n202_accepted.status_code;
624    r.reason_phrase = STATUS_CODE_REASON_PHRASE.n202_accepted.reason_phrase.to_string();
625    r
626}
627
628fn unauthorized() -> Response {
629    let mut r = Response::new();
630    r.status_code = *STATUS_CODE_REASON_PHRASE.n401_unauthorized.status_code;
631    r.reason_phrase = STATUS_CODE_REASON_PHRASE.n401_unauthorized.reason_phrase.to_string();
632    r.headers.push(Header {
633        name: "WWW-Authenticate".to_string(),
634        value: "Bearer".to_string(),
635    });
636    r.content_range_list = vec![Range::get_content_range(
637        b"Unauthorized".to_vec(),
638        MimeType::TEXT_PLAIN.to_string(),
639    )];
640    r
641}
642
643fn rpc_error(id: Option<&str>, code: i32, message: &str) -> Response {
644    let id_str  = id.unwrap_or("null");
645    let escaped = json_escape(message);
646    json_response(&format!(
647        r#"{{"jsonrpc":"2.0","error":{{"code":{code},"message":"{escaped}"}},"id":{id_str}}}"#
648    ))
649}
650
651pub(crate) fn json_escape(s: &str) -> String {
652    let mut out = String::with_capacity(s.len() + 4);
653    for ch in s.chars() {
654        match ch {
655            '"'  => out.push_str("\\\""),
656            '\\' => out.push_str("\\\\"),
657            '\n' => out.push_str("\\n"),
658            '\r' => out.push_str("\\r"),
659            '\t' => out.push_str("\\t"),
660            c if (c as u32) < 0x20 => { let _ = std::fmt::Write::write_fmt(&mut out, format_args!("\\u{:04x}", c as u32)); }
661            c    => out.push(c),
662        }
663    }
664    out
665}
666
667fn uri_matches(template: &str, uri: &str) -> bool {
668    // Template `"user://{id}"` matches any URI starting with `"user://"`.
669    match template.find('{') {
670        Some(pos) => uri.starts_with(&template[..pos]),
671        None      => template == uri,
672    }
673}
rust_web_server/mcp/mod.rs

rust_web_server/mcp/
mod.rs
