mcp_postgres/
server.rs

1use tokio::net::{TcpListener, TcpStream};
2use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
3use serde_json::{json, Value};
4use tracing::{error, warn};
5use std::sync::Arc;
6
7use crate::config::Config;
8use crate::errors::{MCPError, Result as MCPResult};
9use crate::metrics;
10use crate::pool::ConnectionPool;
11use crate::protocol::{JsonRpcRequest, JsonRpcResponse};
12use crate::actions;
13use once_cell::sync::Lazy;
14
15static TOOLS_LIST: Lazy<Value> = Lazy::new(|| {
16    let tools_json = include_str!("../tools.json");
17    let tools: Vec<Value> = serde_json::from_str(tools_json)
18        .expect("Failed to parse tools.json");
19    json!({ "tools": tools })
20});
21
22const BUFFER_CAPACITY: usize = 4096;
23const NEWLINE: &[u8] = b"\n";
24
25#[inline]
26#[cold]
27fn parse_error(msg: String) -> JsonRpcResponse {
28    let mcp_error = MCPError::ParseError(msg);
29    JsonRpcResponse::error(None, mcp_error.error_code(), mcp_error.to_string())
30}
31
32#[inline]
33fn parse_request(line: &str) -> Result<JsonRpcRequest, String> {
34    let trimmed = line.trim();
35    if trimmed.is_empty() {
36        return Err("Empty request".to_string());
37    }
38    serde_json::from_str::<JsonRpcRequest>(trimmed)
39        .map_err(|e| e.to_string())
40}
41
42pub struct MCPServer {
43    config: Config,
44    pool: Arc<ConnectionPool>,
45}
46
47impl MCPServer {
48    pub fn new(config: Config, pool: Arc<ConnectionPool>) -> Self {
49        Self { config, pool }
50    }
51
52    /// Run in stdio mode for MCP compatibility (Claude Desktop, etc.)
53    pub async fn run_stdio(&self) -> MCPResult<()> {
54        let stdin = tokio::io::stdin();
55        let mut reader = BufReader::with_capacity(BUFFER_CAPACITY, stdin);
56        let mut stdout = tokio::io::stdout();
57        let mut line = String::with_capacity(512);
58        let mut response_buf = Vec::with_capacity(65536);
59
60        loop {
61            line.clear();
62            match reader.read_line(&mut line).await {
63                Ok(0) => break,
64                Ok(_) => {
65                    process_one_line(&line, &self.pool, &self.config, &mut response_buf, &mut stdout).await?;
66                }
67                Err(e) => {
68                    error!("IO error: {}", e);
69                    break;
70                }
71            }
72        }
73        Ok(())
74    }
75
76    pub async fn run(&self) -> MCPResult<()> {
77        let addr = format!("{}:{}", self.config.server.host, self.config.server.port);
78        let listener = TcpListener::bind(&addr).await?;
79
80        tracing::info!("MCP server listening on {}", addr);
81
82        loop {
83            let (socket, peer_addr) = listener.accept().await?;
84
85            if let Err(e) = socket.set_nodelay(true) {
86                warn!("Failed to set TCP_NODELAY: {}", e);
87            }
88
89            let pool = Arc::clone(&self.pool);
90            let config = self.config.clone();
91
92            tokio::spawn(async move {
93                if let Err(e) = handle_client(socket, pool, config).await {
94                    error!("Client {} error: {}", peer_addr, e);
95                }
96            });
97        }
98    }
99}
100
101#[inline(never)]
102async fn handle_client(socket: TcpStream, pool: Arc<ConnectionPool>, config: Config) -> MCPResult<()> {
103    let (reader, mut writer) = socket.into_split();
104    let mut reader = BufReader::with_capacity(BUFFER_CAPACITY, reader);
105    let mut line = String::with_capacity(512);
106    let mut response_buf = Vec::with_capacity(65536);
107
108    loop {
109        line.clear();
110        match reader.read_line(&mut line).await {
111            Ok(0) => break,
112            Ok(_) => {
113                process_one_line(&line, &pool, &config, &mut response_buf, &mut writer).await?;
114            }
115            Err(e) => {
116                error!("IO error: {}", e);
117                break;
118            }
119        }
120    }
121
122    Ok(())
123}
124
125/// Core per-line processing shared by TCP and stdio transports.
126#[inline]
127async fn process_one_line<W: AsyncWriteExt + Unpin>(
128    line: &str,
129    pool: &Arc<ConnectionPool>,
130    config: &Config,
131    response_buf: &mut Vec<u8>,
132    writer: &mut W,
133) -> MCPResult<()> {
134    metrics::inc_requests();
135
136    let response = match parse_request(line) {
137        Ok(req) => match process_request(&req, pool, config).await {
138            Ok(result) => JsonRpcResponse::success(req.id, result),
139            Err(e) => {
140                metrics::inc_errors();
141                JsonRpcResponse::error(req.id, e.error_code(), e.to_string())
142            }
143        },
144        Err(e) => {
145            metrics::inc_errors();
146            parse_error(e)
147        }
148    };
149
150    response_buf.clear();
151    serde_json::to_writer(&mut *response_buf, &response)?;
152    response_buf.extend_from_slice(NEWLINE);
153
154    writer.write_all(response_buf).await?;
155    writer.flush().await?;
156    Ok(())
157}
158
159/// Process a JSON-RPC request (used by both TCP and HTTP transports)
160#[inline]
161pub async fn process_request(
162    req: &JsonRpcRequest,
163    pool: &Arc<ConnectionPool>,
164    config: &Config,
165) -> MCPResult<Value> {
166    match req.method.as_str() {
167        "initialize" => handle_initialize(req),
168        "tools/list" => handle_tools_list(),
169        "tools/call" => handle_tools_call(req, pool, config).await,
170        _ => Err(MCPError::MethodNotFound(req.method.clone())),
171    }
172}
173
174/// Public wrapper for HTTP handlers - returns complete JSON-RPC response
175pub async fn process_request_http(
176    req: &JsonRpcRequest,
177    pool: &Arc<ConnectionPool>,
178    config: &Config,
179) -> JsonRpcResponse {
180    metrics::inc_requests();
181
182    let response = match process_request(req, pool, config).await {
183        Ok(result) => JsonRpcResponse::success(req.id.clone(), result),
184        Err(e) => {
185            metrics::inc_errors();
186            JsonRpcResponse::error(req.id.clone(), e.error_code(), e.to_string())
187        }
188    };
189
190    response
191}
192
193#[inline]
194fn handle_initialize(_req: &JsonRpcRequest) -> MCPResult<Value> {
195    Ok(json!({
196        "protocolVersion": "2024-11-05",
197        "capabilities": {
198            "tools": {
199                "listChanged": false
200            },
201            "resources": {
202                "subscribe": false,
203                "listChanged": false
204            },
205            "prompts": {
206                "listChanged": false
207            }
208        },
209        "serverInfo": {
210            "name": "mcp-postgres",
211            "version": env!("CARGO_PKG_VERSION")
212        }
213    }))
214}
215
216#[inline]
217fn handle_tools_list() -> MCPResult<Value> {
218    Ok((*TOOLS_LIST).clone())
219}
220
221async fn handle_tools_call(
222    req: &JsonRpcRequest,
223    pool: &Arc<ConnectionPool>,
224    config: &Config,
225) -> MCPResult<Value> {
226    let tool_name = req
227        .params
228        .as_ref()
229        .and_then(|p| p.get("name").and_then(|v| v.as_str()))
230        .ok_or_else(|| MCPError::InvalidParams("Missing 'name' parameter".into()))?;
231
232    let tool_args = req.params.as_ref().and_then(|p| p.get("arguments"));
233
234    // Restricted mode check + unknown tool check BEFORE pool acquire
235    let write_tools: &[&str] = &[
236        "execute_insert", "execute_update", "execute_delete",
237        "async_execute_insert", "async_execute_update", "async_execute_delete",
238        "async_batch_insert", "async_batch_update", "async_batch_delete", "async_batch_insert_copy",
239        "create_table", "drop_table", "create_view", "drop_view", "alter_view", "create_schema", "drop_schema", "create_sequence", "drop_sequence", "alter_index", "backup_table", "create_index", "drop_index", "create_partition", "drop_partition",
240        "vacuum_analyze", "analyze_table", "reindex_table",
241        "reset_statistics", "truncate_table",
242    ];
243
244    if config.server.access_mode == crate::config::AccessMode::Restricted
245        && write_tools.contains(&tool_name)
246    {
247        return Err(MCPError::InvalidParams(format!(
248            "Operation '{tool_name}' is not allowed in restricted (read-only) mode"
249        )));
250    }
251
252    // Fast-path simple tools that don't need a DB connection
253    let no_db_tools: &[&str] = &["list_tables", "list_schemas", "show_constraints"];
254    if !no_db_tools.contains(&tool_name) {
255        // Verify tool exists before acquiring a connection
256        let tool_exists = matches!(tool_name,
257            "describe_table" | "list_triggers" | "list_indexes" | "execute_query" | "execute_insert"
258            | "execute_update" | "execute_delete" | "explain_query"
259            | "async_execute_insert" | "async_execute_update" | "async_execute_delete"
260            | "async_batch_insert" | "async_batch_update" | "async_batch_delete" | "async_batch_insert_copy"
261            | "create_table" | "drop_table" | "create_view" | "drop_view" | "alter_view" | "create_schema" | "drop_schema" | "create_sequence" | "drop_sequence" | "alter_index" | "create_index" | "list_partitions" | "drop_index" | "create_partition" | "drop_partition"
262            | "get_table_stats" | "get_index_stats" | "show_database_size"
263            | "show_table_size" | "get_cache_hit_ratio"
264            | "list_connections" | "show_current_user"
265            | "show_running_queries" | "show_connection_summary"
266            | "vacuum_analyze" | "analyze_table" | "reindex_table"
267            | "get_pg_stat_statements" | "reset_statistics" | "truncate_table"
268            | "list_users" | "list_user_privileges" | "list_role_memberships"
269            | "list_database_privileges" | "show_session_info"
270            | "show_all_settings" | "get_setting" | "show_memory_settings"
271            | "show_performance_settings" | "show_log_settings"
272            | "show_replication_status" | "list_replication_slots"
273            | "list_standby_servers" | "show_wal_info" | "show_base_backup_progress"
274            | "show_active_transactions" | "show_locks" | "show_waiting_locks"
275            | "show_transaction_isolation" | "show_deadlocks"
276            | "show_autocommit_status" | "show_transaction_timeout"
277            | "analyze_db_health" | "list_unused_indexes" | "list_duplicate_indexes"
278            | "show_vacuum_progress" | "get_object_details"
279        );
280        if !tool_exists {
281            return Err(method_not_found(tool_name));
282        }
283    }
284
285    // Acquire pool connection only for known tools
286    let client = pool.acquire().await?;
287
288    let result = match tool_name {
289        // Schema actions
290        "list_tables" => actions::schema::list_tables(&client, &tool_args).await,
291        "describe_table" => actions::schema::describe_table(&client, &tool_args).await,
292        "list_indexes" => actions::schema::list_indexes(&client, &tool_args).await,
293        "list_schemas" => actions::schema::list_schemas(&client, &tool_args).await,
294        "show_constraints" => actions::schema::show_constraints(&client, &tool_args).await,
295        "list_triggers" => actions::schema::list_triggers(&client, &tool_args).await,
296        "create_table" => actions::schema::create_table(&client, &tool_args).await,
297        "drop_table" => actions::schema::drop_table(&client, &tool_args).await,
298        "create_view" => actions::schema::create_view(&client, &tool_args).await,
299        "drop_view" => actions::schema::drop_view(&client, &tool_args).await,
300        "alter_view" => actions::schema::alter_view(&client, &tool_args).await,
301        "create_schema" => actions::schema::create_schema(&client, &tool_args).await,
302        "drop_schema" => actions::schema::drop_schema(&client, &tool_args).await,
303        "create_sequence" => actions::schema::create_sequence(&client, &tool_args).await,
304        "drop_sequence" => actions::schema::drop_sequence(&client, &tool_args).await,
305        "alter_index" => actions::schema::alter_index(&client, &tool_args).await,
306        "list_partitions" => actions::schema::list_partitions(&client, &tool_args).await,
307        "backup_table" => actions::schema::backup_table(&client, &tool_args).await,
308        "create_index" => actions::schema::create_index(&client, &tool_args).await,
309        "drop_index" => actions::schema::drop_index(&client, &tool_args).await,
310        "create_partition" => actions::schema::create_partition(&client, &tool_args).await,
311        "drop_partition" => actions::schema::drop_partition(&client, &tool_args).await,
312        // Query actions
313        "execute_query" => actions::query::execute_query(&client, &tool_args).await,
314        "execute_insert" => actions::query::execute_insert(&client, &tool_args).await,
315        "execute_update" => actions::query::execute_update(&client, &tool_args).await,
316        "execute_delete" => actions::query::execute_delete(&client, &tool_args).await,
317        "async_execute_insert" => actions::query::async_execute_insert(&client, &tool_args).await,
318        "async_execute_update" => actions::query::async_execute_update(&client, &tool_args).await,
319        "async_execute_delete" => actions::query::async_execute_delete(&client, &tool_args).await,
320        "explain_query" => actions::query::explain_query(&client, &tool_args).await,
321        // Batch operations
322        "async_batch_insert" => actions::batch::async_batch_insert(&client, &tool_args).await,
323        "async_batch_update" => actions::batch::async_batch_update(&client, &tool_args).await,
324        "async_batch_delete" => actions::batch::async_batch_delete(&client, &tool_args).await,
325        "async_batch_insert_copy" => actions::batch::async_batch_insert_copy(&client, &tool_args).await,
326        // Monitoring actions
327        "get_table_stats" => actions::monitoring::get_table_stats(&client, &tool_args).await,
328        "get_index_stats" => actions::monitoring::get_index_stats(&client, &tool_args).await,
329        "show_database_size" => actions::monitoring::show_database_size(&client, &tool_args).await,
330        "show_table_size" => actions::monitoring::show_table_size(&client, &tool_args).await,
331        "get_cache_hit_ratio" => actions::monitoring::get_cache_hit_ratio(&client, &tool_args).await,
332        // Connection actions
333        "list_connections" => actions::connections::list_connections(&client, &tool_args).await,
334        "show_current_user" => actions::connections::show_current_user(&client, &tool_args).await,
335        "show_running_queries" => actions::connections::show_running_queries(&client, &tool_args).await,
336        "show_connection_summary" => actions::connections::show_connection_summary(&client, &tool_args).await,
337        // Maintenance actions
338        "vacuum_analyze" => actions::maintenance::vacuum_analyze(&client, &tool_args).await,
339        "analyze_table" => actions::maintenance::analyze_table(&client, &tool_args).await,
340        "reindex_table" => actions::maintenance::reindex_table(&client, &tool_args).await,
341        "get_pg_stat_statements" => actions::maintenance::get_pg_stat_statements(&client, &tool_args).await,
342        "reset_statistics" => actions::maintenance::reset_statistics(&client, &tool_args).await,
343        "truncate_table" => actions::maintenance::truncate_table(&client, &tool_args).await,
344        // Security actions
345        "list_users" => actions::security::list_users(&client, &tool_args).await,
346        "list_user_privileges" => actions::security::list_user_privileges(&client, &tool_args).await,
347        "list_role_memberships" => actions::security::list_role_memberships(&client, &tool_args).await,
348        "list_database_privileges" => actions::security::list_database_privileges(&client, &tool_args).await,
349        "show_session_info" => actions::security::show_session_info(&client, &tool_args).await,
350        // Config actions
351        "show_all_settings" => actions::config::show_all_settings(&client, &tool_args).await,
352        "get_setting" => actions::config::get_setting(&client, &tool_args).await,
353        "show_memory_settings" => actions::config::show_memory_settings(&client, &tool_args).await,
354        "show_performance_settings" => actions::config::show_performance_settings(&client, &tool_args).await,
355        "show_log_settings" => actions::config::show_log_settings(&client, &tool_args).await,
356        // Replication actions
357        "show_replication_status" => actions::replication::show_replication_status(&client, &tool_args).await,
358        "list_replication_slots" => actions::replication::list_replication_slots(&client, &tool_args).await,
359        "list_standby_servers" => actions::replication::list_standby_servers(&client, &tool_args).await,
360        "show_wal_info" => actions::replication::show_wal_info(&client, &tool_args).await,
361        "show_base_backup_progress" => actions::replication::show_base_backup_progress(&client, &tool_args).await,
362        // Transaction actions
363        "show_active_transactions" => actions::transactions::show_active_transactions(&client, &tool_args).await,
364        "show_locks" => actions::transactions::show_locks(&client, &tool_args).await,
365        "show_waiting_locks" => actions::transactions::show_waiting_locks(&client, &tool_args).await,
366        "show_transaction_isolation" => actions::transactions::show_transaction_isolation(&client, &tool_args).await,
367        "show_deadlocks" => actions::transactions::show_deadlocks(&client, &tool_args).await,
368        "show_autocommit_status" => actions::transactions::show_autocommit_status(&client, &tool_args).await,
369        "show_transaction_timeout" => actions::transactions::show_transaction_timeout(&client, &tool_args).await,
370        // Health actions
371        "analyze_db_health" => actions::health::analyze_db_health(&client, &tool_args).await,
372        "list_unused_indexes" => actions::health::list_unused_indexes(&client, &tool_args).await,
373        "list_duplicate_indexes" => actions::health::list_duplicate_indexes(&client, &tool_args).await,
374        "show_vacuum_progress" => actions::health::show_vacuum_progress(&client, &tool_args).await,
375        // Enhanced schema
376        "get_object_details" => actions::schema::get_object_details(&client, &tool_args).await,
377        tool => Err(method_not_found(tool)),
378    };
379
380    pool.release(client);
381    result
382}
383
384#[cold]
385fn method_not_found(name: &str) -> MCPError {
386    MCPError::MethodNotFound(name.to_string())
387}
388
389#[cfg(test)]
390mod tests {
391    use super::*;
392
393    #[test]
394    fn test_parse_valid_request() {
395        let line = r#"{"jsonrpc":"2.0","method":"initialize","id":1}"#;
396        let req = parse_request(line).unwrap();
397        assert_eq!(req.method, "initialize");
398        assert_eq!(req.id, Some(Value::Number(1.into())));
399    }
400
401    #[test]
402    fn test_parse_request_with_trailing_newline() {
403        let line = r#"{"jsonrpc":"2.0","method":"tools/list","id":2}"#;
404        let req = parse_request(line).unwrap();
405        assert_eq!(req.method, "tools/list");
406    }
407
408    #[test]
409    fn test_parse_request_with_whitespace() {
410        let line = "  {\"jsonrpc\":\"2.0\",\"method\":\"ping\",\"id\":3}  ";
411        let req = parse_request(line).unwrap();
412        assert_eq!(req.method, "ping");
413    }
414
415    #[test]
416    fn test_parse_empty_request() {
417        let err = parse_request("").unwrap_err();
418        assert_eq!(err, "Empty request");
419    }
420
421    #[test]
422    fn test_parse_whitespace_only() {
423        let err = parse_request("   \n  ").unwrap_err();
424        assert_eq!(err, "Empty request");
425    }
426
427    #[test]
428    fn test_parse_invalid_json() {
429        let err = parse_request("{invalid}").unwrap_err();
430        assert!(!err.is_empty(), "Invalid JSON should produce an error message");
431    }
432
433    #[test]
434    fn test_parse_missing_method() {
435        let err = parse_request(r#"{"jsonrpc":"2.0","id":1}"#).unwrap_err();
436        assert!(err.contains("method"));
437    }
438
439    #[test]
440    fn test_parse_wrong_version() {
441        let req = parse_request(r#"{"jsonrpc":"1.0","method":"init","id":1}"#).unwrap();
442        assert_eq!(req.jsonrpc, "1.0");
443    }
444
445    #[test]
446    fn test_method_not_found_error() {
447        let err = method_not_found("test_tool");
448        assert_eq!(err.error_code(), -32601);
449        assert!(err.to_string().contains("test_tool"));
450    }
451
452    #[test]
453    fn test_tools_list_static() {
454        let list = &*TOOLS_LIST;
455        let tools = list.get("tools").and_then(|v| v.as_array());
456        assert!(tools.is_some(), "TOOLS_LIST should contain a tools array");
457        assert!(!tools.unwrap().is_empty(), "Tools list should not be empty");
458    }
459
460    #[test]
461    fn test_process_request_method_dispatch() {
462        // Verify that process_request handles the dispatch correctly
463        // by testing the match on method strings — this is a compilation/coverage test
464        let _req = JsonRpcRequest {
465            jsonrpc: "2.0".to_string(),
466            method: "nonexistent".to_string(),
467            params: None,
468            id: Some(Value::Number(1.into())),
469        };
470        // We can't run process_request without a pool, but we can verify the fallback path
471        // acts as expected through separate unit tests on the dispatch logic
472    }
473
474    #[test]
475    fn test_handle_initialize_response() {
476        let req = JsonRpcRequest {
477            jsonrpc: "2.0".to_string(),
478            method: "initialize".to_string(),
479            params: None,
480            id: Some(Value::Number(1.into())),
481        };
482        let result = handle_initialize(&req).unwrap();
483        assert_eq!(result["protocolVersion"], "2024-11-05");
484        assert!(result["capabilities"]["tools"]["listChanged"].is_boolean());
485        assert_eq!(result["serverInfo"]["version"], env!("CARGO_PKG_VERSION"));
486    }
487}
mcp_postgres/server.rs

mcp_postgres/
server.rs
