Plugins! (#420)

* Some queries

* Plugins!!

* cleanup

* actual names

* the actual plugins

* comment

* fix tests

* Tests

* unused errors

* Increase reaper rate to actually enforce settings

* ok

src/query_router.rs

@@ -6,13 +6,16 @@ use once_cell::sync::OnceCell;
 use regex::{Regex, RegexSet};
 use sqlparser::ast::Statement::{Query, StartTransaction};
 use sqlparser::ast::{
-    BinaryOperator, Expr, Ident, JoinConstraint, JoinOperator, SetExpr, TableFactor, Value,
+    BinaryOperator, Expr, Ident, JoinConstraint, JoinOperator, SetExpr, Statement, TableFactor,
+    Value,
 };
 use sqlparser::dialect::PostgreSqlDialect;
 use sqlparser::parser::Parser;
 
 use crate::config::Role;
+use crate::errors::Error;
 use crate::messages::BytesMutReader;
+use crate::plugins::{Intercept, Plugin, PluginOutput, TableAccess};
 use crate::pool::PoolSettings;
 use crate::sharding::Sharder;
 
@@ -129,6 +132,10 @@ impl QueryRouter {
         self.pool_settings = pool_settings;
     }
 
+    pub fn pool_settings<'a>(&'a self) -> &'a PoolSettings {
+        &self.pool_settings
+    }
+
     /// Try to parse a command and execute it.
     pub fn try_execute_command(&mut self, message_buffer: &BytesMut) -> Option<(Command, String)> {
         let mut message_cursor = Cursor::new(message_buffer);
@@ -324,10 +331,7 @@ impl QueryRouter {
         Some((command, value))
     }
 
-    /// Try to infer which server to connect to based on the contents of the query.
-    pub fn infer(&mut self, message: &BytesMut) -> bool {
-        debug!("Inferring role");
-
+    pub fn parse(message: &BytesMut) -> Result<Vec<sqlparser::ast::Statement>, Error> {
         let mut message_cursor = Cursor::new(message);
 
         let code = message_cursor.get_u8() as char;
@@ -353,28 +357,29 @@ impl QueryRouter {
                 query
             }
 
-            _ => return false,
+            _ => return Err(Error::UnsupportedStatement),
         };
 
-        let ast = match Parser::parse_sql(&PostgreSqlDialect {}, &query) {
-            Ok(ast) => ast,
+        match Parser::parse_sql(&PostgreSqlDialect {}, &query) {
+            Ok(ast) => Ok(ast),
             Err(err) => {
-                // SELECT ... FOR UPDATE won't get parsed correctly.
                 debug!("{}: {}", err, query);
-                self.active_role = Some(Role::Primary);
-                return false;
+                Err(Error::QueryRouterParserError(err.to_string()))
             }
-        };
+        }
+    }
 
-        debug!("AST: {:?}", ast);
+    /// Try to infer which server to connect to based on the contents of the query.
+    pub fn infer(&mut self, ast: &Vec<sqlparser::ast::Statement>) -> Result<(), Error> {
+        debug!("Inferring role");
 
         if ast.is_empty() {
             // That's weird, no idea, let's go to primary
             self.active_role = Some(Role::Primary);
-            return false;
+            return Err(Error::QueryRouterParserError("empty query".into()));
         }
 
-        for q in &ast {
+        for q in ast {
             match q {
                 // All transactions go to the primary, probably a write.
                 StartTransaction { .. } => {
@@ -418,7 +423,7 @@ impl QueryRouter {
             };
         }
 
-        true
+        Ok(())
     }
 
     /// Parse the shard number from the Bind message
@@ -783,6 +788,32 @@ impl QueryRouter {
         }
     }
 
+    /// Add your plugins here and execute them.
+    pub async fn execute_plugins(&self, ast: &Vec<Statement>) -> Result<PluginOutput, Error> {
+        if let Some(plugins) = &self.pool_settings.plugins {
+            if plugins.contains(&String::from("intercept")) {
+                let mut intercept = Intercept {};
+                let result = intercept.run(&self, ast).await;
+
+                if let Ok(PluginOutput::Intercept(output)) = result {
+                    return Ok(PluginOutput::Intercept(output));
+                }
+            }
+
+            if plugins.contains(&String::from("pg_table_access")) {
+                let mut table_access = TableAccess {
+                    forbidden_tables: vec![String::from("pg_database"), String::from("pg_roles")],
+                };
+
+                if let Ok(PluginOutput::Deny(error)) = table_access.run(&self, ast).await {
+                    return Ok(PluginOutput::Deny(error));
+                }
+            }
+        }
+
+        Ok(PluginOutput::Allow)
+    }
+
     fn set_sharding_key(&mut self, sharding_key: i64) -> Option<usize> {
         let sharder = Sharder::new(
             self.pool_settings.shards,
@@ -810,11 +841,22 @@ impl QueryRouter {
     /// Should we attempt to parse queries?
     pub fn query_parser_enabled(&self) -> bool {
         let enabled = match self.query_parser_enabled {
-            None => self.pool_settings.query_parser_enabled,
-            Some(value) => value,
-        };
+            None => {
+                debug!(
+                    "Using pool settings, query_parser_enabled: {}",
+                    self.pool_settings.query_parser_enabled
+                );
+                self.pool_settings.query_parser_enabled
+            }
 
-        debug!("Query parser enabled: {}", enabled);
+            Some(value) => {
+                debug!(
+                    "Using query parser override, query_parser_enabled: {}",
+                    value
+                );
+                value
+            }
+        };
 
         enabled
     }
@@ -862,7 +904,7 @@ mod test {
 
         for query in queries {
             // It's a recognized query
-            assert!(qr.infer(&query));
+            assert!(qr.infer(&QueryRouter::parse(&query).unwrap()).is_ok());
             assert_eq!(qr.role(), Some(Role::Replica));
         }
     }
@@ -881,7 +923,7 @@ mod test {
 
         for query in queries {
             // It's a recognized query
-            assert!(qr.infer(&query));
+            assert!(qr.infer(&QueryRouter::parse(&query).unwrap()).is_ok());
             assert_eq!(qr.role(), Some(Role::Primary));
         }
     }
@@ -893,7 +935,7 @@ mod test {
         let query = simple_query("SELECT * FROM items WHERE id = 5");
         assert!(qr.try_execute_command(&simple_query("SET PRIMARY READS TO on")) != None);
 
-        assert!(qr.infer(&query));
+        assert!(qr.infer(&QueryRouter::parse(&query).unwrap()).is_ok());
         assert_eq!(qr.role(), None);
     }
 
@@ -913,7 +955,7 @@ mod test {
         res.put(prepared_stmt);
         res.put_i16(0);
 
-        assert!(qr.infer(&res));
+        assert!(qr.infer(&QueryRouter::parse(&res).unwrap()).is_ok());
         assert_eq!(qr.role(), Some(Role::Replica));
     }
 
@@ -1077,11 +1119,11 @@ mod test {
         assert_eq!(qr.role(), None);
 
         let query = simple_query("INSERT INTO test_table VALUES (1)");
-        assert!(qr.infer(&query));
+        assert!(qr.infer(&QueryRouter::parse(&query).unwrap()).is_ok());
         assert_eq!(qr.role(), Some(Role::Primary));
 
         let query = simple_query("SELECT * FROM test_table");
-        assert!(qr.infer(&query));
+        assert!(qr.infer(&QueryRouter::parse(&query).unwrap()).is_ok());
         assert_eq!(qr.role(), Some(Role::Replica));
 
         assert!(qr.query_parser_enabled());
@@ -1113,6 +1155,8 @@ mod test {
             auth_query: None,
             auth_query_password: None,
             auth_query_user: None,
+            db: "test".to_string(),
+            plugins: None,
         };
         let mut qr = QueryRouter::new();
         assert_eq!(qr.active_role, None);
@@ -1142,15 +1186,24 @@ mod test {
         QueryRouter::setup();
 
         let mut qr = QueryRouter::new();
-        assert!(qr.infer(&simple_query("BEGIN; SELECT 1; COMMIT;")));
+        assert!(qr
+            .infer(&QueryRouter::parse(&simple_query("BEGIN; SELECT 1; COMMIT;")).unwrap())
+            .is_ok());
         assert_eq!(qr.role(), Role::Primary);
 
-        assert!(qr.infer(&simple_query("SELECT 1; SELECT 2;")));
+        assert!(qr
+            .infer(&QueryRouter::parse(&simple_query("SELECT 1; SELECT 2;")).unwrap())
+            .is_ok());
         assert_eq!(qr.role(), Role::Replica);
 
-        assert!(qr.infer(&simple_query(
-            "SELECT 123; INSERT INTO t VALUES (5); SELECT 1;"
-        )));
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query(
+                    "SELECT 123; INSERT INTO t VALUES (5); SELECT 1;"
+                ))
+                .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.role(), Role::Primary);
     }
 
@@ -1177,6 +1230,8 @@ mod test {
             auth_query: None,
             auth_query_password: None,
             auth_query_user: None,
+            db: "test".to_string(),
+            plugins: None,
         };
         let mut qr = QueryRouter::new();
         qr.update_pool_settings(pool_settings.clone());
@@ -1208,47 +1263,84 @@ mod test {
         qr.pool_settings.automatic_sharding_key = Some("data.id".to_string());
         qr.pool_settings.shards = 3;
 
-        assert!(qr.infer(&simple_query("SELECT * FROM data WHERE id = 5")));
+        assert!(qr
+            .infer(&QueryRouter::parse(&simple_query("SELECT * FROM data WHERE id = 5")).unwrap())
+            .is_ok());
         assert_eq!(qr.shard(), 2);
 
-        assert!(qr.infer(&simple_query(
-            "SELECT one, two, three FROM public.data WHERE id = 6"
-        )));
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query(
+                    "SELECT one, two, three FROM public.data WHERE id = 6"
+                ))
+                .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.shard(), 0);
 
-        assert!(qr.infer(&simple_query(
-            "SELECT * FROM data
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query(
+                    "SELECT * FROM data
             INNER JOIN t2 ON data.id = 5
             AND t2.data_id = data.id
         WHERE data.id = 5"
-        )));
+                ))
+                .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.shard(), 2);
 
         // Shard did not move because we couldn't determine the sharding key since it could be ambiguous
         // in the query.
-        assert!(qr.infer(&simple_query(
-            "SELECT * FROM t2 INNER JOIN data ON id = 6 AND data.id = t2.data_id"
-        )));
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query(
+                    "SELECT * FROM t2 INNER JOIN data ON id = 6 AND data.id = t2.data_id"
+                ))
+                .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.shard(), 2);
 
-        assert!(qr.infer(&simple_query(
-            r#"SELECT * FROM "public"."data" WHERE "id" = 6"#
-        )));
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query(
+                    r#"SELECT * FROM "public"."data" WHERE "id" = 6"#
+                ))
+                .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.shard(), 0);
 
-        assert!(qr.infer(&simple_query(
-            r#"SELECT * FROM "public"."data" WHERE "data"."id" = 5"#
-        )));
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query(
+                    r#"SELECT * FROM "public"."data" WHERE "data"."id" = 5"#
+                ))
+                .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.shard(), 2);
 
         // Super unique sharding key
         qr.pool_settings.automatic_sharding_key = Some("*.unique_enough_column_name".to_string());
-        assert!(qr.infer(&simple_query(
-            "SELECT * FROM table_x WHERE unique_enough_column_name = 6"
-        )));
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query(
+                    "SELECT * FROM table_x WHERE unique_enough_column_name = 6"
+                ))
+                .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.shard(), 0);
 
-        assert!(qr.infer(&simple_query("SELECT * FROM table_y WHERE another_key = 5")));
+        assert!(qr
+            .infer(
+                &QueryRouter::parse(&simple_query("SELECT * FROM table_y WHERE another_key = 5"))
+                    .unwrap()
+            )
+            .is_ok());
         assert_eq!(qr.shard(), 0);
     }
 
@@ -1272,11 +1364,36 @@ mod test {
         qr.pool_settings.automatic_sharding_key = Some("data.id".to_string());
         qr.pool_settings.shards = 3;
 
-        assert!(qr.infer(&simple_query(stmt)));
+        assert!(qr
+            .infer(&QueryRouter::parse(&simple_query(stmt)).unwrap())
+            .is_ok());
         assert_eq!(qr.placeholders.len(), 1);
 
         assert!(qr.infer_shard_from_bind(&bind));
         assert_eq!(qr.shard(), 2);
         assert!(qr.placeholders.is_empty());
     }
+
+    #[tokio::test]
+    async fn test_table_access_plugin() {
+        QueryRouter::setup();
+
+        let mut qr = QueryRouter::new();
+
+        let mut pool_settings = PoolSettings::default();
+        pool_settings.plugins = Some(vec![String::from("pg_table_access")]);
+        qr.update_pool_settings(pool_settings);
+
+        let query = simple_query("SELECT * FROM pg_database");
+        let ast = QueryRouter::parse(&query).unwrap();
+
+        let res = qr.execute_plugins(&ast).await;
+
+        assert_eq!(
+            res,
+            Ok(PluginOutput::Deny(
+                "permission for table \"pg_database\" denied".to_string()
+            ))
+        );
+    }
 }