fix: nil guards, safe type assertions, panic prevention, and rate limiter plugin (#3757)

Signed-off-by: Srikanth Patchava <spatchava@meta.com>
Signed-off-by: Srikanth Patchava <srpatcha@users.noreply.github.com>
Co-authored-by: Srikanth Patchava <srpatcha@users.noreply.github.com>

plugins/golang-filter/mcp-server/servers/gorm/db.go

@@ -164,14 +164,14 @@ func (c *DBClient) DescribeTable(table string) ([]map[string]interface{}, error)
 	switch c.dbType {
 	case MYSQL:
 		sql = `
-			select 
+			select
 			    column_name,
 				column_type,
 				is_nullable,
 				column_key,
 				column_default,
 				extra,
-				column_comment 
+				column_comment
 			from information_schema.columns
 			where table_schema = database() and table_name = ?
 		`
@@ -179,17 +179,17 @@ func (c *DBClient) DescribeTable(table string) ([]map[string]interface{}, error)
 
 	case POSTGRES:
 		sql = `
-			select 
+			select
 			    column_name,
 				data_type as column_type,
 				is_nullable,
-				case 
+				case
 				    when column_default like 'nextval%' then 'auto_increment'
 				    when column_default is not null then 'default'
 				    else ''
 				end as column_key,
 				column_default,
-				case 
+				case
 				    when column_default like 'nextval%' then 'auto_increment'
 				    else ''
 				end as extra,
@@ -202,7 +202,7 @@ func (c *DBClient) DescribeTable(table string) ([]map[string]interface{}, error)
 
 	case CLICKHOUSE:
 		sql = `
-			select 
+			select
 			    name as column_name,
 				type as column_type,
 				if(is_nullable, 'YES', 'NO') as is_nullable,
@@ -217,7 +217,7 @@ func (c *DBClient) DescribeTable(table string) ([]map[string]interface{}, error)
 
 	case SQLITE:
 		sql = `
-			select 
+			select
 			    name as column_name,
 				type as column_type,
 				not (notnull = 1) as is_nullable,
@@ -236,6 +236,10 @@ func (c *DBClient) DescribeTable(table string) ([]map[string]interface{}, error)
 
 // ListTables List all tables in the connected database.
 func (c *DBClient) ListTables() ([]string, error) {
+	if err := c.reconnectIfDbEmpty(); err != nil {
+		return nil, err
+	}
+
 	var sql string
 	switch c.dbType {
 	case MYSQL:
@@ -265,6 +269,10 @@ func (c *DBClient) ListTables() ([]string, error) {
 		tables = append(tables, table)
 	}
 
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("error iterating table rows: %w", err)
+	}
+
 	return tables, nil
 }
 
@@ -335,6 +343,10 @@ func (c *DBClient) Query(sql string, args ...interface{}) ([]map[string]interfac
 		results = append(results, rowMap)
 	}
 
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("failed to iterate table rows in Query: %w", err)
+	}
+
 	return results, nil
 }
 

plugins/golang-filter/mcp-server/servers/rag/vectordb/milvus.go

@@ -792,22 +792,36 @@ func (m *MilvusProvider) ListDocs(ctx context.Context, limit int) ([]schema.Docu
 			fieldName := strings.ToLower(fieldMapping.StandardName)
 			switch fieldName {
 			case "id":
-				if v, err := col.(*entity.ColumnVarChar).Get(i); err == nil {
-					id = v.(string)
+				if typedCol, ok := col.(*entity.ColumnVarChar); ok {
+					if v, err := typedCol.Get(i); err == nil {
+						if s, ok := v.(string); ok {
+							id = s
+						}
+					}
 				}
 			case "content":
-				if v, err := col.(*entity.ColumnVarChar).Get(i); err == nil {
-					content = v.(string)
+				if typedCol, ok := col.(*entity.ColumnVarChar); ok {
+					if v, err := typedCol.Get(i); err == nil {
+						if s, ok := v.(string); ok {
+							content = s
+						}
+					}
 				}
 			case "metadata":
-				if v, err := col.(*entity.ColumnJSONBytes).Get(i); err == nil {
-					if bytes, ok := v.([]byte); ok {
-						_ = json.Unmarshal(bytes, &metadata)
+				if typedCol, ok := col.(*entity.ColumnJSONBytes); ok {
+					if v, err := typedCol.Get(i); err == nil {
+						if bytes, ok := v.([]byte); ok {
+							_ = json.Unmarshal(bytes, &metadata)
+						}
 					}
 				}
 			case "created_at":
-				if v, err := col.(*entity.ColumnInt64).Get(i); err == nil {
-					createdAt = v.(int64)
+				if typedCol, ok := col.(*entity.ColumnInt64); ok {
+					if v, err := typedCol.Get(i); err == nil {
+						if ts, ok := v.(int64); ok {
+							createdAt = ts
+						}
+					}
 				}
 			}
 		}

plugins/wasm-go/extensions/request-block/main.go

@@ -87,13 +87,17 @@ func parseConfig(json gjson.Result, config *RequestBlockConfig, log log.Log) err
 		if regexpUrl == "" {
 			continue
 		}
+		var reg *regexp.Regexp
+		var err error
 		if config.caseSensitive {
-			reg := regexp.MustCompile(regexpUrl)
-			config.blockRegExpArray = append(config.blockRegExpArray, reg)
+			reg, err = regexp.Compile(regexpUrl)
 		} else {
-			reg := regexp.MustCompile(strings.ToLower(regexpUrl))
-			config.blockRegExpArray = append(config.blockRegExpArray, reg)
+			reg, err = regexp.Compile(strings.ToLower(regexpUrl))
 		}
+		if err != nil {
+			return fmt.Errorf("invalid regexp pattern %q: %w", regexpUrl, err)
+		}
+		config.blockRegExpArray = append(config.blockRegExpArray, reg)
 	}
 	for _, item := range json.Get("block_headers").Array() {
 		header := item.String()