improve WallFilter

src/main/java/com/alibaba/druid/wall/WallConfig.java

@@ -51,6 +51,8 @@ public class WallConfig implements WallConfigMBean {
 
     private boolean             commentAllow               = false;
 
+    private boolean             describeAllow              = false;
+
     private boolean             schemaCheck                = true;
     private boolean             tableCheck                 = true;
     private boolean             functionCheck              = true;
@@ -173,6 +175,24 @@ public class WallConfig implements WallConfigMBean {
         this.noneBaseStatementAllow = noneBaseStatementAllow;
     }
 
+    /**
+     * allow mysql describe statement
+     * @since 0.2.10
+     * @return
+     */
+    public boolean isDescribeAllow() {
+        return describeAllow;
+    }
+
+    /**
+     * set allow mysql describe statement
+     * @since 0.2.10
+     * @return
+     */
+    public void setDescribeAllow(boolean describeAllow) {
+        this.describeAllow = describeAllow;
+    }
+
     public boolean isTruncateAllow() {
         return truncateAllow;
     }

src/main/java/com/alibaba/druid/wall/spi/MySqlWallVisitor.java

@@ -41,6 +41,7 @@ import com.alibaba.druid.sql.ast.statement.SQLUnionQuery;
 import com.alibaba.druid.sql.ast.statement.SQLUpdateStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.expr.MySqlOutFileExpr;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlDeleteStatement;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlDescribeStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlInsertStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectGroupBy;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
@@ -259,6 +260,8 @@ public class MySqlWallVisitor extends MySqlASTVisitorAdapter implements WallVisi
             allow = true;
         } else if (x instanceof SQLTruncateStatement) {
             allow = config.isTruncateAllow();
+        } else if (x instanceof MySqlDescribeStatement) {
+            allow = config.isDescribeAllow();
         }
 
         if (!allow) {