content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.alibaba.druid.wall;
  
  import com.alibaba.druid.DbType;
  import com.alibaba.druid.sql.PagerUtils;
  import com.alibaba.druid.sql.SQLUtils;
  import com.alibaba.druid.sql.ast.*;
  import com.alibaba.druid.sql.ast.expr.*;
  import com.alibaba.druid.sql.ast.statement.*;
  import com.alibaba.druid.sql.visitor.SQLASTVisitor;
  import com.alibaba.druid.wall.spi.WallVisitorUtils;
  import com.alibaba.druid.wall.violation.ErrorCode;
  import com.alibaba.druid.wall.violation.IllegalSQLObjectViolation;
  
  import java.util.List;
  
  public interface WallVisitor extends SQLASTVisitor {
      WallConfig getConfig();
  
      WallProvider getProvider();
  
      List<Violation> getViolations();
  
      void addViolation(Violation violation);
  
      boolean isDenyTable(String name);
  
      default String toSQL(SQLObject obj) {
          return SQLUtils.toSQLString(obj, getDbType());
      }
  
      boolean isSqlModified();
  
      void setSqlModified(boolean sqlModified);
  
      DbType getDbType();
  
      boolean isSqlEndOfComment();
  
      void setSqlEndOfComment(boolean sqlEndOfComment);
  
      void addWallUpdateCheckItem(WallUpdateCheckItem item);
  
      List<WallUpdateCheckItem> getUpdateCheckItems();
  
      default boolean visit(SQLPropertyExpr x) {
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLInListExpr x) {
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLBinaryOpExpr x) {
          return WallVisitorUtils.check(this, x);
      }
  
      default boolean visit(SQLMethodInvokeExpr x) {
          WallVisitorUtils.checkFunction(this, x);
          return true;
      }
  
      default boolean visit(SQLSelectQueryBlock x) {
          WallVisitorUtils.checkSelect(this, x);
  
          return true;
      }
  
      default boolean visit(SQLSelectGroupByClause x) {
          WallVisitorUtils.checkHaving(this, x.getHaving());
          return true;
      }
  
      @Override
      default boolean visit(SQLSelectItem x) {
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLJoinTableSource x) {
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLCreateTableStatement x) {
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLAlterTableStatement x) {
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLDropTableStatement x) {
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLUpdateStatement x) {
          WallVisitorUtils.initWallTopStatementContext();
          WallVisitorUtils.checkUpdate(this, x);
  
          return true;
      }
  
      default void endVisit(SQLUpdateStatement x) {
          WallVisitorUtils.clearWallTopStatementContext();
      }
  
      default boolean visit(SQLInsertStatement x) {
          WallVisitorUtils.initWallTopStatementContext();
          WallVisitorUtils.checkInsert(this, x);
  
          return true;
      }
  
      default void endVisit(SQLInsertStatement x) {
          WallVisitorUtils.clearWallTopStatementContext();
      }
  
      default boolean visit(SQLDeleteStatement x) {
          WallVisitorUtils.checkDelete(this, x);
          return true;
      }
  
      default void preVisit(SQLObject x) {
          WallVisitorUtils.preVisitCheck(this, x);
      }
  
      @Override
      default boolean visit(SQLSelectStatement x) {
          WallConfig config = getConfig();
          if (!config.isSelectAllow()) {
              this.getViolations()
                      .add(new IllegalSQLObjectViolation(ErrorCode.SELECT_NOT_ALLOW, "select not allow",
                              this.toSQL(x)));
              return false;
          }
  
          WallVisitorUtils.initWallTopStatementContext();
  
          int selectLimit = config.getSelectLimit();
          if (selectLimit >= 0) {
              SQLSelect select = x.getSelect();
              PagerUtils.limit(select, getDbType(), 0, selectLimit, true);
              setSqlModified(true);
          }
          return true;
      }
  
      default void endVisit(SQLSelectStatement x) {
          WallVisitorUtils.clearWallTopStatementContext();
      }
  
      default boolean visit(SQLExprTableSource x) {
          WallVisitorUtils.check(this, x);
  
          if (x.getExpr() instanceof SQLName) {
              return false;
          }
  
          return true;
      }
  
      default boolean visit(SQLIdentifierExpr x) {
          WallConfig config = getConfig();
          String name = x.getName();
          name = WallVisitorUtils.form(name);
          if (config.isVariantCheck() && config.getDenyVariants().contains(name)) {
              getViolations().add(new IllegalSQLObjectViolation(ErrorCode.VARIANT_DENY, "variable not allow : " + name,
                      toSQL(x)));
          }
          return true;
      }
  
      default boolean visit(SQLUnionQuery x) {
          return WallVisitorUtils.checkUnion(this, x);
      }
  
      default void endVisit(SQLDeleteStatement x) {
          WallVisitorUtils.clearWallTopStatementContext();
      }
  
      default boolean visit(SQLLimit x) {
          if (x.getRowCount() instanceof SQLNumericLiteralExpr) {
              WallContext context = WallContext.current();
  
              int rowCount = ((SQLNumericLiteralExpr) x.getRowCount()).getNumber().intValue();
              if (rowCount == 0) {
                  if (context != null) {
                      context.incrementWarnings();
                  }
  
                  if (!getProvider().getConfig().isLimitZeroAllow()) {
                      this.getViolations().add(new IllegalSQLObjectViolation(ErrorCode.LIMIT_ZERO, "limit row 0",
                              this.toSQL(x)));
                  }
              }
          }
          return true;
      }
  
      default boolean visit(SQLCreateTriggerStatement x) {
          return false;
      }
  
      default boolean visit(SQLSetStatement x) {
          return false;
      }
  
      default boolean visit(SQLCallStatement x) {
          return false;
      }
  
      default boolean visit(SQLCommentHint x) {
          if (x instanceof TDDLHint) {
              return false;
          }
          WallVisitorUtils.check(this, x);
          return true;
      }
  
      default boolean visit(SQLShowCreateTableStatement x) {
          String tableName = (x.getName()).getSimpleName();
          WallContext context = WallContext.current();
          if (context != null) {
              WallSqlTableStat tableStat = context.getTableStat(tableName);
              if (tableStat != null) {
                  tableStat.incrementShowCount();
              }
          }
          return false;
      }
  }
  