/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.hbase.security.visibility;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.security.visibility.expression.ExpressionNode;
import org.apache.hadoop.hbase.security.visibility.expression.LeafExpressionNode;
import org.apache.hadoop.hbase.security.visibility.expression.NonLeafExpressionNode;
import org.apache.hadoop.hbase.security.visibility.expression.Operator;
import org.apache.hadoop.hbase.util.Bytes;
@InterfaceAudience.Private
public class ExpressionParser {
private static final char CLOSE_PARAN = ')';
private static final char OPEN_PARAN = '(';
private static final char OR = '|';
private static final char AND = '&';
private static final char NOT = '!';
private static final char SPACE = ' ';
private static final char DOUBLE_QUOTES = '"';
public ExpressionNode parse(String expS) throws ParseException {
expS = expS.trim();
Stack<ExpressionNode> expStack = new Stack<ExpressionNode>();
int index = 0;
byte[] exp = Bytes.toBytes(expS);
int endPos = exp.length;
while (index < endPos) {
byte b = exp[index];
switch (b) {
case OPEN_PARAN:
processOpenParan(expStack, expS, index);
index = skipSpaces(exp, index);
break;
case CLOSE_PARAN:
processCloseParan(expStack, expS, index);
index = skipSpaces(exp, index);
break;
case AND:
case OR:
processANDorOROp(getOperator(b), expStack, expS, index);
index = skipSpaces(exp, index);
break;
case NOT:
processNOTOp(expStack, expS, index);
break;
case DOUBLE_QUOTES:
int labelOffset = ++index;
// We have to rewrite the expression within double quotes as incase of expressions
// with escape characters we may have to avoid them as the original expression did
// not have them
List<Byte> list = new ArrayList<Byte>();
while (index < endPos && !endDoubleQuotesFound(exp[index])) {
if (exp[index] == '\\') {
index++;
if (exp[index] != '\\' && exp[index] != '"')
throw new ParseException("invalid escaping with quotes " + expS + " at column : "
+ index);
}
list.add(exp[index]);
index++;
}
// The expression has come to the end. still no double quotes found
if(index == endPos) {
throw new ParseException("No terminating quotes " + expS + " at column : " + index);
}
// This could be costly. but do we have any alternative?
// If we don't do this way then we may have to handle while checking the authorizations.
// Better to do it here.
byte[] array = com.google.common.primitives.Bytes.toArray(list);
String leafExp = Bytes.toString(array).trim();
if (leafExp.isEmpty()) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
processLabelExpNode(new LeafExpressionNode(leafExp), expStack, expS, index);
index = skipSpaces(exp, index);
break;
default:
labelOffset = index;
do {
if (!VisibilityLabelsValidator.isValidAuthChar(exp[index])) {
throw new ParseException("Error parsing expression "
+ expS + " at column : " + index);
}
index++;
} while (index < endPos && !isEndOfLabel(exp[index]));
leafExp = new String(exp, labelOffset, index - labelOffset).trim();
if (leafExp.isEmpty()) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
processLabelExpNode(new LeafExpressionNode(leafExp), expStack, expS, index);
// We already crossed the label node index. So need to reduce 1 here.
index--;
index = skipSpaces(exp, index);
}
index++;
}
if (expStack.size() != 1) {
throw new ParseException("Error parsing expression " + expS);
}
ExpressionNode top = expStack.pop();
if (top == LeafExpressionNode.OPEN_PARAN_NODE) {
throw new ParseException("Error parsing expression " + expS);
}
if (top instanceof NonLeafExpressionNode) {
NonLeafExpressionNode nlTop = (NonLeafExpressionNode) top;
if (nlTop.getOperator() == Operator.NOT) {
if (nlTop.getChildExps().size() != 1) {
throw new ParseException("Error parsing expression " + expS);
}
} else if (nlTop.getChildExps().size() != 2) {
throw new ParseException("Error parsing expression " + expS);
}
}
return top;
}
private int skipSpaces(byte[] exp, int index) {
while (index < exp.length -1 && exp[index+1] == SPACE) {
index++;
}
return index;
}
private void processCloseParan(Stack<ExpressionNode> expStack, String expS, int index)
throws ParseException {
if (expStack.size() < 2) {
// When ) comes we expect atleast a ( node and another leaf/non leaf node
// in stack.
throw new ParseException();
} else {
ExpressionNode top = expStack.pop();
ExpressionNode secondTop = expStack.pop();
// The second top must be a ( node and top should not be a ). Top can be
// any thing else
if (top == LeafExpressionNode.OPEN_PARAN_NODE
|| secondTop != LeafExpressionNode.OPEN_PARAN_NODE) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
// a&(b|) is not valid.
// The top can be a ! node but with exactly child nodes. !).. is invalid
// Other NonLeafExpressionNode , then there should be exactly 2 child.
// (a&) is not valid.
if (top instanceof NonLeafExpressionNode) {
NonLeafExpressionNode nlTop = (NonLeafExpressionNode) top;
if ((nlTop.getOperator() == Operator.NOT && nlTop.getChildExps().size() != 1)
|| (nlTop.getOperator() != Operator.NOT && nlTop.getChildExps().size() != 2)) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
}
// When (a|b)&(c|d) comes while processing the second ) there will be
// already (a|b)& node
// avail in the stack. The top will be c|d node. We need to take it out
// and combine as one
// node.
if (!expStack.isEmpty()) {
ExpressionNode thirdTop = expStack.peek();
if (thirdTop instanceof NonLeafExpressionNode) {
NonLeafExpressionNode nlThirdTop = (NonLeafExpressionNode) expStack.pop();
nlThirdTop.addChildExp(top);
if (nlThirdTop.getOperator() == Operator.NOT) {
// It is a NOT node. So there may be a NonLeafExpressionNode below
// it to which the
// completed NOT can be added now.
if (!expStack.isEmpty()) {
ExpressionNode fourthTop = expStack.peek();
if (fourthTop instanceof NonLeafExpressionNode) {
// Its Operator will be OR or AND
NonLeafExpressionNode nlFourthTop = (NonLeafExpressionNode) fourthTop;
assert nlFourthTop.getOperator() != Operator.NOT;
// Also for sure its number of children will be 1
assert nlFourthTop.getChildExps().size() == 1;
nlFourthTop.addChildExp(nlThirdTop);
return;// This case no need to add back the nlThirdTop.
}
}
}
top = nlThirdTop;
}
}
expStack.push(top);
}
}
private void processOpenParan(Stack<ExpressionNode> expStack, String expS, int index)
throws ParseException {
if (!expStack.isEmpty()) {
ExpressionNode top = expStack.peek();
// Top can not be a Label Node. a(.. is not valid. but ((a.. is fine.
if (top instanceof LeafExpressionNode && top != LeafExpressionNode.OPEN_PARAN_NODE) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
} else if (top instanceof NonLeafExpressionNode) {
// Top is non leaf.
// It can be ! node but with out any child nodes. !a(.. is invalid
// Other NonLeafExpressionNode , then there should be exactly 1 child.
// a&b( is not valid.
// a&( is valid though. Also !( is valid
NonLeafExpressionNode nlTop = (NonLeafExpressionNode) top;
if ((nlTop.getOperator() == Operator.NOT && nlTop.getChildExps().size() != 0)
|| (nlTop.getOperator() != Operator.NOT && nlTop.getChildExps().size() != 1)) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
}
}
expStack.push(LeafExpressionNode.OPEN_PARAN_NODE);
}
private void processLabelExpNode(LeafExpressionNode node, Stack<ExpressionNode> expStack,
String expS, int index) throws ParseException {
if (expStack.isEmpty()) {
expStack.push(node);
} else {
ExpressionNode top = expStack.peek();
if (top == LeafExpressionNode.OPEN_PARAN_NODE) {
expStack.push(node);
} else if (top instanceof NonLeafExpressionNode) {
NonLeafExpressionNode nlTop = (NonLeafExpressionNode) expStack.pop();
nlTop.addChildExp(node);
if (nlTop.getOperator() == Operator.NOT && !expStack.isEmpty()) {
ExpressionNode secondTop = expStack.peek();
if (secondTop == LeafExpressionNode.OPEN_PARAN_NODE) {
expStack.push(nlTop);
} else if (secondTop instanceof NonLeafExpressionNode) {
((NonLeafExpressionNode) secondTop).addChildExp(nlTop);
}
} else {
expStack.push(nlTop);
}
} else {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
}
}
private void processANDorOROp(Operator op, Stack<ExpressionNode> expStack, String expS, int index)
throws ParseException {
if (expStack.isEmpty()) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
ExpressionNode top = expStack.pop();
if (top.isSingleNode()) {
if (top == LeafExpressionNode.OPEN_PARAN_NODE) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
expStack.push(new NonLeafExpressionNode(op, top));
} else {
NonLeafExpressionNode nlTop = (NonLeafExpressionNode) top;
if (nlTop.getChildExps().size() != 2) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
expStack.push(new NonLeafExpressionNode(op, nlTop));
}
}
private void processNOTOp(Stack<ExpressionNode> expStack, String expS, int index)
throws ParseException {
// When ! comes, the stack can be empty or top ( or top can be some exp like
// a&
// !!.., a!, a&b!, !a! are invalid
if (!expStack.isEmpty()) {
ExpressionNode top = expStack.peek();
if (top.isSingleNode() && top != LeafExpressionNode.OPEN_PARAN_NODE) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
if (!top.isSingleNode() && ((NonLeafExpressionNode) top).getChildExps().size() != 1) {
throw new ParseException("Error parsing expression " + expS + " at column : " + index);
}
}
expStack.push(new NonLeafExpressionNode(Operator.NOT));
}
private static boolean endDoubleQuotesFound(byte b) {
return (b == DOUBLE_QUOTES);
}
private static boolean isEndOfLabel(byte b) {
return (b == OPEN_PARAN || b == CLOSE_PARAN || b == OR || b == AND ||
b == NOT || b == SPACE);
}
private static Operator getOperator(byte op) {
switch (op) {
case AND:
return Operator.AND;
case OR:
return Operator.OR;
case NOT:
return Operator.NOT;
}
return null;
}
}