io.undertow.util.HeaderTokenParser Maven / Gradle / Ivy
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* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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 io.undertow.util;
import static io.undertow.UndertowMessages.MESSAGES;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* Utility to parse the tokens contained within a HTTP header.
*
* @author Darran Lofthouse
*/
public class HeaderTokenParser {
private static final char EQUALS = '=';
private static final char COMMA = ',';
private static final char QUOTE = '"';
private static final char ESCAPE = '\\';
private final Map expectedTokens;
public HeaderTokenParser(final Map expectedTokens) {
this.expectedTokens = expectedTokens;
}
public Map parseHeader(final String header) {
char[] headerChars = header.toCharArray();
// The LinkedHashMap is used so that the parameter order can also be retained.
Map response = new LinkedHashMap<>();
SearchingFor searchingFor = SearchingFor.START_OF_NAME;
int nameStart = 0;
E currentToken = null;
int valueStart = 0;
int escapeCount = 0;
boolean containsEscapes = false;
for (int i = 0; i < headerChars.length; i++) {
switch (searchingFor) {
case START_OF_NAME:
// Eliminate any white space before the name of the parameter.
if (headerChars[i] != COMMA && !Character.isWhitespace(headerChars[i])) {
nameStart = i;
searchingFor = SearchingFor.EQUALS_SIGN;
}
break;
case EQUALS_SIGN:
if (headerChars[i] == EQUALS) {
String paramName = String.valueOf(headerChars, nameStart, i - nameStart);
currentToken = expectedTokens.get(paramName);
if (currentToken == null) {
throw MESSAGES.unexpectedTokenInHeader(paramName);
}
searchingFor = SearchingFor.START_OF_VALUE;
}
break;
case START_OF_VALUE:
if (!Character.isWhitespace(headerChars[i])) {
if (headerChars[i] == QUOTE && currentToken.isAllowQuoted()) {
valueStart = i + 1;
searchingFor = SearchingFor.LAST_QUOTE;
} else {
valueStart = i;
searchingFor = SearchingFor.END_OF_VALUE;
}
}
break;
case LAST_QUOTE:
if (headerChars[i] == ESCAPE) {
escapeCount++;
containsEscapes = true;
} else if (headerChars[i] == QUOTE && (escapeCount % 2 == 0)) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
if(containsEscapes) {
StringBuilder sb = new StringBuilder();
boolean lastEscape = false;
for(int j = 0; j < value.length(); ++j) {
char c = value.charAt(j);
if(c == ESCAPE && !lastEscape) {
lastEscape = true;
} else {
lastEscape = false;
sb.append(c);
}
}
value = sb.toString();
containsEscapes = false;
}
response.put(currentToken, value);
searchingFor = SearchingFor.START_OF_NAME;
escapeCount = 0;
} else {
escapeCount = 0;
}
break;
case END_OF_VALUE:
if (headerChars[i] == COMMA || Character.isWhitespace(headerChars[i])) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
response.put(currentToken, value);
searchingFor = SearchingFor.START_OF_NAME;
}
break;
}
}
if (searchingFor == SearchingFor.END_OF_VALUE) {
// Special case where we reached the end of the array containing the header values.
String value = String.valueOf(headerChars, valueStart, headerChars.length - valueStart);
response.put(currentToken, value);
} else if (searchingFor != SearchingFor.START_OF_NAME) {
// Somehow we are still in the middle of searching for a current value.
throw MESSAGES.invalidHeader();
}
return response;
}
enum SearchingFor {
START_OF_NAME, EQUALS_SIGN, START_OF_VALUE, LAST_QUOTE, END_OF_VALUE;
}
}