org.apache.tomcat.util.http.parser.HttpParser Maven / Gradle / Ivy
/*
* 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.tomcat.util.http.parser;
import java.io.IOException;
import java.io.StringReader;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Locale;
import java.util.Map;
/**
* HTTP header value parser implementation. Parsing HTTP headers as per RFC2616
* is not always as simple as it first appears. For headers that only use tokens
* the simple approach will normally be sufficient. However, for the other
* headers, while simple code meets 99.9% of cases, there are often some edge
* cases that make things far more complicated.
*
* The purpose of this parser is to let the parser worry about the edge cases.
* It provides tolerant (where safe to do so) parsing of HTTP header values
* assuming that wrapped header lines have already been unwrapped. (The Tomcat
* header processing code does the unwrapping.)
*
* Provides parsing of the following HTTP header values as per RFC 2616:
* - Authorization for DIGEST authentication
* - MediaType (used for Content-Type header)
*
* Support for additional headers will be provided as required.
*/
public class HttpParser {
@SuppressWarnings("unused") // Unused due to buggy client implementations
private static final Integer FIELD_TYPE_TOKEN = Integer.valueOf(0);
private static final Integer FIELD_TYPE_QUOTED_STRING = Integer.valueOf(1);
private static final Integer FIELD_TYPE_TOKEN_OR_QUOTED_STRING = Integer.valueOf(2);
private static final Integer FIELD_TYPE_LHEX = Integer.valueOf(3);
private static final Integer FIELD_TYPE_QUOTED_TOKEN = Integer.valueOf(4);
private static final Map fieldTypes = new HashMap<>();
// Arrays used by isToken(), isHex()
private static final boolean isToken[] = new boolean[128];
private static final boolean isHex[] = new boolean[128];
static {
// Digest field types.
// Note: These are more relaxed than RFC2617. This adheres to the
// recommendation of RFC2616 that servers are tolerant of buggy
// clients when they can be so without ambiguity.
fieldTypes.put("username", FIELD_TYPE_QUOTED_STRING);
fieldTypes.put("realm", FIELD_TYPE_QUOTED_STRING);
fieldTypes.put("nonce", FIELD_TYPE_QUOTED_STRING);
fieldTypes.put("digest-uri", FIELD_TYPE_QUOTED_STRING);
// RFC2617 says response is <">32LHEX<">. 32LHEX will also be accepted
fieldTypes.put("response", FIELD_TYPE_LHEX);
// RFC2617 says algorithm is token. <">token<"> will also be accepted
fieldTypes.put("algorithm", FIELD_TYPE_QUOTED_TOKEN);
fieldTypes.put("cnonce", FIELD_TYPE_QUOTED_STRING);
fieldTypes.put("opaque", FIELD_TYPE_QUOTED_STRING);
// RFC2617 says qop is token. <">token<"> will also be accepted
fieldTypes.put("qop", FIELD_TYPE_QUOTED_TOKEN);
// RFC2617 says nc is 8LHEX. <">8LHEX<"> will also be accepted
fieldTypes.put("nc", FIELD_TYPE_LHEX);
// Setup the flag arrays
for (int i = 0; i < 128; i++) {
if (i < 32) {
isToken[i] = false;
} else if (i == '(' || i == ')' || i == '<' || i == '>' || i == '@' ||
i == ',' || i == ';' || i == ':' || i == '\\' || i == '\"' ||
i == '/' || i == '[' || i == ']' || i == '?' || i == '=' ||
i == '{' || i == '}' || i == ' ' || i == '\t') {
isToken[i] = false;
} else {
isToken[i] = true;
}
if (i >= '0' && i <= '9' || i >= 'A' && i <= 'F' ||
i >= 'a' && i <= 'f') {
isHex[i] = true;
} else {
isHex[i] = false;
}
}
}
/**
* Parses an HTTP Authorization header for DIGEST authentication as per RFC
* 2617 section 3.2.2.
*
* @param input The header value to parse
*
* @return A map of directives and values as {@link String}s or
* null if a parsing error occurs. Although the
* values returned are {@link String}s they will have been
* validated to ensure that they conform to RFC 2617.
*
* @throws IllegalArgumentException If the header does not conform to RFC
* 2617
* @throws IOException If an error occurs while reading the input
*/
public static Map parseAuthorizationDigest (
StringReader input) throws IllegalArgumentException, IOException {
Map result = new HashMap<>();
if (skipConstant(input, "Digest") != SkipConstantResult.FOUND) {
return null;
}
// All field names are valid tokens
String field = readToken(input);
if (field == null) {
return null;
}
while (!field.equals("")) {
if (skipConstant(input, "=") != SkipConstantResult.FOUND) {
return null;
}
String value = null;
Integer type = fieldTypes.get(field.toLowerCase(Locale.ENGLISH));
if (type == null) {
// auth-param = token "=" ( token | quoted-string )
type = FIELD_TYPE_TOKEN_OR_QUOTED_STRING;
}
switch (type.intValue()) {
case 0:
// FIELD_TYPE_TOKEN
value = readToken(input);
break;
case 1:
// FIELD_TYPE_QUOTED_STRING
value = readQuotedString(input, false);
break;
case 2:
// FIELD_TYPE_TOKEN_OR_QUOTED_STRING
value = readTokenOrQuotedString(input, false);
break;
case 3:
// FIELD_TYPE_LHEX
value = readLhex(input);
break;
case 4:
// FIELD_TYPE_QUOTED_TOKEN
value = readQuotedToken(input);
break;
default:
// Error
throw new IllegalArgumentException(
"TODO i18n: Unsupported type");
}
if (value == null) {
return null;
}
result.put(field, value);
if (skipConstant(input, ",") == SkipConstantResult.NOT_FOUND) {
return null;
}
field = readToken(input);
if (field == null) {
return null;
}
}
return result;
}
public static MediaType parseMediaType(StringReader input)
throws IOException {
// Type (required)
String type = readToken(input);
if (type == null || type.length() == 0) {
return null;
}
if (skipConstant(input, "/") == SkipConstantResult.NOT_FOUND) {
return null;
}
// Subtype (required)
String subtype = readToken(input);
if (subtype == null || subtype.length() == 0) {
return null;
}
LinkedHashMap parameters = new LinkedHashMap<>();
SkipConstantResult lookForSemiColon = skipConstant(input, ";");
if (lookForSemiColon == SkipConstantResult.NOT_FOUND) {
return null;
}
while (lookForSemiColon == SkipConstantResult.FOUND) {
String attribute = readToken(input);
String value = "";
if (skipConstant(input, "=") == SkipConstantResult.FOUND) {
value = readTokenOrQuotedString(input, true);
}
if (attribute != null) {
parameters.put(attribute.toLowerCase(Locale.ENGLISH), value);
}
lookForSemiColon = skipConstant(input, ";");
if (lookForSemiColon == SkipConstantResult.NOT_FOUND) {
return null;
}
}
return new MediaType(type, subtype, parameters);
}
public static String unquote(String input) {
if (input == null || input.length() < 2 || input.charAt(0) != '"') {
return input;
}
StringBuilder result = new StringBuilder();
for (int i = 1 ; i < (input.length() - 1); i++) {
char c = input.charAt(i);
if (input.charAt(i) == '\\') {
i++;
result.append(input.charAt(i));
} else {
result.append(c);
}
}
return result.toString();
}
private static boolean isToken(int c) {
// Fast for correct values, slower for incorrect ones
try {
return isToken[c];
} catch (ArrayIndexOutOfBoundsException ex) {
return false;
}
}
private static boolean isHex(int c) {
// Fast for correct values, slower for incorrect ones
try {
return isHex[c];
} catch (ArrayIndexOutOfBoundsException ex) {
return false;
}
}
// Skip any LWS and return the next char
private static int skipLws(StringReader input, boolean withReset)
throws IOException {
if (withReset) {
input.mark(1);
}
int c = input.read();
while (c == 32 || c == 9 || c == 10 || c == 13) {
if (withReset) {
input.mark(1);
}
c = input.read();
}
if (withReset) {
input.reset();
}
return c;
}
private static SkipConstantResult skipConstant(StringReader input,
String constant) throws IOException {
int len = constant.length();
int c = skipLws(input, false);
for (int i = 0; i < len; i++) {
if (i == 0 && c == -1) {
return SkipConstantResult.EOF;
}
if (c != constant.charAt(i)) {
input.skip(-(i + 1));
return SkipConstantResult.NOT_FOUND;
}
if (i != (len - 1)) {
c = input.read();
}
}
return SkipConstantResult.FOUND;
}
/**
* @return the token if one was found, the empty string if no data was
* available to read or null if data other than a
* token was found
*/
private static String readToken(StringReader input) throws IOException {
StringBuilder result = new StringBuilder();
int c = skipLws(input, false);
while (c != -1 && isToken(c)) {
result.append((char) c);
c = input.read();
}
// Skip back so non-token character is available for next read
input.skip(-1);
if (c != -1 && result.length() == 0) {
return null;
} else {
return result.toString();
}
}
/**
* @return the quoted string if one was found, null if data other than a
* quoted string was found or null if the end of data was reached
* before the quoted string was terminated
*/
private static String readQuotedString(StringReader input,
boolean returnQuoted) throws IOException {
int c = skipLws(input, false);
if (c != '"') {
return null;
}
StringBuilder result = new StringBuilder();
if (returnQuoted) {
result.append('\"');
}
c = input.read();
while (c != '"') {
if (c == -1) {
return null;
} else if (c == '\\') {
c = input.read();
if (returnQuoted) {
result.append('\\');
}
result.append(c);
} else {
result.append((char) c);
}
c = input.read();
}
if (returnQuoted) {
result.append('\"');
}
return result.toString();
}
private static String readTokenOrQuotedString(StringReader input,
boolean returnQuoted) throws IOException {
// Go back so first non-LWS character is available to be read again
int c = skipLws(input, true);
if (c == '"') {
return readQuotedString(input, returnQuoted);
} else {
return readToken(input);
}
}
/**
* Token can be read unambiguously with or without surrounding quotes so
* this parsing method for token permits optional surrounding double quotes.
* This is not defined in any RFC. It is a special case to handle data from
* buggy clients (known buggy clients for DIGEST auth include Microsoft IE 8
* & 9, Apple Safari for OSX and iOS) that add quotes to values that
* should be tokens.
*
* @return the token if one was found, null if data other than a token or
* quoted token was found or null if the end of data was reached
* before a quoted token was terminated
*/
private static String readQuotedToken(StringReader input)
throws IOException {
StringBuilder result = new StringBuilder();
boolean quoted = false;
int c = skipLws(input, false);
if (c == '"') {
quoted = true;
} else if (c == -1 || !isToken(c)) {
return null;
} else {
result.append((char) c);
}
c = input.read();
while (c != -1 && isToken(c)) {
result.append((char) c);
c = input.read();
}
if (quoted) {
if (c != '"') {
return null;
}
} else {
// Skip back so non-token character is available for next read
input.skip(-1);
}
if (c != -1 && result.length() == 0) {
return null;
} else {
return result.toString();
}
}
/**
* LHEX can be read unambiguously with or without surrounding quotes so this
* parsing method for LHEX permits optional surrounding double quotes. Some
* buggy clients (libwww-perl for DIGEST auth) are known to send quoted LHEX
* when the specification requires just LHEX.
*
*
* LHEX are, literally, lower-case hexadecimal digits. This implementation
* allows for upper-case digits as well, converting the returned value to
* lower-case.
*
* @return the sequence of LHEX (minus any surrounding quotes) if any was
* found, or null if data other LHEX was found
*/
private static String readLhex(StringReader input)
throws IOException {
StringBuilder result = new StringBuilder();
boolean quoted = false;
int c = skipLws(input, false);
if (c == '"') {
quoted = true;
} else if (c == -1 || !isHex(c)) {
return null;
} else {
if ('A' <= c && c <= 'F') {
c -= ('A' - 'a');
}
result.append((char) c);
}
c = input.read();
while (c != -1 && isHex(c)) {
if ('A' <= c && c <= 'F') {
c -= ('A' - 'a');
}
result.append((char) c);
c = input.read();
}
if (quoted) {
if (c != '"') {
return null;
}
} else {
// Skip back so non-hex character is available for next read
input.skip(-1);
}
if (c != -1 && result.length() == 0) {
return null;
} else {
return result.toString();
}
}
private static enum SkipConstantResult {
FOUND,
NOT_FOUND,
EOF
}
}