/*
* Copyright 2011 The Netty Project
*
* The Netty Project 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.jboss.netty.handler.codec.http;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URLDecoder;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.jboss.netty.util.CharsetUtil;
/**
* Splits an HTTP query string into a path string and key-value parameter pairs.
* This decoder is for one time use only. Create a new instance for each URI:
* <pre>
* {@link QueryStringDecoder} decoder = new {@link QueryStringDecoder}("/hello?recipient=world&x=1;y=2");
* assert decoder.getPath().equals("/hello");
* assert decoder.getParameters().get("recipient").get(0).equals("world");
* assert decoder.getParameters().get("x").get(0).equals("1");
* assert decoder.getParameters().get("y").get(0).equals("2");
* </pre>
*
* This decoder can also decode the content of an HTTP POST request whose
* content type is <tt>application/x-www-form-urlencoded</tt>:
* <pre>
* {@link QueryStringDecoder} decoder = new {@link QueryStringDecoder}("recipient=world&x=1;y=2", false);
* ...
* </pre>
*
* <h3>HashDOS vulnerability fix</h3>
*
* As a workaround to the <a href="http://events.ccc.de/congress/2011/Fahrplan/attachments/2007_28C3_Effective_DoS_on_web_application_platforms.pdf">HashDOS</a>
* vulnerability, the decoder limits the maximum number of decoded key-value
* parameter pairs, up to {@literal 1024} by default, and you can configure it
* when you construct the decoder by passing an additional integer parameter.
*
* @see QueryStringEncoder
*
* @apiviz.stereotype utility
* @apiviz.has org.jboss.netty.handler.codec.http.HttpRequest oneway - - decodes
*/
public class QueryStringDecoder {
private static final int DEFAULT_MAX_PARAMS = 1024;
private final Charset charset;
private final String uri;
private final boolean hasPath;
private final int maxParams;
private String path;
private Map<String, List<String>> params;
private int nParams;
/**
* Creates a new decoder that decodes the specified URI. The decoder will
* assume that the query string is encoded in UTF-8.
*/
public QueryStringDecoder(String uri) {
this(uri, HttpCodecUtil.DEFAULT_CHARSET);
}
/**
* Creates a new decoder that decodes the specified URI encoded in the
* specified charset.
*/
public QueryStringDecoder(String uri, boolean hasPath) {
this(uri, HttpCodecUtil.DEFAULT_CHARSET, hasPath);
}
/**
* Creates a new decoder that decodes the specified URI encoded in the
* specified charset.
*/
public QueryStringDecoder(String uri, Charset charset) {
this(uri, charset, true);
}
/**
* Creates a new decoder that decodes the specified URI encoded in the
* specified charset.
*/
public QueryStringDecoder(String uri, Charset charset, boolean hasPath) {
this(uri, charset, hasPath, DEFAULT_MAX_PARAMS);
}
/**
* Creates a new decoder that decodes the specified URI encoded in the
* specified charset.
*/
public QueryStringDecoder(String uri, Charset charset, boolean hasPath, int maxParams) {
if (uri == null) {
throw new NullPointerException("uri");
}
if (charset == null) {
throw new NullPointerException("charset");
}
if (maxParams <= 0) {
throw new IllegalArgumentException(
"maxParams: " + maxParams + " (expected: a positive integer)");
}
// http://en.wikipedia.org/wiki/Query_string
this.uri = uri.replace(';', '&');
this.charset = charset;
this.maxParams = maxParams;
this.hasPath = hasPath;
}
/**
* @deprecated Use {@link #QueryStringDecoder(String, Charset)} instead.
*/
@Deprecated
public QueryStringDecoder(String uri, String charset) {
this(uri, Charset.forName(charset));
}
/**
* Creates a new decoder that decodes the specified URI. The decoder will
* assume that the query string is encoded in UTF-8.
*/
public QueryStringDecoder(URI uri) {
this(uri, HttpCodecUtil.DEFAULT_CHARSET);
}
/**
* Creates a new decoder that decodes the specified URI encoded in the
* specified charset.
*/
public QueryStringDecoder(URI uri, Charset charset) {
this(uri, charset, DEFAULT_MAX_PARAMS);
}
/**
* Creates a new decoder that decodes the specified URI encoded in the
* specified charset.
*/
public QueryStringDecoder(URI uri, Charset charset, int maxParams) {
if (uri == null) {
throw new NullPointerException("uri");
}
if (charset == null) {
throw new NullPointerException("charset");
}
if (maxParams <= 0) {
throw new IllegalArgumentException(
"maxParams: " + maxParams + " (expected: a positive integer)");
}
String rawPath = uri.getRawPath();
if (rawPath != null) {
hasPath = true;
} else {
rawPath = "";
hasPath = false;
}
// Also take care of cut of things like "http://localhost"
String newUri = rawPath + "?" + uri.getRawQuery();
// http://en.wikipedia.org/wiki/Query_string
this.uri = newUri.replace(';', '&');
this.charset = charset;
this.maxParams = maxParams;
}
/**
* @deprecated Use {@link #QueryStringDecoder(URI, Charset)} instead.
*/
@Deprecated
public QueryStringDecoder(URI uri, String charset) {
this(uri, Charset.forName(charset));
}
/**
* Returns the decoded path string of the URI.
*/
public String getPath() {
if (path == null) {
if (!hasPath) {
return path = "";
}
int pathEndPos = uri.indexOf('?');
if (pathEndPos < 0) {
path = uri;
} else {
return path = uri.substring(0, pathEndPos);
}
}
return path;
}
/**
* Returns the decoded key-value parameter pairs of the URI.
*/
public Map<String, List<String>> getParameters() {
if (params == null) {
if (hasPath) {
int pathLength = getPath().length();
if (uri.length() == pathLength) {
return Collections.emptyMap();
}
decodeParams(uri.substring(pathLength + 1));
} else {
if (uri.length() == 0) {
return Collections.emptyMap();
}
decodeParams(uri);
}
}
return params;
}
private void decodeParams(String s) {
Map<String, List<String>> params = this.params = new LinkedHashMap<String, List<String>>();
nParams = 0;
String name = null;
int pos = 0; // Beginning of the unprocessed region
int i; // End of the unprocessed region
char c = 0; // Current character
for (i = 0; i < s.length(); i++) {
c = s.charAt(i);
if (c == '=' && name == null) {
if (pos != i) {
name = decodeComponent(s.substring(pos, i), charset);
}
pos = i + 1;
} else if (c == '&') {
if (name == null && pos != i) {
// We haven't seen an `=' so far but moved forward.
// Must be a param of the form '&a&' so add it with
// an empty value.
if (!addParam(params, decodeComponent(s.substring(pos, i), charset), "")) {
return;
}
} else if (name != null) {
if (!addParam(params, name, decodeComponent(s.substring(pos, i), charset))) {
return;
}
name = null;
}
pos = i + 1;
}
}
if (pos != i) { // Are there characters we haven't dealt with?
if (name == null) { // Yes and we haven't seen any `='.
if (!addParam(params, decodeComponent(s.substring(pos, i), charset), "")) {
return;
}
} else { // Yes and this must be the last value.
if (!addParam(params, name, decodeComponent(s.substring(pos, i), charset))) {
return;
}
}
} else if (name != null) { // Have we seen a name without value?
if (!addParam(params, name, "")) {
return;
}
}
}
private boolean addParam(Map<String, List<String>> params, String name, String value) {
if (nParams >= maxParams) {
return false;
}
List<String> values = params.get(name);
if (values == null) {
values = new ArrayList<String>(1); // Often there's only 1 value.
params.put(name, values);
}
values.add(value);
nParams ++;
return true;
}
/**
* Decodes a bit of an URL encoded by a browser.
* <p>
* This is equivalent to calling {@link #decodeComponent(String, Charset)}
* with the UTF-8 charset (recommended to comply with RFC 3986, Section 2).
* @param s The string to decode (can be empty).
* @return The decoded string, or {@code s} if there's nothing to decode.
* If the string to decode is {@code null}, returns an empty string.
* @throws IllegalArgumentException if the string contains a malformed
* escape sequence.
*/
public static String decodeComponent(final String s) {
return decodeComponent(s, HttpCodecUtil.DEFAULT_CHARSET);
}
/**
* Decodes a bit of an URL encoded by a browser.
* <p>
* The string is expected to be encoded as per RFC 3986, Section 2.
* This is the encoding used by JavaScript functions {@code encodeURI}
* and {@code encodeURIComponent}, but not {@code escape}. For example
* in this encoding, é (in Unicode {@code U+00E9} or in UTF-8
* {@code 0xC3 0xA9}) is encoded as {@code %C3%A9} or {@code %c3%a9}.
* <p>
* This is essentially equivalent to calling
* <code>{@link URLDecoder#decode(String, String) URLDecoder.decode}(s, charset.name())</code>
* except that it's over 2x faster and generates less garbage for the GC.
* Actually this function doesn't allocate any memory if there's nothing
* to decode, the argument itself is returned.
* @param s The string to decode (can be empty).
* @param charset The charset to use to decode the string (should really
* be {@link CharsetUtil#UTF_8}.
* @return The decoded string, or {@code s} if there's nothing to decode.
* If the string to decode is {@code null}, returns an empty string.
* @throws IllegalArgumentException if the string contains a malformed
* escape sequence.
*/
@SuppressWarnings("fallthrough")
public static String decodeComponent(final String s,
final Charset charset) {
if (s == null) {
return "";
}
final int size = s.length();
boolean modified = false;
for (int i = 0; i < size; i++) {
final char c = s.charAt(i);
switch (c) {
case '%':
i++; // We can skip at least one char, e.g. `%%'.
// Fall through.
case '+':
modified = true;
break;
}
}
if (!modified) {
return s;
}
final byte[] buf = new byte[size];
int pos = 0; // position in `buf'.
for (int i = 0; i < size; i++) {
char c = s.charAt(i);
switch (c) {
case '+':
buf[pos++] = ' '; // "+" -> " "
break;
case '%':
if (i == size - 1) {
throw new IllegalArgumentException("unterminated escape"
+ " sequence at end of string: " + s);
}
c = s.charAt(++i);
if (c == '%') {
buf[pos++] = '%'; // "%%" -> "%"
break;
} else if (i == size - 1) {
throw new IllegalArgumentException("partial escape"
+ " sequence at end of string: " + s);
}
c = decodeHexNibble(c);
final char c2 = decodeHexNibble(s.charAt(++i));
if (c == Character.MAX_VALUE || c2 == Character.MAX_VALUE) {
throw new IllegalArgumentException(
"invalid escape sequence `%" + s.charAt(i - 1)
+ s.charAt(i) + "' at index " + (i - 2)
+ " of: " + s);
}
c = (char) (c * 16 + c2);
// Fall through.
default:
buf[pos++] = (byte) c;
break;
}
}
try {
return new String(buf, 0, pos, charset.name());
} catch (UnsupportedEncodingException e) {
throw new IllegalArgumentException("unsupported encoding: " + charset.name());
}
}
/**
* Helper to decode half of a hexadecimal number from a string.
* @param c The ASCII character of the hexadecimal number to decode.
* Must be in the range {@code [0-9a-fA-F]}.
* @return The hexadecimal value represented in the ASCII character
* given, or {@link Character#MAX_VALUE} if the character is invalid.
*/
private static char decodeHexNibble(final char c) {
if ('0' <= c && c <= '9') {
return (char) (c - '0');
} else if ('a' <= c && c <= 'f') {
return (char) (c - 'a' + 10);
} else if ('A' <= c && c <= 'F') {
return (char) (c - 'A' + 10);
} else {
return Character.MAX_VALUE;
}
}
}