/*
* 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 libcore.net;
import java.io.ByteArrayOutputStream;
import java.net.URISyntaxException;
import java.nio.charset.Charset;
import java.nio.charset.Charsets;
/**
* Encodes and decodes {@code application/x-www-form-urlencoded} content.
* Subclasses define exactly which characters are legal.
*
* <p>By default, UTF-8 is used to encode escaped characters. A single input
* character like "\u0080" may be encoded to multiple octets like %C2%80.
*/
public abstract class UriCodec {
/**
* Returns true if {@code c} does not need to be escaped.
*/
protected abstract boolean isRetained(char c);
/**
* Throws if {@code s} is invalid according to this encoder.
*/
public final String validate(String uri, int start, int end, String name)
throws URISyntaxException {
for (int i = start; i < end; ) {
char ch = uri.charAt(i);
if ((ch >= 'a' && ch <= 'z')
|| (ch >= 'A' && ch <= 'Z')
|| (ch >= '0' && ch <= '9')
|| isRetained(ch)) {
i++;
} else if (ch == '%') {
if (i + 2 >= end) {
throw new URISyntaxException(uri, "Incomplete % sequence in " + name, i);
}
int d1 = hexToInt(uri.charAt(i + 1));
int d2 = hexToInt(uri.charAt(i + 2));
if (d1 == -1 || d2 == -1) {
throw new URISyntaxException(uri, "Invalid % sequence: "
+ uri.substring(i, i + 3) + " in " + name, i);
}
i += 3;
} else {
throw new URISyntaxException(uri, "Illegal character in " + name, i);
}
}
return uri.substring(start, end);
}
/**
* Throws if {@code s} contains characters that are not letters, digits or
* in {@code legal}.
*/
public static void validateSimple(String s, String legal)
throws URISyntaxException {
for (int i = 0; i < s.length(); i++) {
char ch = s.charAt(i);
if (!((ch >= 'a' && ch <= 'z')
|| (ch >= 'A' && ch <= 'Z')
|| (ch >= '0' && ch <= '9')
|| legal.indexOf(ch) > -1)) {
throw new URISyntaxException(s, "Illegal character", i);
}
}
}
/**
* Encodes {@code s} and appends the result to {@code builder}.
*
* @param isPartiallyEncoded true to fix input that has already been
* partially or fully encoded. For example, input of "hello%20world" is
* unchanged with isPartiallyEncoded=true but would be double-escaped to
* "hello%2520world" otherwise.
*/
private void appendEncoded(StringBuilder builder, String s, Charset charset,
boolean isPartiallyEncoded) {
if (s == null) {
throw new NullPointerException("s == null");
}
int escapeStart = -1;
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
if ((c >= 'a' && c <= 'z')
|| (c >= 'A' && c <= 'Z')
|| (c >= '0' && c <= '9')
|| isRetained(c)
|| (c == '%' && isPartiallyEncoded)) {
if (escapeStart != -1) {
appendHex(builder, s.substring(escapeStart, i), charset);
escapeStart = -1;
}
if (c == '%' && isPartiallyEncoded) {
// this is an encoded 3-character sequence like "%20"
builder.append(s, i, i + 3);
i += 2;
} else if (c == ' ') {
builder.append('+');
} else {
builder.append(c);
}
} else if (escapeStart == -1) {
escapeStart = i;
}
}
if (escapeStart != -1) {
appendHex(builder, s.substring(escapeStart, s.length()), charset);
}
}
public final String encode(String s, Charset charset) {
// Guess a bit larger for encoded form
StringBuilder builder = new StringBuilder(s.length() + 16);
appendEncoded(builder, s, charset, false);
return builder.toString();
}
public final void appendEncoded(StringBuilder builder, String s) {
appendEncoded(builder, s, Charsets.UTF_8, false);
}
public final void appendPartiallyEncoded(StringBuilder builder, String s) {
appendEncoded(builder, s, Charsets.UTF_8, true);
}
/**
* @param convertPlus true to convert '+' to ' '.
* @param throwOnFailure true to throw an IllegalArgumentException on
* invalid escape sequences; false to replace them with the replacement
* character (U+fffd).
*/
public static String decode(String s, boolean convertPlus, Charset charset,
boolean throwOnFailure) {
if (s.indexOf('%') == -1 && (!convertPlus || s.indexOf('+') == -1)) {
return s;
}
StringBuilder result = new StringBuilder(s.length());
ByteArrayOutputStream out = new ByteArrayOutputStream();
for (int i = 0; i < s.length();) {
char c = s.charAt(i);
if (c == '%') {
do {
int d1, d2;
if (i + 2 < s.length()
&& (d1 = hexToInt(s.charAt(i + 1))) != -1
&& (d2 = hexToInt(s.charAt(i + 2))) != -1) {
out.write((byte) ((d1 << 4) + d2));
} else if (throwOnFailure) {
throw new IllegalArgumentException("Invalid % sequence at " + i + ": " + s);
} else {
byte[] replacement = "\ufffd".getBytes(charset);
out.write(replacement, 0, replacement.length);
}
i += 3;
} while (i < s.length() && s.charAt(i) == '%');
result.append(new String(out.toByteArray(), charset));
out.reset();
} else {
if (convertPlus && c == '+') {
c = ' ';
}
result.append(c);
i++;
}
}
return result.toString();
}
/**
* Like {@link Character#digit}, but without support for non-ASCII
* characters.
*/
private static int hexToInt(char c) {
if ('0' <= c && c <= '9') {
return c - '0';
} else if ('a' <= c && c <= 'f') {
return 10 + (c - 'a');
} else if ('A' <= c && c <= 'F') {
return 10 + (c - 'A');
} else {
return -1;
}
}
public static String decode(String s) {
return decode(s, false, Charsets.UTF_8, true);
}
private static void appendHex(StringBuilder builder, String s, Charset charset) {
for (byte b : s.getBytes(charset)) {
appendHex(builder, b);
}
}
private static void appendHex(StringBuilder sb, byte b) {
sb.append('%');
sb.append(Byte.toHexString(b, true));
}
}