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* Base64:

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- Catch numerous decoding errors that were previously misdecoded (ticket #1318)
  - Improve decoding efficiency, reduce copies
  - encode(String) now uses UTF-8 encoding
  - decode() now accepts short strings without trailing '='
  - whitespace in decode will now cause an error, was previously ignored
  - Cleanups
This commit is contained in:
zzz
2014-07-03 13:03:56 +00:00
parent 75ff7987b8
commit 8198c83982
1 changed files with 168 additions and 105 deletions
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273
core/java/src/net/i2p/data/Base64.java
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@@ -42,13 +42,17 @@ public class Base64 {
//private final static Log _log = new Log(Base64.class);
/**
* Output will be a multiple of 4 chars, including 0-2 trailing '='
* As of 0.9.14, encodes the UTF-8 encoding of source. Prior to that, used the platform's encoding.
*
* @param source if null will return ""
*/
public static String encode(String source) {
return (source != null ? encode(source.getBytes()) : "");
return (source != null ? encode(DataHelper.getUTF8(source)) : "");
}
/**
* Output will be a multiple of 4 chars, including 0-2 trailing '='
* @param source if null will return ""
*/
public static String encode(byte[] source) {
@@ -56,6 +60,7 @@ public class Base64 {
}
/**
* Output will be a multiple of 4 chars, including 0-2 trailing '='
* @param source if null will return ""
*/
public static String encode(byte[] source, int off, int len) {
@@ -63,6 +68,7 @@ public class Base64 {
}
/**
* Output will be a multiple of 4 chars, including 0-2 trailing '='
* @param source if null will return ""
* @param useStandardAlphabet Warning, must be false for I2P compatibility
*/
@@ -71,6 +77,7 @@ public class Base64 {
}
/**
* Output will be a multiple of 4 chars, including 0-2 trailing '='
* @param source if null will return ""
* @param useStandardAlphabet Warning, must be false for I2P compatibility
*/
@@ -79,7 +86,17 @@ public class Base64 {
}
/**
* Decodes data from Base64 notation.
* Decodes data from Base64 notation using the I2P alphabet.
*
* As of 0.9.14, does not require trailing '=' if remaining bits are zero.
* Prior to that, trailing 1, 2, or 3 chars were ignored.
*
* As of 0.9.14, trailing garbage after an '=' will cause an error.
* Prior to that, it was ignored.
*
* As of 0.9.14, whitespace will cause an error.
* Prior to that, it was ignored.
*
* @param s Base 64 encoded string using the I2P alphabet A-Z, a-z, 0-9, -, ~
* @return the decoded data, null on error
*/
@@ -122,6 +139,7 @@ public class Base64 {
/**
* Translates a Base64 value to either its 6-bit reconstruction value
* or a negative number indicating some other meaning.
* As of 0.9.14 this is the decoding for the I2P alphabet. See safeDecode().
**/
private final static byte[] DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8
-5, -5, // Whitespace: Tab and Linefeed
@@ -131,9 +149,8 @@ public class Base64 {
-9, -9, -9, -9, -9, // Decimal 27 - 31
-5, // Whitespace: Space
-9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
62, // Plus sign at decimal 43
-9, -9, -9, // Decimal 44 - 46
63, // Slash at decimal 47
//62, -9, -9, -9, 63, // + , - . / (43-47) NON-I2P
-9, -9, 62, -9, -9, // + , - . / (43-47) I2P
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
-9, -9, -9, // Decimal 58 - 60
-1, // Equals sign at decimal 61
@@ -143,8 +160,9 @@ public class Base64 {
-9, -9, -9, -9, -9, -9, // Decimal 91 - 96
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
-9, -9, -9, -9 // Decimal 123 - 126
/*,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 127 - 139
//-9, -9, -9, -9 // Decimal 123 - 126 (126 is '~') NON-I2P
-9, -9, -9, 63 // Decimal 123 - 126 (126 is '~') I2P
,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 127 - 139
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 140 - 152
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178
@@ -153,9 +171,10 @@ public class Base64 {
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 218 - 230
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255 */
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
};
private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding
private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding
@@ -167,7 +186,6 @@ public class Base64 {
//test();
if (args.length == 0) {
help();
return;
}
runApp(args);
}
@@ -175,22 +193,36 @@ public class Base64 {
private static void runApp(String args[]) {
String cmd = args[0].toLowerCase(Locale.US);
if ("encodestring".equals(cmd)) {
System.out.println(encode(args[1].getBytes()));
if (args.length != 2)
help();
System.out.println(encode(DataHelper.getUTF8(args[1])));
return;
}
if ("decodestring".equals(cmd)) {
if (args.length != 2)
help();
byte[] dec = decode(args[1]);
if (dec != null) {
try {
System.out.write(dec);
} catch (IOException ioe) {
System.err.println("output error " + ioe);
System.exit(1);
}
} else {
System.err.println("decode error");
System.exit(1);
}
return;
}
if ("test".equals(cmd)) {
System.err.println("test disabled");
System.exit(1);
}
if (!("encode".equals(cmd) || "decode".equals(cmd))) {
System.err.println("unknown command " + cmd);
System.exit(1);
}
InputStream in = System.in;
OutputStream out = System.out;
try {
@@ -202,11 +234,8 @@ public class Base64 {
}
if ("encode".equals(cmd)) {
encode(in, out);
return;
}
if ("decode".equals(cmd)) {
} else {
decode(in, out);
return;
}
} catch (IOException ioe) {
ioe.printStackTrace(System.err);
@@ -238,16 +267,18 @@ public class Base64 {
out.write(decoded);
}
/** exits 1, never returns */
private static void help() {
System.out.println("Syntax: Base64 encode <inFile> <outFile>");
System.out.println("or : Base64 encode <inFile>");
System.out.println("or : Base64 encode");
System.out.println("or : Base64 decode <inFile> <outFile>");
System.out.println("or : Base64 decode <inFile>");
System.out.println("or : Base64 decode");
System.out.println("or : Base64 encodestring 'string to encode'");
System.out.println("or : Base64 decodestring 'string to decode'");
System.out.println("or : Base64 test");
System.err.println("Usage: Base64 encode <inFile> <outFile>");
System.err.println(" Base64 encode <inFile>");
System.err.println(" Base64 encode (stdin to stdout)");
System.err.println(" Base64 decode <inFile> <outFile>");
System.err.println(" Base64 decode <inFile>");
System.err.println(" Base64 decode (stdin to stdout)");
System.err.println(" Base64 encodestring 'string to encode'");
System.err.println(" Base64 decodestring 'string to decode'");
System.err.println(" Base64 test");
System.exit(1);
}
/*******
@@ -458,12 +489,15 @@ public class Base64 {
*/
private static byte[] safeDecode(String source, boolean useStandardAlphabet) {
if (source == null) return null;
String toDecode = null;
String toDecode;
if (useStandardAlphabet) {
toDecode = source;
//toDecode = source;
toDecode = source.replace('/', '~');
toDecode = toDecode.replace('+', '-');
} else {
toDecode = source.replace('~', '/');
toDecode = toDecode.replace('-', '+');
//toDecode = source.replace('~', '/');
//toDecode = toDecode.replace('-', '+');
toDecode = source;
}
return standardDecode(toDecode);
}
@@ -600,76 +634,75 @@ public class Base64 {
* @param srcOffset the index where conversion begins
* @param destination the array to hold the conversion
* @param destOffset the index where output will be put
* @return the number of decoded bytes converted
* @return the number of decoded bytes converted 1-3, or -1 on error, never zero
* @since 1.3
*/
private static int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset) {
// Example: Dk==
if (source[srcOffset + 2] == EQUALS_SIGN) {
// Two ways to do the same thing. Don't know which way I like best.
//int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
// | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18)
| ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12);
byte decode0 = DECODABET[source[srcOffset++]];
byte decode1 = DECODABET[source[srcOffset++]];
if (decode0 < 0 || decode1 < 0)
return -1;
destination[destOffset] = (byte) (outBuff >>> 16);
// Example: Dk==
if (source[srcOffset] == EQUALS_SIGN) {
if (source[srcOffset + 1] != EQUALS_SIGN)
return -1;
// verify no extra bits
if ((decode1 & 0x0f) != 0)
return -1;
int outBuff = (decode0 << 18)
| (decode1 << 12);
destination[destOffset] = (byte) (outBuff >> 16);
return 1;
}
// Example: DkL=
else if (source[srcOffset + 3] == EQUALS_SIGN) {
// Two ways to do the same thing. Don't know which way I like best.
//int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
// | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
// | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18)
| ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12)
| ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6);
destination[destOffset] = (byte) (outBuff >>> 16);
destination[destOffset + 1] = (byte) (outBuff >>> 8);
else if (source[srcOffset + 1] == EQUALS_SIGN) {
byte decode2 = DECODABET[source[srcOffset]];
if (decode2 < 0)
return -1;
// verify no extra bits
if ((decode2 & 0x03) != 0)
return -1;
int outBuff = (decode0 << 18)
| (decode1 << 12)
| (decode2 << 6);
destination[destOffset++] = (byte) (outBuff >> 16);
destination[destOffset] = (byte) (outBuff >> 8);
return 2;
}
// Example: DkLE
else {
try {
// Two ways to do the same thing. Don't know which way I like best.
//int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
// | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
// | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 )
// | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 );
int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18)
| ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12)
| ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6)
| ((DECODABET[source[srcOffset + 3]] & 0xFF));
destination[destOffset] = (byte) (outBuff >> 16);
destination[destOffset + 1] = (byte) (outBuff >> 8);
destination[destOffset + 2] = (byte) (outBuff);
return 3;
} catch (Exception e) {
System.out.println("" + source[srcOffset] + ": " + (DECODABET[source[srcOffset]]));
System.out.println("" + source[srcOffset + 1] + ": " + (DECODABET[source[srcOffset + 1]]));
System.out.println("" + source[srcOffset + 2] + ": " + (DECODABET[source[srcOffset + 2]]));
System.out.println("" + source[srcOffset + 3] + ": " + (DECODABET[source[srcOffset + 3]]));
byte decode2 = DECODABET[source[srcOffset++]];
byte decode3 = DECODABET[source[srcOffset]];
if (decode2 < 0 || decode3 < 0)
return -1;
} //e nd catch
int outBuff = (decode0 << 18)
| (decode1 << 12)
| (decode2 << 6)
| decode3;
destination[destOffset++] = (byte) (outBuff >> 16);
destination[destOffset++] = (byte) (outBuff >> 8);
destination[destOffset] = (byte) (outBuff);
return 3;
}
} // end decodeToBytes
/**
* Decodes data from Base64 notation.
* As of 0.9.14, this uses the I2P alphabet, so it is not "standard".
*
* @param s the string to decode
* @return the decoded data, null on error
* @since 1.4
*/
private static byte[] standardDecode(String s) {
byte[] bytes = new byte[s.length()];
for (int i = 0; i < bytes.length; i++)
bytes[i] = (byte)(s.charAt(i) & 0xFF);
// We use getUTF8() instead of getASCII() so we may verify
// there's no UTF-8 in there.
byte[] bytes = DataHelper.getUTF8(s);
if (bytes.length != s.length())
return null;
return decode(bytes, 0, bytes.length);
} // end decode
@@ -678,21 +711,43 @@ public class Base64 {
* returns it as a string.
* Equivlaent to calling
* <code>new String( decode( s ) )</code>
* WARNING this uses the locale's encoding, it may not be what you want.
*
* As of 0.9.14, decodes as UTF-8. Prior to that, it used the platform's encoding.
* For best results, decoded data should be 7 bit.
*
* As of 0.9.14, does not require trailing '=' if remaining bits are zero.
* Prior to that, trailing 1, 2, or 3 chars were ignored.
*
* As of 0.9.14, trailing garbage after an '=' will cause an error.
* Prior to that, it was ignored.
*
* As of 0.9.14, whitespace will cause an error.
* Prior to that, it was ignored.
*
* @param s the strind to decode
* @return The data as a string
* @return The data as a string, or null on error
* @since 1.4
* @throws NPE on error?
*/
public static String decodeToString(String s) {
return new String(decode(s));
byte[] b = decode(s);
if (b == null)
return null;
return DataHelper.getUTF8(b);
} // end decodeToString
/**
* Decodes Base64 content in byte array format and returns
* the decoded byte array.
*
* As of 0.9.14, does not require trailing '=' if remaining bits are zero.
* Prior to that, trailing 1, 2, or 3 chars were ignored.
*
* As of 0.9.14, trailing garbage after an '=' will cause an error.
* Prior to that, it was ignored.
*
* As of 0.9.14, whitespace will cause an error.
* Prior to that, it was ignored.
*
* @param source The Base64 encoded data
* @param off The offset of where to begin decoding
* @param len The length of characters to decode
@@ -701,39 +756,47 @@ public class Base64 {
*/
private static byte[] decode(byte[] source, int off, int len) {
int len34 = len * 3 / 4;
byte[] outBuff = new byte[len34]; // Upper limit on size of output
byte[] outBuff = new byte[len34]; // size of output
int outBuffPosn = 0;
byte[] b4 = new byte[4];
int b4Posn = 0;
int i = 0;
byte sbiCrop = 0;
byte sbiDecode = 0;
for (i = 0; i < len; i++) {
sbiCrop = (byte) (source[i] & 0x7f); // Only the low seven bits
sbiDecode = DECODABET[sbiCrop];
if (sbiDecode >= WHITE_SPACE_ENC) // White space, Equals sign or better
{
if (sbiDecode >= EQUALS_SIGN_ENC) {
b4[b4Posn++] = sbiCrop;
if (b4Posn > 3) {
outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn);
b4Posn = 0;
// If that was the equals sign, break out of 'for' loop
if (sbiCrop == EQUALS_SIGN) break;
} // end if: quartet built
} // end if: equals sign or better
} // end if: white space, equals sign or better
else {
//_log.warn("Bad Base64 input character at " + i + ": " + source[i] + "(decimal)");
int i = off;
int end = off + len;
int converted = 0;
while (i + 3 < end) {
converted = decode4to3(source, i, outBuff, outBuffPosn);
if (converted < 0)
return null;
} // end else:
} // each input character
outBuffPosn += converted;
i += 4;
if (converted < 3)
break;
}
// process any remaining without '='
int remaining = end - i;
if (remaining > 0) {
if (converted > 0 && converted < 3)
return null;
if (remaining == 1 || remaining > 3)
return null;
byte[] b4 = new byte[4];
b4[0] = source[i++];
b4[1] = source[i++];
if (remaining == 3)
b4[2] = source[i];
else
b4[2] = EQUALS_SIGN;
b4[3] = EQUALS_SIGN;
converted = decode4to3(b4, 0, outBuff, outBuffPosn);
if (converted < 0)
return null;
outBuffPosn += converted;
}
// don't copy unless we have to
if (outBuffPosn == outBuff.length)
return outBuff;
// and we shouldn't ever... would have returned null before
byte[] out = new byte[outBuffPosn];
System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
return out;