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package org.xbib.io.ftp.client;
import java.io.UnsupportedEncodingException;
/**
* Provides Base64 encoding and decoding as defined by RFC 2045.
* This class implements section 6.8. Base64 Content-Transfer-Encoding from RFC 2045 Multipurpose
* Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies by Freed and Borenstein.
* The class can be parameterized in the following manner with various constructors:
*
* - URL-safe mode: Default off.
* - Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of
* 4 in the encoded data.
*
- Line separator: Default is CRLF ("\r\n")
*
* Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
* character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
*
* @see RFC 2045
*/
public class Base64 {
/**
* Chunk size per RFC 2045 section 6.8.
*
*
* The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
* equal signs.
*
*
* @see RFC 2045 section 6.8
*/
static final int CHUNK_SIZE = 76;
private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
private static final int DEFAULT_BUFFER_SIZE = 8192;
/**
* Chunk separator per RFC 2045 section 2.1.
*
* @see RFC 2045 section 2.1
*/
private static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
/**
* This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
* equivalents as specified in Table 1 of RFC 2045.
*
* Thanks to "commons" project in ws.apache.org for this code.
* http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*/
private static final byte[] STANDARD_ENCODE_TABLE = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};
/**
* This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
* changed to - and _ to make the encoded Base64 results more URL-SAFE.
* This table is only used when the Base64's mode is set to URL-SAFE.
*/
private static final byte[] URL_SAFE_ENCODE_TABLE = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
};
/**
* Byte used to pad output.
*/
private static final byte PAD = '=';
/**
* This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
* Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in the Base64
* alphabet but fall within the bounds of the array are translated to -1.
*
* Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both
* URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).
*
* Thanks to "commons" project in ws.apache.org for this code.
* http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*/
private static final byte[] DECODE_TABLE = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54,
55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
};
/**
* Mask used to extract 6 bits, used when encoding
*/
private static final int MASK_6BITS = 0x3f;
/**
* Mask used to extract 8 bits, used in decoding base64 bytes
*/
private static final int MASK_8BITS = 0xff;
// The static final fields above are used for the original static byte[] methods on Base64.
// The private member fields below are used with the new streaming approach, which requires
// some state be preserved between calls of encode() and decode().
/**
* Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able
* to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch
* between the two modes.
*/
private final byte[] encodeTable;
/**
* Line length for encoding. Not used when decoding. A value of zero or less implies no chunking of the base64
* encoded data.
*/
private final int lineLength;
/**
* Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
*/
private final byte[] lineSeparator;
/**
* Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
* decodeSize = 3 + lineSeparator.length;
*/
private final int decodeSize;
/**
* Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
* encodeSize = 4 + lineSeparator.length;
*/
private final int encodeSize;
/**
* Buffer for streaming.
*/
private byte[] buffer;
/**
* Position where next character should be written in the buffer.
*/
private int pos;
/**
* Position where next character should be read from the buffer.
*/
private int readPos;
/**
* Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to
* make sure each encoded line never goes beyond lineLength (if lineLength > 0).
*/
private int currentLinePos;
/**
* Writes to the buffer only occur after every 3 reads when encoding, an every 4 reads when decoding. This variable
* helps track that.
*/
private int modulus;
/**
* Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this Base64 object becomes useless,
* and must be thrown away.
*/
private boolean eof;
/**
* Place holder for the 3 bytes we're dealing with for our base64 logic. Bitwise operations store and extract the
* base64 encoding or decoding from this variable.
*/
private int x;
/**
* Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
* When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
* When decoding all variants are supported.
*/
public Base64() {
this(false);
}
/**
* Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
* When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
* When decoding all variants are supported.
*
* @param urlSafe if true, URL-safe encoding is used. In most cases this should be set to
* false.
*/
public Base64(boolean urlSafe) {
this(CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
}
/**
* Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
*
* When encoding the line length and line separator are given in the constructor, and the encoding table is
* STANDARD_ENCODE_TABLE.
*
*
* Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
*
*
* When decoding all variants are supported.
*
*
* @param lineLength Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
* If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored when decoding.
* @param lineSeparator Each line of encoded data will end with this sequence of bytes.
* @param urlSafe Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode
* operations. Decoding seamlessly handles both modes.
* @throws IllegalArgumentException The provided lineSeparator included some base64 characters. That's not going to work!
*/
public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe) {
if (lineSeparator == null) {
lineLength = 0; // disable chunk-separating
lineSeparator = EMPTY_BYTE_ARRAY; // this just gets ignored
}
this.lineLength = lineLength > 0 ? (lineLength / 4) * 4 : 0;
this.lineSeparator = new byte[lineSeparator.length];
System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
if (lineLength > 0) {
this.encodeSize = 4 + lineSeparator.length;
} else {
this.encodeSize = 4;
}
this.decodeSize = this.encodeSize - 1;
if (containsBase64Byte(lineSeparator)) {
String sep = newStringUtf8(lineSeparator);
throw new IllegalArgumentException("lineSeperator must not contain base64 characters: [" + sep + "]");
}
this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
}
/**
* Returns whether or not the octet is in the base 64 alphabet.
*
* @param octet The value to test
* @return true if the value is defined in the the base 64 alphabet, false otherwise.
*/
public static boolean isBase64(byte octet) {
return octet == PAD || (octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1);
}
/**
* Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
*
* @param arrayOctet byte array to test
* @return true if any byte is a valid character in the Base64 alphabet; false herwise
*/
private static boolean containsBase64Byte(byte[] arrayOctet) {
for (byte element : arrayOctet) {
if (isBase64(element)) {
return true;
}
}
return false;
}
/**
* Encodes binary data using the base64 algorithm, without using chunking.
*
* @param binaryData binary data to encode
* @return String containing Base64 characters.
*/
public static String encodeBase64StringUnChunked(byte[] binaryData) {
return newStringUtf8(encodeBase64(binaryData, false));
}
/**
* Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if true this encoder will chunk the base64 output into 76 character blocks
* @return Base64-encoded data.
* @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
*/
public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
return encodeBase64(binaryData, isChunked, false);
}
/**
* Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if true this encoder will chunk the base64 output into 76 character blocks
* @param urlSafe if true this encoder will emit - and _ instead of the usual + and / characters.
* @return Base64-encoded data.
* @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
*/
public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe) {
return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
}
/**
* Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if true this encoder will chunk the base64 output into 76 character blocks
* @param urlSafe if true this encoder will emit - and _ instead of the usual + and / characters.
* @param maxResultSize The maximum result size to accept.
* @return Base64-encoded data.
* @throws IllegalArgumentException Thrown when the input array needs an output array bigger than maxResultSize
*/
public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe, int maxResultSize) {
if (binaryData == null || binaryData.length == 0) {
return binaryData;
}
long len = getEncodeLength(binaryData, isChunked ? CHUNK_SIZE : 0, isChunked ? CHUNK_SEPARATOR : EMPTY_BYTE_ARRAY);
if (len > maxResultSize) {
throw new IllegalArgumentException("Input array too big, the output array would be bigger (" +
len +
") than the specified maxium size of " +
maxResultSize);
}
Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
return b64.encode(binaryData);
}
/**
* Decodes a Base64 String into octets
*
* @param base64String String containing Base64 data
* @return Array containing decoded data.
*/
public static byte[] decodeBase64(String base64String) {
return new Base64().decode(base64String);
}
private static String newStringUtf8(byte[] encode) {
String str = null;
try {
str = new String(encode, "UTF8");
} catch (UnsupportedEncodingException ue) {
throw new RuntimeException(ue);
}
return str;
}
/**
* Pre-calculates the amount of space needed to base64-encode the supplied array.
*
* @param pArray byte[] array which will later be encoded
* @param chunkSize line-length of the output (<= 0 means no chunking) between each
* chunkSeparator (e.g. CRLF).
* @param chunkSeparator the sequence of bytes used to separate chunks of output (e.g. CRLF).
* @return amount of space needed to encoded the supplied array. Returns
* a long since a max-len array will require Integer.MAX_VALUE + 33%.
*/
private static long getEncodeLength(byte[] pArray, int chunkSize, byte[] chunkSeparator) {
// base64 always encodes to multiples of 4.
chunkSize = (chunkSize / 4) * 4;
long len = (pArray.length * 4) / 3;
long mod = len % 4;
if (mod != 0) {
len += 4 - mod;
}
if (chunkSize > 0) {
boolean lenChunksPerfectly = len % chunkSize == 0;
len += (len / chunkSize) * chunkSeparator.length;
if (!lenChunksPerfectly) {
len += chunkSeparator.length;
}
}
return len;
}
/**
* Returns our current encode mode. True if we're URL-SAFE, false otherwise.
*
* @return true if we're in URL-SAFE mode, false otherwise.
*/
public boolean isUrlSafe() {
return this.encodeTable == URL_SAFE_ENCODE_TABLE;
}
/**
* Returns the amount of buffered data available for reading.
*
* @return The amount of buffered data available for reading.
*/
int avail() {
return buffer != null ? pos - readPos : 0;
}
/**
* Doubles our buffer.
*/
private void resizeBuffer() {
if (buffer == null) {
buffer = new byte[DEFAULT_BUFFER_SIZE];
pos = 0;
readPos = 0;
} else {
byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
System.arraycopy(buffer, 0, b, 0, buffer.length);
buffer = b;
}
}
/**
* Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
* bytes. Returns how many bytes were actually extracted.
*
* @param b byte[] array to extract the buffered data into.
* @param bPos position in byte[] array to start extraction at.
* @param bAvail amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
* @return The number of bytes successfully extracted into the provided byte[] array.
*/
int readResults(byte[] b, int bPos, int bAvail) {
if (buffer != null) {
int len = Math.min(avail(), bAvail);
if (buffer != b) {
System.arraycopy(buffer, readPos, b, bPos, len);
readPos += len;
if (readPos >= pos) {
buffer = null;
}
} else {
// Re-using the original consumer's output array is only
// allowed for one round.
buffer = null;
}
return len;
}
return eof ? -1 : 0;
}
/**
* Sets the streaming buffer. This is a small optimization where we try to buffer directly to the consumer's output
* array for one round (if the consumer calls this method first) instead of starting our own buffer.
*
* @param out byte[] array to buffer directly to.
* @param outPos Position to start buffering into.
* @param outAvail Amount of bytes available for direct buffering.
*/
void setInitialBuffer(byte[] out, int outPos, int outAvail) {
// We can re-use consumer's original output array under
// special circumstances, saving on some System.arraycopy().
if (out != null && out.length == outAvail) {
buffer = out;
pos = outPos;
readPos = outPos;
}
}
/**
*
* Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with
* the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last
* remaining bytes (if not multiple of 3).
*
*
* Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
* http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*
*
* @param in byte[] array of binary data to base64 encode.
* @param inPos Position to start reading data from.
* @param inAvail Amount of bytes available from input for encoding.
*/
void encode(byte[] in, int inPos, int inAvail) {
if (eof) {
return;
}
// inAvail < 0 is how we're informed of EOF in the underlying data we're
// encoding.
if (inAvail < 0) {
eof = true;
if (buffer == null || buffer.length - pos < encodeSize) {
resizeBuffer();
}
switch (modulus) {
case 1:
buffer[pos++] = encodeTable[(x >> 2) & MASK_6BITS];
buffer[pos++] = encodeTable[(x << 4) & MASK_6BITS];
// URL-SAFE skips the padding to further reduce size.
if (encodeTable == STANDARD_ENCODE_TABLE) {
buffer[pos++] = PAD;
buffer[pos++] = PAD;
}
break;
case 2:
buffer[pos++] = encodeTable[(x >> 10) & MASK_6BITS];
buffer[pos++] = encodeTable[(x >> 4) & MASK_6BITS];
buffer[pos++] = encodeTable[(x << 2) & MASK_6BITS];
// URL-SAFE skips the padding to further reduce size.
if (encodeTable == STANDARD_ENCODE_TABLE) {
buffer[pos++] = PAD;
}
break;
default:
break; // other values ignored
}
if (lineLength > 0 && pos > 0) {
System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
pos += lineSeparator.length;
}
} else {
for (int i = 0; i < inAvail; i++) {
if (buffer == null || buffer.length - pos < encodeSize) {
resizeBuffer();
}
modulus = (++modulus) % 3;
int b = in[inPos++];
if (b < 0) {
b += 256;
}
x = (x << 8) + b;
if (0 == modulus) {
buffer[pos++] = encodeTable[(x >> 18) & MASK_6BITS];
buffer[pos++] = encodeTable[(x >> 12) & MASK_6BITS];
buffer[pos++] = encodeTable[(x >> 6) & MASK_6BITS];
buffer[pos++] = encodeTable[x & MASK_6BITS];
currentLinePos += 4;
if (lineLength > 0 && lineLength <= currentLinePos) {
System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
pos += lineSeparator.length;
currentLinePos = 0;
}
}
}
}
}
/**
*
* Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once
* with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1"
* call is not necessary when decoding, but it doesn't hurt, either.
*
*
* Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
* silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
* garbage-out philosophy: it will not check the provided data for validity.
*
*
* Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
* http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*
*
* @param in byte[] array of ascii data to base64 decode.
* @param inPos Position to start reading data from.
* @param inAvail Amount of bytes available from input for encoding.
*/
void decode(byte[] in, int inPos, int inAvail) {
if (eof) {
return;
}
if (inAvail < 0) {
eof = true;
}
for (int i = 0; i < inAvail; i++) {
if (buffer == null || buffer.length - pos < decodeSize) {
resizeBuffer();
}
byte b = in[inPos++];
if (b == PAD) {
// We're done.
eof = true;
break;
} else {
if (b >= 0 && b < DECODE_TABLE.length) {
int result = DECODE_TABLE[b];
if (result >= 0) {
modulus = (++modulus) % 4;
x = (x << 6) + result;
if (modulus == 0) {
buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
buffer[pos++] = (byte) (x & MASK_8BITS);
}
}
}
}
}
// Two forms of EOF as far as base64 decoder is concerned: actual
// EOF (-1) and first time '=' character is encountered in stream.
// This approach makes the '=' padding characters completely optional.
if (eof && modulus != 0) {
x = x << 6;
switch (modulus) {
case 2:
x = x << 6;
buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
break;
case 3:
buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
break;
default:
break; // other values ignored
}
}
}
/**
* Decodes a String containing containing characters in the Base64 alphabet.
*
* @param pArray A String containing Base64 character data
* @return a byte array containing binary data
*/
public byte[] decode(String pArray) {
return decode(getBytesUtf8(pArray));
}
private byte[] getBytesUtf8(String pArray) {
try {
return pArray.getBytes("UTF8");
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e);
}
}
// Implementation of integer encoding used for crypto
/**
* Decodes a byte[] containing containing characters in the Base64 alphabet.
*
* @param pArray A byte array containing Base64 character data
* @return a byte array containing binary data
*/
public byte[] decode(byte[] pArray) {
reset();
if (pArray == null || pArray.length == 0) {
return pArray;
}
long len = (pArray.length * 3) / 4;
byte[] buf = new byte[(int) len];
setInitialBuffer(buf, 0, buf.length);
decode(pArray, 0, pArray.length);
decode(pArray, 0, -1); // Notify decoder of EOF.
// Would be nice to just return buf (like we sometimes do in the encode
// logic), but we have no idea what the line-length was (could even be
// variable). So we cannot determine ahead of time exactly how big an
// array is necessary. Hence the need to construct a 2nd byte array to
// hold the final result:
byte[] result = new byte[pos];
readResults(result, 0, result.length);
return result;
}
/**
* Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64 alphabet.
*
* @param pArray a byte array containing binary data
* @return A byte array containing only Base64 character data
*/
public byte[] encode(byte[] pArray) {
reset();
if (pArray == null || pArray.length == 0) {
return pArray;
}
long len = getEncodeLength(pArray, lineLength, lineSeparator);
byte[] buf = new byte[(int) len];
setInitialBuffer(buf, 0, buf.length);
encode(pArray, 0, pArray.length);
encode(pArray, 0, -1); // Notify encoder of EOF.
// Encoder might have resized, even though it was unnecessary.
if (buffer != buf) {
readResults(buf, 0, buf.length);
}
// In URL-SAFE mode we skip the padding characters, so sometimes our
// final length is a bit smaller.
if (isUrlSafe() && pos < buf.length) {
byte[] smallerBuf = new byte[pos];
System.arraycopy(buf, 0, smallerBuf, 0, pos);
buf = smallerBuf;
}
return buf;
}
/**
* Resets this Base64 object to its initial newly constructed state.
*/
private void reset() {
buffer = null;
pos = 0;
readPos = 0;
currentLinePos = 0;
modulus = 0;
eof = false;
}
}