Coverage Report

Coverage Report - org.apache.commons.codec.binary.Base32

Classes in this File
Line Coverage
Branch Coverage
Complexity
Base32
92%
145/157
83%
59/71
6.75
 /*
  * 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.commons.codec.binary;
 
 /**
  * Provides Base32 encoding and decoding as defined by <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a>.
  *
  * <p>
  * The class can be parameterized in the following manner with various constructors:
  * <ul>
  * <li>Whether to use the "base32hex" variant instead of the default "base32"</li>
  * <li>Line length: Default 76. Line length that aren't multiples of 8 will still essentially end up being multiples of
  * 8 in the encoded data.
  * <li>Line separator: Default is CRLF ("\r\n")</li>
  * </ul>
  * </p>
  * <p>
  * This class operates directly on byte streams, and not character streams.
  * </p>
  * <p>
  * This class is thread-safe.
  * </p>
  *
  * @see <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a>
  *
  * @since 1.5
  * @version $Id$
  */
 public class Base32 extends BaseNCodec {
 
     /**
      * BASE32 characters are 5 bits in length.
      * They are formed by taking a block of five octets to form a 40-bit string,
      * which is converted into eight BASE32 characters.
      */
     private static final int BITS_PER_ENCODED_BYTE = 5;
     private static final int BYTES_PER_ENCODED_BLOCK = 8;
     private static final int BYTES_PER_UNENCODED_BLOCK = 5;
 
     /**
      * Chunk separator per RFC 2045 section 2.1.
      *
      * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
      */
     private static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
 
     /**
      * This array is a lookup table that translates Unicode characters drawn from the "Base32 Alphabet" (as specified
      * in Table 3 of RFC 2045) into their 5-bit positive integer equivalents. Characters that are not in the Base32
      * alphabet but fall within the bounds of the array are translated to -1.
      */
     private static final byte[] DECODE_TABLE = {
          //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 63, // 20-2f
             -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, // 30-3f 2-7
             -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, // 40-4f A-N
             15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,                     // 50-5a O-Z
     };
 
     /**
      * This array is a lookup table that translates 5-bit positive integer index values into their "Base32 Alphabet"
      * equivalents as specified in Table 3 of RFC 2045.
      */
     private static final byte[] 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',
             '2', '3', '4', '5', '6', '7',
     };
 
     /**
      * This array is a lookup table that translates Unicode characters drawn from the "Base32 |Hex Alphabet" (as
      * specified in Table 3 of RFC 2045) into their 5-bit positive integer equivalents. Characters that are not in the
      * Base32 Hex alphabet but fall within the bounds of the array are translated to -1.
      */
     private static final byte[] HEX_DECODE_TABLE = {
          //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 63, // 20-2f
              0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, // 30-3f 2-7
             -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 40-4f A-N
             25, 26, 27, 28, 29, 30, 31, 32,                                 // 50-57 O-V
     };
 
     /**
      * This array is a lookup table that translates 5-bit positive integer index values into their
      * "Base32 Hex Alphabet" equivalents as specified in Table 3 of RFC 2045.
      */
     private static final byte[] HEX_ENCODE_TABLE = {
             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
             'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
             'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
     };
 
     /** Mask used to extract 5 bits, used when encoding Base32 bytes */
     private static final int MASK_5BITS = 0x1f;
 
     // The static final fields above are used for the original static byte[] methods on Base32.
     // The private member fields below are used with the new streaming approach, which requires
     // some state be preserved between calls of encode() and decode().
 
     /**
      * Place holder for the bytes we're dealing with for our based logic.
      * Bitwise operations store and extract the encoding or decoding from this variable.
      */
 
     /**
      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      * <code>decodeSize = {@link #BYTES_PER_ENCODED_BLOCK} - 1 + lineSeparator.length;</code>
      */
     private final int decodeSize;
 
     /**
      * Decode table to use.
      */
     private final byte[] decodeTable;
 
     /**
      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      * <code>encodeSize = {@link #BYTES_PER_ENCODED_BLOCK} + lineSeparator.length;</code>
      */
     private final int encodeSize;
 
     /**
      * Encode table to use.
      */
     private final byte[] encodeTable;
 
     /**
      * Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
      */
     private final byte[] lineSeparator;
 
     /**
      * Creates a Base32 codec used for decoding and encoding.
      * <p>
      * When encoding the line length is 0 (no chunking).
      * </p>
      *
      */
     public Base32() {
         this(false);
     }
 
     /**
      * Creates a Base32 codec used for decoding and encoding.
      * <p>
      * When encoding the line length is 0 (no chunking).
      * </p>
      * @param useHex if {@code true} then use Base32 Hex alphabet
      */
     public Base32(final boolean useHex) {
         this(0, null, useHex);
     }
 
     /**
      * Creates a Base32 codec used for decoding and encoding.
      * <p>
      * When encoding the line length is given in the constructor, the line separator is CRLF.
      * </p>
      *
      * @param lineLength
      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
      *            8). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when
      *            decoding.
      */
     public Base32(final int lineLength) {
         this(lineLength, CHUNK_SEPARATOR);
     }
 
     /**
      * Creates a Base32 codec used for decoding and encoding.
      * <p>
      * When encoding the line length and line separator are given in the constructor.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
      * </p>
      *
      * @param lineLength
      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
      *            8). If 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.
      * @throws IllegalArgumentException
      *             The provided lineSeparator included some Base32 characters. That's not going to work!
      */
     public Base32(final int lineLength, final byte[] lineSeparator) {
         this(lineLength, lineSeparator, false);
     }
 
     /**
      * Creates a Base32 / Base32 Hex codec used for decoding and encoding.
      * <p>
      * When encoding the line length and line separator are given in the constructor.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
      * </p>
      *
      * @param lineLength
      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
      *            8). If 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 useHex
      *            if {@code true}, then use Base32 Hex alphabet, otherwise use Base32 alphabet
      * @throws IllegalArgumentException
      *             The provided lineSeparator included some Base32 characters. That's not going to work! Or the
      *             lineLength > 0 and lineSeparator is null.
      */
     public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex) {
         super(BYTES_PER_UNENCODED_BLOCK, BYTES_PER_ENCODED_BLOCK,
                 lineLength,
                 lineSeparator == null ? 0 : lineSeparator.length);
         if (useHex){
             this.encodeTable = HEX_ENCODE_TABLE;
             this.decodeTable = HEX_DECODE_TABLE;
         } else {
             this.encodeTable = ENCODE_TABLE;
             this.decodeTable = DECODE_TABLE;
         }
         if (lineLength > 0) {
             if (lineSeparator == null) {
                 throw new IllegalArgumentException("lineLength "+lineLength+" > 0, but lineSeparator is null");
             }
             // Must be done after initializing the tables
             if (containsAlphabetOrPad(lineSeparator)) {
                 final String sep = StringUtils.newStringUtf8(lineSeparator);
                 throw new IllegalArgumentException("lineSeparator must not contain Base32 characters: [" + sep + "]");
             }
             this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
             this.lineSeparator = new byte[lineSeparator.length];
             System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
         } else {
             this.encodeSize = BYTES_PER_ENCODED_BLOCK;
             this.lineSeparator = null;
         }
         this.decodeSize = this.encodeSize - 1;
     }
 
     /**
      * <p>
      * 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.
      * </p>
      * <p>
      * Ignores all non-Base32 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.
      * </p>
      *
      * @param in
      *            byte[] array of ascii data to Base32 decode.
      * @param inPos
      *            Position to start reading data from.
      * @param inAvail
      *            Amount of bytes available from input for encoding.
      * @param context the context to be used
      *
      * Output is written to {@link Context#buffer} as 8-bit octets, using {@link Context#pos} as the buffer position
      */
     @Override
     void decode(final byte[] in, int inPos, final int inAvail, final Context context) {
         // package protected for access from I/O streams
 
         if (context.eof) {
             return;
         }
         if (inAvail < 0) {
             context.eof = true;
         }
         for (int i = 0; i < inAvail; i++) {
             final byte b = in[inPos++];
             if (b == PAD) {
                 // We're done.
                 context.eof = true;
                 break;
             } else {
                 final byte[] buffer = ensureBufferSize(decodeSize, context);
                 if (b >= 0 && b < this.decodeTable.length) {
                     final int result = this.decodeTable[b];
                     if (result >= 0) {
                         context.modulus = (context.modulus+1) % BYTES_PER_ENCODED_BLOCK;
                         // collect decoded bytes
                         context.lbitWorkArea = (context.lbitWorkArea << BITS_PER_ENCODED_BYTE) + result;
                         if (context.modulus == 0) { // we can output the 5 bytes
                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 32) & MASK_8BITS);
                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 24) & MASK_8BITS);
                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
                             buffer[context.pos++] = (byte) (context.lbitWorkArea & MASK_8BITS);
                         }
                     }
                 }
             }
         }
 
         // Two forms of EOF as far as Base32 decoder is concerned: actual
         // EOF (-1) and first time '=' character is encountered in stream.
         // This approach makes the '=' padding characters completely optional.
         if (context.eof && context.modulus >= 2) { // if modulus < 2, nothing to do
             final byte[] buffer = ensureBufferSize(decodeSize, context);
 
             //  we ignore partial bytes, i.e. only multiples of 8 count
             switch (context.modulus) {
                 case 2 : // 10 bits, drop 2 and output one byte
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 2) & MASK_8BITS);
                     break;
                 case 3 : // 15 bits, drop 7 and output 1 byte
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 7) & MASK_8BITS);
                     break;
                 case 4 : // 20 bits = 2*8 + 4
                     context.lbitWorkArea = context.lbitWorkArea >> 4; // drop 4 bits
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
                     break;
                 case 5 : // 25bits = 3*8 + 1
                     context.lbitWorkArea = context.lbitWorkArea >> 1;
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
                     break;
                 case 6 : // 30bits = 3*8 + 6
                     context.lbitWorkArea = context.lbitWorkArea >> 6;
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
                     break;
                 case 7 : // 35 = 4*8 +3
                     context.lbitWorkArea = context.lbitWorkArea >> 3;
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 24) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
                     break;
                 default:
                     // modulus can be 0-7, and we excluded 0,1 already
                     throw new IllegalStateException("Impossible modulus "+context.modulus);
             }
         }
     }
 
     /**
      * <p>
      * 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 5).
      * </p>
      *
      * @param in
      *            byte[] array of binary data to Base32 encode.
      * @param inPos
      *            Position to start reading data from.
      * @param inAvail
      *            Amount of bytes available from input for encoding.
      * @param context the context to be used
      */
     @Override
     void encode(final byte[] in, int inPos, final int inAvail, final Context context) {
         // package protected for access from I/O streams
 
         if (context.eof) {
             return;
         }
         // inAvail < 0 is how we're informed of EOF in the underlying data we're
         // encoding.
         if (inAvail < 0) {
             context.eof = true;
             if (0 == context.modulus && lineLength == 0) {
                 return; // no leftovers to process and not using chunking
             }
             final byte[] buffer = ensureBufferSize(encodeSize, context);
             final int savedPos = context.pos;
             switch (context.modulus) { // % 5
                 case 0 :
                     break;
                 case 1 : // Only 1 octet; take top 5 bits then remainder
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 3) & MASK_5BITS]; // 8-1*5 = 3
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea << 2) & MASK_5BITS]; // 5-3=2
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     break;
                 case 2 : // 2 octets = 16 bits to use
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 11) & MASK_5BITS]; // 16-1*5 = 11
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  6) & MASK_5BITS]; // 16-2*5 = 6
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  1) & MASK_5BITS]; // 16-3*5 = 1
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea <<  4) & MASK_5BITS]; // 5-1 = 4
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     break;
                 case 3 : // 3 octets = 24 bits to use
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 19) & MASK_5BITS]; // 24-1*5 = 19
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 14) & MASK_5BITS]; // 24-2*5 = 14
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  9) & MASK_5BITS]; // 24-3*5 = 9
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  4) & MASK_5BITS]; // 24-4*5 = 4
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea <<  1) & MASK_5BITS]; // 5-4 = 1
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     buffer[context.pos++] = PAD;
                     break;
                 case 4 : // 4 octets = 32 bits to use
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 27) & MASK_5BITS]; // 32-1*5 = 27
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 22) & MASK_5BITS]; // 32-2*5 = 22
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 17) & MASK_5BITS]; // 32-3*5 = 17
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 12) & MASK_5BITS]; // 32-4*5 = 12
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  7) & MASK_5BITS]; // 32-5*5 =  7
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  2) & MASK_5BITS]; // 32-6*5 =  2
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea <<  3) & MASK_5BITS]; // 5-2 = 3
                     buffer[context.pos++] = PAD;
                     break;
                 default:
                     throw new IllegalStateException("Impossible modulus "+context.modulus);
             }
             context.currentLinePos += context.pos - savedPos; // keep track of current line position
             // if currentPos == 0 we are at the start of a line, so don't add CRLF
             if (lineLength > 0 && context.currentLinePos > 0){ // add chunk separator if required
                 System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
                 context.pos += lineSeparator.length;
             }
         } else {
             for (int i = 0; i < inAvail; i++) {
                 final byte[] buffer = ensureBufferSize(encodeSize, context);
                 context.modulus = (context.modulus+1) % BYTES_PER_UNENCODED_BLOCK;
                 int b = in[inPos++];
                 if (b < 0) {
                     b += 256;
                 }
                 context.lbitWorkArea = (context.lbitWorkArea << 8) + b; // BITS_PER_BYTE
                 if (0 == context.modulus) { // we have enough bytes to create our output
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 35) & MASK_5BITS];
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 30) & MASK_5BITS];
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 25) & MASK_5BITS];
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 20) & MASK_5BITS];
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 15) & MASK_5BITS];
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 10) & MASK_5BITS];
                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 5) & MASK_5BITS];
                     buffer[context.pos++] = encodeTable[(int)context.lbitWorkArea & MASK_5BITS];
                     context.currentLinePos += BYTES_PER_ENCODED_BLOCK;
                     if (lineLength > 0 && lineLength <= context.currentLinePos) {
                         System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
                         context.pos += lineSeparator.length;
                         context.currentLinePos = 0;
                     }
                 }
             }
         }
     }
 
     /**
      * Returns whether or not the <code>octet</code> is in the Base32 alphabet.
      *
      * @param octet
      *            The value to test
      * @return {@code true} if the value is defined in the the Base32 alphabet {@code false} otherwise.
      */
     @Override
     public boolean isInAlphabet(final byte octet) {
         return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
     }
 }