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Patch for CODEC-239 - Allow "look-alike" characters when decoding Base32 #26

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Patch for CODEC-239 - Allow "look-alike" characters when decoding Base32 #26

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131 changes: 129 additions & 2 deletions src/main/java/org/apache/commons/codec/binary/Base32.java
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,25 @@ public class Base32 extends BaseNCodec {
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 70 - 7a p-z/**/
};

/**
* This array is a lookup table that translates Unicode characters drawn from the "Base32 Alphabet" (as specified
* in Table 3 of RFC 4648) 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.
* Look-alike characters are 0 (zero) and 1 (one).
*/
private static final byte[] DECODE_TABLE_WITH_LOOKALIKES = {
// 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, -1, // 20-2f
14, 8, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, // 30-3f 0-7
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 40-4f A-O
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 50-5a P-Z
-1, -1, -1, -1, -1, // 5b - 5f [-_
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 60 - 6f `-o
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 70 - 7a p-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 4648.
Expand Down Expand Up @@ -104,6 +123,24 @@ public class Base32 extends BaseNCodec {
25, 26, 27, 28, 29, 30, 31 // 70-76 p-v
};

/**
* This array is a lookup table that translates Unicode characters drawn from the "Base32 Hex Alphabet" (as
* specified in Table 4 of RFC 4648) 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_WITH_LOOKALIKES = {
// 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, -1, // 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-O
25, 26, 27, 28, 29, 30, 31, // 50-57 P-V
-1, -1, -1, -1, -1, -1, -1, -1, -1, // 57-5f W-_
-1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 60-6f `-o
25, 26, 27, 28, 29, 30, 31 // 70-76 p-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 4 of RFC 4648.
Expand Down Expand Up @@ -186,6 +223,20 @@ public Base32(final boolean useHex) {
this(0, null, useHex, PAD_DEFAULT);
}

/**
* 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
* @param allowLookalikes
* if {@code true}, then allow look-alike characters like {@code 0} -&gt; {@code O}
* and {@code 1} -&gt; {@code O} when decoding, otherwise ignore look-alike characters
*/
public Base32(final boolean useHex, final boolean allowLookalikes) {
this(0, null, useHex, allowLookalikes, PAD_DEFAULT);
}

/**
* Creates a Base32 codec used for decoding and encoding.
* <p>
Expand All @@ -198,6 +249,22 @@ public Base32(final boolean useHex, final byte pad) {
this(0, null, useHex, pad);
}


/**
* 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
* @param allowLookalikes
* if {@code true}, then allow look-alike characters like {@code 0} -&gt; {@code O}
* and {@code 1} -&gt; {@code O} when decoding, otherwise ignore look-alike characters
* @param pad byte used as padding byte.
*/
public Base32(final boolean useHex, final boolean allowLookalikes, final byte pad) {
this(0, null, useHex, allowLookalikes, pad);
}

/**
* Creates a Base32 codec used for decoding and encoding.
* <p>
Expand Down Expand Up @@ -260,6 +327,31 @@ public Base32(final int lineLength, final byte[] lineSeparator, final boolean us
this(lineLength, lineSeparator, useHex, PAD_DEFAULT);
}

/**
* 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 &lt;= 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 &gt; 0 and lineSeparator is null.
*/
public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex, final boolean allowLookalikes) {
this(lineLength, lineSeparator, useHex, allowLookalikes, PAD_DEFAULT);
}

/**
* Creates a Base32 / Base32 Hex codec used for decoding and encoding.
* <p>
Expand All @@ -283,14 +375,49 @@ public Base32(final int lineLength, final byte[] lineSeparator, final boolean us
* lineLength &gt; 0 and lineSeparator is null.
*/
public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex, final byte pad) {
this(lineLength, lineSeparator, useHex, false, pad);
}

/**
* 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 &lt;= 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
* @param allowLookalikes
* if {@code true}, then allow look-alike characters like {@code 0} -&gt; {@code O}
* and {@code 1} -&gt; {@code O} when decoding, otherwise ignore-alike characters.
* @param pad byte used as padding byte.
* @throws IllegalArgumentException
* The provided lineSeparator included some Base32 characters. That's not going to work! Or the
* lineLength &gt; 0 and lineSeparator is null.
*/
public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex, final boolean allowLookalikes, final byte pad) {
super(BYTES_PER_UNENCODED_BLOCK, BYTES_PER_ENCODED_BLOCK, lineLength,
lineSeparator == null ? 0 : lineSeparator.length, pad);
if (useHex) {
this.encodeTable = HEX_ENCODE_TABLE;
this.decodeTable = HEX_DECODE_TABLE;
if(allowLookalikes)
this.decodeTable = HEX_DECODE_TABLE_WITH_LOOKALIKES;
else
this.decodeTable = HEX_DECODE_TABLE;
} else {
this.encodeTable = ENCODE_TABLE;
this.decodeTable = DECODE_TABLE;
if(allowLookalikes)
this.decodeTable = DECODE_TABLE_WITH_LOOKALIKES;
else
this.decodeTable = DECODE_TABLE;
}
if (lineLength > 0) {
if (lineSeparator == null) {
Expand Down
25 changes: 24 additions & 1 deletion src/test/java/org/apache/commons/codec/binary/Base32Test.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,8 @@

package org.apache.commons.codec.binary;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.fail;

Expand Down Expand Up @@ -120,6 +120,14 @@ public class Base32Test {
{"foobar" ,"MZXW6YTBOI%%%%%%"},
};

private static final String[][] BASE32_LOOKALIKES = {
{ "O0oOI1iI", "OOOOIIII" }
};

private static final String[][] BASE32_HEX_LOOKALIKES = {
{ "O0oOI1iI", "OOOOIIII" }
};

@Test
public void testBase64AtBufferStart() {
testBase64InBuffer(0, 100);
Expand Down Expand Up @@ -297,4 +305,19 @@ private void testImpossibleCases(final Base32 codec, final String[] impossible_c
}
}
}
@Test
public void testBase32Lookalikes() throws Exception {
final Base32 codec = new Base32(false, true);
for(String[] element : BASE32_LOOKALIKES)
assertArrayEquals(codec.decode(element[0]),
codec.decode(element[1]));
}

@Test
public void testBase32HexLookalikes() throws Exception {
final Base32 codec = new Base32(false, true);
for(String[] element : BASE32_HEX_LOOKALIKES)
assertArrayEquals(codec.decode(element[0]),
codec.decode(element[1]));
}
}