692 lines
23 KiB
Java
692 lines
23 KiB
Java
package net.lax1dude.eaglercraft.v1_8;
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import java.nio.charset.Charset;
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import java.util.Arrays;
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public abstract class BaseNCodec {
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static enum CodecPolicy {
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STRICT, LENIANT;
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}
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/**
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* Holds thread context so classes can be thread-safe.
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*
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* This class is not itself thread-safe; each thread must allocate its own copy.
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*
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* @since 1.7
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*/
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static class Context {
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/**
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* Place holder for the bytes we're dealing with for our based logic. Bitwise
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* operations store and extract the encoding or decoding from this variable.
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*/
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int ibitWorkArea;
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/**
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* Place holder for the bytes we're dealing with for our based logic. Bitwise
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* operations store and extract the encoding or decoding from this variable.
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*/
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long lbitWorkArea;
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/**
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* Buffer for streaming.
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*/
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byte[] buffer;
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/**
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* Position where next character should be written in the buffer.
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*/
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int pos;
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/**
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* Position where next character should be read from the buffer.
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*/
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int readPos;
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/**
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* Boolean flag to indicate the EOF has been reached. Once EOF has been reached,
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* this object becomes useless, and must be thrown away.
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*/
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boolean eof;
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/**
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* Variable tracks how many characters have been written to the current line.
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* Only used when encoding. We use it to make sure each encoded line never goes
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* beyond lineLength (if lineLength > 0).
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*/
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int currentLinePos;
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/**
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* Writes to the buffer only occur after every 3/5 reads when encoding, and
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* every 4/8 reads when decoding. This variable helps track that.
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*/
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int modulus;
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Context() {
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}
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/**
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* Returns a String useful for debugging (especially within a debugger.)
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*
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* @return a String useful for debugging.
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*/
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@SuppressWarnings("boxing") // OK to ignore boxing here
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@Override
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public String toString() {
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return HString.format(
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"%s[buffer=%s, currentLinePos=%s, eof=%s, ibitWorkArea=%s, lbitWorkArea=%s, "
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+ "modulus=%s, pos=%s, readPos=%s]",
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this.getClass().getSimpleName(), Arrays.toString(buffer), currentLinePos, eof, ibitWorkArea,
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lbitWorkArea, modulus, pos, readPos);
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}
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}
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/**
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* EOF
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*
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* @since 1.7
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*/
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static final int EOF = -1;
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/**
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* MIME chunk size per RFC 2045 section 6.8.
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*
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* <p>
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* The {@value} character limit does not count the trailing CRLF, but counts all
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* other characters, including any equal signs.
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* </p>
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*
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* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
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*/
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public static final int MIME_CHUNK_SIZE = 76;
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/**
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* PEM chunk size per RFC 1421 section 4.3.2.4.
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*
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* <p>
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* The {@value} character limit does not count the trailing CRLF, but counts all
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* other characters, including any equal signs.
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* </p>
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*
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* @see <a href="http://tools.ietf.org/html/rfc1421">RFC 1421 section
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* 4.3.2.4</a>
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*/
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public static final int PEM_CHUNK_SIZE = 64;
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private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
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/**
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* Defines the default buffer size - currently {@value} - must be large enough
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* for at least one encoded block+separator
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*/
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private static final int DEFAULT_BUFFER_SIZE = 8192;
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/**
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* The maximum size buffer to allocate.
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*
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* <p>
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* This is set to the same size used in the JDK {@code java.util.ArrayList}:
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* </p>
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* <blockquote> Some VMs reserve some header words in an array. Attempts to
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* allocate larger arrays may result in OutOfMemoryError: Requested array size
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* exceeds VM limit. </blockquote>
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*/
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private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8;
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/** Mask used to extract 8 bits, used in decoding bytes */
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protected static final int MASK_8BITS = 0xff;
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/**
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* Byte used to pad output.
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*/
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protected static final byte PAD_DEFAULT = '='; // Allow static access to default
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/**
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* Chunk separator per RFC 2045 section 2.1.
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*
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* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
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*/
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static final byte[] CHUNK_SEPARATOR = { '\r', '\n' };
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/**
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* Compares two {@code int} values numerically treating the values as unsigned.
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* Taken from JDK 1.8.
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*
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* <p>
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* TODO: Replace with JDK 1.8 Integer::compareUnsigned(int, int).
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* </p>
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*
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* @param x the first {@code int} to compare
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* @param y the second {@code int} to compare
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* @return the value {@code 0} if {@code x == y}; a value less than {@code 0} if
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* {@code x < y} as unsigned values; and a value greater than {@code 0}
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* if {@code x > y} as unsigned values
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*/
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private static int compareUnsigned(final int xx, final int yy) {
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int x = xx + Integer.MIN_VALUE;
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int y = yy + Integer.MIN_VALUE;
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return (x < y) ? -1 : ((x == y) ? 0 : 1);
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}
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/**
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* Create a positive capacity at least as large the minimum required capacity.
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* If the minimum capacity is negative then this throws an OutOfMemoryError as
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* no array can be allocated.
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*
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* @param minCapacity the minimum capacity
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* @return the capacity
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* @throws OutOfMemoryError if the {@code minCapacity} is negative
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*/
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private static int createPositiveCapacity(final int minCapacity) {
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if (minCapacity < 0) {
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// overflow
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throw new OutOfMemoryError("Unable to allocate array size: " + (minCapacity & 0xffffffffL));
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}
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// This is called when we require buffer expansion to a very big array.
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// Use the conservative maximum buffer size if possible, otherwise the biggest
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// required.
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//
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// Note: In this situation JDK 1.8 java.util.ArrayList returns
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// Integer.MAX_VALUE.
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// This excludes some VMs that can exceed MAX_BUFFER_SIZE but not allocate a
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// full
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// Integer.MAX_VALUE length array.
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// The result is that we may have to allocate an array of this size more than
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// once if
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// the capacity must be expanded again.
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return (minCapacity > MAX_BUFFER_SIZE) ? minCapacity : MAX_BUFFER_SIZE;
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}
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/**
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* Gets a copy of the chunk separator per RFC 2045 section 2.1.
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*
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* @return the chunk separator
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* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
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* @since 1.15
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*/
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public static byte[] getChunkSeparator() {
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return CHUNK_SEPARATOR.clone();
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}
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/**
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* Checks if a byte value is whitespace or not. Whitespace is taken to mean:
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* space, tab, CR, LF
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*
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* @param byteToCheck the byte to check
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* @return true if byte is whitespace, false otherwise
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*/
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protected static boolean isWhiteSpace(final byte byteToCheck) {
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switch (byteToCheck) {
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case ' ':
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case '\n':
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case '\r':
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case '\t':
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return true;
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default:
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return false;
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}
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}
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/**
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* Increases our buffer by the {@link #DEFAULT_BUFFER_RESIZE_FACTOR}.
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*
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* @param context the context to be used
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* @param minCapacity the minimum required capacity
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* @return the resized byte[] buffer
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* @throws OutOfMemoryError if the {@code minCapacity} is negative
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*/
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private static byte[] resizeBuffer(final Context context, final int minCapacity) {
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// Overflow-conscious code treats the min and new capacity as unsigned.
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final int oldCapacity = context.buffer.length;
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int newCapacity = oldCapacity * DEFAULT_BUFFER_RESIZE_FACTOR;
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if (compareUnsigned(newCapacity, minCapacity) < 0) {
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newCapacity = minCapacity;
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}
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if (compareUnsigned(newCapacity, MAX_BUFFER_SIZE) > 0) {
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newCapacity = createPositiveCapacity(minCapacity);
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}
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final byte[] b = new byte[newCapacity];
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System.arraycopy(context.buffer, 0, b, 0, context.buffer.length);
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context.buffer = b;
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return b;
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}
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/**
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* @deprecated Use {@link #pad}. Will be removed in 2.0.
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*/
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@Deprecated
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protected final byte PAD = PAD_DEFAULT; // instance variable just in case it needs to vary later
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protected final byte pad; // instance variable just in case it needs to vary later
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/**
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* Number of bytes in each full block of unencoded data, e.g. 4 for Base64 and 5
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* for Base32
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*/
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private final int unencodedBlockSize;
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/**
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* Number of bytes in each full block of encoded data, e.g. 3 for Base64 and 8
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* for Base32
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*/
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private final int encodedBlockSize;
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/**
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* Chunksize for encoding. Not used when decoding. A value of zero or less
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* implies no chunking of the encoded data. Rounded down to nearest multiple of
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* encodedBlockSize.
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*/
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protected final int lineLength;
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/**
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* Size of chunk separator. Not used unless {@link #lineLength} > 0.
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*/
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private final int chunkSeparatorLength;
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/**
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* Defines the decoding behavior when the input bytes contain leftover trailing
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* bits that cannot be created by a valid encoding. These can be bits that are
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* unused from the final character or entire characters. The default mode is
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* lenient decoding. Set this to {@code true} to enable strict decoding.
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* <ul>
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* <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible.
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* The remainder are discarded.
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* <li>Strict: The decoding will raise an {@link IllegalArgumentException} if
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* trailing bits are not part of a valid encoding. Any unused bits from the
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* final character must be zero. Impossible counts of entire final characters
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* are not allowed.
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* </ul>
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*
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* <p>
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* When strict decoding is enabled it is expected that the decoded bytes will be
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* re-encoded to a byte array that matches the original, i.e. no changes occur
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* on the final character. This requires that the input bytes use the same
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* padding and alphabet as the encoder.
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*/
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private final CodecPolicy decodingPolicy;
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/**
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* Note {@code lineLength} is rounded down to the nearest multiple of the
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* encoded block size. If {@code chunkSeparatorLength} is zero, then chunking is
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* disabled.
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*
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* @param unencodedBlockSize the size of an unencoded block (e.g. Base64 = 3)
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* @param encodedBlockSize the size of an encoded block (e.g. Base64 = 4)
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* @param lineLength if > 0, use chunking with a length
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* {@code lineLength}
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* @param chunkSeparatorLength the chunk separator length, if relevant
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*/
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protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength,
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final int chunkSeparatorLength) {
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this(unencodedBlockSize, encodedBlockSize, lineLength, chunkSeparatorLength, PAD_DEFAULT);
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}
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/**
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* Note {@code lineLength} is rounded down to the nearest multiple of the
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* encoded block size. If {@code chunkSeparatorLength} is zero, then chunking is
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* disabled.
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*
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* @param unencodedBlockSize the size of an unencoded block (e.g. Base64 = 3)
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* @param encodedBlockSize the size of an encoded block (e.g. Base64 = 4)
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* @param lineLength if > 0, use chunking with a length
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* {@code lineLength}
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* @param chunkSeparatorLength the chunk separator length, if relevant
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* @param pad byte used as padding byte.
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*/
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protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength,
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final int chunkSeparatorLength, final byte pad) {
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this(unencodedBlockSize, encodedBlockSize, lineLength, chunkSeparatorLength, pad, CodecPolicy.LENIANT);
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}
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/**
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* Note {@code lineLength} is rounded down to the nearest multiple of the
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* encoded block size. If {@code chunkSeparatorLength} is zero, then chunking is
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* disabled.
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*
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* @param unencodedBlockSize the size of an unencoded block (e.g. Base64 = 3)
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* @param encodedBlockSize the size of an encoded block (e.g. Base64 = 4)
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* @param lineLength if > 0, use chunking with a length
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* {@code lineLength}
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* @param chunkSeparatorLength the chunk separator length, if relevant
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* @param pad byte used as padding byte.
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* @param decodingPolicy Decoding policy.
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* @since 1.15
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*/
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protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength,
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final int chunkSeparatorLength, final byte pad, final CodecPolicy decodingPolicy) {
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this.unencodedBlockSize = unencodedBlockSize;
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this.encodedBlockSize = encodedBlockSize;
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final boolean useChunking = lineLength > 0 && chunkSeparatorLength > 0;
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this.lineLength = useChunking ? (lineLength / encodedBlockSize) * encodedBlockSize : 0;
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this.chunkSeparatorLength = chunkSeparatorLength;
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this.pad = pad;
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this.decodingPolicy = decodingPolicy;
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}
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/**
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* Returns the amount of buffered data available for reading.
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*
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* @param context the context to be used
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* @return The amount of buffered data available for reading.
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*/
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int available(final Context context) { // package protected for access from I/O streams
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return context.buffer != null ? context.pos - context.readPos : 0;
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}
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/**
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* Tests a given byte array to see if it contains any characters within the
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* alphabet or PAD.
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*
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* Intended for use in checking line-ending arrays
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*
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* @param arrayOctet byte array to test
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* @return {@code true} if any byte is a valid character in the alphabet or PAD;
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* {@code false} otherwise
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*/
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protected boolean containsAlphabetOrPad(final byte[] arrayOctet) {
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if (arrayOctet == null) {
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return false;
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}
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for (final byte element : arrayOctet) {
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if (pad == element || isInAlphabet(element)) {
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return true;
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}
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}
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return false;
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}
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/**
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* Decodes a byte[] containing characters in the Base-N alphabet.
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*
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* @param pArray A byte array containing Base-N character data
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* @return a byte array containing binary data
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*/
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public byte[] decode(final byte[] pArray) {
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if (pArray == null || pArray.length == 0) {
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return pArray;
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}
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final Context context = new Context();
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decode(pArray, 0, pArray.length, context);
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decode(pArray, 0, EOF, context); // Notify decoder of EOF.
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final byte[] result = new byte[context.pos];
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readResults(result, 0, result.length, context);
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return result;
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}
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// package protected for access from I/O streams
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abstract void decode(byte[] pArray, int i, int length, Context context);
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/**
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* Decodes an Object using the Base-N algorithm. This method is provided in
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* order to satisfy the requirements of the Decoder interface, and will throw a
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* DecoderException if the supplied object is not of type byte[] or String.
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*
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* @param obj Object to decode
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* @return An object (of type byte[]) containing the binary data which
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* corresponds to the byte[] or String supplied.
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* @throws DecoderException if the parameter supplied is not of type byte[]
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*/
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public Object decode(final Object obj) {
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if (obj instanceof byte[]) {
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return decode((byte[]) obj);
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} else if (obj instanceof String) {
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return decode((String) obj);
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} else {
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return null;
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}
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}
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/**
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* Decodes a String containing characters in the Base-N alphabet.
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*
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* @param pArray A String containing Base-N character data
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* @return a byte array containing binary data
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*/
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public byte[] decode(final String pArray) {
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return decode(pArray.getBytes(Charset.forName("UTF-8")));
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}
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/**
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* Encodes a byte[] containing binary data, into a byte[] containing characters
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* in the alphabet.
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*
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* @param pArray a byte array containing binary data
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* @return A byte array containing only the base N alphabetic character data
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*/
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public byte[] encode(final byte[] pArray) {
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if (pArray == null || pArray.length == 0) {
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return pArray;
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}
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return encode(pArray, 0, pArray.length);
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}
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/**
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* Encodes a byte[] containing binary data, into a byte[] containing characters
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* in the alphabet.
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*
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* @param pArray a byte array containing binary data
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* @param offset initial offset of the subarray.
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* @param length length of the subarray.
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* @return A byte array containing only the base N alphabetic character data
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* @since 1.11
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*/
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public byte[] encode(final byte[] pArray, final int offset, final int length) {
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if (pArray == null || pArray.length == 0) {
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return pArray;
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}
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final Context context = new Context();
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encode(pArray, offset, length, context);
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encode(pArray, offset, EOF, context); // Notify encoder of EOF.
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final byte[] buf = new byte[context.pos - context.readPos];
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readResults(buf, 0, buf.length, context);
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return buf;
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}
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// package protected for access from I/O streams
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abstract void encode(byte[] pArray, int i, int length, Context context);
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/**
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* Encodes an Object using the Base-N algorithm. This method is provided in
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* order to satisfy the requirements of the Encoder interface, and will throw an
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* EncoderException if the supplied object is not of type byte[].
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*
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* @param obj Object to encode
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* @return An object (of type byte[]) containing the Base-N encoded data which
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* corresponds to the byte[] supplied.
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* @throws EncoderException if the parameter supplied is not of type byte[]
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*/
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public Object encode(final Object obj) {
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return encode((byte[]) obj);
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}
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/**
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* Encodes a byte[] containing binary data, into a String containing characters
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* in the appropriate alphabet. Uses UTF8 encoding.
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*
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* @param pArray a byte array containing binary data
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* @return String containing only character data in the appropriate alphabet.
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* @since 1.5 This is a duplicate of {@link #encodeToString(byte[])}; it was
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* merged during refactoring.
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*/
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public String encodeAsString(final byte[] pArray) {
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return new String(encode(pArray), Charset.forName("UTF-8"));
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}
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/**
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* Encodes a byte[] containing binary data, into a String containing characters
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* in the Base-N alphabet. Uses UTF8 encoding.
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*
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* @param pArray a byte array containing binary data
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* @return A String containing only Base-N character data
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*/
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public String encodeToString(final byte[] pArray) {
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return new String(encode(pArray), Charset.forName("UTF-8"));
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}
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/**
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* Ensure that the buffer has room for {@code size} bytes
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*
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* @param size minimum spare space required
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* @param context the context to be used
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* @return the buffer
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*/
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protected byte[] ensureBufferSize(final int size, final Context context) {
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if (context.buffer == null) {
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context.buffer = new byte[Math.max(size, getDefaultBufferSize())];
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context.pos = 0;
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context.readPos = 0;
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// Overflow-conscious:
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// x + y > z == x + y - z > 0
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} else if (context.pos + size - context.buffer.length > 0) {
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return resizeBuffer(context, context.pos + size);
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}
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return context.buffer;
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}
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/**
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* Returns the decoding behavior policy.
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*
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* <p>
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* The default is lenient. If the decoding policy is strict, then decoding will
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* raise an {@link IllegalArgumentException} if trailing bits are not part of a
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* valid encoding. Decoding will compose trailing bits into 8-bit bytes and
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* discard the remainder.
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* </p>
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*
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* @return true if using strict decoding
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* @since 1.15
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*/
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public CodecPolicy getCodecPolicy() {
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return decodingPolicy;
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}
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/**
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* Get the default buffer size. Can be overridden.
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*
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* @return the default buffer size.
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*/
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protected int getDefaultBufferSize() {
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return DEFAULT_BUFFER_SIZE;
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}
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/**
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* Calculates the amount of space needed to encode the supplied array.
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*
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* @param pArray byte[] array which will later be encoded
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*
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* @return amount of space needed to encoded the supplied array. Returns a long
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* since a max-len array will require > Integer.MAX_VALUE
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*/
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public long getEncodedLength(final byte[] pArray) {
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// Calculate non-chunked size - rounded up to allow for padding
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// cast to long is needed to avoid possibility of overflow
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long len = ((pArray.length + unencodedBlockSize - 1) / unencodedBlockSize) * (long) encodedBlockSize;
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if (lineLength > 0) { // We're using chunking
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// Round up to nearest multiple
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len += ((len + lineLength - 1) / lineLength) * chunkSeparatorLength;
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}
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return len;
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}
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/**
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* Returns true if this object has buffered data for reading.
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*
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* @param context the context to be used
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* @return true if there is data still available for reading.
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*/
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boolean hasData(final Context context) { // package protected for access from I/O streams
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return context.buffer != null;
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}
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/**
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* Returns whether or not the {@code octet} is in the current alphabet. Does not
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* allow whitespace or pad.
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*
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* @param value The value to test
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*
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* @return {@code true} if the value is defined in the current alphabet,
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* {@code false} otherwise.
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*/
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protected abstract boolean isInAlphabet(byte value);
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/**
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* Tests a given byte array to see if it contains only valid characters within
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* the alphabet. The method optionally treats whitespace and pad as valid.
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*
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* @param arrayOctet byte array to test
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* @param allowWSPad if {@code true}, then whitespace and PAD are also allowed
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*
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* @return {@code true} if all bytes are valid characters in the alphabet or if
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* the byte array is empty; {@code false}, otherwise
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|
*/
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|
public boolean isInAlphabet(final byte[] arrayOctet, final boolean allowWSPad) {
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for (final byte octet : arrayOctet) {
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if (!isInAlphabet(octet) && (!allowWSPad || (octet != pad) && !isWhiteSpace(octet))) {
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return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Tests a given String to see if it contains only valid characters within the
|
|
* alphabet. The method treats whitespace and PAD as valid.
|
|
*
|
|
* @param basen String to test
|
|
* @return {@code true} if all characters in the String are valid characters in
|
|
* the alphabet or if the String is empty; {@code false}, otherwise
|
|
* @see #isInAlphabet(byte[], boolean)
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|
*/
|
|
public boolean isInAlphabet(final String basen) {
|
|
return isInAlphabet(basen.getBytes(Charset.forName("UTF-8")), true);
|
|
}
|
|
|
|
/**
|
|
* Returns true if decoding behavior is strict. Decoding will raise an
|
|
* {@link IllegalArgumentException} if trailing bits are not part of a valid
|
|
* encoding.
|
|
*
|
|
* <p>
|
|
* The default is false for lenient decoding. Decoding will compose trailing
|
|
* bits into 8-bit bytes and discard the remainder.
|
|
* </p>
|
|
*
|
|
* @return true if using strict decoding
|
|
* @since 1.15
|
|
*/
|
|
public boolean isStrictDecoding() {
|
|
return decodingPolicy == CodecPolicy.STRICT;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
* <p>
|
|
* Package protected for access from I/O streams.
|
|
*
|
|
* @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).
|
|
* @param context the context to be used
|
|
* @return The number of bytes successfully extracted into the provided byte[]
|
|
* array.
|
|
*/
|
|
int readResults(final byte[] b, final int bPos, final int bAvail, final Context context) {
|
|
if (context.buffer != null) {
|
|
final int len = Math.min(available(context), bAvail);
|
|
System.arraycopy(context.buffer, context.readPos, b, bPos, len);
|
|
context.readPos += len;
|
|
if (context.readPos >= context.pos) {
|
|
context.buffer = null; // so hasData() will return false, and this method can return -1
|
|
}
|
|
return len;
|
|
}
|
|
return context.eof ? EOF : 0;
|
|
}
|
|
} |