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[#1958] Use CRC32-C in Snappy as per the spec

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Luke Wood 2013-11-01 17:19:26 +00:00 committed by Norman Maurer
parent 16d32ed33a
commit 31c1513229
5 changed files with 147 additions and 21 deletions
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126
codec/src/main/java/io/netty/handler/codec/compression/Crc32c.java Normal file
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@ -0,0 +1,126 @@
/*
* Copyright 2013 The Netty Project
*
* The Netty Project 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 io.netty.handler.codec.compression;
import java.util.zip.Checksum;
/**
* Implements CRC32-C as defined in:
* "Optimization of Cyclic Redundancy-CHeck Codes with 24 and 32 Parity Bits",
* IEEE Transactions on Communications 41(6): 883-892 (1993).
*
* The implementation of this class has been sourced from the Appendix of RFC 3309,
* but with masking due to Java not being able to support unsigned types.
*/
class Crc32c implements Checksum {
private static final int[] CRC_TABLE = {
0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4,
0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B,
0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B,
0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54,
0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A,
0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5,
0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45,
0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A,
0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48,
0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687,
0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927,
0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8,
0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096,
0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859,
0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9,
0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36,
0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C,
0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043,
0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3,
0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C,
0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652,
0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D,
0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D,
0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2,
0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530,
0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF,
0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F,
0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90,
0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE,
0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321,
0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81,
0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E,
0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351,
};
private static final int LONG_MASK = 0xFFFFFFFF;
private static final int BYTE_MASK = 0xFF;
private int crc = ~0;
@Override
public void update(int b) {
crc = crc32c(crc, b);
}
@Override
public void update(byte[] buffer, int offset, int length) {
for (int i = offset; i < offset + length; i++) {
crc = crc32c(crc, buffer[i]);
}
}
@Override
public long getValue() {
return (crc ^ LONG_MASK) & LONG_MASK;
}
@Override
public void reset() {
crc = ~0;
}
private static int crc32c(int crc, int b) {
return (crc >>> 8) ^ CRC_TABLE[(crc ^ (b & BYTE_MASK)) & BYTE_MASK];
}
}

22
codec/src/main/java/io/netty/handler/codec/compression/Snappy.java
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@ -18,8 +18,6 @@ package io.netty.handler.codec.compression;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import java.util.zip.CRC32;
/**
* Uncompresses an input {@link ByteBuf} encoded with Snappy compression into an
* output {@link ByteBuf}.
@ -597,30 +595,30 @@ public class Snappy {
}
/**
* Computes the CRC32 checksum of the supplied data and performs the "mask" operation
* Computes the CRC32C checksum of the supplied data and performs the "mask" operation
* on the computed checksum
*
* @param data The input data to calculate the CRC32 checksum of
* @param data The input data to calculate the CRC32C checksum of
*/
public static int calculateChecksum(ByteBuf data) {
return calculateChecksum(data, data.readerIndex(), data.readableBytes());
}
/**
* Computes the CRC32 checksum of the supplied data and performs the "mask" operation
* Computes the CRC32C checksum of the supplied data and performs the "mask" operation
* on the computed checksum
*
* @param data The input data to calculate the CRC32 checksum of
* @param data The input data to calculate the CRC32C checksum of
*/
public static int calculateChecksum(ByteBuf data, int offset, int length) {
CRC32 crc32 = new CRC32();
Crc32c crc32 = new Crc32c();
try {
if (data.hasArray()) {
crc32.update(data.array(), data.arrayOffset() + offset, length);
} else {
byte[] array = new byte[length];
data.getBytes(offset, array);
crc32.update(array);
crc32.update(array, 0, length);
}
return maskChecksum((int) crc32.getValue());
@ -630,12 +628,12 @@ public class Snappy {
}
/**
* Computes the CRC32 checksum of the supplied data, performs the "mask" operation
* Computes the CRC32C checksum of the supplied data, performs the "mask" operation
* on the computed checksum, and then compares the resulting masked checksum to the
* supplied checksum.
*
* @param expectedChecksum The checksum decoded from the stream to compare against
* @param data The input data to calculate the CRC32 checksum of
* @param data The input data to calculate the CRC32C checksum of
* @throws DecompressionException If the calculated and supplied checksums do not match
*/
static void validateChecksum(int expectedChecksum, ByteBuf data) {
@ -643,12 +641,12 @@ public class Snappy {
}
/**
* Computes the CRC32 checksum of the supplied data, performs the "mask" operation
* Computes the CRC32C checksum of the supplied data, performs the "mask" operation
* on the computed checksum, and then compares the resulting masked checksum to the
* supplied checksum.
*
* @param expectedChecksum The checksum decoded from the stream to compare against
* @param data The input data to calculate the CRC32 checksum of
* @param data The input data to calculate the CRC32C checksum of
* @throws DecompressionException If the calculated and supplied checksums do not match
*/
static void validateChecksum(int expectedChecksum, ByteBuf data, int offset, int length) {

4
codec/src/test/java/io/netty/handler/codec/compression/SnappyFramedDecoderTest.java
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@ -147,10 +147,10 @@ public class SnappyFramedDecoderTest {
public void testInvalidChecksumDoesNotThrowException() throws Exception {
EmbeddedChannel channel = new EmbeddedChannel(new SnappyFramedDecoder(true));
// checksum here is presented as -1568496083 (little endian)
// checksum here is presented as a282986f (little endian)
ByteBuf in = Unpooled.wrappedBuffer(new byte[] {
-0x80, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59,
0x01, 0x09, 0x00, 0x00, 0x2d, -0x5a, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y'
0x01, 0x09, 0x00, 0x00, 0x6f, -0x68, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y'
});
channel.writeInbound(in);

10
codec/src/test/java/io/netty/handler/codec/compression/SnappyFramedEncoderTest.java
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@ -43,8 +43,9 @@ public class SnappyFramedEncoderTest {
ByteBuf expected = Unpooled.wrappedBuffer(new byte[] {
-0x80, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59,
0x01, 0x09, 0x00, 0x00, 0x2d, -0x5a, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y'
0x01, 0x09, 0x00, 0x00, 0x6f, -0x68, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y'
});
assertEquals(expected, channel.readOutbound());
}
@ -60,11 +61,12 @@ public class SnappyFramedEncoderTest {
ByteBuf expected = Unpooled.wrappedBuffer(new byte[] {
-0x80, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59,
0x00, 0x0E, 0x00, 0x00, 0x7b, 0x1f, 0x65, 0x64,
0x00, 0x0E, 0x00, 0x00, 0x3b, 0x36, -0x7f, 0x37,
0x14, 0x10,
'n', 'e', 't', 't', 'y',
0x3a, 0x05, 0x00
});
assertEquals(expected, channel.readOutbound());
}
@ -81,8 +83,8 @@ public class SnappyFramedEncoderTest {
ByteBuf expected = Unpooled.wrappedBuffer(new byte[] {
-0x80, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59,
0x01, 0x09, 0x00, 0x00, 0x2d, -0x5a, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y',
0x01, 0x09, 0x00, 0x00, 0x2d, -0x5a, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y',
0x01, 0x09, 0x00, 0x00, 0x6f, -0x68, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y',
0x01, 0x09, 0x00, 0x00, 0x6f, -0x68, -0x7e, -0x5e, 'n', 'e', 't', 't', 'y',
});
CompositeByteBuf actual = Unpooled.compositeBuffer();

6
codec/src/test/java/io/netty/handler/codec/compression/SnappyTest.java
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@ -175,7 +175,7 @@ public class SnappyTest {
ByteBuf input = Unpooled.wrappedBuffer(new byte[] {
'n', 'e', 't', 't', 'y'
});
assertEquals(maskChecksum(0xddaa8ce6), calculateChecksum(input));
assertEquals(maskChecksum(0xd6cb8b55), calculateChecksum(input));
}
@Test
@ -184,7 +184,7 @@ public class SnappyTest {
'y', 't', 't', 'e', 'n'
});
validateChecksum(maskChecksum(0x37c55159), input);
validateChecksum(maskChecksum(0x2d4d3535), input);
}
@Test(expected = DecompressionException.class)
@ -193,6 +193,6 @@ public class SnappyTest {
'y', 't', 't', 'e', 'n'
});
validateChecksum(maskChecksum(0xddaa8ce6), input);
validateChecksum(maskChecksum(0xd6cb8b55), input);
}
}