Crypto++ 8.9
Free C++ class library of cryptographic schemes
zlib.cpp
1// zlib.cpp - originally written and placed in the public domain by Wei Dai
2
3// "zlib" is the name of a well known C language compression library
4// (http://www.zlib.org) and also the name of a compression format
5// (RFC 1950) that the library implements. This file is part of a
6// complete reimplementation of the zlib compression format.
7
8#include "pch.h"
9#include "zlib.h"
10#include "zdeflate.h"
11#include "zinflate.h"
12#include "secblock.h"
13
14NAMESPACE_BEGIN(CryptoPP)
15
16static const byte DEFLATE_METHOD = 8;
17static const byte FDICT_FLAG = (1 << 5);
18
19// *************************************************************
20
21void ZlibCompressor::WritePrestreamHeader()
22{
23 m_adler32.Restart();
24 CRYPTOPP_ASSERT(((GetLog2WindowSize()-8) << 4) <= 255);
25 byte cmf = byte(DEFLATE_METHOD | ((GetLog2WindowSize()-8) << 4));
26 CRYPTOPP_ASSERT((GetCompressionLevel() << 6) <= 255);
27 byte flags = byte(GetCompressionLevel() << 6);
29}
30
31void ZlibCompressor::ProcessUncompressedData(const byte *inString, size_t length)
32{
33 m_adler32.Update(inString, length);
34}
35
36void ZlibCompressor::WritePoststreamTail()
37{
39 m_adler32.Final(adler32);
40 AttachedTransformation()->Put(adler32, 4);
41}
42
43unsigned int ZlibCompressor::GetCompressionLevel() const
44{
45 static const unsigned int deflateToCompressionLevel[] = {0, 1, 1, 1, 2, 2, 2, 2, 2, 3};
46 return deflateToCompressionLevel[GetDeflateLevel()];
47}
48
49// *************************************************************
50
51ZlibDecompressor::ZlibDecompressor(BufferedTransformation *attachment, bool repeat, int propagation)
52 : Inflator(attachment, repeat, propagation), m_log2WindowSize(0)
53{
54}
55
56void ZlibDecompressor::ProcessPrestreamHeader()
57{
58 m_adler32.Restart();
59
60 byte cmf;
61 byte flags;
62
63 if (!m_inQueue.Get(cmf) || !m_inQueue.Get(flags))
64 throw HeaderErr();
65
66 if ((cmf*256+flags) % 31 != 0)
67 throw HeaderErr(); // if you hit this exception, you're probably trying to decompress invalid data
68
69 if ((cmf & 0xf) != DEFLATE_METHOD)
70 throw UnsupportedAlgorithm();
71
72 if (flags & FDICT_FLAG)
73 throw UnsupportedPresetDictionary();
74
75 m_log2WindowSize = 8 + (cmf >> 4);
76}
77
78void ZlibDecompressor::ProcessDecompressedData(const byte *inString, size_t length)
79{
80 AttachedTransformation()->Put(inString, length);
81 m_adler32.Update(inString, length);
82}
83
84void ZlibDecompressor::ProcessPoststreamTail()
85{
87 if (m_inQueue.Get(adler32, 4) != 4)
88 throw Adler32Err();
89 if (!m_adler32.Verify(adler32))
90 throw Adler32Err();
91}
92
93NAMESPACE_END
void Update(const byte *input, size_t length)
Updates a hash with additional input.
Definition adler32.cpp:8
Interface for buffered transformations.
Definition cryptlib.h:1657
size_t PutWord16(word16 value, ByteOrder order=BIG_ENDIAN_ORDER, bool blocking=true)
Input a 16-bit word for processing.
size_t Put(byte inByte, bool blocking=true)
Input a byte for processing.
Definition cryptlib.h:1678
int GetDeflateLevel() const
Retrieves the deflation level.
Definition zdeflate.h:118
int GetLog2WindowSize() const
Retrieves the window size.
Definition zdeflate.h:122
BufferedTransformation * AttachedTransformation()
Retrieve attached transformation.
Fixed size stack-based SecBlock.
Definition secblock.h:1246
virtual bool Verify(const byte *digest)
Verifies the hash of the current message.
Definition cryptlib.h:1205
virtual void Restart()
Restart the hash.
Definition cryptlib.h:1152
virtual void Final(byte *digest)
Computes the hash of the current message.
Definition cryptlib.h:1147
DEFLATE decompressor (RFC 1951)
Definition zinflate.h:95
ZlibDecompressor(BufferedTransformation *attachment=NULL, bool repeat=false, int autoSignalPropagation=-1)
Construct a ZlibDecompressor.
Definition zlib.cpp:51
unsigned char byte
8-bit unsigned datatype
Definition config_int.h:66
unsigned short word16
16-bit unsigned datatype
Definition config_int.h:69
T1 RoundUpToMultipleOf(const T1 &n, const T2 &m)
Rounds a value up to a multiple of a second value.
Definition misc.h:1384
Crypto++ library namespace.
Precompiled header file.
Classes and functions for secure memory allocations.
#define CRYPTOPP_ASSERT(exp)
Debugging and diagnostic assertion.
Definition trap.h:68
DEFLATE compression and decompression (RFC 1951)
DEFLATE compression and decompression (RFC 1951)
ZLIB compression and decompression (RFC 1950)