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/*************************************************
* Gzip Compressor Source File *
* (C) 1999-2004 The Botan Project *
* *
* Based on the comp_zlib module, modified *
* by Matt Johnston. This is not a complete *
* gzip implementation (it only handles basic *
* headers). *
*************************************************/
/* This could be implemented a lot more cleanly if we rely on zlib >= 1.2
* being available. the Gzip Compressor would just be a subclass of
* Zlib Compressor, with window_bits+=16 for deflateInit2(), etc */
#include <base.hh>
#include <gzip.hh>
#include <botan/loadstor.h>
#include <botan/filters.h>
#include <botan/bit_ops.h>
#include <cstring>
#include <map>
#include <zlib.h>
namespace Botan {
namespace {
/*************************************************
* Allocation Information for Zlib *
*************************************************/
class Zlib_Alloc_Info
{
public:
std::map<void*, u32bit> current_allocs;
Allocator* alloc;
Zlib_Alloc_Info() { alloc = Allocator::get(false); }
};
/*************************************************
* Allocation Function for Zlib *
*************************************************/
void* zlib_malloc(void* info_ptr, unsigned int n, unsigned int size)
{
Zlib_Alloc_Info* info = static_cast<Zlib_Alloc_Info*>(info_ptr);
void* ptr = info->alloc->allocate(n * size);
info->current_allocs[ptr] = n * size;
return ptr;
}
/*************************************************
* Allocation Function for Zlib *
*************************************************/
void zlib_free(void* info_ptr, void* ptr)
{
Zlib_Alloc_Info* info = static_cast<Zlib_Alloc_Info*>(info_ptr);
std::map<void*, u32bit>::const_iterator i = info->current_allocs.find(ptr);
if(i == info->current_allocs.end())
throw Invalid_Argument("zlib_free: Got pointer not allocated by us");
info->alloc->deallocate(ptr, i->second);
}
}
/*************************************************
* Wrapper Type for Zlib z_stream *
*************************************************/
class Zlib_Stream
{
public:
z_stream stream;
Zlib_Stream()
{
std::memset(&stream, 0, sizeof(z_stream));
stream.zalloc = zlib_malloc;
stream.zfree = zlib_free;
stream.opaque = new Zlib_Alloc_Info;
}
~Zlib_Stream()
{
Zlib_Alloc_Info* info = static_cast<Zlib_Alloc_Info*>(stream.opaque);
delete info;
std::memset(&stream, 0, sizeof(z_stream));
}
};
/*************************************************
* Gzip_Compression Constructor *
*************************************************/
Gzip_Compression::Gzip_Compression(u32bit l) :
level((l >= 9) ? 9 : l), buffer(DEFAULT_BUFFERSIZE),
pipe(new Hash_Filter("CRC32")), count( 0 )
{
zlib = new Zlib_Stream;
// window_bits == -15 relies on an undocumented feature of zlib, which
// supresses the zlib header on the message. We need that since gzip doesn't
// use this header. The feature been confirmed to exist in 1.1.4, which
// everyone should be using due to security fixes. In later versions this
// feature is documented, along with the ability to do proper gzip output
// (that would be a nicer way to do things, but will have to wait until 1.2
// becomes more widespread).
// The other settings are the defaults that deflateInit() gives
if(deflateInit2(&(zlib->stream), level, Z_DEFLATED, -15, 8, Z_DEFAULT_STRATEGY) != Z_OK)
{
delete zlib; zlib = 0;
throw Exception("Gzip_Compression: Memory allocation error");
}
}
/*************************************************
* Gzip_Compression Destructor *
*************************************************/
Gzip_Compression::~Gzip_Compression()
{
deflateEnd(&(zlib->stream));
delete zlib; zlib = 0;
}
/*************************************************
* Start Compressing with Gzip *
*************************************************/
void Gzip_Compression::start_msg()
{
clear();
put_header();
pipe.start_msg();
count = 0;
}
/*************************************************
* Compress Input with Gzip *
*************************************************/
void Gzip_Compression::write(const byte input[], u32bit length)
{
count += length;
pipe.write(input, length);
zlib->stream.next_in = (Bytef*)input;
zlib->stream.avail_in = length;
while(zlib->stream.avail_in != 0)
{
zlib->stream.next_out = (Bytef*)buffer.begin();
zlib->stream.avail_out = buffer.size();
int rc = deflate(&(zlib->stream), Z_NO_FLUSH);
if (rc != Z_OK && rc != Z_STREAM_END)
throw Exception("Internal error in Gzip_Compression deflate.");
send(buffer.begin(), buffer.size() - zlib->stream.avail_out);
}
}
/*************************************************
* Finish Compressing with Gzip *
*************************************************/
void Gzip_Compression::end_msg()
{
zlib->stream.next_in = 0;
zlib->stream.avail_in = 0;
int rc = Z_OK;
while(rc != Z_STREAM_END)
{
zlib->stream.next_out = (Bytef*)buffer.begin();
zlib->stream.avail_out = buffer.size();
rc = deflate(&(zlib->stream), Z_FINISH);
if (rc != Z_OK && rc != Z_STREAM_END)
throw Exception("Internal error in Gzip_Compression finishing deflate.");
send(buffer.begin(), buffer.size() - zlib->stream.avail_out);
}
pipe.end_msg();
put_footer();
clear();
}
/*************************************************
* Clean up Compression Context *
*************************************************/
void Gzip_Compression::clear()
{
deflateReset(&(zlib->stream));
}
/*************************************************
* Put a basic gzip header at the beginning *
*************************************************/
void Gzip_Compression::put_header()
{
send(GZIP::GZIP_HEADER, sizeof(GZIP::GZIP_HEADER));
}
/*************************************************
* Put a gzip footer at the end *
*************************************************/
void Gzip_Compression::put_footer()
{
// 4 byte CRC32, and 4 byte length field
SecureVector<byte> buf(4);
SecureVector<byte> tmpbuf(4);
pipe.read(tmpbuf.begin(), tmpbuf.size(), Pipe::LAST_MESSAGE);
// CRC32 is the reverse order to what gzip expects.
for (int i = 0; i < 4; i++)
buf[3-i] = tmpbuf[i];
send(buf.begin(), buf.size());
// Length - LSB first
for (int i = 0; i < 4; i++)
buf[3-i] = get_byte(i, count);
send(buf.begin(), buf.size());
}
/*************************************************
* Gzip_Decompression Constructor *
*************************************************/
Gzip_Decompression::Gzip_Decompression() : buffer(DEFAULT_BUFFERSIZE),
no_writes(true), pipe(new Hash_Filter("CRC32")), footer(0)
{
if (DEFAULT_BUFFERSIZE < sizeof(GZIP::GZIP_HEADER))
throw Exception("DEFAULT_BUFFERSIZE is too small");
zlib = new Zlib_Stream;
// window_bits == -15 is raw zlib (no header) - see comment
// above about deflateInit2
if(inflateInit2(&(zlib->stream), -15) != Z_OK)
{
delete zlib; zlib = 0;
throw Exception("Gzip_Decompression: Memory allocation error");
}
}
/*************************************************
* Gzip_Decompression Destructor *
*************************************************/
Gzip_Decompression::~Gzip_Decompression()
{
inflateEnd(&(zlib->stream));
delete zlib; zlib = 0;
}
/*************************************************
* Start Decompressing with Gzip *
*************************************************/
void Gzip_Decompression::start_msg()
{
if (!no_writes)
throw Exception("Gzip_Decompression: start_msg after already writing");
pipe.start_msg();
datacount = 0;
pos = 0;
in_footer = false;
}
/*************************************************
* Decompress Input with Gzip *
*************************************************/
void Gzip_Decompression::write(const byte input[], u32bit length)
{
if(length) no_writes = false;
// If we're in the footer, take what we need, then go to the next block
if (in_footer)
{
u32bit eat_len = eat_footer(input, length);
input += eat_len;
length -= eat_len;
if (length == 0)
return;
}
// Check the gzip header
if (pos < sizeof(GZIP::GZIP_HEADER))
{
u32bit len = std::min((u32bit)sizeof(GZIP::GZIP_HEADER)-pos, length);
u32bit cmplen = len;
// The last byte is the OS flag - we don't care about that
if (pos + len - 1 >= GZIP::HEADER_POS_OS)
cmplen--;
if (std::memcmp(input, &GZIP::GZIP_HEADER[pos], cmplen) != 0)
{
throw Decoding_Error("Gzip_Decompression: Data integrity error in header");
}
input += len;
length -= len;
pos += len;
}
pos += length;
zlib->stream.next_in = (Bytef*)input;
zlib->stream.avail_in = length;
while(zlib->stream.avail_in != 0)
{
zlib->stream.next_out = (Bytef*)buffer.begin();
zlib->stream.avail_out = buffer.size();
int rc = inflate(&(zlib->stream), Z_SYNC_FLUSH);
if(rc != Z_OK && rc != Z_STREAM_END)
{
if(rc == Z_DATA_ERROR)
throw Decoding_Error("Gzip_Decompression: Data integrity error");
if(rc == Z_NEED_DICT)
throw Decoding_Error("Gzip_Decompression: Need preset dictionary");
if(rc == Z_MEM_ERROR)
throw Exception("Gzip_Decompression: Memory allocation error");
throw Exception("Gzip_Decompression: Unknown decompress error");
}
send(buffer.begin(), buffer.size() - zlib->stream.avail_out);
pipe.write(buffer.begin(), buffer.size() - zlib->stream.avail_out);
datacount += buffer.size() - zlib->stream.avail_out;
// Reached the end - we now need to check the footer
if(rc == Z_STREAM_END)
{
u32bit read_from_block = length - zlib->stream.avail_in;
u32bit eat_len = eat_footer((Bytef*)input + read_from_block, zlib->stream.avail_in);
read_from_block += eat_len;
input += read_from_block;
length -= read_from_block;
zlib->stream.next_in = (Bytef*)input;
zlib->stream.avail_in = length;
}
}
}
/*************************************************
* Store the footer bytes *
*************************************************/
u32bit Gzip_Decompression::eat_footer(const byte input[], u32bit length)
{
if (footer.size() >= GZIP::FOOTER_LENGTH)
throw Decoding_Error("Gzip_Decompression: Data integrity error in footer");
u32bit eat_len = std::min(GZIP::FOOTER_LENGTH-footer.size(), length);
footer.append(input, eat_len);
if (footer.size() == GZIP::FOOTER_LENGTH)
{
check_footer();
clear();
}
return eat_len;
}
/*************************************************
* Check the gzip footer *
*************************************************/
void Gzip_Decompression::check_footer()
{
if (footer.size() != GZIP::FOOTER_LENGTH)
throw Exception("Gzip_Decompression: Error finalizing decompression");
pipe.end_msg();
// 4 byte CRC32, and 4 byte length field
SecureVector<byte> buf(4);
SecureVector<byte> tmpbuf(4);
pipe.read(tmpbuf.begin(), tmpbuf.size(), Pipe::LAST_MESSAGE);
// CRC32 is the reverse order to what gzip expects.
for (int i = 0; i < 4; i++)
buf[3-i] = tmpbuf[i];
tmpbuf.set(footer.begin(), 4);
if (buf != tmpbuf)
throw Decoding_Error("Gzip_Decompression: Data integrity error - CRC32 error");
// Check the length matches - it is encoded LSB-first
for (int i = 0; i < 4; i++)
{
if (footer.begin()[GZIP::FOOTER_LENGTH-1-i] != get_byte(i, datacount))
throw Decoding_Error("Gzip_Decompression: Data integrity error - incorrect length");
}
}
/*************************************************
* Finish Decompressing with Gzip *
*************************************************/
void Gzip_Decompression::end_msg()
{
// All messages should end with a footer, and when a footer is successfully
// read, clear() will reset no_writes
if(no_writes) return;
throw Exception("Gzip_Decompression: didn't find footer");
}
/*************************************************
* Clean up Decompression Context *
*************************************************/
void Gzip_Decompression::clear()
{
no_writes = true;
inflateReset(&(zlib->stream));
footer.destroy();
pos = 0;
datacount = 0;
}
}
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