Zlib解压c++

Question

我正在使用 zlib，在解压缩时遇到了一些问题。我尝试解压缩进入我的程序的数据包，但只有第一个数据包被正确解压缩。例如：

    //first compressed packet    
        78 5e 72 65 60 08 65 bf cd c0 60 28 98 3f 95 03
        08 18 19 19 25 18 4c af b9 32 38 0a a4 d6 6c 6d
        6c 60 60 04 42 20 60 31 2b c9 37 61 c9 2c 28 33
        e3 cc cd 4c 2e ca 2f ce 4f 2b 61 4e ce cf 65 00
        29 38 c0 03 51 c6 7c 9b 81 e5 40 44 32 23 00
    //first decompressed packet
    //inflate return 0
        45 00 00 55 07 db 00 00 31 11 6f 95 08 08 08 08 
        01 01 01 18 00 35 d6 45 00 41 10 65 7c b5 81 80 
        00 01 00 01 00 00 00 00 04 36 74 6f 34 04 69 70 
        76 36 09 6d 69 63 72 6f 73 6f 66 74 03 63 6f 6d 
        00 00 01 00 01 c0 0c 00 01 00 01 00 00 03 db 00 
        04 c0 58 63 01

但是当我尝试解压缩第二个数据包时 "inflate" 函数 return me -3 并没有解压缩任何东西。第二个压缩包示例：

  //second compressed packet
  //inflate return -3
  72 65 60 f0 62 bf 03 36 74 3e c2 d0 77 cb 19 cc
  de cc d8 18 8c 30 94 b9 20 b1 92 35 33 bf 38 b1
  84 a9 a8 14 c5 24 17 2f 06 96 88 63 e7 ad 01 00

我尝试用参数 MAX_WBITS,-MAX_WBITS,30 初始化 decompressor 但它没有 help.How 我可以解决这个问题吗？代码示例：

//functions
    InitZDecompressor = ( int (WINAPI *)( z_stream_s*, int,const char*,int)) GetProcAddress(zlibdll,"inflateInit2_");
    ZDecompressor = (int (WINAPI *)(z_stream_s*,int)) GetProcAddress(zlibdll,"inflate");
    ResetZDecompressor = (int (WINAPI *)(z_stream_s*)) GetProcAddress(zlibdll,"inflateEnd");

//initialize
__int32 Decoder(unsigned __int8* PDU, unsigned __int32 size, unsigned __int8 * out_b, z_stream_s & stream, bool & IsInit)
{
    if (IsDllLoaded == false || PDU == nullptr) { return 0; }//if Zlib DLL was not loaded, or incoming packet is not cTCP    

    if ( !IsInit )
    {
        SecureZeroMemory(&stream, sizeof(stream));
        auto res = InitZDecompressor( &stream, MAX_WBITS , "1.2.11", sizeof(z_stream_s));//initialize only one time
        IsInit = true;
    }

    stream.next_in = PDU;
    stream.avail_in = size;
    stream.next_out = out_b;
    stream.avail_out = 1048576;
    stream.total_out = 0;

    __int32 ret = 0;
//inflate
    while ( stream.avail_in && ret == 0  )
    { 
        ret = ZDecompressor(&stream, 2);
    }
    return ret;
}
//inflateEnd
void ResetDecompessor(bool & isInit, z_stream_s & stream)
{
    if (isInit){ 

        ResetZDecompressor(&stream);
        isInit = false;
        memset(&stream, 0 ,sizeof(stream));
    }
}
//test func
void testZlib(unsigned __int8 *StPt, __int64 size,z_stream_s & stream,bool & isInit)
{
// StPt - start of compressed data
//size - size of compressed data
//isInit - is zStream already initialize

    unsigned __int8 * OutBuf = new unsigned __int8[ 1048576 ];

    auto res = zlib->Decoder( StPt,size, OutBuf, stream, isInit );

    delete [] OutBuf;
}

Answer 1

这里发生的事情是发送方用一个空的存储块刷新 deflate 压缩器以产生一个可解压缩的数据包，然后删除空存储块的最后四个字节，期望你，接收方，插入那个。

所以你需要做的是在压缩数据包之间插入字节 00 00 ff ff，然后将整个东西解压为一个 zlib 流。不要为第二个数据包初始化 inflate——只是继续向 inflator 提供压缩数据（包括插入的字节）。

Zlib解压c++

Zlib decompression c++

c++

compression

zlib

deflate

inflate