[转]解压HTTP gzip的

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <zlib.h>
/* Compress data */
int zcompress(Bytef *data, uLong ndata,
 Bytef *zdata, uLong *nzdata)
{
 z_stream c_stream;
 int err = 0;

 if(data && ndata > 0)
 {
  c_stream.zalloc = (alloc_func)0;
  c_stream.zfree = (free_func)0;
  c_stream.opaque = (voidpf)0;
  if(deflateInit(&c_stream, Z_DEFAULT_COMPRESSION) != Z_OK) return -1;
  c_stream.next_in  = data;
  c_stream.avail_in  = ndata;
  c_stream.next_out = zdata;
  c_stream.avail_out  = *nzdata;
  while (c_stream.avail_in != 0 && c_stream.total_out < *nzdata)
  {
   if(deflate(&c_stream, Z_NO_FLUSH) != Z_OK) return -1;
  }
        if(c_stream.avail_in != 0) return c_stream.avail_in;
  for (;;) {
   if((err = deflate(&c_stream, Z_FINISH)) == Z_STREAM_END) break;
   if(err != Z_OK) return -1;
  }
  if(deflateEnd(&c_stream) != Z_OK) return -1;
  *nzdata = c_stream.total_out;
  return 0;
 }
 return -1;
}

/* Compress gzip data */
int gzcompress(Bytef *data, uLong ndata,
 Bytef *zdata, uLong *nzdata)
{
 z_stream c_stream;
 int err = 0;

 if(data && ndata > 0)
 {
  c_stream.zalloc = (alloc_func)0;
  c_stream.zfree = (free_func)0;
  c_stream.opaque = (voidpf)0;
  if(deflateInit2(&c_stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
                    -MAX_WBITS, 8, Z_DEFAULT_STRATEGY) != Z_OK) return -1;
  c_stream.next_in  = data;
  c_stream.avail_in  = ndata;
  c_stream.next_out = zdata;
  c_stream.avail_out  = *nzdata;
  while (c_stream.avail_in != 0 && c_stream.total_out < *nzdata)
  {
   if(deflate(&c_stream, Z_NO_FLUSH) != Z_OK) return -1;
  }
        if(c_stream.avail_in != 0) return c_stream.avail_in;
  for (;;) {
   if((err = deflate(&c_stream, Z_FINISH)) == Z_STREAM_END) break;
   if(err != Z_OK) return -1;
  }
  if(deflateEnd(&c_stream) != Z_OK) return -1;
  *nzdata = c_stream.total_out;
  return 0;
 }
 return -1;
}

/* Uncompress data */
int zdecompress(Byte *zdata, uLong nzdata,                
        Byte *data, uLong *ndata)
{
 int err = 0;
 z_stream d_stream; /* decompression stream */

 d_stream.zalloc = (alloc_func)0;
 d_stream.zfree = (free_func)0;
 d_stream.opaque = (voidpf)0;
    d_stream.next_in  = zdata;
 d_stream.avail_in = 0;
 d_stream.next_out = data;
 if(inflateInit(&d_stream) != Z_OK) return -1;
 while (d_stream.total_out < *ndata && d_stream.total_in < nzdata) {
  d_stream.avail_in = d_stream.avail_out = 1; /* force small buffers */
  if((err = inflate(&d_stream, Z_NO_FLUSH)) == Z_STREAM_END) break;
  if(err != Z_OK) return -1;
 }
 if(inflateEnd(&d_stream) != Z_OK) return -1;
 *ndata = d_stream.total_out;
 return 0;
}

/* HTTP gzip decompress */
int httpgzdecompress(Byte *zdata, uLong nzdata,                
        Byte *data, uLong *ndata)
{
    int err = 0;
    z_stream d_stream = {0}; /* decompression stream */
    static char dummy_head[2] =
    {
        0x8 + 0x7 * 0x10,
        (((0x8 + 0x7 * 0x10) * 0x100 + 30) / 31 * 31) & 0xFF,
    };
    d_stream.zalloc = (alloc_func)0;
    d_stream.zfree = (free_func)0;
    d_stream.opaque = (voidpf)0;
    d_stream.next_in  = zdata;
    d_stream.avail_in = 0;
    d_stream.next_out = data;
    if(inflateInit2(&d_stream, 47) != Z_OK) return -1;
    while (d_stream.total_out < *ndata && d_stream.total_in < nzdata) {
        d_stream.avail_in = d_stream.avail_out = 1; /* force small buffers */
        if((err = inflate(&d_stream, Z_NO_FLUSH)) == Z_STREAM_END) break;
        if(err != Z_OK )
        {
            if(err == Z_DATA_ERROR)
            {
                d_stream.next_in = (Bytef*) dummy_head;
                d_stream.avail_in = sizeof(dummy_head);
                if((err = inflate(&d_stream, Z_NO_FLUSH)) != Z_OK)
                {
                    return -1;
                }
            }
            else return -1;
        }
    }
    if(inflateEnd(&d_stream) != Z_OK) return -1;
    *ndata = d_stream.total_out;
    return 0;
}

/* Uncompress gzip data */
int gzdecompress(Byte *zdata, uLong nzdata,                
        Byte *data, uLong *ndata)
{
    int err = 0;
    z_stream d_stream = {0}; /* decompression stream */
    static char dummy_head[2] =
    {
        0x8 + 0x7 * 0x10,
        (((0x8 + 0x7 * 0x10) * 0x100 + 30) / 31 * 31) & 0xFF,
    };
    d_stream.zalloc = (alloc_func)0;
    d_stream.zfree = (free_func)0;
    d_stream.opaque = (voidpf)0;
    d_stream.next_in  = zdata;
    d_stream.avail_in = 0;
    d_stream.next_out = data;
    if(inflateInit2(&d_stream, -MAX_WBITS) != Z_OK) return -1;
    //if(inflateInit2(&d_stream, 47) != Z_OK) return -1;
    while (d_stream.total_out < *ndata && d_stream.total_in < nzdata) {
        d_stream.avail_in = d_stream.avail_out = 1; /* force small buffers */
        if((err = inflate(&d_stream, Z_NO_FLUSH)) == Z_STREAM_END) break;
        if(err != Z_OK )
        {
            if(err == Z_DATA_ERROR)
            {
                d_stream.next_in = (Bytef*) dummy_head;
                d_stream.avail_in = sizeof(dummy_head);
                if((err = inflate(&d_stream, Z_NO_FLUSH)) != Z_OK)
                {
                    return -1;
                }
            }
            else return -1;
        }
    }
    if(inflateEnd(&d_stream) != Z_OK) return -1;
    *ndata = d_stream.total_out;
    return 0;
}

#ifdef _DEBUG_ZSTREAM
#define BUF_SIZE 65535
int main()
{
 char *data = "kjdalkfjdflkjdlkfjdklfjdlkfjlkdjflkdjflddajfkdjfkdfaskf;ldsfk;ldakf;ldskfl;dskf;ld"; 
 uLong ndata = strlen(data); 
 Bytef zdata[BUF_SIZE];
 uLong nzdata = BUF_SIZE;
 Bytef  odata[BUF_SIZE];
 uLong nodata = BUF_SIZE;
 
 memset(zdata, 0, BUF_SIZE);
 //if(zcompress((Bytef *)data, ndata, zdata, &nzdata) == 0)
 if(gzcompress((Bytef *)data, ndata, zdata, &nzdata) == 0)
 {
  fprintf(stdout, "nzdata:%d %s\n", nzdata, zdata);
  memset(odata, 0, BUF_SIZE);
  //if(zdecompress(zdata, ndata, odata, &nodata) == 0)
  if(gzdecompress(zdata, ndata, odata, &nodata) == 0)
  {
   fprintf(stdout, "%d %s\n", nodata, odata);
  }
 }
}
#endif