mirror of
https://github.com/Unidata/netcdf-c.git
synced 2024-12-03 08:01:25 +08:00
208 lines
6.5 KiB
C
208 lines
6.5 KiB
C
/*********************************************************************
|
|
* Copyright 2018, UCAR/Unidata
|
|
* See netcdf/COPYRIGHT file for copying and redistribution conditions.
|
|
*********************************************************************/
|
|
|
|
#include "d4includes.h"
|
|
#include "d4chunk.h"
|
|
|
|
/**************************************************/
|
|
|
|
/* Header flags */
|
|
#define LAST_CHUNK (1)
|
|
#define ERR_CHUNK (2)
|
|
#define LITTLE_ENDIAN_CHUNK (4)
|
|
#define NOCHECKSUM_CHUNK (8)
|
|
|
|
#define ALL_CHUNK_FLAGS (LAST_CHUNK|ERR_CHUNK|LITTLE_ENDIAN_CHUNK|NOCHECKSUM_CHUNK)
|
|
|
|
/**************************************************/
|
|
|
|
/*
|
|
Given a packet as read from the wire via http (or a file), convert in
|
|
place from chunked format to a single continguous set of bytes. If an
|
|
error packet is recovered, then make that available to the caller and
|
|
return an error. Also return whether the data was big endian encoded
|
|
and whether it has checksums.
|
|
Notes:
|
|
*/
|
|
|
|
/* Define a local struct for convenience */
|
|
struct HDR {unsigned int flags; unsigned int count;};
|
|
|
|
/* Forward */
|
|
static void* getheader(void* p, struct HDR* hdr, int hostlittleendian);
|
|
static int processerrchunk(NCD4meta* metadata, void* errchunk, unsigned int count);
|
|
|
|
/**************************************************/
|
|
|
|
int
|
|
NCD4_dechunk(NCD4meta* metadata)
|
|
{
|
|
unsigned char* p;
|
|
unsigned char* q;
|
|
struct HDR hdr;
|
|
|
|
if(metadata->mode == NCD4_DSR)
|
|
return THROW(NC_EDMR);
|
|
|
|
metadata->serial.errdata = NULL;
|
|
metadata->serial.dmr = NULL;
|
|
metadata->serial.dap = NULL;
|
|
metadata->serial.hostlittleendian = NCD4_isLittleEndian();
|
|
metadata->serial.remotelittleendian = 0; /* do not actually know yet */
|
|
metadata->serial.remotechecksumming = 0; /* do not actually know yet */
|
|
metadata->localchecksumming = 0; /* do not actually know yet */
|
|
|
|
/* Assume proper mode has been inferred already. */
|
|
|
|
/* Verify the mode; assume that the <?xml...?> is optional */
|
|
q = metadata->serial.rawdata;
|
|
if(memcmp(q,"<?xml",strlen("<?xml"))==0
|
|
|| memcmp(q,"<Dataset",strlen("<Dataset"))==0) {
|
|
if(metadata->mode != NCD4_DMR)
|
|
return THROW(NC_EDMR);
|
|
/* setup as dmr only */
|
|
metadata->serial.dmr = (char*)metadata->serial.rawdata; /* temp */
|
|
metadata->serial.dmr[metadata->serial.rawsize-1] = '\0';
|
|
metadata->serial.dmr = strdup((char *)q);
|
|
if(metadata->serial.dmr == NULL)
|
|
return THROW(NC_ENOMEM);
|
|
return THROW(NC_NOERR);
|
|
}
|
|
|
|
/* We must be processing a DAP mode packet */
|
|
p = metadata->serial.rawdata;
|
|
metadata->serial.dap = p;
|
|
|
|
#ifdef D4DUMPRAW
|
|
NCD4_tagdump(metadata->serial.rawsize,metadata->serial.rawdata,0,"RAW");
|
|
#endif
|
|
|
|
/* Get the DMR chunk header*/
|
|
p = getheader(p,&hdr,metadata->serial.hostlittleendian);
|
|
if(hdr.count == 0)
|
|
return THROW(NC_EDMR);
|
|
if(hdr.flags & ERR_CHUNK) {
|
|
return processerrchunk(metadata, (void*)p, hdr.count);
|
|
}
|
|
|
|
metadata->serial.remotechecksumming = ((hdr.flags & NOCHECKSUM_CHUNK) ? 0 : 1);
|
|
metadata->localchecksumming = metadata->serial.remotechecksumming;
|
|
|
|
metadata->serial.remotelittleendian = ((hdr.flags & LITTLE_ENDIAN_CHUNK) ? 1 : 0);
|
|
metadata->serial.dmr = (char*)p;
|
|
metadata->serial.dmr[hdr.count-1] = '\0';
|
|
metadata->serial.dmr = strdup(metadata->serial.dmr);
|
|
if(metadata->serial.dmr == NULL)
|
|
return THROW(NC_ENOMEM);
|
|
p += hdr.count;
|
|
|
|
if(hdr.flags & LAST_CHUNK)
|
|
return THROW(NC_ENODATA);
|
|
/* Read and compress the data chunks */
|
|
q = metadata->serial.dap;
|
|
for(;;) {
|
|
p = getheader(p,&hdr,metadata->serial.hostlittleendian);
|
|
if(hdr.flags & ERR_CHUNK) {
|
|
return processerrchunk(metadata, (void*)p, hdr.count);
|
|
}
|
|
/* data chunk; possibly last; possibly empty */
|
|
if(hdr.count > 0) {
|
|
d4memmove(q,p,hdr.count); /* will overwrite the header */
|
|
p += hdr.count;
|
|
q += hdr.count;
|
|
}
|
|
if(hdr.flags & LAST_CHUNK) break;
|
|
}
|
|
metadata->serial.dapsize = (size_t)DELTA(q,metadata->serial.dap);
|
|
#ifdef D4DUMPDMR
|
|
fprintf(stderr,"%s\n",metadata->serial.dmr);
|
|
fflush(stderr);
|
|
#endif
|
|
#ifdef D4DUMPDAP
|
|
NCD4_tagdump(metadata->serial.dapsize,metadata->serial.dap,0,"DAP");
|
|
#endif
|
|
return THROW(NC_NOERR);
|
|
}
|
|
|
|
static int
|
|
processerrchunk(NCD4meta* metadata, void* errchunk, unsigned int count)
|
|
{
|
|
metadata->serial.errdata = (char*)d4alloc(count+1);
|
|
if(metadata->serial.errdata == NULL)
|
|
return THROW(NC_ENOMEM);
|
|
memcpy(metadata->serial.errdata,errchunk,count);
|
|
metadata->serial.errdata[count] = '\0';
|
|
return THROW(NC_ENODATA); /* slight lie */
|
|
}
|
|
|
|
/* At the moment, the Hyrax test server
|
|
is serving up the chunk data as little endian.
|
|
So use a heuristic to see which endianness
|
|
makes the more sense.
|
|
This fails for very small dap data sections.
|
|
*/
|
|
static void*
|
|
getheader(void* p, struct HDR* hdr, int hostlittleendian)
|
|
{
|
|
unsigned char bytes[4];
|
|
#ifdef HYRAXHACK
|
|
struct HDR hyrax;
|
|
unsigned char orig[4];
|
|
memcpy(orig,p,sizeof(bytes));/* save a copy */
|
|
#endif
|
|
memcpy(bytes,p,sizeof(bytes));
|
|
p = INCR(p,4); /* on-the-wire hdr is 4 bytes */
|
|
/* assume header is network (big) order */
|
|
hdr->flags = bytes[0]; /* big endian => flags are in byte 0 */
|
|
bytes[0] = 0; /* so we can do byte swap to get count */
|
|
if(hostlittleendian)
|
|
swapinline32(bytes); /* host is little endian */
|
|
hdr->count = *(unsigned int*)bytes; /* get count */
|
|
#ifdef HYRAXHACK
|
|
memcpy(bytes,orig,sizeof(bytes)); /* restore */
|
|
hyrax.flags = bytes[3];
|
|
bytes[3] = 0; /* so we can do byte swap to get count */
|
|
if(!hostlittleendian)
|
|
swapinline32(bytes); /* host is big endian */
|
|
hyrax.count = *(unsigned int*)bytes; /* get count */
|
|
/* See which makes more sense */
|
|
if(hyrax.flags <= ALL_CHUNK_FLAGS && hyrax.count >= 0 && hyrax.count < hdr->count) {
|
|
/* Use hyrax version */
|
|
*hdr = hyrax;
|
|
}
|
|
#endif
|
|
return p;
|
|
}
|
|
|
|
/**
|
|
Given a raw response, attempt to infer the mode: DMR, DAP, DSR.
|
|
Since DSR is not standardizes, it becomes the default.
|
|
*/
|
|
int
|
|
NCD4_infermode(NCD4meta* meta)
|
|
{
|
|
d4size_t size = meta->serial.rawsize;
|
|
char* raw = meta->serial.rawdata;
|
|
|
|
if(size < 16)
|
|
return THROW(NC_EDAP); /* must have at least this to hold a hdr + partial dmr*/
|
|
if(memcmp(raw,"<?xml",strlen("<?xml"))==0
|
|
|| memcmp(raw,"<Dataset",strlen("<Dataset"))==0) {
|
|
meta->mode = NCD4_DMR;
|
|
goto done;
|
|
}
|
|
raw += 4; /* Pretend we have a DAP hdr */
|
|
if(memcmp(raw,"<?xml",strlen("<?xml"))==0
|
|
|| memcmp(raw,"<Dataset",strlen("<Dataset"))==0) {
|
|
meta->mode = NCD4_DAP;
|
|
goto done;
|
|
}
|
|
/* Default to DSR */
|
|
meta->mode = NCD4_DSR;
|
|
|
|
done:
|
|
return NC_NOERR;
|
|
}
|