mirror of
https://github.com/Unidata/netcdf-c.git
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422 lines
10 KiB
C
422 lines
10 KiB
C
/**
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* @file
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*
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* Read a range of data from a remote dataset.
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*
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* Copyright 2018 University Corporation for Atmospheric
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* Research/Unidata. See COPYRIGHT file for more info.
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*/
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#include "config.h"
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#define CURL_DISABLE_TYPECHECK 1
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#include <curl/curl.h>
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#include "netcdf.h"
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#include "nclog.h"
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#include "ncbytes.h"
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#include "nclist.h"
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#include "nchttp.h"
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#undef TRACE
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#define CURLERR(e) (e)
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/* Mnemonics */
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#define GETCMD 0
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#define HEADCMD 1
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static const char* LENGTH_ACCEPT[] = {"content-length","accept-ranges",NULL};
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static const char* CONTENTLENGTH[] = {"content-length",NULL};
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/* Forward */
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static int setupconn(NC_HTTP_STATE* state, const char* objecturl, NCbytes* buf);
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static int execute(NC_HTTP_STATE* state, int headcmd);
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static int headerson(NC_HTTP_STATE* state, const char** which);
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static void headersoff(NC_HTTP_STATE* state);
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#ifdef TRACE
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static void
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dbgflush() {
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fflush(stderr);
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fflush(stdout);
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}
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static void
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Trace(const char* fcn)
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{
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fprintf(stdout,"xxx: %s\n",fcn);
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dbgflush();
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}
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#else
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#define dbgflush()
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#define Trace(fcn)
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#endif /*TRACE*/
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/**************************************************/
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/**
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@param objecturl url we propose to access
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@param curlp curl handle stored here if non-NULL
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@param filelenp store length of the file here if non-NULL
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*/
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int
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nc_http_open(const char* objecturl, NC_HTTP_STATE** statep, size64_t* filelenp)
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{
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int stat = NC_NOERR;
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int i;
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NC_HTTP_STATE* state = NULL;
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Trace("open");
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if((state = calloc(1,sizeof(NC_HTTP_STATE))) == NULL)
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{stat = NC_ENOMEM; goto done;}
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/* initialize curl*/
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state->curl = curl_easy_init();
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if (state->curl == NULL) {stat = NC_ECURL; goto done;}
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if(filelenp) {
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*filelenp = -1;
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/* Attempt to get the file length using HEAD */
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if((stat = setupconn(state,objecturl,NULL))) goto done;
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if((stat = headerson(state,LENGTH_ACCEPT))) goto done;
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if((stat = execute(state,HEADCMD))) goto done;
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for(i=0;i<nclistlength(state->headers);i+=2) {
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char* s = nclistget(state->headers,i);
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if(strcasecmp(s,"content-length")==0) {
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s = nclistget(state->headers,i+1);
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sscanf(s,"%lld",filelenp);
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break;
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}
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/* Also check for the Accept-Ranges header */
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if(strcasecmp(s,"accept-ranges")==0) {
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s = nclistget(state->headers,i+1);
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if(strcasecmp(s,"bytes")!=0) /* oops! */
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{stat = NC_EURL; goto done;}
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}
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}
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headersoff(state);
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}
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if(statep) {*statep = state; state = NULL;}
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done:
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nc_http_close(state);
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dbgflush();
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return stat;
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}
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int
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nc_http_close(NC_HTTP_STATE* state)
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{
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int stat = NC_NOERR;
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Trace("close");
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if(state == NULL) return stat;
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if(state->curl != NULL)
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(void)curl_easy_cleanup(state->curl);
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nclistfreeall(state->headers); state->headers = NULL;
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if(state->buf != NULL)
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abort();
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nullfree(state);
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dbgflush();
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return stat;
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}
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/**
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Assume URL etc has already been set.
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@param curl curl handle
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@param start starting offset
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@param count number of bytes to read
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@param buf store read data here -- caller must allocate and free
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*/
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int
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nc_http_read(NC_HTTP_STATE* state, const char* objecturl, size64_t start, size64_t count, NCbytes* buf)
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{
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int stat = NC_NOERR;
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char range[64];
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CURLcode cstat = CURLE_OK;
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Trace("read");
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if(count == 0)
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goto done; /* do not attempt to read */
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if((stat = setupconn(state,objecturl,buf)))
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goto fail;
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/* Set to read byte range */
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snprintf(range,sizeof(range),"%ld-%ld",(long)start,(long)((start+count)-1));
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_RANGE, range));
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if(cstat != CURLE_OK)
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{stat = NC_ECURL; goto done;}
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if((stat = execute(state,GETCMD)))
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goto done;
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done:
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state->buf = NULL;
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dbgflush();
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return stat;
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fail:
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stat = NC_ECURL;
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goto done;
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}
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/**
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Return length of an object.
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Assume URL etc has already been set.
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@param curl curl handle
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*/
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int
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nc_http_size(NC_HTTP_STATE* state, const char* objecturl, size64_t* sizep)
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{
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int i,stat = NC_NOERR;
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Trace("size");
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if(sizep == NULL)
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goto done; /* do not attempt to read */
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if((stat = setupconn(state,objecturl,NULL)))
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goto done;
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/* Make sure we get headers */
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if((stat = headerson(state,CONTENTLENGTH))) goto done;
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state->httpcode = 200;
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if((stat = execute(state,HEADCMD)))
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goto done;
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if(nclistlength(state->headers) == 0)
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{stat = NC_EURL; goto done;}
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/* Get the content length header */
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for(i=0;i<nclistlength(state->headers);i+=2) {
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char* s = nclistget(state->headers,i);
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if(strcasecmp(s,"content-length")==0) {
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s = nclistget(state->headers,i+1);
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sscanf(s,"%llu",sizep);
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break;
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}
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}
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done:
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headersoff(state);
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dbgflush();
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return stat;
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}
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int
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nc_http_headers(NC_HTTP_STATE* state, const NClist** headersp)
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{
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if(headersp) *headersp = state->headers;
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return NC_NOERR;
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}
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/**************************************************/
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static size_t
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WriteMemoryCallback(void *ptr, size_t size, size_t nmemb, void *data)
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{
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NC_HTTP_STATE* state = data;
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size_t realsize = size * nmemb;
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Trace("WriteMemoryCallback");
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if(realsize == 0)
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nclog(NCLOGWARN,"WriteMemoryCallback: zero sized chunk");
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ncbytesappendn(state->buf, ptr, realsize);
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return realsize;
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}
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static void
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trim(char* s)
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{
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size_t l = strlen(s);
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char* p = s;
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char* q = s + l;
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if(l == 0) return;
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q--; /* point to last char of string */
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/* Walk backward to first non-whitespace */
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for(;q > p;q--) {
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if(*q > ' ') break; /* found last non-whitespace */
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}
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/* invariant: p == q || *q > ' ' */
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if(p == q) /* string is all whitespace */
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{*p = '\0';}
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else {/* *q is last non-whitespace */
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q++; /* point to actual whitespace */
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*q = '\0';
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}
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/* Ok, skip past leading whitespace */
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for(p=s;*p;p++) {if(*p > ' ') break;}
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/* invariant: *p == '\0' || *p > ' ' */
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if(*p == 0) return; /* no leading whitespace */
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/* Ok, overwrite any leading whitespace */
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for(q=s;*p;) {*q++ = *p++;}
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*q = '\0';
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return;
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}
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static size_t
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HeaderCallback(char *buffer, size_t size, size_t nitems, void *data)
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{
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size_t realsize = size * nitems;
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char* name = NULL;
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char* value = NULL;
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char* p = NULL;
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size_t i;
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int havecolon;
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NC_HTTP_STATE* state = data;
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int match;
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const char** hdr;
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Trace("HeaderCallback");
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if(realsize == 0)
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nclog(NCLOGWARN,"HeaderCallback: zero sized chunk");
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i = 0;
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/* Look for colon separator */
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for(p=buffer;(i < realsize) && (*p != ':');p++,i++);
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havecolon = (i < realsize);
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if(i == 0)
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nclog(NCLOGWARN,"HeaderCallback: malformed header: %s",buffer);
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name = malloc(i+1);
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memcpy(name,buffer,i);
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name[i] = '\0';
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if(state->headset != NULL) {
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for(match=0,hdr=state->headset;*hdr;hdr++) {
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if(strcasecmp(*hdr,name)==0) {match = 1; break;}
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}
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if(!match) goto done;
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}
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/* Capture this header */
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value = NULL;
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if(havecolon) {
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size_t vlen = (realsize - i);
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value = malloc(vlen+1);
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p++; /* skip colon */
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memcpy(value,p,vlen);
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value[vlen] = '\0';
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trim(value);
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}
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if(state->headers == NULL)
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state->headers = nclistnew();
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nclistpush(state->headers,name);
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name = NULL;
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if(value == NULL) value = strdup("");
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nclistpush(state->headers,value);
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value = NULL;
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done:
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nullfree(name);
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return realsize;
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}
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static int
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setupconn(NC_HTTP_STATE* state, const char* objecturl, NCbytes* buf)
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{
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int stat = NC_NOERR;
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CURLcode cstat = CURLE_OK;
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if(objecturl != NULL) {
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/* Set the URL */
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_URL, (void*)objecturl));
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if (cstat != CURLE_OK) goto fail;
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}
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/* Set options */
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, 100)); /* 30sec timeout*/
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if (cstat != CURLE_OK) goto fail;
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_CONNECTTIMEOUT, 100));
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if (cstat != CURLE_OK) goto fail;
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_NOPROGRESS, 1));
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if (cstat != CURLE_OK) goto fail;
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cstat = curl_easy_setopt(state->curl, CURLOPT_FOLLOWLOCATION, 1);
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if (cstat != CURLE_OK) goto fail;
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state->buf = buf;
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if(buf != NULL) {
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/* send all data to this function */
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, WriteMemoryCallback));
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if (cstat != CURLE_OK) goto fail;
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/* Set argument for WriteMemoryCallback */
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, (void*)state));
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if (cstat != CURLE_OK) goto fail;
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} else {/* turn off data capture */
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(void)CURLERR(curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, NULL));
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(void)CURLERR(curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, NULL));
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}
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done:
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return stat;
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fail:
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/* Turn off header capture */
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headersoff(state);
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stat = NC_ECURL;
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goto done;
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}
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static int
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execute(NC_HTTP_STATE* state, int headcmd)
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{
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int stat = NC_NOERR;
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CURLcode cstat = CURLE_OK;
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if(headcmd) {
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_NOBODY, 1L));
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if(cstat != CURLE_OK) goto fail;
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}
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cstat = CURLERR(curl_easy_perform(state->curl));
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if(cstat != CURLE_OK) goto fail;
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cstat = CURLERR(curl_easy_getinfo(state->curl,CURLINFO_RESPONSE_CODE,&state->httpcode));
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if(cstat != CURLE_OK) state->httpcode = 0;
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if(headcmd) {
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_HTTPGET, 1L));
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if(cstat != CURLE_OK) goto fail;
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}
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done:
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return stat;
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fail:
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stat = NC_ECURL;
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goto done;
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}
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static int
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headerson(NC_HTTP_STATE* state, const char** headset)
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{
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int stat = NC_NOERR;
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CURLcode cstat = CURLE_OK;
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if(state->headers != NULL)
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nclistfreeall(state->headers);
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state->headers = nclistnew();
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state->headset = headset;
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_HEADERFUNCTION, HeaderCallback));
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if(cstat != CURLE_OK) goto fail;
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cstat = CURLERR(curl_easy_setopt(state->curl, CURLOPT_HEADERDATA, (void*)state));
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if (cstat != CURLE_OK) goto fail;
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done:
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return stat;
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fail:
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stat = NC_ECURL;
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goto done;
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}
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static void
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headersoff(NC_HTTP_STATE* state)
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{
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nclistfreeall(state->headers);
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state->headers = NULL;
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(void)CURLERR(curl_easy_setopt(state->curl, CURLOPT_HEADERFUNCTION, NULL));
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(void)CURLERR(curl_easy_setopt(state->curl, CURLOPT_HEADERDATA, NULL));
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}
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