clixon/util/clixon_util_stream.c

/*
 *
  ***** BEGIN LICENSE BLOCK *****
 
  Copyright (C) 2009-2018 Olof Hagsand and Benny Holmgren

  This file is part of CLIXON.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  Alternatively, the contents of this file may be used under the terms of
  the GNU General Public License Version 3 or later (the "GPL"),
  in which case the provisions of the GPL are applicable instead
  of those above. If you wish to allow use of your version of this file only
  under the terms of the GPL, and not to allow others to
  use your version of this file under the terms of Apache License version 2, 
  indicate your decision by deleting the provisions above and replace them with
  the  notice and other provisions required by the GPL. If you do not delete
  the provisions above, a recipient may use your version of this file under
  the terms of any one of the Apache License version 2 or the GPL.

  ***** END LICENSE BLOCK *****

 * Stream restconf support functions.
 * (Original in grideye)
 * Example: clixon_util_stream http://localhost/streams/EXAMPLE 10
 */

#ifdef HAVE_CONFIG_H
#include "clixon_config.h" /* generated by config & autoconf */
#endif

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <limits.h>
#include <fnmatch.h>
#include <stdint.h>
#include <assert.h>
#include <curl/curl.h>

/* cligen */
#include <cligen/cligen.h>

/* clixon */
#include "clixon/clixon.h"

/*
 * Types (curl)
 */
struct curlbuf{
    size_t b_len;
    char  *b_buf;
};

/*
 * For the asynchronous case. I think we must handle the case where of many of these
 * come in before we can handle them in the upper-level polling routine.
 * realloc. Therefore, we append new data to the userdata buffer.
 */
static size_t
curl_get_cb(void *ptr, 
	    size_t size, 
	    size_t nmemb, 
	    void *userdata)
{
    struct curlbuf *buf = (struct curlbuf *)userdata;
    int len;

    len = size*nmemb;
    if ((buf->b_buf = realloc(buf->b_buf, buf->b_len+len+1)) == NULL)
	return 0;
    memcpy(buf->b_buf+buf->b_len, ptr, len);
    buf->b_len += len;
    buf->b_buf[buf->b_len] = '\0';
    //    fprintf(stderr, "%s\n", buf->b_buf);
    return len;
}

/*! Given an URL and data to post, do a (curl) get request with data.
 *
 * If getdata is set, return the (malloced) data (which should be freed).
 *
 * @param[in] query 'q' parameter that should be URL-encoded, ie ?q=<encoded>
 *                   XXX: dont add q=, there may be more parameters.
 * @retval    -1    fatal error
 * @retval     1    ok
 *
 * @note curl_easy_perform blocks
 * @note New handle is created every time, the handle can be re-used for 
 * better TCP performance
 */
int
url_get(char  *url, 
	char  *query, 
	int    timeout,
	char **getdata)
{
    int        retval = -1;
    CURL      *curl;
    char      *err = NULL;
    char      *encoded = NULL;
    struct curlbuf cb = {0, };
    cbuf      *cbf = NULL;
    struct curl_slist *list = NULL;
    int       ret;

    clicon_debug(1, "%s:  curl -G %s", __FUNCTION__, url);
    /* Set up curl for doing the communication with the controller */
    if ((curl = curl_easy_init()) == NULL) {
	clicon_err(OE_PLUGIN, errno, "curl_easy_init");
	goto done;
    }
    if ((cbf = cbuf_new()) == NULL)
	goto done;

    if (query){
	if ((encoded = curl_easy_escape(curl, query, 0)) == NULL){
	    clicon_debug(1, "curl_easy_escape");
	    goto done;
	}
    }
    if ((err = malloc(CURL_ERROR_SIZE)) == NULL) {
	clicon_debug(1, "%s: malloc", __FUNCTION__);
	goto done;
    }
    /* specify URL to get */ 
    if (query)
	cprintf(cbf, "%s?q=%s", url, encoded);
    else
	cprintf(cbf, "%s", url);
    curl_easy_setopt(curl, CURLOPT_HTTPGET, 1L);
    list = curl_slist_append(list, "Accept: text/event-stream");
    list = curl_slist_append(list, "Cache-Control: no-cache");
    list = curl_slist_append(list, "Connection: keep-alive");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);

    /* For reference, this url works 
       "http://192.36.171.239:8086/db/nordunet/series?q=select%20tcmp2%20from%20%22dk-ore%22%20limit%201"
    */
    clicon_debug(1, "url: %s\n", cbuf_get(cbf));
    curl_easy_setopt(curl, CURLOPT_URL, cbuf_get(cbf));
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, curl_get_cb);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &cb);
    
    /* some servers don't like requests that are made without a user-agent
       field, so we provide one */ 

    curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, err);
    //    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, timeout);
    //    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 10L);
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, 10L);
    curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 1L);  
    ret = curl_easy_perform(curl);
    if (ret != CURLE_OPERATION_TIMEDOUT && ret != CURLE_OK){
	fprintf(stderr, "curl: %s %d", err, ret);
	goto done;
    }
    if (getdata && cb.b_buf){
	*getdata = cb.b_buf;
	cb.b_buf = NULL;
    }
    retval = 1;
  done:
    if (cbf)
	cbuf_free(cbf);
    if (err)
	free(err);
    if (encoded)
	curl_free(encoded);
    if (cb.b_buf)
	free(cb.b_buf);
    if (curl)
	curl_easy_cleanup(curl);   /* cleanup */ 
    return retval;
}

static int
usage(char *argv0)
{
    fprintf(stderr, "usage:%s <url> <timeout>.\n\tInput on stdin\n", argv0);
    exit(0);
}

int
main(int argc, char **argv)
{
    cbuf  *cb = cbuf_new();
    char  *url;
    char  *query = NULL;
    char  *getdata = NULL;
    int    timeout;

    if (argc != 3){
	usage(argv[0]);
	return 0;
    }
    url = argv[1];
    timeout = atoi(argv[2]);
    if (url_get(url, query, timeout, &getdata) < 0)
	goto done;
    fprintf(stdout, "%s", getdata);
    fflush(stdout);
 done:
    if (getdata)
	free(getdata);
    if (cb)
	cbuf_free(cb);
    return 0;
}