json_t *json_rpc_call(CURL *curl, const char *url,
		      const char *userpass, const char *rpc_req,
		      bool probe, bool longpoll, int *rolltime,
		      struct pool *pool, bool share)
{
	long timeout = longpoll ? (60 * 60) : 60;
	struct data_buffer all_data = {NULL, 0};
	struct header_info hi = {NULL, 0, NULL, NULL, false, false, false};
	char len_hdr[64], user_agent_hdr[128];
	char curl_err_str[CURL_ERROR_SIZE];
	struct curl_slist *headers = NULL;
	struct upload_buffer upload_data;
	json_t *val, *err_val, *res_val;
	bool probing = false;
	double byte_count;
	json_error_t err;
	int rc;

	memset(&err, 0, sizeof(err));

	/* it is assumed that 'curl' is freshly [re]initialized at this pt */

	if (probe)
		probing = !pool->probed;
	curl_easy_setopt(curl, CURLOPT_TIMEOUT, timeout);

	// CURLOPT_VERBOSE won't write to stderr if we use CURLOPT_DEBUGFUNCTION
	curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, curl_debug_cb);
	curl_easy_setopt(curl, CURLOPT_DEBUGDATA, (void *)pool);
	curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);

	curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
	curl_easy_setopt(curl, CURLOPT_URL, url);
	curl_easy_setopt(curl, CURLOPT_ENCODING, "");
	curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);

	/* Shares are staggered already and delays in submission can be costly
	 * so do not delay them */
	if (!opt_delaynet || share)
		curl_easy_setopt(curl, CURLOPT_TCP_NODELAY, 1);
	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, all_data_cb);
	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &all_data);
	curl_easy_setopt(curl, CURLOPT_READFUNCTION, upload_data_cb);
	curl_easy_setopt(curl, CURLOPT_READDATA, &upload_data);
	curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, curl_err_str);
	curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1);
	curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, resp_hdr_cb);
	curl_easy_setopt(curl, CURLOPT_HEADERDATA, &hi);
	curl_easy_setopt(curl, CURLOPT_USE_SSL, CURLUSESSL_TRY);
	if (pool->rpc_proxy) {
		curl_easy_setopt(curl, CURLOPT_PROXY, pool->rpc_proxy);
		curl_easy_setopt(curl, CURLOPT_PROXYTYPE, pool->rpc_proxytype);
	} else if (opt_socks_proxy) {
		curl_easy_setopt(curl, CURLOPT_PROXY, opt_socks_proxy);
		curl_easy_setopt(curl, CURLOPT_PROXYTYPE, CURLPROXY_SOCKS4);
	}
	if (userpass) {
		curl_easy_setopt(curl, CURLOPT_USERPWD, userpass);
		curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
	}
	if (longpoll)
		keep_curlalive(curl);
	curl_easy_setopt(curl, CURLOPT_POST, 1);

	if (opt_protocol)
		applog(LOG_DEBUG, "JSON protocol request:\n%s", rpc_req);

	upload_data.buf = rpc_req;
	upload_data.len = strlen(rpc_req);
	sprintf(len_hdr, "Content-Length: %lu",
		(unsigned long) upload_data.len);
	sprintf(user_agent_hdr, "User-Agent: %s", PACKAGE_STRING);

	headers = curl_slist_append(headers,
		"Content-type: application/json");
	headers = curl_slist_append(headers,
		"X-Mining-Extensions: longpoll midstate rollntime submitold");

	if (likely(global_hashrate)) {
		char ghashrate[255];

		sprintf(ghashrate, "X-Mining-Hashrate: %llu", global_hashrate);
		headers = curl_slist_append(headers, ghashrate);
	}

	headers = curl_slist_append(headers, len_hdr);
	headers = curl_slist_append(headers, user_agent_hdr);
	headers = curl_slist_append(headers, "Expect:"); /* disable Expect hdr*/

	curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

	if (opt_delaynet) {
		/* Don't delay share submission, but still track the nettime */
		if (!share) {
			long long now_msecs, last_msecs;
			struct timeval now, last;

			cgtime(&now);
			last_nettime(&last);
			now_msecs = (long long)now.tv_sec * 1000;
			now_msecs += now.tv_usec / 1000;
			last_msecs = (long long)last.tv_sec * 1000;
			last_msecs += last.tv_usec / 1000;
			if (now_msecs > last_msecs && now_msecs - last_msecs < 250) {
				struct timespec rgtp;

				rgtp.tv_sec = 0;
				rgtp.tv_nsec = (250 - (now_msecs - last_msecs)) * 1000000;
				nanosleep(&rgtp, NULL);
			}
		}
		set_nettime();
	}

	rc = curl_easy_perform(curl);
	if (rc) {
		applog(LOG_INFO, "HTTP request failed: %s", curl_err_str);
		goto err_out;
	}

	if (!all_data.buf) {
		applog(LOG_DEBUG, "Empty data received in json_rpc_call.");
		goto err_out;
	}

	pool->cgminer_pool_stats.times_sent++;
	if (curl_easy_getinfo(curl, CURLINFO_SIZE_UPLOAD, &byte_count) == CURLE_OK)
		pool->cgminer_pool_stats.bytes_sent += byte_count;
	pool->cgminer_pool_stats.times_received++;
	if (curl_easy_getinfo(curl, CURLINFO_SIZE_DOWNLOAD, &byte_count) == CURLE_OK)
		pool->cgminer_pool_stats.bytes_received += byte_count;

	if (probing) {
		pool->probed = true;
		/* If X-Long-Polling was found, activate long polling */
		if (hi.lp_path) {
			if (pool->hdr_path != NULL)
				free(pool->hdr_path);
			pool->hdr_path = hi.lp_path;
		} else
			pool->hdr_path = NULL;
		if (hi.stratum_url) {
			pool->stratum_url = hi.stratum_url;
			hi.stratum_url = NULL;
		}
	} else {
		if (hi.lp_path) {
			free(hi.lp_path);
			hi.lp_path = NULL;
		}
		if (hi.stratum_url) {
			free(hi.stratum_url);
			hi.stratum_url = NULL;
		}
	}

	*rolltime = hi.rolltime;
	pool->cgminer_pool_stats.rolltime = hi.rolltime;
	pool->cgminer_pool_stats.hadrolltime = hi.hadrolltime;
	pool->cgminer_pool_stats.canroll = hi.canroll;
	pool->cgminer_pool_stats.hadexpire = hi.hadexpire;

	val = JSON_LOADS(all_data.buf, &err);
	if (!val) {
		applog(LOG_INFO, "JSON decode failed(%d): %s", err.line, err.text);

		if (opt_protocol)
			applog(LOG_DEBUG, "JSON protocol response:\n%s", (char *)(all_data.buf));

		goto err_out;
	}

	if (opt_protocol) {
		char *s = json_dumps(val, JSON_INDENT(3));

		applog(LOG_DEBUG, "JSON protocol response:\n%s", s);
		free(s);
	}

	/* JSON-RPC valid response returns a non-null 'result',
	 * and a null 'error'.
	 */
	res_val = json_object_get(val, "result");
	err_val = json_object_get(val, "error");

	if (!res_val ||(err_val && !json_is_null(err_val))) {
		char *s;

		if (err_val)
			s = json_dumps(err_val, JSON_INDENT(3));
		else
			s = strdup("(unknown reason)");

		applog(LOG_INFO, "JSON-RPC call failed: %s", s);

		free(s);

		goto err_out;
	}

	if (hi.reason) {
		json_object_set_new(val, "reject-reason", json_string(hi.reason));
		free(hi.reason);
		hi.reason = NULL;
	}
	successful_connect = true;
	databuf_free(&all_data);
	curl_slist_free_all(headers);
	curl_easy_reset(curl);
	return val;

err_out:
	databuf_free(&all_data);
	curl_slist_free_all(headers);
	curl_easy_reset(curl);
	if (!successful_connect)
		applog(LOG_DEBUG, "Failed to connect in json_rpc_call");
	curl_easy_setopt(curl, CURLOPT_FRESH_CONNECT, 1);
	return NULL;
}