sgminer/util.c

/*
 * Copyright 2011-2012 Con Kolivas
 * Copyright 2010 Jeff Garzik
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 3 of the License, or (at your option)
 * any later version.  See COPYING for more details.
 */

#define _GNU_SOURCE
#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdarg.h>
#include <string.h>
#include <jansson.h>
#include <curl/curl.h>
#include <time.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#ifndef WIN32
# include <sys/socket.h>
# include <netinet/in.h>
# include <netinet/tcp.h>
#else
# include <winsock2.h>
# include <mstcpip.h>
#endif
#include <netdb.h>

#include "miner.h"
#include "elist.h"
#include "compat.h"

#if JANSSON_MAJOR_VERSION >= 2
#define JSON_LOADS(str, err_ptr) json_loads((str), 0, (err_ptr))
#else
#define JSON_LOADS(str, err_ptr) json_loads((str), (err_ptr))
#endif

bool successful_connect = false;
struct timeval nettime;

struct data_buffer {
	void		*buf;
	size_t		len;
};

struct upload_buffer {
	const void	*buf;
	size_t		len;
};

struct header_info {
	char		*lp_path;
	int		rolltime;
	char		*reason;
	bool		hadrolltime;
	bool		canroll;
	bool		hadexpire;
};

struct tq_ent {
	void			*data;
	struct list_head	q_node;
};

static void databuf_free(struct data_buffer *db)
{
	if (!db)
		return;

	free(db->buf);

	memset(db, 0, sizeof(*db));
}

static size_t all_data_cb(const void *ptr, size_t size, size_t nmemb,
			  void *user_data)
{
	struct data_buffer *db = user_data;
	size_t len = size * nmemb;
	size_t oldlen, newlen;
	void *newmem;
	static const unsigned char zero = 0;

	oldlen = db->len;
	newlen = oldlen + len;

	newmem = realloc(db->buf, newlen + 1);
	if (!newmem)
		return 0;

	db->buf = newmem;
	db->len = newlen;
	memcpy(db->buf + oldlen, ptr, len);
	memcpy(db->buf + newlen, &zero, 1);	/* null terminate */

	return len;
}

static size_t upload_data_cb(void *ptr, size_t size, size_t nmemb,
			     void *user_data)
{
	struct upload_buffer *ub = user_data;
	unsigned int len = size * nmemb;

	if (len > ub->len)
		len = ub->len;

	if (len) {
		memcpy(ptr, ub->buf, len);
		ub->buf += len;
		ub->len -= len;
	}

	return len;
}

static size_t resp_hdr_cb(void *ptr, size_t size, size_t nmemb, void *user_data)
{
	struct header_info *hi = user_data;
	size_t remlen, slen, ptrlen = size * nmemb;
	char *rem, *val = NULL, *key = NULL;
	void *tmp;

	val = calloc(1, ptrlen);
	key = calloc(1, ptrlen);
	if (!key || !val)
		goto out;

	tmp = memchr(ptr, ':', ptrlen);
	if (!tmp || (tmp == ptr))	/* skip empty keys / blanks */
		goto out;
	slen = tmp - ptr;
	if ((slen + 1) == ptrlen)	/* skip key w/ no value */
		goto out;
	memcpy(key, ptr, slen);		/* store & nul term key */
	key[slen] = 0;

	rem = ptr + slen + 1;		/* trim value's leading whitespace */
	remlen = ptrlen - slen - 1;
	while ((remlen > 0) && (isspace(*rem))) {
		remlen--;
		rem++;
	}

	memcpy(val, rem, remlen);	/* store value, trim trailing ws */
	val[remlen] = 0;
	while ((*val) && (isspace(val[strlen(val) - 1])))
		val[strlen(val) - 1] = 0;

	if (!*val)			/* skip blank value */
		goto out;

	if (opt_protocol)
		applog(LOG_DEBUG, "HTTP hdr(%s): %s", key, val);

	if (!strcasecmp("X-Roll-Ntime", key)) {
		hi->hadrolltime = true;
		if (!strncasecmp("N", val, 1))
			applog(LOG_DEBUG, "X-Roll-Ntime: N found");
		else {
			hi->canroll = true;

			/* Check to see if expire= is supported and if not, set
			 * the rolltime to the default scantime */
			if (strlen(val) > 7 && !strncasecmp("expire=", val, 7)) {
				sscanf(val + 7, "%d", &hi->rolltime);
				hi->hadexpire = true;
			} else
				hi->rolltime = opt_scantime;
			applog(LOG_DEBUG, "X-Roll-Ntime expiry set to %d", hi->rolltime);
		}
	}

	if (!strcasecmp("X-Long-Polling", key)) {
		hi->lp_path = val;	/* steal memory reference */
		val = NULL;
	}

	if (!strcasecmp("X-Reject-Reason", key)) {
		hi->reason = val;	/* steal memory reference */
		val = NULL;
	}

out:
	free(key);
	free(val);
	return ptrlen;
}

#ifdef CURL_HAS_SOCKOPT
int json_rpc_call_sockopt_cb(void __maybe_unused *userdata, curl_socket_t fd,
			     curlsocktype __maybe_unused purpose)
{
	int tcp_keepidle = 120;
	int tcp_keepintvl = 120;

#ifndef WIN32
	int keepalive = 1;
	int tcp_keepcnt = 5;

	if (unlikely(setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof(keepalive))))
		return 1;

# ifdef __linux

	if (unlikely(setsockopt(fd, SOL_TCP, TCP_KEEPCNT, &tcp_keepcnt, sizeof(tcp_keepcnt))))
		return 1;

	if (unlikely(setsockopt(fd, SOL_TCP, TCP_KEEPIDLE, &tcp_keepidle, sizeof(tcp_keepidle))))
		return 1;

	if (unlikely(setsockopt(fd, SOL_TCP, TCP_KEEPINTVL, &tcp_keepintvl, sizeof(tcp_keepintvl))))
		return 1;
# endif /* __linux */
# ifdef __APPLE_CC__

	if (unlikely(setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE, &tcp_keepintvl, sizeof(tcp_keepintvl))))
		return 1;

# endif /* __APPLE_CC__ */

#else /* WIN32 */

	struct tcp_keepalive vals;
	vals.onoff = 1;
	vals.keepalivetime = tcp_keepidle * 1000;
	vals.keepaliveinterval = tcp_keepintvl * 1000;

	DWORD outputBytes;

	if (unlikely(WSAIoctl(fd, SIO_KEEPALIVE_VALS, &vals, sizeof(vals), NULL, 0, &outputBytes, NULL, NULL)))
		return 1;

#endif /* WIN32 */

	return 0;
}
#endif

static void last_nettime(struct timeval *last)
{
	rd_lock(&netacc_lock);
	last->tv_sec = nettime.tv_sec;
	last->tv_usec = nettime.tv_usec;
	rd_unlock(&netacc_lock);
}

static void set_nettime(void)
{
	wr_lock(&netacc_lock);
	gettimeofday(&nettime, NULL);
	wr_unlock(&netacc_lock);
}

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, 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;
	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);

#if 0 /* Disable curl debugging since it spews to stderr */
	if (opt_protocol)
		curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
#endif
	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);
	}
#ifdef CURL_HAS_SOCKOPT
	if (longpoll)
		curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, json_rpc_call_sockopt_cb);
#endif
	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;

			gettimeofday(&now, NULL);
			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;
	}

	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;
	} else if (hi.lp_path) {
		free(hi.lp_path);
		hi.lp_path = 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", 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 || json_is_null(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;
}

#if (LIBCURL_VERSION_MAJOR == 7 && LIBCURL_VERSION_MINOR >= 10) || (LIBCURL_VERSION_MAJOR > 7)
static struct {
	const char *name;
	curl_proxytype proxytype;
} proxynames[] = {
	{ "http:",	CURLPROXY_HTTP },
#if (LIBCURL_VERSION_MAJOR > 7) || (LIBCURL_VERSION_MINOR > 19) || (LIBCURL_VERSION_MINOR == 19 && LIBCURL_VERSION_PATCH >= 4)
	{ "http0:",	CURLPROXY_HTTP_1_0 },
#endif
#if (LIBCURL_VERSION_MAJOR > 7) || (LIBCURL_VERSION_MINOR > 15) || (LIBCURL_VERSION_MINOR == 15 && LIBCURL_VERSION_PATCH >= 2)
	{ "socks4:",	CURLPROXY_SOCKS4 },
#endif
	{ "socks5:",	CURLPROXY_SOCKS5 },
#if (LIBCURL_VERSION_MAJOR > 7) || (LIBCURL_VERSION_MINOR >= 18)
	{ "socks4a:",	CURLPROXY_SOCKS4A },
	{ "socks5h:",	CURLPROXY_SOCKS5_HOSTNAME },
#endif
	{ NULL,	0 }
};
#endif

const char *proxytype(curl_proxytype proxytype)
{
	int i;

	for (i = 0; proxynames[i].name; i++)
		if (proxynames[i].proxytype == proxytype)
			return proxynames[i].name;

	return "invalid";
}

char *get_proxy(char *url, struct pool *pool)
{
	pool->rpc_proxy = NULL;

#if (LIBCURL_VERSION_MAJOR == 7 && LIBCURL_VERSION_MINOR >= 10) || (LIBCURL_VERSION_MAJOR > 7)
	char *split;
	int plen, len, i;

	for (i = 0; proxynames[i].name; i++) {
		plen = strlen(proxynames[i].name);
		if (strncmp(url, proxynames[i].name, plen) == 0) {
			if (!(split = strchr(url, '|')))
				return url;

			*split = '\0';
			len = split - url;
			pool->rpc_proxy = malloc(1 + len - plen);
			if (!(pool->rpc_proxy))
				quit(1, "Failed to malloc rpc_proxy");

			strcpy(pool->rpc_proxy, url + plen);
			pool->rpc_proxytype = proxynames[i].proxytype;
			url = split + 1;
			break;
		}
	}
#endif
	return url;
}


char *bin2hex(const unsigned char *p, size_t len)
{
	char *s = malloc((len * 2) + 1);
	unsigned int i;

	if (!s)
		return NULL;

	for (i = 0; i < len; i++)
		sprintf(s + (i * 2), "%02x", (unsigned int) p[i]);

	return s;
}

bool hex2bin(unsigned char *p, const char *hexstr, size_t len)
{
	while (*hexstr && len) {
		char hex_byte[3];
		unsigned int v;

		if (!hexstr[1]) {
			applog(LOG_ERR, "hex2bin str truncated");
			return false;
		}

		hex_byte[0] = hexstr[0];
		hex_byte[1] = hexstr[1];
		hex_byte[2] = 0;

		if (sscanf(hex_byte, "%x", &v) != 1) {
			applog(LOG_ERR, "hex2bin sscanf '%s' failed", hex_byte);
			return false;
		}

		*p = (unsigned char) v;

		p++;
		hexstr += 2;
		len--;
	}

	return (len == 0 && *hexstr == 0) ? true : false;
}

bool fulltest(const unsigned char *hash, const unsigned char *target)
{
	unsigned char hash_swap[32], target_swap[32];
	uint32_t *hash32 = (uint32_t *) hash_swap;
	uint32_t *target32 = (uint32_t *) target_swap;
	char *hash_str, *target_str;
	bool rc = true;
	int i;

	swap256(hash_swap, hash);
	swap256(target_swap, target);

	for (i = 0; i < 32/4; i++) {
		uint32_t h32tmp = swab32(hash32[i]);
		uint32_t t32tmp = target32[i];

		target32[i] = swab32(target32[i]);	/* for printing */

		if (h32tmp > t32tmp) {
			rc = false;
			break;
		}
		if (h32tmp < t32tmp) {
			rc = true;
			break;
		}
	}

	if (opt_debug) {
		hash_str = bin2hex(hash_swap, 32);
		target_str = bin2hex(target_swap, 32);

		applog(LOG_DEBUG, " Proof: %s\nTarget: %s\nTrgVal? %s",
			hash_str,
			target_str,
			rc ? "YES (hash < target)" :
			     "no (false positive; hash > target)");

		free(hash_str);
		free(target_str);
	}

	return rc;
}

struct thread_q *tq_new(void)
{
	struct thread_q *tq;

	tq = calloc(1, sizeof(*tq));
	if (!tq)
		return NULL;

	INIT_LIST_HEAD(&tq->q);
	pthread_mutex_init(&tq->mutex, NULL);
	pthread_cond_init(&tq->cond, NULL);

	return tq;
}

void tq_free(struct thread_q *tq)
{
	struct tq_ent *ent, *iter;

	if (!tq)
		return;

	list_for_each_entry_safe(ent, iter, &tq->q, q_node) {
		list_del(&ent->q_node);
		free(ent);
	}

	pthread_cond_destroy(&tq->cond);
	pthread_mutex_destroy(&tq->mutex);

	memset(tq, 0, sizeof(*tq));	/* poison */
	free(tq);
}

static void tq_freezethaw(struct thread_q *tq, bool frozen)
{
	mutex_lock(&tq->mutex);

	tq->frozen = frozen;

	pthread_cond_signal(&tq->cond);
	mutex_unlock(&tq->mutex);
}

void tq_freeze(struct thread_q *tq)
{
	tq_freezethaw(tq, true);
}

void tq_thaw(struct thread_q *tq)
{
	tq_freezethaw(tq, false);
}

bool tq_push(struct thread_q *tq, void *data)
{
	struct tq_ent *ent;
	bool rc = true;

	ent = calloc(1, sizeof(*ent));
	if (!ent)
		return false;

	ent->data = data;
	INIT_LIST_HEAD(&ent->q_node);

	mutex_lock(&tq->mutex);

	if (!tq->frozen) {
		list_add_tail(&ent->q_node, &tq->q);
	} else {
		free(ent);
		rc = false;
	}

	pthread_cond_signal(&tq->cond);
	mutex_unlock(&tq->mutex);

	return rc;
}

void *tq_pop(struct thread_q *tq, const struct timespec *abstime)
{
	struct tq_ent *ent;
	void *rval = NULL;
	int rc;

	mutex_lock(&tq->mutex);

	if (!list_empty(&tq->q))
		goto pop;

	if (abstime)
		rc = pthread_cond_timedwait(&tq->cond, &tq->mutex, abstime);
	else
		rc = pthread_cond_wait(&tq->cond, &tq->mutex);
	if (rc)
		goto out;
	if (list_empty(&tq->q))
		goto out;

pop:
	ent = list_entry(tq->q.next, struct tq_ent, q_node);
	rval = ent->data;

	list_del(&ent->q_node);
	free(ent);

out:
	mutex_unlock(&tq->mutex);
	return rval;
}

int thr_info_create(struct thr_info *thr, pthread_attr_t *attr, void *(*start) (void *), void *arg)
{
	return pthread_create(&thr->pth, attr, start, arg);
}

void thr_info_freeze(struct thr_info *thr)
{
	struct tq_ent *ent, *iter;
	struct thread_q *tq;

	if (!thr)
		return;

	tq = thr->q;
	if (!tq)
		return;

	mutex_lock(&tq->mutex);
	tq->frozen = true;
	list_for_each_entry_safe(ent, iter, &tq->q, q_node) {
		list_del(&ent->q_node);
		free(ent);
	}
	mutex_unlock(&tq->mutex);
}

void thr_info_cancel(struct thr_info *thr)
{
	if (!thr)
		return;

	if (PTH(thr) != 0L) {
		pthread_cancel(thr->pth);
		PTH(thr) = 0L;
	}
}

/* Provide a ms based sleep that uses nanosleep to avoid poor usleep accuracy
 * on SMP machines */
void nmsleep(unsigned int msecs)
{
	struct timespec twait, tleft;
	int ret;
	ldiv_t d;

	d = ldiv(msecs, 1000);
	tleft.tv_sec = d.quot;
	tleft.tv_nsec = d.rem * 1000000;
	do {
		twait.tv_sec = tleft.tv_sec;
		twait.tv_nsec = tleft.tv_nsec;
		ret = nanosleep(&twait, &tleft);
	} while (ret == -1 && errno == EINTR);
}

/* Returns the microseconds difference between end and start times as a double */
double us_tdiff(struct timeval *end, struct timeval *start)
{
	return end->tv_sec * 1000000 + end->tv_usec - start->tv_sec * 1000000 - start->tv_usec;
}

/* Returns the seconds difference between end and start times as a double */
double tdiff(struct timeval *end, struct timeval *start)
{
	return end->tv_sec - start->tv_sec + (end->tv_usec - start->tv_usec) / 1000000.0;
}

bool extract_sockaddr(struct pool *pool, char *url)
{
	char *url_begin, *url_end, *port_start;
	char *url_address, *port;
	struct addrinfo hints, *res;
	size_t url_len, port_len = 0;

	url_begin = strstr(url, "//");
	if (!url_begin)
		url_begin = url;
	else
		url_begin += 2;
	url_end = strstr(url_begin, ":");
	if (url_end) {
		url_len = url_end - url_begin;
		port_len = strlen(url_begin) - url_len - 1;
		if (port_len < 1)
			return false;
		port_start = url_end + 1;
	} else
		url_len = strlen(url_begin);

	if (url_len < 1)
		return false;

	url_address = alloca(url_len + 1);
	sprintf(url_address, "%.*s", url_len, url_begin);

	if (port_len) {
		port = alloca(port_len + 1);
		sprintf(port, "%.*s", port_len, port_start);
	} else {
		port = alloca(4);
		strcpy(port, "80");
	}

	memset(&hints, 0, sizeof(struct addrinfo));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;

	if (getaddrinfo(url_address, port, &hints, &res)) {
		applog(LOG_DEBUG, "Failed to extract sock addr");
		return false;
	}

	pool->server = (struct sockaddr_in *)res->ai_addr;
	return true;
}