Merge tag 'upstream/0.8.1'

Upstream version 0.8.1

9 files changed, 178 insertions, 270 deletions

diff --git a/README.md b/README.md
index 637f639..e0167f1 100644
--- a/README.md
+++ b/README.md
@@ -12,13 +12,26 @@ See the man page for an in-depth description of operation and configuration.
 
 ### Where to obtain
 
-Apart from debian/ubuntu packages (apt-cache search wavemon) and slackbuild
-scripts for wavemon on slackbuilds.org, this repository contains the full
-source code.
+Apart from debian/ubuntu packages (`apt-cache search wavemon`) and [slackbuild  scripts for wavemon](https://slackbuilds.org/result/?search=wavemon&sv=), this repository contains the full source code.
+
+Please check [this page](#) for updates and for further information.
 
-Please check this page for updates and for further information.
 wavemon is distributed under the [GPLv3](http://www.gnu.org/licenses/gpl-3.0.en.html), refer to the file `COPYING`.
 
+### Dependencies
+
+wavemon requires a Linux Kernel with wireless extensions enabled. If your Kernel setup uses `CONFIG_CFG80211`, make sure that the config option `CONFIG_CFG80211_WEXT` is set.
+
+In addition, minimally the following are required:
+* Netlink `libnl` at least version 3.2,
+* including the Generic Netlink support (`libnl-genl`),
+* ncurses development files (`libncurses5-dev`),
+* the `pkg-config` package.
+
+On Debian/Ubuntu, this can be done using
+```bash
+	apt-get -y install pkg-config libncurses5-dev libnl-3-dev libnl-genl-3-dev
+```
 
 ## How to build
 
@@ -31,12 +44,6 @@ wavemon uses `autoconf`, so that in most cases you can simply run
 to build and install the package. Type 'make uninstall' if not happy.
 Refer to the file `INSTALL` for generic installation instructions.
 
-**Dependencies**: at least version 3.2 of `libnl`, including the Generic Netlink support (`libnl-genl`).
-On Debian/Ubuntu, this can be done using
-```bash
-	apt-get -y install libnl-3-dev libnl-genl-3-dev
-```
-
 To grant users access to restricted networking operations (scan operations), use additionally
 ```
 	sudo make install-suid-root
@@ -45,8 +52,7 @@ If you have changed some of the autoconf files or use a git version, run
 ```
 	./config/bootstrap
 ```
-(requires a recent installation of `autotools`).
-
+(This requires a recent installation of `autotools`.)
 
 ## Bugs?
 
diff --git a/conf.c b/conf.c
index 27c11dc..294564b 100644
--- a/conf.c
+++ b/conf.c
@@ -20,6 +20,7 @@
 #include "wavemon.h"
 #include <pwd.h>
 #include <sys/types.h>
+#include <netlink/version.h>
 
 /* GLOBALS */
 #define MAX_IFLIST_ENTRIES 64
@@ -94,7 +95,7 @@ void conf_get_interface_list(void)
 	}
 	iw_get_interface_list(if_list, MAX_IFLIST_ENTRIES);
 	if (!if_list[0])
-		err_quit("no supported wireless interfaces found!");
+		err_quit("no supported wireless interfaces found! Check manpage for help.");
 
 	conf.if_idx = 0;
 	if (old_if) {
@@ -529,10 +530,7 @@ static void init_conf_items(void)
 void getconf(int argc, char *argv[])
 {
 	int arg, help = 0, version = 0;
-
-	conf_get_interface_list();
-	init_conf_items();
-	read_cf();
+	const char *iface = NULL;
 
 	while ((arg = getopt(argc, argv, "ghi:v")) >= 0) {
 		switch (arg) {
@@ -543,10 +541,7 @@ void getconf(int argc, char *argv[])
 			help++;
 			break;
 		case 'i':
-			conf.if_idx = argv_find(if_list, optarg);
-			if (conf.if_idx < 0)
-				err_quit("no wireless extensions found on '%s'",
-					 optarg);
+			iface = optarg;
 			break;
 		case 'v':
 			version++;
@@ -557,8 +552,7 @@ void getconf(int argc, char *argv[])
 	}
 
 	if (version) {
-		printf("wavemon %s", PACKAGE_VERSION);
-		printf(" with %s.\n", curses_version());
+		printf("wavemon %s\n", PACKAGE_VERSION);
 		printf("Distributed under the terms of the GPLv3.\n%s", help ? "\n" : "");
 	}
 	if (help) {
@@ -566,9 +560,21 @@ void getconf(int argc, char *argv[])
 		printf("  -g            Ensure screen is sufficiently dimensioned\n");
 		printf("  -h            This help screen\n");
 		printf("  -i <ifname>   Use specified network interface (default: auto)\n");
-		printf("  -v            Print version number\n");
+		printf("  -v            Print version details\n");
 	}
 
-	if (version || help)
+	if (version || help) {
 		exit(EXIT_SUCCESS);
+	}
+
+	/* Actual initialization. */
+	conf_get_interface_list();
+	init_conf_items();
+	read_cf();
+
+	if (iface) {
+		conf.if_idx = argv_find(if_list, iface);
+		if (conf.if_idx < 0)
+			err_quit("%s is not a usable wireless interface", iface);
+	}
 }
diff --git a/info_scr.c b/info_scr.c
index 6a50b43..55a3bbc 100644
--- a/info_scr.c
+++ b/info_scr.c
@@ -22,29 +22,45 @@
 
 /* GLOBALS */
 static WINDOW *w_levels, *w_stats, *w_if, *w_info, *w_net;
-static struct timer dyn_updates;
-struct iw_range	range;
-static struct iw_nl80211_linkstat ls;
-
-void sampling_init(void (*sampling_handler)(int))
+static pthread_t sampling_thread;
+static time_t last_update;
+// Global linkstat data, populated by sampling thread.
+static struct {
+	bool              run;	 // enable/disable sampling
+	pthread_mutex_t   mutex; // producer/consumer lock for @data
+	struct iw_nl80211_linkstat data;
+} linkstat;
+
+/** Sampling pthread shared by info and histogram screen. */
+static void *sampling_loop(void *arg)
 {
-	struct itimerval i;
-	div_t d = div(conf.stat_iv, 1000);	/* conf.stat_iv in msec */
+	sigset_t blockmask;
 
-	xsignal(SIGALRM, SIG_IGN);
-	iw_getinf_range(conf_ifname(), &range);
-	i.it_interval.tv_sec  = i.it_value.tv_sec  = d.quot;
-	i.it_interval.tv_usec = i.it_value.tv_usec = d.rem * 1000;
-	xsignal(SIGALRM, sampling_handler);
+	/* See comment in scan_scr.c for rationale. */
+	sigemptyset(&blockmask);
+	sigaddset(&blockmask, SIGWINCH);
+	pthread_sigmask(SIG_BLOCK, &blockmask, NULL);
+
+	do {
+		pthread_mutex_lock(&linkstat.mutex);
+		iw_nl80211_get_linkstat(&linkstat.data);
+		pthread_mutex_unlock(&linkstat.mutex);
 
-	(*sampling_handler)(0);
-	setitimer(ITIMER_REAL, &i, NULL);
+		iw_cache_update(&linkstat.data);
+	} while (linkstat.run && usleep(conf.stat_iv * 1000) == 0);
+	return NULL;
 }
 
-void sampling_do_poll(void)
+void sampling_init(void)
 {
-	iw_nl80211_get_linkstat(&ls);
-	iw_cache_update(&ls);
+	linkstat.run = true;
+	pthread_create(&sampling_thread, NULL, sampling_loop, NULL);
+}
+
+void sampling_stop(void)
+{
+	linkstat.run = false;
+	pthread_join(sampling_thread, NULL);
 }
 
 static void display_levels(void)
@@ -59,21 +75,23 @@ static void display_levels(void)
 	     lvlscale[2] = { -40, -20};
 	char tmp[0x100];
 	int line;
-	bool noise_data_valid = iw_nl80211_have_survey_data(&ls);
-	int sig_qual = -1;
-	int sig_qual_max;
-	int sig_level = ls.signal_avg ?: ls.signal;
+	bool noise_data_valid;
+	int sig_qual = -1, sig_qual_max, sig_level;
+
+
+	noise_data_valid = iw_nl80211_have_survey_data(&linkstat.data);
+	sig_level = linkstat.data.signal_avg ?: linkstat.data.signal;
 
 	/* See comments in iw_cache_update */
 	if (sig_level == 0)
-		sig_level = ls.bss_signal;
+		sig_level = linkstat.data.bss_signal;
 
 	for (line = 1; line <= WH_LEVEL; line++)
 		mvwclrtoborder(w_levels, line, 1);
 
-	if (ls.bss_signal_qual) {
+	if (linkstat.data.bss_signal_qual) {
 		/* BSS_SIGNAL_UNSPEC is scaled 0..100 */
-		sig_qual     = ls.bss_signal_qual;
+		sig_qual     = linkstat.data.bss_signal_qual;
 		sig_qual_max = 100;
 	} else if (sig_level) {
 		if (sig_level < -110)
@@ -136,7 +154,7 @@ static void display_levels(void)
 	line++;
 
 	if (noise_data_valid) {
-		noise = ewma(noise, ls.survey.noise, conf.meter_decay / 100.0);
+		noise = ewma(noise, linkstat.data.survey.noise, conf.meter_decay / 100.0);
 
 		mvwaddstr(w_levels, line++, 1, "noise level:  ");
 		sprintf(tmp, "%.0f dBm (%s)", noise, dbm2units(noise));
@@ -147,7 +165,7 @@ static void display_levels(void)
 	}
 
 	if (noise_data_valid && sig_level) {
-		ssnr = ewma(ssnr, sig_level - ls.survey.noise,
+		ssnr = ewma(ssnr, sig_level - linkstat.data.survey.noise,
 				  conf.meter_decay / 100.0);
 
 		mvwaddstr(w_levels, line++, 1, "SNR:           ");
@@ -161,42 +179,39 @@ done_levels:
 
 static void display_stats(void)
 {
-	struct if_stat nstat;
 	char tmp[0x100];
 
-	if_getstat(conf_ifname(), &nstat);
-
 	/*
 	 * Interface RX stats
 	 */
 	mvwaddstr(w_stats, 1, 1, "RX: ");
 
-	if (ls.rx_packets) {
-		sprintf(tmp, "%'u (%s)",  ls.rx_packets,
-			byte_units(ls.rx_bytes));
+	if (linkstat.data.rx_packets) {
+		sprintf(tmp, "%'u (%s)",  linkstat.data.rx_packets,
+			byte_units(linkstat.data.rx_bytes));
 		waddstr_b(w_stats, tmp);
 	} else {
 		waddstr(w_stats, "n/a");
 	}
 
-	if (iw_nl80211_have_survey_data(&ls)) {
-		if (ls.rx_bitrate[0]) {
+	if (iw_nl80211_have_survey_data(&linkstat.data)) {
+		if (linkstat.data.rx_bitrate[0]) {
 			waddstr(w_stats, ", rate: ");
-			waddstr_b(w_stats, ls.rx_bitrate);
+			waddstr_b(w_stats, linkstat.data.rx_bitrate);
 		}
 
-		if (ls.expected_thru) {
-			if (ls.expected_thru >= 1024)
-				sprintf(tmp, " (exp: %.1f MB/s)",  ls.expected_thru/1024.0);
+		if (linkstat.data.expected_thru) {
+			if (linkstat.data.expected_thru >= 1024)
+				sprintf(tmp, " (expected: %.1f MB/s)",  linkstat.data.expected_thru/1024.0);
 			else
-				sprintf(tmp, " (exp: %u kB/s)",  ls.expected_thru);
+				sprintf(tmp, " (expected: %u kB/s)",  linkstat.data.expected_thru);
 			waddstr(w_stats, tmp);
 		}
 	}
 
-	if (ls.rx_drop_misc) {
+	if (linkstat.data.rx_drop_misc) {
 		waddstr(w_stats, ", drop: ");
-		sprintf(tmp, "%'llu", (unsigned long long)ls.rx_drop_misc);
+		sprintf(tmp, "%'llu", (unsigned long long)linkstat.data.rx_drop_misc);
 		waddstr_b(w_stats, tmp);
 	}
 
@@ -207,28 +222,28 @@ static void display_stats(void)
 	 */
 	mvwaddstr(w_stats, 2, 1, "TX: ");
 
-	if (ls.tx_packets) {
-		sprintf(tmp, "%'u (%s)",  ls.tx_packets,
-			byte_units(ls.tx_bytes));
+	if (linkstat.data.tx_packets) {
+		sprintf(tmp, "%'u (%s)",  linkstat.data.tx_packets,
+			byte_units(linkstat.data.tx_bytes));
 		waddstr_b(w_stats, tmp);
 	} else {
 		waddstr(w_stats, "n/a");
 	}
 
-	if (iw_nl80211_have_survey_data(&ls) && ls.tx_bitrate[0]) {
+	if (iw_nl80211_have_survey_data(&linkstat.data) && linkstat.data.tx_bitrate[0]) {
 		waddstr(w_stats, ", rate: ");
-		waddstr_b(w_stats, ls.tx_bitrate);
+		waddstr_b(w_stats, linkstat.data.tx_bitrate);
 	}
 
-	if (ls.tx_retries) {
+	if (linkstat.data.tx_retries) {
 		waddstr(w_stats, ", retries: ");
-		sprintf(tmp, "%'u", ls.tx_retries);
+		sprintf(tmp, "%'u", linkstat.data.tx_retries);
 		waddstr_b(w_stats, tmp);
 	}
 
-	if (ls.tx_failed) {
+	if (linkstat.data.tx_failed) {
 		waddstr(w_stats, ", failed: ");
-		sprintf(tmp, "%'u", ls.tx_failed);
+		sprintf(tmp, "%'u", linkstat.data.tx_failed);
 		waddstr_b(w_stats, tmp);
 	}
 	wclrtoborder(w_stats);
@@ -238,11 +253,13 @@ static void display_stats(void)
 static void display_info(WINDOW *w_if, WINDOW *w_info)
 {
 	struct iw_dyn_info info;
+	struct iw_range	range;
 	struct iw_nl80211_ifstat ifs;
 	struct iw_nl80211_reg ir;
 	char tmp[0x100];
 	int i;
 
+	iw_getinf_range(conf_ifname(), &range);
 	dyn_info_get(&info, conf_ifname(), &range);
 	iw_nl80211_getifstat(&ifs);
 	iw_nl80211_getreg(&ir);
@@ -252,10 +269,7 @@ static void display_info(WINDOW *w_if, WINDOW *w_info)
 	 */
 	wmove(w_if, 1, 1);
 	waddstr_b(w_if, conf_ifname());
-	if (range.enc_capa & IW_WPA_MASK)
-		sprintf(tmp, " (%s, %s)", info.name, format_wpa(&range));
-	else
-		sprintf(tmp, " (%s)", info.name);
+	sprintf(tmp, " (%s)", info.name);
 	waddstr(w_if, tmp);
 
 	/* PHY */
@@ -288,10 +302,10 @@ static void display_info(WINDOW *w_if, WINDOW *w_info)
 	waddstr(w_info, "mode: ");
 	waddstr_b(w_info, iftype_name(ifs.iftype));
 
-	if (!ether_addr_is_zero(&ls.bssid)) {
+	if (!ether_addr_is_zero(&linkstat.data.bssid)) {
 		waddstr_b(w_info, ", ");
 
-		switch (ls.status) {
+		switch (linkstat.data.status) {
 		case NL80211_BSS_STATUS_ASSOCIATED:
 			waddstr(w_info, "connected to: ");
 			break;
@@ -304,15 +318,15 @@ static void display_info(WINDOW *w_if, WINDOW *w_info)
 		default:
 			waddstr(w_info, "station: ");
 		}
-		waddstr_b(w_info, ether_lookup(&ls.bssid));
+		waddstr_b(w_info, ether_lookup(&linkstat.data.bssid));
 
-		if (ls.status == NL80211_BSS_STATUS_ASSOCIATED) {
+		if (linkstat.data.status == NL80211_BSS_STATUS_ASSOCIATED) {
 			waddstr_b(w_info, ",");
 			waddstr(w_info, " time: ");
-			waddstr_b(w_info, pretty_time(ls.connected_time));
+			waddstr_b(w_info, pretty_time(linkstat.data.connected_time));
 
 			waddstr(w_info, ", inactive: ");
-			sprintf(tmp, "%.1fs", (float)ls.inactive_time/1e3);
+			sprintf(tmp, "%.1fs", (float)linkstat.data.inactive_time/1e3);
 			waddstr_b(w_info, tmp);
 		}
 	}
@@ -326,8 +340,8 @@ static void display_info(WINDOW *w_if, WINDOW *w_info)
 		waddstr_b(w_info, tmp);
 
 		/* The following condition should in theory never happen */
-		if (ls.survey.freq && ls.survey.freq != ifs.freq) {
-			sprintf(tmp, " [survey freq: %d MHz]", ls.survey.freq);
+		if (linkstat.data.survey.freq && linkstat.data.survey.freq != ifs.freq) {
+			sprintf(tmp, " [survey freq: %d MHz]", linkstat.data.survey.freq);
 			waddstr(w_info, tmp);
 		}
 
@@ -353,9 +367,9 @@ static void display_info(WINDOW *w_if, WINDOW *w_info)
 			sprintf(tmp, " (%s)", channel_type_name(ifs.chan_type));
 			waddstr(w_info, tmp);
 		}
-	} else if (iw_nl80211_have_survey_data(&ls)) {
+	} else if (iw_nl80211_have_survey_data(&linkstat.data)) {
 		waddstr(w_info, "freq: ");
-		sprintf(tmp, "%d MHz", ls.survey.freq);
+		sprintf(tmp, "%d MHz", linkstat.data.survey.freq);
 		waddstr_b(w_info, tmp);
 	} else {
 		waddstr(w_info, "frequency/channel: n/a");
@@ -364,87 +378,87 @@ static void display_info(WINDOW *w_if, WINDOW *w_info)
 
 	/* Channel data */
 	wmove(w_info, 3, 1);
-	if (iw_nl80211_have_survey_data(&ls)) {
+	if (iw_nl80211_have_survey_data(&linkstat.data)) {
 		waddstr(w_info, "channel ");
 		waddstr(w_info, "active: ");
-		waddstr_b(w_info, pretty_time_ms(ls.survey.time.active));
+		waddstr_b(w_info, pretty_time_ms(linkstat.data.survey.time.active));
 
 		waddstr(w_info, ", busy: ");
-		waddstr_b(w_info, pretty_time_ms(ls.survey.time.busy));
+		waddstr_b(w_info, pretty_time_ms(linkstat.data.survey.time.busy));
 
-		if (ls.survey.time.ext_busy) {
+		if (linkstat.data.survey.time.ext_busy) {
 			waddstr(w_info, ", ext-busy: ");
-			waddstr_b(w_info, pretty_time_ms(ls.survey.time.ext_busy));
+			waddstr_b(w_info, pretty_time_ms(linkstat.data.survey.time.ext_busy));
 		}
 
 		waddstr(w_info, ", rx: ");
-		waddstr_b(w_info, pretty_time_ms(ls.survey.time.rx));
+		waddstr_b(w_info, pretty_time_ms(linkstat.data.survey.time.rx));
 
 		waddstr(w_info, ", tx: ");
-		waddstr_b(w_info, pretty_time_ms(ls.survey.time.tx));
+		waddstr_b(w_info, pretty_time_ms(linkstat.data.survey.time.tx));
 
-		if (ls.survey.time.scan) {
+		if (linkstat.data.survey.time.scan) {
 			waddstr(w_info, ", scan: ");
-			waddstr_b(w_info, pretty_time_ms(ls.survey.time.scan));
+			waddstr_b(w_info, pretty_time_ms(linkstat.data.survey.time.scan));
 		}
-	} else if (ls.tx_bitrate[0] && ls.rx_bitrate[0]) {
+	} else if (linkstat.data.tx_bitrate[0] && linkstat.data.rx_bitrate[0]) {
 		waddstr(w_info, "rx rate: ");
-		waddstr_b(w_info, ls.rx_bitrate);
+		waddstr_b(w_info, linkstat.data.rx_bitrate);
 
-		if (ls.expected_thru) {
-			if (ls.expected_thru >= 1024)
-				sprintf(tmp, " (exp: %.1f MB/s)",  ls.expected_thru/1024.0);
+		if (linkstat.data.expected_thru) {
+			if (linkstat.data.expected_thru >= 1024)
+				sprintf(tmp, " (exp: %.1f MB/s)",  linkstat.data.expected_thru/1024.0);
 			else
-				sprintf(tmp, " (exp: %u kB/s)",  ls.expected_thru);
+				sprintf(tmp, " (exp: %u kB/s)",  linkstat.data.expected_thru);
 			waddstr(w_info, tmp);
 		}
 		waddstr(w_info, ", tx rate: ");
-		waddstr_b(w_info, ls.tx_bitrate);
+		waddstr_b(w_info, linkstat.data.tx_bitrate);
 	}
 
 	/* Beacons */
 	wmove(w_info, 4, 1);
 
-	if (ls.beacons) {
+	if (linkstat.data.beacons) {
 		waddstr(w_info, "beacons: ");
-		sprintf(tmp, "%'llu", (unsigned long long)ls.beacons);
+		sprintf(tmp, "%'llu", (unsigned long long)linkstat.data.beacons);
 		waddstr_b(w_info, tmp);
 
-		if (ls.beacon_loss) {
+		if (linkstat.data.beacon_loss) {
 			waddstr(w_info, ", lost: ");
-			sprintf(tmp, "%'u", ls.beacon_loss);
+			sprintf(tmp, "%'u", linkstat.data.beacon_loss);
 			waddstr_b(w_info, tmp);
 		}
 		waddstr(w_info, ", avg sig: ");
-		sprintf(tmp, "%d dBm", (int8_t)ls.beacon_avg_sig);
+		sprintf(tmp, "%d dBm", (int8_t)linkstat.data.beacon_avg_sig);
 		waddstr_b(w_info, tmp);
 
 		waddstr(w_info, ", interval: ");
-		sprintf(tmp, "%.1fs", (ls.beacon_int * 1024.0)/1e6);
+		sprintf(tmp, "%.1fs", (linkstat.data.beacon_int * 1024.0)/1e6);
 		waddstr_b(w_info, tmp);
 
 		waddstr(w_info, ", DTIM: ");
-		sprintf(tmp, "%u", ls.dtim_period);
+		sprintf(tmp, "%u", linkstat.data.dtim_period);
 		waddstr_b(w_info, tmp);
 	} else {
 		waddstr(w_info, "station flags:");
-		if (ls.cts_protection)
+		if (linkstat.data.cts_protection)
 			waddstr_b(w_info, " CTS");
-		if (ls.wme)
+		if (linkstat.data.wme)
 			waddstr_b(w_info, " WME");
-		if (ls.tdls)
+		if (linkstat.data.tdls)
 			waddstr_b(w_info, " TDLS");
-		if (ls.mfp)
+		if (linkstat.data.mfp)
 			waddstr_b(w_info, " MFP");
-		if (!(ls.cts_protection | ls.wme | ls.tdls | ls.mfp))
+		if (!(linkstat.data.cts_protection | linkstat.data.wme | linkstat.data.tdls | linkstat.data.mfp))
 			waddstr_b(w_info, " (none)");
 		waddstr(w_info, ", preamble:");
-		if (ls.long_preamble)
+		if (linkstat.data.long_preamble)
 			waddstr_b(w_info, " long");
 		else
 			waddstr_b(w_info, " short");
 		waddstr(w_info, ", slot:");
-		if (ls.short_slot_time)
+		if (linkstat.data.short_slot_time)
 			waddstr_b(w_info, " short");
 		else
 			waddstr_b(w_info, " long");
@@ -657,6 +671,7 @@ static void display_netinfo(WINDOW *w_net)
 			waddstr_b(w_net, inet_ntoa(info.bcast));
 		}
 	}
+	wclrtoborder(w_net);
 
 	/* 802.11 MTU may be greater than Ethernet MTU (1500) */
 	if (info.mtu && info.mtu != ETH_DATA_LEN) {
@@ -668,13 +683,6 @@ static void display_netinfo(WINDOW *w_net)
 	wrefresh(w_net);
 }
 
-static void redraw_stat_levels(int signum)
-{
-	sampling_do_poll();
-	display_levels();
-	display_stats();
-}
-
 void scr_info_init(void)
 {
 	int line = 0;
@@ -692,18 +700,23 @@ void scr_info_init(void)
 	else
 		w_net = newwin_title(line, WH_NET_MAX, "Network", false);
 
-	display_info(w_if, w_info);
-	display_netinfo(w_net);
-	start_timer(&dyn_updates, conf.info_iv * 1000000);
-	sampling_init(redraw_stat_levels);
+	sampling_init();
 }
 
 int scr_info_loop(WINDOW *w_menu)
 {
-	if (end_timer(&dyn_updates)) {
+	time_t now = time(NULL);
+
+	if (!pthread_mutex_trylock(&linkstat.mutex)) {
+		display_levels();
+		display_stats();
+		pthread_mutex_unlock(&linkstat.mutex);
+	}
+
+	if (now - last_update >= conf.info_iv) {
+		last_update = now;
 		display_info(w_if, w_info);
 		display_netinfo(w_net);
-		start_timer(&dyn_updates, conf.info_iv * 1000000);
 	}
 	return wgetch(w_menu);
 }
diff --git a/iw_if.c b/iw_if.c
index 77fc5c2..ca7d3c5 100644
--- a/iw_if.c
+++ b/iw_if.c
@@ -148,35 +148,6 @@ void iw_get_interface_list(char** if_list, size_t max_entries)
 	fclose(fp);
 }
 
-void if_getstat(const char *ifname, struct if_stat *stat)
-{
-	char line[0x100];
-	unsigned long long d;
-	char *lp;
-	size_t l = strlen(ifname);
-	const char path[] = "/proc/net/dev";
-	FILE *fp = fopen(path, "r");
-
-	if (fp == NULL)
-		err_sys("can not open %s", path);
-	/*
-	 * Inter-|   Receive                                                | Transmit
-	 *  face |bytes    packets errs drop fifo frame compressed multicast|bytes packets
-	 */
-	while (fgets(line, sizeof(line), fp)) {
-		lp = line + strspn(line, " ");
-		if (!strncmp(lp, ifname, l) && lp[l] == ':') {
-			lp += l + 1;
-			lp += strspn(lp, " ");
-
-			sscanf(lp, "%llu %llu %llu %llu %llu %llu %llu %llu %llu %llu",
-				&stat->rx_bytes, &stat->rx_packets, &d, &d, &d, &d, &d, &d,
-				&stat->tx_bytes, &stat->tx_packets);
-		}
-	}
-	fclose(fp);
-}
-
 /**
  * iw_dyn_info_get  -  populate dynamic information
  * @info:   information to populate
@@ -192,7 +163,7 @@ void dyn_info_get(struct iw_dyn_info *info,
 	if (skfd < 0)
 		err_sys("%s: can not open socket", __func__);
 
-	memset(info, 0, sizeof(struct iw_dyn_info));
+	memset(info, 0, sizeof(*info));
 	strncpy(iwr.ifr_name, ifname, IFNAMSIZ);
 
 	if (ioctl(skfd, SIOCGIWNAME, &iwr) < 0)
diff --git a/iw_if.h b/iw_if.h
index cc9e886..846e9f9 100644
--- a/iw_if.h
+++ b/iw_if.h
@@ -181,18 +181,6 @@ extern void dyn_info_get(struct iw_dyn_info *info,
 extern void dyn_info_cleanup(struct iw_dyn_info *info);
 
 
-/**
- * struct if_stat  -  Packet/byte counts for interfaces
- */
-struct if_stat {
-	unsigned long long	rx_packets,
-				tx_packets;
-	unsigned long long	rx_bytes,
-				tx_bytes;
-};
-
-extern void if_getstat(const char *ifname, struct if_stat *stat);
-
 /*
  *	 Structs to communicate WiFi statistics
  */
@@ -206,11 +194,10 @@ struct iw_levelstat {
 extern void iw_getinf_range(const char *ifname, struct iw_range *range);
 
 /*
- * 	Periodic sampling of wireless statistics via timer alarm
+ * 	Periodic sampling of wireless statistics
  */
-extern void sampling_init(void (*sampling_handler)(int));
-extern void sampling_do_poll(void);
-static inline void sampling_stop(void)	{ alarm(0); }
+extern void sampling_init(void);
+extern void sampling_stop(void);
 
 /*
  *	Organization of scan results
@@ -457,31 +444,6 @@ static inline char *format_key(const struct iw_key *const iwk)
 	return buf;
 }
 
-/* Human-readable representation of IW_ENC_CAPA_ types */
-static inline const char *format_enc_capab(const uint32_t capa, const char *sep)
-{
-	static char buf[32];
-	size_t len = 0, max = sizeof(buf);
-
-	if (capa & IW_ENC_CAPA_WPA)
-		len = snprintf(buf, max, "WPA");
-	if (capa & IW_ENC_CAPA_WPA2)
-		len += snprintf(buf + len, max - len, "%sWPA2", len ? sep : "");
-	if (capa & IW_ENC_CAPA_CIPHER_TKIP)
-		len += snprintf(buf + len, max - len, "%sTKIP", len ? sep : "");
-	if (capa & IW_ENC_CAPA_CIPHER_CCMP)
-		len += snprintf(buf + len, max - len, "%sCCMP", len ? sep : "");
-	buf[len] = '\0';
-	return buf;
-}
-
-/* Display only the supported WPA type */
-#define IW_WPA_MASK	(IW_ENC_CAPA_WPA|IW_ENC_CAPA_WPA2)
-static inline const char *format_wpa(struct iw_range *ir)
-{
-	return format_enc_capab(ir->enc_capa & IW_WPA_MASK, "/");
-}
-
 static inline char *format_retry(const struct iw_param *retry,
 				 const struct iw_range *range)
 {
diff --git a/lhist_scr.c b/lhist_scr.c
index 2595b45..55d5d6b 100644
--- a/lhist_scr.c
+++ b/lhist_scr.c
@@ -317,18 +317,6 @@ static void display_key(WINDOW *w_key)
 	wrefresh(w_key);
 }
 
-static void redraw_lhist(int signum)
-{
-	static int vcount = 1;
-
-	sampling_do_poll();
-	if (!--vcount) {
-		vcount = conf.slotsize;
-		display_lhist();
-		display_key(w_key);
-	}
-}
-
 void scr_lhist_init(void)
 {
 	w_lhist = newwin_title(0, HIST_WIN_HEIGHT, "Level histogram", true);
@@ -337,13 +325,20 @@ void scr_lhist_init(void)
 	init_extrema(&e_signal);
 	init_extrema(&e_noise);
 	init_extrema(&e_snr);
-	sampling_init(redraw_lhist);
+	sampling_init();
 
 	display_key(w_key);
 }
 
 int scr_lhist_loop(WINDOW *w_menu)
 {
+	static int vcount = 1;
+
+	if (!--vcount) {
+		vcount = conf.slotsize;
+		display_lhist();
+		display_key(w_key);
+	}
 	return wgetch(w_menu);
 }
 
diff --git a/timer.c b/timer.c
deleted file mode 100644
index cb6500c..0000000
--- a/timer.c
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * wavemon - a wireless network monitoring aplication
- *
- * Copyright (c) 2001-2002 Jan Morgenstern <jan@jm-music.de>
- *
- * wavemon 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 2, or (at your option) any later
- * version.
- *
- * wavemon is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
- * details.
- *
- * You should have received a copy of the GNU General Public License along
- * with wavemon; see the file COPYING.  If not, write to the Free Software
- * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- */
-#include "wavemon.h"
-
-static unsigned long get_usecs(void)
-{
-	struct timeval tv;
-	struct timezone tz;
-
-	gettimeofday(&tv, &tz);
-
-	return tv.tv_sec * 1000000 + tv.tv_usec;
-}
-
-void start_timer(struct timer *t, unsigned long duration)
-{
-	t->stime    = get_usecs();
-	t->duration = duration;
-}
-
-bool end_timer(struct timer *t)
-{
-	return get_usecs() >= t->stime + t->duration;
-}
diff --git a/wavemon.1 b/wavemon.1
index ccfba7d..b5a9e58 100644
--- a/wavemon.1
+++ b/wavemon.1
@@ -1,4 +1,4 @@
-.TH wavemon 1 "January 2015" Linux "User Manuals"
+.TH wavemon 1 "September 2016" Linux "User Manuals"
 .SH NAME
 wavemon \- a wireless network monitor
 .SH SYNOPSIS
@@ -121,6 +121,12 @@ properly.
 print help and exit.
 .IP "\fB\-v\fR"
 print version information and exit.
+.SH Troubleshooting
+wavemon will exit with \fB'no supported wireless interfaces found'\fR if no usable wireless interfaces
+were detected. Check if your wireless interfaces is otherwise usable, using e.g. \fIiw\fR, \fIiwconfig\fR,
+or similar tools. The interface should appear in /proc/net/dev and, if wireless extensions are supported,
+also in /proc/net/wireless. If the interface does not appear, causes can be a missing (or not loaded)
+kernel module, or missing firmware, which some cards need to operate.
 
 .SH "ENVIRONMENT VARIABLES"
 .IP "LC_NUMERIC"
@@ -131,7 +137,7 @@ The local per-user configuration file.
 .SH "AUTHOR"
 Written by Jan Morgenstern <jan@jm-music.de>.
 .SH "REPORTING BUGS"
-Send bug reports and/or suggestions to Gerrit Renker <gerrit@erg.abdn.ac.uk>.
+Open an issue on \fIhttps://github.com/uoaerg/wavemon/issues\fR.
 .SH "COPYRIGHT"
 This is free software with ABSOLUTELY NO WARRANTY. See file COPYING for details.
 .SH "SEE ALSO"
diff --git a/wavemon.h b/wavemon.h
index e7584f7..ee0cff4 100644
--- a/wavemon.h
+++ b/wavemon.h
@@ -18,6 +18,7 @@
  * with wavemon; see the file COPYING.  If not, write to the Free Software
  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -284,17 +285,6 @@ extern void conf_get_interface_list(void);
 extern void iw_get_interface_list(char** if_list, size_t max_entries);
 
 /*
- *	Timers
- */
-struct timer {
-	unsigned long long	stime;
-	unsigned long		duration;
-};
-
-extern void start_timer(struct timer *t, unsigned long d);
-extern bool end_timer(struct timer *t);
-
-/*
  *	Error handling
  */
 extern bool has_net_admin_capability(void);