Rewrite the main loop to use a timer.

XXX not finished yet, lots of debug information and bugs left.

Makefile

@@ -5,10 +5,12 @@ SRCS= echoc.c
 
 OBJS= $(SRCS:%.c=%.o)
 
+LIBS=	-lrt
+
 all: $(PROG)
 
 $(PROG): $(OBJS)
-	$(CC) -o $@ $(OBJS)
+	$(CC) -o $@ $(OBJS) $(LIBS)
 
 .c.o:
 	$(CC) -c $(CFLAGS) -o $@ $<

echoc.c

@@ -14,6 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 #include <sys/types.h>
+#include <sys/ioctl.h>
 #include <sys/socket.h>
 #include <sys/time.h>
 
@@ -22,6 +23,7 @@
 #include <netdb.h>
 #include <poll.h>
 #include <signal.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -33,6 +35,8 @@ int verbose = 0;
 struct sockaddr *server;
 socklen_t serverlen;
 unsigned int seq = 0;
+int disconnected;
+struct timespec sent;
 
 #define THRESHOLD 10
 
@@ -42,6 +46,50 @@ usage(void)
 	errx(2, "usage: echoc [-v] server");
 }
 
+static void
+send_packet(bool timestamp)
+{
+	if (sendto(sock, &seq, sizeof(seq), 0, server,
+		serverlen) != sizeof(seq)) {
+		if (verbose)
+			warn("sendto");
+	}
+	if (timestamp) 
+		clock_gettime(CLOCK_REALTIME, &sent);
+	if (verbose > 1) 
+		printf("sent %d\n", seq);
+	seq++;
+}
+
+static void
+timer_handler(int unused)
+{
+	send_packet(!disconnected);
+}
+
+static void
+timespec_substract(struct timespec *result,
+    const struct timespec *x, const struct timespec *y)
+{
+	struct timespec yy;
+
+	memcpy(&yy, y, sizeof(struct timespec));
+
+	/* Carry */
+	if (x->tv_nsec < y->tv_nsec) {
+		long sec = (y->tv_nsec - x->tv_nsec) / 1000000000 + 1;
+		yy.tv_nsec -= 1000000000 * sec;
+		yy.tv_sec += sec;
+	}
+	if (x->tv_nsec - y->tv_nsec > 1000000000) {
+		int sec = (x->tv_nsec - y->tv_nsec) / 1000000000;
+		yy.tv_nsec += 1000000000 * sec;
+		yy.tv_sec -= sec;
+	}
+
+	result->tv_sec = x->tv_sec - yy.tv_sec;
+	result->tv_nsec = x->tv_nsec - yy.tv_nsec;
+}
 
 int
 main(int argc, char *argv[])
@@ -51,19 +99,23 @@ main(int argc, char *argv[])
 	struct sockaddr_storage client;
 	struct addrinfo hints, *res, *res0;
 	struct timeval tv;
+	struct itimerspec ts;
+	struct sigevent se;
+	struct sigaction sa;
 	struct tm *tm;
 	struct pollfd pfd[1];
 	socklen_t addrlen;
+	timer_t timer;
 	int ch;
 	int nfds, received = 0;
-	int error, dropped, buffer, last;
+	int error, buffer, last;
 	extern int optind;
 
 	setbuf(stdout, NULL);
 	while ((ch = getopt(argc, argv, "v")) != -1) {
 		switch (ch) {
 		case 'v':
-			verbose = 1;
+			verbose++;
 			break;
 		default:
 			usage();
@@ -93,33 +145,75 @@ main(int argc, char *argv[])
 	if (sock == -1)
 		err(1, "socket");
 
-	dropped = 0;
+	disconnected = 1;
 	memset(&client, 0, sizeof(client));
 	gettimeofday(&tv, NULL);
-	while (1) {
-		if (sendto(sock, &seq, sizeof(seq), 0, server,
-			serverlen) != sizeof(seq)) {
-			if (verbose)
-				warn("sendto");
-		}
-		seq++;
 
+	/* create a timer generating SIGALRM */
+	memset(&se, 0, sizeof(struct sigevent));
+	se.sigev_signo = SIGALRM;
+	se.sigev_notify = SIGEV_SIGNAL;
+	timer_create(CLOCK_REALTIME, &se, &timer);
+
+	/* timer values */
+	ts.it_interval.tv_nsec = 100000000; /* 100ms */
+	ts.it_interval.tv_sec = 0;
+	ts.it_value.tv_nsec = 100000000;
+	ts.it_value.tv_sec = 0;
+	timer_settime(timer, 0, &ts, NULL);
+
+	/* set SIGALRM handler  */
+	sa.sa_handler = timer_handler;
+	sigemptyset(&sa.sa_mask);
+	sigaddset(&sa.sa_mask, SIGALRM); /* block SIGALRM during handler */
+	sigaction(SIGALRM, &sa, NULL);
+
+	/* send initial packet */
+	send_packet(true);
+
+	while (1) {
+		struct timespec now, diff;
+
+		while (1) {
 			pfd[0].fd = sock;
 			pfd[0].events = POLLIN;
 			nfds = poll(pfd, 1, 200);
+			clock_gettime(CLOCK_REALTIME, &now);
+			timespec_substract(&diff, &now, &sent);
+			if (nfds > 0)
+				break;
 			if (nfds == -1 && errno != EINTR)
 				warn("poll error");
-		if ((nfds == 0) || (nfds == -1 && errno == EINTR)) {
+			if (verbose > 2) 
-			dropped++;
+				printf("%d %s\n", nfds, strerror(errno));
-			if (dropped == THRESHOLD) {
+			if (verbose > 1) 
-				tm = localtime((time_t *)&tv.tv_sec);
+				printf("wait %ld.%06ld\n", 
+				    (long)diff.tv_sec, diff.tv_nsec/1000);
+			if (diff.tv_sec > 0 || diff.tv_nsec > 200000000) {
+				if (verbose) 
+					printf("timeout %ld.%06ld\n", 
+					    (long)diff.tv_sec, diff.tv_nsec/1000);
+				disconnected++;
+				nfds = 0;
+				break;
+			}
+		}
+		if ((nfds == 0)) {
+			if (verbose > 1) 
+				printf("!! %d packet(s) dropped\n", seq - last);
+			if (disconnected == 1) {
+				tm = localtime((time_t *)&now.tv_sec);
 				strftime(buf, sizeof(buf), "%F %T", tm);
 				printf("%s.%06ld: lost connection\n",
-				    buf, tv.tv_usec);
+				    buf, now.tv_nsec  * 1000);
 			}
 			continue;
 		}
-
+		if (ioctl(sock, FIONREAD, &received) == -1)
+			warn("ioctl FIONREAD");
+		if (verbose > 1)
+			printf("received %d bytes ", received);
+		addrlen = sizeof(client);
 		if ((received = recvfrom(sock, &buffer, sizeof(buffer),
 			    MSG_DONTWAIT,
 			    (struct sockaddr *) &client,
@@ -138,20 +232,20 @@ main(int argc, char *argv[])
 				    name);
 			}
 		}
-		gettimeofday(&tv, NULL);
+		if (disconnected >= THRESHOLD) {
-		if (dropped >= THRESHOLD) {
+			tm = localtime((time_t *)&now.tv_sec);
-			tm = localtime((time_t *)&tv.tv_sec);
 			strftime(buf, sizeof(buf), "%F %T", tm);
 			printf("%s.%06ld: connection is back\n",
-			    buf, tv.tv_usec);
+			    buf, now.tv_nsec/1000);
 			if (verbose)
-				printf("dropped %d paquets\n", dropped);
+				printf("dropped %d paquets\n", seq - last);
-			dropped = 0;
+			exit(3);
 		}
+		disconnected = 0;
 		last = buffer;
-		if (verbose)
+		if (verbose > 1)
-			printf("%d %ld.%06ld\n", buffer, tv.tv_sec, tv.tv_usec);
+			printf("%d %ld.%06ld\n", buffer, (long)diff.tv_sec, 
-		usleep(100000);
+			    diff.tv_nsec/1000);
 	}
 	close(sock);
 	exit(0);