Protect sequence number lookups and updates.

* src/ping903.h (host_stat): New member: "dup_count".
* src/pinger.c (hostping_extract_stat): Extract dup_count.
(hostping_reset): Initialize dup_count.
(get_hostping_stat): Store dup_count as "dup".
(seqno_mutex): New variable.
(hostping_from_seqno): Fix eventual null pointer dereference.
Return NULL on duplicate reply. Lock seqidx while updating it.
(send_echo): Reorganize.  Lock seqidx during updates.

2 files changed, 58 insertions, 40 deletions

diff --git a/src/ping903.h b/src/ping903.h
index 1390152..ccf62b7 100644
--- a/src/ping903.h
+++ b/src/ping903.h
@@ -108,6 +108,7 @@ struct host_stat {
 	struct timeval stop_tv;
 	unsigned long xmit_count;
 	unsigned long recv_count;
+	unsigned long dup_count;
 	double tmin;             /* minimum round trip time */
 	double tmax;             /* maximum round trip time */
 	double avg;
@@ -131,6 +132,7 @@ typedef struct hostping {
 	struct timeval recv_tv;
 	unsigned long xmit_count;
 	unsigned long recv_count;
+	unsigned long dup_count;
 	double tmin;             /* minimum round trip time */
 	double tmax;             /* maximum round trip time */
 	double tsum;             /* sum of all times, for doing average */
diff --git a/src/pinger.c b/src/pinger.c
index 4ab54f3..2291a48 100644
--- a/src/pinger.c
+++ b/src/pinger.c
@@ -270,6 +270,7 @@ hostping_extract_stat(HOSTPING *host, struct host_stat *st)
 	       sizeof(host->stat_last.stop_tv));
 	st->xmit_count = host->xmit_count;
 	st->recv_count = host->recv_count;
+	st->dup_count  = host->dup_count;
 	st->tmin       = host->tmin;            
 	st->tmax       = host->tmax;
 	if (host->recv_count > 0) {
@@ -300,6 +301,7 @@ hostping_reset(HOSTPING *host)
 		hostping_commit(host);
 	host->xmit_count = 0;
 	host->recv_count = 0;
+	host->dup_count = 0;
 	host->tmin = HOSTPING_TMIN_INIT;
 	host->tmax = 0;
 	host->tsum = 0;
@@ -393,6 +395,9 @@ get_hostping_stat(HOSTPING *host, struct json_value **retval)
 		if (!(v = json_new_number(st->recv_count))
 		    || json_object_set(obj, "recv", v))
 			goto err;
+		if (!(v = json_new_number(st->dup_count))
+		    || json_object_set(obj, "dup", v))
+			goto err;
 		if (!(v = json_new_number((double) 100
 					  * (st->xmit_count - st->recv_count)
 					  / st->xmit_count))
@@ -943,14 +948,16 @@ struct seqidx {
 static struct seqidx *seqidx;
 static unsigned short next_seqno;
 
+static pthread_mutex_t seqno_mutex = PTHREAD_MUTEX_INITIALIZER;
+
 static int
-seqno_alloc(HOSTPING *addr, struct timeval *tv)
+seqno_alloc(HOSTPING *host, struct timeval *tv)
 {
 	int n = next_seqno;
 	do {
 		if (tv->tv_sec - seqidx[n].tv.tv_sec > MAX_PING_TIMEOUT) {
 			memcpy(&seqidx[n].tv, tv, sizeof(*tv));
-			seqidx[n].host = addr;
+			seqidx[n].host = host;
 			seqidx[n].replied = 0;
 			next_seqno = (n + 1) % MOD_SEQNO;
 			return n;
@@ -964,11 +971,21 @@ seqno_alloc(HOSTPING *addr, struct timeval *tv)
 static HOSTPING *
 hostping_from_seqno(int seq)
 {
-	HOSTPING *host = seqidx[seq].host;
-	if (seqidx[seq].replied)
-		info("%s:%d: DUP!", host->name, seq);
-	seqidx[seq].replied++;
-	hostping_lock(host);
+	HOSTPING *host;
+
+	pthread_mutex_lock(&seqno_mutex);
+	host = seqidx[seq].host;
+	if (host) {
+		hostping_lock(host);
+		if (seqidx[seq].replied) {
+			host->dup_count++;
+			info("%s:%d: DUP!", host->name, seq);
+			host = NULL;
+		}
+		seqidx[seq].replied++;
+	} else
+		fatal("no host found for sequence number %d", seq);
+	pthread_mutex_unlock(&seqno_mutex);
 	return host;
 }
 
@@ -1102,41 +1119,42 @@ send_echo(HOSTPING *host, unsigned char *ping_buffer)
 	ssize_t n;
 	int seqno;
 
+	pthread_mutex_lock(&seqno_mutex);
 	hostping_lock(host);
 	gettimeofday(&host->xmit_tv, NULL);
-	hostping_unlock(host);
-	
-	memcpy(icmp->icmp_data, &host->xmit_tv, sizeof(host->xmit_tv));
-	if (data_buffer)
-		memcpy(icmp->icmp_data + sizeof(host->xmit_tv), data_buffer,
-		       data_length - sizeof(host->xmit_tv));
-
-	buflen = ICMP_HEADER_LEN + data_length;
-
 	seqno = seqno_alloc(host, &host->xmit_tv);
-	if (seqno == -1) {
-		//FIXME
-		return;
-	}
+	pthread_mutex_unlock(&seqno_mutex);
 	
-	if (verbose > 2)
-		info("sending %zu bytes to %s, icmp_seq=%d", buflen, host->name,
-		     seqno);
-	icmp_generic_encode(ping_buffer, buflen, ICMP_ECHO, ping_ident, seqno);
-
-	hostping_lock(host);
-	n = sendto(ping_fd, (char *) ping_buffer, buflen, 0,
-		   host->addr, host->addrlen);
-	if (n < 0) {
-		error("%s: sendto: %s", host->name, strerror(errno));
+	if (seqno >= 0) {
+		memcpy(icmp->icmp_data, &host->xmit_tv, sizeof(host->xmit_tv));
+		if (data_buffer)
+			memcpy(icmp->icmp_data + sizeof(host->xmit_tv),
+			       data_buffer,
+			       data_length - sizeof(host->xmit_tv));
+		buflen = ICMP_HEADER_LEN + data_length;
+
+		if (verbose > 2)
+			info("sending %zu bytes to %s, icmp_seq=%d",
+			     buflen, host->name,
+			     seqno);
+		icmp_generic_encode(ping_buffer, buflen,
+				    ICMP_ECHO, ping_ident, seqno);
+
+		n = sendto(ping_fd, (char *) ping_buffer, buflen, 0,
+			   host->addr, host->addrlen);
+		if (n < 0) {
+			error("%s: sendto: %s", host->name, strerror(errno));
+		} else {
+			if (host->xmit_count == 0)
+				host->start_tv = host->xmit_tv;
+			host->xmit_count++;
+			xmit_total++;
+			if (n != buflen)
+				error("ping: wrote %s %zu chars, ret=%ld\n",
+				      host->name, buflen, n);
+		}
 	} else {
-		if (host->xmit_count == 0)
-			host->start_tv = host->xmit_tv;
-		host->xmit_count++;
-		xmit_total++;
-		if (n != buflen)
-			error("ping: wrote %s %zu chars, ret=%ld\n",
-			      host->name, buflen, n);
+		error("can't allocate sequence number for %s", host->name);
 	}
 	hostping_unlock(host);		
 }
@@ -1307,9 +1325,7 @@ p903_receiver(void *p)
 			if (host->recv_count == ping_count)
 				hostping_commit(host);
 			hostping_unlock(host);
-		} else
-			fatal("no host found for sequence number %d",
-			      icmp->icmp_seq);
+		}
 	}
 }