avoid signal handler race. comment and help from deraadt.

kame/kame/ping6/ping6.c

@@ -1,4 +1,4 @@
-/*	$KAME: ping6.c,v 1.110 2001/01/05 01:23:19 jinmei Exp $	*/
+/*	$KAME: ping6.c,v 1.111 2001/01/12 19:04:03 itojun Exp $	*/
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -243,13 +243,19 @@ struct msghdr smsghdr;
 struct iovec smsgiov;
 char *scmsg = 0;
 
+volatile int signo;
+volatile int seenalrm;
+volatile int seenint;
+volatile int seeninfo;
+
 int	 main __P((int, char *[]));
 void	 fill __P((char *, char *));
 int	 get_hoplim __P((struct msghdr *));
 int	 get_pathmtu __P((struct msghdr *));
 void	 set_pathmtu __P((int));
 struct in6_pktinfo *get_rcvpktinfo __P((struct msghdr *));
-void	 onalrm __P((int));
+void	 onsignal __P((int));
+void	 retransmit __P((void));
 void	 oninfo __P((int));
 void	 onint __P((int));
 void	 pinger __P((void));
@@ -281,7 +287,7 @@ main(argc, argv)
 {
 	struct itimerval itimer;
 	struct sockaddr_in6 from;
-	struct timeval timeout;
+	struct timeval timeout, *tv;
 	struct addrinfo hints;
 	fd_set *fdmaskp;
 	int fdmasks;
@@ -297,9 +303,6 @@ main(argc, argv)
 #ifdef USE_RFC2292BIS
 	struct ip6_rthdr *rthdr = NULL;
 #endif
-#ifndef __OpenBSD__
-	struct timeval tv;
-#endif
 #ifdef IPSEC_POLICY_IPSEC
 	char *policy_in = NULL;
 	char *policy_out = NULL;
@@ -638,8 +641,8 @@ main(argc, argv)
 
 	ident = getpid() & 0xFFFF;
 #ifndef __OpenBSD__
-	gettimeofday(&tv, NULL);
-	srand((unsigned int)(tv.tv_sec ^ tv.tv_usec ^ (long)ident));
+	gettimeofday(&timeout, NULL);
+	srand((unsigned int)(timeout.tv_sec ^ timeout.tv_usec ^ (long)ident));
 	memset(nonce, 0, sizeof(nonce));
 	for (i = 0; i < sizeof(nonce); i += sizeof(int))
 		*((int *)&nonce[i]) = rand();
@@ -968,23 +971,25 @@ main(argc, argv)
 	while (preload--)		/* Fire off them quickies. */
 		pinger();
 
-	(void)signal(SIGINT, onint);
+	(void)signal(SIGINT, onsignal);
 #ifdef SIGINFO
-	(void)signal(SIGINFO, oninfo);
+	(void)signal(SIGINFO, onsignal);
 #endif
 
 	if ((options & F_FLOOD) == 0) {
-		(void)signal(SIGALRM, onalrm);
+		(void)signal(SIGALRM, onsignal);
 		itimer.it_interval = interval;
-		itimer.it_value.tv_sec = 0;
-		itimer.it_value.tv_usec = 1;
+		itimer.it_value = interval;
 		(void)setitimer(ITIMER_REAL, &itimer, NULL);
+		retransmit();
 	}
 
-	fdmasks = howmany(s+1, NFDBITS);
+	fdmasks = howmany(s + 1, NFDBITS) * sizeof(fd_mask);
 	if ((fdmaskp = malloc(fdmasks)) == NULL)
 		err(1, "malloc");
 
+	signo = seenalrm = seenint = seeninfo = 0;
+
 	for (;;) {
 		struct msghdr m;
 		struct cmsghdr *cm;
@@ -995,11 +1000,31 @@ main(argc, argv)
 			pinger();
 			timeout.tv_sec = 0;
 			timeout.tv_usec = 10000;
-			memset(fdmaskp, 0, fdmasks);
-			FD_SET(s, fdmaskp);
-			if (select(s + 1, fdmaskp, NULL, NULL, &timeout) < 1)
-				continue;
-		}
+			tv = &timeout;
+		} else
+			tv = NULL;
+		memset(fdmaskp, 0, fdmasks);
+		FD_SET(s, fdmaskp);
+		cc = select(s + 1, fdmaskp, NULL, NULL, tv);
+		if ((cc < 0 && errno == EINTR) || (options & F_FLOOD)) {
+			if (!signo)
+				break;
+			if (seenalrm) {
+				retransmit();
+				seenalrm = 0;
+			}
+			if (seenint) {
+				onint(SIGINT);
+				seenint = 0;
+			}
+			if (seeninfo) {
+				oninfo(SIGINFO);
+				seeninfo = 0;
+			}
+			continue;
+		} else if (cc == 0)
+			continue;
+
 		fromlen = sizeof(from);
 
 		m.msg_name = (caddr_t)&from;
@@ -1013,13 +1038,28 @@ main(argc, argv)
 		m.msg_control = (caddr_t)buf;
 		m.msg_controllen = sizeof(buf);
 
-		if ((cc = recvmsg(s, &m, 0)) < 0) {
-			if (errno == EINTR)
+		cc = recvmsg(s, &m, 0);
+		if (cc < 0) {
+			if (errno != EINTR) {
+				warn("recvmsg");
+				continue;
+			}
+			if (!signo)
 				continue;
-			warn("recvmsg");
+			if (seenalrm) {
+				retransmit();
+				seenalrm = 0;
+			}
+			if (seenint) {
+				onint(SIGINT);
+				seenint = 0;
+			}
+			if (seeninfo) {
+				oninfo(SIGINFO);
+				seeninfo = 0;
+			}
 			continue;
-		}
-		else if (cc == 0) {
+		} else if (cc == 0) {
 			int mtu;
 
 			/*
@@ -1035,8 +1075,7 @@ main(argc, argv)
 				set_pathmtu(mtu);
 			}
 			continue;
-		}
-		else {
+		} else {
 			/*
 			 * an ICMPv6 message (probably an echoreply) arrived.
 			 */
@@ -1049,14 +1088,30 @@ main(argc, argv)
 	exit(nreceived == 0);
 }
 
+void
+onsignal(sig)
+	int sig;
+{
+	signo = sig;
+	switch (sig) {
+	case SIGALRM:
+		seenalrm++;
+		break;
+	case SIGINT:
+		seenint++;
+		break;
+	case SIGINFO:
+		seeninfo++;
+		break;
+	}
+}
+
 /*
- * onalrm --
+ * retransmit --
  *	This routine transmits another ping6.
  */
-/* ARGSUSED */
 void
-onalrm(signo)
-	int signo;
+retransmit()
 {
 	struct itimerval itimer;
 
@@ -2044,10 +2099,8 @@ void
 oninfo(notused)
 	int notused;
 {
-	int save_errno = errno;
 
 	summary();
-	errno = save_errno;
 }
 
 /*