In preparation for merging of ping(8) and ping6(8) the -n flag needs to

become the default. That means no DNS reverse look ups per default.
In practice this doesn't change anything since ping(8) only did
reverse DNS look ups per for weird corner cases:
1) Something that's not an echo reply and -v was specified
2) LSRR or RR IP options

With this pr_addr() can become the default address printing mechanism
and can be made AF independent. With that we get ping(8)'s -H option
for free.

OK sthen@, benno@
OK deraadt@ for the -H a long time ago when this were two diffs.
man page tweak jmc@ a long time ago
deraadt@ softened up and has no objections to -n per default
beck@ is in favor of no look ups per default.

2 files changed, 48 insertions, 36 deletions

diff --git a/sbin/ping/ping.8 b/sbin/ping/ping.8
index dd39e6699e5..0f830cf9cf8 100644
--- a/sbin/ping/ping.8
+++ b/sbin/ping/ping.8
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ping.8,v 1.52 2014/03/24 11:11:49 mpi Exp $
+.\"	$OpenBSD: ping.8,v 1.53 2016/09/02 21:46:18 florian Exp $
 .\"	$NetBSD: ping.8,v 1.10 1995/12/31 04:55:35 ghudson Exp $
 .\"
 .\" Copyright (c) 1985, 1991, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"     @(#)ping.8	8.2 (Berkeley) 12/11/93
 .\"
-.Dd $Mdocdate: March 24 2014 $
+.Dd $Mdocdate: September 2 2016 $
 .Dt PING 8
 .Os
 .Sh NAME
@@ -39,7 +39,7 @@
 .Sh SYNOPSIS
 .Nm ping
 .Bk -words
-.Op Fl DdEefLnqRv
+.Op Fl DdEefHLnqRv
 .Op Fl c Ar count
 .Op Fl I Ar ifaddr
 .Op Fl i Ar wait
@@ -116,6 +116,8 @@ Only the superuser may use this option.
 .Bf -emphasis
 This can be very hard on a network and should be used with caution.
 .Ef
+.It Fl H
+Try reverse lookups for addresses.
 .It Fl I Ar ifaddr
 Specify the interface address to transmit from
 on machines with multiple interfaces.
@@ -144,7 +146,7 @@ mode of behavior.
 Only root may set a preload value.
 .It Fl n
 Numeric output only.
-No attempt will be made to look up symbolic names for host addresses.
+No attempt will be made to look up symbolic names from addresses in the reply.
 .It Fl p Ar pattern
 You may specify up to 16
 .Dq pad
diff --git a/sbin/ping/ping.c b/sbin/ping/ping.c
index b468b088de2..db7d64bef15 100644
--- a/sbin/ping/ping.c
+++ b/sbin/ping/ping.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ping.c,v 1.143 2016/09/02 14:15:58 florian Exp $	*/
+/*	$OpenBSD: ping.c,v 1.144 2016/09/02 21:46:18 florian Exp $	*/
 /*	$NetBSD: ping.c,v 1.20 1995/08/11 22:37:58 cgd Exp $	*/
 
 /*
@@ -104,7 +104,7 @@ struct payload {
 int options;
 #define	F_FLOOD		0x0001
 #define	F_INTERVAL	0x0002
-#define	F_NUMERIC	0x0004
+#define	F_HOSTNAME	0x0004
 #define	F_PINGFILLED	0x0008
 #define	F_QUIET		0x0010
 #define	F_RROUTE	0x0020
@@ -173,7 +173,7 @@ int in_cksum(u_short *, int);
 void onsignal(int);
 void retransmit(void);
 int pinger(void);
-char *pr_addr(in_addr_t);
+const char *pr_addr(struct sockaddr *, socklen_t);
 int check_icmph(struct ip *);
 void pr_icmph(struct icmp *);
 void pr_pack(char *, int, struct msghdr *);
@@ -215,7 +215,7 @@ main(int argc, char *argv[])
 	preload = 0;
 	datap = &outpack[8 + sizeof(struct payload)];
 	while ((ch = getopt(argc, argv,
-	    "DEI:LRS:c:defi:l:np:qs:T:t:V:vw:")) != -1)
+	    "DEI:LRS:c:defHi:l:np:qs:T:t:V:vw:")) != -1)
 		switch(ch) {
 		case 'c':
 			npackets = strtonum(optarg, 0, INT64_MAX, &errstr);
@@ -243,6 +243,9 @@ main(int argc, char *argv[])
 			options |= F_FLOOD;
 			setvbuf(stdout, NULL, _IONBF, 0);
 			break;
+		case 'H':
+			options |= F_HOSTNAME;
+			break;
 		case 'I':
 		case 'S':	/* deprecated */
 			source = optarg;
@@ -280,7 +283,7 @@ main(int argc, char *argv[])
 				    optarg);
 			break;
 		case 'n':
-			options |= F_NUMERIC;
+			options &= ~F_HOSTNAME;
 			break;
 		case 'p':		/* fill buffer with user pattern */
 			options |= F_PINGFILLED;
@@ -499,16 +502,16 @@ main(int argc, char *argv[])
 
 	if (to->sin_family == AF_INET)
 		(void)printf("PING %s (%s): %d data bytes\n", hostname,
-		    inet_ntoa(*(struct in_addr *)&to->sin_addr.s_addr),
+		    pr_addr((struct sockaddr *)to, sizeof(*to)),
 		    datalen);
 	else
 		(void)printf("PING %s: %d data bytes\n", hostname, datalen);
 
-	if (options & F_NUMERIC) {
-		if (pledge("stdio inet", NULL) == -1)
+	if (options & F_HOSTNAME) {
+		if (pledge("stdio inet dns", NULL) == -1)
 			err(1, "pledge");
 	} else {
-		if (pledge("stdio inet dns", NULL) == -1)
+		if (pledge("stdio inet", NULL) == -1)
 			err(1, "pledge");
 	}
 
@@ -746,7 +749,7 @@ pinger(void)
 void
 pr_pack(char *buf, int cc, struct msghdr *mhdr)
 {
-	struct sockaddr_in *from;
+	struct sockaddr_in *from, s_in;
 	socklen_t fromlen;
 	struct icmp *icp;
 	in_addr_t l;
@@ -761,6 +764,9 @@ pr_pack(char *buf, int cc, struct msghdr *mhdr)
 	int hlen, hlen2, dupflag;
 	struct payload payload;
 
+	s_in.sin_len = sizeof(s_in);
+	s_in.sin_family = AF_INET;
+
 	if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
 		err(1, "clock_gettime(CLOCK_MONOTONIC)");
 
@@ -780,7 +786,7 @@ pr_pack(char *buf, int cc, struct msghdr *mhdr)
 	if (cc < hlen + ICMP_MINLEN) {
 		if (options & F_VERBOSE)
 			warnx("packet too short (%d bytes) from %s", cc,
-			    inet_ntoa(*(struct in_addr *)&from->sin_addr.s_addr));
+			    pr_addr((struct sockaddr*)from, fromlen));
 		return;
 	}
 
@@ -847,7 +853,7 @@ pr_pack(char *buf, int cc, struct msghdr *mhdr)
 			(void)write(STDOUT_FILENO, &BSPACE, 1);
 		else {
 			(void)printf("%d bytes from %s: icmp_seq=%u", cc,
-			    inet_ntoa(*(struct in_addr *)&from->sin_addr.s_addr),
+			    pr_addr((struct sockaddr*)from, fromlen),
 			    ntohs(icp->icmp_seq));
 			(void)printf(" ttl=%d", ip->ip_ttl);
 			if (cc >= 8 + sizeof(struct payload))
@@ -886,7 +892,7 @@ pr_pack(char *buf, int cc, struct msghdr *mhdr)
 		if (cc >= hlen2 + 8 && check_icmph(ip2) != 1)
 			return;
 		(void)printf("%d bytes from %s: ", cc,
-		    pr_addr(from->sin_addr.s_addr));
+		    pr_addr((struct sockaddr*)from, fromlen));
 		pr_icmph(icp);
 	}
 
@@ -912,9 +918,12 @@ pr_pack(char *buf, int cc, struct msghdr *mhdr)
 					l = (l<<8) + *++cp;
 					if (l == 0)
 						(void)printf("\t0.0.0.0");
-					else
+					else {
+						s_in.sin_addr.s_addr = ntohl(l);
 						(void)printf("\t%s",
-						    pr_addr(ntohl(l)));
+						    pr_addr((struct sockaddr*)
+						    &s_in, sizeof(s_in)));
+					}
 					hlen -= 4;
 					j -= 4;
 					i += 4;
@@ -962,8 +971,12 @@ pr_pack(char *buf, int cc, struct msghdr *mhdr)
 				l = (l<<8) + *++cp;
 				if (l == 0)
 					(void)printf("\t0.0.0.0");
-				else
-					(void)printf("\t%s", pr_addr(ntohl(l)));
+				else {
+					s_in.sin_addr.s_addr = ntohl(l);
+					(void)printf("\t%s",
+					    pr_addr((struct sockaddr*)&s_in,
+					    sizeof(s_in)));
+				}
 				hlen -= 4;
 				i -= 4;
 				j += 4;
@@ -1257,24 +1270,21 @@ pr_iph(struct ip *ip)
 
 /*
  * pr_addr --
- *	Return an ascii host address as a dotted quad and optionally with
- * a hostname.
+ *	Return address in numeric form or a host name
  */
-char *
-pr_addr(in_addr_t a)
+const char *
+pr_addr(struct sockaddr *addr, socklen_t addrlen)
 {
-	struct hostent *hp;
-	struct in_addr in;
-	static char buf[16+3+HOST_NAME_MAX+1];
+	static char buf[NI_MAXHOST];
+	int flag = 0;
+
+	if ((options & F_HOSTNAME) == 0)
+		flag |= NI_NUMERICHOST;
 
-	in.s_addr = a;
-	if ((options & F_NUMERIC) ||
-	    !(hp = gethostbyaddr((char *)&in.s_addr, sizeof(in.s_addr), AF_INET)))
-		(void)snprintf(buf, sizeof buf, "%s", inet_ntoa(in));
+	if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0, flag) == 0)
+		return (buf);
 	else
-		(void)snprintf(buf, sizeof buf, "%s (%s)", hp->h_name,
-		    inet_ntoa(in));
-	return(buf);
+		return "?";
 }
 
 /*
@@ -1414,7 +1424,7 @@ __dead void
 usage(void)
 {
 	(void)fprintf(stderr,
-	    "usage: ping [-DdEefLnqRv] [-c count] [-I ifaddr] [-i wait]\n"
+	    "usage: ping [-DdEefHLnqRv] [-c count] [-I ifaddr] [-i wait]\n"
 	    "\t[-l preload] [-p pattern] [-s packetsize]"
 #ifndef	SMALL
 	    " [-T toskeyword]"