tcpdump/backport-0002-Use-getnameinfo-instead-of-gethostbyaddr.patch

diff --git a/addrtoname.c b/addrtoname.c
index 33b9378..426839c 100644
--- a/addrtoname.c
+++ b/addrtoname.c
@@ -277,7 +277,6 @@ extern cap_channel_t *capdns;
 const char *
 ipaddr_string(netdissect_options *ndo, const u_char *ap)
 {
-	struct hostent *hp;
 	uint32_t addr;
 	struct hnamemem *p;
 
@@ -299,13 +298,29 @@ ipaddr_string(netdissect_options *ndo, const u_char *ap)
 	 */
 	if (!ndo->ndo_nflag &&
 	    (addr & f_netmask) == f_localnet) {
-#ifdef HAVE_CASPER
-		if (capdns != NULL) {
-			hp = cap_gethostbyaddr(capdns, (char *)&addr, 4,
-			    AF_INET);
-		} else
-#endif
-			hp = gethostbyaddr((char *)&addr, 4, AF_INET);
+#ifdef HAVE_GETNAMEINFO
+		struct sockaddr_in sa;
+		char hbuf[NI_MAXHOST];
+
+		memset(&sa, 0, sizeof (sa));
+		sa.sin_family = AF_INET;
+		sa.sin_addr.s_addr = addr;
+		if (!getnameinfo((struct sockaddr *)&sa, sizeof (sa),
+					hbuf, sizeof (hbuf), NULL, 0, 0)) {
+			if (ndo->ndo_Nflag) {
+				char *dotp;
+
+				/* Remove domain qualifications */
+				dotp = strchr(hbuf, '.');
+				if (dotp)
+					*dotp = '\0';
+			}
+			p->name = strdup(hbuf);
+			return p->name;
+		}
+#else
+		struct hostent *hp;
+		hp = gethostbyaddr((char *)&addr, 4, AF_INET);
 		if (hp) {
 			char *dotp;
 
@@ -321,6 +336,7 @@ ipaddr_string(netdissect_options *ndo, const u_char *ap)
 			}
 			return (p->name);
 		}
+#endif
 	}
 	p->name = strdup(intoa(addr));
 	if (p->name == NULL)
@@ -336,7 +352,6 @@ ipaddr_string(netdissect_options *ndo, const u_char *ap)
 const char *
 ip6addr_string(netdissect_options *ndo, const u_char *ap)
 {
-	struct hostent *hp;
 	union {
 		nd_ipv6 addr;
 		struct for_hash_addr {
@@ -361,13 +376,29 @@ ip6addr_string(netdissect_options *ndo, const u_char *ap)
 	 * Do not print names if -n was given.
 	 */
 	if (!ndo->ndo_nflag) {
-#ifdef HAVE_CASPER
-		if (capdns != NULL) {
-			hp = cap_gethostbyaddr(capdns, (char *)&addr,
-			    sizeof(addr), AF_INET6);
-		} else
-#endif
-			hp = gethostbyaddr((char *)&addr, sizeof(addr),
+#ifdef HAVE_GETNAMEINFO
+		struct sockaddr_in6 sa;
+		char hbuf[NI_MAXHOST];
+
+		memset(&sa, 0, sizeof (sa));
+		sa.sin6_family = AF_INET6;
+		sa.sin6_addr = addr.addr;
+		if (!getnameinfo((struct sockaddr *)&sa, sizeof (sa),
+					hbuf, sizeof (hbuf), NULL, 0, 0)) {
+			if (ndo->ndo_Nflag) {
+				char *dotp;
+
+				/* Remove domain qualifications */
+				dotp = strchr(hbuf, '.');
+				if (dotp)
+					*dotp = '\0';
+			}
+			p->name = strdup(hbuf);
+			return p->name;
+		}
+#else
+		struct hostent *hp;
+		hp = gethostbyaddr((char *)&addr, sizeof(addr),
 			    AF_INET6);
 		if (hp) {
 			char *dotp;
@@ -384,6 +415,7 @@ ip6addr_string(netdissect_options *ndo, const u_char *ap)
 			}
 			return (p->name);
 		}
+#endif
 	}
 	cp = addrtostr6(ap, ntop_buf, sizeof(ntop_buf));
 	p->name = strdup(cp);