networking/interface.c: huke remaining big statics; use malloc for INET[6]_rresolve
return value. Went thru callers and adjusted them - code got smaller too.

function                                             old     new   delta
ip_port_str                                            -     126    +126
INET6_rresolve                                       165     182     +17
static.cache                                          20      24      +4
route_main                                          2092    2091      -1
INET_sprint                                           61      59      -2
INET_nn                                                4       -      -4
INET6_sprint                                          59      53      -6
udp_do_one                                           518     508     -10
tcp_do_one                                           433     423     -10
raw_do_one                                           494     484     -10
traceroute_main                                     4117    4105     -12
INET_rresolve                                        334     321     -13
bb_displayroutes                                     494     456     -38
snprint_ip_port                                      244       -    -244
static.buff                                          264      16    -248
------------------------------------------------------------------------------
(add/remove: 1/2 grow/shrink: 2/10 up/down: 147/-598)        Total: -451 bytes

size busybox_old busybox_unstripped
   text    data     bss     dec     hex filename
 751073    3048   14688  768809   bbb29 busybox_old
 750873    3048   14440  768361   bb969 busybox_unstripped

diff --git a/libbb/inet_common.c b/libbb/inet_common.c
index 44b44a4..8449201 100644
--- a/libbb/inet_common.c
+++ b/libbb/inet_common.c
@@ -72,26 +72,24 @@
 	return 0;
 }
 
-/* cache */
-struct addr {
-	struct sockaddr_in addr;
-	char *name;
-	int host;
-	struct addr *next;
-};
-
-static struct addr *INET_nn = NULL;	/* addr-to-name cache */
 
 /* numeric: & 0x8000: default instead of *,
  *          & 0x4000: host instead of net,
  *          & 0x0fff: don't resolve
  */
-int INET_rresolve(char *name, size_t len, struct sockaddr_in *s_in,
-				  int numeric, unsigned int netmask)
+char *INET_rresolve(struct sockaddr_in *s_in, int numeric, uint32_t netmask)
 {
-	struct hostent *ent;
-	struct netent *np;
+	/* addr-to-name cache */
+	struct addr {
+		struct addr *next;
+		struct sockaddr_in addr;
+		int host;
+		char name[1];
+	};
+	static struct addr *cache = NULL;
+
 	struct addr *pn;
+	char *name;
 	uint32_t ad, host_ad;
 	int host = 0;
 
@@ -102,7 +100,7 @@
 				  s_in->sin_family);
 #endif
 		errno = EAFNOSUPPORT;
-		return -1;
+		return NULL;
 	}
 	ad = s_in->sin_addr.s_addr;
 #ifdef DEBUG
@@ -111,62 +109,58 @@
 	if (ad == INADDR_ANY) {
 		if ((numeric & 0x0FFF) == 0) {
 			if (numeric & 0x8000)
-				safe_strncpy(name, bb_str_default, len);
-			else
-				safe_strncpy(name, "*", len);
-			return 0;
+				return xstrdup(bb_str_default);
+			return xstrdup("*");
 		}
 	}
-	if (numeric & 0x0FFF) {
-		safe_strncpy(name, inet_ntoa(s_in->sin_addr), len);
-		return 0;
-	}
+	if (numeric & 0x0FFF)
+		return xstrdup(inet_ntoa(s_in->sin_addr));
 
 	if ((ad & (~netmask)) != 0 || (numeric & 0x4000))
 		host = 1;
-	pn = INET_nn;
-	while (pn != NULL) {
+	pn = cache;
+	while (pn) {
 		if (pn->addr.sin_addr.s_addr == ad && pn->host == host) {
-			safe_strncpy(name, pn->name, len);
 #ifdef DEBUG
 			bb_error_msg("rresolve: found %s %08x in cache",
 					  (host ? "host" : "net"), (unsigned)ad);
 #endif
-			return 0;
+			return xstrdup(pn->name);
 		}
 		pn = pn->next;
 	}
 
 	host_ad = ntohl(ad);
-	np = NULL;
-	ent = NULL;
+	name = NULL;
 	if (host) {
+		struct hostent *ent;
 #ifdef DEBUG
 		bb_error_msg("gethostbyaddr (%08x)", (unsigned)ad);
 #endif
 		ent = gethostbyaddr((char *) &ad, 4, AF_INET);
-		if (ent != NULL) {
-			safe_strncpy(name, ent->h_name, len);
-		}
+		if (ent)
+			name = xstrdup(ent->h_name);
 	} else {
+		/* Hmmm... this is very rare to have named nets,
+		 * and this getnetbyaddr() call is the only one in bbox.
+		 * Maybe get rid of or make configurable? */
+		struct netent *np;
 #ifdef DEBUG
 		bb_error_msg("getnetbyaddr (%08x)", (unsigned)host_ad);
 #endif
 		np = getnetbyaddr(host_ad, AF_INET);
-		if (np != NULL) {
-			safe_strncpy(name, np->n_name, len);
-		}
+		if (np)
+			name = xstrdup(np->n_name);
 	}
-	if (!ent && !np) {
-		safe_strncpy(name, inet_ntoa(s_in->sin_addr), len);
-	}
-	pn = xmalloc(sizeof(struct addr));
+	if (!name)
+		name = xstrdup(inet_ntoa(s_in->sin_addr));
+	pn = xmalloc(sizeof(*pn) + strlen(name)); /* no '+ 1', it's already accounted for */
+	pn->next = cache;
 	pn->addr = *s_in;
-	pn->next = INET_nn;
 	pn->host = host;
-	pn->name = xstrdup(name);
-	INET_nn = pn;
-	return 0;
+	strcpy(pn->name, name);
+	cache = pn;
+	return name;
 }
 
 #ifdef CONFIG_FEATURE_IPV6
@@ -195,9 +189,9 @@
 #endif
 
 
-int INET6_rresolve(char *name, size_t len, struct sockaddr_in6 *sin6,
-				   int numeric)
+char *INET6_rresolve(struct sockaddr_in6 *sin6, int numeric)
 {
+	char name[128];
 	int s;
 
 	/* Grmpf. -FvK */
@@ -207,29 +201,25 @@
 				  sin6->sin6_family);
 #endif
 		errno = EAFNOSUPPORT;
-		return -1;
+		return NULL;
 	}
 	if (numeric & 0x7FFF) {
-		inet_ntop(AF_INET6, &sin6->sin6_addr, name, len);
-		return 0;
+		inet_ntop(AF_INET6, &sin6->sin6_addr, name, sizeof(name));
+		return xstrdup(name);
 	}
 	if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) {
-		if (numeric & 0x8000) {
-			strcpy(name, bb_str_default);
-		} else {
-			name[0] = '*';
-			name[1] = '\0';
-		}
-		return 0;
+		if (numeric & 0x8000)
+			return xstrdup(bb_str_default);
+		return xstrdup("*");
 	}
 
 	s = getnameinfo((struct sockaddr *) sin6, sizeof(struct sockaddr_in6),
-				name, len, NULL, 0, 0);
+				name, sizeof(name), NULL, 0, 0);
 	if (s) {
 		bb_error_msg("getnameinfo failed");
-		return -1;
+		return NULL;
 	}
-	return 0;
+	return xstrdup(name);
 }
 
 #endif							/* CONFIG_FEATURE_IPV6 */