When building dynamic hostent and netent, allocate a single linear buffer to

hold both the structure and the data. The freehostent() and freenetent() API
functions are not needed anymore.  While there, ensure that the constructed
addr and alias lists are really NULL terminated.

1 files changed, 42 insertions, 47 deletions

diff --git a/lib/libc/asr/gethostnamadr_async.c b/lib/libc/asr/gethostnamadr_async.c
index 47fecca10da..bc338d71776 100644
--- a/lib/libc/asr/gethostnamadr_async.c
+++ b/lib/libc/asr/gethostnamadr_async.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gethostnamadr_async.c,v 1.5 2012/07/12 13:03:34 eric Exp $	*/
+/*	$OpenBSD: gethostnamadr_async.c,v 1.6 2012/08/19 16:17:40 eric Exp $	*/
 /*
  * Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
  *
@@ -34,6 +34,11 @@
 #define MAXALIASES	16
 #define MAXADDRS	16
 
+#define HOSTENT_PTR(h) ((char**)(((char*)h) + sizeof (*h)))
+#define HOSTENT_POS(h)  HOSTENT_PTR(h)[0]
+#define HOSTENT_STOP(h)	HOSTENT_PTR(h)[1]
+#define HOSTENT_LEFT(h) (HOSTENT_STOP(h) - HOSTENT_POS(h))
+
 ssize_t addr_as_fqdn(const char *, int, char *, size_t);
 
 static int gethostnamadr_async_run(struct async *, struct async_res *);
@@ -291,7 +296,7 @@ gethostnamadr_async_run(struct async *as, struct async_res *ar)
 			if (hostent_add_addr(ar->ar_hostent,
 			    as->as.hostnamadr.addr,
 			    as->as.hostnamadr.addrlen) == -1) {
-				freehostent(ar->ar_hostent);
+				free(ar->ar_hostent);
 				ar->ar_errno = errno;
 				ar->ar_h_errno = NETDB_INTERNAL;
 				async_set_state(as, ASR_STATE_HALT);
@@ -305,7 +310,7 @@ gethostnamadr_async_run(struct async *as, struct async_res *ar)
 		 */
 		if (as->as_type == ASR_GETHOSTBYNAME &&
 		    ar->ar_hostent->h_addr_list[0] == NULL) {
-			freehostent(ar->ar_hostent);
+			free(ar->ar_hostent);
 			async_set_state(as, ASR_STATE_NEXT_DB);
 			break;
 		}
@@ -381,7 +386,7 @@ found:
 		goto fail;
 	return (h);
 fail:
-	freehostent(h);
+	free(h);
 	return (NULL);
 }
 
@@ -454,7 +459,7 @@ hostent_from_packet(int reqtype, int family, char *pkt, size_t pktlen)
 
 	return (h);
 fail:
-	freehostent(h);
+	free(h);
 	return (NULL);
 }
 
@@ -462,19 +467,19 @@ static struct hostent *
 hostent_alloc(int family)
 {
 	struct hostent	*h;
+	size_t		 alloc;
 
-	h = calloc(1, sizeof *h);
-	if (h == NULL)
+	alloc = sizeof(*h) + (2 + MAXALIASES + MAXADDRS) * sizeof(char*) + 1024;
+	if ((h = calloc(1, alloc)) == NULL)
 		return (NULL);
 
-	h->h_aliases = calloc(MAXALIASES, sizeof *h->h_aliases);
-	h->h_addr_list = calloc(MAXADDRS, sizeof *h->h_addr_list);
-	if (h->h_aliases == NULL || h->h_addr_list == NULL) {
-		freehostent(h);
-		return (NULL);
-	}
 	h->h_addrtype = family;
 	h->h_length = (family == AF_INET) ? 4 : 16;
+	h->h_aliases = HOSTENT_PTR(h) + 2;
+	h->h_addr_list = h->h_aliases + MAXALIASES;
+
+	HOSTENT_STOP(h) = (char*)(h) + alloc;
+	HOSTENT_POS(h) = (char*)(h->h_addr_list + MAXADDRS);
 
 	return (h);
 }
@@ -490,12 +495,14 @@ hostent_set_cname(struct hostent *h, const char *name, int isdname)
 	if (isdname) {
 		asr_strdname(name, buf, sizeof buf);
 		buf[strlen(buf) - 1] = '\0';
-		h->h_name = strdup(buf);
-	} else {
-		h->h_name = strdup(name);
+		name = buf;
 	}
-	if (h->h_name == NULL)
-		return (-1);
+	if (strlen(name) + 1 >= HOSTENT_LEFT(h))
+		return (1);
+
+	strlcpy(HOSTENT_POS(h), name, HOSTENT_LEFT(h));
+	h->h_name = HOSTENT_POS(h);
+	HOSTENT_POS(h) += strlen(name) + 1;
 
 	return (0);
 }
@@ -506,21 +513,23 @@ hostent_add_alias(struct hostent *h, const char *name, int isdname)
 	char	buf[MAXDNAME];
 	size_t	i;
 
-	for (i = 0; i < MAXALIASES; i++)
+	for (i = 0; i < MAXALIASES - 1; i++)
 		if (h->h_aliases[i] == NULL)
 			break;
-	if (i == MAXALIASES)
+	if (i == MAXALIASES - 1)
 		return (0);
 
 	if (isdname) {
 		asr_strdname(name, buf, sizeof buf);
 		buf[strlen(buf)-1] = '\0';
-		h->h_aliases[i] = strdup(buf);
-	} else {
-		h->h_aliases[i] = strdup(name);
+		name = buf;
 	}
-	if (h->h_aliases[i] == NULL)
-		return (-1);
+	if (strlen(name) + 1 >= HOSTENT_LEFT(h))
+		return (1);
+
+	strlcpy(HOSTENT_POS(h), name, HOSTENT_LEFT(h));
+	h->h_aliases[i] = HOSTENT_POS(h);
+	HOSTENT_POS(h) += strlen(name) + 1;
 
 	return (0);
 }
@@ -530,36 +539,22 @@ hostent_add_addr(struct hostent *h, const void *addr, int size)
 {
 	int	i;
 
-	for (i = 0; i < MAXADDRS; i++)
+	for (i = 0; i < MAXADDRS - 1; i++)
 		if (h->h_addr_list[i] == NULL)
 			break;
-	if (i == MAXADDRS)
+	if (i == MAXADDRS - 1)
 		return (0);
 
-	h->h_addr_list[i] = malloc(size);
-	if (h->h_addr_list[i] == NULL)
-		return (-1);
-	memmove(h->h_addr_list[i], addr, size);
+	if (size >= HOSTENT_LEFT(h))
+		return (1);
 
-	return (0);
-}
+	memmove(HOSTENT_POS(h), addr, size);
+	h->h_addr_list[i] = HOSTENT_POS(h);
+	HOSTENT_POS(h) += size;
 
-void
-freehostent(struct hostent *h)
-{
-	char **c;
-
-	free(h->h_name);
-	for (c = h->h_aliases; *c; c++)
-		free(*c);
-	free(h->h_aliases);
-	for (c = h->h_addr_list; *c; c++)
-		free(*c);
-	free(h->h_addr_list);
-	free(h);
+	return (0);
 }
 
-
 ssize_t
 addr_as_fqdn(const char *addr, int family, char *dst, size_t max)
 {