libalias: replace placeholder with static constant

The field nullAddress in struct libalias is never set and never used.
It exists as a placeholder for an unused argument only.

Reviewed by:	hselasky
Differential Revision: https://reviews.freebsd.org/D30253

(cherry picked from commit 189f8eea138a78b09c9f19114b1362b0df1cf87d)
(cherry picked from commit b03a41befeaf17ef25da96fc7bc2dc19c9a6b253)

2 files changed, 13 insertions, 12 deletions

diff --git a/sys/netinet/libalias/alias_db.c b/sys/netinet/libalias/alias_db.c
index cd29c16ac945..7a84cf310d5a 100644
--- a/sys/netinet/libalias/alias_db.c
+++ b/sys/netinet/libalias/alias_db.c
@@ -224,6 +224,9 @@ static LIST_HEAD(, libalias) instancehead = LIST_HEAD_INITIALIZER(instancehead);
 #define NO_DEST_PORT     1
 #define NO_SRC_PORT      1
 
+/* Matches any/unknown address in FindLinkIn/Out() and AddLink(). */
+static struct in_addr const ANY_ADDR = { INADDR_ANY };
+
 /* Data Structures
 
     The fundamental data structure used in this program is
@@ -1111,12 +1114,12 @@ _FindLinkOut(struct libalias *la, struct in_addr src_addr,
 			lnk = _FindLinkOut(la, src_addr, dst_addr, src_port, 0,
 			    link_type, 0);
 			if (lnk == NULL)
-				lnk = _FindLinkOut(la, src_addr, la->nullAddress, src_port,
+				lnk = _FindLinkOut(la, src_addr, ANY_ADDR, src_port,
 				    dst_port, link_type, 0);
 		}
 		if (lnk == NULL &&
 		    (dst_port != 0 || dst_addr.s_addr != INADDR_ANY)) {
-			lnk = _FindLinkOut(la, src_addr, la->nullAddress, src_port, 0,
+			lnk = _FindLinkOut(la, src_addr, ANY_ADDR, src_port, 0,
 			    link_type, 0);
 		}
 		if (lnk != NULL) {
@@ -1152,7 +1155,7 @@ FindLinkOut(struct libalias *la, struct in_addr src_addr,
 		 */
 		if (la->aliasAddress.s_addr != INADDR_ANY &&
 		    src_addr.s_addr == la->aliasAddress.s_addr) {
-			lnk = _FindLinkOut(la, la->nullAddress, dst_addr, src_port, dst_port,
+			lnk = _FindLinkOut(la, ANY_ADDR, dst_addr, src_port, dst_port,
 			    link_type, replace_partial_links);
 		}
 	}
@@ -1294,7 +1297,7 @@ FindLinkIn(struct libalias *la, struct in_addr dst_addr,
 		 */
 		if (la->aliasAddress.s_addr != INADDR_ANY &&
 		    alias_addr.s_addr == la->aliasAddress.s_addr) {
-			lnk = _FindLinkIn(la, dst_addr, la->nullAddress, dst_port, alias_port,
+			lnk = _FindLinkIn(la, dst_addr, ANY_ADDR, dst_port, alias_port,
 			    link_type, replace_partial_links);
 		}
 	}
@@ -1376,7 +1379,7 @@ FindFragmentIn1(struct libalias *la, struct in_addr dst_addr,
 	    LINK_FRAGMENT_ID, 0);
 
 	if (lnk == NULL) {
-		lnk = AddLink(la, la->nullAddress, dst_addr, alias_addr,
+		lnk = AddLink(la, ANY_ADDR, dst_addr, alias_addr,
 		    NO_SRC_PORT, NO_DEST_PORT, ip_id,
 		    LINK_FRAGMENT_ID);
 	}
@@ -1399,7 +1402,7 @@ AddFragmentPtrLink(struct libalias *la, struct in_addr dst_addr,
     u_short ip_id)
 {
 	LIBALIAS_LOCK_ASSERT(la);
-	return AddLink(la, la->nullAddress, dst_addr, la->nullAddress,
+	return AddLink(la, ANY_ADDR, dst_addr, ANY_ADDR,
 	    NO_SRC_PORT, NO_DEST_PORT, ip_id,
 	    LINK_FRAGMENT_PTR);
 }
@@ -1409,7 +1412,7 @@ FindFragmentPtr(struct libalias *la, struct in_addr dst_addr,
     u_short ip_id)
 {
 	LIBALIAS_LOCK_ASSERT(la);
-	return FindLinkIn(la, dst_addr, la->nullAddress,
+	return FindLinkIn(la, dst_addr, ANY_ADDR,
 	    NO_DEST_PORT, ip_id,
 	    LINK_FRAGMENT_PTR, 0);
 }
@@ -1669,7 +1672,7 @@ FindOriginalAddress(struct libalias *la, struct in_addr alias_addr)
 	struct alias_link *lnk;
 
 	LIBALIAS_LOCK_ASSERT(la);
-	lnk = FindLinkIn(la, la->nullAddress, alias_addr,
+	lnk = FindLinkIn(la, ANY_ADDR, alias_addr,
 	    0, 0, LINK_ADDR, 0);
 	if (lnk == NULL) {
 		la->newDefaultLink = 1;
@@ -1701,7 +1704,7 @@ FindAliasAddress(struct libalias *la, struct in_addr original_addr)
 	struct alias_link *lnk;
 
 	LIBALIAS_LOCK_ASSERT(la);
-	lnk = FindLinkOut(la, original_addr, la->nullAddress,
+	lnk = FindLinkOut(la, original_addr, ANY_ADDR,
 	    0, 0, LINK_ADDR, 0);
 	if (lnk == NULL) {
 		return (la->aliasAddress.s_addr != INADDR_ANY) ?
@@ -2317,7 +2320,7 @@ LibAliasRedirectAddr(struct libalias *la, struct in_addr src_addr,
 	struct alias_link *lnk;
 
 	LIBALIAS_LOCK(la);
-	lnk = AddLink(la, src_addr, la->nullAddress, alias_addr,
+	lnk = AddLink(la, src_addr, ANY_ADDR, alias_addr,
 	    0, 0, 0,
 	    LINK_ADDR);
 
diff --git a/sys/netinet/libalias/alias_local.h b/sys/netinet/libalias/alias_local.h
index e6374a72ef75..63bfd857f14f 100644
--- a/sys/netinet/libalias/alias_local.h
+++ b/sys/netinet/libalias/alias_local.h
@@ -89,8 +89,6 @@ struct libalias {
 	/* IP address incoming packets are sent to
 	 * if no aliasing link already exists */
 	struct in_addr	targetAddress;
-	/* Used as a dummy parameter for some function calls */
-	struct in_addr	nullAddress;
 	/* Lookup table of pointers to chains of link records.
 	 * Each link record is doubly indexed into input and
 	 * output lookup tables. */