routed(8): use NULL instead of zero for pointers.

10 files changed, 230 insertions, 227 deletions

diff --git a/sbin/routed/if.c b/sbin/routed/if.c
index 9160e6f..fadb9af 100644
--- a/sbin/routed/if.c
+++ b/sbin/routed/if.c
@@ -110,14 +110,14 @@ if_link(struct interface *ifp)
 
 	hifp = AHASH(ifp->int_addr);
 	ifp->int_ahash_prev = hifp;
-	if ((ifp->int_ahash = *hifp) != 0)
+	if ((ifp->int_ahash = *hifp) != NULL)
 		(*hifp)->int_ahash_prev = &ifp->int_ahash;
 	*hifp = ifp;
 
 	if (ifp->int_if_flags & IFF_BROADCAST) {
 		hifp = BHASH(ifp->int_brdaddr);
 		ifp->int_bhash_prev = hifp;
-		if ((ifp->int_bhash = *hifp) != 0)
+		if ((ifp->int_bhash = *hifp) != NULL)
 			(*hifp)->int_bhash_prev = &ifp->int_bhash;
 		*hifp = ifp;
 	}
@@ -128,11 +128,11 @@ if_link(struct interface *ifp)
 	hifp = nhash(ifp->int_name);
 	if (ifp->int_state & IS_ALIAS) {
 		/* put aliases on the end of the hash chain */
-		while (*hifp != 0)
+		while (*hifp != NULL)
 			hifp = &(*hifp)->int_nhash;
 	}
 	ifp->int_nhash_prev = hifp;
-	if ((ifp->int_nhash = *hifp) != 0)
+	if ((ifp->int_nhash = *hifp) != NULL)
 		(*hifp)->int_nhash_prev = &ifp->int_nhash;
 	*hifp = ifp;
 }
@@ -145,7 +145,7 @@ ifwithaddr(naddr addr,
 	   int	bcast,			/* notice IFF_BROADCAST address */
 	   int	remote)			/* include IS_REMOTE interfaces */
 {
-	struct interface *ifp, *possible = 0;
+	struct interface *ifp, *possible = NULL;
 
 	remote = (remote == 0) ? IS_REMOTE : 0;
 
@@ -185,7 +185,7 @@ ifwithname(char *name,			/* "ec0" or whatever */
 	struct interface *ifp;
 
 	for (;;) {
-		for (ifp = *nhash(name); ifp != 0; ifp = ifp->int_nhash) {
+		for (ifp = *nhash(name); ifp != NULL; ifp = ifp->int_nhash) {
 			/* If the network address is not specified,
 			 * ignore any alias interfaces.  Otherwise, look
 			 * for the interface with the target name and address.
@@ -239,7 +239,7 @@ iflookup(naddr addr)
 	struct interface *ifp, *maybe;
 	int once = 0;
 
-	maybe = 0;
+	maybe = NULL;
 	for (;;) {
 		LIST_FOREACH(ifp, &ifnet, int_list) {
 			if (ifp->int_if_flags & IFF_POINTOPOINT) {
@@ -255,13 +255,13 @@ iflookup(naddr addr)
 				/* Look for the longest approximate match.
 				 */
 				if (on_net(addr, ifp->int_net, ifp->int_mask)
-				    && (maybe == 0
+				    && (maybe == NULL
 					|| ifp->int_mask > maybe->int_mask))
 					maybe = ifp;
 			}
 		}
 
-		if (maybe != 0 || once || IF_RESCAN_DELAY())
+		if (maybe != NULL || once || IF_RESCAN_DELAY())
 			return maybe;
 		once = 1;
 
@@ -304,7 +304,7 @@ ripv1_mask_net(naddr addr,		/* in network byte order */
 	if (addr == 0)			/* default always has 0 mask */
 		return mask;
 
-	if (ifp != 0 && ifp->int_ripv1_mask != HOST_MASK) {
+	if (ifp != NULL && ifp->int_ripv1_mask != HOST_MASK) {
 		/* If the target network is that of the associated interface
 		 * on which it arrived, then use the netmask of the interface.
 		 */
@@ -329,7 +329,7 @@ ripv1_mask_net(naddr addr,		/* in network byte order */
 
 	/* check special definitions */
 	if (mask == 0) {
-		for (r1p = r1nets; r1p != 0; r1p = r1p->r1net_next) {
+		for (r1p = r1nets; r1p != NULL; r1p = r1p->r1net_next) {
 			if (on_net(addr, r1p->r1net_net, r1p->r1net_match)
 			    && r1p->r1net_mask > mask)
 				mask = r1p->r1net_mask;
@@ -425,7 +425,7 @@ check_remote(struct interface *ifp)
 	    return 1;
 
 	rt = rtfind(ifp->int_addr);
-	if (rt != 0
+	if (rt != NULL 
 	    && rt->rt_ifp != 0
 	    &&on_net(ifp->int_addr,
 		     rt->rt_ifp->int_net, rt->rt_ifp->int_mask))
@@ -497,7 +497,7 @@ ifdel(struct interface *ifp)
 			    && !TRACEACTIONS)
 				LOGERR("setsockopt(MCAST_LEAVE_GROUP RIP)");
 			if (rip_sock_mcast == ifp)
-				rip_sock_mcast = 0;
+				rip_sock_mcast = NULL;
 		}
 		if (ifp->int_rip_sock >= 0) {
 			(void)close(ifp->int_rip_sock);
@@ -906,7 +906,7 @@ ifinit(void)
 		ifp = ifwithname(ifs.int_name, ((ifs.int_state & IS_ALIAS)
 						? ifs.int_addr
 						: 0));
-		if (ifp != 0) {
+		if (ifp != NULL) {
 			ifp->int_state |= IS_CHECKED;
 
 			if (0 != ((ifp->int_if_flags ^ ifs.int_if_flags)
@@ -927,11 +927,11 @@ ifinit(void)
 				trace_act("interface %s has changed",
 					  ifp->int_name);
 				ifdel(ifp);
-				ifp = 0;
+				ifp = NULL;
 			}
 		}
 
-		if (ifp != 0) {
+		if (ifp != NULL) {
 			/* The primary representative of an alias worries
 			 * about how things are working.
 			 */
@@ -1051,7 +1051,7 @@ ifinit(void)
 		 */
 		ifp = check_dup(ifs.int_addr,ifs.int_dstaddr,ifs.int_mask,
 				ifs.int_if_flags);
-		if (ifp != 0) {
+		if (ifp != NULL) {
 			/* Ignore duplicates of itself, caused by having
 			 * IP aliases on the same network.
 			 */
@@ -1154,15 +1154,15 @@ ifinit(void)
 	if (advertise_mhome
 	    || (tot_interfaces > 1
 		&& mhome
-		&& (ifp = ifwithaddr(myaddr, 0, 0)) != 0
+		&& (ifp = ifwithaddr(myaddr, 0, 0)) != NULL
 		&& foundloopback)) {
 		advertise_mhome = 1;
 		rt = rtget(myaddr, HOST_MASK);
-		if (rt != 0) {
+		if (rt != NULL) {
 			if (rt->rt_ifp != ifp
 			    || rt->rt_router != loopaddr) {
 				rtdelete(rt);
-				rt = 0;
+				rt = NULL;
 			} else {
 				loop_rts.rts_ifp = ifp;
 				loop_rts.rts_metric = 0;
@@ -1171,7 +1171,7 @@ ifinit(void)
 					 &loop_rts, 0);
 			}
 		}
-		if (rt == 0) {
+		if (rt == NULL) {
 			loop_rts.rts_ifp = ifp;
 			loop_rts.rts_metric = 0;
 			rtadd(myaddr, HOST_MASK, RS_MHOME, &loop_rts);
@@ -1220,11 +1220,11 @@ ifinit(void)
 			 */
 			del_static(ifp->int_addr, HOST_MASK, 0, 0);
 			rt = rtget(ifp->int_addr, HOST_MASK);
-			if (rt != 0 && rt->rt_router != loopaddr) {
+			if (rt != NULL && rt->rt_router != loopaddr) {
 				rtdelete(rt);
-				rt = 0;
+				rt = NULL;
 			}
-			if (rt != 0) {
+			if (rt != NULL) {
 				if (!(rt->rt_state & RS_LOCAL)
 				    || rt->rt_metric > ifp->int_metric) {
 					ifp1 = ifp;
@@ -1247,16 +1247,17 @@ ifinit(void)
 	}
 
 	/* add the authority routes */
-	for (intnetp = intnets; intnetp!=0; intnetp = intnetp->intnet_next) {
+	for (intnetp = intnets; intnetp != NULL;
+	    intnetp = intnetp->intnet_next) {
 		rt = rtget(intnetp->intnet_addr, intnetp->intnet_mask);
-		if (rt != 0
+		if (rt != NULL
 		    && !(rt->rt_state & RS_NO_NET_SYN)
 		    && !(rt->rt_state & RS_NET_INT)) {
 			rtdelete(rt);
-			rt = 0;
+			rt = NULL;
 		}
-		if (rt == 0) {
-			loop_rts.rts_ifp = 0;
+		if (rt == NULL) {
+			loop_rts.rts_ifp = NULL;
 			loop_rts.rts_metric = intnetp->intnet_metric-1;
 			rtadd(intnetp->intnet_addr, intnetp->intnet_mask,
 			      RS_NET_SYN | RS_NET_INT, &loop_rts);
@@ -1281,14 +1282,14 @@ check_net_syn(struct interface *ifp)
 	if (have_ripv1_out || have_ripv1_in) {
 		ifp->int_state |= IS_NEED_NET_SYN;
 		rt = rtget(ifp->int_std_addr, ifp->int_std_mask);
-		if (rt != 0
+		if (rt != NULL
 		    && 0 == (rt->rt_state & RS_NO_NET_SYN)
 		    && (!(rt->rt_state & RS_NET_SYN)
 			|| rt->rt_metric > ifp->int_metric)) {
 			rtdelete(rt);
-			rt = 0;
+			rt = NULL;
 		}
-		if (rt == 0) {
+		if (rt == NULL) {
 			new.rts_ifp = ifp;
 			new.rts_gate = ifp->int_addr;
 			new.rts_router = ifp->int_addr;
@@ -1302,7 +1303,7 @@ check_net_syn(struct interface *ifp)
 
 		rt = rtget(ifp->int_std_addr,
 			   ifp->int_std_mask);
-		if (rt != 0
+		if (rt != NULL
 		    && (rt->rt_state & RS_NET_SYN)
 		    && rt->rt_ifp == ifp)
 			rtbad_sub(rt);
@@ -1357,21 +1358,21 @@ addrouteforif(struct interface *ifp)
 	 */
 	del_static(dst, ifp->int_mask, 0, 0);
 	rt = rtget(dst, ifp->int_mask);
-	if (rt != 0) {
+	if (rt != NULL) {
 		if ((rt->rt_ifp != ifp
 		     || rt->rt_router != ifp->int_addr)
 		    && (!(ifp->int_state & IS_DUP)
 			|| rt->rt_ifp == 0
 			|| (rt->rt_ifp->int_state & IS_BROKE))) {
 			rtdelete(rt);
-			rt = 0;
+			rt = NULL;
 		} else {
 			rtchange(rt, ((rt->rt_state | RS_IF)
 				      & ~(RS_NET_SYN | RS_LOCAL)),
 				 &new, 0);
 		}
 	}
-	if (rt == 0) {
+	if (rt == NULL) {
 		if (ifp->int_transitions++ > 0)
 			trace_act("re-install interface %s",
 				  ifp->int_name);
diff --git a/sbin/routed/input.c b/sbin/routed/input.c
index bc03028..bdf0a8b 100644
--- a/sbin/routed/input.c
+++ b/sbin/routed/input.c
@@ -100,9 +100,9 @@ read_rip(int sock,
 			if (aifp->int_addr == from.sin_addr.s_addr)
 				break;
 		}
-		if (aifp == 0) {
+		if (aifp == NULL) {
 			aifp = ifwithname(inbuf.ifname, 0);
-			if (aifp == 0) {
+			if (aifp == NULL) {
 				msglim(&bad_name, from.sin_addr.s_addr,
 				       "impossible interface name %.*s",
 				       IFNAMSIZ, inbuf.ifname);
@@ -115,13 +115,13 @@ read_rip(int sock,
 				/* If it came via the wrong interface, do not
 				 * trust it.
 				 */
-				aifp = 0;
+				aifp = NULL;
 			}
 		}
 #else
 		aifp = iflookup(from.sin_addr.s_addr);
 #endif
-		if (sifp == 0)
+		if (sifp == NULL)
 			sifp = aifp;
 
 		input(&from, sifp, aifp, &inbuf.pbuf.rip, cc);
@@ -148,19 +148,19 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 	struct interface *ifp1;
 	naddr gate, mask, v1_mask, dst, ddst_h = 0;
 	struct auth *ap;
-	struct tgate *tg = 0;
+	struct tgate *tg = NULL;
 	struct tgate_net *tn;
 	int i, j;
 
 	/* Notice when we hear from a remote gateway
 	 */
-	if (aifp != 0
+	if (aifp != NULL
 	    && (aifp->int_state & IS_REMOTE))
 		aifp->int_act_time = now.tv_sec;
 
 	trace_rip("Recv", "from", from, sifp, rip, cc);
 
-	if (sifp == 0) {
+	if (sifp == NULL) {
 		trace_pkt("    discard a request from an indirect router"
 		    " (possibly an attack)");
 		return;
@@ -206,7 +206,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 	case RIPCMD_REQUEST:
 		/* For mere requests, be a little sloppy about the source
 		 */
-		if (aifp == 0)
+		if (aifp == NULL)
 			aifp = sifp;
 
 		/* Are we talking to ourself or a remote gateway?
@@ -233,7 +233,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 			 * the router does not depend on us.
 			 */
 			if (rip_sock < 0
-			    || (aifp != 0
+			    || (aifp != NULL
 				&& IS_RIP_OUT_OFF(aifp->int_state))) {
 				trace_pkt("    discard request while RIP off");
 				return;
@@ -263,20 +263,20 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 		}
 
 		if (rip->rip_vers == RIPv2
-		    && (aifp == 0 || (aifp->int_state & IS_NO_RIPV1_OUT))) {
+		    && (aifp == NULL || (aifp->int_state & IS_NO_RIPV1_OUT))) {
 			v12buf.buf->rip_vers = RIPv2;
 			/* If we have a secret but it is a cleartext secret,
 			 * do not disclose our secret unless the other guy
 			 * already knows it.
 			 */
 			ap = find_auth(aifp);
-			if (ap != 0 && ap->type == RIP_AUTH_PW
+			if (ap != NULL && ap->type == RIP_AUTH_PW
 			    && n->n_family == RIP_AF_AUTH
 			    && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
-				ap = 0;
+				ap = NULL;
 		} else {
 			v12buf.buf->rip_vers = RIPv1;
-			ap = 0;
+			ap = NULL;
 		}
 		clr_ws_buf(&v12buf, ap);
 
@@ -308,7 +308,8 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 					if ((aifp != NULL && insecure > 0) ||
 					    (aifp == NULL && insecure > 1))
 						supply(from, aifp, OUT_QUERY, 0,
-						       rip->rip_vers, ap != 0);
+						       rip->rip_vers,
+						       ap != NULL);
 					else
 						trace_pkt("Warning: "
 						    "possible attack detected");
@@ -323,7 +324,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 				 * to keep an unwary host that is just starting
 				 * from picking us as a router.
 				 */
-				if (aifp == 0) {
+				if (aifp == NULL) {
 					trace_pkt("ignore distant router");
 					return;
 				}
@@ -347,7 +348,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 					v12buf.n->n_family = RIP_AF_INET;
 					v12buf.n->n_dst = RIP_DEFAULT;
 					i = aifp->int_d_metric;
-					if (0 != (rt = rtget(RIP_DEFAULT, 0))) {
+					if (NULL != (rt = rtget(RIP_DEFAULT, 0))) {
 					    j = (rt->rt_metric
 						 +aifp->int_metric
 						 +aifp->int_adj_outmetric
@@ -369,7 +370,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 				supply(from, aifp, OUT_UNICAST, 0,
 				       (aifp->int_state & IS_NO_RIPV1_OUT)
 				       ? RIPv2 : RIPv1,
-				       ap != 0);
+				       ap != NULL);
 				return;
 			}
 
@@ -411,7 +412,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 
 			if (v12buf.buf->rip_vers != RIPv1)
 				v12buf.n->n_mask = mask;
-			if (rt == 0) {
+			if (rt == NULL) {
 				/* we do not have the answer */
 				v12buf.n->n_metric = HOPCNT_INFINITY;
 			} else {
@@ -433,7 +434,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 				if (v12buf.buf->rip_vers != RIPv1) {
 					v12buf.n->n_tag = rt->rt_tag;
 					v12buf.n->n_mask = mask;
-					if (aifp != 0
+					if (aifp != NULL
 					    && on_net(rt->rt_gate,
 						      aifp->int_net,
 						      aifp->int_mask)
@@ -451,7 +452,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 
 		/* Send the answer about specific routes.
 		 */
-		if (ap != 0 && ap->type == RIP_AUTH_MD5)
+		if (ap != NULL && ap->type == RIP_AUTH_MD5)
 			end_md5_auth(&v12buf, ap);
 
 		if (from->sin_port != htons(RIP_PORT)) {
@@ -486,7 +487,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 			       naddr_ntoa(FROM_NADDR));
 			return;
 		}
-		if (aifp == 0) {
+		if (aifp == NULL) {
 			msglog("trace command from unknown router %s",
 			       naddr_ntoa(FROM_NADDR));
 			return;
@@ -543,7 +544,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 		 * via broadcast or point-to-point networks, and from
 		 * those listed in /etc/gateways.
 		 */
-		if (aifp == 0) {
+		if (aifp == NULL) {
 			msglim(&unk_router, FROM_NADDR,
 			       "   discard response from %s"
 			       " via unexpected interface",
@@ -588,7 +589,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 			tg = tgates;
 			while (tg->tgate_addr != FROM_NADDR) {
 				tg = tg->tgate_next;
-				if (tg == 0) {
+				if (tg == NULL) {
 					trace_pkt("    discard RIP response"
 						  " from untrusted router %s",
 						  naddr_ntoa(FROM_NADDR));
@@ -733,7 +734,7 @@ input(struct sockaddr_in *from,		/* received from this IP address */
 			 * of the defense against RS_NET_SYN.
 			 */
 			if (have_ripv1_out
-			    && (((rt = rtget(dst,mask)) == 0
+			    && (((rt = rtget(dst,mask)) == NULL
 				 || !(rt->rt_state & RS_NET_SYN)))
 			    && (v1_mask = ripv1_mask_net(dst,0)) > mask) {
 				ddst_h = v1_mask & -v1_mask;
@@ -798,7 +799,7 @@ input_route(naddr dst,			/* network order */
 	 * If our interface is broken, switch to using the other guy.
 	 */
 	ifp1 = ifwithaddr(dst, 1, 1);
-	if (ifp1 != 0
+	if (ifp1 != NULL
 	    && (!(ifp1->int_state & IS_BROKE)
 		|| (ifp1->int_state & IS_PASSIVE)))
 		return;
@@ -809,7 +810,7 @@ input_route(naddr dst,			/* network order */
 
 	/* Consider adding the route if we do not already have it.
 	 */
-	if (rt == 0) {
+	if (rt == NULL) {
 		/* Ignore unknown routes being poisoned.
 		 */
 		if (new->rts_metric == HOPCNT_INFINITY)
@@ -817,7 +818,7 @@ input_route(naddr dst,			/* network order */
 
 		/* Ignore the route if it points to us */
 		if (n->n_nhop != 0
-		    && 0 != ifwithaddr(n->n_nhop, 1, 0))
+		    && ifwithaddr(n->n_nhop, 1, 0) != NULL)
 			return;
 
 		/* If something has not gone crazy and tried to fill
@@ -915,7 +916,7 @@ input_route(naddr dst,			/* network order */
 		 * Ignore the route if it points to us.
 		 */
 		if (n->n_nhop != 0
-		    && 0 != ifwithaddr(n->n_nhop, 1, 0))
+		    && NULL != ifwithaddr(n->n_nhop, 1, 0))
 			return;
 
 		/* the loop above set rts0=worst spare */
diff --git a/sbin/routed/main.c b/sbin/routed/main.c
index 5ebd7ec..226fe70 100644
--- a/sbin/routed/main.c
+++ b/sbin/routed/main.c
@@ -752,7 +752,7 @@ rip_on(struct interface *ifp)
 	 * multicasts for this interface.
 	 */
 	if (rip_sock >= 0) {
-		if (ifp != 0)
+		if (ifp != NULL)
 			rip_mcast_on(ifp);
 		return;
 	}
@@ -778,7 +778,7 @@ rip_on(struct interface *ifp)
 		}
 
 		rip_sock = get_rip_sock(INADDR_ANY, 1);
-		rip_sock_mcast = 0;
+		rip_sock_mcast = NULL;
 
 		/* Do not advertise anything until we have heard something
 		 */
@@ -791,7 +791,7 @@ rip_on(struct interface *ifp)
 		}
 		ifinit_timer.tv_sec = now.tv_sec;
 
-	} else if (ifp != 0
+	} else if (ifp != NULL
 		   && !(ifp->int_state & IS_REMOTE)
 		   && ifp->int_rip_sock < 0) {
 		/* RIP is off, so ensure there are sockets on which
@@ -811,7 +811,7 @@ rtmalloc(size_t size,
 	 const char *msg)
 {
 	void *p = malloc(size);
-	if (p == 0)
+	if (p == NULL)
 		logbad(1,"malloc(%lu) failed in %s", (u_long)size, msg);
 	return p;
 }
@@ -871,7 +871,7 @@ msglog(const char *p, ...)
 	va_start(args, p);
 	vsyslog(LOG_ERR, p, args);
 	va_end(args);
-	if (ftrace != 0) {
+	if (ftrace != NULL) {
 		if (ftrace == stdout)
 			(void)fputs("routed: ", ftrace);
 		va_start(args, p);
@@ -906,7 +906,7 @@ msglim(struct msg_limit *lim, naddr addr, const char *p, ...)
 			/* Reuse a slot at most once every 10 minutes.
 			 */
 			if (lim->reuse > now.tv_sec) {
-				ms = 0;
+				ms = NULL;
 			} else {
 				ms = ms1;
 				lim->reuse = now.tv_sec + 10*60;
@@ -918,13 +918,13 @@ msglim(struct msg_limit *lim, naddr addr, const char *p, ...)
 			 * most once an hour.
 			 */
 			if (ms->until > now.tv_sec)
-				ms = 0;
+				ms = NULL;
 			break;
 		}
 		if (ms->until < ms1->until)
 			ms = ms1;
 	}
-	if (ms != 0) {
+	if (ms != NULL) {
 		ms->addr = addr;
 		ms->until = now.tv_sec + 60*60;	/* 60 minutes */
 
@@ -937,7 +937,7 @@ msglim(struct msg_limit *lim, naddr addr, const char *p, ...)
 	}
 
 	/* always display the message if tracing */
-	if (ftrace != 0) {
+	if (ftrace != NULL) {
 		va_start(args, p);
 		(void)vfprintf(ftrace, p, args);
 		va_end(args);
diff --git a/sbin/routed/output.c b/sbin/routed/output.c
index c2ed468..e3bee7a 100644
--- a/sbin/routed/output.c
+++ b/sbin/routed/output.c
@@ -164,7 +164,7 @@ output(enum output_type type,
 					LOGERR("setsockopt(rip_sock, "
 					       "IP_MULTICAST_IF)");
 					errno = serrno;
-					ifp = 0;
+					ifp = NULL;
 					return -1;
 				}
 				rip_sock_mcast = ifp;
@@ -187,11 +187,11 @@ output(enum output_type type,
 	res = sendto(soc, buf, size, flags,
 		     (struct sockaddr *)&osin, sizeof(osin));
 	if (res < 0
-	    && (ifp == 0 || !(ifp->int_state & IS_BROKE))) {
+	    && (ifp == NULL || !(ifp->int_state & IS_BROKE))) {
 		serrno = errno;
 		msglog("%s sendto(%s%s%s.%d): %s", msg,
-		       ifp != 0 ? ifp->int_name : "",
-		       ifp != 0 ? ", " : "",
+		       ifp != NULL ? ifp->int_name : "",
+		       ifp != NULL ? ", " : "",
 		       inet_ntoa(osin.sin_addr),
 		       ntohs(osin.sin_port),
 		       strerror(errno));
@@ -214,10 +214,10 @@ find_auth(struct interface *ifp)
 	int i;
 
 
-	if (ifp == 0)
+	if (ifp == NULL)
 		return 0;
 
-	res = 0;
+	res = NULL;
 	ap = ifp->int_auth;
 	for (i = 0; i < MAX_AUTH_KEYS; i++, ap++) {
 		/* stop looking after the last key */
@@ -230,13 +230,13 @@ find_auth(struct interface *ifp)
 
 		if ((u_long)ap->end < (u_long)clk.tv_sec) {
 			/* note best expired password as a fall-back */
-			if (res == 0 || (u_long)ap->end > (u_long)res->end)
+			if (res == NULL || (u_long)ap->end > (u_long)res->end)
 				res = ap;
 			continue;
 		}
 
 		/* note key with the best future */
-		if (res == 0 || (u_long)res->end < (u_long)ap->end)
+		if (res == NULL || (u_long)res->end < (u_long)ap->end)
 			res = ap;
 	}
 	return res;
@@ -255,7 +255,7 @@ clr_ws_buf(struct ws_buf *wb,
 
 	/* (start to) install authentication if appropriate
 	 */
-	if (ap == 0)
+	if (ap == NULL)
 		return;
 
 	na = (struct netauth*)wb->n;
@@ -317,11 +317,11 @@ supply_write(struct ws_buf *wb)
 	case NO_OUT_RIPV2:
 		break;
 	default:
-		if (ws.a != 0 && ws.a->type == RIP_AUTH_MD5)
+		if (ws.a != NULL && ws.a->type == RIP_AUTH_MD5)
 			end_md5_auth(wb,ws.a);
 		if (output(wb->type, &ws.to, ws.ifp, wb->buf,
 			   ((char *)wb->n - (char*)wb->buf)) < 0
-		    && ws.ifp != 0)
+		    && ws.ifp != NULL)
 			if_sick(ws.ifp);
 		ws.npackets++;
 		break;
@@ -587,7 +587,7 @@ walk_supply(struct radix_node *rn,
 	 * to say every 30 seconds to help detect broken Ethernets or
 	 * other interfaces where one packet every 30 seconds costs nothing.
 	 */
-	if (ws.ifp != 0
+	if (ws.ifp != NULL
 	    && !(ws.state & WS_ST_QUERY)
 	    && (ws.state & WS_ST_TO_ON_NET)
 	    && (!(RT->rt_state & RS_IF)
@@ -680,7 +680,7 @@ supply(struct sockaddr_in *dst,
 	ws.to_std_mask = std_mask(ws.to.sin_addr.s_addr);
 	ws.to_std_net = ntohl(ws.to.sin_addr.s_addr) & ws.to_std_mask;
 
-	if (ifp != 0) {
+	if (ifp != NULL) {
 		ws.to_mask = ifp->int_mask;
 		ws.to_net = ifp->int_net;
 		if (on_net(ws.to.sin_addr.s_addr, ws.to_net, ws.to_mask))
@@ -698,7 +698,7 @@ supply(struct sockaddr_in *dst,
 	if (flash)
 		ws.state |= WS_ST_FLASH;
 
-	if ((ws.ifp = ifp) == 0) {
+	if ((ws.ifp = ifp) == NULL) {
 		ws.metric = 1;
 	} else {
 		/* Adjust the advertised metric by the outgoing interface
@@ -739,18 +739,18 @@ supply(struct sockaddr_in *dst,
 		if ((ws.state & WS_ST_QUERY)
 		    || !(ws.state & WS_ST_TO_ON_NET)) {
 			ws.state |= (WS_ST_AG | WS_ST_SUPER_AG);
-		} else if (ifp == 0 || !(ifp->int_state & IS_NO_AG)) {
+		} else if (ifp == NULL || !(ifp->int_state & IS_NO_AG)) {
 			ws.state |= WS_ST_AG;
 			if (type != OUT_BROADCAST
-			    && (ifp == 0
+			    && (ifp == NULL
 				|| !(ifp->int_state & IS_NO_SUPER_AG)))
 				ws.state |= WS_ST_SUPER_AG;
 		}
 	}
 
 	ws.a = (vers == RIPv2) ? find_auth(ifp) : 0;
-	if (!passwd_ok && ws.a != 0 && ws.a->type == RIP_AUTH_PW)
-		ws.a = 0;
+	if (!passwd_ok && ws.a != NULL && ws.a->type == RIP_AUTH_PW)
+		ws.a = NULL;
 	clr_ws_buf(&v12buf,ws.a);
 	clr_ws_buf(&v2buf,ws.a);
 
@@ -758,7 +758,7 @@ supply(struct sockaddr_in *dst,
 	 * a better, real default route.
 	 */
 	if (supplier && (def_metric = ifp->int_d_metric) != 0) {
-		if (0 == (rt = rtget(RIP_DEFAULT, 0))
+		if ((rt = rtget(RIP_DEFAULT, 0)) == NULL 
 		    || rt->rt_metric+ws.metric >= def_metric) {
 			ws.state |= WS_ST_DEFAULT;
 			ag_check(0, 0, 0, 0, def_metric, def_metric,
diff --git a/sbin/routed/parms.c b/sbin/routed/parms.c
index d5313e0..482b461 100644
--- a/sbin/routed/parms.c
+++ b/sbin/routed/parms.c
@@ -60,7 +60,7 @@ get_parms(struct interface *ifp)
 
 	/* get all relevant parameters
 	 */
-	for (parmp = parms; parmp != 0; parmp = parmp->parm_next) {
+	for (parmp = parms; parmp != NULL; parmp = parmp->parm_next) {
 		if (parmp->parm_name[0] == '\0'
 		    || !strcmp(ifp->int_name, parmp->parm_name)
 		    || (parmp->parm_name[0] == '\n'
@@ -178,7 +178,7 @@ gwkludge(void)
 
 
 	fp = fopen(_PATH_GATEWAYS, "r");
-	if (fp == 0)
+	if (fp == NULL)
 		return;
 
 	if (0 > fstat(fileno(fp), &sb)) {
@@ -208,7 +208,7 @@ gwkludge(void)
 			cp = parse_parms(lptr,
 					 (sb.st_uid == 0
 					  && !(sb.st_mode&(S_IRWXG|S_IRWXO))));
-			if (cp != 0)
+			if (cp != NULL)
 				msglog("%s in line %d of "_PATH_GATEWAYS,
 				       cp, lnum);
 			continue;
@@ -315,7 +315,7 @@ gwkludge(void)
 			state |= IS_NO_RIP;
 
 		ifp = check_dup(gate,dst,netmask,state);
-		if (ifp != 0) {
+		if (ifp != NULL) {
 			msglog("duplicate "_PATH_GATEWAYS" entry \"%s\"",lptr);
 			continue;
 		}
@@ -419,7 +419,7 @@ exit:
 		return -1;
 
 	*buf = '\0';			/* terminate copy of token */
-	if (delimp != 0)
+	if (delimp != NULL)
 		*delimp = c;		/* return delimiter */
 	*linep = pc-1;			/* say where we ended */
 	return 0;
@@ -521,14 +521,14 @@ get_passwd(char *tgt,
 
 		if (delim == '|') {
 			val0 = ++val;
-			if (0 != (p = parse_ts(&k.start,&val,val0,&delim,
-					       buf,sizeof(buf))))
+			if (NULL != (p = parse_ts(&k.start,&val,val0,&delim,
+						  buf,sizeof(buf))))
 				return p;
 			if (delim != '|')
 				return "missing second timestamp";
 			val0 = ++val;
-			if (0 != (p = parse_ts(&k.end,&val,val0,&delim,
-					       buf,sizeof(buf))))
+			if (NULL != (p = parse_ts(&k.end,&val,val0,&delim,
+						  buf,sizeof(buf))))
 				return p;
 			if ((u_long)k.start > (u_long)k.end) {
 				sprintf(buf,"out of order timestamp %.30s",
@@ -570,7 +570,7 @@ parse_parms(char *line,
 	struct r1net *r1netp;
 	struct tgate *tg;
 	naddr addr, mask;
-	char delim, *val0 = 0, *tgt, *val, *p;
+	char delim, *val0 = NULL, *tgt, *val, *p;
 	const char *msg;
 	char buf[BUFSIZ], buf2[BUFSIZ];
 	int i;
@@ -856,7 +856,7 @@ check_parms(struct parm *new)
 	/* compare with existing sets of parameters
 	 */
 	for (parmpp = &parms;
-	     (parmp = *parmpp) != 0;
+	     (parmp = *parmpp) != NULL;
 	     parmpp = &parmp->parm_next) {
 		if (strcmp(new->parm_name, parmp->parm_name))
 			continue;
@@ -943,7 +943,7 @@ getnet(char *name,
 
 	/* Detect and separate "1.2.3.4/24"
 	 */
-	if (0 != (mname = strrchr(name,'/'))) {
+	if (NULL != (mname = strrchr(name,'/'))) {
 		i = (int)(mname - name);
 		if (i > (int)sizeof(hname)-1)	/* name too long */
 			return 0;
@@ -954,7 +954,7 @@ getnet(char *name,
 	}
 
 	np = getnetbyname(name);
-	if (np != 0) {
+	if (np != NULL) {
 		in.s_addr = (naddr)np->n_net;
 		if (0 == (in.s_addr & 0xff000000))
 			in.s_addr <<= 8;
diff --git a/sbin/routed/radix.c b/sbin/routed/radix.c
index 5365e6d..9ae0876 100644
--- a/sbin/routed/radix.c
+++ b/sbin/routed/radix.c
@@ -169,7 +169,8 @@ rn_lookup(void *v_arg, void *m_arg, struct radix_node_head *head)
 	caddr_t netmask = 0;
 
 	if (m_arg) {
-		if ((x = rn_addmask(m_arg, 1, head->rnh_treetop->rn_off)) == 0)
+		if ((x = rn_addmask(m_arg, 1,
+		    head->rnh_treetop->rn_off)) == NULL)
 			return (0);
 		netmask = x->rn_key;
 	}
@@ -190,7 +191,7 @@ rn_satisfies_leaf(char *trial,
 	char *cplim;
 	int length = min(*(u_char *)cp, *(u_char *)cp2);
 
-	if (cp3 == 0)
+	if (cp3 == NULL)
 		cp3 = rn_ones;
 	else
 		length = min(length, *(u_char *)cp3);
@@ -445,7 +446,7 @@ rn_addmask(void *n_arg, int search, int skip)
 	*addmask_key = last_zeroed = mlen;
 	x = rn_search(addmask_key, rn_masktop);
 	if (Bcmp(addmask_key, x->rn_key, mlen) != 0)
-		x = 0;
+		x = NULL;
 	if (x || search)
 		return (x);
 	x = (struct radix_node *)rtmalloc(max_keylen + 2*sizeof(*x),
@@ -500,7 +501,7 @@ rn_new_radix_mask(struct radix_node *tt,
 	struct radix_mask *m;
 
 	MKGet(m);
-	if (m == 0) {
+	if (m == NULL) {
 		log(LOG_ERR, "Mask for route not entered\n");
 		return (0);
 	}
@@ -523,7 +524,7 @@ rn_addroute(void *v_arg,
 	    struct radix_node treenodes[2])
 {
 	caddr_t v = (caddr_t)v_arg, netmask = (caddr_t)n_arg;
-	struct radix_node *t, *x = 0, *tt;
+	struct radix_node *t, *x = NULL, *tt;
 	struct radix_node *saved_tt, *top = head->rnh_treetop;
 	short b = 0, b_leaf = 0;
 	int keyduplicated;
@@ -538,7 +539,7 @@ rn_addroute(void *v_arg,
 	 * nodes and possibly save time in calculating indices.
 	 */
 	if (netmask)  {
-		if ((x = rn_addmask(netmask, 0, top->rn_off)) == 0)
+		if ((x = rn_addmask(netmask, 0, top->rn_off)) == NULL)
 			return (0);
 		b_leaf = x->rn_b;
 		b = -1 - x->rn_b;
@@ -616,7 +617,7 @@ rn_addroute(void *v_arg,
 		for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_mklist)
 			if (m->rm_b >= b_leaf)
 				break;
-		t->rn_mklist = m; *mp = 0;
+		t->rn_mklist = m; *mp = NULL;
 	}
 on2:
 	/* Add new route to highest possible ancestor's list */
@@ -678,21 +679,21 @@ rn_delete(void *v_arg,
 	vlen =  *(u_char *)v;
 	saved_tt = tt;
 	top = x;
-	if (tt == 0 ||
+	if (tt == NULL ||
 	    Bcmp(v + head_off, tt->rn_key + head_off, vlen - head_off))
 		return (0);
 	/*
 	 * Delete our route from mask lists.
 	 */
 	if (netmask) {
-		if ((x = rn_addmask(netmask, 1, head_off)) == 0)
+		if ((x = rn_addmask(netmask, 1, head_off)) == NULL)
 			return (0);
 		netmask = x->rn_key;
 		while (tt->rn_mask != netmask)
-			if ((tt = tt->rn_dupedkey) == 0)
+			if ((tt = tt->rn_dupedkey) == NULL)
 				return (0);
 	}
-	if (tt->rn_mask == 0 || (saved_m = m = tt->rn_mklist) == 0)
+	if (tt->rn_mask == 0 || (saved_m = m = tt->rn_mklist) == NULL)
 		goto on1;
 	if (tt->rn_flags & RNF_NORMAL) {
 		if (m->rm_leaf != tt || m->rm_refs > 0) {
@@ -721,7 +722,7 @@ rn_delete(void *v_arg,
 			MKFree(m);
 			break;
 		}
-	if (m == 0) {
+	if (m == NULL) {
 		log(LOG_ERR, "rn_delete: couldn't find our annotation\n");
 		if (tt->rn_flags & RNF_NORMAL)
 			return (0); /* Dangling ref to us */
diff --git a/sbin/routed/rdisc.c b/sbin/routed/rdisc.c
index 260f6e0..9cbf957 100644
--- a/sbin/routed/rdisc.c
+++ b/sbin/routed/rdisc.c
@@ -118,7 +118,7 @@ trace_rdisc(const char	*act,
 	n_long *wp, *lim;
 
 
-	if (!TRACEPACKETS || ftrace == 0)
+	if (!TRACEPACKETS || ftrace == NULL)
 		return;
 
 	lastlog();
@@ -310,7 +310,7 @@ rdisc_age(naddr bad_gate)
 		/* If switching from client to server, get rid of old
 		 * default routes.
 		 */
-		if (cur_drp != 0)
+		if (cur_drp != NULL)
 			rdisc_sort();
 		rdisc_adv();
 		return;
@@ -462,7 +462,7 @@ rdisc_sort(void)
 
 	/* Find the best discovered route.
 	 */
-	new_drp = 0;
+	new_drp = NULL;
 	for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
 		if (drp->dr_ts == 0)
 			continue;
@@ -487,7 +487,7 @@ rdisc_sort(void)
 		 * bad routers.
 		 * Avoid sick interfaces.
 		 */
-		if (new_drp == 0
+		if (new_drp == NULL
 		    || (!((new_st ^ drp->dr_ifp->int_state) & IS_SICK)
 			&& (new_pref < drp->dr_pref
 			    || (new_pref == drp->dr_pref
@@ -509,11 +509,11 @@ rdisc_sort(void)
 
 		/* Stop using discovered routes if they are all bad
 		 */
-		if (new_drp == 0) {
+		if (new_drp == NULL) {
 			trace_act("turn off Router Discovery client");
 			rdisc_ok = 0;
 
-			if (rt != 0
+			if (rt != NULL
 			    && (rt->rt_state & RS_RDISC)) {
 				new = rt->rt_spares[0];
 				new.rts_metric = HOPCNT_INFINITY;
@@ -524,7 +524,7 @@ rdisc_sort(void)
 			}
 
 		} else {
-			if (cur_drp == 0) {
+			if (cur_drp == NULL) {
 				trace_act("turn on Router Discovery client"
 					  " using %s via %s",
 					  naddr_ntoa(new_drp->dr_gate),
@@ -546,7 +546,7 @@ rdisc_sort(void)
 			new.rts_router = new_drp->dr_gate;
 			new.rts_metric = HOPCNT_INFINITY-1;
 			new.rts_time = now.tv_sec;
-			if (rt != 0) {
+			if (rt != NULL) {
 				rtchange(rt, rt->rt_state | RS_RDISC, &new, 0);
 			} else {
 				rtadd(RIP_DEFAULT, 0, RS_RDISC, &new);
@@ -588,7 +588,7 @@ parse_ad(naddr from,
 
 	/* ignore pointers to ourself and routes via unreachable networks
 	 */
-	if (ifwithaddr(gate, 1, 0) != 0) {
+	if (ifwithaddr(gate, 1, 0) != NULL) {
 		trace_pkt("    discard Router Discovery Ad pointing at us");
 		return;
 	}
@@ -608,7 +608,7 @@ parse_ad(naddr from,
 		life = 0;
 	}
 
-	for (new_drp = 0, drp = drs; drp < &drs[MAX_ADS]; drp++) {
+	for (new_drp = NULL, drp = drs; drp < &drs[MAX_ADS]; drp++) {
 		/* accept new info for a familiar entry
 		 */
 		if (drp->dr_gate == gate) {
@@ -622,7 +622,7 @@ parse_ad(naddr from,
 		if (drp->dr_ts == 0) {
 			new_drp = drp;	/* use unused entry */
 
-		} else if (new_drp == 0) {
+		} else if (new_drp == NULL) {
 			/* look for an entry worse than the new one to
 			 * reuse.
 			 */
@@ -647,7 +647,7 @@ parse_ad(naddr from,
 	}
 
 	/* forget it if all of the current entries are better */
-	if (new_drp == 0)
+	if (new_drp == NULL)
 		return;
 
 	new_drp->dr_ifp = ifp;
@@ -746,7 +746,7 @@ send_rdisc(union ad_u *p,
 					   sizeof(mreqn))) {
 				LOGERR("setsockopt(rdisc_sock,"
 				       "IP_MULTICAST_IF)");
-				rdisc_sock_mcast = 0;
+				rdisc_sock_mcast = NULL;
 				return;
 			}
 			rdisc_sock_mcast = ifp;
@@ -763,13 +763,13 @@ send_rdisc(union ad_u *p,
 
 	if (0 > sendto(rdisc_sock, p, p_size, flags,
 		       (struct sockaddr *)&rsin, sizeof(rsin))) {
-		if (ifp == 0 || !(ifp->int_state & IS_BROKE))
+		if (ifp == NULL || !(ifp->int_state & IS_BROKE))
 			msglog("sendto(%s%s%s): %s",
-			       ifp != 0 ? ifp->int_name : "",
-			       ifp != 0 ? ", " : "",
+			       ifp != NULL ? ifp->int_name : "",
+			       ifp != NULL ? ", " : "",
 			       inet_ntoa(rsin.sin_addr),
 			       strerror(errno));
-		if (ifp != 0)
+		if (ifp != NULL)
 			if_sick(ifp);
 	}
 }
@@ -920,7 +920,7 @@ ck_icmp(const char *act,
 
 	trace_rdisc(act, from, to, ifp, p, len);
 
-	if (ifp == 0)
+	if (ifp == NULL)
 		trace_pkt("unknown interface for router-discovery %s"
 			  " from %s to %s",
 			  type, naddr_ntoa(from), naddr_ntoa(to));
@@ -981,7 +981,7 @@ read_d(void)
 
 #ifdef USE_PASSIFNAME
 		ifp = ifwithname(buf.ifname, 0);
-		if (ifp == 0)
+		if (ifp == NULL)
 			msglim(&bad_name, from.sin_addr.s_addr,
 			       "impossible rdisc if_ name %.*s",
 			       IFNAMSIZ, buf.ifname);
@@ -994,7 +994,7 @@ read_d(void)
 #endif
 		ifp = ck_icmp("Recv", from.sin_addr.s_addr, ifp,
 			      buf.pkt.ip.ip_dst.s_addr, p, cc);
-		if (ifp == 0)
+		if (ifp == NULL)
 			continue;
 		if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) {
 			trace_pkt("    "
diff --git a/sbin/routed/rtquery/rtquery.c b/sbin/routed/rtquery/rtquery.c
index 1b3a47b..2d9f351 100644
--- a/sbin/routed/rtquery/rtquery.c
+++ b/sbin/routed/rtquery/rtquery.c
@@ -176,7 +176,7 @@ main(int argc,
 			rflag = getnet(optarg, &OMSG.rip_nets[0]);
 			if (!rflag) {
 				struct hostent *hp = gethostbyname(optarg);
-				if (hp == 0) {
+				if (hp == NULL) {
 					fprintf(stderr, "%s: %s:",
 						pgmname, optarg);
 					herror(0);
@@ -353,7 +353,7 @@ trace_loop(char *argv[])
 	}
 
 	res = 1;
-	while (*argv != 0) {
+	while (*argv != NULL) {
 		if (out(*argv++) <= 0)
 			res = 0;
 	}
@@ -417,9 +417,9 @@ query_loop(char *argv[], int argc)
 	}
 
 	/* ask the first (valid) host */
-	seen = 0;
+	seen = NULL;
 	while (0 > out(*argv++)) {
-		if (*argv == 0)
+		if (*argv == NULL)
 			exit(1);
 		answered++;
 	}
@@ -445,13 +445,13 @@ query_loop(char *argv[], int argc)
 			 * because a router might respond with a
 			 * different source address.
 			 */
-			for (sp = seen; sp != 0; sp = sp->next) {
+			for (sp = seen; sp != NULL; sp = sp->next) {
 				if (sp->addr.s_addr == from.sin_addr.s_addr)
 					break;
 			}
-			if (sp == 0) {
+			if (sp == NULL) {
 				sp = malloc(sizeof(*sp));
-				if (sp == 0) {
+				if (sp == NULL) {
 					fprintf(stderr,
 						"rtquery: malloc failed\n");
 					exit(1);
@@ -476,7 +476,7 @@ query_loop(char *argv[], int argc)
 		/* After a pause in responses, probe another host.
 		 * This reduces the intermingling of answers.
 		 */
-		while (*argv != 0 && 0 > out(*argv++))
+		while (*argv != NULL && out(*argv++) < 0)
 			answered++;
 
 		/* continue until no more packets arrive
@@ -520,7 +520,7 @@ out(const char *host)
 #endif
 	if (!inet_aton(host, &router.sin_addr)) {
 		hp = gethostbyname(host);
-		if (hp == 0) {
+		if (hp == NULL) {
 			herror(host);
 			return -1;
 		}
@@ -619,7 +619,7 @@ rip_input(struct sockaddr_in *from,
 	} else {
 		hp = gethostbyaddr((char*)&from->sin_addr,
 				   sizeof(struct in_addr), AF_INET);
-		if (hp == 0) {
+		if (hp == NULL) {
 			printf("%s:",
 			       inet_ntoa(from->sin_addr));
 		} else {
@@ -691,7 +691,7 @@ rip_input(struct sockaddr_in *from,
 				if ((in.s_addr & ~mask) == 0) {
 					np = getnetbyaddr((long)in.s_addr,
 							  AF_INET);
-					if (np != 0)
+					if (np != NULL)
 						name = np->n_name;
 					else if (in.s_addr == 0)
 						name = "default";
@@ -702,7 +702,7 @@ rip_input(struct sockaddr_in *from,
 					hp = gethostbyaddr((char*)&in,
 							   sizeof(in),
 							   AF_INET);
-					if (hp != 0)
+					if (hp != NULL)
 						name = hp->h_name;
 				}
 			}
@@ -770,12 +770,12 @@ rip_input(struct sockaddr_in *from,
 		if (n->n_nhop != 0) {
 			in.s_addr = n->n_nhop;
 			if (nflag)
-				hp = 0;
+				hp = NULL;
 			else
 				hp = gethostbyaddr((char*)&in, sizeof(in),
 						   AF_INET);
 			(void)printf(" nhop=%-15s%s",
-				     (hp != 0) ? hp->h_name : inet_ntoa(in),
+				     (hp != NULL) ? hp->h_name : inet_ntoa(in),
 				     (IMSG.rip_vers == RIPv1) ? " ?" : "");
 		}
 		if (n->n_tag != 0)
@@ -820,7 +820,7 @@ getnet(char *name,
 
 	/* Detect and separate "1.2.3.4/24"
 	 */
-	if (0 != (mname = strrchr(name,'/'))) {
+	if (NULL != (mname = strrchr(name,'/'))) {
 		i = (int)(mname - name);
 		if (i > (int)sizeof(hname)-1)	/* name too long */
 			return 0;
@@ -831,7 +831,7 @@ getnet(char *name,
 	}
 
 	nentp = getnetbyname(name);
-	if (nentp != 0) {
+	if (nentp != NULL) {
 		in.s_addr = nentp->n_net;
 	} else if (inet_aton(name, &in) == 1) {
 		in.s_addr = ntohl(in.s_addr);
@@ -839,7 +839,7 @@ getnet(char *name,
 		return 0;
 	}
 
-	if (mname == 0) {
+	if (mname == NULL) {
 		mask = std_mask(in.s_addr);
 		if ((~mask & in.s_addr) != 0)
 			mask = 0xffffffff;
@@ -910,7 +910,7 @@ parse_quote(char **linep,
 		--lim;
 	}
 exit:
-	if (delimp != 0)
+	if (delimp != NULL)
 		*delimp = c;
 	*linep = pc-1;
 	if (lim != 0)
diff --git a/sbin/routed/table.c b/sbin/routed/table.c
index ec36989..3a30071 100644
--- a/sbin/routed/table.c
+++ b/sbin/routed/table.c
@@ -99,9 +99,9 @@ static struct ag_info ag_slots[NUM_AG_SLOTS], *ag_avail, *ag_corsest, *ag_finest
 /* #define DEBUG_AG */
 #ifdef DEBUG_AG
 #define CHECK_AG() {int acnt = 0; struct ag_info *cag;		\
-	for (cag = ag_avail; cag != 0; cag = cag->ag_fine)	\
+	for (cag = ag_avail; cag != NULL; cag = cag->ag_fine)	\
 		acnt++;						\
-	for (cag = ag_corsest; cag != 0; cag = cag->ag_fine)	\
+	for (cag = ag_corsest; cag != NULL; cag = cag->ag_fine)	\
 		acnt++;						\
 	if (acnt != NUM_AG_SLOTS) {				\
 		(void)fflush(stderr);				\
@@ -139,7 +139,7 @@ ag_out(struct ag_info *ag,
 	 * ensures that the twins are seen before the parent is emitted.
 	 */
 	ag_cors = ag->ag_cors;
-	if (ag_cors != 0
+	if (ag_cors != NULL
 	    && ag_cors->ag_mask == ag->ag_mask<<1
 	    && ag_cors->ag_dst_h == (ag->ag_dst_h & ag_cors->ag_mask)) {
 		ag_cors->ag_state |= ((ag_cors->ag_dst_h == ag->ag_dst_h)
@@ -174,12 +174,12 @@ ag_del(struct ag_info *ag)
 {
 	CHECK_AG();
 
-	if (ag->ag_cors == 0)
+	if (ag->ag_cors == NULL)
 		ag_corsest = ag->ag_fine;
 	else
 		ag->ag_cors->ag_fine = ag->ag_fine;
 
-	if (ag->ag_fine == 0)
+	if (ag->ag_fine == NULL)
 		ag_finest = ag->ag_cors;
 	else
 		ag->ag_fine->ag_cors = ag->ag_cors;
@@ -208,7 +208,7 @@ ag_flush(naddr lim_dst_h,		/* flush routes to here */
 
 
 	for (ag = ag_finest;
-	     ag != 0 && ag->ag_mask >= lim_mask;
+	     ag != NULL && ag->ag_mask >= lim_mask;
 	     ag = ag_cors) {
 		ag_cors = ag->ag_cors;
 
@@ -223,7 +223,7 @@ ag_flush(naddr lim_dst_h,		/* flush routes to here */
 		else for ( ; ; ag_cors = ag_cors->ag_cors) {
 			/* Look for a route that can suppress the
 			 * current route */
-			if (ag_cors == 0) {
+			if (ag_cors == NULL) {
 				/* failed, so output it and look for
 				 * another route to work on
 				 */
@@ -320,9 +320,9 @@ ag_check(naddr	dst,
 
 	/* Search for the right slot in the aggregation table.
 	 */
-	ag_cors = 0;
+	ag_cors = NULL;
 	ag = ag_corsest;
-	while (ag != 0) {
+	while (ag != NULL) {
 		if (ag->ag_mask >= mask)
 			break;
 
@@ -335,7 +335,7 @@ ag_check(naddr	dst,
 		 * This check keeps poor routes (e.g. with large hop counts)
 		 * from preventing suppression of finer routes.
 		 */
-		if (ag_cors != 0
+		if (ag_cors != NULL
 		    && ag->ag_dst_h < dst
 		    && (ag->ag_state & AGS_SUPPRESS)
 		    && ag_cors->ag_pref <= ag->ag_pref
@@ -374,7 +374,7 @@ ag_check(naddr	dst,
 	 * times around this loop, it could be the even twin promoted
 	 * from the even/odd pair of twins of the finer route.
 	 */
-	while (ag != 0
+	while (ag != NULL
 	       && ag->ag_mask == mask
 	       && ((ag->ag_dst_h ^ dst) & (mask<<1)) == 0) {
 
@@ -537,7 +537,7 @@ ag_check(naddr	dst,
 		mask <<= 1;
 		dst &= mask;
 
-		if (ag_cors == 0) {
+		if (ag_cors == NULL) {
 			ag = ag_corsest;
 			break;
 		}
@@ -553,7 +553,7 @@ ag_check(naddr	dst,
 	 * In case we moved toward coarser masks,
 	 * get back where we belong
 	 */
-	if (ag != 0
+	if (ag != NULL
 	    && ag->ag_mask < mask) {
 		ag_cors = ag;
 		ag = ag->ag_fine;
@@ -561,20 +561,20 @@ ag_check(naddr	dst,
 
 	/* Empty the target slot
 	 */
-	if (ag != 0 && ag->ag_mask == mask) {
+	if (ag != NULL && ag->ag_mask == mask) {
 		ag_flush(ag->ag_dst_h, ag->ag_mask, out);
-		ag = (ag_cors == 0) ? ag_corsest : ag_cors->ag_fine;
+		ag = (ag_cors == NULL) ? ag_corsest : ag_cors->ag_fine;
 	}
 
 #ifdef DEBUG_AG
 	(void)fflush(stderr);
-	if (ag == 0 && ag_cors != ag_finest)
+	if (ag == NULL && ag_cors != ag_finest)
 		abort();
-	if (ag_cors == 0 && ag != ag_corsest)
+	if (ag_cors == NULL && ag != ag_corsest)
 		abort();
-	if (ag != 0 && ag->ag_cors != ag_cors)
+	if (ag != NULL && ag->ag_cors != ag_cors)
 		abort();
-	if (ag_cors != 0 && ag_cors->ag_fine != ag)
+	if (ag_cors != NULL && ag_cors->ag_fine != ag)
 		abort();
 	CHECK_AG();
 #endif
@@ -595,12 +595,12 @@ ag_check(naddr	dst,
 	nag->ag_seqno = new_seqno;
 
 	nag->ag_fine = ag;
-	if (ag != 0)
+	if (ag != NULL)
 		ag->ag_cors = nag;
 	else
 		ag_finest = nag;
 	nag->ag_cors = ag_cors;
-	if (ag_cors == 0)
+	if (ag_cors == NULL)
 		ag_corsest = nag;
 	else
 		ag_cors->ag_fine = nag;
@@ -785,11 +785,11 @@ kern_find(naddr dst, naddr mask, struct khash ***ppk)
 {
 	struct khash *k, **pk;
 
-	for (pk = &KHASH(dst,mask); (k = *pk) != 0; pk = &k->k_next) {
+	for (pk = &KHASH(dst,mask); (k = *pk) != NULL; pk = &k->k_next) {
 		if (k->k_dst == dst && k->k_mask == mask)
 			break;
 	}
-	if (ppk != 0)
+	if (ppk != NULL)
 		*ppk = pk;
 	return k;
 }
@@ -801,7 +801,7 @@ kern_add(naddr dst, naddr mask)
 	struct khash *k, **pk;
 
 	k = kern_find(dst, mask, &pk);
-	if (k != 0)
+	if (k != NULL)
 		return k;
 
 	k = (struct khash *)rtmalloc(sizeof(*k), "kern_add");
@@ -833,12 +833,12 @@ kern_check_static(struct khash *k,
 	memset(&new, 0, sizeof(new));
 	new.rts_ifp = ifp;
 	new.rts_gate = k->k_gate;
-	new.rts_router = (ifp != 0) ? ifp->int_addr : loopaddr;
+	new.rts_router = (ifp != NULL) ? ifp->int_addr : loopaddr;
 	new.rts_metric = k->k_metric;
 	new.rts_time = now.tv_sec;
 
 	rt = rtget(k->k_dst, k->k_mask);
-	if (rt != 0) {
+	if (rt != NULL) {
 		if (!(rt->rt_state & RS_STATIC))
 			rtchange(rt, rt->rt_state | RS_STATIC, &new, 0);
 	} else {
@@ -931,9 +931,9 @@ rtm_add(struct rt_msghdr *rtm,
 		    && INFO_AUTHOR(info)->sa_family == AF_INET)
 			ifp = iflookup(S_ADDR(INFO_AUTHOR(info)));
 		else
-			ifp = 0;
+			ifp = NULL;
 		if (supplier
-		    && (ifp == 0 || !(ifp->int_state & IS_REDIRECT_OK))) {
+		    && (ifp == NULL || !(ifp->int_state & IS_REDIRECT_OK))) {
 			/* Routers are not supposed to listen to redirects,
 			 * so delete it if it came via an unknown interface
 			 * or the interface does not have special permission.
@@ -972,7 +972,7 @@ rtm_add(struct rt_msghdr *rtm,
 	 * Find the interface toward the gateway.
 	 */
 	ifp = iflookup(k->k_gate);
-	if (ifp == 0)
+	if (ifp == NULL)
 		msglog("static route %s --> %s impossibly lacks ifp",
 		       addrname(S_ADDR(INFO_DST(info)), mask, 0),
 		       naddr_ntoa(k->k_gate));
@@ -1011,7 +1011,7 @@ get_info_gate(struct sockaddr **sap,
 	struct sockaddr_dl *sdl = (struct sockaddr_dl *)*sap;
 	struct interface *ifp;
 
-	if (sdl == 0)
+	if (sdl == NULL)
 		return 0;
 	if ((sdl)->sdl_family == AF_INET)
 		return 1;
@@ -1019,7 +1019,7 @@ get_info_gate(struct sockaddr **sap,
 		return 0;
 
 	ifp = ifwithindex(sdl->sdl_index, 1);
-	if (ifp == 0)
+	if (ifp == NULL)
 		return 0;
 
 	rsin->sin_addr.s_addr = ifp->int_addr;
@@ -1052,7 +1052,7 @@ flush_kern(void)
 
 
 	for (i = 0; i < KHASH_SIZE; i++) {
-		for (k = khash_bins[i]; k != 0; k = k->k_next) {
+		for (k = khash_bins[i]; k != NULL; k = k->k_next) {
 			k->k_state |= KS_CHECK;
 		}
 	}
@@ -1135,7 +1135,7 @@ flush_kern(void)
 	}
 
 	for (i = 0; i < KHASH_SIZE; i++) {
-		for (k = khash_bins[i]; k != 0; k = k->k_next) {
+		for (k = khash_bins[i]; k != NULL; k = k->k_next) {
 			if (k->k_state & KS_CHECK) {
 				msglog("%s --> %s disappeared from kernel",
 				       addrname(k->k_dst, k->k_mask, 0),
@@ -1198,7 +1198,7 @@ read_rt(void)
 		    || m.r.rtm.rtm_type == RTM_DELADDR) {
 			ifp = ifwithindex(m.ifm.ifm_index,
 					  m.r.rtm.rtm_type != RTM_DELADDR);
-			if (ifp == 0)
+			if (ifp == NULL)
 				trace_act("note %s with flags %#x"
 					  " for unknown interface index #%d",
 					  rtm_type_name(m.r.rtm.rtm_type),
@@ -1217,7 +1217,7 @@ read_rt(void)
 			 * off or on.
 			 */
 			if (ifinit_timer.tv_sec-now.tv_sec>=CHECK_BAD_INTERVAL
-			    || ifp == 0
+			    || ifp == NULL
 			    || ((ifp->int_if_flags ^ m.ifm.ifm_flags)
 				& IFF_UP) != 0)
 				ifinit_timer.tv_sec = now.tv_sec;
@@ -1338,7 +1338,7 @@ kern_out(struct ag_info *ag)
 	 */
 	if (ag->ag_metric == HOPCNT_INFINITY) {
 		k = kern_find(htonl(ag->ag_dst_h), ag->ag_mask, 0);
-		if (k == 0)
+		if (k == NULL)
 			return;
 	} else {
 		k = kern_add(htonl(ag->ag_dst_h), ag->ag_mask);
@@ -1495,7 +1495,7 @@ fix_kern(void)
 	ag_flush(0,0,kern_out);
 
 	for (i = 0; i < KHASH_SIZE; i++) {
-		for (pk = &khash_bins[i]; (k = *pk) != 0; ) {
+		for (pk = &khash_bins[i]; (k = *pk) != NULL; ) {
 			/* Do not touch static routes */
 			if (k->k_state & KS_STATIC) {
 				kern_check_static(k,0);
@@ -1569,7 +1569,7 @@ del_static(naddr dst,
 	 * and add a replacement.
 	 */
 	k = kern_find(dst, mask, 0);
-	if (k != 0 && (gate == 0 || k->k_gate == gate)) {
+	if (k != NULL && (gate == 0 || k->k_gate == gate)) {
 		k->k_state &= ~(KS_STATIC | KS_DYNAMIC | KS_CHECK);
 		k->k_state |= KS_DELETE;
 		if (gone) {
@@ -1579,7 +1579,7 @@ del_static(naddr dst,
 	}
 
 	rt = rtget(dst, mask);
-	if (rt != 0 && (rt->rt_state & RS_STATIC))
+	if (rt != NULL && (rt->rt_state & RS_STATIC))
 		rtbad(rt);
 }
 
@@ -1596,7 +1596,7 @@ del_redirects(naddr bad_gate,
 
 
 	for (i = 0; i < KHASH_SIZE; i++) {
-		for (k = khash_bins[i]; k != 0; k = k->k_next) {
+		for (k = khash_bins[i]; k != NULL; k = k->k_next) {
 			if (!(k->k_state & KS_DYNAMIC)
 			    || (k->k_state & KS_STATIC))
 				continue;
@@ -1827,7 +1827,7 @@ rtswitch(struct rt_entry *rt,
 		return;
 
 	/* find the best alternative among the spares */
-	if (rts == 0)
+	if (rts == NULL)
 		rts = rts_better(rt);
 
 	/* Do not bother if it is not worthwhile.
@@ -1856,7 +1856,7 @@ rtdelete(struct rt_entry *rt)
 		trace_add_del("Del", rt);
 
 	k = kern_find(rt->rt_dst, rt->rt_mask, 0);
-	if (k != 0) {
+	if (k != NULL) {
 		k->k_state |= KS_DELETE;
 		need_kern.tv_sec = now.tv_sec;
 	}
@@ -1909,7 +1909,7 @@ rtbad_sub(struct rt_entry *rt)
 	u_int state;
 
 
-	ifp1 = 0;
+	ifp1 = NULL;
 	state = 0;
 
 	if (rt->rt_state & RS_LOCAL) {
@@ -1947,7 +1947,7 @@ rtbad_sub(struct rt_entry *rt)
 
 		/* or if there is an authority route that needs it. */
 		for (intnetp = intnets;
-		     intnetp != 0;
+		     intnetp != NULL;
 		     intnetp = intnetp->intnet_next) {
 			if (intnetp->intnet_addr == rt->rt_dst
 			    && intnetp->intnet_mask == rt->rt_mask) {
@@ -1957,7 +1957,7 @@ rtbad_sub(struct rt_entry *rt)
 		}
 	}
 
-	if (ifp1 != 0 || (state & RS_NET_SYN)) {
+	if (ifp1 != NULL || (state & RS_NET_SYN)) {
 		struct rt_spare new = rt->rt_spares[0];
 		new.rts_ifp = ifp1;
 		rtchange(rt, ((rt->rt_state & ~(RS_NET_SYN|RS_LOCAL)) | state),
@@ -1987,7 +1987,7 @@ walk_bad(struct radix_node *rn,
 	for (i = NUM_SPARES; i != 1; i--) {
 		rts++;
 		if (rts->rts_metric < HOPCNT_INFINITY
-		    && (rts->rts_ifp == 0
+		    && (rts->rts_ifp == NULL
 			|| (rts->rts_ifp->int_state & IS_BROKE)))
 			rts_delete(RT, rts);
 	}
diff --git a/sbin/routed/trace.c b/sbin/routed/trace.c
index 8797e57..fcde2d4 100644
--- a/sbin/routed/trace.c
+++ b/sbin/routed/trace.c
@@ -139,7 +139,7 @@ naddr_ntoa(naddr a)
 const char *
 saddr_ntoa(struct sockaddr *sa)
 {
-	return (sa == 0) ? "?" : naddr_ntoa(S_ADDR(sa));
+	return (sa == NULL) ? "?" : naddr_ntoa(S_ADDR(sa));
 }
 
 
@@ -180,7 +180,7 @@ tmsg(const char *p, ...)
 {
 	va_list args;
 
-	if (ftrace != 0) {
+	if (ftrace != NULL) {
 		lastlog();
 		va_start(args, p);
 		vfprintf(ftrace, p, args);
@@ -200,10 +200,10 @@ trace_close(int zap_stdio)
 	fflush(stdout);
 	fflush(stderr);
 
-	if (ftrace != 0 && zap_stdio) {
+	if (ftrace != NULL && zap_stdio) {
 		if (ftrace != stdout)
 			fclose(ftrace);
-		ftrace = 0;
+		ftrace = NULL;
 		fd = open(_PATH_DEVNULL, O_RDWR);
 		if (isatty(STDIN_FILENO))
 			(void)dup2(fd, STDIN_FILENO);
@@ -220,7 +220,7 @@ trace_close(int zap_stdio)
 void
 trace_flush(void)
 {
-	if (ftrace != 0) {
+	if (ftrace != NULL) {
 		fflush(ftrace);
 		if (ferror(ftrace))
 			trace_off("tracing off: %s", strerror(ferror(ftrace)));
@@ -234,7 +234,7 @@ trace_off(const char *p, ...)
 	va_list args;
 
 
-	if (ftrace != 0) {
+	if (ftrace != NULL) {
 		lastlog();
 		va_start(args, p);
 		vfprintf(ftrace, p, args);
@@ -307,16 +307,16 @@ set_tracefile(const char *filename,
 	 * is already open or if coming from a trusted source, such as
 	 * a signal or the command line.
 	 */
-	if (filename == 0 || filename[0] == '\0') {
-		filename = 0;
-		if (ftrace == 0) {
+	if (filename == NULL || filename[0] == '\0') {
+		filename = NULL;
+		if (ftrace == NULL) {
 			if (inittracename[0] == '\0') {
 				msglog("missing trace file name");
 				return;
 			}
 			fn = inittracename;
 		} else {
-			fn = 0;
+			fn = NULL;
 		}
 
 	} else if (!strcmp(filename,"dump/../table")) {
@@ -351,9 +351,9 @@ set_tracefile(const char *filename,
 		fn = filename;
 	}
 
-	if (fn != 0) {
+	if (fn != NULL) {
 		n_ftrace = fopen(fn, "a");
-		if (n_ftrace == 0) {
+		if (n_ftrace == NULL) {
 			msglog("failed to open trace file \"%s\" %s",
 			       fn, strerror(errno));
 			if (fn == inittracename)
@@ -375,9 +375,9 @@ set_tracefile(const char *filename,
 		dup2(fileno(ftrace), STDERR_FILENO);
 	}
 
-	if (new_tracelevel == 0 || filename == 0)
+	if (new_tracelevel == 0 || filename == NULL)
 		new_tracelevel++;
-	tracelevel_msg(pat, dump != 0 ? dump : (filename != 0));
+	tracelevel_msg(pat, dump != 0 ? dump : (filename != NULL));
 }
 
 
@@ -410,7 +410,7 @@ set_tracelevel(void)
 	/* If tracing entirely off, and there was no tracefile specified
 	 * on the command line, then leave it off.
 	 */
-	if (new_tracelevel > tracelevel && ftrace == 0) {
+	if (new_tracelevel > tracelevel && ftrace == NULL) {
 		if (savetracename[0] != '\0') {
 			set_tracefile(savetracename,sigtrace_pat,0);
 		} else if (inittracename[0] != '\0') {
@@ -563,7 +563,7 @@ trace_bits(const struct bits *tbl,
 		}
 		tbl++;
 	}
-	if (field != 0 && tbl->bits_name != 0) {
+	if (field != 0 && tbl->bits_name != NULL) {
 		if (c)
 			(void)putc(c, ftrace);
 		(void)fprintf(ftrace, tbl->bits_name, field);
@@ -604,7 +604,7 @@ print_rts(struct rt_spare *rts,
 	if (force_metric >= 0)
 		(void)fprintf(ftrace, "metric=%-2d ", rts->rts_metric);
 	if (force_ifp >= 0)
-		(void)fprintf(ftrace, "%s ", (rts->rts_ifp == 0 ?
+		(void)fprintf(ftrace, "%s ", (rts->rts_ifp == NULL ?
 					      "if?" : rts->rts_ifp->int_name));
 	if (force_router > 0
 	    || (force_router == 0 && rts->rts_router != rts->rts_gate))
@@ -628,7 +628,7 @@ void
 trace_if(const char *act,
 	 struct interface *ifp)
 {
-	if (!TRACEACTIONS || ftrace == 0)
+	if (!TRACEACTIONS || ftrace == NULL)
 		return;
 
 	lastlog();
@@ -661,7 +661,7 @@ trace_upslot(struct rt_entry *rt,
 	     struct rt_spare *rts,
 	     struct rt_spare *new)
 {
-	if (!TRACEACTIONS || ftrace == 0)
+	if (!TRACEACTIONS || ftrace == NULL)
 		return;
 
 	if (rts->rts_gate == new->rts_gate
@@ -721,7 +721,7 @@ trace_misc(const char *p, ...)
 {
 	va_list args;
 
-	if (ftrace == 0)
+	if (ftrace == NULL)
 		return;
 
 	lastlog();
@@ -739,7 +739,7 @@ trace_act(const char *p, ...)
 {
 	va_list args;
 
-	if (!TRACEACTIONS || ftrace == 0)
+	if (!TRACEACTIONS || ftrace == NULL)
 		return;
 
 	lastlog();
@@ -757,7 +757,7 @@ trace_pkt(const char *p, ...)
 {
 	va_list args;
 
-	if (!TRACEPACKETS || ftrace == 0)
+	if (!TRACEPACKETS || ftrace == NULL)
 		return;
 
 	lastlog();
@@ -774,7 +774,7 @@ trace_change(struct rt_entry *rt,
 	     struct	rt_spare *new,
 	     const char	*label)
 {
-	if (ftrace == 0)
+	if (ftrace == NULL)
 		return;
 
 	if (rt->rt_metric == new->rts_metric
@@ -813,7 +813,7 @@ trace_change(struct rt_entry *rt,
 void
 trace_add_del(const char * action, struct rt_entry *rt)
 {
-	if (ftrace == 0)
+	if (ftrace == NULL)
 		return;
 
 	lastlog();
@@ -863,7 +863,7 @@ trace_dump(void)
 {
 	struct interface *ifp;
 
-	if (ftrace == 0)
+	if (ftrace == NULL)
 		return;
 	lastlog();
 
@@ -885,7 +885,7 @@ trace_rip(const char *dir1, const char *dir2,
 #	define NA ((struct netauth*)n)
 	int i, seen_route;
 
-	if (!TRACEPACKETS || ftrace == 0)
+	if (!TRACEPACKETS || ftrace == NULL)
 		return;
 
 	lastlog();