tipc: allow closest-first lookup algorithm when legacy address is configured

The removal of an internal structure of the node address has an unwanted
side effect.
- Currently, if a user is sending an anycast message with destination
  domain 0, the tipc_namebl_translate() function will use the 'closest-
  first' algorithm to first look for a node local destination, and only
  when no such is found, will it resort to the cluster global 'round-
  robin' lookup algorithm.
- Current users can get around this, and enforce unconditional use of
  global round-robin by indicating a destination as Z.0.0 or Z.C.0.
- This option disappears when we make the node address flat, since the
  lookup algorithm has no way of recognizing this case. So, as long as
  there are node local destinations, the algorithm will always select
  one of those, and there is nothing the sender can do to change this.

We solve this by eliminating the 'closest-first' option, which was never
a good idea anyway, for non-legacy users, but only for those. To
distinguish between legacy users and non-legacy users we introduce a new
flag 'legacy_addr_format' in struct tipc_core, to be set when the user
configures a legacy-style Z.C.N node address. Hence, when a legacy user
indicates a zero lookup domain 'closest-first' is selected, and in all
other cases we use 'round-robin'.
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/addr.c

@@ -48,15 +48,17 @@ int in_own_node(struct net *net, u32 addr)
 	return (addr == tn->own_addr) || !addr;
 }
 
-int tipc_in_scope(u32 domain, u32 addr)
+bool tipc_in_scope(bool legacy_format, u32 domain, u32 addr)
 {
 	if (!domain || (domain == addr))
-		return 1;
+		return true;
+	if (!legacy_format)
+		return false;
 	if (domain == tipc_cluster_mask(addr)) /* domain <Z.C.0> */
-		return 1;
+		return true;
 	if (domain == (addr & TIPC_ZONE_MASK)) /* domain <Z.0.0> */
-		return 1;
-	return 0;
+		return true;
+	return false;
 }
 
 char *tipc_addr_string_fill(char *string, u32 addr)

net/tipc/addr.h

@@ -67,7 +67,7 @@ static inline int tipc_scope2node(struct net *net, int sc)
 
 u32 tipc_own_addr(struct net *net);
 int in_own_node(struct net *net, u32 addr);
-int tipc_in_scope(u32 domain, u32 addr);
+bool tipc_in_scope(bool legacy_format, u32 domain, u32 addr);
 char *tipc_addr_string_fill(char *string, u32 addr);
 
 #endif

net/tipc/core.h

 /*
  * net/tipc/core.h: Include file for TIPC global declarations
  *
- * Copyright (c) 2005-2006, 2013 Ericsson AB
+ * Copyright (c) 2005-2006, 2013-2018 Ericsson AB
  * Copyright (c) 2005-2007, 2010-2013, Wind River Systems
  * All rights reserved.
  *
@@ -81,6 +81,7 @@ struct tipc_net {
 	u32 own_addr;
 	int net_id;
 	int random;
+	bool legacy_addr_format;
 
 	/* Node table and node list */
 	spinlock_t node_list_lock;

net/tipc/discover.c

@@ -139,6 +139,7 @@ void tipc_disc_rcv(struct net *net, struct sk_buff *skb,
 	struct tipc_net *tn = tipc_net(net);
 	struct tipc_msg *hdr = buf_msg(skb);
 	u16 caps = msg_node_capabilities(hdr);
+	bool legacy = tn->legacy_addr_format;
 	u32 signature = msg_node_sig(hdr);
 	u32 dst = msg_dest_domain(hdr);
 	u32 net_id = msg_bc_netid(hdr);
@@ -165,13 +166,11 @@ void tipc_disc_rcv(struct net *net, struct sk_buff *skb,
 		disc_dupl_alert(b, self, &maddr);
 		return;
 	}
-	/* Domain filter only works if both peers use legacy address format */
-	if (b->domain) {
-		if (!tipc_in_scope(dst, self))
-			return;
-		if (!tipc_in_scope(b->domain, src))
-			return;
-	}
+	if (!tipc_in_scope(legacy, dst, self))
+		return;
+	if (!tipc_in_scope(legacy, b->domain, src))
+		return;
+
 	tipc_node_check_dest(net, src, b, caps, signature,
 			     &maddr, &respond, &dupl_addr);
 	if (dupl_addr)

net/tipc/name_table.c

@@ -499,7 +499,9 @@ struct publication *tipc_nametbl_remove_publ(struct net *net, u32 type,
 u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance,
 			   u32 *destnode)
 {
-	struct tipc_net *tn = net_generic(net, tipc_net_id);
+	struct tipc_net *tn = tipc_net(net);
+	bool legacy = tn->legacy_addr_format;
+	u32 self = tipc_own_addr(net);
 	struct sub_seq *sseq;
 	struct name_info *info;
 	struct publication *publ;
@@ -507,7 +509,7 @@ u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance,
 	u32 port = 0;
 	u32 node = 0;
 
-	if (!tipc_in_scope(*destnode, tn->own_addr))
+	if (!tipc_in_scope(legacy, *destnode, self))
 		return 0;
 
 	rcu_read_lock();
@@ -521,7 +523,7 @@ u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance,
 	info = sseq->info;
 
 	/* Closest-First Algorithm */
-	if (likely(!*destnode)) {
+	if (legacy && !*destnode) {
 		if (!list_empty(&info->local_publ)) {
 			publ = list_first_entry(&info->local_publ,
 						struct publication,

net/tipc/net.c

@@ -240,7 +240,7 @@ int __tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info)
 		addr = nla_get_u32(attrs[TIPC_NLA_NET_ADDR]);
 		if (!addr)
 			return -EINVAL;
-
+		tn->legacy_addr_format = true;
 		tipc_net_start(net, addr);
 	}