From b9560cc74c99e96f97490608b292f23735252aaf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Pokorn=C3=BD?= <jpokorny@redhat.com>
Date: Wed, 14 Sep 2016 22:31:56 +0200
Subject: [PATCH] High: zealous local address matching with the same subnet
 entries

Previously, having booth components on the same subnet could seriously
confuse self-determination of those tolerating fuzziness when doing so
(i.e., not site nor arbitrator).

It would be the case when there are two (or more) addresses sharing the
same network part of the address as one of the actual hosts's addresses
(assigned to one of its interfaces), and the exactly matching one is
listed _after_ at least a single network-part-match-only one ("fuzzy"
match).  Due to the original requirement that any subsequent candidate
would have to beat a running winner in the length of the network prefix,
such exact match could never have been tested and hence missed.
(IOW, algorithm used to search for local, not global maximum in some
circumstances).

Now we allow further examination of the candidate with the same length
of the network prefix as a running winner, which -- moreover -- cannot
be the exact match because now, it terminates the search immediately.
---
 src/transport.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/transport.c b/src/transport.c
index b3e4432..1d620a0 100644
--- a/src/transport.c
+++ b/src/transport.c
@@ -237,15 +237,21 @@ int _find_myself(int family, struct booth_site **mep, int fuzzy_allowed)
 							BOOTH_IPADDR_LEN);
 				}
 
-				/* First try with exact addresses, then optionally with subnet matching. */
-				if (ifa->ifa_prefixlen > address_bits_matched) {
-					find_address(ipaddr,
-							ifa->ifa_family, ifa->ifa_prefixlen,
-							fuzzy_allowed, &me, &address_bits_matched);
-					if (me) {
-						log_debug("found myself at %s (%d bits matched)",
-								site_string(me), address_bits_matched);
+				if (ifa->ifa_prefixlen >= address_bits_matched) {
+					/* First attempt exact match with addresses in the config,
+					   then optionally with subnet matching. */
+					if (find_address(ipaddr,
+							 ifa->ifa_family, ifa->ifa_prefixlen,
+							 fuzzy_allowed, &me, &address_bits_matched)
+							== EXACT_MATCH) {
+						log_debug("found exactly myself at %s (%d bits matched)",
+							  site_string(me), address_bits_matched);
+						break;
 					}
+					if (me)
+						log_debug("running winner to determine myself at %s"
+							  " (%d bits matched)",
+							  site_string(me), address_bits_matched);
 				}
 			}
 			h = NLMSG_NEXT(h, status);
-- 
2.4.11