@@ 37,6 37,18 @@ 
 
 #include "announce-impl.h"
 
+/*
+ * Number of entries per instance to keep around for dedup'ing of QSO
+ * announcements.
+ *
+ * We may receive more than one copy of the same announcement because we may
+ * share the same multiple subnets as the sending instance, or we may have
+ * more than one IP on a subnet.  Either way, we don't want to spam the
+ * callbacks with duplicate QSO announcements.  So, we keep a small circular
+ * buffer of last NUM_QSO_DEDUP uuids that we received for each instance.
+ */
+#define NUM_QSO_DEDUP	4
+
 struct addr {
 	union xsockaddr addr;
 	uint64_t ts;

          
@@ 51,8 63,16 @@ struct instance {
 	/* the bulk of the data lives in the following sub-struct */
 	struct instance_info info;
 
+	struct str *hlog_version;
+
 	struct addr *addrs; /* announcement addresses & times */
 	/* TODO: RPC addresses & ports */
+
+	struct qso_dedup {
+		struct xuuid uuid;
+		enum announce_qso_msg_type type;
+	} qso_dedup[NUM_QSO_DEDUP];
+	size_t qso_dedup_next;
 };
 
 static struct rb_tree instances;

          
@@ 105,15 125,36 @@ static void invoke_callback(struct insta
 			    const struct announce_msg *msg)
 {
 	switch ((enum announce_msg_type) msg->major) {
-		case ANNOUNCE_QSO:
-			if (notify.qso) {
-				struct xuuid uuid;
+		case ANNOUNCE_QSO: {
+			const size_t next = inst->qso_dedup_next;
+			struct xuuid uuid;
+			size_t i;
+
+			if (!notify.qso)
+				return; /* no callback */
+
+			memcpy(uuid.raw, msg->u.qso.uuid, sizeof(uuid));
+
+			for (i = 0; i < ARRAY_LEN(inst->qso_dedup); i++) {
+				struct qso_dedup *d = &inst->qso_dedup[i];
 
-				memcpy(uuid.raw, msg->u.qso.uuid, sizeof(uuid));
+				if (xuuid_compare(&uuid, &d->uuid))
+					continue;
+
+				if (msg->minor != d->type)
+					continue;
+
+				return; /* ignore duplicate */
+			}
 
-				notify.qso(msg->minor, &inst->info, &uuid);
-			}
+			notify.qso(msg->minor, &inst->info, &uuid);
+
+			/* stash uuid & minor type for future dedup matching */
+			inst->qso_dedup[next].uuid = uuid;
+			inst->qso_dedup[next].type = msg->minor;
+			inst->qso_dedup_next = (next + 1) % NUM_QSO_DEDUP;
 			break;
+		}
 		case ANNOUNCE_LOC:
 			if (notify.loc)
 				notify.loc(msg->minor, &inst->info);