blacklist: add new blacklist reason, ROAM_REQUESTED

This adds a new (less severe) blacklist reason as well as an option
to configure the timeout. This blacklist reason will be used in cases
where a BSS has requested IWD roam elsewhere. At that time a new
blacklist entry will be added which will be used along with some
other criteria to determine if IWD should connect/roam to that BSS
again.

Now that we have multiple blacklist reasons there may be situations
where a blacklist entry already exists but with a different reason.
This is going to be handled by the reason severity. Since we have
just two reasons we will treat a connection failure as most severe
and a roam requested as less severe. This leaves us with two
possible situations:

1. BSS is roam blacklisted, then gets connection blacklisted:
   The reason will be "promoted" to connection blacklisted.

2. BSS is connection blacklisted, then gets roam blacklisted:
   The blacklist request will be ignored

src/blacklist.c

@@ -45,6 +45,7 @@
 
 static uint64_t blacklist_multiplier;
 static uint64_t blacklist_initial_timeout;
+static uint64_t blacklist_roam_initial_timeout;
 static uint64_t blacklist_max_timeout;
 
 struct blacklist_entry {
@@ -66,6 +67,8 @@ static uint64_t get_reason_timeout(enum blacklist_reason reason)
 	switch (reason) {
 	case BLACKLIST_REASON_CONNECT_FAILED:
 		return blacklist_initial_timeout;
+	case BLACKLIST_REASON_ROAM_REQUESTED:
+		return blacklist_roam_initial_timeout;
 	default:
 		l_warn("Unhandled blacklist reason: %u", reason);
 		return 0;
@@ -132,8 +135,25 @@ void blacklist_add_bss(const uint8_t *addr, enum blacklist_reason reason)
 	entry = l_queue_find(blacklist, match_addr, addr);
 
 	if (entry) {
-		uint64_t offset = l_time_diff(entry->added_time,
+		uint64_t offset;
-							entry->expire_time);
+
+		if (reason < entry->reason) {
+			l_debug("Promoting "MAC" blacklist to reason %u",
+					MAC_STR(addr), reason);
+			/* Reset this to the new timeout and reason */
+			entry->reason = reason;
+			entry->added_time = l_time_now();
+			entry->expire_time = l_time_offset(entry->added_time,
+								timeout);
+			return;
+		} else if (reason > entry->reason) {
+			l_debug("Ignoring blacklist extension of "MAC", "
+				"current blacklist status is more severe!",
+				MAC_STR(addr));
+			return;
+		}
+
+		offset = l_time_diff(entry->added_time, entry->expire_time);
 
 		offset *= blacklist_multiplier;
 
@@ -196,6 +216,14 @@ static int blacklist_init(void)
 	/* For easier user configuration the timeout values are in seconds */
 	blacklist_initial_timeout *= L_USEC_PER_SEC;
 
+	if (!l_settings_get_uint64(config, "Blacklist",
+					"InitialRoamRequestedTimeout",
+					&blacklist_roam_initial_timeout))
+		blacklist_roam_initial_timeout = BLACKLIST_DEFAULT_TIMEOUT;
+
+	/* For easier user configuration the timeout values are in seconds */
+	blacklist_roam_initial_timeout *= L_USEC_PER_SEC;
+
 	if (!l_settings_get_uint64(config, "Blacklist",
 					"Multiplier",
 					&blacklist_multiplier))

src/blacklist.h

@@ -26,6 +26,13 @@ enum blacklist_reason {
 	 * connect to it via autoconnect
 	 */
 	BLACKLIST_REASON_CONNECT_FAILED,
+	/*
+	 * This type of blacklist is added when a BSS requests IWD roams
+	 * elsewhere. This is to aid in preventing IWD from roaming/connecting
+	 * back to that BSS in the future unless there are no other "good"
+	 * candidates to connect to.
+	 */
+	BLACKLIST_REASON_ROAM_REQUESTED,
 };
 
 void blacklist_add_bss(const uint8_t *addr, enum blacklist_reason reason);