RADIUS client: fix extra retry before failover

This commit changes the failover behavior of RADIUS client. Commit
27ebadccfb ("RADIUS client: Cease endless retry for message for
multiple servers") changed the retry logic, causing RADIUS client to
wait RADIUS_CLIENT_NUM_FAILOVER + 1 timeouts before failing over the
first time. Prior to that commit, RADIUS client would wait
RADIUS_CLIENT_NUM_FAILOVER timeouts before each failover. This was
caused by moving the entry->attempts > RADIUS_CLIENT_NUM_FAILOVER
comparison to before the retry attempt, where entry->attempts is
incremented.

The commit in question set entry->attempts in radius_change_server to 1
instead of 0, so RADIUS client would still only wait
RADIUS_CLIENT_NUM_FAILOVER timeouts for subsequent failovers, the same
as the original behavior.

This commit changes the comparison so the initial failover now happens
after waiting RADIUS_CLIENT_NUM_FAILOVER timeouts, as it did originally.
It also changes the RADIUS_CLIENT_MAX_FAILOVER comparison to prevent an
additional attempt to the primary server after the final failover.

Signed-off-by: Ethan Everett <ethan.everett@meraki.net>

src/radius/radius_client.c

@@ -457,7 +457,7 @@ static int radius_client_retransmit(struct radius_client_data *radius,
 	}
 
 	/* retransmit; remove entry if too many attempts */
-	if (entry->accu_attempts > RADIUS_CLIENT_MAX_FAILOVER *
+	if (entry->accu_attempts >= RADIUS_CLIENT_MAX_FAILOVER *
 	    RADIUS_CLIENT_NUM_FAILOVER * num_servers) {
 		wpa_printf(MSG_INFO,
 			   "RADIUS: Removing un-ACKed message due to too many failed retransmit attempts");
@@ -507,7 +507,7 @@ static void radius_client_timer(void *eloop_ctx, void *timeout_ctx)
 		if (now.sec >= entry->next_try) {
 			s = entry->msg_type == RADIUS_AUTH ? radius->auth_sock :
 				radius->acct_sock;
-			if (entry->attempts > RADIUS_CLIENT_NUM_FAILOVER ||
+			if (entry->attempts >= RADIUS_CLIENT_NUM_FAILOVER ||
 			    (s < 0 && entry->attempts > 0)) {
 				if (entry->msg_type == RADIUS_ACCT ||
 				    entry->msg_type == RADIUS_ACCT_INTERIM)
@@ -1116,7 +1116,7 @@ radius_change_server(struct radius_client_data *radius,
 		    (!auth && entry->msg_type != RADIUS_ACCT))
 			continue;
 		entry->next_try = entry->first_try + RADIUS_CLIENT_FIRST_WAIT;
-		entry->attempts = 1;
+		entry->attempts = 0;
 		entry->next_wait = RADIUS_CLIENT_FIRST_WAIT * 2;
 	}