is_online() tried the captive test first

Closes #13.

NEWS.md

@@ -1,6 +1,9 @@
 
 # Development version
 
+* `is_online()` now tries the Apple captive test first, because it works better
+  when DNS is not masked, but HTTP is (#13).
+
 # 2.0.0
 
 * New `nsl()` function to perform DNS queries.

R/ping-package.r

@@ -135,9 +135,9 @@ ping_os <- function(destination, continuous, count, timeout) {
 #' Is the computer online?
 #'
 #' Check if the computer is online. It does three tries:
+#' * Retrieve Apple's Captive Portal test page, see [apple_captive_test()].
 #' * Queries myip.opendns.com on OpenDNS, see [my_ip()].
 #' * Retrieves icanhazip.com via HTTPS, see [my_ip()].
-#' * Retrieve Apple's Captive Portal test page, see [apple_captive_test()].
 #' If any of these are successful, it returns `TRUE`.
 #'
 #' @param timeout Timeout for the queries. (Note: it is currently not
@@ -156,17 +156,17 @@ is_online <- function(timeout = 1) {
   on.exit(options(opts), add = TRUE)
 
   tryCatch({
-    my_ip(method = "dns")
-    return(TRUE)
+    if (apple_captive_test()) return(TRUE)
   }, error = function(e) NULL)
 
   tryCatch({
-    my_ip(method = "https")
+    my_ip(method = "dns")
     return(TRUE)
   }, error = function(e) NULL)
 
   tryCatch({
-    if (apple_captive_test()) return(TRUE)
+    my_ip(method = "https")
+    return(TRUE)
   }, error = function(e) NULL)
 
   FALSE