bug#46641: process-tests assume network connection

[Robert Pluim]

>>>>> On Sun, 21 Feb 2021 17:19:12 +0100, Robert Pluim <rpluim@gmail.com> said:

    Robert> Well, the tests in question are asking 'does emacs have a correctly
    Robert> functioning internet connection', so making that a prerequisite for
    Robert> the test seems kind of redundant, but we can do it. But first:
    Robert> disabling my network connection causes dns-query to hang, so 
something
    Robert> like this is needed, I think (we can skip the first hunk if you 
want):

Ah, the wonders of running diff when you haven't tested the result
from a clean emacs. This one actually works.

diff --git a/lisp/net/dns.el b/lisp/net/dns.el
index 2045d4dfca..3ae7469798 100644
--- a/lisp/net/dns.el
+++ b/lisp/net/dns.el
@@ -332,7 +332,7 @@ dns-set-servers
          (setq dns-servers (nreverse dns-servers))))
       (when (executable-find "nslookup")
        (with-temp-buffer
-         (call-process "nslookup" nil t nil "localhost")
+         (call-process "nslookup" nil t nil "-retry=0" "-timeout=2" 
"localhost")
          (goto-char (point-min))
           (when (re-search-forward
           "^Address:[ 
\t]*\\([0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+\\|[[:xdigit:]:]*\\)" nil t)
@@ -496,15 +496,17 @@ dns-query
   "Query a DNS server for NAME of TYPE.
 If FULL, return the entire record returned.
 If REVERSE, look up an IP address."
-  (let ((result nil))
-    (dns-query-asynchronous
-     name
-     (lambda (response)
-       (setq result (list response)))
-     type full reverse)
-    ;; Loop until we get the callback.
-    (while (not result)
-      (sleep-for 0.01))
+  (let* ((result nil)
+         (query-started
+          (dns-query-asynchronous
+           name
+           (lambda (response)
+             (setq result (list response)))
+           type full reverse)))
+    (if query-started
+        ;; Loop until we get the callback.
+        (while (not result)
+          (sleep-for 0.01)))
     (car result)))
 
 (provide 'dns)