When following redirects, the plugin supported 'Location:' header fields

which spanned multiple lines.  However, it was not checked whether extra
lines are preceeded with white space, which could lead to the following
header field name being interpreted as the value of the 'Location:'
field if the latter was empty for some reason.


git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1741 f882894a-f735-0410-b71e-b25c423dba1c

plugins/check_http.c

@@ -1099,7 +1099,19 @@ redir (char *pos, char *status_line)
     }
 
     pos += i;
-    pos += strspn (pos, " \t\r\n");
+    pos += strspn (pos, " \t");
+
+    /*
+     * RFC 2616 (4.2):  ``Header fields can be extended over multiple lines by
+     * preceding each extra line with at least one SP or HT.''
+     */
+    for (; (i = strspn (pos, "\r\n")); pos += i) {
+      pos += i;
+      if (!(i = strspn (pos, " \t"))) {
+        die (STATE_UNKNOWN, _("HTTP UNKNOWN - Empty redirect location%s\n"),
+             display_html ? "</A>" : "");
+      }
+    }
 
     url = realloc (url, strcspn (pos, "\r\n") + 1);
     if (url == NULL)