Try to handle CNAMEs and resolve them to A records.

[mail/checkmail.git] / checkmail.pl

diff --git a/checkmail.pl b/checkmail.pl
index 4ea8398..4a0a1ad 100644 (file)
--- a/checkmail.pl
+++ b/checkmail.pl
@@ -9,7 +9,7 @@
 # It can be redistributed and/or modified under the same terms under 
 # which Perl itself is published.
 
-our $VERSION = "0.6.1";
+our $VERSION = "0.6.2";
 
 ################################# Configuration ################################
 # Please fill in a working configuration!
@@ -39,7 +39,7 @@ getopts('Vhqlrf:m:s:e:', \%options);
 
 # -V: display version
 if ($options{'V'}) {
-  print "$myself v $VERSION\nCopyright (c) 2010 Thomas Hochstein <thh\@inter.net>\n";
+  print "$myself v $VERSION\nCopyright (c) 2010-2016 Thomas Hochstein <thh\@inter.net>\n";
   print "This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.\n";
   exit(100);
 };
@@ -67,7 +67,7 @@ if (!$options{'f'} and !$ARGV[0]) {
 };
 
 # -s / -e: override configuration
-$config{'from'} = $options{'s'} if $options{'s'};
+$config{'from'} = $options{'s'} if defined($options{'s'});
 $config{'helo'} = $options{'e'} if $options{'e'};
 
 # -f: open file and read addresses to @adresses
@@ -155,13 +155,26 @@ sub gettargets {
   } else {
     print_dns_result($domain,'MX',undef,$resolver->errorstring,$logr);
     print("    Falling back to A record ...\n") if !($options{'q'});
-       # get A record(s)
+    # get A record(s)
+    # may get CNAMEs instead ...
     if (my $query = $resolver->query($domain,'A','IN')) {
-      print_dns_result($domain,'A',$query->header->ancount,undef,$logr);
+      # save number of answers in a counter
+      my $acount = $query->header->ancount;
       foreach my $rr ($query->answer) {
+        if ($rr->type ne 'A') {
+          # decrease counter if it's not an A record
+          $acount--;
+          # report CNAMEs and don't add them to target list
+          if ($rr->type eq 'CNAME') {
+            printf ("  ~ '%s' is a CNAME for '%s' and will be resolved accordingly. \n",$rr->name,$rr->cname) if !($options{'q'});
+            $$logr .= sprintf("CNAME resolved: %s -> %s\n",$rr->name,$rr->cname);
+          }
+          next;
+        }
         $targets{$rr->address} = 0;
         $$logr .= sprintf("- %s\n",$rr->address);
       };
+      print_dns_result($domain,'A',$acount,undef,$logr);
     # no A record found either; log and fail
     } else {
       print_dns_result($domain,'A',undef,$resolver->errorstring,$logr);
@@ -440,6 +453,7 @@ The hostname to be used for I<HELO> or I<EHLO> in the SMTP dialog.
 =item B<$config{'from'}>
 
 The sender address to be used for I<MAIL FROM> while testing.
+May be empty ('') to set '<>' as MAIL FROM.
 
 =back
 
@@ -460,11 +474,12 @@ them in order of precedence (if necessary). It will run through the
 SMTP dialog until just before the I<DATA> stage, i.e. doing I<EHLO>,
 I<MAIL FROM> and I<RCPT TO>. If no MX is defined, B<checkmail> will
 fall back to the I<example.org> host itself, provided there is at
-least one A record defined in the DNS. If there are neither MX nor A
-records for I<example.org>, mail is not deliverable and B<checkmail>
-will fail accordingly. If no host can be reached, B<checkmail> will
-fail, too. Finally B<checkmail> will fail if mail to the given
-recipient is not accepted by the respective host.
+least one A record defined in the DNS. CNAMEs will be accepted and
+resolved here. If there are neither MX nor A records for
+I<example.org>, mail is not deliverable and B<checkmail> will fail
+accordingly. If no host can be reached, B<checkmail> will fail,
+too. Finally B<checkmail> will fail if mail to the given recipient
+is not accepted by the respective host.
 
 If B<checkmail> fails, you'll not be able to deliver mail to that
 address - at least not using the configured sender address and from