From a237b44602ff281f4d2a41903ef7ee515080d0d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ask=20Bj=C3=B8rn=20Hansen?= <ask@develooper.com>
Date: Wed, 31 Oct 2001 00:11:29 +0000
Subject: [PATCH] check dns of sending host

rejct mails to unicode@perl.org as no such address exists and it gets
a lot of spam (needs to be moved to an external filter too).

fix bug that screws up the headers.


git-svn-id: https://svn.perl.org/qpsmtpd/trunk@4 958fd67b-6ff1-0310-b445-bb7760255be9
---
 qpsmtpd | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/qpsmtpd b/qpsmtpd
index 891e4c2..df3d833 100755
--- a/qpsmtpd
+++ b/qpsmtpd
@@ -135,6 +135,11 @@ sub mail {
 	  if check_rhsbl($rhsbl, $host);
       }
     }
+
+    if ($from->format ne "<>") {
+      respond(450, "Could not resolve ". $from->host),return 1 unless check_dns($from->host);
+    }
+
     #warn "$$ getting mail from ",$from->format,"\n" if $TRACE;
     respond(250, $from->format . ", sender OK - I always like getting mail from you!");
 
@@ -150,6 +155,7 @@ sub rcpt {
   $rcpt = (Mail::Address->parse($rcpt))[0];
   return respond(501, "could not parse recipient") unless $rcpt;
   return respond(550, "will not relay for ". $rcpt->host) unless check_relay($rcpt->host);
+  return respond(550, "no such mailbox") if lc $rcpt->address eq 'unicode@perl.org';
   push @{$state{transaction}->{rcpt}}, $rcpt;
   respond(250, $rcpt->format . ", recipient OK");
 }
@@ -203,8 +209,8 @@ sub data {
     # Parent
     close MESSAGE_READER  or fault("close msg reader fault"),exit;
     close ENVELOPE_READER or fault("close envelope reader fault"), exit;
-    print MESSAGE_WRITER "Received: from $state{remote_info} (HELO $state{hello_host}) ($state{remote_ip})\r\n";
-    print MESSAGE_WRITER "  by $config{me} (qpsmtpd/$QPsmtpd::VERSION) with SMTP; ", scalar gmtime, " -0000\r\n";
+    print MESSAGE_WRITER "Received: from $state{remote_info} (HELO $state{hello_host}) ($state{remote_ip})\n";
+    print MESSAGE_WRITER "  by $config{me} (qpsmtpd/$QPsmtpd::VERSION) with SMTP; ", scalar gmtime, " -0000\n";
     print MESSAGE_WRITER $buffer;
     close MESSAGE_WRITER;
 
@@ -296,6 +302,24 @@ sub check_dnsbl {
   return "";
 }
 
+sub check_dns {
+  my $host = shift;
+  my $res = new Net::DNS::Resolver;
+  return 1 if mx($res, $host);
+  my $query = $res->search($host);
+  if ($query) {
+    foreach my $rr ($query->answer) {
+      warn "rr->type ". $rr->type;
+      return 1 if $rr->type eq "A" or $rr->type eq "MX";
+    }
+  }
+  else {
+    warn "$$ query for $host failed: ", $res->errorstring, "\n"
+      unless $res->errorstring eq "NXDOMAIN";
+  }
+  return 0;
+}
+
 
 sub check_relay {
   my $host = lc shift;