1 files changed, 149 insertions, 0 deletions
diff --git a/script/handle-mail-replies b/script/handle-mail-replies
new file mode 100755
index 000000000..9b1fb5b29
--- /dev/null
+++ b/script/handle-mail-replies
@@ -0,0 +1,149 @@
+#!/usr/bin/ruby
+
+# Handle email responses sent to us.
+#
+# This script is invoked as a pipe command, i.e. with the raw email message on stdin.
+# - If a message is identified as a permanent bounce, the user is marked as having a
+#   bounced address, and will not be sent any more messages.
+# - If a message is identified as an out-of-office autoreply, it is discarded.
+# - Any other messages are forwarded to config.get("FORWARD_NONBOUNCE_RESPONSES_TO")
+
+
+# We want to avoid loading rails unless we need it, so we start by just loading the
+# config file ourselves.
+$alaveteli_dir = File.join(File.dirname(__FILE__), '..')
+$:.push(File.join($alaveteli_dir, "commonlib", "rblib"))
+load "config.rb"
+MySociety::Config.set_file(File.join($alaveteli_dir, 'config', 'general'), true)
+MySociety::Config.load_default
+
+$:.push(File.join($alaveteli_dir, "vendor", "rails", "actionmailer", "lib", "action_mailer", "vendor", "tmail-1.2.7"))
+require 'tmail'
+
+def main(in_test_mode)
+    Dir.chdir($alaveteli_dir) do
+        raw_message = $stdin.read
+        begin
+            message = TMail::Mail.parse(raw_message)
+        rescue
+            # Error parsing message. Just pass it on, to be on the safe side.
+            forward_on(raw_message) unless in_test_mode
+            return 0
+        end
+        
+        pfas = permanently_failed_addresses(message)
+        if !pfas.empty?
+            if in_test_mode
+                puts pfas
+            else
+                pfas.each do |pfa|
+                    record_bounce(pfa, raw_message)
+                end
+            end
+            return 1
+        end
+        
+        if is_oof? message
+            # Discard out-of-office messages
+            return 2
+        end
+        
+        # Otherwise forward the message on
+        forward_on(raw_message) unless in_test_mode
+        return 0
+    end
+end
+
+def permanently_failed_addresses(message)
+    if message.header_string("Return-Path") == "<>"
+        # Some sort of auto-response
+    
+        # Check for Exim’s X-Failed-Recipients header
+        failed_recipients = message.header_string("X-Failed-Recipients")
+        if !failed_recipients.nil?
+            # The X-Failed-Recipients header contains the email address that failed
+            # Check for the words "This is a permanent error." in the body, to indicate
+            # a permanent failure
+            if message.body =~ /This is a permanent error./
+                return failed_recipients.split(/,\s*/)
+            end
+        end
+        
+        # Next, look for multipart/report
+        if message.content_type == "multipart/report"
+            permanently_failed_recipients = []
+            message.parts.each do |part|
+                if part.content_type == "message/delivery-status"
+                    sections = part.body.split(/\r?\n\r?\n/)
+                    # The first section is a generic header; subsequent sections
+                    # represent a particular recipient. Since we 
+                    sections[1..-1].each do |section|
+                        if section !~ /^Status: (\d)/ || $1 != '5'
+                            # Either we couldn’t find the Status field, or it was a transient failure
+                            break
+                        end
+                        if section =~ /^Final-Recipient: rfc822;(.+)/
+                            permanently_failed_recipients.push($1)
+                        end
+                    end
+                end
+            end
+            if !permanently_failed_recipients.empty?
+                return permanently_failed_recipients
+            end
+        end
+    end
+    
+    return []
+end
+
+def is_oof?(message)
+    # Check for out-of-office
+    
+    if message.header_string("X-POST-MessageClass") == "9; Autoresponder"
+        return true
+    end
+    
+    subject = message.header_string("Subject").downcase
+    if message.header_string("Return-Path") == "<>"
+        if subject.start_with? "out of office: "
+            return true
+        end
+        if subject.start_with? "automatic reply: "
+            return true
+        end
+    end
+    
+    if subject.start_with? "out of office autoreply:"
+        return true
+    end
+    if subject == "out of office"
+        return true
+    end
+    if subject.end_with? "is out of the office"
+        return true
+    end
+    return false
+end
+
+def forward_on(raw_message)
+    forward_non_bounces_to = MySociety::Config.get("FORWARD_NONBOUNCE_RESPONSES_TO", "user-support@localhost")
+    IO.popen("/usr/sbin/sendmail -i #{forward_non_bounces_to}", "w") do |f|
+        f.write(raw_message);
+        f.close;
+    end
+end
+
+def load_rails
+    require File.join('config', 'boot')
+    require RAILS_ROOT + '/config/environment'
+end
+
+def record_bounce(email_address, bounce_message)
+    load_rails
+    User.record_bounce_for_email(email_address, bounce_message)
+end
+
+in_test_mode = (ARGV[0] == "--test")
+status = main(in_test_mode)
+exit(status) if in_test_mode