commit 5425b3f0470e93a44529f3100be771616135b530
Author: Marc Dequènes (Duck) <Duck@DuckCorp.org>
Date:   Sat Mar 7 18:45:29 2009 +0100

    [evol] separate signed mail processing from commands extracting, and improved order

diff --git a/lib/cyborghood/mail.rb b/lib/cyborghood/mail.rb
index e542893..bff5595 100644
--- a/lib/cyborghood/mail.rb
+++ b/lib/cyborghood/mail.rb
@@ -38,12 +38,31 @@ require 'digest/md5'
 # This class handles RFC3156 signed messages, validates them, and extract orders properly.
 # Encrypted content are not implemented yet.
 module CyborgHood
+  class Order
+    attr_accessor :ok, :message, :system_message, :user, :commands, :references
+    attr_writer = :warn_sender
+
+    def initialize(ok, message = nil, system_message = nil)
+      @ok = ok
+      @message = message
+      @system_message = system_message
+    end
+
+    def warn_sender
+      # send reply message if user is identified or in selected situations
+      # (@warn_sender acts as an override)
+      @warn_sender || @user
+    end
+  end
+
   class Mail < Delegator
     include ActionMailer::Quoting
     include ActionMailer::Utils
 
     MAX_DRIFT_TIME = 600
 
+    attr_accessor :user
+
     def initialize(msg = nil)
       @config = Config.instance
 
@@ -62,13 +81,15 @@ module CyborgHood
 
     def parse
       if is_marked?
-        logger.info "Replay detected"
-        return nil
+        return Order.new(false, "Replay detected.")
       end
 
       return parse_signed() if is_pgp_signed?
       return parse_encrypted() if is_pgp_encrypted?
-      {:ok => false, :msg => "mail not RFC3156 compliant"}.to_ostruct
+      # don't parse commands if user is not identified
+      return parse_plain if self.user
+
+      Order.new(false, "Mail not RFC3156 compliant.")
     end
 
     def create_reply
@@ -76,6 +97,7 @@ module CyborgHood
       tmail_reply.from_addrs = TMail::Address.parse(@config.mail.from_address || self.to.first)
       reply = self.class.new(tmail_reply.to_s)
       reply.set_custom_headers
+      reply.user = self.user
       reply
     end
 
@@ -85,6 +107,7 @@ module CyborgHood
       relay.set_disposition("inline")
       reply.quoted_printable_body = msg
       reply.sign
+      reply.crypt(reply.user.keyFingerPrint) unless reply.user.nil?
       reply
     end
 
@@ -139,79 +162,90 @@ module CyborgHood
 
     private
 
-    def parse_signed
-      order = {:ok => false, :msg => "mail not formatted correctly"}
+    def parse_plain
+      command_txt = nil
+      if multipart?
+        if parts[0].content_type == "text/plain"
+          command_txt = self.parts[0].body
+          refs = self.parts.collect{|p| p.dup }
+        end
+      else
+        command_txt = self.body if self.content_type == "text/plain"
+        refs = []
+      end
+      unless command_txt
+        order = Order.new(false, "Mail does not contain a proper text part for commands.")
+        order.user = self.user
+        return order
+      end
+
+      commands = []
+      command_txt.each_line do |line|
+        line.chomp!
+        sline = line.strip
+        # skip empty lines and comments
+        next if sline == "" or sline[0, 1] == "#"
+        # stop processing when detecting message signature
+        break if line == "-- "
 
+        commands << sline
+      end
+
+      logger.debug "Mail OK"
+      mark_processed(sig_check.timestamp)
+
+      order = Order.new(true)
+      order.user = self.user
+      order.commands = commands
+      order.refs = refs
+    end
+
+    def parse_signed
       sigs_check = verify_pgp_signature()
-      return order.to_ostruct if sigs_check.nil? or sigs_check.size != 1
+      return Order.new(false, "mail not formatted correctly (signed part)") if sigs_check.nil? or sigs_check.size != 1
 
       sig_check = sigs_check.first
-      if sig_check.status == 0
-        logger.info "Mail content was properly signed by key #{sig_check.fingerprint}"
-        user = Person.find_by_fingerprint(sig_check.fingerprint)
-        if user.nil?
-          logger.info "Mail is from an unknown person"
-          order[:msg] = "unknown user"
+      return Order.new(false, "Mail content tampered or badly signed: " + sig_check.to_s) unless sig_check.status == 0
+
+      logger.info "Mail content was properly signed by key #{sig_check.fingerprint}"
+      user = Person.find_by_fingerprint(sig_check.fingerprint)
+      if user.nil?
+        order = Order.new(false, "Mail is from an unknown person.")
+        order.warn_sender = true
+        return order
+      end
+
+      logger.info "Mail is from user #{user.uid} (#{user.cn})"
+      self.user = user
+
+      drift = Time.new.to_i - sig_check.timestamp.to_i
+      logger.debug "Signature drift time: #{drift}"
+      unless drift.abs < MAX_DRIFT_TIME
+        if drift > 0
+          order = Order.new(false, "The signature was made too long ago (check your system clock)." +
+                            " Rejected message to avoid replay attacks.")
+          order.user = self.user
         else
-          logger.info "Mail is from user #{user.uid} (#{user.cn})"
-
-          drift = Time.new.to_i - sig_check.timestamp.to_i
-          logger.debug "Signature drift time: #{drift}"
-          if drift.abs < MAX_DRIFT_TIME
-            signed_content = pgp_signed_part()
-            if signed_content.multipart?
-              if signed_content.parts[0].content_type == "text/plain"
-                command_txt = signed_content.parts[0].body
-                refs = signed_content.parts.collect{|p| p.dup }
-              end
-            else
-              command_txt = signed_content.body if signed_content.content_type == "text/plain"
-              refs = []
-            end
-
-            if command_txt
-              commands = []
-              command_txt.each_line do |line|
-                line.chomp!
-                sline = line.strip
-                # skip empty lines and comments
-                next if sline == "" or sline[0, 1] == "#"
-                # stop processing when detecting message signature
-                break if line == "-- "
-
-                commands << sline
-              end
-
-              logger.debug "Mail OK"
-              mark_processed(sig_check.timestamp)
-              order = {:ok => true, :user => user, :commands => commands, :refs => refs}
-            else
-              order[:user] = user
-              logger.info "Mail does not contain a proper MIME part for commands"
-            end
-          else
-            if drift > 0
-              logger.info "Mail rejected as it may be a replay (signature timestamp is too old)"
-              order = {:ok => false, :user => user, :msg => "The signature was made too long ago (perhaps your system clock is not up-to-date). Rejected message to avoid replay attacks."}
-            else
-              # mark message to prevent later replay of the message
-              mark_processed(sig_check.timestamp)
-              logger.info "Mail rejected as it is coming from the future (and may allow later replay)"
-              order = {:ok => false, :user => user, :msg => "The signature was made in the future (perhaps your system clock is not up-to-date). Rejected message to avoid replay attacks."}
-            end
-          end
+          # mark message to prevent later replay of the message
+          mark_processed(sig_check.timestamp)
+          order = Order.new(false, "The signature was made in the future (check your system clock)." +
+                            " Rejected message to avoid replay attacks.")
+          order.user = self.user
         end
-      else
-        logger.info "Mail content tampered or badly signed: " + sig_check.to_s
-        return nil
+        return order
       end
 
-      order.to_ostruct
+      signed_content = pgp_signed_part()
+
+      # create a fake mail and chain parsing operations
+      plain_mail = self.class.new(signed_content)
+      plain_mail.user = self.user
+      # propagate message_id to be able to mark messages (replay protection)
+      plein_mail.message_id = @mail.message_id
+      return plain_mail.parse
     end
 
     def parse_encrypted
-      order = {:ok => false, :msg => "mail not formatted correctly"}
-
       catch :notforme do
         begin
           # block is not passed to delegate (limitation ?)
@@ -228,6 +262,7 @@ module CyborgHood
 
           # create a fake mail and chain parsing operations
           clear_mail = self.class.new(clear_message)
+          clear_mail.user = self.user
           # propagate message_id to be able to mark messages (replay protection)
           clear_mail.message_id = @mail.message_id
           return clear_mail.parse
@@ -236,7 +271,7 @@ module CyborgHood
         end
       end
 
-      order.to_ostruct
+      Order.new(false, "Mail not formatted correctly (encrypted part).")
     end
 
     def mark_dir
diff --git a/postman b/postman
index d76ad46..a0ba4a7 100755
--- a/postman
+++ b/postman
@@ -277,15 +277,16 @@ module CyborgHood
           when :ignorable
           end
         end
-        if order.nil?
-          logger.info "Mail is invalid, ignoring..."
-          msg.delete
-          next
-        elsif not order.ok
-          logger.info "Sending reply for rejected message (#{order.msg})"
-          mail_reply = mail.create_simple_reject_reply("A message (ID: #{mail.message_id}) apparently from you was rejected for the following reason:\n  #{order.msg}")
-          mail_reply.crypt(order.user.keyFingerPrint) unless order.user.nil?
-          mail_reply.deliver
+        result_tag = order.ok ? "SUCCESS" : "FAILURE"
+        logger.info "Processing result: #{result_tag} (#{order.message})"
+        logger.info "Extra processing information: " + order.system_message if order.system_message
+        unless order.ok
+          if order.warn_sender
+            logger.info "Sending reply for rejected message"
+            mail_reply = mail.create_simple_reject_reply("A message (ID: #{mail.message_id}), apparently from you," +
+                                                         " was rejected for the following reason:\n  #{order.message}")
+            mail_reply.deliver
+          end
           msg.delete
           next
         end
@@ -295,7 +296,9 @@ module CyborgHood
 
         # create transcript
         logger.debug "Preparing reply"
-        reply_txt = "Hello #{order.user.cn},\n\nFollows the transcript of your commands:\n"
+        reply_txt = "Hello #{order.user.cn},\n\n"
+        reply_txt += order.message + "\n\n" if order.message
+        reply_txt += "Follows the transcript of your commands:\n"
         reply_attachments = []
         result_list.each do |result|
           reply_txt << "> #{result.cmd}\n"
