TODO

* milter-manager-children: multi mails in a session
  processing has some problems. We should check MILTER_STEP_NO_* cases.
* milter-manager: shutdown immediately when all child
  milters doesn't establish negotiation. (Now, returning
  negotiate reply.)
* milter-server: disable define macros on HEADER and
  BODY. Macro definitions on those states are invalid in
  libmilter. Wow!
* [1.7.x] support MAIL FROM parameters and RCPT TO parameters.
  * e.g.: MAIL FROM:<null@example.com> XVERP BODY=8BITMIME SIZE=5000
          -> "<null@example.com>\0XVERP\0BODY=8BITMIME\0SIZE=5000\0" packet.
  * e.g.: RCPT TO:<null@example.com> NOTIFY=SUCCESS ORCPT=rfc822;null@example.jp
          -> "<null@example.com>\0NOTIFY=SUCCESS\0ORCPT=rfc822;null@example.jp\0" packet.
* [1.5.0] Ruby bindings: write a document for creating milter
* [1.5.0] support Postfix access(5) and cidr_table(5) format
  for whitelist applicable condition.
--
* [1.5.x] make number of leaders to be checked per
  connection check customizable.
* [1.x.x] improve netstat performance.
  use net.inet.tcp.pcblist and net.inet6.ip6.stats
  on FreeBSD and /proc/net/tcp and /proc/net/tcp6 on Linux directly.
* [1.5.x] use UNIX domain socket rather than inet in document.
  Suggested by ZnZ.
* [1.5.x] multiply connection based anti-spam result as score.
  e.g. SFP fail -> 2.3, S25R match -> 7.8, ...;
       score = SPF fail * 0.3 + S25R match * 0.9 + ... = 0.69 + 7.02 + ...;
       threshold = 5;
       score < threshold -> pass, score > threshold -> tarpit, ...
* [1.5.x] show elapsed time in connection check log when disconnected.
* [1.5.x] output CVS for statistics.
* [1.5.x] add signals for logging. (each mail transaction
  finished for each milter and milter-manager, SMTP session
  finished for each milter and milter-manager)
  * MilterSessionResult
    * client name (milter manager or child milter name)
    * connect from
    * connected time
    * elapsed time
    * HELO domain
    * messages (list of MilterMessageResult)
  * MilterMessageResult
    * sender
    * recipients
    * headers
    * body size
    * state
    * status
    * added headers
    * quarntine
    * start time (time of received envelope-from)
    * elapsed time
  * session log signal passes MilterSessionResult
  * message log signal passes MilterSessionResult and MilterMessageResult
* Exim local_scan support.
* milter-test-server: stop processing if all recipients are rejected.
* XMail support.
* write a test for over max body chunk size (65535) and skip case.
  It's a case for dkim-filter.
* support Postfix SMTP Access Policy Delegation protocol.
* MilterCommandDecoder: support ESMTP parameters on MAIL FROM and RCPT TO.
* Move some signals (SIGINT, SIGHUP, SIGTERM) handling from milter-manager-main
  into milter_client_main since libmilter in sendmail handles those signals in
  smfi_main().
  And SIGPIPE should handle in libmilter-compatible.
-----
Index: milter/core/milter-command-decoder.c
===================================================================
--- milter/core/milter-command-decoder.c	(revision 2780)
+++ milter/core/milter-command-decoder.c	(working copy)
@@ -129,8 +129,8 @@
                      G_SIGNAL_RUN_LAST,
                      G_STRUCT_OFFSET(MilterCommandDecoderClass, envelope_from),
                      NULL, NULL,
-                     g_cclosure_marshal_VOID__STRING,
-                     G_TYPE_NONE, 1, G_TYPE_STRING);
+                     _milter_marshal_VOID__STRING_BOXED,
+                     G_TYPE_NONE, 2, G_TYPE_STRING, G_TYPE_HASH_TABLE);
 
     signals[ENVELOPE_RECIPIENT] =
         g_signal_new("envelope-recipient",
@@ -139,8 +139,8 @@
                      G_STRUCT_OFFSET(MilterCommandDecoderClass,
                                      envelope_recipient),
                      NULL, NULL,
-                     g_cclosure_marshal_VOID__STRING,
-                     G_TYPE_NONE, 1, G_TYPE_STRING);
+                     _milter_marshal_VOID__STRING_BOXED,
+                     G_TYPE_NONE, 2, G_TYPE_STRING, G_TYPE_HASH_TABLE);
 
     signals[DATA] =
         g_signal_new("data",
@@ -651,9 +651,14 @@
     if (null_character_point <= 0)
         return FALSE;
 
+    /* TODO: support parameters
+     * "<recipient-path>\0[PARAMETER1\0PARAMETER2\0...\0]"
+     * PARAMETER = "KEYWORD" or "KEYWORD=VALUE"
+     */
+
     milter_debug("[command-decoder][envelope-from] <%s>", buffer + 1);
 
-    g_signal_emit(decoder, signals[ENVELOPE_FROM], 0, buffer + 1);
+    g_signal_emit(decoder, signals[ENVELOPE_FROM], 0, buffer + 1, NULL);
 
     return TRUE;
 }
@@ -675,9 +680,14 @@
     if (null_character_point <= 0)
         return FALSE;
 
+    /* TODO: support parameters
+     * "<recipient-path>\0[PARAMETER1\0PARAMETER2\0...\0]"
+     * PARAMETER = "KEYWORD" or "KEYWORD=VALUE"
+     */
+
     milter_debug("[command-decoder][envelope-recipient] <%s>", buffer + 1);
 
-    g_signal_emit(decoder, signals[ENVELOPE_RECIPIENT], 0, buffer + 1);
+    g_signal_emit(decoder, signals[ENVELOPE_RECIPIENT], 0, buffer + 1, NULL);
     return TRUE;
 }
 
Index: milter/core/milter-command-decoder.h
===================================================================
--- milter/core/milter-command-decoder.h	(revision 2780)
+++ milter/core/milter-command-decoder.h	(working copy)
@@ -71,9 +71,11 @@
     void (*helo)                (MilterCommandDecoder *decoder,
                                  const gchar *fqdn);
     void (*envelope_from)       (MilterCommandDecoder *decoder,
-                                 const gchar *from);
+                                 const gchar *from,
+                                 GHashTable *parameters);
     void (*envelope_recipient)  (MilterCommandDecoder *decoder,
-                                 const gchar *recipient);
+                                 const gchar *recipient,
+                                 GHashTable *parameters);
     void (*data)                (MilterCommandDecoder *decoder);
     void (*header)              (MilterCommandDecoder *decoder,
                                  const gchar *name,
Index: milter/core/milter-marshalers.list
===================================================================
--- milter/core/milter-marshalers.list	(revision 2780)
+++ milter/core/milter-marshalers.list	(working copy)
@@ -10,6 +10,7 @@
 VOID:STRING,FLAGS,STRING,UINT,STRING,POINTER,STRING
 VOID:STRING,ENUM
 VOID:STRING,POINTER,UINT,ENUM
+VOID:STRING,BOXED
 VOID:POINTER,UINT
 VOID:UINT,STRING,STRING
 VOID:OBJECT,POINTER
Index: test/core/test-command-decoder.c
===================================================================
--- test/core/test-command-decoder.c	(revision 2780)
+++ test/core/test-command-decoder.c	(working copy)
@@ -1,6 +1,6 @@
 /* -*- Mode: C; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /*
- *  Copyright (C) 2008  Kouhei Sutou <kou@cozmixng.org>
+ *  Copyright (C) 2008-2009  Kouhei Sutou <kou@cozmixng.org>
  *
  *  This library is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU Lesser General Public License as published by
@@ -58,8 +58,10 @@
 void test_decode_helo_without_null (void);
 void test_decode_envelope_from (void);
 void test_decode_envelope_from_without_null (void);
+void test_decode_envelope_from_with_parameters (void);
 void test_decode_envelope_recipient (void);
 void test_decode_envelope_recipient_without_null (void);
+void test_decode_envelope_recipient_with_parameters (void);
 void test_decode_data (void);
 void test_decode_data_with_garbage (void);
 void test_decode_header (void);
@@ -111,8 +113,10 @@
 static gchar *helo_fqdn;
 
 static gchar *envelope_from;
+static GHashTable *envelope_from_parameters;
 
 static gchar *envelope_recipient;
+static GHashTable *envelope_recipient_parameters;
 
 static gchar *header_name;
 static gchar *header_value;
@@ -169,19 +173,27 @@
 }
 
 static void
-cb_envelope_from (MilterDecoder *decoder, const gchar *from, gpointer user_data)
+cb_envelope_from (MilterDecoder *decoder, const gchar *from,
+                  GHashTable *parameters, gpointer user_data)
 {
     n_envelope_froms++;
 
     envelope_from = g_strdup(from);
+    envelope_from_parameters = parameters;
+    if (envelope_from_parameters)
+        g_hash_table_ref(envelope_from_parameters);
 }
 
 static void
-cb_envelope_recipient (MilterDecoder *decoder, const gchar *to, gpointer user_data)
+cb_envelope_recipient (MilterDecoder *decoder, const gchar *to,
+                       GHashTable *parameters, gpointer user_data)
 {
     n_envelope_recipients++;
 
     envelope_recipient = g_strdup(to);
+    envelope_recipient_parameters = parameters;
+    if (envelope_recipient_parameters)
+        g_hash_table_ref(envelope_recipient_parameters);
 }
 
 static void
@@ -318,8 +330,10 @@
     helo_fqdn = NULL;
 
     envelope_from = NULL;
+    envelope_from_parameters = NULL;
 
     envelope_recipient = NULL;
+    envelope_recipient_parameters = NULL;
 
     header_name = NULL;
     header_value = NULL;
@@ -365,9 +379,13 @@
 
     if (envelope_from)
         g_free(envelope_from);
+    if (envelope_from_parameters)
+        g_hash_table_unref(envelope_from_parameters);
 
     if (envelope_recipient)
         g_free(envelope_recipient);
+    if (envelope_recipient_parameters)
+        g_hash_table_unref(envelope_recipient_parameters);
 
     if (header_name)
         g_free(header_name);
@@ -1257,6 +1275,8 @@
     gcut_assert_error(decode());
     cut_assert_equal_int(1, n_envelope_froms);
     cut_assert_equal_string(from, envelope_from);
+    gcut_assert_equal_hash_table_string_string(NULL,
+                                               envelope_from_parameters);
 }
 
 void
@@ -1276,6 +1296,31 @@
 }
 
 void
+test_decode_envelope_from_with_parameters (void)
+{
+    const gchar from[] = "<kou@cozmixng.org>";
+
+    g_string_append(buffer, "M");
+    g_string_append(buffer, from);
+    g_string_append_c(buffer, '\0');
+    g_string_append(buffer, "NAME1=VALUE1");
+    g_string_append_c(buffer, '\0');
+    g_string_append(buffer, "NAME2=VALUE2");
+    g_string_append_c(buffer, '\0');
+
+    gcut_assert_error(decode());
+    cut_assert_equal_int(1, n_envelope_froms);
+    cut_assert_equal_string(from, envelope_from);
+
+    cut_omit("TODO: support parameter parsing");
+    gcut_assert_equal_hash_table_string_string(
+        gcut_take_new_hash_table_string_string("NAME1", "VALUE1",
+                                               "NAME2", "VALUE2",
+                                               NULL),
+        envelope_from_parameters);
+}
+
+void
 test_decode_envelope_recipient (void)
 {
     const gchar recipient[] = "<kou@cozmixng.org>";
@@ -1287,6 +1332,8 @@
     gcut_assert_error(decode());
     cut_assert_equal_int(1, n_envelope_recipients);
     cut_assert_equal_string(recipient, envelope_recipient);
+    gcut_assert_equal_hash_table_string_string(NULL,
+                                               envelope_recipient_parameters);
 }
 
 void
@@ -1306,6 +1353,31 @@
 }
 
 void
+test_decode_envelope_recipient_with_parameters (void)
+{
+    const gchar recipient[] = "<kou@cozmixng.org>";
+
+    g_string_append(buffer, "R");
+    g_string_append(buffer, recipient);
+    g_string_append_c(buffer, '\0');
+    g_string_append(buffer, "NAME1=VALUE1");
+    g_string_append_c(buffer, '\0');
+    g_string_append(buffer, "NAME2=VALUE2");
+    g_string_append_c(buffer, '\0');
+
+    gcut_assert_error(decode());
+    cut_assert_equal_int(1, n_envelope_recipients);
+    cut_assert_equal_string(recipient, envelope_recipient);
+
+    cut_omit("TODO: support parameter parsing");
+    gcut_assert_equal_hash_table_string_string(
+        gcut_take_new_hash_table_string_string("NAME1", "VALUE1",
+                                               "NAME2", "VALUE2",
+                                               NULL),
+        envelope_recipient_parameters);
+}
+
+void
 test_decode_data (void)
 {
     g_string_append(buffer, "T");
-----
* MilterCommandEncoder support encoding ESMTP parameters on
  MAIL FROM and RCPT TO.
* envelope_from_stopper and envelope_recipient_stopper support ESMTP parameters.
-----
Index: doc/configuration.rd.ja
===================================================================
--- doc/configuration.rd.ja	(revision 2799)
+++ doc/configuration.rd.ja	(revision 2800)
@@ -742,7 +742,7 @@
        end
      end
 
-: define_envelope_from_stopper {|context, from| ...}
+: define_envelope_from_stopper {|context, from, parameters| ...}
 
    SMTPのMAIL FROMコマンドで渡された送信元アドレスを利用して
    子milterを適用するかどうかを判断します。このときに利用で
@@ -759,10 +759,16 @@
       MAIL FROMコマンドに渡された送信元です。
       例えば、"<sender@example.com>"となります。
 
+   : parameters
+      MAIL FROMコマンドに渡されたESMTPのパラメータです。
+      例えば、"RET=HDRS ENVID=QQ314159"というパラメータが渡
+      された場合は{"RET" => "HDRS", "ENVID" => "QQ314159"}と
+      なります。
+
    以下はexample.comから送信された場合はmilterを適用しない例
    です。
 
-     condition.define_envelope_from_stopper do |context, from|
+     condition.define_envelope_from_stopper do |context, from, parameters|
        if /@example.com>\z/ =~ from
          true
        else
@@ -770,7 +776,7 @@
        end
      end
 
-: define_envelope_recipient_stopper {|context, recipient| ...}
+: define_envelope_recipient_stopper {|context, recipient, parameters| ...}
 
    SMTPのRCPT TOコマンドで渡された宛先アドレスを利用して子
    milterを適用するかどうかを判断します。このときに利用でき
@@ -788,9 +794,16 @@
       RCPT TOコマンドに渡された宛先です。
       例えば、"<receiver@example.com>"となります。
 
+   : parameters
+      RCPT TOコマンドに渡されたESMTPのパラメータです。
+      例えば、"NOTIFY=SUCCESS ORCPT=rfc822;user@example.com"
+      というパラメータが渡された場合は
+      {"NOTIFY" => "SUCCESS", "ORCPT" => "rfc822;user@example.com"}
+      となります。
+
    以下はml.example.com宛の場合はmilterを適用しない例です。
 
-     condition.define_envelope_recipient_stopper do |context, recipient|
+     condition.define_envelope_recipient_stopper do |context, recipient, parameters|
        if /@ml.example.com>\z/ =~ recipient
          true
        else
Index: doc/configuration.rd
===================================================================
--- doc/configuration.rd	(revision 2799)
+++ doc/configuration.rd	(revision 2800)
@@ -748,7 +748,7 @@
        end
      end
 
-: define_envelope_from_stopper {|context, from| ...}
+: define_envelope_from_stopper {|context, from, parameters| ...}
 
    Decides whether the child milter is applied or not with
    envelope from address passed on MAIL FROM command of
@@ -765,10 +765,15 @@
       The envelope from address passed on MAIL FROM command.
       For example, "<sender@example.com>".
 
+   : parameters
+      The ESMTP parameters passed on MAIL FROM command.
+      For example, {"RET" => "HDRS", "ENVID" => "QQ314159"} for
+      "RET=HDRS ENVID=QQ314159" parameters.
+
    Here is an example that we stop the child milter when
    mails are sent from example.com.
 
-     condition.define_envelope_from_stopper do |context, from|
+     condition.define_envelope_from_stopper do |context, from, parameters|
        if /@example.com>\z/ =~ from
          true
        else
@@ -776,7 +781,7 @@
        end
      end
 
-: define_envelope_recipient_stopper {|context, recipient| ...}
+: define_envelope_recipient_stopper {|context, recipient, parameters| ...}
 
    Decides whether the child milter is applied or not with
    envelope recipient address passed on RCPT TO command of
@@ -794,6 +799,12 @@
       The envelope recipient address passed on RCPT TO command.
       For example, "<receiver@example.com>".
 
+   : parameters
+      The ESMTP parameters passed on RCPT TO command.
+      For example,
+      {"NOTIFY" => "SUCCESS", "ORCPT" => "rfc822;user@example.com"}
+      for "NOTIFY=SUCCESS ORCPT=rfc822;user@example.com" parameters.
+
    Here is an example that we stop the child milter when
    mails are sent to ml.example.com.
 
Index: data/applicable-conditions/authentication.conf
===================================================================
--- data/applicable-conditions/authentication.conf	(revision 2799)
+++ data/applicable-conditions/authentication.conf	(revision 2800)
@@ -3,7 +3,7 @@
 define_applicable_condition("Authenticated") do |condition|
   condition.description = "Apply a milter only when sender is authorized"
 
-  condition.define_envelope_from_stopper do |context, from|
+  condition.define_envelope_from_stopper do |context, from, parameters|
     not context.authenticated?
   end
 end
@@ -11,7 +11,7 @@
 define_applicable_condition("Unauthenticated") do |condition|
   condition.description = "Apply a milter only when sender is not authorized"
 
-  condition.define_envelope_from_stopper do |context, from|
+  condition.define_envelope_from_stopper do |context, from, parameters|
     context.authenticated?
   end
 end
Index: data/applicable-conditions/sendmail-compatible.conf
===================================================================
--- data/applicable-conditions/sendmail-compatible.conf	(revision 2799)
+++ data/applicable-conditions/sendmail-compatible.conf	(revision 2800)
@@ -12,7 +12,7 @@
     false
   end
 
-  condition.define_envelope_from_stopper do |context, from|
+  condition.define_envelope_from_stopper do |context, from, parameters|
     context["i"] ||= "dummy-id" if context.postfix?
     false
   end
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 2799)
+++ ChangeLog	(revision 2800)
@@ -1,5 +1,13 @@
 2009-03-08  Kouhei Sutou  <kou@cozmixng.org>
 
+	* doc/configuration.rd{,.ja}, binding/ruby/lib/milter/manager.rb:
+	pass ESMTP parameters to stoppers on MAIL FROM and RCPT TO but
+	not implemented yet. They are always {} for now.
+
+	* data/applicable-conditions/authentication.conf,
+	data/applicable-conditions/sendmail-compatible.conf: follow the
+	above change.
+
 	* TODO: add:
 	- MilterCommandDecoder: support ESMTP parameters on MAIL FROM and
 	  RCPT TO.
Index: binding/ruby/lib/milter/manager.rb
===================================================================
--- binding/ruby/lib/milter/manager.rb	(revision 2799)
+++ binding/ruby/lib/milter/manager.rb	(revision 2800)
@@ -741,7 +741,7 @@
               context = ChildContext.new(child, children)
               @envelope_from_stoppers.any? do |stopper|
                 ConfigurationLoader.guard(false) do
-                  stopper.call(context, from)
+                  stopper.call(context, from, {})
                 end
               end
             end
@@ -752,7 +752,7 @@
               context = ChildContext.new(child, children)
               @envelope_recipient_stoppers.any? do |stopper|
                 ConfigurationLoader.guard(false) do
-                  stopper.call(context, recipient)
+                  stopper.call(context, recipient, {})
                 end
               end
             end
-----
* if all alive child milters don't need to receive the
  command, children do nothing and leader returns response
  immediately not returning PROGRESS. For example:
Index: milter/manager/milter-manager-children.c
===================================================================
--- milter/manager/milter-manager-children.c	(revision 2280)
+++ milter/manager/milter-manager-children.c	(working copy)
@@ -2205,15 +2205,13 @@
     if (!milter_manager_children_check_alive(children))
         return FALSE;
 
+    priv = MILTER_MANAGER_CHILDREN_GET_PRIVATE(children);
+    priv->current_state = MILTER_SERVER_CONTEXT_STATE_DATA;
+
     if (!milter_manager_children_is_demanding_command(children,
-                                                      MILTER_COMMAND_DATA)) {
-        emit_no_demand_command_error(children, MILTER_COMMAND_DATA);
+                                                      MILTER_COMMAND_DATA))
         return FALSE;
-    }
 
-    priv = MILTER_MANAGER_CHILDREN_GET_PRIVATE(children);
-
-    priv->current_state = MILTER_SERVER_CONTEXT_STATE_DATA;
     init_command_waiting_child_queue(children, MILTER_COMMAND_DATA);
 
     return send_command_to_first_waiting_child(children, MILTER_COMMAND_DATA);
Index: milter/manager/milter-manager-leader.c
===================================================================
--- milter/manager/milter-manager-leader.c	(revision 2280)
+++ milter/manager/milter-manager-leader.c	(working copy)
@@ -783,10 +783,12 @@
     if (!priv->children)
         return MILTER_STATUS_NOT_CHANGE;
 
-    if (milter_manager_children_data(priv->children))
+    if (milter_manager_children_data(priv->children)) {
         return MILTER_STATUS_PROGRESS;
-    else
-        return MILTER_STATUS_NOT_CHANGE; /* FIXME: reject or accept */
+    } else {
+        priv->state = next_state(leader, priv->state);
+        return MILTER_STATUS_NOT_CHANGE;
+    }
 }
 
 MilterStatus
* bug? milter-manager sometimes doesn't finish child milter?
* change process name of forked process launcher.
* send quit command to launcher on manager dispose.
* use chroot
* add --disable-milter-manager configure option.
* add --disable-ruby configure option.
* tool/milter-test-server:
  * support --macro=CONTEXT:NAME:VALUE
  * support extracting multiple {reverse,forward}-paths from
    envelope-from and envelope-recipient address in --mail-file.
* tool/milter-test-client:
  * support outputting reply information.
  * support customizing reply by command line option.
* add default applicable conditions:
  ideas:
    * S25R
    * DNSBL: http://spam-champuru.livedoor.com/dnsbl/
    * remote network (local network may not be a spammer)
      * getifaddrs(3) can be used to determine local network.
    * detected as spam (X-Spam-Flag:, X-Bogosity:)
    * detected as virus (X-Virus-Status:)
    * mailing list? (X-ML-Name)
* graphs:
  * child milters alive and dead.
    (This can not be drawn by rrdtool since rrdtool db does not handle variable items)
  * ...

* performance:
  * at least:
    * 50_000 mails/day (0.58 mails/sec)
      * 500 users
      * a user receives 100 mails/day
    * CPU: ???
    * Memory: ???
    * child milters:
      * milter-greylist
      * clamav-milter
      * spamass-milter
      * sid-milter
      * dkim-milter
      * dnsbl-milter

  * FYI:
    * BBSec Sentrion MP 4/8(2008/11)
      http://www.bbsec.co.jp/products/Sentrion_MP_48.html
      * 1_500_000 mails/day (17.36 mails/sec)
      * CPU: Quad Core Intel Xeon E5472,12M Cache,3.0GHz x 2 1600MHz FSB
      * Memory: 8GB

    * Sohpos Email Appliance (2008/11)
      http://sophos.com/sophos/docs/eng/factshts/sophos-email-appliances-dsus.pdf
      http://www.sophos.co.jp/sophos/docs/jpn/factshts/sophos-email-appliances-dsjp.pdf
     * ES1000:
       * 20_000 mails/hour (5.56 mails/sec)
       * CPU: Intel Celeron D 2.93GHz
       * Memory: 1GB
     * ES4000:
       * 80_000 mails/hour (22.22 mails/sec)
       * CPU: Intel Xeon 64-bit 3.2 GHz x 2
       * Memory: 2GB
    * HDE Anti-Spam for Gateway (2008/12)
      http://www.hde.co.jp/has/require/
      * 5_000 mails/hour (1.39 mails/sec)
      * CPU: Intel Pentium Xeon 2GHz
      * Memory: 2GB
* fix FIXME in data/applicable-conditions/remote-network.conf
  * add local network option?
* milter-manager can be ran as normal user if milter-manager process is
  invoked as root user. just only control connection handler and child
  milter process invoker can be ran as root user.
* milter_manager_egg_to_xml_string(): add user name, timeouts and
  command options (<- needed?)
* milter-manager supports macros requests.
* milter-client-context should also close writer on timeout.
* support MAIL FROM/RCPT TO additional info parsing.
  (MilterClientContext::envelope-from, MilterClientContext::envelope-recipient)
  cited from SMTP (RFC 2821) 4.1.1.2 MAIL (MAIL):
       "MAIL FROM:" ("<>" / Reverse-Path)
                    [SP Mail-parameters] CRLF

  cited from SMTP (RFC 2821) 4.1.1.3 RECIPIENT (RCPT):
       "RCPT TO:" ("<Postmaster@" domain ">" / "<Postmaster>" / Forward-Path)
			[SP Rcpt-parameters] CRLF

  cited from SMTP (RFC 2821) 4.1.2 Command Argument Syntax:
       Reverse-path = Path
       Forward-path = Path
       Path = "<" [ A-d-l ":" ] Mailbox ">"
       A-d-l = At-domain *( "," A-d-l )
             ; Note that this form, the so-called "source route",
             ; MUST BE accepted, SHOULD NOT be generated, and SHOULD be
             ; ignored.
       At-domain = "@" domain
       Mail-parameters = esmtp-param *(SP esmtp-param)
       Rcpt-parameters = esmtp-param *(SP esmtp-param)
       esmtp-param     = esmtp-keyword ["=" esmtp-value]
       esmtp-keyword   = (ALPHA / DIGIT) *(ALPHA / DIGIT / "-")
       esmtp-value     = 1*(%d33-60 / %d62-127)
	     ; any CHAR excluding "=", SP, and control characters
       Keyword  = Ldh-str
       Argument = Atom
       Domain = (sub-domain 1*("." sub-domain)) / address-literal
       sub-domain = Let-dig [Ldh-str]
       address-literal = "[" IPv4-address-literal /
			     IPv6-address-literal /
			     General-address-literal "]"
	     ; See section 4.1.3
       Mailbox = Local-part "@" Domain
       Local-part = Dot-string / Quoted-string
	     ; MAY be case-sensitive
       Dot-string = Atom *("." Atom)
       Atom = 1*atext
       Quoted-string = DQUOTE *qcontent DQUOTE
       String = Atom / Quoted-string

  cited from SMTP (RFC 2821) 4.1.3 Address Literals:
       IPv4-address-literal = Snum 3("." Snum)
       IPv6-address-literal = "IPv6:" IPv6-addr
       General-address-literal = Standardized-tag ":" 1*dcontent
       Standardized-tag = Ldh-str
             ; MUST be specified in a standards-track RFC
             ; and registered with IANA
       Snum = 1*3DIGIT  ; representing a decimal integer
             ; value in the range 0 through 255
       Let-dig = ALPHA / DIGIT
       Ldh-str = *( ALPHA / DIGIT / "-" ) Let-dig
       IPv6-addr = IPv6-full / IPv6-comp / IPv6v4-full / IPv6v4-comp
       IPv6-hex  = 1*4HEXDIG
       IPv6-full = IPv6-hex 7(":" IPv6-hex)
       IPv6-comp = [IPv6-hex *5(":" IPv6-hex)] "::" [IPv6-hex *5(":"
		  IPv6-hex)]
	     ; The "::" represents at least 2 16-bit groups of zeros
	     ; No more than 6 groups in addition to the "::" may be
	     ; present
       IPv6v4-full = IPv6-hex 5(":" IPv6-hex) ":" IPv4-address-literal
       IPv6v4-comp = [IPv6-hex *3(":" IPv6-hex)] "::"
		    [IPv6-hex *3(":" IPv6-hex) ":"] IPv4-address-literal
	     ; The "::" represents at least 2 16-bit groups of zeros
	     ; No more than 4 groups in addition to the "::" and
	     ; IPv4-address-literal may be present

   cited from Internet Message Format (RFC 2822) 3.2.3. Folding white space and comments:
	FWS             =       ([*WSP CRLF] 1*WSP) /   ; Folding white space
				obs-FWS
	ctext           =       NO-WS-CTL /     ; Non white space controls
				%d33-39 /       ; The rest of the US-ASCII
				%d42-91 /       ;  characters not including "(",
				%d93-126        ;  ")", or "\"
	ccontent        =       ctext / quoted-pair / comment
	comment         =       "(" *([FWS] ccontent) [FWS] ")"
	CFWS            =       *([FWS] comment) (([FWS] comment) / FWS)

   cited from Internet Message Format (RFC 2822) 3.2.4. Atom:
	atext           =       ALPHA / DIGIT / ; Any character except controls,
				"!" / "#" /     ;  SP, and specials.
				"$" / "%" /     ;  Used for atoms
				"&" / "'" /
				"*" / "+" /
				"-" / "/" /
				"=" / "?" /
				"^" / "_" /
				"`" / "{" /
				"|" / "}" /
				"~"
	atom            =       [CFWS] 1*atext [CFWS]
	dot-atom        =       [CFWS] dot-atom-text [CFWS]
	dot-atom-text   =       1*atext *("." 1*atext)

   cited from Internet Message Format (RFC 2822) 3.2.1. Primitive Tokens:
        text            =       %d1-9 /         ; Characters excluding CR and LF
                                %d11 /
                                %d12 /
                                %d14-127 /
                                obs-text

   cited from Internet Message Format (RFC 2822) 3.2.2. Quoted characters:
        quoted-pair     =       ("\" text) / obs-qp

   cited from Internet Message Format (RFC 2822) 3.2.5. Quoted strings:
	qtext           =       NO-WS-CTL /     ; Non white space controls
				%d33 /          ; The rest of the US-ASCII
				%d35-91 /       ;  characters not including "\"
				%d93-126        ;  or the quote character
	qcontent        =       qtext / quoted-pair
	quoted-string   =       [CFWS]
				DQUOTE *([FWS] qcontent) [FWS] DQUOTE
				[CFWS]

   cited from Internet Message Format (RFC 2822) 4.1. Miscellaneous obsolete tokens:
	obs-qp          =       "\" (%d0-127)
	obs-text        =       *LF *CR *(obs-char *LF *CR)

	obs-char        =       %d0-9 / %d11 /          ; %d0-127 except CR and
				%d12 / %d14-127         ;  LF


* milter-client-context supports MilterStepFlags.
* check client context's modify operations (e.g. milter_client_add_header())
  are called on end-of-message state.