smtp_setup_msg(void)
{
int done = 0;
BOOL toomany = FALSE;
BOOL discarded = FALSE;
BOOL last_was_rej_mail = FALSE;
BOOL last_was_rcpt = FALSE;
void *reset_point = store_get(0);

DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");

/* Reset for start of new message. We allow one RSET not to be counted as a
nonmail command, for those MTAs that insist on sending it between every
message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
TLS between messages (an Exim client may do this if it has messages queued up
for the host). Note: we do NOT reset AUTH at this point. */

smtp_reset(reset_point);
message_ended = END_NOTSTARTED;

chunking_state = f.chunking_offered ? CHUNKING_OFFERED : CHUNKING_NOT_OFFERED;

cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
#ifdef SUPPORT_TLS
cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
#endif

/* Set the local signal handler for SIGTERM - it tries to end off tidily */

had_command_sigterm = 0;
os_non_restarting_signal(SIGTERM, command_sigterm_handler);

/* Batched SMTP is handled in a different function. */

if (smtp_batched_input) return smtp_setup_batch_msg();

/* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
value. The values are 2 larger than the required yield of the function. */

while (done <= 0)
  {
  const uschar **argv;
  uschar *etrn_command;
  uschar *etrn_serialize_key;
  uschar *errmess;
  uschar *log_msg, *smtp_code;
  uschar *user_msg = NULL;
  uschar *recipient = NULL;
  uschar *hello = NULL;
  uschar *s, *ss;
  BOOL was_rej_mail = FALSE;
  BOOL was_rcpt = FALSE;
  void (*oldsignal)(int);
  pid_t pid;
  int start, end, sender_domain, recipient_domain;
  int rc;
  int c;
  auth_instance *au;
  uschar *orcpt = NULL;
  int dsn_flags;
  gstring * g;

#ifdef AUTH_TLS
  /* Check once per STARTTLS or SSL-on-connect for a TLS AUTH */
  if (  tls_in.active.sock >= 0
     && tls_in.peercert
     && tls_in.certificate_verified
     && cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd
     )
    {
    cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = FALSE;

    for (au = auths; au; au = au->next)
      if (strcmpic(US"tls", au->driver_name) == 0)
	{
	if (  acl_smtp_auth
	   && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
		      &user_msg, &log_msg)) != OK
	   )
	  done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
	else
	  {
	  smtp_cmd_data = NULL;

	  if (smtp_in_auth(au, &s, &ss) == OK)
	    { DEBUG(D_auth) debug_printf("tls auth succeeded\n"); }
	  else
	    { DEBUG(D_auth) debug_printf("tls auth not succeeded\n"); }
	  }
	break;
	}
    }
#endif

#ifdef TCP_QUICKACK
  if (smtp_in)		/* Avoid pure-ACKs while in cmd pingpong phase */
    (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
	    US &off, sizeof(off));
#endif

  switch(smtp_read_command(
#ifdef EXPERIMENTAL_PIPE_CONNECT
	  !fl.pipe_connect_acceptable,
#else
	  TRUE,
#endif
	  GETC_BUFFER_UNLIMITED))
    {
    /* The AUTH command is not permitted to occur inside a transaction, and may
    occur successfully only once per connection. Actually, that isn't quite
    true. When TLS is started, all previous information about a connection must
    be discarded, so a new AUTH is permitted at that time.

    AUTH may only be used when it has been advertised. However, it seems that
    there are clients that send AUTH when it hasn't been advertised, some of
    them even doing this after HELO. And there are MTAs that accept this. Sigh.
    So there's a get-out that allows this to happen.

    AUTH is initially labelled as a "nonmail command" so that one occurrence
    doesn't get counted. We change the label here so that multiple failing
    AUTHS will eventually hit the nonmail threshold. */

    case AUTH_CMD:
      HAD(SCH_AUTH);
      authentication_failed = TRUE;
      cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;

      if (!fl.auth_advertised && !f.allow_auth_unadvertised)
	{
	done = synprot_error(L_smtp_protocol_error, 503, NULL,
	  US"AUTH command used when not advertised");
	break;
	}
      if (sender_host_authenticated)
	{
	done = synprot_error(L_smtp_protocol_error, 503, NULL,
	  US"already authenticated");
	break;
	}
      if (sender_address)
	{
	done = synprot_error(L_smtp_protocol_error, 503, NULL,
	  US"not permitted in mail transaction");
	break;
	}

      /* Check the ACL */

      if (  acl_smtp_auth
	 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
		    &user_msg, &log_msg)) != OK
	 )
	{
	done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
	break;
	}

      /* Find the name of the requested authentication mechanism. */

      s = smtp_cmd_data;
      while ((c = *smtp_cmd_data) != 0 && !isspace(c))
	{
	if (!isalnum(c) && c != '-' && c != '_')
	  {
	  done = synprot_error(L_smtp_syntax_error, 501, NULL,
	    US"invalid character in authentication mechanism name");
	  goto COMMAND_LOOP;
	  }
	smtp_cmd_data++;
	}

      /* If not at the end of the line, we must be at white space. Terminate the
      name and move the pointer on to any data that may be present. */

      if (*smtp_cmd_data != 0)
	{
	*smtp_cmd_data++ = 0;
	while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
	}

      /* Search for an authentication mechanism which is configured for use
      as a server and which has been advertised (unless, sigh, allow_auth_
      unadvertised is set). */

      for (au = auths; au; au = au->next)
	if (strcmpic(s, au->public_name) == 0 && au->server &&
	    (au->advertised || f.allow_auth_unadvertised))
	  break;

      if (au)
	{
	c = smtp_in_auth(au, &s, &ss);

	smtp_printf("%s\r\n", FALSE, s);
	if (c != OK)
	  log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
	    au->name, host_and_ident(FALSE), ss);
	}
      else
	done = synprot_error(L_smtp_protocol_error, 504, NULL,
	  string_sprintf("%s authentication mechanism not supported", s));

      break;  /* AUTH_CMD */

    /* The HELO/EHLO commands are permitted to appear in the middle of a
    session as well as at the beginning. They have the effect of a reset in
    addition to their other functions. Their absence at the start cannot be
    taken to be an error.

    RFC 2821 says:

      If the EHLO command is not acceptable to the SMTP server, 501, 500,
      or 502 failure replies MUST be returned as appropriate.  The SMTP
      server MUST stay in the same state after transmitting these replies
      that it was in before the EHLO was received.

    Therefore, we do not do the reset until after checking the command for
    acceptability. This change was made for Exim release 4.11. Previously
    it did the reset first. */

    case HELO_CMD:
      HAD(SCH_HELO);
      hello = US"HELO";
      fl.esmtp = FALSE;
      goto HELO_EHLO;

    case EHLO_CMD:
      HAD(SCH_EHLO);
      hello = US"EHLO";
      fl.esmtp = TRUE;

    HELO_EHLO:      /* Common code for HELO and EHLO */
      cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
      cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;

      /* Reject the HELO if its argument was invalid or non-existent. A
      successful check causes the argument to be saved in malloc store. */

      if (!check_helo(smtp_cmd_data))
	{
	smtp_printf("501 Syntactically invalid %s argument(s)\r\n", FALSE, hello);

	log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
	  "invalid argument(s): %s", hello, host_and_ident(FALSE),
	  *smtp_cmd_argument == 0 ? US"(no argument given)" :
			     string_printing(smtp_cmd_argument));

	if (++synprot_error_count > smtp_max_synprot_errors)
	  {
	  log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
	    "syntax or protocol errors (last command was \"%s\")",
	    host_and_ident(FALSE), string_printing(smtp_cmd_buffer));
	  done = 1;
	  }

	break;
	}

      /* If sender_host_unknown is true, we have got here via the -bs interface,
      not called from inetd. Otherwise, we are running an IP connection and the
      host address will be set. If the helo name is the primary name of this
      host and we haven't done a reverse lookup, force one now. If helo_required
      is set, ensure that the HELO name matches the actual host. If helo_verify
      is set, do the same check, but softly. */

      if (!f.sender_host_unknown)
	{
	BOOL old_helo_verified = f.helo_verified;
	uschar *p = smtp_cmd_data;

	while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
	*p = 0;

	/* Force a reverse lookup if HELO quoted something in helo_lookup_domains
	because otherwise the log can be confusing. */

	if (  !sender_host_name
	   && (deliver_domain = sender_helo_name,  /* set $domain */
	       match_isinlist(sender_helo_name, CUSS &helo_lookup_domains, 0,
		&domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL)) == OK)
	  (void)host_name_lookup();

	/* Rebuild the fullhost info to include the HELO name (and the real name
	if it was looked up.) */

	host_build_sender_fullhost();  /* Rebuild */
	set_process_info("handling%s incoming connection from %s",
	  tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));

	/* Verify if configured. This doesn't give much security, but it does
	make some people happy to be able to do it. If helo_required is set,
	(host matches helo_verify_hosts) failure forces rejection. If helo_verify
	is set (host matches helo_try_verify_hosts), it does not. This is perhaps
	now obsolescent, since the verification can now be requested selectively
	at ACL time. */

	f.helo_verified = f.helo_verify_failed = sender_helo_dnssec = FALSE;
	if (fl.helo_required || fl.helo_verify)
	  {
	  BOOL tempfail = !smtp_verify_helo();
	  if (!f.helo_verified)
	    {
	    if (fl.helo_required)
	      {
	      smtp_printf("%d %s argument does not match calling host\r\n", FALSE,
		tempfail? 451 : 550, hello);
	      log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
		tempfail? "temporarily " : "",
		hello, sender_helo_name, host_and_ident(FALSE));
	      f.helo_verified = old_helo_verified;
	      break;                   /* End of HELO/EHLO processing */
	      }
	    HDEBUG(D_all) debug_printf("%s verification failed but host is in "
	      "helo_try_verify_hosts\n", hello);
	    }
	  }
	}

#ifdef SUPPORT_SPF
      /* set up SPF context */
      spf_init(sender_helo_name, sender_host_address);
#endif

      /* Apply an ACL check if one is defined; afterwards, recheck
      synchronization in case the client started sending in a delay. */

      if (acl_smtp_helo)
	if ((rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo,
		  &user_msg, &log_msg)) != OK)
	  {
	  done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
	  if (sender_helo_name)
	    {
	    store_free(sender_helo_name);
	    sender_helo_name = NULL;
	    }
	  host_build_sender_fullhost();  /* Rebuild */
	  break;
	  }
#ifdef EXPERIMENTAL_PIPE_CONNECT
	else if (!fl.pipe_connect_acceptable && !check_sync())
#else
	else if (!check_sync())
#endif
	  goto SYNC_FAILURE;

      /* Generate an OK reply. The default string includes the ident if present,
      and also the IP address if present. Reflecting back the ident is intended
      as a deterrent to mail forgers. For maximum efficiency, and also because
      some broken systems expect each response to be in a single packet, arrange
      that the entire reply is sent in one write(). */

      fl.auth_advertised = FALSE;
      f.smtp_in_pipelining_advertised = FALSE;
#ifdef SUPPORT_TLS
      fl.tls_advertised = FALSE;
# ifdef EXPERIMENTAL_REQUIRETLS
      fl.requiretls_advertised = FALSE;
# endif
#endif
      fl.dsn_advertised = FALSE;
#ifdef SUPPORT_I18N
      fl.smtputf8_advertised = FALSE;
#endif

      smtp_code = US"250 ";        /* Default response code plus space*/
      if (!user_msg)
	{
	s = string_sprintf("%.3s %s Hello %s%s%s",
	  smtp_code,
	  smtp_active_hostname,
	  sender_ident ? sender_ident : US"",
	  sender_ident ? US" at " : US"",
	  sender_host_name ? sender_host_name : sender_helo_name);
	g = string_cat(NULL, s);

	if (sender_host_address)
	  {
	  g = string_catn(g, US" [", 2);
	  g = string_cat (g, sender_host_address);
	  g = string_catn(g, US"]", 1);
	  }
	}

      /* A user-supplied EHLO greeting may not contain more than one line. Note
      that the code returned by smtp_message_code() includes the terminating
      whitespace character. */

      else
	{
	char *ss;
	int codelen = 4;
	smtp_message_code(&smtp_code, &codelen, &user_msg, NULL, TRUE);
	s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
	if ((ss = strpbrk(CS s, "\r\n")) != NULL)
	  {
	  log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
	    "newlines: message truncated: %s", string_printing(s));
	  *ss = 0;
	  }
	g = string_cat(NULL, s);
	}

      g = string_catn(g, US"\r\n", 2);

      /* If we received EHLO, we must create a multiline response which includes
      the functions supported. */

      if (fl.esmtp)
	{
	g->s[3] = '-';

	/* I'm not entirely happy with this, as an MTA is supposed to check
	that it has enough room to accept a message of maximum size before
	it sends this. However, there seems little point in not sending it.
	The actual size check happens later at MAIL FROM time. By postponing it
	till then, VRFY and EXPN can be used after EHLO when space is short. */

	if (thismessage_size_limit > 0)
	  {
	  sprintf(CS big_buffer, "%.3s-SIZE %d\r\n", smtp_code,
	    thismessage_size_limit);
	  g = string_cat(g, big_buffer);
	  }
	else
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-SIZE\r\n", 7);
	  }

	/* Exim does not do protocol conversion or data conversion. It is 8-bit
	clean; if it has an 8-bit character in its hand, it just sends it. It
	cannot therefore specify 8BITMIME and remain consistent with the RFCs.
	However, some users want this option simply in order to stop MUAs
	mangling messages that contain top-bit-set characters. It is therefore
	provided as an option. */

	if (accept_8bitmime)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-8BITMIME\r\n", 11);
	  }

	/* Advertise DSN support if configured to do so. */
	if (verify_check_host(&dsn_advertise_hosts) != FAIL)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-DSN\r\n", 6);
	  fl.dsn_advertised = TRUE;
	  }

	/* Advertise ETRN/VRFY/EXPN if there's are ACL checking whether a host is
	permitted to issue them; a check is made when any host actually tries. */

	if (acl_smtp_etrn)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-ETRN\r\n", 7);
	  }
	if (acl_smtp_vrfy)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-VRFY\r\n", 7);
	  }
	if (acl_smtp_expn)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-EXPN\r\n", 7);
	  }

	/* Exim is quite happy with pipelining, so let the other end know that
	it is safe to use it, unless advertising is disabled. */

	if (  f.pipelining_enable
	   && verify_check_host(&pipelining_advertise_hosts) == OK)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-PIPELINING\r\n", 13);
	  sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
	  f.smtp_in_pipelining_advertised = TRUE;

#ifdef EXPERIMENTAL_PIPE_CONNECT
	  if (fl.pipe_connect_acceptable)
	    {
	    f.smtp_in_early_pipe_advertised = TRUE;
	    g = string_catn(g, smtp_code, 3);
	    g = string_catn(g, US"-" EARLY_PIPE_FEATURE_NAME "\r\n", EARLY_PIPE_FEATURE_LEN+3);
	    }
#endif
	  }


	/* If any server authentication mechanisms are configured, advertise
	them if the current host is in auth_advertise_hosts. The problem with
	advertising always is that some clients then require users to
	authenticate (and aren't configurable otherwise) even though it may not
	be necessary (e.g. if the host is in host_accept_relay).

	RFC 2222 states that SASL mechanism names contain only upper case
	letters, so output the names in upper case, though we actually recognize
	them in either case in the AUTH command. */

	if (  auths
#ifdef AUTH_TLS
	   && !sender_host_authenticated
#endif
	   && verify_check_host(&auth_advertise_hosts) == OK
	   )
	  {
	  auth_instance *au;
	  BOOL first = TRUE;
	  for (au = auths; au; au = au->next)
	    {
	    au->advertised = FALSE;
	    if (au->server)
	      {
	      DEBUG(D_auth+D_expand) debug_printf_indent(
		"Evaluating advertise_condition for %s athenticator\n",
		au->public_name);
	      if (  !au->advertise_condition
		 || expand_check_condition(au->advertise_condition, au->name,
			US"authenticator")
		 )
		{
		int saveptr;
		if (first)
		  {
		  g = string_catn(g, smtp_code, 3);
		  g = string_catn(g, US"-AUTH", 5);
		  first = FALSE;
		  fl.auth_advertised = TRUE;
		  }
		saveptr = g->ptr;
		g = string_catn(g, US" ", 1);
		g = string_cat (g, au->public_name);
		while (++saveptr < g->ptr) g->s[saveptr] = toupper(g->s[saveptr]);
		au->advertised = TRUE;
		}
	      }
	    }

	  if (!first) g = string_catn(g, US"\r\n", 2);
	  }

	/* RFC 3030 CHUNKING */

	if (verify_check_host(&chunking_advertise_hosts) != FAIL)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-CHUNKING\r\n", 11);
	  f.chunking_offered = TRUE;
	  chunking_state = CHUNKING_OFFERED;
	  }

	/* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
	if it has been included in the binary, and the host matches
	tls_advertise_hosts. We must *not* advertise if we are already in a
	secure connection. */

#ifdef SUPPORT_TLS
	if (tls_in.active.sock < 0 &&
	    verify_check_host(&tls_advertise_hosts) != FAIL)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-STARTTLS\r\n", 11);
	  fl.tls_advertised = TRUE;
	  }

# ifdef EXPERIMENTAL_REQUIRETLS
	/* Advertise REQUIRETLS only once we are in a secure connection */
	if (  tls_in.active.sock >= 0
	   && verify_check_host(&tls_advertise_requiretls) != FAIL)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-REQUIRETLS\r\n", 13);
	  fl.requiretls_advertised = TRUE;
	  }
# endif
#endif

#ifndef DISABLE_PRDR
	/* Per Recipient Data Response, draft by Eric A. Hall extending RFC */
	if (prdr_enable)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-PRDR\r\n", 7);
	  }
#endif

#ifdef SUPPORT_I18N
	if (  accept_8bitmime
	   && verify_check_host(&smtputf8_advertise_hosts) != FAIL)
	  {
	  g = string_catn(g, smtp_code, 3);
	  g = string_catn(g, US"-SMTPUTF8\r\n", 11);
	  fl.smtputf8_advertised = TRUE;
	  }
#endif

	/* Finish off the multiline reply with one that is always available. */

	g = string_catn(g, smtp_code, 3);
	g = string_catn(g, US" HELP\r\n", 7);
	}

      /* Terminate the string (for debug), write it, and note that HELO/EHLO
      has been seen. */

#ifdef SUPPORT_TLS
      if (tls_in.active.sock >= 0)
	(void)tls_write(NULL, g->s, g->ptr,
# ifdef EXPERIMENTAL_PIPE_CONNECT
			fl.pipe_connect_acceptable && pipeline_connect_sends());
# else
			FALSE);
# endif
      else
#endif

	{
	int i = fwrite(g->s, 1, g->ptr, smtp_out); i = i; /* compiler quietening */
	}
      DEBUG(D_receive)
	{
	uschar *cr;

	(void) string_from_gstring(g);
	while ((cr = Ustrchr(g->s, '\r')) != NULL)   /* lose CRs */
	  memmove(cr, cr + 1, (g->ptr--) - (cr - g->s));
	debug_printf("SMTP>> %s", g->s);
	}
      fl.helo_seen = TRUE;

      /* Reset the protocol and the state, abandoning any previous message. */
      received_protocol =
	(sender_host_address ? protocols : protocols_local)
	  [ (fl.esmtp
	    ? pextend + (sender_host_authenticated ? pauthed : 0)
	    : pnormal)
	  + (tls_in.active.sock >= 0 ? pcrpted : 0)
	  ];
      cancel_cutthrough_connection(TRUE, US"sent EHLO response");
      smtp_reset(reset_point);
      toomany = FALSE;
      break;   /* HELO/EHLO */


    /* The MAIL command requires an address as an operand. All we do
    here is to parse it for syntactic correctness. The form "<>" is
    a special case which converts into an empty string. The start/end
    pointers in the original are not used further for this address, as
    it is the canonical extracted address which is all that is kept. */

    case MAIL_CMD:
      HAD(SCH_MAIL);
      smtp_mailcmd_count++;              /* Count for limit and ratelimit */
      was_rej_mail = TRUE;               /* Reset if accepted */
      env_mail_type_t * mail_args;       /* Sanity check & validate args */

      if (fl.helo_required && !fl.helo_seen)
	{
	smtp_printf("503 HELO or EHLO required\r\n", FALSE);
	log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
	  "HELO/EHLO given", host_and_ident(FALSE));
	break;
	}

      if (sender_address)
	{
	done = synprot_error(L_smtp_protocol_error, 503, NULL,
	  US"sender already given");
	break;
	}

      if (!*smtp_cmd_data)
	{
	done = synprot_error(L_smtp_protocol_error, 501, NULL,
	  US"MAIL must have an address operand");
	break;
	}

      /* Check to see if the limit for messages per connection would be
      exceeded by accepting further messages. */

      if (smtp_accept_max_per_connection > 0 &&
	  smtp_mailcmd_count > smtp_accept_max_per_connection)
	{
	smtp_printf("421 too many messages in this connection\r\n", FALSE);
	log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
	  "messages in one connection", host_and_ident(TRUE));
	break;
	}

      /* Reset for start of message - even if this is going to fail, we
      obviously need to throw away any previous data. */

      cancel_cutthrough_connection(TRUE, US"MAIL received");
      smtp_reset(reset_point);
      toomany = FALSE;
      sender_data = recipient_data = NULL;

      /* Loop, checking for ESMTP additions to the MAIL FROM command. */

      if (fl.esmtp) for(;;)
	{
	uschar *name, *value, *end;
	unsigned long int size;
	BOOL arg_error = FALSE;

	if (!extract_option(&name, &value)) break;

	for (mail_args = env_mail_type_list;
	     mail_args->value != ENV_MAIL_OPT_NULL;
	     mail_args++
	    )
	  if (strcmpic(name, mail_args->name) == 0)
	    break;
	if (mail_args->need_value && strcmpic(value, US"") == 0)
	  break;

	switch(mail_args->value)
	  {
	  /* Handle SIZE= by reading the value. We don't do the check till later,
	  in order to be able to log the sender address on failure. */
	  case ENV_MAIL_OPT_SIZE:
	    if (((size = Ustrtoul(value, &end, 10)), *end == 0))
	      {
	      if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
		size = INT_MAX;
	      message_size = (int)size;
	      }
	    else
	      arg_error = TRUE;
	    break;

	  /* If this session was initiated with EHLO and accept_8bitmime is set,
	  Exim will have indicated that it supports the BODY=8BITMIME option. In
	  fact, it does not support this according to the RFCs, in that it does not
	  take any special action for forwarding messages containing 8-bit
	  characters. That is why accept_8bitmime is not the default setting, but
	  some sites want the action that is provided. We recognize both "8BITMIME"
	  and "7BIT" as body types, but take no action. */
	  case ENV_MAIL_OPT_BODY:
	    if (accept_8bitmime) {
	      if (strcmpic(value, US"8BITMIME") == 0)
		body_8bitmime = 8;
	      else if (strcmpic(value, US"7BIT") == 0)
		body_8bitmime = 7;
	      else
		{
		body_8bitmime = 0;
		done = synprot_error(L_smtp_syntax_error, 501, NULL,
		  US"invalid data for BODY");
		goto COMMAND_LOOP;
		}
	      DEBUG(D_receive) debug_printf("8BITMIME: %d\n", body_8bitmime);
	      break;
	    }
	    arg_error = TRUE;
	    break;

	  /* Handle the two DSN options, but only if configured to do so (which
	  will have caused "DSN" to be given in the EHLO response). The code itself
	  is included only if configured in at build time. */

	  case ENV_MAIL_OPT_RET:
	    if (fl.dsn_advertised)
	      {
	      /* Check if RET has already been set */
	      if (dsn_ret > 0)
		{
		done = synprot_error(L_smtp_syntax_error, 501, NULL,
		  US"RET can be specified once only");
		goto COMMAND_LOOP;
		}
	      dsn_ret = strcmpic(value, US"HDRS") == 0
		? dsn_ret_hdrs
		: strcmpic(value, US"FULL") == 0
		? dsn_ret_full
		: 0;
	      DEBUG(D_receive) debug_printf("DSN_RET: %d\n", dsn_ret);
	      /* Check for invalid invalid value, and exit with error */
	      if (dsn_ret == 0)
		{
		done = synprot_error(L_smtp_syntax_error, 501, NULL,
		  US"Value for RET is invalid");
		goto COMMAND_LOOP;
		}
	      }
	    break;
	  case ENV_MAIL_OPT_ENVID:
	    if (fl.dsn_advertised)
	      {
	      /* Check if the dsn envid has been already set */
	      if (dsn_envid)
		{
		done = synprot_error(L_smtp_syntax_error, 501, NULL,
		  US"ENVID can be specified once only");
		goto COMMAND_LOOP;
		}
	      dsn_envid = string_copy(value);
	      DEBUG(D_receive) debug_printf("DSN_ENVID: %s\n", dsn_envid);
	      }
	    break;

	  /* Handle the AUTH extension. If the value given is not "<>" and either
	  the ACL says "yes" or there is no ACL but the sending host is
	  authenticated, we set it up as the authenticated sender. However, if the
	  authenticator set a condition to be tested, we ignore AUTH on MAIL unless
	  the condition is met. The value of AUTH is an xtext, which means that +,
	  = and cntrl chars are coded in hex; however "<>" is unaffected by this
	  coding. */
	  case ENV_MAIL_OPT_AUTH:
	    if (Ustrcmp(value, "<>") != 0)
	      {
	      int rc;
	      uschar *ignore_msg;

	      if (auth_xtextdecode(value, &authenticated_sender) < 0)
		{
		/* Put back terminator overrides for error message */
		value[-1] = '=';
		name[-1] = ' ';
		done = synprot_error(L_smtp_syntax_error, 501, NULL,
		  US"invalid data for AUTH");
		goto COMMAND_LOOP;
		}
	      if (!acl_smtp_mailauth)
		{
		ignore_msg = US"client not authenticated";
		rc = sender_host_authenticated ? OK : FAIL;
		}
	      else
		{
		ignore_msg = US"rejected by ACL";
		rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
		  &user_msg, &log_msg);
		}

	      switch (rc)
		{
		case OK:
		  if (authenticated_by == NULL ||
		      authenticated_by->mail_auth_condition == NULL ||
		      expand_check_condition(authenticated_by->mail_auth_condition,
			  authenticated_by->name, US"authenticator"))
		    break;     /* Accept the AUTH */

		  ignore_msg = US"server_mail_auth_condition failed";
		  if (authenticated_id != NULL)
		    ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
		      ignore_msg, authenticated_id);

		/* Fall through */

		case FAIL:
		  authenticated_sender = NULL;
		  log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
		    value, host_and_ident(TRUE), ignore_msg);
		  break;

		/* Should only get DEFER or ERROR here. Put back terminator
		overrides for error message */

		default:
		  value[-1] = '=';
		  name[-1] = ' ';
		  (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
		    log_msg);
		  goto COMMAND_LOOP;
		}
	      }
	      break;

#ifndef DISABLE_PRDR
	  case ENV_MAIL_OPT_PRDR:
	    if (prdr_enable)
	      prdr_requested = TRUE;
	    break;
#endif

#ifdef SUPPORT_I18N
	  case ENV_MAIL_OPT_UTF8:
	    if (!fl.smtputf8_advertised)
	      {
	      done = synprot_error(L_smtp_syntax_error, 501, NULL,
		US"SMTPUTF8 used when not advertised");
	      goto COMMAND_LOOP;
	      }

	    DEBUG(D_receive) debug_printf("smtputf8 requested\n");
	    message_smtputf8 = allow_utf8_domains = TRUE;
	    if (Ustrncmp(received_protocol, US"utf8", 4) != 0)
	      {
	      int old_pool = store_pool;
	      store_pool = POOL_PERM;
	      received_protocol = string_sprintf("utf8%s", received_protocol);
	      store_pool = old_pool;
	      }
	    break;
#endif

#if defined(SUPPORT_TLS) && defined(EXPERIMENTAL_REQUIRETLS)
	  case ENV_MAIL_OPT_REQTLS:
	    {
	    uschar * r, * t;

	    if (!fl.requiretls_advertised)
	      {
	      done = synprot_error(L_smtp_syntax_error, 555, NULL,
		US"unadvertised MAIL option: REQUIRETLS");
	      goto COMMAND_LOOP;
	      }

	    DEBUG(D_receive) debug_printf("requiretls requested\n");
	    tls_requiretls = REQUIRETLS_MSG;

	    r = string_copy_malloc(received_protocol);
	    if ((t = Ustrrchr(r, 's'))) *t = 'S';
	    received_protocol = r;
	    }
	    break;
#endif

	  /* No valid option. Stick back the terminator characters and break
	  the loop.  Do the name-terminator second as extract_option sets
	  value==name when it found no equal-sign.
	  An error for a malformed address will occur. */
	  case ENV_MAIL_OPT_NULL:
	    value[-1] = '=';
	    name[-1] = ' ';
	    arg_error = TRUE;
	    break;

	  default:  assert(0);
	  }
	/* Break out of for loop if switch() had bad argument or
	   when start of the email address is reached */
	if (arg_error) break;
	}

#if defined(SUPPORT_TLS) && defined(EXPERIMENTAL_REQUIRETLS)
      if (tls_requiretls & REQUIRETLS_MSG)
	{
	/* Ensure headers-only bounces whether a RET option was given or not. */

	DEBUG(D_receive) if (dsn_ret == dsn_ret_full)
	  debug_printf("requiretls override: dsn_ret_full -> dsn_ret_hdrs\n");
	dsn_ret = dsn_ret_hdrs;
	}
#endif

      /* If we have passed the threshold for rate limiting, apply the current
      delay, and update it for next time, provided this is a limited host. */

      if (smtp_mailcmd_count > smtp_rlm_threshold &&
	  verify_check_host(&smtp_ratelimit_hosts) == OK)
	{
	DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
	  smtp_delay_mail/1000.0);
	millisleep((int)smtp_delay_mail);
	smtp_delay_mail *= smtp_rlm_factor;
	if (smtp_delay_mail > (double)smtp_rlm_limit)
	  smtp_delay_mail = (double)smtp_rlm_limit;
	}

      /* Now extract the address, first applying any SMTP-time rewriting. The
      TRUE flag allows "<>" as a sender address. */

      raw_sender = rewrite_existflags & rewrite_smtp
	? rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
		      global_rewrite_rules)
	: smtp_cmd_data;

      raw_sender =
	parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
	  TRUE);

      if (!raw_sender)
	{
	done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
	break;
	}

      sender_address = raw_sender;

      /* If there is a configured size limit for mail, check that this message
      doesn't exceed it. The check is postponed to this point so that the sender
      can be logged. */

      if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
	{
	smtp_printf("552 Message size exceeds maximum permitted\r\n", FALSE);
	log_write(L_size_reject,
	    LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
	    "message too big: size%s=%d max=%d",
	    sender_address,
	    host_and_ident(TRUE),
	    (message_size == INT_MAX)? ">" : "",
	    message_size,
	    thismessage_size_limit);
	sender_address = NULL;
	break;
	}

      /* Check there is enough space on the disk unless configured not to.
      When smtp_check_spool_space is set, the check is for thismessage_size_limit
      plus the current message - i.e. we accept the message only if it won't
      reduce the space below the threshold. Add 5000 to the size to allow for
      overheads such as the Received: line and storing of recipients, etc.
      By putting the check here, even when SIZE is not given, it allow VRFY
      and EXPN etc. to be used when space is short. */

      if (!receive_check_fs(
	   (smtp_check_spool_space && message_size >= 0)?
	      message_size + 5000 : 0))
	{
	smtp_printf("452 Space shortage, please try later\r\n", FALSE);
	sender_address = NULL;
	break;
	}

      /* If sender_address is unqualified, reject it, unless this is a locally
      generated message, or the sending host or net is permitted to send
      unqualified addresses - typically local machines behaving as MUAs -
      in which case just qualify the address. The flag is set above at the start
      of the SMTP connection. */

      if (!sender_domain && *sender_address)
	if (f.allow_unqualified_sender)
	  {
	  sender_domain = Ustrlen(sender_address) + 1;
	  sender_address = rewrite_address_qualify(sender_address, FALSE);
	  DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
	    raw_sender);
	  }
	else
	  {
	  smtp_printf("501 %s: sender address must contain a domain\r\n", FALSE,
	    smtp_cmd_data);
	  log_write(L_smtp_syntax_error,
	    LOG_MAIN|LOG_REJECT,
	    "unqualified sender rejected: <%s> %s%s",
	    raw_sender,
	    host_and_ident(TRUE),
	    host_lookup_msg);
	  sender_address = NULL;
	  break;
	  }

      /* Apply an ACL check if one is defined, before responding. Afterwards,
      when pipelining is not advertised, do another sync check in case the ACL
      delayed and the client started sending in the meantime. */

      if (acl_smtp_mail)
	{
	rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
	if (rc == OK && !f.smtp_in_pipelining_advertised && !check_sync())
	  goto SYNC_FAILURE;
	}
      else
	rc = OK;

      if (rc == OK || rc == DISCARD)
	{
	BOOL more = pipeline_response();

	if (!user_msg)
	  smtp_printf("%s%s%s", more, US"250 OK",
		    #ifndef DISABLE_PRDR
		      prdr_requested ? US", PRDR Requested" : US"",
		    #else
		      US"",
		    #endif
		      US"\r\n");
	else
	  {
	#ifndef DISABLE_PRDR
	  if (prdr_requested)
	     user_msg = string_sprintf("%s%s", user_msg, US", PRDR Requested");
	#endif
	  smtp_user_msg(US"250", user_msg);
	  }
	smtp_delay_rcpt = smtp_rlr_base;
	f.recipients_discarded = (rc == DISCARD);
	was_rej_mail = FALSE;
	}
      else
	{
	done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
	sender_address = NULL;
	}
      break;


    /* The RCPT command requires an address as an operand. There may be any
    number of RCPT commands, specifying multiple recipients. We build them all
    into a data structure. The start/end values given by parse_extract_address
    are not used, as we keep only the extracted address. */

    case RCPT_CMD:
      HAD(SCH_RCPT);
      rcpt_count++;
      was_rcpt = fl.rcpt_in_progress = TRUE;

      /* There must be a sender address; if the sender was rejected and
      pipelining was advertised, we assume the client was pipelining, and do not
      count this as a protocol error. Reset was_rej_mail so that further RCPTs
      get the same treatment. */

      if (sender_address == NULL)
	{
	if (f.smtp_in_pipelining_advertised && last_was_rej_mail)
	  {
	  smtp_printf("503 sender not yet given\r\n", FALSE);
	  was_rej_mail = TRUE;
	  }
	else
	  {
	  done = synprot_error(L_smtp_protocol_error, 503, NULL,
	    US"sender not yet given");
	  was_rcpt = FALSE;             /* Not a valid RCPT */
	  }
	rcpt_fail_count++;
	break;
	}

      /* Check for an operand */

      if (smtp_cmd_data[0] == 0)
	{
	done = synprot_error(L_smtp_syntax_error, 501, NULL,
	  US"RCPT must have an address operand");
	rcpt_fail_count++;
	break;
	}

      /* Set the DSN flags orcpt and dsn_flags from the session*/
      orcpt = NULL;
      dsn_flags = 0;

      if (fl.esmtp) for(;;)
	{
	uschar *name, *value;

	if (!extract_option(&name, &value))
	  break;

	if (fl.dsn_advertised && strcmpic(name, US"ORCPT") == 0)
	  {
	  /* Check whether orcpt has been already set */
	  if (orcpt)
	    {
	    done = synprot_error(L_smtp_syntax_error, 501, NULL,
	      US"ORCPT can be specified once only");
	    goto COMMAND_LOOP;
	    }
	  orcpt = string_copy(value);
	  DEBUG(D_receive) debug_printf("DSN orcpt: %s\n", orcpt);
	  }

	else if (fl.dsn_advertised && strcmpic(name, US"NOTIFY") == 0)
	  {
	  /* Check if the notify flags have been already set */
	  if (dsn_flags > 0)
	    {
	    done = synprot_error(L_smtp_syntax_error, 501, NULL,
		US"NOTIFY can be specified once only");
	    goto COMMAND_LOOP;
	    }
	  if (strcmpic(value, US"NEVER") == 0)
	    dsn_flags |= rf_notify_never;
	  else
	    {
	    uschar *p = value;
	    while (*p != 0)
	      {
	      uschar *pp = p;
	      while (*pp != 0 && *pp != ',') pp++;
	      if (*pp == ',') *pp++ = 0;
	      if (strcmpic(p, US"SUCCESS") == 0)
		{
		DEBUG(D_receive) debug_printf("DSN: Setting notify success\n");
		dsn_flags |= rf_notify_success;
		}
	      else if (strcmpic(p, US"FAILURE") == 0)
		{
		DEBUG(D_receive) debug_printf("DSN: Setting notify failure\n");
		dsn_flags |= rf_notify_failure;
		}
	      else if (strcmpic(p, US"DELAY") == 0)
		{
		DEBUG(D_receive) debug_printf("DSN: Setting notify delay\n");
		dsn_flags |= rf_notify_delay;
		}
	      else
		{
		/* Catch any strange values */
		done = synprot_error(L_smtp_syntax_error, 501, NULL,
		  US"Invalid value for NOTIFY parameter");
		goto COMMAND_LOOP;
		}
	      p = pp;
	      }
	      DEBUG(D_receive) debug_printf("DSN Flags: %x\n", dsn_flags);
	    }
	  }

	/* Unknown option. Stick back the terminator characters and break
	the loop. An error for a malformed address will occur. */

	else
	  {
	  DEBUG(D_receive) debug_printf("Invalid RCPT option: %s : %s\n", name, value);
	  name[-1] = ' ';
	  value[-1] = '=';
	  break;
	  }
	}

      /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
      as a recipient address */

      recipient = rewrite_existflags & rewrite_smtp
	? rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
	    global_rewrite_rules)
	: smtp_cmd_data;

      if (!(recipient = parse_extract_address(recipient, &errmess, &start, &end,
	&recipient_domain, FALSE)))
	{
	done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
	rcpt_fail_count++;
	break;
	}

      /* If the recipient address is unqualified, reject it, unless this is a
      locally generated message. However, unqualified addresses are permitted
      from a configured list of hosts and nets - typically when behaving as
      MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
      really. The flag is set at the start of the SMTP connection.

      RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
      assumed this meant "reserved local part", but the revision of RFC 821 and
      friends now makes it absolutely clear that it means *mailbox*. Consequently
      we must always qualify this address, regardless. */

      if (!recipient_domain)
	if (!(recipient_domain = qualify_recipient(&recipient, smtp_cmd_data,
				    US"recipient")))
	  {
	  rcpt_fail_count++;
	  break;
	  }

      /* Check maximum allowed */

      if (rcpt_count > recipients_max && recipients_max > 0)
	{
	if (recipients_max_reject)
	  {
	  rcpt_fail_count++;
	  smtp_printf("552 too many recipients\r\n", FALSE);
	  if (!toomany)
	    log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
	      "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
	  }
	else
	  {
	  rcpt_defer_count++;
	  smtp_printf("452 too many recipients\r\n", FALSE);
	  if (!toomany)
	    log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
	      "temporarily rejected: sender=<%s> %s", sender_address,
	      host_and_ident(TRUE));
	  }

	toomany = TRUE;
	break;
	}

      /* If we have passed the threshold for rate limiting, apply the current
      delay, and update it for next time, provided this is a limited host. */

      if (rcpt_count > smtp_rlr_threshold &&
	  verify_check_host(&smtp_ratelimit_hosts) == OK)
	{
	DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
	  smtp_delay_rcpt/1000.0);
	millisleep((int)smtp_delay_rcpt);
	smtp_delay_rcpt *= smtp_rlr_factor;
	if (smtp_delay_rcpt > (double)smtp_rlr_limit)
	  smtp_delay_rcpt = (double)smtp_rlr_limit;
	}

      /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
      for them. Otherwise, check the access control list for this recipient. As
      there may be a delay in this, re-check for a synchronization error
      afterwards, unless pipelining was advertised. */

      if (f.recipients_discarded)
	rc = DISCARD;
      else
	if (  (rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
		      &log_msg)) == OK
	   && !f.smtp_in_pipelining_advertised && !check_sync())
	  goto SYNC_FAILURE;

      /* The ACL was happy */

      if (rc == OK)
	{
	BOOL more = pipeline_response();

	if (user_msg)
	  smtp_user_msg(US"250", user_msg);
	else
	  smtp_printf("250 Accepted\r\n", more);
	receive_add_recipient(recipient, -1);

	/* Set the dsn flags in the recipients_list */
	recipients_list[recipients_count-1].orcpt = orcpt;
	recipients_list[recipients_count-1].dsn_flags = dsn_flags;

	DEBUG(D_receive) debug_printf("DSN: orcpt: %s  flags: %d\n",
	  recipients_list[recipients_count-1].orcpt,
	  recipients_list[recipients_count-1].dsn_flags);
	}

      /* The recipient was discarded */

      else if (rc == DISCARD)
	{
	if (user_msg)
	  smtp_user_msg(US"250", user_msg);
	else
	  smtp_printf("250 Accepted\r\n", FALSE);
	rcpt_fail_count++;
	discarded = TRUE;
	log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> RCPT %s: "
	  "discarded by %s ACL%s%s", host_and_ident(TRUE),
	  sender_address_unrewritten? sender_address_unrewritten : sender_address,
	  smtp_cmd_argument, f.recipients_discarded? "MAIL" : "RCPT",
	  log_msg ? US": " : US"", log_msg ? log_msg : US"");
	}

      /* Either the ACL failed the address, or it was deferred. */

      else
	{
	if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
	done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
	}
      break;


    /* The DATA command is legal only if it follows successful MAIL FROM
    and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
    not counted as a protocol error if it follows RCPT (which must have been
    rejected if there are no recipients.) This function is complete when a
    valid DATA command is encountered.

    Note concerning the code used: RFC 2821 says this:

     -  If there was no MAIL, or no RCPT, command, or all such commands
        were rejected, the server MAY return a "command out of sequence"
        (503) or "no valid recipients" (554) reply in response to the
        DATA command.

    The example in the pipelining RFC 2920 uses 554, but I use 503 here
    because it is the same whether pipelining is in use or not.

    If all the RCPT commands that precede DATA provoked the same error message
    (often indicating some kind of system error), it is helpful to include it
    with the DATA rejection (an idea suggested by Tony Finch). */

    case BDAT_CMD:
      {
      int n;

      HAD(SCH_BDAT);
      if (chunking_state != CHUNKING_OFFERED)
	{
	done = synprot_error(L_smtp_protocol_error, 503, NULL,
	  US"BDAT command used when CHUNKING not advertised");
	break;
	}

      /* grab size, endmarker */

      if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
	{
	done = synprot_error(L_smtp_protocol_error, 501, NULL,
	  US"missing size for BDAT command");
	break;
	}
      chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
	? CHUNKING_LAST : CHUNKING_ACTIVE;
      chunking_data_left = chunking_datasize;
      DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
				    (int)chunking_state, chunking_data_left);

      /* push the current receive_* function on the "stack", and
      replace them by bdat_getc(), which in turn will use the lwr_receive_*
      functions to do the dirty work. */
      lwr_receive_getc = receive_getc;
      lwr_receive_getbuf = receive_getbuf;
      lwr_receive_ungetc = receive_ungetc;

      receive_getc = bdat_getc;
      receive_ungetc = bdat_ungetc;

      f.dot_ends = FALSE;

      goto DATA_BDAT;
      }

    case DATA_CMD:
      HAD(SCH_DATA);
      f.dot_ends = TRUE;

    DATA_BDAT:		/* Common code for DATA and BDAT */
#ifdef EXPERIMENTAL_PIPE_CONNECT
      fl.pipe_connect_acceptable = FALSE;
#endif
      if (!discarded && recipients_count <= 0)
	{
	if (fl.rcpt_smtp_response_same && rcpt_smtp_response != NULL)
	  {
	  uschar *code = US"503";
	  int len = Ustrlen(rcpt_smtp_response);
	  smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
	    "this error:");
	  /* Responses from smtp_printf() will have \r\n on the end */
	  if (len > 2 && rcpt_smtp_response[len-2] == '\r')
	    rcpt_smtp_response[len-2] = 0;
	  smtp_respond(code, 3, FALSE, rcpt_smtp_response);
	  }
	if (f.smtp_in_pipelining_advertised && last_was_rcpt)
	  smtp_printf("503 Valid RCPT command must precede %s\r\n", FALSE,
	    smtp_names[smtp_connection_had[smtp_ch_index-1]]);
	else
	  done = synprot_error(L_smtp_protocol_error, 503, NULL,
	    smtp_connection_had[smtp_ch_index-1] == SCH_DATA
	    ? US"valid RCPT command must precede DATA"
	    : US"valid RCPT command must precede BDAT");

	if (chunking_state > CHUNKING_OFFERED)
	  bdat_flush_data();
	break;
	}

      if (toomany && recipients_max_reject)
	{
	sender_address = NULL;  /* This will allow a new MAIL without RSET */
	sender_address_unrewritten = NULL;
	smtp_printf("554 Too many recipients\r\n", FALSE);
	break;
	}

      if (chunking_state > CHUNKING_OFFERED)
	rc = OK;			/* No predata ACL or go-ahead output for BDAT */
      else
	{
	/* If there is an ACL, re-check the synchronization afterwards, since the
	ACL may have delayed.  To handle cutthrough delivery enforce a dummy call
	to get the DATA command sent. */

	if (acl_smtp_predata == NULL && cutthrough.cctx.sock < 0)
	  rc = OK;
	else
	  {
	  uschar * acl = acl_smtp_predata ? acl_smtp_predata : US"accept";
	  f.enable_dollar_recipients = TRUE;
	  rc = acl_check(ACL_WHERE_PREDATA, NULL, acl, &user_msg,
	    &log_msg);
	  f.enable_dollar_recipients = FALSE;
	  if (rc == OK && !check_sync())
	    goto SYNC_FAILURE;

	  if (rc != OK)
	    {	/* Either the ACL failed the address, or it was deferred. */
	    done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
	    break;
	    }
	  }

	if (user_msg)
	  smtp_user_msg(US"354", user_msg);
	else
	  smtp_printf(
	    "354 Enter message, ending with \".\" on a line by itself\r\n", FALSE);
	}

#ifdef TCP_QUICKACK
      if (smtp_in)	/* all ACKs needed to ramp window up for bulk data */
	(void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
		US &on, sizeof(on));
#endif
      done = 3;
      message_ended = END_NOTENDED;   /* Indicate in middle of data */

      break;


    case VRFY_CMD:
      {
      uschar * address;

      HAD(SCH_VRFY);

      if (!(address = parse_extract_address(smtp_cmd_data, &errmess,
            &start, &end, &recipient_domain, FALSE)))
	{
	smtp_printf("501 %s\r\n", FALSE, errmess);
	break;
	}

      if (!recipient_domain)
	if (!(recipient_domain = qualify_recipient(&address, smtp_cmd_data,
				    US"verify")))
	  break;

      if ((rc = acl_check(ACL_WHERE_VRFY, address, acl_smtp_vrfy,
		    &user_msg, &log_msg)) != OK)
	done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
      else
	{
	uschar * s = NULL;
	address_item * addr = deliver_make_addr(address, FALSE);

	switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
	       -1, -1, NULL, NULL, NULL))
	  {
	  case OK:
	    s = string_sprintf("250 <%s> is deliverable", address);
	    break;

	  case DEFER:
	    s = (addr->user_message != NULL)?
	      string_sprintf("451 <%s> %s", address, addr->user_message) :
	      string_sprintf("451 Cannot resolve <%s> at this time", address);
	    break;

	  case FAIL:
	    s = (addr->user_message != NULL)?
	      string_sprintf("550 <%s> %s", address, addr->user_message) :
	      string_sprintf("550 <%s> is not deliverable", address);
	    log_write(0, LOG_MAIN, "VRFY failed for %s %s",
	      smtp_cmd_argument, host_and_ident(TRUE));
	    break;
	  }

	smtp_printf("%s\r\n", FALSE, s);
	}
      break;
      }


    case EXPN_CMD:
      HAD(SCH_EXPN);
      rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
      if (rc != OK)
	done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
      else
	{
	BOOL save_log_testing_mode = f.log_testing_mode;
	f.address_test_mode = f.log_testing_mode = TRUE;
	(void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
	  smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
	  NULL, NULL, NULL);
	f.address_test_mode = FALSE;
	f.log_testing_mode = save_log_testing_mode;    /* true for -bh */
	}
      break;


    #ifdef SUPPORT_TLS

    case STARTTLS_CMD:
      HAD(SCH_STARTTLS);
      if (!fl.tls_advertised)
	{
	done = synprot_error(L_smtp_protocol_error, 503, NULL,
	  US"STARTTLS command used when not advertised");
	break;
	}

      /* Apply an ACL check if one is defined */

      if (  acl_smtp_starttls
	 && (rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls,
		    &user_msg, &log_msg)) != OK
	 )
	{
	done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
	break;
	}

      /* RFC 2487 is not clear on when this command may be sent, though it
      does state that all information previously obtained from the client
      must be discarded if a TLS session is started. It seems reasonable to
      do an implied RSET when STARTTLS is received. */

      incomplete_transaction_log(US"STARTTLS");
      cancel_cutthrough_connection(TRUE, US"STARTTLS received");
      smtp_reset(reset_point);
      toomany = FALSE;
      cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;

      /* There's an attack where more data is read in past the STARTTLS command
      before TLS is negotiated, then assumed to be part of the secure session
      when used afterwards; we use segregated input buffers, so are not
      vulnerable, but we want to note when it happens and, for sheer paranoia,
      ensure that the buffer is "wiped".
      Pipelining sync checks will normally have protected us too, unless disabled
      by configuration. */

      if (receive_smtp_buffered())
	{
	DEBUG(D_any)
	  debug_printf("Non-empty input buffer after STARTTLS; naive attack?\n");
	if (tls_in.active.sock < 0)
	  smtp_inend = smtp_inptr = smtp_inbuffer;
	/* and if TLS is already active, tls_server_start() should fail */
	}

      /* There is nothing we value in the input buffer and if TLS is successfully
      negotiated, we won't use this buffer again; if TLS fails, we'll just read
      fresh content into it.  The buffer contains arbitrary content from an
      untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
      It seems safest to just wipe away the content rather than leave it as a
      target to jump to. */

      memset(smtp_inbuffer, 0, IN_BUFFER_SIZE);

      /* Attempt to start up a TLS session, and if successful, discard all
      knowledge that was obtained previously. At least, that's what the RFC says,
      and that's what happens by default. However, in order to work round YAEB,
      there is an option to remember the esmtp state. Sigh.

      We must allow for an extra EHLO command and an extra AUTH command after
      STARTTLS that don't add to the nonmail command count. */

      s = NULL;
      if ((rc = tls_server_start(tls_require_ciphers, &s)) == OK)
	{
	if (!tls_remember_esmtp)
	  fl.helo_seen = fl.esmtp = fl.auth_advertised = f.smtp_in_pipelining_advertised = FALSE;
	cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
	cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
	cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
	if (sender_helo_name)
	  {
	  store_free(sender_helo_name);
	  sender_helo_name = NULL;
	  host_build_sender_fullhost();  /* Rebuild */
	  set_process_info("handling incoming TLS connection from %s",
	    host_and_ident(FALSE));
	  }
	received_protocol =
	  (sender_host_address ? protocols : protocols_local)
	    [ (fl.esmtp
	      ? pextend + (sender_host_authenticated ? pauthed : 0)
	      : pnormal)
	    + (tls_in.active.sock >= 0 ? pcrpted : 0)
	    ];

	sender_host_auth_pubname = sender_host_authenticated = NULL;
	authenticated_id = NULL;
	sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
	DEBUG(D_tls) debug_printf("TLS active\n");
	break;     /* Successful STARTTLS */
	}
      else
	(void) smtp_log_tls_fail(s);

      /* Some local configuration problem was discovered before actually trying
      to do a TLS handshake; give a temporary error. */

      if (rc == DEFER)
	{
	smtp_printf("454 TLS currently unavailable\r\n", FALSE);
	break;
	}

      /* Hard failure. Reject everything except QUIT or closed connection. One
      cause for failure is a nested STARTTLS, in which case tls_in.active remains
      set, but we must still reject all incoming commands.  Another is a handshake
      failure - and there may some encrypted data still in the pipe to us, which we
      see as garbage commands. */

      DEBUG(D_tls) debug_printf("TLS failed to start\n");
      while (done <= 0) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
	{
	case EOF_CMD:
	  log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
	    smtp_get_connection_info());
	  smtp_notquit_exit(US"tls-failed", NULL, NULL);
	  done = 2;
	  break;

	/* It is perhaps arguable as to which exit ACL should be called here,
	but as it is probably a situation that almost never arises, it
	probably doesn't matter. We choose to call the real QUIT ACL, which in
	some sense is perhaps "right". */

	case QUIT_CMD:
	  user_msg = NULL;
	  if (  acl_smtp_quit
	     && ((rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
				&log_msg)) == ERROR))
	      log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
		log_msg);
	  if (user_msg)
	    smtp_respond(US"221", 3, TRUE, user_msg);
	  else
	    smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
	  log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
	    smtp_get_connection_info());
	  done = 2;
	  break;

	default:
	  smtp_printf("554 Security failure\r\n", FALSE);
	  break;
	}
      tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
      break;
    #endif


    /* The ACL for QUIT is provided for gathering statistical information or
    similar; it does not affect the response code, but it can supply a custom
    message. */

    case QUIT_CMD:
      smtp_quit_handler(&user_msg, &log_msg);
      done = 2;
      break;


    case RSET_CMD:
      smtp_rset_handler();
      cancel_cutthrough_connection(TRUE, US"RSET received");
      smtp_reset(reset_point);
      toomany = FALSE;
      break;


    case NOOP_CMD:
      HAD(SCH_NOOP);
      smtp_printf("250 OK\r\n", FALSE);
      break;


    /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
    used, a check will be done for permitted hosts. Show STARTTLS only if not
    already in a TLS session and if it would be advertised in the EHLO
    response. */

    case HELP_CMD:
      HAD(SCH_HELP);
      smtp_printf("214-Commands supported:\r\n", TRUE);
	{
	uschar buffer[256];
	buffer[0] = 0;
	Ustrcat(buffer, " AUTH");
	#ifdef SUPPORT_TLS
	if (tls_in.active.sock < 0 &&
	    verify_check_host(&tls_advertise_hosts) != FAIL)
	  Ustrcat(buffer, " STARTTLS");
	#endif
	Ustrcat(buffer, " HELO EHLO MAIL RCPT DATA BDAT");
	Ustrcat(buffer, " NOOP QUIT RSET HELP");
	if (acl_smtp_etrn != NULL) Ustrcat(buffer, " ETRN");
	if (acl_smtp_expn != NULL) Ustrcat(buffer, " EXPN");
	if (acl_smtp_vrfy != NULL) Ustrcat(buffer, " VRFY");
	smtp_printf("214%s\r\n", FALSE, buffer);
	}
      break;


    case EOF_CMD:
      incomplete_transaction_log(US"connection lost");
      smtp_notquit_exit(US"connection-lost", US"421",
	US"%s lost input connection", smtp_active_hostname);

      /* Don't log by default unless in the middle of a message, as some mailers
      just drop the call rather than sending QUIT, and it clutters up the logs.
      */

      if (sender_address || recipients_count > 0)
	log_write(L_lost_incoming_connection, LOG_MAIN,
	  "unexpected %s while reading SMTP command from %s%s%s D=%s",
	  f.sender_host_unknown ? "EOF" : "disconnection",
	  f.tcp_in_fastopen_logged
	  ? US""
	  : f.tcp_in_fastopen
	  ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO "
	  : US"",
	  host_and_ident(FALSE), smtp_read_error,
	  string_timesince(&smtp_connection_start)
	  );

      else
	log_write(L_smtp_connection, LOG_MAIN, "%s %slost%s D=%s",
	  smtp_get_connection_info(),
	  f.tcp_in_fastopen && !f.tcp_in_fastopen_logged ? US"TFO " : US"",
	  smtp_read_error,
	  string_timesince(&smtp_connection_start)
	  );

      done = 1;
      break;


    case ETRN_CMD:
      HAD(SCH_ETRN);
      if (sender_address)
	{
	done = synprot_error(L_smtp_protocol_error, 503, NULL,
	  US"ETRN is not permitted inside a transaction");
	break;
	}

      log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
	host_and_ident(FALSE));

      if ((rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn,
		  &user_msg, &log_msg)) != OK)
	{
	done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
	break;
	}

      /* Compute the serialization key for this command. */

      etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);

      /* If a command has been specified for running as a result of ETRN, we
      permit any argument to ETRN. If not, only the # standard form is permitted,
      since that is strictly the only kind of ETRN that can be implemented
      according to the RFC. */

      if (smtp_etrn_command)
	{
	uschar *error;
	BOOL rc;
	etrn_command = smtp_etrn_command;
	deliver_domain = smtp_cmd_data;
	rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
	  US"ETRN processing", &error);
	deliver_domain = NULL;
	if (!rc)
	  {
	  log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
	    error);
	  smtp_printf("458 Internal failure\r\n", FALSE);
	  break;
	  }
	}

      /* Else set up to call Exim with the -R option. */

      else
	{
	if (*smtp_cmd_data++ != '#')
	  {
	  done = synprot_error(L_smtp_syntax_error, 501, NULL,
	    US"argument must begin with #");
	  break;
	  }
	etrn_command = US"exim -R";
	argv = CUSS child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE,
	  *queue_name ? 4 : 2,
	  US"-R", smtp_cmd_data,
	  US"-MCG", queue_name);
	}

      /* If we are host-testing, don't actually do anything. */

      if (host_checking)
	{
	HDEBUG(D_any)
	  {
	  debug_printf("ETRN command is: %s\n", etrn_command);
	  debug_printf("ETRN command execution skipped\n");
	  }
	if (user_msg == NULL) smtp_printf("250 OK\r\n", FALSE);
	  else smtp_user_msg(US"250", user_msg);
	break;
	}


      /* If ETRN queue runs are to be serialized, check the database to
      ensure one isn't already running. */

      if (smtp_etrn_serialize && !enq_start(etrn_serialize_key, 1))
	{
	smtp_printf("458 Already processing %s\r\n", FALSE, smtp_cmd_data);
	break;
	}

      /* Fork a child process and run the command. We don't want to have to
      wait for the process at any point, so set SIGCHLD to SIG_IGN before
      forking. It should be set that way anyway for external incoming SMTP,
      but we save and restore to be tidy. If serialization is required, we
      actually run the command in yet another process, so we can wait for it
      to complete and then remove the serialization lock. */

      oldsignal = signal(SIGCHLD, SIG_IGN);

      if ((pid = fork()) == 0)
	{
	smtp_input = FALSE;       /* This process is not associated with the */
	(void)fclose(smtp_in);    /* SMTP call any more. */
	(void)fclose(smtp_out);

	signal(SIGCHLD, SIG_DFL);      /* Want to catch child */

	/* If not serializing, do the exec right away. Otherwise, fork down
	into another process. */

	if (!smtp_etrn_serialize || (pid = fork()) == 0)
	  {
	  DEBUG(D_exec) debug_print_argv(argv);
	  exim_nullstd();                   /* Ensure std{in,out,err} exist */
	  execv(CS argv[0], (char *const *)argv);
	  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
	    etrn_command, strerror(errno));
	  _exit(EXIT_FAILURE);         /* paranoia */
	  }

	/* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
	is, we are in the first subprocess, after forking again. All we can do
	for a failing fork is to log it. Otherwise, wait for the 2nd process to
	complete, before removing the serialization. */

	if (pid < 0)
	  log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
	    "failed: %s", strerror(errno));
	else
	  {
	  int status;
	  DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
	    (int)pid);
	  (void)wait(&status);
	  DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
	    (int)pid);
	  }

	enq_end(etrn_serialize_key);
	_exit(EXIT_SUCCESS);
	}

      /* Back in the top level SMTP process. Check that we started a subprocess
      and restore the signal state. */

      if (pid < 0)
	{
	log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
	  strerror(errno));
	smtp_printf("458 Unable to fork process\r\n", FALSE);
	if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
	}
      else
	{
	if (user_msg == NULL) smtp_printf("250 OK\r\n", FALSE);
	  else smtp_user_msg(US"250", user_msg);
	}

      signal(SIGCHLD, oldsignal);
      break;


    case BADARG_CMD:
      done = synprot_error(L_smtp_syntax_error, 501, NULL,
	US"unexpected argument data");
      break;


    /* This currently happens only for NULLs, but could be extended. */

    case BADCHAR_CMD:
      done = synprot_error(L_smtp_syntax_error, 0, NULL,       /* Just logs */
	US"NUL character(s) present (shown as '?')");
      smtp_printf("501 NUL characters are not allowed in SMTP commands\r\n",
		  FALSE);
      break;


    case BADSYN_CMD:
    SYNC_FAILURE:
      if (smtp_inend >= smtp_inbuffer + IN_BUFFER_SIZE)
	smtp_inend = smtp_inbuffer + IN_BUFFER_SIZE - 1;
      c = smtp_inend - smtp_inptr;
      if (c > 150) c = 150;	/* limit logged amount */
      smtp_inptr[c] = 0;
      incomplete_transaction_log(US"sync failure");
      log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
	"(next input sent too soon: pipelining was%s advertised): "
	"rejected \"%s\" %s next input=\"%s\"",
	f.smtp_in_pipelining_advertised ? "" : " not",
	smtp_cmd_buffer, host_and_ident(TRUE),
	string_printing(smtp_inptr));
      smtp_notquit_exit(US"synchronization-error", US"554",
	US"SMTP synchronization error");
      done = 1;   /* Pretend eof - drops connection */
      break;


    case TOO_MANY_NONMAIL_CMD:
      s = smtp_cmd_buffer;
      while (*s != 0 && !isspace(*s)) s++;
      incomplete_transaction_log(US"too many non-mail commands");
      log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
	"nonmail commands (last was \"%.*s\")",  host_and_ident(FALSE),
	(int)(s - smtp_cmd_buffer), smtp_cmd_buffer);
      smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
      done = 1;   /* Pretend eof - drops connection */
      break;

#ifdef SUPPORT_PROXY
    case PROXY_FAIL_IGNORE_CMD:
      smtp_printf("503 Command refused, required Proxy negotiation failed\r\n", FALSE);
      break;
#endif

    default:
      if (unknown_command_count++ >= smtp_max_unknown_commands)
	{
	log_write(L_smtp_syntax_error, LOG_MAIN,
	  "SMTP syntax error in \"%s\" %s %s",
	  string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
	  US"unrecognized command");
	incomplete_transaction_log(US"unrecognized command");
	smtp_notquit_exit(US"bad-commands", US"500",
	  US"Too many unrecognized commands");
	done = 2;
	log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
	  "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
	  string_printing(smtp_cmd_buffer));
	}
      else
	done = synprot_error(L_smtp_syntax_error, 500, NULL,
	  US"unrecognized command");
      break;
    }

  /* This label is used by goto's inside loops that want to break out to
  the end of the command-processing loop. */

  COMMAND_LOOP:
  last_was_rej_mail = was_rej_mail;     /* Remember some last commands for */
  last_was_rcpt = was_rcpt;             /* protocol error handling */
  continue;
  }

return done - 2;  /* Convert yield values */
}
Unknown