;;; smtpmail.el --- simple SMTP protocol (RFC 821) for sending mail  -*- lexical-binding:t -*-

;; Copyright (C) 1995-1996, 2001-2018 Free Software Foundation, Inc.

;; Author: Tomoji Kagatani <kagatani@rbc.ncl.omron.co.jp>
;; Maintainer: Simon Josefsson <simon@josefsson.org>
;; w32 Maintainer: Brian D. Carlstrom <bdc@ai.mit.edu>
;; ESMTP support: Simon Leinen <simon@switch.ch>
;; Hacked by Mike Taylor, 11th October 1999 to add support for
;; automatically appending a domain to RCPT TO: addresses.
;; AUTH=LOGIN support: Stephen Cranefield <scranefield@infoscience.otago.ac.nz>
;; Keywords: mail

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; Send Mail to smtp host from smtpmail temp buffer.

;; Please add these lines in your .emacs(_emacs) or use customize.
;;
;;(setq send-mail-function 'smtpmail-send-it) ; if you use `mail'
;;(setq message-send-mail-function 'smtpmail-send-it) ; if you use message/Gnus
;;(setq smtpmail-smtp-server "YOUR SMTP HOST")
;;(setq smtpmail-local-domain "YOUR DOMAIN NAME")
;;(setq smtpmail-sendto-domain "YOUR DOMAIN NAME")
;;(setq smtpmail-debug-info t) ; only to debug problems

;; To queue mail, set `smtpmail-queue-mail' to t and use
;; `smtpmail-send-queued-mail' to send.

;; Modified by Stephen Cranefield <scranefield@infoscience.otago.ac.nz>,
;; 22/6/99, to support SMTP Authentication by the AUTH=LOGIN mechanism.
;; See http://help.netscape.com/products/server/messaging/3x/info/smtpauth.html
;; Rewritten by Simon Josefsson to use same credential variable as AUTH
;; support below.

;; Modified by Simon Josefsson <jas@pdc.kth.se>, 22/2/99, to support SMTP
;; Authentication by the AUTH mechanism.
;; See http://www.ietf.org/rfc/rfc2554.txt

;;; Code:

(require 'sendmail)
(require 'auth-source)
(autoload 'mail-strip-quoted-names "mail-utils")
(autoload 'message-make-date "message")
(autoload 'message-make-message-id "message")
(autoload 'rfc2104-hash "rfc2104")

;;;
(defgroup smtpmail nil
  "SMTP protocol for sending mail."
  :group 'mail)


(defcustom smtpmail-default-smtp-server nil
  "Specify default SMTP server.
This only has effect if you specify it before loading the smtpmail library."
  :type '(choice (const nil) string)
  :group 'smtpmail)

(defcustom smtpmail-smtp-server
  (or (getenv "SMTPSERVER") smtpmail-default-smtp-server)
  "The name of the host running SMTP server."
  :type '(choice (const nil) string)
  :group 'smtpmail)

(defcustom smtpmail-smtp-service 25
  "SMTP service port number.
The default value would be \"smtp\" or 25."
  :type '(choice (integer :tag "Port") (string :tag "Service"))
  :group 'smtpmail)

(defcustom smtpmail-smtp-user nil
  "User name to use when looking up credentials in the authinfo file.
If non-nil, only consider credentials for the specified user."
  :version "24.1"
  :type '(choice (const nil) string)
  :group 'smtpmail)

(defcustom smtpmail-local-domain nil
  "Local domain name without a host name.
If the function `system-name' returns the full internet address,
don't define this value."
  :type '(choice (const nil) string)
  :group 'smtpmail)

(defcustom smtpmail-stream-type nil
  "Type of SMTP connections to use.
This may be either nil (possibly upgraded to STARTTLS if possible),
or `starttls' (refuse to send if STARTTLS isn't available), or `plain'
\(never use STARTTLS), or `ssl' (to use TLS/SSL)."
  :version "24.1"
  :group 'smtpmail
  :type '(choice (const :tag "Possibly upgrade to STARTTLS" nil)
		 (const :tag "Always use STARTTLS" starttls)
		 (const :tag "Never use STARTTLS" plain)
		 (const :tag "Use TLS/SSL" ssl)))

(defcustom smtpmail-sendto-domain nil
  "Local domain name without a host name.
This is appended (with an @-sign) to any specified recipients which do
not include an @-sign, so that each RCPT TO address is fully qualified.
\(Some configurations of sendmail require this.)

Don't bother to set this unless you have get an error like:
	Sending failed; 501 <someone>: recipient address must contain a domain."
  :type '(choice (const nil) string)
  :group 'smtpmail)

(defcustom smtpmail-debug-info nil
  "Whether to print info in buffer *trace of SMTP session to <somewhere>*.
See also `smtpmail-debug-verb' which determines if the SMTP protocol should
be verbose as well."
  :type 'boolean
  :group 'smtpmail)

(defcustom smtpmail-debug-verb nil
  "Whether this library sends the SMTP VERB command or not.
The commands enables verbose information from the SMTP server."
  :type 'boolean
  :group 'smtpmail)

(defcustom smtpmail-code-conv-from nil
  "Coding system for encoding outgoing mail.
Used for the value of `sendmail-coding-system' when
`select-message-coding-system' is called."
  :type 'coding-system
  :group 'smtpmail)

(defcustom smtpmail-queue-mail nil
  "Non-nil means mail is queued; otherwise it is sent immediately.
If queued, it is stored in the directory `smtpmail-queue-dir'
and sent with `smtpmail-send-queued-mail'."
  :type 'boolean
  :group 'smtpmail)

(defcustom smtpmail-queue-dir "~/Mail/queued-mail/"
  "Directory where `smtpmail.el' stores queued mail."
  :type 'directory
  :group 'smtpmail)

(defcustom smtpmail-warn-about-unknown-extensions nil
  "If set, print warnings about unknown SMTP extensions.
This is mainly useful for development purposes, to learn about
new SMTP extensions that might be useful to support."
  :type 'boolean
  :version "21.1"
  :group 'smtpmail)

(defcustom smtpmail-queue-index-file "index"
  "File name of queued mail index.
This is relative to `smtpmail-queue-dir'."
  :type 'string
  :group 'smtpmail)

;; End of customizable variables.


(defvar smtpmail-address-buffer)
(defvar smtpmail-recipient-address-list)

(defvar smtpmail-queue-counter 0)

;; Buffer-local variable.
(defvar smtpmail-read-point)

(defvar smtpmail-auth-supported '(cram-md5 plain login)
  "List of supported SMTP AUTH mechanisms.
The list is in preference order.
Every element should have a matching `cl-defmethod' for
for `smtpmail-try-auth-method'.")

(defvar smtpmail-mail-address nil
  "Value to use for envelope-from address for mail from ambient buffer.")

;;;###autoload
(defun smtpmail-send-it ()
  (let ((errbuf (if mail-interactive
		    (generate-new-buffer " smtpmail errors")
		  0))
	(tembuf (generate-new-buffer " smtpmail temp"))
	(case-fold-search nil)
	delimline
	result
	(mailbuf (current-buffer))
        ;; Examine this variable now, so that
	;; local binding in the mail buffer will take effect.
	(smtpmail-mail-address
         (or (and mail-specify-envelope-from (mail-envelope-from))
             (let ((from (mail-fetch-field "from")))
	       (and from
		    (cadr (mail-extract-address-components from))))
	     (smtpmail-user-mail-address)))
	(smtpmail-code-conv-from
	 (if enable-multibyte-characters
	     (let ((sendmail-coding-system smtpmail-code-conv-from))
	       (select-message-coding-system)))))
    (unwind-protect
	(with-current-buffer tembuf
	  (erase-buffer)
	  ;; Use the same `buffer-file-coding-system' as in the mail
	  ;; buffer, otherwise any `write-region' invocations (e.g., in
	  ;; mail-do-fcc below) will annoy with asking for a suitable
	  ;; encoding.
	  (set-buffer-file-coding-system smtpmail-code-conv-from nil t)
	  (insert-buffer-substring mailbuf)
	  (goto-char (point-max))
	  ;; require one newline at the end.
	  (or (= (preceding-char) ?\n)
	      (insert ?\n))
	  ;; Change header-delimiter to be what sendmail expects.
	  (mail-sendmail-undelimit-header)
	  (setq delimline (point-marker))
          ;; (sendmail-synch-aliases)
	  (if mail-aliases
	      (expand-mail-aliases (point-min) delimline))
	  (goto-char (point-min))
	  ;; ignore any blank lines in the header
	  (while (and (re-search-forward "\n\n\n*" delimline t)
		      (< (point) delimline))
	    (replace-match "\n"))
	  (let ((case-fold-search t))
	    ;; We used to process Resent-... headers here,
	    ;; but it was not done properly, and the job
	    ;; is done correctly in `smtpmail-deduce-address-list'.
	    ;; Don't send out a blank subject line
	    (goto-char (point-min))
	    (if (re-search-forward "^Subject:\\([ \t]*\n\\)+\\b" delimline t)
		(replace-match "")
	      ;; This one matches a Subject just before the header delimiter.
	      (if (and (re-search-forward "^Subject:\\([ \t]*\n\\)+" delimline t)
		       (= (match-end 0) delimline))
		  (replace-match "")))
	    ;; Put the "From:" field in unless for some odd reason
	    ;; they put one in themselves.
	    (goto-char (point-min))
	    (if (not (re-search-forward "^From:" delimline t))
		(let* ((login smtpmail-mail-address)
		       (fullname (user-full-name)))
		  (cond ((eq mail-from-style 'angles)
			 (insert "From: " fullname)
			 (let ((fullname-start (+ (point-min) 6))
			       (fullname-end (point-marker)))
			   (goto-char fullname-start)
			   ;; Look for a character that cannot appear unquoted
			   ;; according to RFC 822.
			   (if (re-search-forward "[^- !#-'*+/-9=?A-Z^-~]"
						  fullname-end 1)
			       (progn
				 ;; Quote fullname, escaping specials.
				 (goto-char fullname-start)
				 (insert "\"")
				 (while (re-search-forward "[\"\\]"
							   fullname-end 1)
				   (replace-match "\\\\\\&" t))
				 (insert "\""))))
			 (insert " <" login ">\n"))
			((eq mail-from-style 'parens)
			 (insert "From: " login " (")
			 (let ((fullname-start (point)))
			   (insert fullname)
			   (let ((fullname-end (point-marker)))
			     (goto-char fullname-start)
			     ;; RFC 822 says \ and nonmatching parentheses
			     ;; must be escaped in comments.
			     ;; Escape every instance of ()\ ...
			     (while (re-search-forward "[()\\]" fullname-end 1)
			       (replace-match "\\\\\\&" t))
			     ;; ... then undo escaping of matching parentheses,
			     ;; including matching nested parentheses.
			     (goto-char fullname-start)
			     (while (re-search-forward
				     "\\(\\=\\|[^\\]\\(\\\\\\\\\\)*\\)\\\\(\\(\\([^\\]\\|\\\\\\\\\\)*\\)\\\\)"
				     fullname-end 1)
			       (replace-match "\\1(\\3)" t)
			       (goto-char fullname-start))))
			 (insert ")\n"))
			((null mail-from-style)
			 (insert "From: " login "\n")))))
	    ;; Insert a `Message-Id:' field if there isn't one yet.
	    (goto-char (point-min))
	    (unless (re-search-forward "^Message-Id:" delimline t)
	      (insert "Message-Id: " (message-make-message-id) "\n"))
	    ;; Insert a `Date:' field if there isn't one yet.
	    (goto-char (point-min))
	    (unless (re-search-forward "^Date:" delimline t)
	      (insert "Date: " (message-make-date) "\n"))
	    ;; Possibly add a MIME header for the current coding system
	    (let (charset)
	      (goto-char (point-min))
	      (and (eq mail-send-nonascii 'mime)
		   (not (re-search-forward "^MIME-version:" delimline t))
		   (progn (skip-chars-forward "\0-\177")
			  (/= (point) (point-max)))
		   smtpmail-code-conv-from
		   (setq charset
			 (coding-system-get smtpmail-code-conv-from
					    'mime-charset))
		   (goto-char delimline)
		   (insert "MIME-version: 1.0\n"
			   "Content-type: text/plain; charset="
			   (symbol-name charset)
			   "\nContent-Transfer-Encoding: 8bit\n")))
	    ;; Insert an extra newline if we need it to work around
	    ;; Sun's bug that swallows newlines.
	    (goto-char (1+ delimline))
	    (if (eval mail-mailer-swallows-blank-line)
		(newline))
	    ;; Find and handle any Fcc fields.
	    (goto-char (point-min))
	    (if (re-search-forward "^Fcc:" delimline t)
		;; Force `mail-do-fcc' to use the encoding of the mail
		;; buffer to encode outgoing messages on Fcc files.
		(let ((coding-system-for-write
		       ;; mbox files must have Unix EOLs.
		       (coding-system-change-eol-conversion
			smtpmail-code-conv-from 'unix)))
		  (mail-do-fcc delimline)))
	    (if mail-interactive
		(with-current-buffer errbuf
		  (erase-buffer))))
	  ;; Encode the header according to RFC2047.
	  (mail-encode-header (point-min) delimline)
	  ;;
	  (setq smtpmail-address-buffer (generate-new-buffer "*smtp-mail*"))
	  (setq smtpmail-recipient-address-list
                (smtpmail-deduce-address-list tembuf (point-min) delimline))
	  (kill-buffer smtpmail-address-buffer)

	  (smtpmail-do-bcc delimline)
          ;; Send or queue
	  (if (not smtpmail-queue-mail)
	      (if (not (null smtpmail-recipient-address-list))
		  (when (setq result
			      (smtpmail-via-smtp
			       smtpmail-recipient-address-list tembuf))
		    (error "Sending failed: %s" result))
		(error "Sending failed; no recipients"))
	    (let* ((file-data
		    (expand-file-name
		     (format "%s_%i"
			     (format-time-string "%Y-%m-%d_%H:%M:%S")
			     (setq smtpmail-queue-counter
				   (1+ smtpmail-queue-counter)))
		     smtpmail-queue-dir))
		   (file-data (convert-standard-filename file-data))
		   (file-elisp (concat file-data ".el"))
		   (buffer-data (create-file-buffer file-data))
		   (buffer-elisp (create-file-buffer file-elisp))
		   (buffer-scratch "*queue-mail*"))
	      (unless (file-exists-p smtpmail-queue-dir)
		(make-directory smtpmail-queue-dir t))
	      (with-current-buffer buffer-data
		(erase-buffer)
		(set-buffer-file-coding-system
		 ;; We will be reading the file with no-conversion in
		 ;; smtpmail-send-queued-mail below, so write it out
		 ;; with Unix EOLs.
		 (coding-system-change-eol-conversion
		  (or smtpmail-code-conv-from 'undecided)
		  'unix)
		 nil t)
		(insert-buffer-substring tembuf)
		(write-file file-data)
		(set-buffer buffer-elisp)
		(erase-buffer)
		(insert (concat
			 "(setq smtpmail-recipient-address-list '"
			 (prin1-to-string smtpmail-recipient-address-list)
			 ")\n"))
		(write-file file-elisp)
		(set-buffer (generate-new-buffer buffer-scratch))
		(insert (concat file-data "\n"))
		(append-to-file (point-min)
				(point-max)
                                (expand-file-name smtpmail-queue-index-file
                                                  smtpmail-queue-dir)))
	      (kill-buffer buffer-scratch)
	      (kill-buffer buffer-data)
	      (kill-buffer buffer-elisp))))
      (kill-buffer tembuf)
      (if (bufferp errbuf)
	  (kill-buffer errbuf)))))

;;;###autoload
(defun smtpmail-send-queued-mail ()
  "Send mail that was queued as a result of setting `smtpmail-queue-mail'."
  (interactive)
  (with-temp-buffer
    ;; Get index, get first mail, send it, update index, get second
    ;; mail, send it, etc...
    (let ((file-msg "")
          (qfile (expand-file-name smtpmail-queue-index-file
                                   smtpmail-queue-dir))
	  result)
      (insert-file-contents qfile)
      (goto-char (point-min))
      (while (not (eobp))
	(setq file-msg (buffer-substring (point) (line-end-position)))
	(load file-msg)
	;; Insert the message literally: it is already encoded as per
	;; the MIME headers, and code conversions might guess the
	;; encoding wrongly.
	(with-temp-buffer
	  (let ((coding-system-for-read 'no-conversion))
	    (insert-file-contents file-msg))
          (let ((smtpmail-mail-address
                 (or (and mail-specify-envelope-from (mail-envelope-from))
                     user-mail-address)))
            (if (not (null smtpmail-recipient-address-list))
                (when (setq result (smtpmail-via-smtp
				    smtpmail-recipient-address-list
				    (current-buffer)))
		  (error "Sending failed: %s" result))
              (error "Sending failed; no recipients"))))
	(delete-file file-msg)
	(delete-file (concat file-msg ".el"))
	(delete-region (point-at-bol) (point-at-bol 2)))
      (write-region (point-min) (point-max) qfile))))

(defun smtpmail-fqdn ()
  (if smtpmail-local-domain
      (concat (system-name) "." smtpmail-local-domain)
    (system-name)))

(defsubst smtpmail-cred-server (cred)
  (nth 0 cred))

(defsubst smtpmail-cred-port (cred)
  (nth 1 cred))

(defsubst smtpmail-cred-key (cred)
  (nth 2 cred))

(defsubst smtpmail-cred-user (cred)
  (nth 2 cred))

(defsubst smtpmail-cred-cert (cred)
  (nth 3 cred))

(defsubst smtpmail-cred-passwd (cred)
  (nth 3 cred))

(defun smtpmail-find-credentials (cred server port)
  (catch 'done
    (let ((l cred) el)
      (while (setq el (pop l))
	(when (and (equal server (smtpmail-cred-server el))
		   (equal port (smtpmail-cred-port el)))
	  (throw 'done el))))))

(defun smtpmail-maybe-append-domain (recipient)
  (if (or (not smtpmail-sendto-domain)
	  (string-match "@" recipient))
      recipient
    (concat recipient "@" smtpmail-sendto-domain)))

(defun smtpmail-intersection (list1 list2)
  (let ((result nil))
    (dolist (el2 list2)
      (when (memq el2 list1)
	(push el2 result)))
    (nreverse result)))

(defun smtpmail-command-or-throw (process string &optional code)
  (let (ret)
    (smtpmail-send-command process string)
    (unless (smtpmail-ok-p (setq ret (smtpmail-read-response process))
			   code)
      (throw 'done (format "%s in response to %s"
			   (smtpmail-response-text ret)
			   string)))
    ret))

(defun smtpmail-try-auth-methods (process supported-extensions host port
					  &optional ask-for-password)
  (setq port
	(if port
	    (format "%s" port)
	  "smtp"))
  (let* ((mechs (cdr-safe (assoc 'auth supported-extensions)))
	 (mech (car (smtpmail-intersection mechs smtpmail-auth-supported)))
	 (auth-source-creation-prompts
          '((user  . "SMTP user name for %h: ")
            (secret . "SMTP password for %u@%h: ")))
         (auth-info (car
		     (auth-source-search
		      :host host
		      :port port
		      :user smtpmail-smtp-user
		      :max 1
		      :require (and ask-for-password
				    '(:user :secret))
		      :create ask-for-password)))
         (user (plist-get auth-info :user))
         (password (plist-get auth-info :secret))
	 (save-function (and ask-for-password
			     (plist-get auth-info :save-function))))
    (when (functionp password)
      (setq password (funcall password)))
    (when (and user
	       (not password))
      ;; The user has stored the user name, but not the password, so
      ;; ask for the password, even if we're not forcing that through
      ;; `ask-for-password'.
      (setq auth-info
	    (car
	     (auth-source-search
	      :max 1
	      :host host
	      :port port
	      :user smtpmail-smtp-user
	      :require '(:user :secret)
	      :create t))
	    password (plist-get auth-info :secret)))
    (when (functionp password)
      (setq password (funcall password)))
    (let ((result (catch 'done
                    (if (and mech user password)
		        (smtpmail-try-auth-method process mech user password)
                      ;; No mechanism, or no credentials.
                      mech))))
      (if (stringp result)
	  (progn
	    (auth-source-forget+ :host host :port port)
	    (throw 'done result))
	(when save-function
	  (funcall save-function))
	result))))

(cl-defgeneric smtpmail-try-auth-method (_process mech _user _password)
  "Perform authentication of type MECH for USER with PASSWORD.
MECH should be one of the values in `smtpmail-auth-supported'.
USER and PASSWORD should be non-nil."
  (error "Mechanism %S not implemented" mech))

(cl-defmethod smtpmail-try-auth-method
  (process (_mech (eql cram-md5)) user password)
  (let ((ret (smtpmail-command-or-throw process "AUTH CRAM-MD5")))
    (when (eq (car ret) 334)
      (let* ((challenge (substring (cadr ret) 4))
	     (decoded (base64-decode-string challenge))
	     (hash (rfc2104-hash 'md5 64 16 password decoded))
	     (response (concat user " " hash))
	     ;; Osamu Yamane <yamane@green.ocn.ne.jp>:
	     ;; SMTP auth fails because the SMTP server identifies
	     ;; only the first part of the string (delimited by
	     ;; new line characters) as a response from the
	     ;; client, and the rest as distinct commands.

	     ;; In my case, the response string is 80 characters
	     ;; long.  Without the no-line-break option for
	     ;; `base64-encode-string', only the first 76 characters
	     ;; are taken as a response to the server, and the
	     ;; authentication fails.
	     (encoded (base64-encode-string response t)))
	(smtpmail-command-or-throw process encoded)))))

(cl-defmethod smtpmail-try-auth-method
  (process (_mech (eql login)) user password)
  (smtpmail-command-or-throw process "AUTH LOGIN")
  (smtpmail-command-or-throw process (base64-encode-string user t))
  (smtpmail-command-or-throw process (base64-encode-string password t)))

(cl-defmethod smtpmail-try-auth-method
  (process (_mech (eql plain)) user password)
  ;; We used to send an empty initial request, and wait for an
  ;; empty response, and then send the password, but this
  ;; violate a SHOULD in RFC 2222 paragraph 5.1.  Note that this
  ;; is not sent if the server did not advertise AUTH PLAIN in
  ;; the EHLO response.  See RFC 2554 for more info.
  (smtpmail-command-or-throw
   process
   (concat "AUTH PLAIN "
	   (base64-encode-string (concat "\0" user "\0" password) t))
   235))

(defun smtpmail-response-code (string)
  (when string
    (with-temp-buffer
      (insert string)
      (goto-char (point-min))
      (and (re-search-forward "^\\([0-9]+\\) " nil t)
	   (string-to-number (match-string 1))))))

(defun smtpmail-ok-p (response &optional code)
  (and (car response)
       (integerp (car response))
       (< (car response) 400)
       (or (null code)
	   (= code (car response)))))

(defun smtpmail-response-text (response)
  (mapconcat 'identity (cdr response) "\n"))

(defun smtpmail-query-smtp-server ()
  "Query for an SMTP server and try to contact it.
If the contact succeeds, customizes and saves `smtpmail-smtp-server'
and `smtpmail-smtp-service'.  This tries standard SMTP ports, and if
none works asks you to supply one.  If you know that you need to use
a non-standard port, you can set `smtpmail-smtp-service' in advance.
Returns an error if the server cannot be contacted."
  (let ((server (read-string "Outgoing SMTP mail server: "))
	(ports '(25 587))
	stream port prompted)
    (when (and smtpmail-smtp-service
	       (not (member smtpmail-smtp-service ports)))
      (push smtpmail-smtp-service ports))
    (while (and (not smtpmail-smtp-server)
		(setq port (pop ports)))
      (if (not (setq stream (condition-case ()
				(open-network-stream "smtp" nil server port)
			      (quit nil)
			      (error nil))))
	  ;; We've used up the list of default ports, so query the user.
	  (when (and (not ports)
		     (not prompted))
	    (push (read-number (format "Port number to use when contacting %s? "
				       server))
		  ports)
	    (setq prompted t))
	(customize-save-variable 'smtpmail-smtp-server server)
	(customize-save-variable 'smtpmail-smtp-service port)
	(delete-process stream)))
    (unless smtpmail-smtp-server
      (error "Couldn't contact an SMTP server"))))

(defun smtpmail-user-mail-address ()
  "Return `user-mail-address' if it's a valid email address."
  (and user-mail-address
       (let ((parts (split-string user-mail-address "@")))
	 (and (= (length parts) 2)
	      ;; There's a dot in the domain name.
	      (string-match "\\." (cadr parts))
	      user-mail-address))))

(defun smtpmail-via-smtp (recipient smtpmail-text-buffer
				    &optional ask-for-password)
  (unless smtpmail-smtp-server
    (smtpmail-query-smtp-server))
  (let ((process nil)
	(host (or smtpmail-smtp-server
		  (error "`smtpmail-smtp-server' not defined")))
	(port smtpmail-smtp-service)
        ;; `smtpmail-mail-address' should be set to the appropriate
        ;; buffer-local value by the caller, but in case not:
        (envelope-from
	 (or smtpmail-mail-address
	     (and mail-specify-envelope-from
		  (mail-envelope-from))
	     (let ((from (mail-fetch-field "from")))
	       (and from
		    (cadr (mail-extract-address-components from))))
	     (smtpmail-user-mail-address)))
	process-buffer
	result
	auth-mechanisms
	(supported-extensions '()))
    (unwind-protect
	(catch 'done
	  ;; get or create the trace buffer
	  (setq process-buffer
		(get-buffer-create
		 (format "*trace of SMTP session to %s*" host)))

	  ;; clear the trace buffer of old output
	  (with-current-buffer process-buffer
	    (setq buffer-undo-list t)
	    (erase-buffer))

	  ;; Open the connection to the server.
          ;; FIXME: Should we use raw-text-dos coding system to handle the r\n
          ;; for us?
	  (let ((coding-system-for-read 'binary)
		(coding-system-for-write 'binary))
	    (setq result
		  (open-network-stream
		   "smtpmail" process-buffer host port
		   :type smtpmail-stream-type
		   :return-list t
		   :warn-unless-encrypted ask-for-password
		   :capability-command (format "EHLO %s\r\n" (smtpmail-fqdn))
		   :end-of-command "^[0-9]+ .*\r\n"
		   :success "^2.*\n"
		   :always-query-capabilities t
		   :starttls-function
		   (lambda (capabilities)
		     (and (string-match "[ -]STARTTLS" capabilities)
			  "STARTTLS\r\n"))
		   :client-certificate t
		   :use-starttls-if-possible t)))

	  ;; If we couldn't access the server at all, we give up.
	  (unless (setq process (car result))
	    (throw 'done (if (plist-get (cdr result) :error)
			     (plist-get (cdr result) :error)
			   "Unable to contact server")))

	  ;; set the send-filter
	  (set-process-filter process 'smtpmail-process-filter)

	  (let* ((greeting (plist-get (cdr result) :greeting))
		 (code (smtpmail-response-code greeting)))
	    (unless code
	      (throw 'done (format "No greeting: %s" greeting)))
	    (when (>= code 400)
	      (throw 'done (format "Connection not allowed: %s" greeting))))

	  (with-current-buffer process-buffer
            (set-process-coding-system process 'raw-text-unix 'raw-text-unix)
	    (setq-local smtpmail-read-point (point-min))

	    (let* ((capabilities (plist-get (cdr result) :capabilities))
		   (code (smtpmail-response-code capabilities)))
	      (if (or (null code)
		      (>= code 400))
		  ;; The server didn't accept EHLO, so we fall back on HELO.
		  (smtpmail-command-or-throw
		   process (format "HELO %s" (smtpmail-fqdn)))
		;; EHLO was successful, so we parse the extensions.
		(dolist (line (delete
			       ""
			       (split-string
				(plist-get (cdr result) :capabilities)
				"\r\n")))
		  (let ((name
			 (with-case-table ascii-case-table ;FIXME: Why?
			   (mapcar (lambda (s) (intern (downcase s)))
				   (split-string (substring line 4) "[ ]")))))
		    (when (= (length name) 1)
		      (setq name (car name)))
		    (when name
		      (cond ((memq (if (consp name) (car name) name)
				   '(verb xvrb 8bitmime onex xone
					  expn size dsn etrn
					  enhancedstatuscodes
					  help xusr
					  auth=login auth starttls))
			     (setq supported-extensions
				   (cons name supported-extensions)))
			    (smtpmail-warn-about-unknown-extensions
			     (message "Unknown extension %s" name))))))))

	    (setq auth-mechanisms
		  (smtpmail-try-auth-methods
		   process supported-extensions host port
		   ask-for-password))

	    (when (or (member 'onex supported-extensions)
		      (member 'xone supported-extensions))
	      (smtpmail-command-or-throw process (format "ONEX")))

	    (when (and smtpmail-debug-verb
		       (or (member 'verb supported-extensions)
			   (member 'xvrb supported-extensions)))
	      (smtpmail-command-or-throw process (format "VERB")))

	    (when (member 'xusr supported-extensions)
	      (smtpmail-command-or-throw process (format "XUSR")))

	    ;; MAIL FROM:<sender>
	    (let ((size-part
		   (if (or (member 'size supported-extensions)
			   (assoc 'size supported-extensions))
		       (format " SIZE=%d"
			       (with-current-buffer smtpmail-text-buffer
				 ;; size estimate:
				 (+ (- (point-max) (point-min))
				    ;; Add one byte for each change-of-line
				    ;; because of CR-LF representation:
				    (count-lines (point-min) (point-max)))))
		     ""))
		  (body-part
		   (if (member '8bitmime supported-extensions)
		       ;; FIXME:
		       ;; Code should be added here that transforms
		       ;; the contents of the message buffer into
		       ;; something the receiving SMTP can handle.
		       ;; For a receiver that supports 8BITMIME, this
		       ;; may mean converting BINARY to BASE64, or
		       ;; adding Content-Transfer-Encoding and the
		       ;; other MIME headers.  The code should also
		       ;; return an indication of what encoding the
		       ;; message buffer is now, i.e. ASCII or
		       ;; 8BITMIME.
		       (if nil
			   " BODY=8BITMIME"
			 "")
		     "")))
	      (smtpmail-send-command
	       process (format "MAIL FROM:<%s>%s%s"
			       envelope-from size-part body-part))
	      (cond
	       ((smtpmail-ok-p (setq result (smtpmail-read-response process)))
		;; Success.
		)
	       ((and auth-mechanisms
		     (not ask-for-password)
		     (eq (car result) 530))
		;; We got a "530 auth required", so we close and try
		;; again, this time asking the user for a password.
		;; We ignore any errors here, because some MTAs just
		;; close the connection immediately after giving the
		;; error message.
		(ignore-errors
		  (smtpmail-send-command process "QUIT")
		  (smtpmail-read-response process))
		(delete-process process)
		(setq process nil)
		(throw 'done
		       (smtpmail-via-smtp recipient smtpmail-text-buffer t)))
	       (t
		;; Return the error code.
		(throw 'done
		       (smtpmail-response-text result)))))

	    ;; RCPT TO:<recipient>
	    (let ((n 0))
	      (while (not (null (nth n recipient)))
		(smtpmail-send-command
		 process (format "RCPT TO:<%s>"
				 (smtpmail-maybe-append-domain
				  (nth n recipient))))
		(cond
		 ((smtpmail-ok-p (setq result (smtpmail-read-response process)))
		  ;; Success.
		  nil)
		 ((and auth-mechanisms
		       (not ask-for-password)
		       (integerp (car result))
		       (>= (car result) 550)
		       (<= (car result) 554))
		  ;; We got a "550 relay not permitted" (or the like),
		  ;; and the server accepts credentials, so we try
		  ;; again, but ask for a password first.
		  (smtpmail-send-command process "QUIT")
		  (smtpmail-read-response process)
		  (delete-process process)
		  (setq process nil)
		  (throw 'done
			 (smtpmail-via-smtp recipient smtpmail-text-buffer t)))
		 (t
		  ;; Return the error code.
		  (throw 'done
			 (smtpmail-response-text result))))
		(setq n (1+ n))))

	    ;; Send the contents.
	    (smtpmail-command-or-throw process "DATA")
	    (smtpmail-send-data process smtpmail-text-buffer)
	    ;; Return success.
	    nil))
      (when (and process
		 (buffer-live-p process-buffer))
	(with-current-buffer (process-buffer process)
	  (smtpmail-send-command process "QUIT")
	  (smtpmail-read-response process)
	  (delete-process process)
	  (unless smtpmail-debug-info
	    (kill-buffer process-buffer)))))))


(defun smtpmail-process-filter (process output)
  (with-current-buffer (process-buffer process)
    (goto-char (point-max))
    (insert output)
    (set-marker (process-mark process) (point))))

(defun smtpmail-read-response (process)
  (let ((case-fold-search nil)
	(response-strings nil)
	(response-continue t)
	(return-value '(nil ()))
	match-end)
    (catch 'done
      (while response-continue
	(goto-char smtpmail-read-point)
	(while (not (search-forward "\r\n" nil t))
	  (unless (memq (process-status process) '(open run))
	    (throw 'done nil))
	  (accept-process-output process)
	  (goto-char smtpmail-read-point))

	(setq match-end (point))
	(setq response-strings
	      (cons (buffer-substring smtpmail-read-point (- match-end 2))
		    response-strings))

	(goto-char smtpmail-read-point)
	(if (looking-at "[0-9]+ ")
	    (let ((begin (match-beginning 0))
		  (end (match-end 0)))
	      (if smtpmail-debug-info
		  (message "%s" (car response-strings)))

	      (setq smtpmail-read-point match-end)

	      ;; ignore lines that start with "0"
	      (if (looking-at "0[0-9]+ ")
		  nil
		(setq response-continue nil)
		(setq return-value
		      (cons (string-to-number
			     (buffer-substring begin end))
			    (nreverse response-strings)))))

	  (if (looking-at "[0-9]+-")
	      (progn (if smtpmail-debug-info
			 (message "%s" (car response-strings)))
		     (setq smtpmail-read-point match-end)
		     (setq response-continue t))
	    (progn
	      (setq smtpmail-read-point match-end)
	      (setq response-continue nil)
	      (setq return-value
		    (cons nil (nreverse response-strings)))))))
      (setq smtpmail-read-point match-end))
    return-value))


(defun smtpmail-send-command (process command)
  (goto-char (point-max))
  (if (string-match "\\`AUTH [A-Z]+ " command)
      (insert (match-string 0 command) "<omitted>\r\n")
    (insert command "\r\n"))
  (setq smtpmail-read-point (point))
  (process-send-string process (concat command "\r\n")))

(defun smtpmail-send-data-1 (process data)
  (goto-char (point-max))

  (if (and (multibyte-string-p data)
	   smtpmail-code-conv-from)
      (setq data (encode-coding-string data smtpmail-code-conv-from)))

  (if smtpmail-debug-info
      (insert data "\r\n"))

  (setq smtpmail-read-point (point))
  ;; Escape "." at start of a line
  (if (eq (string-to-char data) ?.)
      (process-send-string process "."))
  (process-send-string process data)
  (process-send-string process "\r\n"))

(defun smtpmail-send-data (process buffer)
  (let ((data-continue t)
        (pr (with-current-buffer buffer
              (make-progress-reporter "Sending email "
                                      (point-min) (point-max))))
        sending-data)
    (with-current-buffer buffer
      (goto-char (point-min)))
    (while data-continue
      (with-current-buffer buffer
        (progress-reporter-update pr (point))
        (setq sending-data (buffer-substring (point-at-bol) (point-at-eol)))
	(end-of-line 2)
        (setq data-continue (not (eobp))))
      (smtpmail-send-data-1 process sending-data))
    ;; DATA end "."
    (smtpmail-command-or-throw process ".")
    (progress-reporter-done pr)))

(defun smtpmail-deduce-address-list (smtpmail-text-buffer header-start header-end)
  "Get address list suitable for smtp RCPT TO: <address>."
  (unwind-protect
      (with-current-buffer smtpmail-address-buffer
	(erase-buffer)
	(let ((case-fold-search t)
              (simple-address-list "")
              this-line
              this-line-end
              addr-regexp)
	  (insert-buffer-substring smtpmail-text-buffer header-start header-end)
	  (goto-char (point-min))
	  ;; RESENT-* fields should stop processing of regular fields.
	  (save-excursion
	    (setq addr-regexp
		  (if (re-search-forward "^Resent-\\(To\\|Cc\\|Bcc\\):"
					 header-end t)
		      "^Resent-\\(To\\|Cc\\|Bcc\\):"
		    "^\\(To:\\|Cc:\\|Bcc:\\)")))

	  (while (re-search-forward addr-regexp header-end t)
	    (replace-match "")
	    (setq this-line (match-beginning 0))
	    (forward-line 1)
	    ;; get any continuation lines
	    (while (and (looking-at "^[ \t]+") (< (point) header-end))
	      (forward-line 1))
	    (setq this-line-end (point-marker))
	    (setq simple-address-list
		  (concat simple-address-list " "
			  (mail-strip-quoted-names (buffer-substring this-line this-line-end)))))
	  (erase-buffer)
	  (insert " " simple-address-list "\n")
	  (subst-char-in-region (point-min) (point-max) 10 ?  t) ; newline --> blank
	  (subst-char-in-region (point-min) (point-max) ?, ?  t) ; comma   --> blank
	  (subst-char-in-region (point-min) (point-max)  9 ?  t) ; tab     --> blank

	  (goto-char (point-min))
	  ;; tidiness in case hook is not robust when it looks at this
	  (while (re-search-forward "[ \t]+" header-end t) (replace-match " "))

	  (goto-char (point-min))
	  (let (recipient-address-list)
	    (while (re-search-forward " \\([^ ]+\\) " (point-max) t)
	      (backward-char 1)
	      (setq recipient-address-list (cons (buffer-substring (match-beginning 1) (match-end 1))
						 recipient-address-list)))
	    (setq smtpmail-recipient-address-list recipient-address-list))))))

(defun smtpmail-do-bcc (header-end)
  "Delete [Resent-]Bcc: and their continuation lines from the header area.
There may be multiple Bcc: lines, and each may have arbitrarily
many continuation lines."
  (let ((case-fold-search t))
    (save-excursion
      (goto-char (point-min))
      ;; iterate over all Bcc: lines
      (while (re-search-forward "^\\(RESENT-\\)?Bcc:" header-end t)
	(delete-region (match-beginning 0)
		       (progn (forward-line 1) (point)))
	;; get rid of any continuation lines
	(while (and (looking-at "^[ \t].*\n") (< (point) header-end))
	  (replace-match ""))))))

(provide 'smtpmail)

;;; smtpmail.el ends here