(chicken string)
(chicken pathname)
(chicken file)
+ (chicken time)
(chicken time posix)
- srfi-1 srfi-13 matchable)
+ (chicken process)
+ (chicken process-context)
+ (chicken process-context posix)
+ (chicken condition)
+ srfi-1 srfi-13 matchable base64)
(define lambdamail-version "0.0.1")
-(define-record config port)
-(define-record message to from text helo)
-(define (make-empty-message) (make-message "" "" "" ""))
+(define-record config host port spool-dir user group)
+(define-record message to from text helo user password)
+(define (make-empty-message) (make-message "" "" "" "" "" ""))
+
+(define outbound-mail-queue '())
+
+
+;;; Server initialization
+;;
+
+(define (drop-privs config)
+ (let ((uid (config-user config))
+ (gid (config-group config)))
+ (if (not (null? gid)) ; Group first, since only root can switch groups.
+ (set! (current-group-id) gid))
+ (if (not (null? uid))
+ (set! (current-user-id) uid))))
(define (run-server config)
(set-buffering-mode! (current-output-port) #:line)
(let ((listener (tcp-listen (config-port config) 10 "::")))
- (print "LambdaMail listening on port " (config-port config) " ...")
+ (print "LambdaMail v" lambdamail-version
+ " listening on port " (config-port config) " ...")
+ (print "(Host name: " (config-host config)
+ ", Spool dir: " (config-spool-dir config) ")")
+ (drop-privs config)
(server-loop listener config)))
-
+
+
+;;; Main server loop
+;;
+
(define (server-loop listener config)
(let-values (((in-port out-port) (tcp-accept listener)))
(let-values (((local-ip remote-ip) (tcp-addresses in-port)))
(print "Accepted connection from " remote-ip " on " (seconds->string)))
- (write-line (conc "Welcome to lambamail v" lambdamail-version) out-port)
- (process-smtp in-port out-port)
- (print "Connection terminated.")
+ (condition-case
+ (let ((smtp-session (make-smtp-session in-port out-port config)))
+ (smtp-session 'greet)
+ (process-smtp smtp-session config))
+ (o (exn)
+ (print-error-message o)))
+ (print "Terminating connection.")
(close-input-port in-port)
(close-output-port out-port))
+ (print "Attempting delivery of " (length outbound-mail-queue) " mail items.")
+ (set! outbound-mail-queue
+ (filter (lambda (msg) (not (deliver-message msg config)))
+ outbound-mail-queue))
(server-loop listener config))
-(define (smtp-reply reply out-port)
- (write-line (conc reply "\r\n") out-port))
-
-(define (smtp-ok out-port)
- (smtp-reply "250 OK" out-port))
-
-(define (smtp-close out-port)
- (smtp-reply "221 Closing transmission channel" out-port))
-
-(define (smtp-no out-port)
- (smtp-reply "502 Command not implemented" out-port))
-
-(define (process-smtp in-port out-port)
- (let loop ((msg (make-empty-message))
- (line (string-downcase (read-line in-port))))
- (cond
- ((string-prefix? "helo" line)
- (message-helo-set! msg (string-drop line (string-length "helo")))
- (smtp-ok out-port)
- (loop msg (string-downcase (read-line in-port))))
- ((string-prefix? "mail from:" line)
- (message-from-set! msg (string-drop line (string-length "mail from:")))
- (smtp-ok out-port)
- (loop msg (string-downcase (read-line in-port))))
- ((string-prefix? "rcpt to:" line)
- (message-to-set! msg (string-drop line (string-length "rcpt to:")))
- (smtp-ok out-port)
- (loop msg (string-downcase (read-line in-port))))
- ((string-prefix? "data" line)
- (let text-loop ((text-line (read-line in-port))
- (text ""))
- (print "Received '" text-line "'")
- (if (string=? "." text-line)
- (message-text-set! msg text)
- (text-loop (read-line in-port)
- (conc text text-line))))
- (deliver-message msg)
- (smtp-ok out-port)
- (loop (make-empty-message)
- (string-downcase (read-line in-port))))
- ((string-prefix? "quit" line)
- (smtp-close out-port)
- 'done)
- (else
- (smtp-no out-port)))))
-
-(define (deliver-message msg)
- (print "Message delivered:")
- (print " * From: " (message-from msg))
- (print " * To: " (message-to msg))
- (print " * Text: " (message-text msg)))
-
-(define (test)
- (run-server (make-config 2525)))
-
-(test)
+;;; SMTP processing loop
+;;
+
+(define (make-smtp-session in-port out-port config)
+ (let ((smtp-say (lambda args (write-line (conc (apply conc args) "\r") out-port)))
+ (user "")
+ (password ""))
+ (lambda msg
+ (match msg
+ (('get-line) (read-line in-port))
+ (('set-user! u) (set! user u))
+ (('set-password! p) (set! password p))
+ (('user) user)
+ (('password) password)
+ (('auth-success) (smtp-say "235 Authentication successful"))
+ (('greet) (smtp-say "220 " (config-host config)
+ " LambdaMail v" lambdamail-version))
+ (('ok) (smtp-say "250 ok"))
+ (('ehlo host)
+ (smtp-say "250-" (config-host config) " Hello " host)
+ (smtp-say "250 AUTH PLAIN"))
+ (('intermediate) (smtp-say "354 intermediate"))
+ (('close) (smtp-say "221 closing transmission channel"))
+ (('not-implemented) (smtp-say "502 command not implemented"))))))
+
+(define (process-smtp smtp-session config)
+ (let loop ((msg (make-empty-message)))
+ (let ((line-orig (smtp-session 'get-line)))
+ (if (string? line-orig)
+ (let ((line (string-downcase line-orig)))
+ (print "got " line-orig)
+ (cond
+ ((string-prefix? "helo" line)
+ (message-helo-set! msg (string-drop line (string-length "helo")))
+ (smtp-session 'ok)
+ (loop msg))
+ ((string-prefix? "ehlo" line)
+ (smtp-session 'ehlo (string-drop line (+ 1 (string-length "ehlo"))))
+ (loop msg))
+ ((string-prefix? "auth plain" line)
+ (let* ((auth-string (string-drop line-orig (+ 1 (string-length "auth plain"))))
+ (auth-decoded (base64-decode auth-string))
+ (auth-list (string-split auth-decoded "\x00"))
+ (user (car auth-list))
+ (password (cadr auth-list)))
+ (smtp-session 'set-user! user)
+ (smtp-session 'set-password! password)
+ (print "Attempted login, user: " user ", password: " password)
+ (smtp-session 'auth-success)
+ (loop msg)))
+ ((string-prefix? "mail from:" line)
+ (message-from-set! msg (string-drop line (string-length "mail from:")))
+ (smtp-session 'ok)
+ (loop msg))
+ ((string-prefix? "rcpt to:" line)
+ (message-to-set! msg (string-drop line (string-length "rcpt to:")))
+ (smtp-session 'ok)
+ (loop msg))
+ ((string-prefix? "data" line)
+ (smtp-session 'intermediate)
+ (let text-loop ((text-line (smtp-session 'get-line))
+ (text ""))
+ (if (string=? "." text-line)
+ (message-text-set! msg text)
+ (text-loop (smtp-session 'get-line)
+ (conc text text-line "\n"))))
+ (message-user-set! msg (smtp-session 'user))
+ (message-password-set! msg (smtp-session 'password))
+ (set! outbound-mail-queue (cons msg outbound-mail-queue))
+ (smtp-session 'ok)
+ (loop (make-empty-message)))
+ ((string-prefix? "quit" line)
+ (smtp-session 'close)
+ 'done)
+ ((string=? "" line)
+ (loop msg))
+ (else
+ (smtp-session 'not-implemented)
+ (loop msg))))
+ 'done))))
+
+
+;;; Message delivery
+;;
+
+(define (get-to-addresses config)
+ (map (lambda (p) (cons
+ (conc "<" (car p) "@" (config-host config) ">")
+ (cdr p)))
+ (map (lambda (file) (cons (pathname-file file) file))
+ (glob (conc (config-spool-dir config) "/*")))))
+
+(define (remove-angle-brackets addr)
+ (let ((left-idx (substring-index "<" addr))
+ (right-idx (substring-index ">" addr)))
+ (substring addr (+ left-idx 1) right-idx)))
+
+(define (deliver-message-local msg dest-dir)
+ (print "Delivering to maildir " dest-dir)
+ (with-output-to-file (conc dest-dir "/" (current-seconds))
+ (lambda ()
+ (print (message-text msg)))))
+
+(define (deliver-message msg config)
+ (let ((dest (assoc (message-to msg) (get-to-addresses config))))
+ (if dest
+ (let ((dest-file (cdr dest)))
+ (if (directory-exists? dest-file)
+ (deliver-message-local msg dest-file))
+ (print "Message DELIVERED:"))
+ (print "Message REJECTED:"))
+ (print " * From: " (message-from msg))
+ (print " * To: " (message-to msg)))
+ #t)
+
+
+;;; Command line argument parsing
+;;
+
+(define (print-usage progname)
+ (print "Usage:\n"
+ progname " -h/--help\n"
+ progname " [-u/--user UID] [-g/--group GID] hostname [[port [spooldir]]\n"
+ "\n"
+ "The -u and -g options can be used to set the UID and GID of the process\n"
+ "following the creation of the TCP port listener (which often requires root)."))
+
+(define (main)
+ (let ((progname (pathname-file (car (argv))))
+ (config (make-config "" 25 "/var/spool/mail" '() '())))
+ (if (null? (cdr (argv)))
+ (print-usage progname)
+ (let loop ((args (cdr (argv))))
+ (let ((this-arg (car args))
+ (rest-args (cdr args)))
+ (if (string-prefix? "-" this-arg)
+ (cond
+ ((or (equal? this-arg "-u")
+ (equal? this-arg "--user"))
+ (config-user-set! config (string->number (car rest-args)))
+ (loop (cdr rest-args)))
+ ((or (equal? this-arg "-g")
+ (equal? this-arg "--group"))
+ (config-group-set! config (string->number (car rest-args)))
+ (loop (cdr rest-args)))
+ ((or (equal? this-arg "-h")
+ (equal? this-arg "--help"))
+ (print-usage progname))
+ (else
+ (print "Unknown option " this-arg "\n")
+ (print-usage progname)))
+ (begin
+ (config-host-set! config this-arg)
+ (unless (null? rest-args)
+ (config-port-set! config (string->number (car rest-args)))
+ (unless (null? (cdr rest-args))
+ (config-spool-dir-set! config (cadr rest-args))))
+ (run-server config))))))))
+
+(main)
+
+;; (run-server (make-config "thelambdalab.xyz" 2525 "/var/spool/mail"))
The Lambda Lab / projects / lambdamail.git / blobdiff