X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=lambdamail.git;a=blobdiff_plain;f=lambdamail.scm;h=a2fd01d5f1bc95dedae12f1bab762987adc0372b;hp=48383e4c345ca16251106012cf7867b17d3b2dcc;hb=d65171f4b3d1734ee7d13884cdb9da9ba99a3f7c;hpb=eddd9a3e568bfc834ff297d129ef74162be37e23

diff --git a/lambdamail.scm b/lambdamail.scm
index 48383e4..a2fd01d 100644
--- a/lambdamail.scm
+++ b/lambdamail.scm
@@ -14,14 +14,18 @@
         (chicken process-context)
         (chicken process-context posix)
         (chicken condition)
+        (chicken sort)
         srfi-1 srfi-13 matchable base64)
 
-(define lambdamail-version "LambdaMail v0.0.1")
+(define lambdamail-version "LambdaMail v1.5.0")
 
 (define-record config host port spool-dir user group)
 (define-record message to from text user password)
 (define (make-empty-message) (make-message "" "" "" "" ""))
 
+(define (time-stamp)
+  (time->string (seconds->local-time) "%d %b %Y %T %z"))
+
 
 ;;; Server initialization
 ;;
@@ -58,9 +62,10 @@
 
 (define (receive-messages listener config)
   (let ((messages '()))
+    (print "*** Waiting for incoming mail")
     (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)))
+        (print "Accepted connection from " remote-ip " on " (time-stamp)))
       (condition-case
           (set! messages (process-smtp (make-smtp-session in-port out-port config) config))
         (o (exn)
@@ -71,16 +76,13 @@
     messages))
 
 (define (make-smtp-session in-port out-port config)
-  (let ((user "")
-        (password ""))
-    (lambda msg
-      (match msg
+  (let ((helo ""))
+    (lambda command
+      (match command
         (('get-line) (read-line in-port))
-        (('send-line strings ...) (write-line (conc (apply conc strings) "\r") out-port))
-        (('set-user! u) (set! user u))
-        (('set-password! p) (set! password p))
-        (('user) user)
-        (('password) password)))))
+        (('send strings ...) (write-line (conc (apply conc strings) "\r") out-port))
+        (('set-helo! h) (set! helo h))
+        (('helo) helo)))))
 
 (define (smtp-command? cmd-string input-string)
   (string-prefix? cmd-string (string-downcase input-string)))
@@ -91,99 +93,72 @@
       ""))
 
 (define (process-smtp smtp-session config)
-  (smtp-session 'send-line "220 " (config-host config) lambdamail-version)
+  (smtp-session 'send "220 " (config-host config) " " lambdamail-version)
   (let loop ((msg (make-empty-message))
              (received-messages '()))
     (let ((line (smtp-session 'get-line)))
-      (when (string? line)
-        (print "got " line)
-        (cond
-         ((smtp-command? "helo" line)
-          (smtp-session 'send-line "250 ok")
-          (loop msg received-messages))
-         ((smtp-command? "ehlo" line)
-          (smtp-session 'send-line
-                        "250-" (config-host config)
-                        " Hello " (smtp-command-args "ehlo" line))
-          (smtp-session 'send-line "250 AUTH PLAIN")
-          ;; (smtp-session 'send-line "250 STARTTLS")
-          (loop msg received-messages))
-         ((smtp-command? "auth plain" line)
-          (let* ((auth-string (smtp-command-args "auth plain" line))
-                 (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 'send-line "235 authentication successful")
-            (loop msg received-messages)))
-         ((smtp-command? "mail from:" line)
-          (message-from-set! msg (smtp-command-args "mail from:" line))
-          (smtp-session 'send-line "250 ok")
-          (loop msg received-messages))
-         ((smtp-command? "rcpt to:" line)
-          (message-to-set! msg (smtp-command-args "rcpt to:" line))
-          (smtp-session 'send-line "250 ok")
-          (loop msg received-messages))
-         ((smtp-command? "data" line)
-          (smtp-session 'send-line "354 intermediate")
-          (let text-loop ((text ""))
-            (let ((text-line (smtp-session 'get-line)))
-              (if (string=? "." text-line)
-                  (message-text-set! msg text)
-                  (text-loop (conc text text-line "\n")))))
-          (message-user-set! msg (smtp-session 'user))
-          (message-password-set! msg (smtp-session 'password))
-          (smtp-session 'send-line "250 ok")
-          (loop (make-empty-message) (cons msg received-messages)))
-         ((smtp-command? "quit" line)
-          (smtp-session 'send-line "221 closing transmission channel")
-          received-messages)
-         ((string=? "" (string-trim line))
-          (loop msg received-messages))
-         (else
-          (smtp-session 'send-line "502 command not implemented")
-          (loop msg received-messages)))))))
-
-
-;;; Sending/Delivering messages
+      (print "got " line)
+      (if (not (string? line))
+          '() ; Don't keep anything on unexpected termination.
+          (cond
+           ((smtp-command? "helo" line)
+            (smtp-session 'set-helo! (smtp-command-args "helo" line))
+            (smtp-session 'send "250 ok")
+            (loop msg received-messages))
+           ((smtp-command? "ehlo" line)
+            (smtp-session 'set-helo! (smtp-command-args "helo" line))
+            (smtp-session 'send
+                          "250-" (config-host config)
+                          " Hello " (smtp-command-args "ehlo" line))
+            (smtp-session 'send "250 AUTH PLAIN")
+            ;; (smtp-session 'send "250 STARTTLS")
+            (loop msg received-messages))
+           ((smtp-command? "auth plain" line)
+            (let* ((auth-string (smtp-command-args "auth plain" line))
+                   (auth-decoded (base64-decode auth-string))
+                   (auth-list (string-split auth-decoded "\x00"))
+                   (user (car auth-list))
+                   (password (cadr auth-list)))
+              (message-user-set! msg user)
+              (message-password-set! msg password)
+              (print "Attempted login, user: " user ", password: " password)
+              (smtp-session 'send "235 authentication successful")
+              (loop msg received-messages)))
+           ((smtp-command? "mail from:" line)
+            (message-from-set! msg (smtp-command-args "mail from:" line))
+            (smtp-session 'send "250 ok")
+            (loop msg received-messages))
+           ((smtp-command? "rcpt to:" line)
+            (message-to-set! msg (smtp-command-args "rcpt to:" line))
+            (if (message-valid? msg config)
+                (smtp-session 'send "250 ok")
+                (smtp-session 'send "551 relay forbidden"))
+            (loop msg received-messages))
+           ((smtp-command? "data" line)
+            (smtp-session 'send "354 intermediate")
+            (let text-loop ((text (conc "Received: from " (smtp-session 'helo) "\n"
+                                        "\tby " (config-host config) "\n"
+                                        "\tfor " (message-to msg) ";\n"
+                                        "\t" (time-stamp) "\n")))
+              (let ((text-line (smtp-session 'get-line)))
+                (if (string=? "." text-line)
+                    (message-text-set! msg text)
+                    (text-loop (conc text text-line "\n")))))
+            (smtp-session 'send "250 ok")
+            (loop (make-empty-message) (cons msg received-messages)))
+           ((smtp-command? "quit" line)
+            (smtp-session 'send "221 closing transmission channel")
+            received-messages)
+           ((string=? "" (string-trim line))
+            (loop msg received-messages))
+           (else
+            (smtp-session 'send "502 command not implemented")
+            (loop msg received-messages)))))))
+
+
+;;; Message stamping and validation
 ;;
 
-(define (deliver-messages config messages)
-  (print "Attempting delivery of " (length messages) " mail items.")
-  (filter (lambda (msg) (not (deliver-message msg config)))
-          messages))
-
-(define (deliver-message msg config)
-  (let* ((local-addresses (get-local-addresses config))
-         (dest (assoc (message-to msg) local-addresses))
-         (orig (assoc (message-from msg) local-addresses)))
-    (cond
-     (dest
-      (let ((dest-dir (cadr dest)))
-        (deliver-message-local msg dest-file))
-      (print "Message DELIVERED (local):"))
-     (orig
-      (let ((password (caddr orig)))
-        (if (and
-             (string=? (conc "<" (message-user msg) "@" (config-host config) ">")
-                       (message-from msg))
-             password
-             (string=? (message-password msg) password))
-            (begin
-              (deliver-message-remote msg)
-              (print "Message DELIVERED (remote):"))
-            (print "Message DELIVERY REJECTED (auth failure):"))))
-     (else
-      (print "Message DELIVERY REJECTED (relay forbidden):"))))
-  (print " * From: " (message-from msg))
-  (print " * To: " (message-to msg))
-  #t)
-
-;; Local delivery
-
 (define (get-local-addresses config)
   (map (lambda (p) (cons
                     (conc "<" (car p) "@" (config-host config) ">")
@@ -197,16 +172,140 @@
             (filter directory-exists?
                     (glob (conc (config-spool-dir config) "/*"))))))
 
+(define (message-stamp msg config)
+  (let* ((local-addresses (get-local-addresses config))
+         (local-dest (assoc (message-to msg) local-addresses))
+         (local-src (assoc (message-from msg) local-addresses)))
+    (cond
+     (local-dest
+      (list #t 'local (cadr local-dest)))
+     (local-src
+      (let ((password (caddr local-src)))
+        (if (and (string=? (conc "<" (message-user msg) "@" (config-host config) ">")
+                           (message-from msg))
+                 password
+                 (string=? (message-password msg) password))
+            (list #t 'remote)
+            (begin
+              (print "Provided password " (message-password msg))
+              (print "Host password " password)
+              (list #f 'remote)))))
+     (else
+      (list #f 'relay)))))
+
+(define (message-valid? msg config)
+  (let ((stamp (message-stamp msg config)))
+    (print "Stamp: " stamp)
+    (car stamp)))
+
+
+;;; Sending/Delivering messages
+;;
+
+(define (deliver-messages config messages)
+  (print "*** Attempting delivery of " (length messages) " mail items.")
+  (filter (lambda (msg) (not (deliver-message msg config)))
+          messages))
+
+(define (deliver-message msg config)
+  (print "From: " (message-from msg))
+  (print "To: " (message-to msg))
+  (condition-case
+    (match (message-stamp msg config)
+      ((#t 'local dest-dir) (deliver-message-local msg dest-dir))
+      ((#t 'remote) (deliver-message-remote msg config))
+      ((#f 'remote)
+       (print "* REMOTE DELIVERY NOT ALLOWED (auth failure)")
+       #t)
+      (else
+       (print "* DELIVERY NOT ALLOWED (relay forbidden)")
+       #t))
+    (o (exn)
+       (print "* DELIVERY FAILED")
+       (print-error-message o)
+       #t)))
+
+;; Local delivery
+
 (define (deliver-message-local msg dest-dir)
   (with-output-to-file (conc dest-dir "/" (current-seconds))
     (lambda ()
-      (print (message-text msg)))))
+      (print (message-text msg))))
+  (print "* MESSAGE DELIVERED (local)")
+  #t)
 
 
 ;; Remote delivery
 
-(define (deliver-message-remote msg)
-  (print "TODO"))
+(define (get-domain-from-email email-string)
+  (car (string-split (cadr (string-split email-string "@")) ">")))
+
+;; This is a hack - there's no built-in interface to res_query()
+;; in chicken, so we have to resort to a system call to dig...
+(define (get-mail-server-for-domain domain)
+  (let* ((mx-lines (let-values (((in out id) (process (conc "dig " domain " mx +short"))))
+                     (with-input-from-port in read-lines)))
+         (mx-entries (map (lambda (l)
+                            (let ((s (string-split l)))
+                              (list (string->number (car s)) 
+                                    (string-drop-right (cadr s) 1)))) ; remove trailing "."
+                          mx-lines))
+         (sorted-mx-entries (sort mx-entries (lambda (e f) (< (car e) (car f))))))
+    (if (null? sorted-mx-entries)
+        domain ; fall-back to email address domain if no mx entries
+        (cadar sorted-mx-entries)))) ; otherwise pick the highest priority server
+
+(define (deliver-message-remote msg config)
+  (let* ((domain (get-domain-from-email (message-to msg)))
+         (mail-server (get-mail-server-for-domain domain)))
+    (print "Attempting delivery to " mail-server)
+    (let-values (((tcp-in tcp-out) (tcp-connect mail-server 25)))
+      (let ((smtp-session (make-outgoing-smtp-session tcp-in tcp-out)))
+        (let ((result (and
+                       (smtp-session 'expect "220")
+                       (smtp-session 'send "helo " (config-host config))
+                       (smtp-session 'expect "250")
+                       (smtp-session 'send "mail from:" (message-from msg))
+                       (smtp-session 'expect "250")
+                       (smtp-session 'send "rcpt to:" (message-to msg))
+                       (smtp-session 'expect "250")
+                       (smtp-session 'send "data")
+                       (smtp-session 'expect "354")
+                       (smtp-session 'send (message-text msg))
+                       (smtp-session 'send ".")
+                       (smtp-session 'expect "250" "5") ;Do not try again on rejects.
+                       (smtp-session 'send "quit"))))
+          (close-input-port tcp-in)
+          (close-output-port tcp-out)
+          (print "Connection closed.")
+          (if result
+              (print "* MESSAGE DELIVERED (remote)")
+              (print "* REMOTE DELIVERY FAILED (unexpected server response)"))
+          result)))))
+
+(define (or-list l)
+  (fold (lambda (a b) (or a b)) #f l))
+
+(define ((make-outgoing-smtp-session tcp-in tcp-out) . command)
+  (match command
+    (('expect codes ...)
+     (let loop ((result (read-line tcp-in)))
+       (if (and (> (string-length result) 3)
+                (eq? (string-ref result 3) #\-))
+           (loop (read-line tcp-in)) ;status continues on next line
+           (begin
+             (print "Expecting one of " codes " got " result)
+             (or-list (map (lambda (code)
+                             (string-prefix? code result))
+                           codes))))))
+    (('send strings ...)
+     (print "Sending " (if (> (string-length (car strings)) 30)
+                           (string-take (car strings) 30)
+                           (car strings)))
+     (let ((processed-string
+            (string-translate* (conc (apply conc strings) "\n")
+                               '(("\n" . "\r\n")))))
+       (write-string processed-string #f tcp-out)))))
 
 
 ;;; Command line argument parsing
@@ -215,11 +314,15 @@
 (define (print-usage progname)
   (print "Usage:\n"
          progname " -h/--help\n"
+         progname " -v/--version\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 (print-version)
+  (print lambdamail-version))
+
 (define (main)
   (let ((progname (pathname-file (car (argv))))
         (config (make-config "" 25 "/var/spool/mail" '() '())))
@@ -241,6 +344,9 @@
                  ((or (equal? this-arg "-h")
                       (equal? this-arg "--help"))
                   (print-usage progname))
+                 ((or (equal? this-arg "-v")
+                      (equal? this-arg "--version"))
+                  (print-version))
                  (else
                   (print "Unknown option " this-arg "\n")
                   (print-usage progname)))
@@ -256,3 +362,5 @@
 
 ;; (define (test)
 ;;   (run-server (make-config "localhost" 2525 "spool" '() '())))
+
+;; (test)