X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=lambdamail.git;a=blobdiff_plain;f=lambdamail.scm;h=c3a68c1a2f37c97711015f4818a06ab64e3a7ede;hp=ddbce660e681400cc4cfdc8e620abc043dd84e6a;hb=716c2b0f7ffa6e8b0821d3b293a20154fd9e3f3a;hpb=a9ace437760a15f9a6233cdfbe1fb2d1d42145eb

diff --git a/lambdamail.scm b/lambdamail.scm
index ddbce66..c3a68c1 100644
--- a/lambdamail.scm
+++ b/lambdamail.scm
@@ -14,9 +14,10 @@
         (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 v1.2.0")
 
 (define-record config host port spool-dir user group)
 (define-record message to from text user password)
@@ -61,6 +62,7 @@
 
 (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 " (time-stamp)))
@@ -97,107 +99,106 @@
       ""))
 
 (define (process-smtp smtp-session config)
-  (smtp-session 'send "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 '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)))
-            (smtp-session 'set-user! user)
-            (smtp-session 'set-password! 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))
-          (smtp-session 'send "250 ok")
-          (loop msg received-messages))
-         ((smtp-command? "data" line)
-          (smtp-session 'send "354 intermediate")
-          (let text-loop ((text (conc "Received: from " (smtp-session 'helo) "\n"
-                                      "   by " (config-host config) "\n"
-                                      "   for " (message-from msg)
-                                      "; " (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")))))
-          (message-user-set! msg (smtp-session 'user))
-          (message-password-set! msg (smtp-session 'password))
-          (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)))))))
+      (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)))
+              (smtp-session 'set-user! user)
+              (smtp-session 'set-password! 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))
+            (smtp-session 'send "250 ok")
+            (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")))))
+            (message-user-set! msg (smtp-session 'user))
+            (message-password-set! msg (smtp-session 'password))
+            (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)))))))
 
 
 ;;; Sending/Delivering messages
 ;;
 
 (define (deliver-messages config messages)
-  (print "\n"
-         "**** Attempting delivery of " (length messages) " mail items.")
+  (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
-      (begin
-        (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 config)
-                    (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)
+      (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-dir)))
+         (orig
+          (let ((password (caddr orig)))
+            (if (and (string=? (conc "<" (message-user msg) "@" (config-host config) ">")
+                               (message-from msg))
+                     password
+                     (string=? (message-password msg) password))
+                (deliver-message-remote msg config)
+                (begin
+                  (print "* REMOTE DELIVERY NOT ALLOWED (auth failure)")
+                  #t))))
+         (else
+          (print "* REMOTE DELIVERY REJECTED (relay forbidden)")
+          #t)))
     (o (exn)
-       (print "Message delivery failed.")
-       (print-error-message o))))
+       (print "* DELIVERY FAILED")
+       (print-error-message o)
+       #t)))
+
 
 ;; Local delivery
 
@@ -217,18 +218,36 @@
 (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 (get-host-from-email email-string)
+(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 ((host (get-host-from-email (message-to msg))))
-    (print "Attempting delivery to host " host)
-    (let-values (((tcp-in tcp-out) (tcp-connect host 25)))
+  (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")
@@ -242,18 +261,25 @@
                        (smtp-session 'expect "354")
                        (smtp-session 'send (message-text msg))
                        (smtp-session 'send ".")
-                       (smtp-session 'expect "250")
+                       (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 code)
+    (('expect codes ...)
      (let ((result (read-line tcp-in)))
-       (print "Expecting " code " got " result)
-       (string-prefix? code result)))
+       (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)
@@ -263,17 +289,22 @@
                                '(("\n" . "\r\n")))))
        (write-string processed-string #f tcp-out)))))
 
+
 ;;; Command line argument parsing
 ;;
 
 (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" '() '())))
@@ -295,6 +326,9 @@
                  ((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)))
@@ -309,4 +343,4 @@
 (main)
 
 ;; (define (test)
-;;   (run-server (make-config "localhost" 2525 "spool" '() '())))
+  ;; (run-server (make-config "localhost" 2525 "spool" '() '())))