(expire_mark_message): New function

@@ -20,12 +20,19 @@
 /* EXPIRE see RFC2449:
 
   Implementation:
-    When a message is downloaded it is mark, pop3d_mark_retr(attr) 
-    at the update state the expire date is set on a header field
-     asprintf (.. "X-Expire-Timestamp: %ld", (long)time(NULL));
-    The message is not actually remove, we rely on external
-    program to do it.
- */
+    When a message is downloaded by RETR, it is marked with
+    "X-Expire-Timestamp: N", where N is the current value of
+    UNIX timestamp.
+
+    If pop3d was started with --delete-expired, the messages whose
+    X-Expire-Timestamp is more than (time(NULL)-expire days) old
+    are deleted.
+
+    Otherwise, such messages remain in the mailbox and the system
+    administrator is supposed to run a cron job that purges the mailboxes
+    (easily done using GNU sieve timestamp extension).
+
+*/
 
 void
 pop3d_mark_retr (attribute_t attr)
@@ -45,3 +52,54 @@ pop3d_unmark_retr (attribute_t attr)
   if (attribute_is_userflag (attr, POP3_ATTRIBUTE_RETR))
     attribute_unset_userflag (attr, POP3_ATTRIBUTE_RETR);
 }
+
+static int
+header_is_expired (header_t hdr)
+{
+  time_t timestamp;
+  char buf[64];
+  char *p;
+  
+  if (!expire_on_exit)
+    return 0;
+  if (header_get_value (hdr, MU_HEADER_X_EXPIRE_TIMESTAMP,
+			buf, sizeof buf, NULL))
+    return 0;
+  timestamp = strtoul (buf, &p, 0);
+  while (*p && isspace (*p))
+    p++;
+  if (*p)
+    return 0;
+  return time (NULL) >= timestamp + expire * 86400;
+}
+
+/* If pop3d is started with --expire, add an expiration header to the message.
+   Additionally, if --deltete-expired option was given, mark
+   the message as deleted if its X-Expire-Timestamp is too old.
+   Arguments:
+      msg   - Message to operate upon
+      value - Points to a character buffer where the value of
+              X-Expire-Timestamp is to be stored. *value must be set to
+	      NULL upon the first invocation of this function */
+void
+expire_mark_message (message_t msg, char **value)
+{
+  /* Mark the message with a timestamp. */
+  if (expire != EXPIRE_NEVER)
+    {
+      header_t header = NULL;
+      attribute_t attr = NULL;
+      
+      if (!*value)
+	asprintf (value, "%lu", (unsigned long) time (NULL));
+      
+      message_get_header (msg, &header);
+      message_get_attribute (msg, &attr);
+	  
+      if (pop3d_is_retr (attr))
+	header_set_value (header, MU_HEADER_X_EXPIRE_TIMESTAMP, *value, 0);
+      
+      if (header_is_expired (header))
+	attribute_set_deleted (attr);
+    }
+}