New file. Implements sieve extension test "timestamp".

+/* GNU Mailutils -- a suite of utilities for electronic mail
+   Copyright (C) 2003 Free Software Foundation, Inc.
+
+   GNU Mailutils is free software; you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   GNU Mailutils 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 Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with GNU Mailutils; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA  */
+
+/*  Syntax:   timestamp [":before"/":after"] <header-name: string>
+              <date: datestring>
+
+    The "timestamp" test compares the value of a structured date header
+    field with the given date.
+
+    If the tagged argument is ":after" and the date from the header is
+    after the specified date the result is true, otherwise, if the
+    header date is before the given date, the result is false.
+
+    If the tagged argument is ":before" and the date from the header is
+    before the specified date the result is true, otherwise, if the
+    header date is after the given date, the result is false.
+
+    If no tagged argument is supplied, :after is assumed.
+
+    Almost any date format is understood.
+
+    Example:  timestamp :before "X-Expire-Timestamp" "now - 5 days"
+
+    This test will return true, if the date in X-Expire-Timestamp is
+    more than 5 days older than the current date. */  
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif  
+
+#include <stdlib.h>
+#include <mailutils/libsieve.h>
+
+/* Handler for the timestamp test */
+static int
+timestamp_test (sieve_machine_t mach, list_t args, list_t tags)
+{
+  sieve_value_t *h, *v;
+  header_t hdr;
+  char *val;
+  time_t now = time (NULL);
+  time_t tlimit, tval;
+  int rc;
+  
+  if (sieve_get_debug_level (mach) & MU_SIEVE_DEBUG_TRACE)
+    sieve_debug (mach, "TIMESTAMP\n");
+
+  /* Retrieve required arguments: */
+  /* First argument: header name */
+  h = sieve_value_get (args, 0);
+  if (!h)
+    {
+      sieve_error (mach, "timestamp: can't get argument 1");
+      sieve_abort (mach);
+    }
+  /* Second argument: date displacement */
+  v = sieve_value_get (args, 1);
+  if (!v)
+    {
+      sieve_error (mach, "timestamp: can't get argument 2");
+      sieve_abort (mach);
+    }
+
+  if (mu_parse_date (v->v.string, &tlimit, &now))
+    {
+      sieve_error (mach, "timestamp: can't parse date specification (%s)",
+		   v->v.string);
+      sieve_abort (mach);
+    }
+
+  rc = message_get_header (sieve_get_message (mach), &hdr);
+  if (rc)
+    {
+      sieve_error (mach, "message_get_header: %s", mu_strerror (rc));
+      sieve_abort (mach);
+    }
+  
+  if (header_aget_value (hdr, h->v.string, &val))
+    return 0;
+
+  if (mu_parse_date (val, &tval, &now))
+    {
+      sieve_error (mach,
+		   "timestamp: can't parse header date specification (%s)",
+		   val);
+      free (val);
+      sieve_abort (mach);
+    }
+  free (val);
+
+  rc = tval > tlimit;
+    
+  if (sieve_tag_lookup (tags, "before", NULL))
+    rc = !rc;  
+
+  return rc;
+}
+
+/* Required arguments: */
+static sieve_data_type timestamp_req_args[] = {
+  SVT_STRING,
+  SVT_STRING,
+  SVT_VOID
+};
+
+/* Tagged arguments: */
+static sieve_tag_def_t timestamp_tags[] = {
+  { "after", SVT_VOID },
+  { "before", SVT_VOID },
+  { NULL }
+};
+
+static sieve_tag_group_t timestamp_tag_groups[] = {
+  { timestamp_tags, NULL },
+  { NULL }
+};
+
+/* Initialization function. It is the only function exported from this
+   module. */
+int
+SIEVE_EXPORT(timestamp,init) (sieve_machine_t mach)
+{
+  return sieve_register_test (mach, "timestamp", timestamp_test,
+                              timestamp_req_args, timestamp_tag_groups, 1);
+}