New action. Based on guimb/scm/vacation.scm and on ideas and code fragments from…

… Felix Egli <fegli at goldnet dot ch>.

+/* GNU Mailutils -- a suite of utilities for electronic mail
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+   This library 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 of the License, or (at your option) any later version.
+
+   This library 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 this library; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA  */
+
+/* Syntax: vacation [:days <ndays: number]
+                    [:subject <subject: string>]
+		    [:aliases <address-list: list>]
+		    [:addresses <noreply-address-list: list>]
+		    [:reply_regex <expr: string>]
+		    [:reply_prefix <prefix: string>]
+		    <reply text: string>
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <string.h>
+#include <signal.h>
+#include <regex.h>
+#ifdef USE_DBM
+# include <mu_dbm.h>
+#endif
+#include <mailutils/libsieve.h>
+#include <mailutils/mu_auth.h>
+
+/* Build a mime response message from original message MSG. TEXT
+   is the message text.
+   FIXME: This is for future use, when I add :mime tag
+*/
+static int
+build_mime (mime_t *pmime, message_t msg, const char *text)
+{
+  mime_t mime = NULL;
+  message_t newmsg;
+  stream_t stream;
+  size_t off = 0;
+  header_t hdr;
+  body_t body;
+  /* FIXME: charset */
+  char *header = "Content-Type: text/plain;charset=iso-8859-1\n"
+    "Content-Transfer-Encoding: 8bit\n\n";
+
+  mime_create (&mime, NULL, 0);
+
+  message_create (&newmsg, NULL);
+  message_get_body (newmsg, &body);
+  header_create (&hdr, header, strlen (header), newmsg);
+  message_set_header (newmsg, hdr, NULL);
+  body_get_stream (body, &stream);
+
+  stream_printf (stream, &off, "%s", text);
+  stream_close (stream);
+  mime_add_part (mime, newmsg);
+  message_unref (newmsg);
+
+  *pmime = mime;
+
+  return 0;
+}
+
+
+
+/* Produce diagnostic output. */
+static int
+diag (sieve_machine_t mach)
+{
+  if (sieve_get_debug_level (mach) & MU_SIEVE_DEBUG_TRACE)
+    {
+      sieve_locus_t locus;
+      sieve_get_locus (mach, &locus);
+      sieve_debug (mach, "%s:%lu: VACATION\n",
+		   locus.source_file,
+		   (unsigned long) locus.source_line);
+    }
+
+  sieve_log_action (mach, "VACATION", NULL);
+  return sieve_is_dry_run (mach);
+}
+
+
+struct addr_data {
+  address_t addr;
+  char *my_address;
+};
+
+static int
+_compare (void *item, void *data)
+{
+  struct addr_data *ad = data;
+  int rc = address_contains_email (ad->addr, item);
+  if (rc)
+    ad->my_address = item;
+  return rc;
+}
+
+/* Check whether an alias from ADDRESSES is part of To: or Cc: headers
+   of the originating mail. Return non-zero if so and store a pointer
+   to the matching address to *MY_ADDRESS. */
+static int
+match_addresses (header_t hdr, sieve_value_t *addresses, char **my_address)
+{
+  int match = 0;
+  char *str;
+  struct addr_data ad;
+
+  ad.my_address = NULL;
+  if (header_aget_value (hdr, MU_HEADER_TO, &str) == 0)
+    {
+      if (!address_create (&ad.addr, str))
+	{
+	  match += sieve_vlist_do (addresses, _compare, &ad);
+	  address_destroy (&ad.addr);
+	}
+      free (str);
+    }
+
+  if (!match && header_aget_value (hdr, MU_HEADER_CC, &str) == 0)
+    {
+      if (!address_create (&ad.addr, str))
+	{
+	  match += sieve_vlist_do (addresses, _compare, &ad);
+	  address_destroy (&ad.addr);
+	}
+      free (str);
+    }
+  *my_address = ad.my_address;
+  return match;
+}
+
+
+struct regex_data {
+  sieve_machine_t mach;
+  char *email;
+};
+
+static int
+regex_comparator (void *item, void *data)
+{
+  regex_t preg;
+  int rc;
+  struct regex_data *d = data;
+  
+  if (regcomp (&preg, item,
+	       REG_EXTENDED | REG_NOSUB | REG_NEWLINE | REG_ICASE))
+    {
+      sieve_error (d->mach,
+		   /* TRANSLATORS: 'vacation' is the name of a Sieve action.
+		      Do not translate it! */
+		       _
+		   ("%d: vacation - cannot compile regular expression \"%s\"\n"),
+		   sieve_get_message_num (d->mach),
+		   item);
+      return 0;
+    }
+  rc = regexec (&preg, d->email, 0, NULL, 0) == 0;
+  regfree (&preg);
+  return rc;
+}
+
+/* Decide whether EMAIL address should not be responded to.
+ */
+static int
+noreply_address_p (sieve_machine_t mach, list_t tags, char *email)
+{
+  int i, rc = 0;
+  sieve_value_t *arg;
+  struct regex_data rd;
+  static char *noreply_sender[] = {
+    ".*-REQUEST@.*",
+    ".*-RELAY@.*",
+    ".*-OWNER@.*",
+    "^OWNER-.*",
+    "^postmaster@.*",
+    "^UUCP@.*",
+    "^MAILER@.*",
+    "^MAILER-DAEMON@.*",
+    NULL
+  };
+
+  rd.mach = mach;
+  rd.email = email;
+  for (i = 0; rc == 0 && noreply_sender[i]; i++)
+    rc = regex_comparator (noreply_sender[i], &rd);
+
+  if (!rc && sieve_tag_lookup (tags, "addresses", &arg))
+    rc = sieve_vlist_do (arg, regex_comparator, &rd);
+  
+  return rc;
+}
+
+
+/* Return T if letter precedence is 'bulk' or 'junk' */
+static int
+bulk_precedence_p (header_t hdr)
+{
+  int rc = 0;
+  char *str;
+  if (header_aget_value (hdr, MU_HEADER_PRECEDENCE, &str) == 0)
+    {
+      rc = strcasecmp (str, "bulk") == 0
+	   || strcasecmp (str, "junk") == 0;
+      free (str);
+    }
+  return rc;
+}
+
+#define	DAYS_MIN	1
+#define	DAYS_DEFAULT	7
+#define	DAYS_MAX	60
+
+/* Check and updated vacation database. Return 0 if the mail should
+   be answered. */
+static int
+check_db (sieve_machine_t mach, list_t tags, char *from)
+{
+#ifdef USE_DBM
+  DBM_FILE db;
+  DBM_DATUM key, value;
+  time_t now;
+  char buffer[64];
+  char *file, *home;
+  sieve_value_t *arg;
+  unsigned int days;
+  int rc;
+  
+  if (sieve_tag_lookup (tags, "days", &arg))
+    {
+      days = arg->v.number;
+      if (days < DAYS_MIN)
+	days = DAYS_MIN;
+      else if (days > DAYS_MAX)
+	days = DAYS_MAX;
+    }
+  else
+    days = DAYS_DEFAULT;
+
+  home = mu_get_homedir ();
+
+  if (asprintf (&file, "%s/.vacation", (home ? home : ".")) == -1)
+    {
+      sieve_error (mach,
+		   /* TRANSLATORS: 'vacation' is the name of a Sieve action.
+		      Do not translate it! */
+		   _("%d: vacation - cannot build db filename\n"),
+		   sieve_get_message_num (mach));
+      free (home);
+      sieve_abort (mach);
+    }
+  free (home);
+  
+  rc = mu_dbm_open (file, &db, MU_STREAM_RDWR, 0600);
+  if (rc)
+    {
+      sieve_error (mach,
+		   /* TRANSLATORS: 'vacation' is the name of a Sieve action.
+		      Do not translate it! */
+		   _("%d: vacation - cannot open \"%s\": %s"),
+		   sieve_get_message_num (mach), file,
+		   mu_strerror (rc));
+      free (file);
+      sieve_abort (mach);
+    }
+  free (file);
+
+  time (&now);
+
+  MU_DATUM_SIZE (key) = strlen (from);
+  MU_DATUM_PTR (key) = from;
+
+  rc = mu_dbm_fetch (db, key, &value);
+  if (!rc)
+    {
+      time_t last;
+      
+      strncpy(buffer, MU_DATUM_PTR (value), MU_DATUM_SIZE (value));
+      buffer[MU_DATUM_SIZE (value)] = 0;
+
+      last = (time_t) strtoul (buffer, NULL, 0);
+
+
+      if (last + (24 * 60 * 60 * days) > now)
+	{
+	  mu_dbm_close (db);
+	  return 1;
+	}
+    }
+
+  MU_DATUM_SIZE (value) = snprintf (buffer, sizeof buffer, "%ld", now);
+  MU_DATUM_PTR (value) = buffer;
+  MU_DATUM_SIZE (key) = strlen (from);
+  MU_DATUM_PTR (key) = from;
+
+  mu_dbm_insert (db, key, value, 1);
+  mu_dbm_close (db);
+  return 0;
+#else
+  sieve_error (mach,
+	       /* TRANSLATORS: 'vacation' and ':days' are Sieve keywords.
+		  Do not translate them! */
+	       _("%d: vacation compiled without DBM support. Ignoring :days tag"),
+	       sieve_get_message_num (mach));
+  return 0;
+#endif
+}
+
+/* Add a reply prefix to the subject. *PSUBJECT points to the
+   original subject, which must be allocated using malloc. Before
+   returning its value is freed and replaced with the new one.
+   Default reply prefix is "Re: ", unless overridden by
+   "reply_prefix" tag.
+ */
+static void
+re_subject (sieve_machine_t mach, list_t tags, char **psubject)
+{
+  char *subject;
+  sieve_value_t *arg;
+  char *prefix = "Re";
+  
+  if (sieve_tag_lookup (tags, "reply_prefix", &arg))
+    {
+      prefix = arg->v.string;
+    }
+
+  subject = malloc (strlen (*psubject) + strlen (prefix) + 3);
+  if (!subject)
+    {
+      sieve_error (mach,
+		   ("%d: vacation - not enough memory"),
+		   sieve_get_message_num (mach));
+      return;
+    }
+  
+  strcpy (subject, prefix);
+  strcat (subject, ": ");
+  strcat (subject, *psubject);
+  free (*psubject);
+  *psubject = subject;
+}
+
+/* Process reply subject header.
+
+   If :subject is set, its value is used.
+   Otherwise, if original subject matches reply_regex, it is used verbatim.
+   Otherwise, reply_prefix is prepended to it. */
+
+static void
+vacation_subject (sieve_machine_t mach, list_t tags,
+		  message_t msg, header_t newhdr)
+{
+  sieve_value_t *arg;
+  char *value;
+  char *subject;
+  int subject_allocated;
+  header_t hdr;
+  
+  if (sieve_tag_lookup (tags, "subject", &arg))
+    {
+      subject =  arg->v.string;
+      subject_allocated = 0;
+    }
+  else if (message_get_header (msg, &hdr) == 0
+	   && header_aget_value_unfold (hdr, MU_HEADER_SUBJECT, &value) == 0)
+    {
+      char *p;
+      
+      int rc = rfc2047_decode ("iso-8859-1", value, &p);
+
+      subject_allocated = 1;
+      if (rc)
+	{
+	  subject = value;
+	  value = NULL;
+	}
+      else
+	{
+	  subject = p;
+	}
+
+      if (sieve_tag_lookup (tags, "reply_regex", &arg))
+	{
+	  char *err = NULL;
+	  
+	  rc = munre_set_regex (arg->v.string, 0, &err);
+	  if (rc)
+	    {
+	      sieve_error (mach,
+			   ("%d: vacation - cannot compile reply prefix regexp: %s: %s"),
+			   sieve_get_message_num (mach),
+			   mu_strerror (rc),
+			   err ? err : "");
+	    }
+	}
+	  
+      if (munre_subject (subject, NULL))
+	re_subject (mach, tags, &subject);
+      
+      free (value);
+    }
+
+  if (rfc2047_encode ("iso-8859-1", "quoted-printable",
+		      subject, &value))
+    header_set_value (newhdr, MU_HEADER_SUBJECT, subject, 0);
+  else
+    {
+      header_set_value (newhdr, MU_HEADER_SUBJECT, value, 0);
+      free (value);
+    }
+
+  if (subject_allocated)
+    free (subject);
+}
+
+/* Generate and send the reply message */
+static int
+vacation_reply (sieve_machine_t mach, list_t tags, message_t msg,
+		char *text, char *to, char *from)
+{
+  mime_t mime = NULL;
+  message_t newmsg;
+  header_t newhdr;
+  address_t to_addr = NULL, from_addr = NULL;
+  char *value;
+  mailer_t mailer;
+  int rc;
+  
+  build_mime (&mime, msg, text);
+  mime_get_message (mime, &newmsg);
+  message_get_header (newmsg, &newhdr);
+
+  rc = address_create (&to_addr, to);
+  if (rc)
+    {
+      sieve_error (mach,
+		   /* TRANSLATORS: 'vacation' is the name of a Sieve action.
+		      Do not translate it! */
+		   _
+		   ("%d: vacation - cannot create recipient address <%s>: %s\n"),
+		   sieve_get_message_num (mach), from, mu_strerror (rc));
+      return -1;
+    }
+
+  header_set_value (newhdr, MU_HEADER_TO, to, 0);
+  
+  vacation_subject (mach, tags, msg, newhdr);
+    
+  if (from)
+    {
+      if (address_create (&from_addr, from))
+	from_addr = NULL;
+    }
+  else
+    {
+      from_addr = NULL;
+    }
+  
+  mu_rfc2822_in_reply_to (msg, &value);
+  header_set_value (newhdr, MU_HEADER_IN_REPLY_TO, value, 1);
+  free (value);
+  
+  mu_rfc2822_references (msg, &value);
+  header_set_value (newhdr, MU_HEADER_REFERENCES, value, 1);
+  free (value);
+  
+  mailer = sieve_get_mailer (mach);
+  rc = mailer_open (mailer, 0);
+  if (rc)
+    {
+      url_t url = NULL;
+      mailer_get_url (mailer, &url);
+      
+      sieve_error (mach,
+		   /* TRANSLATORS: 'vacation' is the name of a Sieve action.
+		      Do not translate it! */
+		   _("%d: vacation - cannot open mailer %s: %s\n"),
+		   sieve_get_message_num (mach),
+		   url_to_string (url), mu_strerror (rc));
+      return -1;
+    }
+
+  rc = mailer_send_message (mailer, newmsg, from_addr, to_addr);
+  mailer_close (mailer);
+  return rc;
+}
+
+int
+sieve_action_vacation (sieve_machine_t mach, list_t args, list_t tags)
+{
+  int rc;
+  char *text, *from;
+  sieve_value_t *val;
+  message_t msg;
+  header_t hdr;
+  char *my_address = sieve_get_daemon_email (mach);
+  
+  if (diag (mach))
+    return 0;
+  
+  val = sieve_value_get (args, 0);
+  if (!val)
+    {
+      sieve_error (mach,
+		   /* TRANSLATORS: 'vacation' is the name of a Sieve action.
+		      Do not translate it! */
+		   _("vacation: cannot get text!"));
+      sieve_abort (mach);
+    }
+  else
+    text = val->v.string;
+
+  msg = sieve_get_message (mach);
+  message_get_header (msg, &hdr);
+
+  if (sieve_tag_lookup (tags, "sender", &val))
+    {
+      /* Debugging hook: :sender sets fake reply address */
+      from = strdup (val->v.string);
+    }
+  else if (sieve_get_message_sender (msg, &from))
+    {
+      sieve_error (mach,
+		   /* TRANSLATORS: 'vacation' is the name of a Sieve action.
+		      Do not translate it! */
+		   _("%d: vacation - cannot get sender address\n"),
+		   sieve_get_message_num (mach));
+      sieve_abort (mach);
+    }
+
+  if (sieve_tag_lookup (tags, "aliases", &val)
+      && match_addresses (hdr, val, &my_address) == 0)
+    return 0;
+
+  if (noreply_address_p (mach, tags, from)
+      || bulk_precedence_p (hdr)
+      || check_db (mach, tags, from))
+    {
+      free (from);
+      return 0;
+    }
+
+  rc = vacation_reply (mach, tags, msg, text, from, my_address);
+  free (from);
+  if (rc == -1)
+    sieve_abort (mach);
+  return rc;
+}
+
+/* Tagged arguments: */
+static sieve_tag_def_t vacation_tags[] = {
+  {"days", SVT_NUMBER},
+  {"subject", SVT_STRING},
+  {"aliases", SVT_STRING_LIST},
+  {"addresses", SVT_STRING_LIST},
+  {"reply_regex", SVT_STRING},
+  {"reply_prefix", SVT_STRING},
+  {NULL}
+};
+
+static sieve_tag_group_t vacation_tag_groups[] = {
+  {vacation_tags, NULL},
+  {NULL}
+};
+
+/* Required arguments: */
+static sieve_data_type vacation_args[] = {
+  SVT_STRING,			/* message text */
+  SVT_VOID
+};
+
+int SIEVE_EXPORT (vacation, init) (sieve_machine_t mach)
+{
+  return sieve_register_action (mach, "vacation", sieve_action_vacation,
+				vacation_args, vacation_tag_groups, 1);
+}