/*
* mailing backend for dovecot antispam plugin
*
* Copyright (C) 2008 Steffen Kaiser <skdovecot@smail.inf.fh-brs.de>
* this backend "spool2dir" bases on "mailtrain" backend of
* Copyright (C) 2007 Johannes Berg <johannes@sipsolutions.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License Version 2 as
* published by the Free Software Foundation.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
/*
* spool2dir antispam backend / plugin
*
* Any modification of SPAM status is recorded into a directory.
*
* Configuration
*
* Via settings similiar to the other antispam backends
* antispam_spool2dir_spam :- filename tempate for SPAM messages
* antispam_spool2dir_notsam :- filename tempate for HAM messages
*
* The templates _must_ provide two arguments:
* 1. %%lu - the current unix time (lowercase L, lowercase U)
* 2. %%lu - a counter to create different temporary files
* Note: The %-sign must be given two times to protect agains
* the expansion by Dovecot itself. You can put any legal
* format modification character of C's printf() function between
* '%%' and 'lu'.
*
* e.g.:
* antispam_spool2dir_spam = /tmp/spamspool/%%020lu-%%05lu-%u-S
* antispam_spool2dir_ham = /tmp/spamspool/%%020lu-%%05lu-%u-H
*
* This example will spool the messages into the directory
* /tmp/spamspool. The individual files start with 20 digits,
* followe by a dash, 5 digits, the current username and S or H,
* indicating Spam or Ham messages.
* The first %%lu placeholder is replace by the current unix time,
* the second %%lu with the counter. That way, if the same user
* trains the same message twice, the filename indicates the order
* in which it was done. So if the message was trained as SPAM first,
* as HAM later, HAM superceeds SPAM.
*
* Operation
*
* When the antispam plugin identifies detects a SPAM status change,
* e.g. moving/copying a message from any antispam_spam folder into
* a folder _not_ listed in antispam_spam or antispam_trash, this
* backend spools the complete message into antispam_mail_basedir.
* If there is an error copying _all_ messages around, old spools
* are kept, but the current one is deleted. For instance, if the
* user is copying 15 messages, but only 10 succeed, the 10 would
* be usually deleted. In this backend there is no rollback of
* successfully spooled message, only the failed message is
* deleted.
*
* Possible usage models
*
* A)
* I use spool2dir for training the Bayes database as follows:
*
* Every 10 seconds a service invokes the training program, unless
* it already runs.
*
* The training progran reads the content of the spool directory, sorts
* the filenames alphanumerically, waits two seconds to allow any current
* spool2dir processes to finish currently open files.
* Then one message at a time is read and identified, if it contains
* local modifications, e.g. user-visible SPAM reports, which are removed.
* Furthermore, reports of untrustworthy people are discarded.
* This process continues until either all messages are processed or
* the next message would have another SPAM report type (HAM or SPAM). The
* file names of the messages processed til now are passed to the Bayes
* trainer to be processed within one run. Then those messages are removed.
*
* B)
*
* An Inotify server watches the spamspool directory and passes the messages
* to spamd. No need for the filenames to indicate the order anymore, unless
* the inotify server is not fast enough.
*/
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include "lib.h"
#include "mail-storage-private.h"
#include "ostream.h"
#include "istream.h"
#include "antispam-plugin.h"
static const char *spamspool = NULL;
static const char * hamspool = NULL;
struct antispam_transaction_context {
int count;
};
void backend_rollback(struct antispam_transaction_context *ast)
{
i_free(ast);
}
int backend_commit(struct mailbox_transaction_context *ctx __attr_unused__,
struct antispam_transaction_context *ast)
{
i_free(ast);
return 0;
}
int backend_handle_mail(struct mailbox_transaction_context *t,
struct antispam_transaction_context *ast,
struct mail *mail, enum classification wanted)
{
struct istream *mailstream;
struct ostream *outstream;
int ret;
const char *dest, *buf;
const unsigned char *beginning;
size_t size;
int fd;
i_assert(ast);
switch (wanted) {
case CLASS_SPAM:
dest = spamspool;
break;
case CLASS_NOTSPAM:
dest = hamspool;
break;
default: /* cannot handle this */
return -1;
}
if(!dest) {
mail_storage_set_error(t->box->storage,
ME(NOTPOSSIBLE)
"antispam plugin / spool2dir backend not configured");
return -1;
}
mailstream = get_mail_stream(mail);
if (!mailstream) {
mail_storage_set_error(t->box->storage,
ME(EXPUNGED)
"Failed to get mail contents");
return -1;
}
t_push();
/* atomically create a _new_ file */
while (ast->count <= 9999) {
buf = t_strdup_printf(dest, (long)time(0), (long)++ast->count);
fd = open(buf, O_CREAT | O_EXCL | O_WRONLY, 0600);
if(fd >= 0 || errno != EEXIST)
break;
/* current filename in buf already exists, zap it */
t_pop();
t_push();
/* buf is invalid now ! */
}
if (fd < 0) {
debug("spool2dir backend: Failed to create spool file %s: %s\n",
dest, strerror(errno));
mail_storage_set_error(t->box->storage,
ME(NOTPOSSIBLE)
"Failed to create spool file");
goto out;
}
/* buf still points to allocated memory, because fd >= 0 */
outstream = o_stream_create_from_fd(fd, t->box->pool);
if (!outstream) {
mail_storage_set_error(t->box->storage,
ME(NOTPOSSIBLE)
"Failed to stream spool file");
goto out_close;
}
if (i_stream_read_data(mailstream, &beginning, &size, 5) < 0 ||
size < 5) {
ret = -1;
mail_storage_set_error(t->box->storage,
ME(NOTPOSSIBLE)
"Failed to read mail beginning");
goto failed_to_copy;
}
/* "From "? skip line */
if (memcmp("From ", beginning, 5) == 0)
i_stream_read_next_line(mailstream);
if (o_stream_send_istream(outstream, mailstream) < 0) {
ret = -1;
mail_storage_set_error(t->box->storage,
ME(NOTPOSSIBLE)
"Failed to copy to spool file");
goto failed_to_copy;
}
ret = 0;
failed_to_copy:
o_stream_destroy(&outstream);
out_close:
close(fd);
out:
if (ret)
unlink(buf);
t_pop();
return ret;
}
void backend_init(pool_t pool __attr_unused__)
{
if((spamspool = get_setting("SPOOL2DIR_SPAM")))
debug("spool2dir spamspool %s\n", spamspool);
if((hamspool = get_setting("SPOOL2DIR_NOTSPAM")))
debug("spool2dir hamspool %s\n", hamspool);
}
struct antispam_transaction_context *
backend_start(struct mailbox *box __attr_unused__)
{
struct antispam_transaction_context *ast;
ast = i_new(struct antispam_transaction_context, 1);
ast->count = 0;
return ast;
}
void backend_exit(void)
{
}
