diff options
| -rw-r--r-- | antispam.7 | 16 | ||||
| -rw-r--r-- | defconfig | 2 | ||||
| -rw-r--r-- | spool2dir.c | 268 |
3 files changed, 286 insertions, 0 deletions
@@ -94,6 +94,11 @@ into a spam folder and other mail regularly. Has the same drawbacks as the dspam-exec approach. +.SS spool2dir backend (general) + +This backend spools the message into a file. No further processing +is performed. You need to write an extra daemon that picks up the +spooled files and trains the spam filter as appropriate. .SH CONFIGURATION @@ -194,6 +199,17 @@ plugin { # NOTE: you need to set the signature for this backend antispam_signature = X-CRM114-CacheID + + #=================== + # spool2dir plugin + + # spam/not-spam spool2dir drop (default unset which will give errors) + # The first %%lu is replaced by the current time. + # The second %%lu is replaced by a counter to generate unique names. + # These two tokens MUST be present in the template! However + # you can insert any C-style modifier as shown. + # antispam_spool2dir_spam = /tmp/spamspool/%%020lu-%u-%%05lus + # antispam_spool2dir_notspam = /tmp/spamspool/%%020lu-%u-%%05luh } .fi @@ -14,10 +14,12 @@ # signature-log - signature logging using dovecot's dict API # mailtrain - send mail to special addresses for training # crm114-exec - direct crm114 training by calling mailreaver.crm +# spool2dir - spool trained emails to a directory #BACKEND=dspam-exec #BACKEND=signature-log #BACKEND=mailtrain #BACKEND=crm114-exec +#BACKEND=spool2dir # Dovecot build/header directory # Building the plugin requires configured dovecot sources or having diff --git a/spool2dir.c b/spool2dir.c new file mode 100644 index 0000000..06bd307 --- /dev/null +++ b/spool2dir.c @@ -0,0 +1,268 @@ +/* + * 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); + } else { + if (o_stream_send(outstream, beginning, 5) != 5) { + ret = -1; + mail_storage_set_error(t->box->storage, + ME(NOTPOSSIBLE) + "Failed to write line to temp"); + goto failed_to_copy; + } + } + + 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) +{ +} |