path: root/dspam-exec.c

/*
 * dspam backend for dovecot antispam plugin
 *
 * Copyright (C) 2004-2007  Johannes Berg <johannes@sipsolutions.net>
 *                    2006  Frank Cusack
 *
 * 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
 */

#include <stdlib.h>
#include <sys/wait.h>
#include <fcntl.h>

#include "lib.h"

#include "plugin.h"
#include "api-compat.h"

static const char *dspam_binary = "/usr/bin/dspam";
static char **extra_args = NULL;
static int extra_args_num = 0;

#define FIXED_ARGS_NUM 6

static int call_dspam(pool_t pool, const char *signature, bool is_spam)
{
	pid_t pid;
	const char *class_arg;
	const char *sign_arg;
	int pipes[2];

	sign_arg = t_strconcat("--signature=", signature, NULL);
	if (is_spam)
		class_arg = t_strconcat("--class=", "spam", NULL);
	else
		class_arg = t_strconcat("--class=", "innocent", NULL);

	/*
	 * For dspam stderr; dspam seems to not always exit with a
	 * non-zero exit code on errors so we treat it as an error
	 * if it logged anything to stderr.
	 */
	pipe(pipes);

	pid = fork();
	if (pid < 0)
		return -1;

	if (pid) {
		int status;
		char buf[1024];
		int readsize;
		bool error = FALSE;

		close(pipes[1]);

		do {
			readsize = read(pipes[0], buf, sizeof(buf));
			if (readsize < 0) {
				readsize = -1;
				if (errno == EINTR)
					readsize = -2;
			}

			/*
			 * readsize > 0 means that we read a message from
			 * dspam, -1 means we failed to read for some odd
			 * reason
			 */
			if (readsize > 0 || readsize == -1)
				error = TRUE;
		} while (readsize == -2 || readsize > 0);

		/*
		 * Wait for dspam, should return instantly since we've
		 * already waited above (waiting for stderr to close)
		 */
		waitpid(pid, &status, 0);
		if (!WIFEXITED(status))
			error = TRUE;

		close(pipes[0]);
		if (error)
			return 1;
		return WEXITSTATUS(status);
	} else {
		int fd = open("/dev/null", O_RDONLY);
		char **argv;
		int sz = sizeof(char *) * (FIXED_ARGS_NUM + extra_args_num);
		int i;

		argv = p_malloc(pool, sz);
		memset(argv, 0, sz);

		close(0);
		close(1);
		close(2);
		/* see above */
		close(pipes[0]);

		if (dup2(pipes[1], 2) != 2)
			exit(1);
		if (dup2(pipes[1], 1) != 1)
			exit(1);
		close(pipes[1]);

		if (dup2(fd, 0) != 0)
			exit(1);
		close(fd);

		argv[0] = (char *)dspam_binary;
		argv[1] = "--source=error";
		argv[2] = "--stdout";
		argv[3] = (char *)class_arg;
		argv[4] = (char *)sign_arg;

		debug("antispam: %s --source=error --stdout %s %s ...",
		      dspam_binary, class_arg, sign_arg);

		for (i = 0; i < extra_args_num; i++)
			argv[i + 5] = (char *)extra_args[i];

		execv(dspam_binary, argv);
		/* fall through if dspam can't be found */
		exit(127);
		/* not reached */
		return -1;
	}
}

bool backend(pool_t pool, bool spam, struct strlist *sigs)
{
	int ret;

	/* got all signatures now, walk them passing to dspam */
	while (sigs) {
		ret = call_dspam(pool, sigs->str, spam);
		if (ret)
			return FALSE;
		sigs = sigs->next;
	}

	return TRUE;
}

void backend_init(pool_t pool)
{
	char *tmp;
	int i;

	tmp = getenv("ANTISPAM_DSPAM_BINARY");
	if (tmp) {
		dspam_binary = tmp;
		debug("dspam binary set to %s\n", tmp);
	}

	tmp = getenv("ANTISPAM_DSPAM_ARGS");
	if (tmp) {
		extra_args = p_strsplit(pool, tmp, ";");
		extra_args_num = str_array_length(
					(const char *const *)extra_args);
		for (i = 0; i < extra_args_num; i++)
			debug("antispam: dspam extra arg %s\n",
			      extra_args[i]);
	}
}

void backend_exit(void)
{
}