/*

 * Copyright (c) 2014 Sunil Nimmagadda <sunil@nimmagadda.net>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

#include <sys/param.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/time.h>

#include <sys/wait.h>

#include <bsd_auth.h>

#include <err.h>

#include <event.h>

#include <login_cap.h>

#include <pwd.h>

#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <syslog.h>

#include <unistd.h>

#include "imsgev.h"

#include "pop3d.h"

#define	MBOX_PATH	"/var/mail/%u"

#define MAILDIR_PATH	"~/Maildir"

#define	POP3D_USER	"_pop3d"

#define CERTFILE	"/etc/ssl/server.crt"

#define KEYFILE		"/etc/ssl/private/server.key"

static void authenticate(struct imsgev *, struct imsg *);

static void pop3e_imsgev(struct imsgev *, int , struct imsg *);

static void needfd(struct imsgev *);

static void sig_handler(int, short, void *);

static enum m_type m_type(const char *);

static void usage(void);

static struct imsgev	iev_pop3e;

const char		*mpath;

int			mtype = M_MBOX;

int

main(int argc, char *argv[])

{

	struct passwd	*pw;

	struct event	ev_sigint, ev_sigterm, ev_sighup, ev_sigchld;

	const char	*path = NULL, *mtype_str = "mbox";

	const char	*cert = CERTFILE, *key = KEYFILE;

	int		ch, d = 0, pair[2];

	while ((ch = getopt(argc, argv, "c:dk:p:t:")) != -1) {

		switch (ch) {

		case 'c':

			cert = optarg;

			break;

		case 'd':

			d = 1;

			break;

		case 'k':

			key = optarg;

			break;

		case 'p':

			path = optarg;

			break;

		case 't':

			if ((mtype = m_type(optarg)) == -1)

				errx(1, "%s invalid argument", optarg);

			mtype_str = optarg;

			break;

		default:

			usage();

		}

	}

	argc -= optind;

	argv += optind;

	if (argc > 0 || *argv)

		usage();

	if (path)

		mpath = path;

	else

		mpath = (mtype == M_MAILDIR) ? MAILDIR_PATH : MBOX_PATH;

	log_init(d);

	if (geteuid())

		fatalx("need root privileges");

	if (!d && daemon(1, 0) == -1)

		fatal("failed to daemonize");

	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) == -1)

		fatal("socketpair");

	set_nonblocking(pair[0]);

	set_nonblocking(pair[1]);

	if ((pw = getpwnam(POP3D_USER)) == NULL)

		fatalx("main: getpwnam " POP3D_USER);

	pop3_main(pair, pw, cert, key);

	close(pair[1]);

	setproctitle("[priv]");

	logit(LOG_INFO, "pop3d ready; type:%s, path:%s", mtype_str, mpath);

	event_init();

	signal_set(&ev_sigint, SIGINT, sig_handler, NULL);

	signal_set(&ev_sighup, SIGHUP, sig_handler, NULL);

	signal_set(&ev_sigterm, SIGTERM, sig_handler, NULL);

	signal_set(&ev_sigchld, SIGCHLD, sig_handler, NULL);

	signal_add(&ev_sigint, NULL);

	signal_add(&ev_sighup, NULL);

	signal_add(&ev_sigterm, NULL);

	signal_add(&ev_sigchld, NULL);

	imsgev_init(&iev_pop3e, pair[0], NULL, pop3e_imsgev, needfd);

	if (event_dispatch() < 0)

		fatal("event_dispatch");

	logit(LOG_INFO, "pop3d exiting");

	return (0);

}

static void

pop3e_imsgev(struct imsgev *iev, int code, struct imsg *imsg)

{

	switch (code) {

	case IMSGEV_IMSG:

		switch (imsg->hdr.type) {

		case IMSG_AUTH:

			authenticate(iev, imsg);

			break;

		default:

			logit(LOG_DEBUG, "%s: unexpected imsg %u",

			    __func__, imsg->hdr.type);

			break;

		}

		break;

	case IMSGEV_EREAD:

	case IMSGEV_EWRITE:

	case IMSGEV_EIMSG:

		fatal("pop3d: imsgev read/write error");

		break;

	case IMSGEV_DONE:

		event_loopexit(NULL);

		break;

	}

}

static void

authenticate(struct imsgev *iev, struct imsg *imsg)

{

	struct auth_req	*req = imsg->data;

	struct passwd	*pw;

	int		pair[2];

	if (auth_userokay(req->user, NULL, "auth-pop3", req->pass) == 0) {

		logit(LOG_INFO, "%u: auth [%s] failed",

		    imsg->hdr.peerid, req->user);

		pair[0] = -1;

		goto end;

	}

	logit(LOG_INFO, "%u: auth [%s] passed", imsg->hdr.peerid,

	    req->user);

	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) == -1)

		fatal("socketpair");

	set_nonblocking(pair[0]);

	set_nonblocking(pair[1]);

	if ((pw = getpwnam(req->user)) == NULL)

		fatalx("authenticate: getpwnam");

	if (maildrop_setup(imsg->hdr.peerid, pair, pw) == -1) {

		logit(LOG_INFO, "%u: unable to fork maildrop process",

		    imsg->hdr.peerid);

		close(pair[0]);

		close(pair[1]);

		pair[0] = -1;

		goto end;

	}

	close(pair[1]);

end:

	imsgev_xcompose(iev, IMSG_AUTH, imsg->hdr.peerid, 0,

	    pair[0], NULL, 0, "authenticate");

}

static void

needfd(struct imsgev *iev)

{

	fatalx("pop3d should never need an fd");

}

static void

sig_handler(int sig, short event, void *arg)

{

	int status;

	switch (sig) {

	case SIGINT:

	case SIGHUP:

	case SIGTERM:

		imsgev_clear(&iev_pop3e);

		event_loopexit(NULL);

		break;

	case SIGCHLD:

		if (waitpid(WAIT_ANY, &status, WNOHANG) > 0)

			if ((WIFEXITED(status) && WEXITSTATUS(status) != 0) ||

			    WIFSIGNALED(status)) {

				logit(LOG_ERR, "Lost pop3 engine");

				event_loopexit(NULL);

			}

		break;

	}

}

static enum m_type

m_type(const char *str)

{

	if (strcasecmp(str, "mbox") == 0)

		return M_MBOX;

	if (strcasecmp(str, "maildir") == 0)

		return M_MAILDIR;

	return (-1);

}

static void

usage(void)

{

	extern char *__progname;

	fprintf(stderr, "usage: %s [-c certfile] [-d] "

	    "[-k keyfile] [-p path] [-t type]\n", __progname);

	exit(EXIT_FAILURE);

}