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/*	$OpenBSD: control.c,v 1.4 2021/08/01 09:07:03 florian Exp $	*/
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/*
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 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
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 *
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 * Permission to use, copy, modify, and distribute this software for any
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 * purpose with or without fee is hereby granted, provided that the above
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 * copyright notice and this permission notice appear in all copies.
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 *
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 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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 */
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#include "compat.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/socket.h>
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#include <sys/uio.h>
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#include <sys/un.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "control.h"
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#include "minibuffer.h"
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#include "telescope.h"
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#include "utils.h"
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#include "ui.h"
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#define	CONTROL_BACKLOG	5
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struct {
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	struct event	ev;
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	struct event	evt;
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	int		fd;
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} control_state = {.fd = -1};
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struct ctl_conn {
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	TAILQ_ENTRY(ctl_conn)	entry;
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	struct imsgev		iev;
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};
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struct ctl_conn	*control_connbyfd(int);
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struct ctl_conn	*control_connbypid(pid_t);
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void		 control_close(int);
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TAILQ_HEAD(ctl_conns, ctl_conn) ctl_conns = TAILQ_HEAD_INITIALIZER(ctl_conns);
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int
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control_init(char *path)
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{
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	struct sockaddr_un	 sun;
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	int			 fd;
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	mode_t			 old_umask;
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	if ((fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
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	    0)) == -1) {
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		warn("%s: socket", __func__);
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		return (-1);
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	}
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	memset(&sun, 0, sizeof(sun));
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	sun.sun_family = AF_UNIX;
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	strlcpy(sun.sun_path, path, sizeof(sun.sun_path));
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	if (unlink(path) == -1)
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		if (errno != ENOENT) {
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			warn("%s: unlink %s", __func__, path);
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			close(fd);
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			return (-1);
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		}
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	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
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	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
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		warn("%s: bind: %s", __func__, path);
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		close(fd);
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		umask(old_umask);
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		return (-1);
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	}
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	umask(old_umask);
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	if (chmod(path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1) {
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		warn("%s: chmod", __func__);
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		close(fd);
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		(void)unlink(path);
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		return (-1);
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	}
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	return (fd);
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}
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int
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control_listen(int fd)
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{
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	control_state.fd = fd;
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	if (listen(control_state.fd, CONTROL_BACKLOG) == -1) {
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		warn("%s: listen", __func__);
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		return (-1);
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	}
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	event_set(&control_state.ev, control_state.fd, EV_READ,
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	    control_accept, NULL);
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	event_add(&control_state.ev, NULL);
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	evtimer_set(&control_state.evt, control_accept, NULL);
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	return (0);
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}
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void
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control_accept(int listenfd, short event, void *bula)
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{
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	int			 connfd;
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	socklen_t		 len;
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	struct sockaddr_un	 sun;
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	struct ctl_conn		*c;
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	event_add(&control_state.ev, NULL);
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	if ((event & EV_TIMEOUT))
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		return;
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	len = sizeof(sun);
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	if ((connfd = accept4(listenfd, (struct sockaddr *)&sun, &len,
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	    SOCK_CLOEXEC | SOCK_NONBLOCK)) == -1) {
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		/*
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		 * Pause accept if we are out of file descriptors, or
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		 * libevent will haunt us here too.
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		 */
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		if (errno == ENFILE || errno == EMFILE) {
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			struct timeval evtpause = { 1, 0 };
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			event_del(&control_state.ev);
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			evtimer_add(&control_state.evt, &evtpause);
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		} else if (errno != EWOULDBLOCK && errno != EINTR &&
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		    errno != ECONNABORTED)
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			message("%s: accept4: %s", __func__, strerror(errno));
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		return;
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	}
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	if ((c = calloc(1, sizeof(struct ctl_conn))) == NULL) {
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		message("%s: calloc: %s", __func__, strerror(errno));
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		close(connfd);
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		return;
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	}
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	imsg_init(&c->iev.ibuf, connfd);
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	c->iev.handler = control_dispatch_imsg;
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	c->iev.events = EV_READ;
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	event_set(&c->iev.ev, c->iev.ibuf.fd, c->iev.events,
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	    c->iev.handler, &c->iev);
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	event_add(&c->iev.ev, NULL);
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	TAILQ_INSERT_TAIL(&ctl_conns, c, entry);
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}
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struct ctl_conn *
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control_connbyfd(int fd)
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{
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	struct ctl_conn	*c;
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	TAILQ_FOREACH(c, &ctl_conns, entry) {
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		if (c->iev.ibuf.fd == fd)
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			break;
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	}
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	return (c);
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}
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struct ctl_conn *
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control_connbypid(pid_t pid)
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{
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	struct ctl_conn	*c;
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	TAILQ_FOREACH(c, &ctl_conns, entry) {
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		if (c->iev.ibuf.pid == pid)
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			break;
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	}
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	return (c);
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}
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void
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control_close(int fd)
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{
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	struct ctl_conn	*c;
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	if ((c = control_connbyfd(fd)) == NULL) {
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		message("%s: fd %d: not found", __func__, fd);
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		return;
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	}
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	msgbuf_clear(&c->iev.ibuf.w);
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	TAILQ_REMOVE(&ctl_conns, c, entry);
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	event_del(&c->iev.ev);
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	close(c->iev.ibuf.fd);
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	/* Some file descriptors are available again. */
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	if (evtimer_pending(&control_state.evt, NULL)) {
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		evtimer_del(&control_state.evt);
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		event_add(&control_state.ev, NULL);
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	}
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	free(c);
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}
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void
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control_dispatch_imsg(int fd, short event, void *bula)
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{
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	struct ctl_conn	*c;
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	struct imsg	 imsg;
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	ssize_t		 n;
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	if ((c = control_connbyfd(fd)) == NULL) {
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		message("%s: fd %d: not found", __func__, fd);
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		return;
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	}
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	if (event & EV_READ) {
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		if (((n = imsg_read(&c->iev.ibuf)) == -1 && errno != EAGAIN) ||
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		    n == 0) {
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			control_close(fd);
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			return;
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		}
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	}
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	if (event & EV_WRITE) {
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		if (msgbuf_write(&c->iev.ibuf.w) <= 0 && errno != EAGAIN) {
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			control_close(fd);
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			return;
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		}
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	}
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	for (;;) {
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		if ((n = imsg_get(&c->iev.ibuf, &imsg)) == -1) {
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			control_close(fd);
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			return;
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		}
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		if (n == 0)
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			break;
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		switch (imsg.hdr.type) {
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		case IMSG_CTL_OPEN_URL: {
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			static char uri[GEMINI_URL_LEN];
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			if (IMSG_DATA_SIZE(imsg) >= sizeof(uri))
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				break;
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			memset(uri, 0, sizeof(uri));
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			memcpy(uri, imsg.data, sizeof(uri));
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			if (uri[IMSG_DATA_SIZE(imsg)-1] != '\0')
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				break;
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			ui_remotely_open_link(uri);
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			break;
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		}
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		default:
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			message("%s: error handling imsg %d", __func__,
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			    imsg.hdr.type);
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			break;
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		}
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		imsg_free(&imsg);
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	}
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	imsg_event_add(&c->iev);
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}
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int
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control_imsg_relay(struct imsg *imsg)
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{
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	struct ctl_conn	*c;
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	if ((c = control_connbypid(imsg->hdr.pid)) == NULL)
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		return (0);
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	return (imsg_compose_event(&c->iev, imsg->hdr.type, 0, imsg->hdr.pid,
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	    -1, imsg->data, IMSG_DATA_SIZE(*imsg)));
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}