/*
 * Copyright (c) 2016, 2019, 2020-2021 Tracey Emery <tracey@traceyemery.net>
 * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
 * Copyright (c) 2013 David Gwynne <dlg@openbsd.org>
 * Copyright (c) 2013 Florian Obser <florian@openbsd.org>
 *
 * 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/ioctl.h>
#include <sys/queue.h>
#include <sys/wait.h>
#include <sys/uio.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/un.h>

#include <net/if.h>
#include <netinet/in.h>

#include <errno.h>
#include <event.h>
#include <fcntl.h>
#include <ifaddrs.h>
#include <imsg.h>
#include <limits.h>
#include <netdb.h>
#include <poll.h>
#include <pwd.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

#include "got_error.h"
#include "got_opentemp.h"
#include "got_reference.h"
#include "got_repository.h"

#include "proc.h"
#include "gotwebd.h"
#include "tmpl.h"

#define SOCKS_BACKLOG 5
#define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))


volatile int client_cnt;

static struct timeval	timeout = { TIMEOUT_DEFAULT, 0 };

static void	 sockets_sighdlr(int, short, void *);
static void	 sockets_run(struct privsep *, struct privsep_proc *, void *);
static void	 sockets_launch(void);
static void	 sockets_purge(struct gotwebd *);
static void	 sockets_accept_paused(int, short, void *);
static void	 sockets_rlimit(int);

static int	 sockets_dispatch_gotwebd(int, struct privsep_proc *,
		    struct imsg *);
static int	 sockets_unix_socket_listen(struct privsep *, struct socket *);
static int	 sockets_create_socket(struct address *, in_port_t);
static int	 sockets_accept_reserve(int, struct sockaddr *, socklen_t *,
		    int, volatile int *);

static struct socket *sockets_conf_new_socket_unix(struct gotwebd *,
		    struct server *, int);
static struct socket *sockets_conf_new_socket_fcgi(struct gotwebd *,
		    struct server *, int, struct address *);

int cgi_inflight = 0;

static struct privsep_proc procs[] = {
	{ "gotwebd",	PROC_GOTWEBD,	sockets_dispatch_gotwebd  },
};

void
sockets(struct privsep *ps, struct privsep_proc *p)
{
	proc_run(ps, p, procs, nitems(procs), sockets_run, NULL);
}

static void
sockets_run(struct privsep *ps, struct privsep_proc *p, void *arg)
{
	if (config_init(ps->ps_env) == -1)
		fatal("failed to initialize configuration");

	p->p_shutdown = sockets_shutdown;

	sockets_rlimit(-1);

	signal_del(&ps->ps_evsigchld);
	signal_set(&ps->ps_evsigchld, SIGCHLD, sockets_sighdlr, ps);
	signal_add(&ps->ps_evsigchld, NULL);

#ifndef PROFILE
	if (pledge("stdio rpath wpath cpath inet recvfd proc exec sendfd",
	    NULL) == -1)
		fatal("pledge");
#endif
}

void
sockets_parse_sockets(struct gotwebd *env)
{
	struct server *srv;
	struct address *a;
	struct socket *new_sock = NULL;
	int sock_id = 1;

	TAILQ_FOREACH(srv, &env->servers, entry) {
		if (srv->unix_socket) {
			new_sock = sockets_conf_new_socket_unix(env, srv,
			    sock_id);
			if (new_sock) {
				sock_id++;
				TAILQ_INSERT_TAIL(&env->sockets, new_sock,
				    entry);
			}
		}

		if (srv->fcgi_socket) {
			if (TAILQ_EMPTY(&srv->al)) {
				fatalx("%s: server %s has no IP addresses to "
				    "listen for FCGI connections", __func__,
				    srv->name);
			}
			TAILQ_FOREACH(a, &srv->al, entry) {
				if (a->ss.ss_family != AF_INET &&
				    a->ss.ss_family != AF_INET6)
					continue;
				new_sock = sockets_conf_new_socket_fcgi(env,
				    srv, sock_id, a);
				if (new_sock) {
					sock_id++;
					TAILQ_INSERT_TAIL(&env->sockets,
					    new_sock, entry);
				}
			}
		}
	}
}

static struct socket *
sockets_conf_new_socket_unix(struct gotwebd *env, struct server *srv, int id)
{
	struct socket *sock;
	int n;

	if ((sock = calloc(1, sizeof(*sock))) == NULL)
		fatalx("%s: calloc", __func__);

	sock->conf.id = id;
	sock->fd = -1;
	sock->conf.af_type = AF_UNIX;

	if (strlcpy(sock->conf.unix_socket_name,
	    srv->unix_socket_name,
	    sizeof(sock->conf.unix_socket_name)) >=
	    sizeof(sock->conf.unix_socket_name)) {
		free(sock);
		fatalx("%s: strlcpy", __func__);
	}

	n = snprintf(sock->conf.name, GOTWEBD_MAXTEXT, "%s_parent",
	    srv->name);
	if (n < 0 || (size_t)n >= GOTWEBD_MAXTEXT) {
		free(sock);
		fatalx("%s: snprintf", __func__);
	}

	if (strlcpy(sock->conf.srv_name, srv->name,
	    sizeof(sock->conf.srv_name)) >= sizeof(sock->conf.srv_name)) {
		free(sock);
		fatalx("%s: strlcpy", __func__);
	}

	return sock;
}

static struct socket *
sockets_conf_new_socket_fcgi(struct gotwebd *env, struct server *srv, int id,
    struct address *a)
{
	struct socket *sock;
	struct address *acp;
	int n;

	if ((sock = calloc(1, sizeof(*sock))) == NULL)
		fatalx("%s: calloc", __func__);

	sock->conf.id = id;
	sock->fd = -1;
	sock->conf.af_type = a->ss.ss_family;

	sock->conf.fcgi_socket_port = a->port;

	n = snprintf(sock->conf.name, GOTWEBD_MAXTEXT, "%s_parent",
	    srv->name);
	if (n < 0 || (size_t)n >= GOTWEBD_MAXTEXT) {
		free(sock);
		fatalx("%s: snprintf", __func__);
	}

	if (strlcpy(sock->conf.srv_name, srv->name,
	    sizeof(sock->conf.srv_name)) >= sizeof(sock->conf.srv_name)) {
		free(sock);
		fatalx("%s: strlcpy", __func__);
	}

	acp = &sock->conf.addr;

	memcpy(&acp->ss, &a->ss, sizeof(acp->ss));
	acp->ipproto = a->ipproto;
	acp->prefixlen = a->prefixlen;
	acp->port = a->port;
	if (strlen(a->ifname) != 0) {
		if (strlcpy(acp->ifname, a->ifname,
		    sizeof(acp->ifname)) >= sizeof(acp->ifname)) {
			fatalx("%s: interface name truncated",
			    __func__);
		}
	}

	return (sock);
}

static void
sockets_launch(void)
{
	struct socket *sock;

	TAILQ_FOREACH(sock, &gotwebd_env->sockets, entry) {
		log_debug("%s: configuring socket %d (%d)", __func__,
		    sock->conf.id, sock->fd);

		event_set(&sock->ev, sock->fd, EV_READ | EV_PERSIST,
		    sockets_socket_accept, sock);

		if (event_add(&sock->ev, NULL))
			fatalx("event add sock");

		evtimer_set(&sock->pause, sockets_accept_paused, sock);

		log_debug("%s: running socket listener %d", __func__,
		    sock->conf.id);
	}
}

static void
sockets_purge(struct gotwebd *env)
{
	struct socket *sock, *tsock;

	/* shutdown and remove sockets */
	TAILQ_FOREACH_SAFE(sock, &env->sockets, entry, tsock) {
		if (event_initialized(&sock->ev))
			event_del(&sock->ev);
		if (evtimer_initialized(&sock->evt))
			evtimer_del(&sock->evt);
		if (evtimer_initialized(&sock->pause))
			evtimer_del(&sock->pause);
		if (sock->fd != -1)
			close(sock->fd);
		TAILQ_REMOVE(&env->sockets, sock, entry);
	}
}

static int
sockets_dispatch_gotwebd(int fd, struct privsep_proc *p, struct imsg *imsg)
{
	struct privsep *ps = p->p_ps;
	int res = 0, cmd = 0, verbose;

	switch (imsg->hdr.type) {
	case IMSG_CFG_SRV:
		config_getserver(gotwebd_env, imsg);
		break;
	case IMSG_CFG_SOCK:
		config_getsock(gotwebd_env, imsg);
		break;
	case IMSG_CFG_FD:
		config_getfd(gotwebd_env, imsg);
		break;
	case IMSG_CFG_DONE:
		config_getcfg(gotwebd_env, imsg);
		break;
	case IMSG_CTL_START:
		sockets_launch();
		break;
	case IMSG_CTL_VERBOSE:
		IMSG_SIZE_CHECK(imsg, &verbose);
		memcpy(&verbose, imsg->data, sizeof(verbose));
		log_setverbose(verbose);
		break;
	default:
		return -1;
	}

	switch (cmd) {
	case 0:
		break;
	default:
		if (proc_compose_imsg(ps, PROC_GOTWEBD, -1, cmd,
		    imsg->hdr.peerid, -1, &res, sizeof(res)) == -1)
			return -1;
		break;
	}

	return 0;
}

static void
sockets_sighdlr(int sig, short event, void *arg)
{
	switch (sig) {
	case SIGHUP:
		log_info("%s: ignoring SIGHUP", __func__);
		break;
	case SIGPIPE:
		log_info("%s: ignoring SIGPIPE", __func__);
		break;
	case SIGUSR1:
		log_info("%s: ignoring SIGUSR1", __func__);
		break;
	case SIGCHLD:
		break;
	default:
		log_info("SIGNAL: %d", sig);
		fatalx("unexpected signal");
	}
}

void
sockets_shutdown(void)
{
	struct server *srv, *tsrv;
	struct socket *sock, *tsock;
	int i;

	sockets_purge(gotwebd_env);

	/* clean sockets */
	TAILQ_FOREACH_SAFE(sock, &gotwebd_env->sockets, entry, tsock) {
		TAILQ_REMOVE(&gotwebd_env->sockets, sock, entry);
		close(sock->fd);
		free(sock);
	}

	/* clean servers */
	TAILQ_FOREACH_SAFE(srv, &gotwebd_env->servers, entry, tsrv) {
		for (i = 0; i < srv->ncached_repos; i++)
			got_repo_close(srv->cached_repos[i].repo);
		free(srv);
	}

	free(gotwebd_env);
}

int
sockets_privinit(struct gotwebd *env, struct socket *sock)
{
	struct privsep *ps = env->gotwebd_ps;

	if (sock->conf.af_type == AF_UNIX) {
		log_debug("%s: initializing unix socket %s", __func__,
		    sock->conf.unix_socket_name);
		sock->fd = sockets_unix_socket_listen(ps, sock);
		if (sock->fd == -1) {
			log_warnx("%s: create unix socket failed", __func__);
			return -1;
		}
	}

	if (sock->conf.af_type == AF_INET || sock->conf.af_type == AF_INET6) {
		log_debug("%s: initializing %s FCGI socket on port %d for %s",
		    __func__, sock->conf.af_type == AF_INET ? "inet" : "inet6",
		    sock->conf.fcgi_socket_port, sock->conf.name);
		sock->fd = sockets_create_socket(&sock->conf.addr,
		    sock->conf.fcgi_socket_port);
		if (sock->fd == -1) {
			log_warnx("%s: create FCGI socket failed", __func__);
			return -1;
		}
	}

	return 0;
}

static int
sockets_unix_socket_listen(struct privsep *ps, struct socket *sock)
{
	struct gotwebd *env = ps->ps_env;
	struct sockaddr_un sun;
	struct socket *tsock;
	int u_fd = -1;
	mode_t old_umask, mode;

	TAILQ_FOREACH(tsock, &env->sockets, entry) {
		if (strcmp(tsock->conf.unix_socket_name,
		    sock->conf.unix_socket_name) == 0 &&
		    tsock->fd != -1)
			return (tsock->fd);
	}

	u_fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
	if (u_fd == -1) {
		log_warn("%s: socket", __func__);
		return -1;
	}

	sun.sun_family = AF_UNIX;
	if (strlcpy(sun.sun_path, sock->conf.unix_socket_name,
	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
		log_warn("%s: %s name too long", __func__,
		    sock->conf.unix_socket_name);
		close(u_fd);
		return -1;
	}

	if (unlink(sock->conf.unix_socket_name) == -1) {
		if (errno != ENOENT) {
			log_warn("%s: unlink %s", __func__,
			    sock->conf.unix_socket_name);
			close(u_fd);
			return -1;
		}
	}

	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP;

	if (bind(u_fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
		log_warn("%s: bind: %s", __func__, sock->conf.unix_socket_name);
		close(u_fd);
		(void)umask(old_umask);
		return -1;
	}

	(void)umask(old_umask);

	if (chmod(sock->conf.unix_socket_name, mode) == -1) {
		log_warn("%s: chmod", __func__);
		close(u_fd);
		(void)unlink(sock->conf.unix_socket_name);
		return -1;
	}

	if (chown(sock->conf.unix_socket_name, ps->ps_pw->pw_uid,
	    ps->ps_pw->pw_gid) == -1) {
		log_warn("%s: chown", __func__);
		close(u_fd);
		(void)unlink(sock->conf.unix_socket_name);
		return -1;
	}

	if (listen(u_fd, SOCKS_BACKLOG) == -1) {
		log_warn("%s: listen", __func__);
		return -1;
	}

	return u_fd;
}

static int
sockets_create_socket(struct address *a, in_port_t port)
{
	struct addrinfo hints;
	int fd = -1, o_val = 1, flags;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags |= AI_PASSIVE;

	switch (a->ss.ss_family) {
	case AF_INET:
		((struct sockaddr_in *)(&a->ss))->sin_port = htons(port);
		break;
	case AF_INET6:
		((struct sockaddr_in6 *)(&a->ss))->sin6_port = htons(port);
		break;
	default:
		log_warnx("%s: unknown address family", __func__);
		return -1;
	}

	fd = socket(a->ss.ss_family, hints.ai_socktype, a->ipproto);
	if (fd == -1)
		return -1;

	log_debug("%s: opened socket (%d) for %s", __func__,
	    fd, a->ifname);

	if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &o_val,
	    sizeof(int)) == -1) {
		log_warn("%s: setsockopt error", __func__);
		close(fd);
		return -1;
	}

	/* non-blocking */
	flags = fcntl(fd, F_GETFL);
	flags |= O_NONBLOCK;
	if (fcntl(fd, F_SETFL, flags) == -1) {
		log_info("%s: could not enable non-blocking I/O", __func__);
		close(fd);
		return -1;
	}

	if (bind(fd, (struct sockaddr *)&a->ss, a->ss.ss_len) == -1) {
		close(fd);
		log_info("%s: can't bind to port %d", __func__,
		    ntohs(port));
		return -1;
	}

	if (listen(fd, SOMAXCONN) == -1) {
		log_warn("%s, unable to listen on socket", __func__);
		close(fd);
		return -1;
	}

	return (fd);
}

static int
sockets_accept_reserve(int sockfd, struct sockaddr *addr, socklen_t *addrlen,
    int reserve, volatile int *counter)
{
	int ret;

	if (getdtablecount() + reserve +
	    ((*counter + 1) * FD_NEEDED) >= getdtablesize()) {
		log_debug("inflight fds exceeded");
		errno = EMFILE;
		return -1;
	}

	if ((ret = accept4(sockfd, addr, addrlen,
	    SOCK_NONBLOCK | SOCK_CLOEXEC)) > -1) {
		(*counter)++;
		log_debug("inflight incremented, now %d", *counter);
	}

	return ret;
}

static void
sockets_accept_paused(int fd, short events, void *arg)
{
	struct socket *sock = (struct socket *)arg;

	event_add(&sock->ev, NULL);
}

void
sockets_socket_accept(int fd, short event, void *arg)
{
	struct socket *sock = (struct socket *)arg;
	struct sockaddr_storage ss;
	struct timeval backoff;
	struct request *c = NULL;
	socklen_t len;
	int s;

	backoff.tv_sec = 1;
	backoff.tv_usec = 0;

	event_add(&sock->ev, NULL);
	if (event & EV_TIMEOUT)
		return;

	len = sizeof(ss);

	s = sockets_accept_reserve(fd, (struct sockaddr *)&ss, &len,
	    FD_RESERVE, &cgi_inflight);

	if (s == -1) {
		switch (errno) {
		case EINTR:
		case EWOULDBLOCK:
		case ECONNABORTED:
			return;
		case EMFILE:
		case ENFILE:
			event_del(&sock->ev);
			evtimer_add(&sock->pause, &backoff);
			return;
		default:
			log_warn("%s: accept", __func__);
		}
	}

	if (client_cnt > GOTWEBD_MAXCLIENTS)
		goto err;

	c = calloc(1, sizeof(struct request));
	if (c == NULL) {
		log_warn("%s", __func__);
		close(s);
		cgi_inflight--;
		return;
	}

	c->tp = template(c, fcgi_puts, fcgi_putc);
	if (c->tp == NULL) {
		log_warn("%s", __func__);
		close(s);
		cgi_inflight--;
		free(c);
		return;
	}

	c->fd = s;
	c->sock = sock;
	memcpy(c->priv_fd, sock->priv_fd, sizeof(c->priv_fd));
	c->buf_pos = 0;
	c->buf_len = 0;
	c->request_started = 0;
	c->sock->client_status = CLIENT_CONNECT;

	event_set(&c->ev, s, EV_READ|EV_PERSIST, fcgi_request, c);
	event_add(&c->ev, NULL);

	evtimer_set(&c->tmo, fcgi_timeout, c);
	evtimer_add(&c->tmo, &timeout);

	client_cnt++;

	return;
err:
	cgi_inflight--;
	close(s);
	if (c != NULL)
		free(c);
}

static void
sockets_rlimit(int maxfd)
{
	struct rlimit rl;

	if (getrlimit(RLIMIT_NOFILE, &rl) == -1)
		fatal("%s: failed to get resource limit", __func__);
	log_debug("%s: max open files %llu", __func__,
	    (unsigned long long)rl.rlim_max);

	/*
	 * Allow the maximum number of open file descriptors for this
	 * login class (which should be the class "daemon" by default).
	 */
	if (maxfd == -1)
		rl.rlim_cur = rl.rlim_max;
	else
		rl.rlim_cur = MAXIMUM(rl.rlim_max, (rlim_t)maxfd);
	if (setrlimit(RLIMIT_NOFILE, &rl) == -1)
		fatal("%s: failed to set resource limit", __func__);
}