/*	$OpenBSD: rad.c,v 1.2 2018/07/10 22:14:19 florian Exp $	*/

/*
 * Copyright (c) 2018 Florian Obser <florian@openbsd.org>
 * Copyright (c) 2005 Claudio Jeker <claudio@openbsd.org>
 * Copyright (c) 2004 Esben Norby <norby@openbsd.org>
 * Copyright (c) 2003, 2004 Henning Brauer <henning@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/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/uio.h>
#include <sys/wait.h>

#include <netinet/in.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <netinet6/in6_var.h>
#include <netinet/icmp6.h>

#include <err.h>
#include <errno.h>
#include <event.h>
#include <imsg.h>
#include <netdb.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>

#include "log.h"
#include "rad.h"
#include "frontend.h"
#include "engine.h"
#include "control.h"

const char* imsg_type_name[] = {
	"IMSG_NONE",
	"IMSG_CTL_LOG_VERBOSE",
	"IMSG_RECONF_CONF",
	"IMSG_RECONF_RA_IFACE",
	"IMSG_RECONF_RA_AUTOPREFIX",
	"IMSG_RECONF_RA_PREFIX",
	"IMSG_RECONF_END",
	"IMSG_ICMP6SOCK",
	"IMSG_STARTUP",
	"IMSG_STARTUP_DONE",
	"IMSG_SOCKET_IPC",
};

__dead void	usage(void);
__dead void	main_shutdown(void);

void	main_sig_handler(int, short, void *);

static pid_t	start_child(int, char *, int, int, int, char *);

void	main_dispatch_frontend(int, short, void *);
void	main_dispatch_engine(int, short, void *);

static int	main_imsg_send_ipc_sockets(struct imsgbuf *, struct imsgbuf *);
static int	main_imsg_send_config(struct rad_conf *);

int	main_reload(void);
int	main_sendboth(enum imsg_type, void *, uint16_t);

void	free_ra_iface_conf(struct ra_iface_conf *);
void	in6_prefixlen2mask(struct in6_addr *, int len);

struct rad_conf	*main_conf;
struct imsgev		*iev_frontend;
struct imsgev		*iev_engine;
char			*conffile;
char			*csock;

pid_t	 frontend_pid;
pid_t	 engine_pid;

uint32_t cmd_opts;

void
main_sig_handler(int sig, short event, void *arg)
{
	/*
	 * Normal signal handler rules don't apply because libevent
	 * decouples for us.
	 */

	switch (sig) {
	case SIGTERM:
	case SIGINT:
		main_shutdown();
	case SIGHUP:
		if (main_reload() == -1)
			log_warnx("configuration reload failed");
		else
			log_debug("configuration reloaded");
		break;
	default:
		fatalx("unexpected signal");
	}
}

__dead void
usage(void)
{
	extern char *__progname;

	fprintf(stderr, "usage: %s [-dnv] [-f file] [-s socket]\n",
	    __progname);
	exit(1);
}

int
main(int argc, char *argv[])
{
	struct event		 ev_sigint, ev_sigterm, ev_sighup;
	struct icmp6_filter	 filt;
	int			 ch;
	int			 debug = 0, engine_flag = 0, frontend_flag = 0;
	char			*saved_argv0;
	int			 pipe_main2frontend[2];
	int			 pipe_main2engine[2];
	int			 icmp6sock, on = 1;

	conffile = CONF_FILE;
	csock = RAD_SOCKET;

	log_init(1, LOG_DAEMON);	/* Log to stderr until daemonized. */
	log_setverbose(1);

	saved_argv0 = argv[0];
	if (saved_argv0 == NULL)
		saved_argv0 = "rad";

	while ((ch = getopt(argc, argv, "dEFf:ns:v")) != -1) {
		switch (ch) {
		case 'd':
			debug = 1;
			break;
		case 'E':
			engine_flag = 1;
			break;
		case 'F':
			frontend_flag = 1;
			break;
		case 'f':
			conffile = optarg;
			break;
		case 'n':
			cmd_opts |= OPT_NOACTION;
			break;
		case 's':
			csock = optarg;
			break;
		case 'v':
			if (cmd_opts & OPT_VERBOSE)
				cmd_opts |= OPT_VERBOSE2;
			cmd_opts |= OPT_VERBOSE;
			break;
		default:
			usage();
		}
	}

	argc -= optind;
	argv += optind;
	if (argc > 0 || (engine_flag && frontend_flag))
		usage();

	if (engine_flag)
		engine(debug, cmd_opts & OPT_VERBOSE);
	else if (frontend_flag)
		frontend(debug, cmd_opts & OPT_VERBOSE, csock);

	/* parse config file */
	if ((main_conf = parse_config(conffile)) == NULL) {
		exit(1);
	}

	if (cmd_opts & OPT_NOACTION) {
		if (cmd_opts & OPT_VERBOSE)
			print_config(main_conf);
		else
			fprintf(stderr, "configuration OK\n");
		exit(0);
	}

	/* Check for root privileges. */
	if (geteuid())
		errx(1, "need root privileges");

	/* Check for assigned daemon user */
	if (getpwnam(RAD_USER) == NULL)
		errx(1, "unknown user %s", RAD_USER);

	log_init(debug, LOG_DAEMON);
	log_setverbose(cmd_opts & OPT_VERBOSE);

	if (!debug)
		daemon(1, 0);

	log_info("startup");

	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
	    PF_UNSPEC, pipe_main2frontend) == -1)
		fatal("main2frontend socketpair");
	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
	    PF_UNSPEC, pipe_main2engine) == -1)
		fatal("main2engine socketpair");

	/* Start children. */
	engine_pid = start_child(PROC_ENGINE, saved_argv0, pipe_main2engine[1],
	    debug, cmd_opts & OPT_VERBOSE, NULL);
	frontend_pid = start_child(PROC_FRONTEND, saved_argv0,
	    pipe_main2frontend[1], debug, cmd_opts & OPT_VERBOSE, csock);

	rad_process = PROC_MAIN;
	log_procinit(log_procnames[rad_process]);

	event_init();

	/* Setup signal handler. */
	signal_set(&ev_sigint, SIGINT, main_sig_handler, NULL);
	signal_set(&ev_sigterm, SIGTERM, main_sig_handler, NULL);
	signal_set(&ev_sighup, SIGHUP, main_sig_handler, NULL);
	signal_add(&ev_sigint, NULL);
	signal_add(&ev_sigterm, NULL);
	signal_add(&ev_sighup, NULL);
	signal(SIGPIPE, SIG_IGN);

	/* Setup pipes to children. */

	if ((iev_frontend = malloc(sizeof(struct imsgev))) == NULL ||
	    (iev_engine = malloc(sizeof(struct imsgev))) == NULL)
		fatal(NULL);
	imsg_init(&iev_frontend->ibuf, pipe_main2frontend[0]);
	iev_frontend->handler = main_dispatch_frontend;
	imsg_init(&iev_engine->ibuf, pipe_main2engine[0]);
	iev_engine->handler = main_dispatch_engine;

	/* Setup event handlers for pipes to engine & frontend. */
	iev_frontend->events = EV_READ;
	event_set(&iev_frontend->ev, iev_frontend->ibuf.fd,
	    iev_frontend->events, iev_frontend->handler, iev_frontend);
	event_add(&iev_frontend->ev, NULL);

	iev_engine->events = EV_READ;
	event_set(&iev_engine->ev, iev_engine->ibuf.fd, iev_engine->events,
	    iev_engine->handler, iev_engine);
	event_add(&iev_engine->ev, NULL);

	if (main_imsg_send_ipc_sockets(&iev_frontend->ibuf, &iev_engine->ibuf))
		fatal("could not establish imsg links");

	if ((icmp6sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC,
	    IPPROTO_ICMPV6)) < 0)
		fatal("ICMPv6 socket");

	if (setsockopt(icmp6sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on,
	    sizeof(on)) < 0)
		fatal("IPV6_RECVPKTINFO");

	if (setsockopt(icmp6sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on,
	    sizeof(on)) < 0)
		fatal("IPV6_RECVHOPLIMIT");

	/* only router advertisements and solicitations */
	ICMP6_FILTER_SETBLOCKALL(&filt);
	ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
	ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
	if (setsockopt(icmp6sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt,
	    sizeof(filt)) == -1)
		fatal("ICMP6_FILTER");

	main_imsg_compose_frontend_fd(IMSG_ICMP6SOCK, 0, icmp6sock);

	main_imsg_send_config(main_conf);

	if (pledge("stdio rpath cpath sendfd", NULL) == -1)
		fatal("pledge");

	event_dispatch();

	main_shutdown();
	return (0);
}

__dead void
main_shutdown(void)
{
	pid_t	 pid;
	int	 status;

	/* Close pipes. */
	msgbuf_clear(&iev_frontend->ibuf.w);
	close(iev_frontend->ibuf.fd);
	msgbuf_clear(&iev_engine->ibuf.w);
	close(iev_engine->ibuf.fd);

	config_clear(main_conf);

	log_debug("waiting for children to terminate");
	do {
		pid = wait(&status);
		if (pid == -1) {
			if (errno != EINTR && errno != ECHILD)
				fatal("wait");
		} else if (WIFSIGNALED(status))
			log_warnx("%s terminated; signal %d",
			    (pid == engine_pid) ? "engine" :
			    "frontend", WTERMSIG(status));
	} while (pid != -1 || (pid == -1 && errno == EINTR));

	free(iev_frontend);
	free(iev_engine);

	control_cleanup(csock);

	log_info("terminating");
	exit(0);
}

static pid_t
start_child(int p, char *argv0, int fd, int debug, int verbose, char *sockname)
{
	char	*argv[7];
	int	 argc = 0;
	pid_t	 pid;

	switch (pid = fork()) {
	case -1:
		fatal("cannot fork");
	case 0:
		break;
	default:
		close(fd);
		return (pid);
	}

	if (dup2(fd, 3) == -1)
		fatal("cannot setup imsg fd");

	argv[argc++] = argv0;
	switch (p) {
	case PROC_MAIN:
		fatalx("Can not start main process");
	case PROC_ENGINE:
		argv[argc++] = "-E";
		break;
	case PROC_FRONTEND:
		argv[argc++] = "-F";
		break;
	}
	if (debug)
		argv[argc++] = "-d";
	if (verbose)
		argv[argc++] = "-v";
	if (sockname) {
		argv[argc++] = "-s";
		argv[argc++] = sockname;
	}
	argv[argc++] = NULL;

	execvp(argv0, argv);
	fatal("execvp");
}

void
main_dispatch_frontend(int fd, short event, void *bula)
{
	struct imsgev		*iev = bula;
	struct imsgbuf		*ibuf;
	struct imsg		 imsg;
	ssize_t			 n;
	int			 shut = 0, verbose;

	ibuf = &iev->ibuf;

	if (event & EV_READ) {
		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
			fatal("imsg_read error");
		if (n == 0)	/* Connection closed. */
			shut = 1;
	}
	if (event & EV_WRITE) {
		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
			fatal("msgbuf_write");
		if (n == 0)	/* Connection closed. */
			shut = 1;
	}

	for (;;) {
		if ((n = imsg_get(ibuf, &imsg)) == -1)
			fatal("imsg_get");
		if (n == 0)	/* No more messages. */
			break;

		switch (imsg.hdr.type) {
		case IMSG_STARTUP_DONE:
			if (pledge("stdio rpath cpath", NULL) == -1)
				fatal("pledge");
			break;
		case IMSG_CTL_RELOAD:
			if (main_reload() == -1)
				log_warnx("configuration reload failed");
			else
				log_warnx("configuration reloaded");
			break;
		case IMSG_CTL_LOG_VERBOSE:
			/* Already checked by frontend. */
			memcpy(&verbose, imsg.data, sizeof(verbose));
			log_setverbose(verbose);
			break;
		default:
			log_debug("%s: error handling imsg %s", __func__,
			    imsg_type_name[imsg.hdr.type]);
			break;
		}
		imsg_free(&imsg);
	}
	if (!shut)
		imsg_event_add(iev);
	else {
		/* This pipe is dead. Remove its event handler */
		event_del(&iev->ev);
		event_loopexit(NULL);
	}
}

void
main_dispatch_engine(int fd, short event, void *bula)
{
	struct imsgev	*iev = bula;
	struct imsgbuf  *ibuf;
	struct imsg	 imsg;
	ssize_t		 n;
	int		 shut = 0;

	ibuf = &iev->ibuf;

	if (event & EV_READ) {
		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
			fatal("imsg_read error");
		if (n == 0)	/* Connection closed. */
			shut = 1;
	}
	if (event & EV_WRITE) {
		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
			fatal("msgbuf_write");
		if (n == 0)	/* Connection closed. */
			shut = 1;
	}

	for (;;) {
		if ((n = imsg_get(ibuf, &imsg)) == -1)
			fatal("imsg_get");
		if (n == 0)	/* No more messages. */
			break;

		switch (imsg.hdr.type) {
		default:
			log_debug("%s: error handling imsg %d", __func__,
			    imsg.hdr.type);
			break;
		}
		imsg_free(&imsg);
	}
	if (!shut)
		imsg_event_add(iev);
	else {
		/* This pipe is dead. Remove its event handler. */
		event_del(&iev->ev);
		event_loopexit(NULL);
	}
}

void
main_imsg_compose_frontend(int type, pid_t pid, void *data, uint16_t datalen)
{
	if (iev_frontend)
		imsg_compose_event(iev_frontend, type, 0, pid, -1, data,
		    datalen);
}

void
main_imsg_compose_frontend_fd(int type, pid_t pid, int fd)
{
	if (iev_frontend)
		imsg_compose_event(iev_frontend, type, 0, pid, fd, NULL, 0);
}


void
main_imsg_compose_engine(int type, pid_t pid, void *data, uint16_t datalen)
{
	if (iev_engine)
		imsg_compose_event(iev_engine, type, 0, pid, -1, data,
		    datalen);
}

void
imsg_event_add(struct imsgev *iev)
{
	iev->events = EV_READ;
	if (iev->ibuf.w.queued)
		iev->events |= EV_WRITE;

	event_del(&iev->ev);
	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev);
	event_add(&iev->ev, NULL);
}

int
imsg_compose_event(struct imsgev *iev, uint16_t type, uint32_t peerid,
    pid_t pid, int fd, void *data, uint16_t datalen)
{
	int	ret;

	if ((ret = imsg_compose(&iev->ibuf, type, peerid, pid, fd, data,
	    datalen)) != -1)
		imsg_event_add(iev);

	return (ret);
}

static int
main_imsg_send_ipc_sockets(struct imsgbuf *frontend_buf,
    struct imsgbuf *engine_buf)
{
	int pipe_frontend2engine[2];

	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
	    PF_UNSPEC, pipe_frontend2engine) == -1)
		return (-1);

	if (imsg_compose(frontend_buf, IMSG_SOCKET_IPC, 0, 0,
	    pipe_frontend2engine[0], NULL, 0) == -1)
		return (-1);
	if (imsg_compose(engine_buf, IMSG_SOCKET_IPC, 0, 0,
	    pipe_frontend2engine[1], NULL, 0) == -1)
		return (-1);

	return (0);
}

int
main_reload(void)
{
	struct rad_conf *xconf;

	if ((xconf = parse_config(conffile)) == NULL)
		return (-1);

	if (main_imsg_send_config(xconf) == -1)
		return (-1);

	merge_config(main_conf, xconf);

	return (0);
}

int
main_imsg_send_config(struct rad_conf *xconf)
{
	struct ra_iface_conf	*ra_iface_conf;
	struct ra_prefix_conf	*ra_prefix_conf;

	/* Send fixed part of config to children. */
	if (main_sendboth(IMSG_RECONF_CONF, xconf, sizeof(*xconf)) == -1)
		return (-1);

	/* Send the interface list to children. */
	SIMPLEQ_FOREACH(ra_iface_conf, &xconf->ra_iface_list, entry) {
		if (main_sendboth(IMSG_RECONF_RA_IFACE, ra_iface_conf,
		    sizeof(*ra_iface_conf)) == -1)
			return (-1);
		if (ra_iface_conf->autoprefix) {
			if (main_sendboth(IMSG_RECONF_RA_AUTOPREFIX,
			    ra_iface_conf->autoprefix,
			    sizeof(*ra_iface_conf->autoprefix)) == -1)
				return (-1);
		}
		SIMPLEQ_FOREACH(ra_prefix_conf, &ra_iface_conf->ra_prefix_list,
		    entry) {
			if (main_sendboth(IMSG_RECONF_RA_PREFIX,
			    ra_prefix_conf, sizeof(*ra_prefix_conf)) == -1)
				return (-1);
		}
	}

	/* Tell children the revised config is now complete. */
	if (main_sendboth(IMSG_RECONF_END, NULL, 0) == -1)
		return (-1);

	return (0);
}

int
main_sendboth(enum imsg_type type, void *buf, uint16_t len)
{
	if (imsg_compose_event(iev_frontend, type, 0, 0, -1, buf, len) == -1)
		return (-1);
	if (imsg_compose_event(iev_engine, type, 0, 0, -1, buf, len) == -1)
		return (-1);
	return (0);
}

void
free_ra_iface_conf(struct ra_iface_conf *ra_iface_conf)
{
	struct ra_prefix_conf	*prefix;

	if (!ra_iface_conf)
		return;

	free(ra_iface_conf->autoprefix);

	while ((prefix = SIMPLEQ_FIRST(&ra_iface_conf->ra_prefix_list))
	    != NULL) {
		SIMPLEQ_REMOVE_HEAD(&ra_iface_conf->ra_prefix_list, entry);
		free(prefix);
	}

	free(ra_iface_conf);
}

void
merge_config(struct rad_conf *conf, struct rad_conf *xconf)
{
	struct ra_iface_conf	*ra_iface_conf;

	conf->ra_options = xconf->ra_options;

	/* Remove & discard existing interfaces. */
	while ((ra_iface_conf = SIMPLEQ_FIRST(&conf->ra_iface_list)) != NULL) {
		SIMPLEQ_REMOVE_HEAD(&conf->ra_iface_list, entry);
		free_ra_iface_conf(ra_iface_conf);
	}

	/* Add new interfaces. */
	while ((ra_iface_conf = SIMPLEQ_FIRST(&xconf->ra_iface_list)) != NULL) {
		SIMPLEQ_REMOVE_HEAD(&xconf->ra_iface_list, entry);
		SIMPLEQ_INSERT_TAIL(&conf->ra_iface_list, ra_iface_conf, entry);
	}

	free(xconf);
}

struct rad_conf *
config_new_empty(void)
{
	struct rad_conf	*xconf;

	xconf = calloc(1, sizeof(*xconf));
	if (xconf == NULL)
		fatal(NULL);

	SIMPLEQ_INIT(&xconf->ra_iface_list);

	xconf->ra_options.dfr = 1;
	xconf->ra_options.cur_hl = 0;
	xconf->ra_options.m_flag = 0;
	xconf->ra_options.o_flag = 0;
	xconf->ra_options.router_lifetime = 1800;
	xconf->ra_options.reachable_time = 0;
	xconf->ra_options.retrans_timer = 0;

	return (xconf);
}

void
config_clear(struct rad_conf *conf)
{
	struct rad_conf	*xconf;

	/* Merge current config with an empty config. */
	xconf = config_new_empty();
	merge_config(conf, xconf);

	free(conf);
}

void mask_prefix(struct in6_addr* in6, int len)
{
	uint8_t	bitmask[8] = {0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe};
	int	i, skip;

	if (len < 0 || len > 128)
		fatalx("invalid prefix length: %d", len);

	skip = len / 8;

	in6->s6_addr[skip] &= bitmask[len % 8];

	for (i = skip + 1; i < 16; i++)
		in6->s6_addr[i] = 0;
}

const char*
sin6_to_str(struct sockaddr_in6 *sin6)
{
	static char hbuf[NI_MAXHOST];
	int error;

	error = getnameinfo((struct sockaddr *)sin6, sin6->sin6_len, hbuf,
	    sizeof(hbuf), NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV);
	if (error) {
		log_warnx("%s", gai_strerror(error));
		strlcpy(hbuf, "unknown", sizeof(hbuf));
	}
	return hbuf;
}

const char*
in6_to_str(struct in6_addr *in6)
{

	struct sockaddr_in6	sin6;

	memset(&sin6, 0, sizeof(sin6));
	sin6.sin6_len = sizeof(sin6);
	sin6.sin6_family = AF_INET6;
	sin6.sin6_addr = *in6;

	return (sin6_to_str(&sin6));
}