openbsd_snmpd_ntpd/subagent_ntpd.c

/*	$OpenBSD: mib.c,v 1.9 2024/05/22 08:44:02 martijn Exp $	*/

/*
 * Copyright (c) 2025 Wolfgang Hottgenroth <woho@hottis.de>
 * Copyright (c) 2022 Martijn van Duren <martijn@openbsd.org>
 * Copyright (c) 2012 Joel Knight <joel@openbsd.org>
 * Copyright (c) 2007, 2008, 2012 Reyk Floeter <reyk@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/signal.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/un.h>

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <event.h>
#include <grp.h>
#include <pwd.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <libgen.h>
#include <limits.h>
// #include <agentx.h>   MUST BE INCLUDED ONLY ONCE, WILL BE INCLUDED IN mib.h
#include "mib.h"
#include "log.h"

struct event		 connev;

void		 snmp_connect(struct agentx *, void *, int);
void		 snmp_tryconnect(int, short, void *);
void		 snmp_read(int, short, void *);


int
main(int argc, char *argv[])
{
	struct agentx *sa;
  struct agentx_context *sac;
	struct agentx_session *sas;
	struct passwd *pw;
	struct group *gr;
	int ch;
	int verbose = 0, daemonize = 1;

	log_init(2, LOG_DAEMON);

	agentx_log_fatal = fatalx;
	agentx_log_warn = log_warnx;
	agentx_log_info = log_info;
	agentx_log_debug = log_debug;

	while ((ch = getopt(argc, argv, "dv")) != -1) {
		switch (ch) {
		case 'd':
			daemonize = 0;
			break;
		case 'v':
			verbose++;
			break;
		default:
			fatalx("usage: subagent_ntpd [-dv]\n");
		}
	}

	if ((pw = getpwnam("_snmpd")) == NULL)
		fatal("can't find _snmpd user");
	if ((gr = getgrnam("_agentx")) == NULL)
		fatal("can't find _agentx group");

	event_init();

	if ((sa = agentx(snmp_connect, NULL)) == NULL)
		fatal("agentx");
	if ((sas = agentx_session(sa, NULL, 0, "Hottis NTP Metrics for OpenNTPD", 0)) == NULL)
		fatal("agentx_session");
	if ((sac = agentx_context(sas, NULL)) == NULL)
		fatal("agentx_context");


	/* Can't pledge: kvm_getfiles */
	if (unveil(NULL, NULL) == -1)
		fatal("unveil");

	if (setgid(gr->gr_gid) == -1)
		fatal("setgid");
	if (setuid(pw->pw_uid) == -1)
		fatal("setuid");

  mib_register(sac);

	if (daemonize) {
		log_init(0, LOG_DAEMON);
		daemon(0, 0);
	}
	log_setverbose(verbose);

	event_dispatch();
}

void
snmp_connect(struct agentx *sa, void *cookie, int close)
{
	if (close) {
		event_del(&connev);
		return;
	}

  snmp_tryconnect(-1, 0, sa);
}

void
snmp_tryconnect(int fd, short event, void *cookie)
{
	struct timeval timeout = {3, 0};
	struct agentx *sa = cookie;
	struct sockaddr_un sun;

	sun.sun_len = sizeof(sun);
	sun.sun_family = AF_UNIX;
	strlcpy(sun.sun_path, AGENTX_MASTER_PATH, sizeof(sun.sun_path));

	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1 ||
	    connect(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
		if (fd != -1)
			close(fd);
		log_warn("Failed to connect to snmpd");
		evtimer_set(&connev, snmp_tryconnect, sa);
		evtimer_add(&connev, &timeout);
		return;
	}

	event_set(&connev, fd, EV_READ | EV_PERSIST, snmp_read, sa);
	event_add(&connev, NULL);

	agentx_connect(sa, fd);
}

void
snmp_read(int fd, short event, void *cookie)
{
	struct agentx *sa = cookie;

	agentx_read(sa);
}