ntp_intres.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

/*
 * ripped off from ../ntpres/ntpres.c by Greg Troxel 4/2/92
 * routine callable from ntpd, rather than separate program
 * also, key info passed in via a global, so no key file needed.
 */

/*
 * ntpres - process configuration entries which require use of the resolver
 *
 * This is meant to be run by ntpd on the fly.  It is not guaranteed
 * to work properly if run by hand.  This is actually a quick hack to
 * stave off violence from people who hate using numbers in the
 * configuration file (at least I hope the rest of the daemon is
 * better than this).  Also might provide some ideas about how one
 * might go about autoconfiguring an NTP distribution network.
 *
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include "ntp_machine.h"
#include "ntpd.h"
#include "ntp_io.h"
#include "ntp_request.h"
#include "ntp_stdlib.h"
#include "ntp_syslog.h"

#include <stdio.h>
#include <ctype.h>
#include <signal.h>

/**/
#include <netinet/in.h>
#include <arpa/inet.h>
/**/
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>		/* MAXHOSTNAMELEN (often) */
#endif

#include <isc/net.h>
#include <isc/result.h>

#define	STREQ(a, b)	(*(a) == *(b) && strcmp((a), (b)) == 0)

/*
 * Each item we are to resolve and configure gets one of these
 * structures defined for it.
 */
struct conf_entry {
	struct conf_entry *ce_next;
	char *ce_name;			/* name we are trying to resolve */
	struct conf_peer ce_config;	/* configuration info for peer */
	struct sockaddr_storage peer_store; /* address info for both fams */
};
#define	ce_peeraddr	ce_config.peeraddr
#define	ce_peeraddr6	ce_config.peeraddr6
#define	ce_hmode	ce_config.hmode
#define	ce_version	ce_config.version
#define ce_minpoll	ce_config.minpoll
#define ce_maxpoll	ce_config.maxpoll
#define	ce_flags	ce_config.flags
#define ce_ttl		ce_config.ttl
#define	ce_keyid	ce_config.keyid
#define ce_keystr	ce_config.keystr

/*
 * confentries is a pointer to the list of configuration entries
 * we have left to do.
 */
static struct conf_entry *confentries = NULL;

/*
 * We take an interrupt every thirty seconds, at which time we decrement
 * config_timer and resolve_timer.  The former is set to 2, so we retry
 * unsucessful reconfigurations every minute.  The latter is set to
 * an exponentially increasing value which starts at 2 and increases to
 * 32.  When this expires we retry failed name resolutions.
 *
 * We sleep SLEEPTIME seconds before doing anything, to give the server
 * time to arrange itself.
 */
#define	MINRESOLVE	2
#define	MAXRESOLVE	32
#define	CONFIG_TIME	2
#define	ALARM_TIME	30
#define	SLEEPTIME	2

static	volatile int config_timer = 0;
static	volatile int resolve_timer = 0;

static	int resolve_value;	/* next value of resolve timer */

/*
 * Big hack attack
 */
#define	LOCALHOST	0x7f000001	/* 127.0.0.1, in hex, of course */
#define	SKEWTIME	0x08000000	/* 0.03125 seconds as a l_fp fraction */

/*
 * Select time out.  Set to 2 seconds.  The server is on the local machine,
 * after all.
 */
#define	TIMEOUT_SEC	2
#define	TIMEOUT_USEC	0


/*
 * Input processing.  The data on each line in the configuration file
 * is supposed to consist of entries in the following order
 */
#define	TOK_HOSTNAME	0
#define	TOK_HMODE	1
#define	TOK_VERSION	2
#define TOK_MINPOLL	3
#define TOK_MAXPOLL	4
#define	TOK_FLAGS	5
#define TOK_TTL		6
#define	TOK_KEYID	7
#define TOK_KEYSTR	8
#define	NUMTOK		9

#define	MAXLINESIZE	512


/*
 * File descriptor for ntp request code.
 */
static	SOCKET sockfd = INVALID_SOCKET;	/* NT uses SOCKET */

/* stuff to be filled in by caller */

keyid_t req_keyid;	/* request keyid */
char *req_file;		/* name of the file with configuration info */

/* end stuff to be filled in */


static	RETSIGTYPE bong		P((int));
static	void	checkparent	P((void));
static	void	removeentry	P((struct conf_entry *));
static	void	addentry	P((char *, int, int, int, int, u_int,
				   int, keyid_t, char *));
static	int	findhostaddr	P((struct conf_entry *));
static	void	openntp		P((void));
static	int	request		P((struct conf_peer *));
static	char *	nexttoken	P((char **));
static	void	readconf	P((FILE *, char *));
static	void	doconfigure	P((int));

struct ntp_res_t_pkt {		/* Tagged packet: */
	void *tag;		/* For the caller */
	u_int32 paddr;		/* IP to look up, or 0 */
	char name[MAXHOSTNAMELEN]; /* Name to look up (if 1st byte is not 0) */
};

struct ntp_res_c_pkt {		/* Control packet: */
	char name[MAXHOSTNAMELEN];
	u_int32 paddr;
	int mode;
	int version;
	int minpoll;
	int maxpoll;
	u_int flags;
	int ttl;
	keyid_t keyid;
	u_char keystr[MAXFILENAME];
};


static void	resolver_exit P((int));

/*
 * Call here instead of just exiting
 */

static void resolver_exit (int code)
{
#ifdef SYS_WINNT
	ExitThread (code);	/* Just to kill the thread not the process */
#else
	exit (code);		/* fill the forked process */
#endif
}

/*
 * ntp_res_recv: Process an answer from the resolver
 */

void
ntp_res_recv(void)
{
	/*
	  We have data ready on our descriptor.
	  It may be an EOF, meaning the resolver process went away.
	  Otherwise, it will be an "answer".
	*/
}


/*
 * ntp_intres needs;
 *
 *	req_key(???), req_keyid, req_file valid
 *	syslog still open
 */

void
ntp_intres(void)
{
	FILE *in;
#ifdef HAVE_SIGSUSPEND
	sigset_t set;

	sigemptyset(&set);
#endif /* HAVE_SIGSUSPEND */

#ifdef DEBUG
	if (debug > 1) {
		msyslog(LOG_INFO, "NTP_INTRES running");
	}
#endif

	/* check out auth stuff */
	if (sys_authenticate) {
		if (!authistrusted(req_keyid)) {
			msyslog(LOG_ERR, "invalid request keyid %08x",
			    req_keyid );
			resolver_exit(1);
		}
	}

	/*
	 * Read the configuration info
	 * {this is bogus, since we are forked, but it is easier
	 * to keep this code - gdt}
	 */
	if ((in = fopen(req_file, "r")) == NULL) {
		msyslog(LOG_ERR, "can't open configuration file %s: %m",
			req_file);
		resolver_exit(1);
	}
	readconf(in, req_file);
	(void) fclose(in);

	if (!debug )
		(void) unlink(req_file);

	/*
	 * Sleep a little to make sure the server is completely up
	 */

	sleep(SLEEPTIME);

	/*
	 * Make a first cut at resolving the bunch
	 */
	doconfigure(1);
	if (confentries == NULL) {
		resolver_exit(0);
	}
	
	/*
	 * Here we've got some problem children.  Set up the timer
	 * and wait for it.
	 */
	resolve_value = resolve_timer = MINRESOLVE;
	config_timer = CONFIG_TIME;
#ifndef SYS_WINNT
	(void) signal_no_reset(SIGALRM, bong);
	alarm(ALARM_TIME);
#endif /* SYS_WINNT */

	for (;;) {
		if (confentries == NULL)
		    resolver_exit(0);

		checkparent();

		if (resolve_timer == 0) {
			if (resolve_value < MAXRESOLVE)
			    resolve_value <<= 1;
			resolve_timer = resolve_value;
#ifdef DEBUG
			if (debug > 2)
				msyslog(LOG_INFO, "resolve_timer: 0->%d", resolve_timer);
#endif
			config_timer = CONFIG_TIME;
			doconfigure(1);
			continue;
		} else if (config_timer == 0) {
			config_timer = CONFIG_TIME;
#ifdef DEBUG
			if (debug > 2)
				msyslog(LOG_INFO, "config_timer: 0->%d", config_timer);
#endif
			doconfigure(0);
			continue; 
		}
#ifndef SYS_WINNT
		/*
		 * There is a race in here.  Is okay, though, since
		 * all it does is delay things by 30 seconds.
		 */
# ifdef HAVE_SIGSUSPEND
		sigsuspend(&set);
# else
		sigpause(0);
# endif /* HAVE_SIGSUSPEND */
#else
		if (config_timer > 0)
		    config_timer--;
		if (resolve_timer > 0)
		    resolve_timer--;
		sleep(ALARM_TIME);
#endif /* SYS_WINNT */
	}
}


#ifndef SYS_WINNT
/*
 * bong - service and reschedule an alarm() interrupt
 */
static RETSIGTYPE
bong(
	int sig
	)
{
	if (config_timer > 0)
	    config_timer--;
	if (resolve_timer > 0)
	    resolve_timer--;
	alarm(ALARM_TIME);
}
#endif /* SYS_WINNT */

/*
 * checkparent - see if our parent process is still running
 *
 * No need to worry in the Windows NT environment whether the
 * main thread is still running, because if it goes
 * down it takes the whole process down with it (in
 * which case we won't be running this thread either)
 * Turn function into NOP;
 */

static void
checkparent(void)
{
#if !defined (SYS_WINNT) && !defined (SYS_VXWORKS)

	/*
	 * If our parent (the server) has died we will have been
	 * inherited by init.  If so, exit.
	 */
	if (getppid() == 1) {
		msyslog(LOG_INFO, "parent died before we finished, exiting");
		resolver_exit(0);
	}
#endif /* SYS_WINNT && SYS_VXWORKS*/
}



/*
 * removeentry - we are done with an entry, remove it from the list
 */
static void
removeentry(
	struct conf_entry *entry
	)
{
	register struct conf_entry *ce;

	ce = confentries;
	if (ce == entry) {
		confentries = ce->ce_next;
		return;
	}

	while (ce != NULL) {
		if (ce->ce_next == entry) {
			ce->ce_next = entry->ce_next;
			return;
		}
		ce = ce->ce_next;
	}
}


/*
 * addentry - add an entry to the configuration list
 */
static void
addentry(
	char *name,
	int mode,
	int version,
	int minpoll,
	int maxpoll,
	u_int flags,
	int ttl,
	keyid_t keyid,
	char *keystr
	)
{
	register char *cp;
	register struct conf_entry *ce;
	unsigned int len;

#ifdef DEBUG
	if (debug > 1)
		msyslog(LOG_INFO, 
		    "intres: <%s> %d %d %d %d %x %d %x %s\n", name,
		    mode, version, minpoll, maxpoll, flags, ttl, keyid,
		    keystr);
#endif
	len = strlen(name) + 1;
	cp = (char *)emalloc(len);
	memmove(cp, name, len);

	ce = (struct conf_entry *)emalloc(sizeof(struct conf_entry));
	ce->ce_name = cp;
	ce->ce_peeraddr = 0;
#ifdef ISC_PLATFORM_HAVEIPV6
	ce->ce_peeraddr6 = in6addr_any;
#endif
	ANYSOCK(&ce->peer_store);
	ce->ce_hmode = (u_char)mode;
	ce->ce_version = (u_char)version;
	ce->ce_minpoll = (u_char)minpoll;
	ce->ce_maxpoll = (u_char)maxpoll;
	ce->ce_flags = (u_char)flags;
	ce->ce_ttl = (u_char)ttl;
	ce->ce_keyid = keyid;
	strncpy((char *)ce->ce_keystr, keystr, MAXFILENAME);
	ce->ce_next = NULL;

	if (confentries == NULL) {
		confentries = ce;
	} else {
		register struct conf_entry *cep;

		for (cep = confentries; cep->ce_next != NULL;
		     cep = cep->ce_next)
		    /* nothing */;
		cep->ce_next = ce;
	}
}


/*
 * findhostaddr - resolve a host name into an address (Or vice-versa)
 *
 * Given one of {ce_peeraddr,ce_name}, find the other one.
 * It returns 1 for "success" and 0 for an uncorrectable failure.
 * Note that "success" includes try again errors.  You can tell that you
 *  got a "try again" since {ce_peeraddr,ce_name} will still be zero.
 */
static int
findhostaddr(
	struct conf_entry *entry
	)
{
	struct addrinfo *addr;
	struct addrinfo hints;
	int error;

	checkparent();		/* make sure our guy is still running */

	if (entry->ce_name != NULL && !SOCKNUL(&entry->peer_store)) {
		/* HMS: Squawk? */
		msyslog(LOG_ERR, "findhostaddr: both ce_name and ce_peeraddr are defined...");
		return 1;
	}

        if (entry->ce_name == NULL && SOCKNUL(&entry->peer_store)) {
		msyslog(LOG_ERR, "findhostaddr: both ce_name and ce_peeraddr are undefined!");
		return 0;
	}

	if (entry->ce_name) {
#ifdef DEBUG
		if (debug > 2)
			msyslog(LOG_INFO, "findhostaddr: Resolving <%s>",
				entry->ce_name);
#endif /* DEBUG */

		memset(&hints, 0, sizeof(hints));
		hints.ai_family = AF_UNSPEC;
		/*
		 * If the IPv6 stack is not available look only for IPv4 addresses
		 */
		if (isc_net_probeipv6() != ISC_R_SUCCESS)
			hints.ai_family = AF_INET;

		error = getaddrinfo(entry->ce_name, NULL, &hints, &addr);
		if (error == 0) {
			entry->peer_store = *((struct sockaddr_storage*)(addr->ai_addr));
			if (entry->peer_store.ss_family == AF_INET) {
				entry->ce_peeraddr =
				    GET_INADDR(entry->peer_store);
				entry->ce_config.v6_flag = 0;
			} else {
				entry->ce_peeraddr6 =
				    GET_INADDR6(entry->peer_store);
				entry->ce_config.v6_flag = 1;
			}
		}
	} else {
#ifdef DEBUG
		if (debug > 2)
			msyslog(LOG_INFO, "findhostaddr: Resolving %s>",
				stoa(&entry->peer_store));
#endif
		entry->ce_name = emalloc(MAXHOSTNAMELEN);
		error = getnameinfo((const struct sockaddr *)&entry->peer_store,
				   SOCKLEN(&entry->peer_store),
				   (char *)&entry->ce_name, MAXHOSTNAMELEN,
				   NULL, 0, 0);
	}

	if (error != 0) {
		/*
		 * If the resolver is in use, see if the failure is
		 * temporary.  If so, return success.
		 */
		if (error == EAI_AGAIN)
		    return (1);
		return (0);
	}

	if (entry->ce_name) {
#ifdef DEBUG
		if (debug > 2)
			msyslog(LOG_INFO, "findhostaddr: name resolved.");
#endif

#ifdef DEBUG
		if (debug > 2)
			msyslog(LOG_INFO, "findhostaddr: address resolved.");
#endif
	}
		   
	return (1);
}


/*
 * openntp - open a socket to the ntp server
 */
static void