getservent.c

操作系统SunOS 4.1.3版本的源码

#if !defined(lint) && defined(SCCSIDS)
static  char sccsid[] = "@(#)getservent.c 1.1 92/07/30  Copyr 1990 Sun Micro";
#endif

/* 
 * Copyright (c) 1990 by Sun Microsystems, Inc.
 */

/* 
 * unlike gethost, getpw, etc, this doesn't implement getservbyxxx
 * directly
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <rpcsvc/ypclnt.h>

/*
 * Internet version.
 */
static struct servdata {
	FILE	*servf;
	char	*current;
	int	currentlen;
	int	stayopen;
#define MAXALIASES	35
	char	*serv_aliases[MAXALIASES];
	struct	servent serv;
	char	line[BUFSIZ+1];
	char	*domain;
	int	usingyellow;
} *servdata, *_servdata();

static struct servent *interpret();
struct servent *getservent();
char *inet_ntoa();
char *malloc();
static char *strpbrk();

static char *SERVDB = "/etc/services";
static char *YPMAP = "services.byname";

static struct servdata *
_servdata()
{
	register struct servdata *d = servdata;

	if (d == 0) {
		d = (struct servdata *)calloc(1, sizeof (struct servdata));
		servdata = d;
	}
	return (d);
}

struct servent *
getservbyport(svc_port, proto)
	int svc_port;
	char *proto;
{
	register struct servdata *d = _servdata();
	register struct servent *p = NULL;
	register u_short port = svc_port;
	register int status;

	if (d == 0)
		return (0);
	/*
	 * first try to do very fast NIS lookup.
	 */
	yellowup();
	if (d->usingyellow && (proto != 0)) {
		char portstr[12];
		char *key, *val;
		int keylen, vallen;
 
		sprintf(portstr, "%d", ntohs(port));
		keylen = strlen(portstr) + 1 + strlen(proto);
		key = malloc(keylen + 1);
		sprintf(key, "%s/%s", portstr, proto);
		if (!(status=yp_match(d->domain, YPMAP, key, keylen,
		    &val, &vallen))) {
			p = interpret(val, vallen);
			free(val);
			free(key);
			return(p);
		}
		free(key);
		if (yp_ismapthere(status)){
			return(p);
			}
			else d->usingyellow=0;
	}
	setservent(0);
	while (p = getservent()) {
		if (p->s_port != port)
			continue;
		if (proto == 0 || strcmp(p->s_proto, proto) == 0)
			break;
	}
	endservent();
	return (p);
}

struct servent *
getservbyname(name, proto)
	register char *name, *proto;
{
	register struct servdata *d = _servdata();
	register struct servent *p;
	register char **cp;

	if (d == 0)
		return (0);
	setservent(0);
	while (p = getservent()) {
		if (strcmp(name, p->s_name) == 0)
			goto gotname;
		for (cp = p->s_aliases; *cp; cp++)
			if (strcmp(name, *cp) == 0)
				goto gotname;
		continue;
gotname:
		if (proto == 0 || strcmp(p->s_proto, proto) == 0)
			break;
	}
	endservent();
	return (p);
}

setservent(f)
	int f;
{
	register struct servdata *d = _servdata();

	if (d == 0)
		return;
	if (d->servf == NULL)
		d->servf = fopen(SERVDB, "r");
	else
		rewind(d->servf);
	if (d->current)
		free(d->current);
	d->current = NULL;
	d->stayopen |= f;
	yellowup();	/* recompute whether NIS are up */
}

endservent()
{
	register struct servdata *d = _servdata();

	if (d == 0)
		return;
	if (d->current && !d->stayopen) {
		free(d->current);
		d->current = NULL;
	}
	if (d->servf && !d->stayopen) {
		fclose(d->servf);
		d->servf = NULL;
	}
}

struct servent *
getservent()
{
	register struct servdata *d = _servdata();
	int reason;
	char *key = NULL, *val = NULL;
	int keylen, vallen;
	struct servent *sp;

	if (d == 0)
		return NULL;
	yellowup();
	if (!d->usingyellow) {
		if (d->servf == NULL && (d->servf = fopen(SERVDB, "r")) == NULL)
			return (NULL);
		if (fgets(d->line, BUFSIZ, d->servf) == NULL)
			return (NULL);
		return interpret(d->line, strlen(d->line));
	}
	if (d->current == NULL) {
		if (reason =  yp_first(d->domain, YPMAP,
		    &key, &keylen, &val, &vallen)) {
		    if (yp_ismapthere(reason)==0) {
			d->usingyellow=0;
			return(getservent());
		    }
#ifdef DEBUG
			fprintf(stderr, "reason yp_first failed is %d\n",
			    reason);
#endif
			return NULL;
		    }
	}
	else {
		if (reason = yp_next(d->domain, YPMAP,
		    d->current, d->currentlen, &key, &keylen, &val, &vallen)) {
		    if (yp_ismapthere(reason)==0) {
			d->usingyellow=0;
			return(getservent());
		    }
#ifdef DEBUG
			fprintf(stderr, "reason yp_next failed is %d\n",
			    reason);
#endif
			return NULL;
		}
	}
	if (d->current)
		free(d->current);
	d->current = key;
	d->currentlen = keylen;
	sp = interpret(val, vallen);
	free(val);
	return (sp);
}

static struct servent *
interpret(val, len)
{
	register struct servdata *d = _servdata();
	char *p;
	register char *cp, **q;

	if (d == 0)
		return (0);
	strncpy(d->line, val, len);
	p = d->line;
	d->line[len] = '\n';
	if ((*p == '#') || (*p == '\n'))
		return (getservent());
	cp = strpbrk(p, "#\n");
	if (cp == NULL)
		return (getservent());
	*cp = '\0';
	d->serv.s_name = p;
	p = strpbrk(p, " \t");
	if (p == NULL)
		return (getservent());
	*p++ = '\0';
	while (*p == ' ' || *p == '\t')
		p++;
	cp = strpbrk(p, ",/");
	if (cp == NULL)
		return (getservent());
	*cp++ = '\0';
	d->serv.s_port = htons((u_short)atoi(p));
	d->serv.s_proto = cp;
	q = d->serv.s_aliases = d->serv_aliases;
	cp = strpbrk(cp, " \t");
	if (cp != NULL)
		*cp++ = '\0';
	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (q < &(d->serv_aliases[MAXALIASES - 1]))
			*q++ = cp;
		cp = strpbrk(cp, " \t");
		if (cp != NULL)
			*cp++ = '\0';
	}
	*q = NULL;
	return (&d->serv);
}

/*
 * check to see if NIS are up, and store that fact in d->usingyellow.
 */
static
yellowup()
{
	register struct servdata *d = _servdata();

	if (d->domain == NULL) {
		yp_get_default_domain(&d->domain);
		if (d->domain) d->usingyellow=1;
		else d->usingyellow=0;
	}
}