gethnamaddr.c

一个C源代码分析器

struct hostent *
gethostbyname(name)
	const char *name;
{
	querybuf buf;
	register const char *cp;
	int n;
	extern struct hostent *_gethtbyname();

	/*
	 * disallow names consisting only of digits/dots, unless
	 * they end in a dot.
	 */
	if (isdigit(name[0]))
		for (cp = name;; ++cp) {
			if (!*cp) {
				if (*--cp == '.')
					break;
				/*
				 * All-numeric, no dot at the end.
				 * Fake up a hostent as if we'd actually
				 * done a lookup.
				 */
				if (!inet_aton(name, &host_addr)) {
					h_errno = HOST_NOT_FOUND;
					return (NULL);
				}
				host.h_name = (char *)name;
				host.h_aliases = host_aliases;
				host_aliases[0] = NULL;
				host.h_addrtype = AF_INET;
				host.h_length = INT32SZ;
				h_addr_ptrs[0] = (char *)&host_addr;
				h_addr_ptrs[1] = NULL;
#if BSD >= 43 || defined(h_addr)	/* new-style hostent structure */
				host.h_addr_list = h_addr_ptrs;
#else
				host.h_addr = h_addr_ptrs[0];
#endif
				return (&host);
			}
			if (!isdigit(*cp) && *cp != '.') 
				break;
		}

	if ((n = res_search(name, C_IN, T_A, buf.buf, sizeof(buf))) < 0) {
#ifdef DEBUG
		if (_res.options & RES_DEBUG)
			printf("res_search failed\n");
#endif
		if (errno == ECONNREFUSED)
			return (_gethtbyname(name));
		else
			return (NULL);
	}
	return (getanswer(&buf, n, name, C_IN, T_A));
}

struct hostent *
gethostbyaddr(addr, len, type)
	const char *addr;
	int len, type;
{
	int n;
	querybuf buf;
	register struct hostent *hp;
	char qbuf[MAXDNAME+1];
#ifdef SUNSECURITY
	register struct hostent *rhp;
	char **haddr;
	u_long old_options;
#endif /*SUNSECURITY*/
	extern struct hostent *_gethtbyaddr();
	
	if (type != AF_INET)
		return (NULL);
	(void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
		((unsigned)addr[3] & 0xff),
		((unsigned)addr[2] & 0xff),
		((unsigned)addr[1] & 0xff),
		((unsigned)addr[0] & 0xff));
	n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
	if (n < 0) {
#ifdef DEBUG
		if (_res.options & RES_DEBUG)
			printf("res_query failed\n");
#endif
		if (errno == ECONNREFUSED)
			return (_gethtbyaddr(addr, len, type));
		return (NULL);
	}
	if (!(hp = getanswer(&buf, n, qbuf, C_IN, T_PTR)))
		return (NULL);
#ifdef SUNSECURITY
	/*
	 * turn off search as the name should be absolute,
	 * 'localhost' should be matched by defnames
	 */
	old_options = _res.options;
	_res.options &= ~RES_DNSRCH;
	_res.options |= RES_DEFNAMES;
	if (!(rhp = gethostbyname(hp->h_name))) {
		syslog(LOG_NOTICE|LOG_AUTH,
		       "gethostbyaddr: No A record for %s (verifying [%s])",
		       hp->h_name, inet_ntoa(*((struct in_addr *)addr)));
		_res.options = old_options;
		return (NULL);
	}
	_res.options = old_options;
	for (haddr = rhp->h_addr_list; *haddr; haddr++)
		if (!memcmp(*haddr, addr, INADDRSZ))
			break;
	if (!*haddr) {
		syslog(LOG_NOTICE|LOG_AUTH,
		       "gethostbyaddr: A record of %s != PTR record [%s]",
		       hp->h_name, inet_ntoa(*((struct in_addr *)addr)));
		h_errno = HOST_NOT_FOUND;
		return (NULL);
	}
#endif /*SUNSECURITY*/
	hp->h_addrtype = type;
	hp->h_length = len;
	h_addr_ptrs[0] = (char *)&host_addr;
	h_addr_ptrs[1] = NULL;
	host_addr = *(struct in_addr *)addr;
#if BSD < 43 && !defined(h_addr)	/* new-style hostent structure */
	hp->h_addr = h_addr_ptrs[0];
#endif
	return (hp);
}

void
_sethtent(f)
	int f;
{
	if (!hostf)
		hostf = fopen(_PATH_HOSTS, "r" );
	else
		rewind(hostf);
	stayopen = f;
}

void
_endhtent()
{
	if (hostf && !stayopen) {
		(void) fclose(hostf);
		hostf = NULL;
	}
}

struct hostent *
_gethtent()
{
	char *p;
	register char *cp, **q;

	if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" )))
		return (NULL);
again:
	if (!(p = fgets(hostbuf, sizeof hostbuf, hostf)))
		return (NULL);
	if (*p == '#')
		goto again;
	if (!(cp = strpbrk(p, "#\n")))
		goto again;
	*cp = '\0';
	if (!(cp = strpbrk(p, " \t")))
		goto again;
	*cp++ = '\0';
	/* THIS STUFF IS INTERNET SPECIFIC */
	if (!inet_aton(p, &host_addr))
		goto again;
	h_addr_ptrs[0] = (char *)&host_addr;
	h_addr_ptrs[1] = NULL;
#if BSD >= 43 || defined(h_addr)	/* new-style hostent structure */
	host.h_addr_list = h_addr_ptrs;
#else
	host.h_addr = h_addr_ptrs[0];
#endif
	host.h_length = INT32SZ;
	host.h_addrtype = AF_INET;
	while (*cp == ' ' || *cp == '\t')
		cp++;
	host.h_name = cp;
	q = host.h_aliases = host_aliases;
	if (cp = strpbrk(cp, " \t"))
		*cp++ = '\0';
	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (q < &host_aliases[MAXALIASES - 1])
			*q++ = cp;
		if (cp = strpbrk(cp, " \t"))
			*cp++ = '\0';
	}
	*q = NULL;
	return (&host);
}

struct hostent *
_gethtbyname(name)
	char *name;
{
	register struct hostent *p;
	register char **cp;
	
	_sethtent(0);
	while (p = _gethtent()) {
		if (strcasecmp(p->h_name, name) == 0)
			break;
		for (cp = p->h_aliases; *cp != 0; cp++)
			if (strcasecmp(*cp, name) == 0)
				goto found;
	}
found:
	_endhtent();
	return (p);
}

struct hostent *
_gethtbyaddr(addr, len, type)
	const char *addr;
	int len, type;
{
	register struct hostent *p;

	_sethtent(0);
	while (p = _gethtent())
		if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len))
			break;
	_endhtent();
	return (p);
}

#ifdef RESOLVSORT
static void
addrsort(ap, num)
	char **ap;
	int num;
{
	int i, j;
	char **p;
	short aval[MAXADDRS];
	int needsort = 0;

	p = ap;
	for (i = 0; i < num; i++, p++) {
	    for (j = 0 ; j < _res.nsort; j++)
		if (_res.sort_list[j].addr.s_addr == 
		    (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
			break;
	    aval[i] = j;
	    if (needsort == 0 && i > 0 && j < aval[i-1])
		needsort = i;
	}
	if (!needsort)
	    return;

	while (needsort < num) {
	    for (j = needsort - 1; j >= 0; j--) {
		if (aval[j] > aval[j+1]) {
		    char *hp;

		    i = aval[j];
		    aval[j] = aval[j+1];
		    aval[j+1] = i;

		    hp = ap[j];
		    ap[j] = ap[j+1];
		    ap[j+1] = hp;

		} else
		    break;
	    }
	    needsort++;
	}
}
#endif

#if defined(BSD43_BSD43_NFS) || defined(sun)
/* some libc's out there are bound internally to these names (UMIPS) */
void
ht_sethostent(stayopen)
	int stayopen;
{
	_sethtent(stayopen);
}

void
ht_endhostent()
{
	_endhtent();
}

struct hostent *
ht_gethostbyname(name)
	char *name;
{
	return (_gethtbyname(name));
}

struct hostent *
ht_gethostbyaddr(addr, len, type)
	const char *addr;
	int len, type;
{
	return (_gethtbyaddr(addr, len, type));
}

struct hostent *
gethostent()
{
	return (_gethtent());
}

void
dns_service()
{
	return;
}

#undef dn_skipname
dn_skipname(comp_dn, eom)
	const u_char *comp_dn, *eom;
{
	return (__dn_skipname(comp_dn, eom));
}
#endif /*old-style libc with yp junk in it*/

#ifdef ultrix
/* more icky libc packaging in ultrix */
int
local_hostname_length(hostname)
	const char *hostname;
{
	int len_host, len_domain;

	if (!*_res.defdname)
		res_init();
	len_host = strlen(hostname);
	len_domain = strlen(_res.defdname);
	if (len_host > len_domain &&
	    !strcasecmp(hostname + len_host - len_domain, _res.defdname) &&
	    hostname[len_host - len_domain - 1] == '.')
		return (len_host - len_domain - 1);
	return (0);
}
#endif