getnameinfo.c

TCPDUMP的C语言源代码,是在数据链路层的应用

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Issues to be discussed:
 * - Thread safe-ness must be checked
 * - Return values.  There seems to be no standard for return value (RFC2553)
 *   but INRIA implementation returns EAI_xxx defined for getaddrinfo().
 * - RFC2553 says that we should raise error on short buffer.  X/Open says
 *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
 *   modified).
 */

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

#ifndef lint
static const char rcsid[] _U_ =
     "@(#) $Header: /tcpdump/master/tcpdump/missing/getnameinfo.c,v 1.11 2003-11-16 09:36:49 guy Exp $";
#endif

#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include <resolv.h>
#include <string.h>
#include <stddef.h>
#include <errno.h>

#ifdef NEED_ADDRINFO_H
#include "addrinfo.h"
#endif

#define SUCCESS 0
#define ANY 0
#define YES 1
#define NO  0

static struct afd {
	int a_af;
	int a_addrlen;
	int a_socklen;
	int a_off;
} afdl [] = {
#ifdef INET6
	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
		offsetof(struct sockaddr_in6, sin6_addr)},
#endif
	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
		offsetof(struct sockaddr_in, sin_addr)},
	{0, 0, 0},
};

struct sockinet {
	u_char	si_len;
	u_char	si_family;
	u_short	si_port;
};

#define ENI_NOSOCKET 	0
#define ENI_NOSERVNAME	1
#define ENI_NOHOSTNAME	2
#define ENI_MEMORY	3
#define ENI_SYSTEM	4
#define ENI_FAMILY	5
#define ENI_SALEN	6

int
getnameinfo(sa, salen, host, hostlen, serv, servlen, flags)
	const struct sockaddr *sa;
	size_t salen;
	char *host;
	size_t hostlen;
	char *serv;
	size_t servlen;
	int flags;
{
	struct afd *afd;
	struct servent *sp;
	struct hostent *hp;
	u_short port;
	int family, i;
	char *addr, *p;
	u_int32_t v4a;
	int h_error;
	char numserv[512];
	char numaddr[512];

	if (sa == NULL)
		return ENI_NOSOCKET;

#ifdef HAVE_SA_LEN	/*XXX*/
	if (sa->sa_len != salen)
		return ENI_SALEN;
#endif

	family = sa->sa_family;
	for (i = 0; afdl[i].a_af; i++)
		if (afdl[i].a_af == family) {
			afd = &afdl[i];
			goto found;
		}
	return ENI_FAMILY;

 found:
	if (salen != afd->a_socklen)
		return ENI_SALEN;

	port = ((struct sockinet *)sa)->si_port; /* network byte order */
	addr = (char *)sa + afd->a_off;

	if (serv == NULL || servlen == 0) {
		/*
		 * do nothing in this case.
		 * in case you are wondering if "&&" is more correct than
		 * "||" here: RFC2553 says that serv == NULL OR servlen == 0
		 * means that the caller does not want the result.
		 */
	} else {
		if (flags & NI_NUMERICSERV)
			sp = NULL;
		else {
			sp = getservbyport(port,
				(flags & NI_DGRAM) ? "udp" : "tcp");
		}
		if (sp) {
			if (strlen(sp->s_name) + 1 > servlen)
				return ENI_MEMORY;
			strcpy(serv, sp->s_name);
		} else {
			snprintf(numserv, sizeof(numserv), "%d", ntohs(port));
			if (strlen(numserv) + 1 > servlen)
				return ENI_MEMORY;
			strcpy(serv, numserv);
		}
	}

	switch (sa->sa_family) {
	case AF_INET:
		v4a = (u_int32_t)
			ntohl(((struct sockaddr_in *)sa)->sin_addr.s_addr);
		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
			flags |= NI_NUMERICHOST;
		v4a >>= IN_CLASSA_NSHIFT;
		if (v4a == 0)
			flags |= NI_NUMERICHOST;
		break;
#ifdef INET6
	case AF_INET6:
	    {
		struct sockaddr_in6 *sin6;
		sin6 = (struct sockaddr_in6 *)sa;
		switch (sin6->sin6_addr.s6_addr[0]) {
		case 0x00:
			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
				;
			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
				;
			else
				flags |= NI_NUMERICHOST;
			break;
		default:
			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
				flags |= NI_NUMERICHOST;
			}
			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
				flags |= NI_NUMERICHOST;
			break;
		}
	    }
		break;
#endif
	}
	if (host == NULL || hostlen == 0) {
		/*
		 * do nothing in this case.
		 * in case you are wondering if "&&" is more correct than
		 * "||" here: RFC2553 says that host == NULL OR hostlen == 0
		 * means that the caller does not want the result.
		 */
	} else if (flags & NI_NUMERICHOST) {
		/* NUMERICHOST and NAMEREQD conflicts with each other */
		if (flags & NI_NAMEREQD)
			return ENI_NOHOSTNAME;
		if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
		    == NULL)
			return ENI_SYSTEM;
		if (strlen(numaddr) + 1 > hostlen)
			return ENI_MEMORY;
		strcpy(host, numaddr);
#if defined(INET6) && defined(NI_WITHSCOPEID)
		if (afd->a_af == AF_INET6 &&
		    (IN6_IS_ADDR_LINKLOCAL((struct in6_addr *)addr) ||
		     IN6_IS_ADDR_MULTICAST((struct in6_addr *)addr)) &&
		    ((struct sockaddr_in6 *)sa)->sin6_scope_id) {
#ifndef ALWAYS_WITHSCOPE
			if (flags & NI_WITHSCOPEID)
#endif /* !ALWAYS_WITHSCOPE */
			{
				char *ep = strchr(host, '\0');
				unsigned int ifindex =
					((struct sockaddr_in6 *)sa)->sin6_scope_id;

				*ep = SCOPE_DELIMITER;
				if ((if_indextoname(ifindex, ep + 1)) == NULL)
					/* XXX what should we do? */
					strncpy(ep + 1, "???", 3);
			}
		}
#endif /* INET6 */
	} else {
#ifdef USE_GETIPNODEBY
		hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
#else
		hp = gethostbyaddr(addr, afd->a_addrlen, afd->a_af);
#ifdef HAVE_H_ERRNO
		h_error = h_errno;
#else
		h_error = EINVAL;
#endif
#endif

		if (hp) {
			if (flags & NI_NOFQDN) {
				p = strchr(hp->h_name, '.');
				if (p) *p = '\0';
			}
			if (strlen(hp->h_name) + 1 > hostlen) {
#ifdef USE_GETIPNODEBY
				freehostent(hp);
#endif
				return ENI_MEMORY;
			}
			strcpy(host, hp->h_name);
#ifdef USE_GETIPNODEBY
			freehostent(hp);
#endif
		} else {
			if (flags & NI_NAMEREQD)
				return ENI_NOHOSTNAME;
			if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
			    == NULL)
				return ENI_NOHOSTNAME;
			if (strlen(numaddr) + 1 > hostlen)
				return ENI_MEMORY;
			strcpy(host, numaddr);
		}
	}
	return SUCCESS;
}