libbb/inet_common.c

/*
 * stolen from net-tools-1.59 and stripped down for busybox by
 *                      Erik Andersen <andersee@debian.org>
 *
 * Heavily modified by Manuel Novoa III       Mar 12, 2001
 *
 * Version:     $Id: inet_common.c,v 1.2 2002/06/06 12:11:55 andersen Exp $
 *
 */

#include "inet_common.h"
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "libbb.h"

#ifdef DEBUG
#include <resolv.h>
#endif


const char bb_INET_default[]="default";

int INET_resolve(const char *name, struct sockaddr_in *s_in, int hostfirst)
{
    struct hostent *hp;
    struct netent *np;

    /* Grmpf. -FvK */
    s_in->sin_family = AF_INET;
    s_in->sin_port = 0;

    /* Default is special, meaning 0.0.0.0. */
    if (!strcmp(name, bb_INET_default)) {
	s_in->sin_addr.s_addr = INADDR_ANY;
	return (1);
    }
    /* Look to see if it's a dotted quad. */
    if (inet_aton(name, &s_in->sin_addr)) {
	return 0;
    }
    /* If we expect this to be a hostname, try hostname database first */
#ifdef DEBUG
    if (hostfirst) fprintf (stderr, "gethostbyname (%s)\n", name);
#endif
    if (hostfirst &&
	(hp = gethostbyname(name)) != (struct hostent *) NULL) {
	memcpy((char *) &s_in->sin_addr, (char *) hp->h_addr_list[0],
		sizeof(struct in_addr));
	return 0;
    }
    /* Try the NETWORKS database to see if this is a known network. */
#ifdef DEBUG
    fprintf (stderr, "getnetbyname (%s)\n", name);
#endif
    if ((np = getnetbyname(name)) != (struct netent *) NULL) {
	s_in->sin_addr.s_addr = htonl(np->n_net);
	return 1;
    }
    if (hostfirst) {
	/* Don't try again */
	errno = h_errno;
	return -1;
    }
#ifdef DEBUG
    res_init();
    _res.options |= RES_DEBUG;
#endif

#ifdef DEBUG
    fprintf (stderr, "gethostbyname (%s)\n", name);
#endif
    if ((hp = gethostbyname(name)) == (struct hostent *) NULL) {
	errno = h_errno;
	return -1;
    }
    memcpy((char *) &s_in->sin_addr, (char *) hp->h_addr_list[0],
	   sizeof(struct in_addr));

    return 0;
}

/* cache */
struct addr {
    struct sockaddr_in addr;
    char *name;
    int host;
    struct addr *next;
};

static struct addr *INET_nn = NULL;     /* addr-to-name cache           */

/* numeric: & 0x8000: default instead of *,
 *          & 0x4000: host instead of net,
 *          & 0x0fff: don't resolve
 */
int INET_rresolve(char *name, size_t len, struct sockaddr_in *s_in,
			 int numeric, unsigned int netmask)
{
    struct hostent *ent;
    struct netent *np;
    struct addr *pn;
    unsigned long ad, host_ad;
    int host = 0;

    /* Grmpf. -FvK */
    if (s_in->sin_family != AF_INET) {
#ifdef DEBUG
	fprintf(stderr, "rresolve: unsupport address family %d !\n", s_in->sin_family);
#endif
	errno = EAFNOSUPPORT;
	return (-1);
    }
    ad = (unsigned long) s_in->sin_addr.s_addr;
#ifdef DEBUG
    fprintf (stderr, "rresolve: %08lx, mask %08x, num %08x \n", ad, netmask, numeric);
#endif
    if (ad == INADDR_ANY) {
	if ((numeric & 0x0FFF) == 0) {
	    if (numeric & 0x8000)
		safe_strncpy(name, bb_INET_default, len);
	    else
		safe_strncpy(name, "*", len);
	    return (0);
	}
    }
    if (numeric & 0x0FFF) {
	safe_strncpy(name, inet_ntoa(s_in->sin_addr), len);
	return (0);
    }

    if ((ad & (~netmask)) != 0 || (numeric & 0x4000))
	host = 1;
#if 0
    INET_nn = NULL;
#endif
    pn = INET_nn;
    while (pn != NULL) {
	if (pn->addr.sin_addr.s_addr == ad && pn->host == host) {
	    safe_strncpy(name, pn->name, len);
#ifdef DEBUG
	    fprintf (stderr, "rresolve: found %s %08lx in cache\n", (host? "host": "net"), ad);
#endif
	    return (0);
	}
	pn = pn->next;
    }

    host_ad = ntohl(ad);
    np = NULL;
    ent = NULL;
    if (host) {
#ifdef DEBUG
	fprintf (stderr, "gethostbyaddr (%08lx)\n", ad);
#endif
	ent = gethostbyaddr((char *) &ad, 4, AF_INET);
	if (ent != NULL)
	    safe_strncpy(name, ent->h_name, len);
    } else {
#ifdef DEBUG
	fprintf (stderr, "getnetbyaddr (%08lx)\n", host_ad);
#endif
	np = getnetbyaddr(host_ad, AF_INET);
	if (np != NULL)
	    safe_strncpy(name, np->n_name, len);
    }
    if ((ent == NULL) && (np == NULL))
	safe_strncpy(name, inet_ntoa(s_in->sin_addr), len);
    pn = (struct addr *) xmalloc(sizeof(struct addr));
    pn->addr = *s_in;
    pn->next = INET_nn;
    pn->host = host;
    pn->name = xstrdup(name);
    INET_nn = pn;

    return (0);
}