source: trunk/minix/lib/ip/gethostent.c@ 20

/*      gethostent() - Interface to /etc/hosts          Author: Kees J. Bot
 *                                                              31 May 1999
 */

/* Prefix the functions defined here with underscores to distinguish them
 * from the newer replacements in the resolver library.
 */
#define sethostent      _sethostent
#define endhostent      _endhostent
#define gethostent      _gethostent
#define gethostbyname   _gethostbyname
#define gethostbyaddr   _gethostbyaddr

#define nil 0
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <net/gen/netdb.h>
#include <net/gen/in.h>
#include <net/gen/inet.h>
#include <net/gen/socket.h>

#define arraysize(a)    (sizeof(a) / sizeof((a)[0]))
#define arraylimit(a)   ((a) + arraysize(a))
#define isspace(c)      ((unsigned) (c) <= ' ')

static char HOSTS[]= _PATH_HOSTS;
static char *hosts= HOSTS;      /* Current hosts file. */
static FILE *hfp;               /* Open hosts file. */

void sethostent(int stayopen)
/* Start search.  (Same as ending it.) */
{
    endhostent();
}

void endhostent(void)
/* End search and reinitialize. */
{
    if (hfp != nil) {
        fclose(hfp);
        hfp= nil;
    }
    hosts= _PATH_HOSTS;
}

struct hostent *gethostent(void)
/* Return the next entry from the hosts files. */
{
    static char line[256];      /* One line in a hosts file. */
    static ipaddr_t addr;       /* IP address found first on the line. */
    static char *names[16];     /* Pointers to the words on the line. */
    static char *addrs[2]= {    /* List of IP addresses (just one.) */
        (char *) &addr,
        nil,
    };
    static struct hostent host = {
        nil,                    /* h_name, will set to names[1]. */
        names + 2,              /* h_aliases, the rest of the names. */
        AF_INET,                /* h_addrtype */
        sizeof(ipaddr_t),       /* Size of an address in the address list. */
        addrs,                  /* List of IP addresses. */
    };
    static char nexthosts[128]; /* Next hosts file to include. */
    char *lp, **np;
    int c;

    for (;;) {
        if (hfp == nil) {
            /* No hosts file open, try to open the next one. */
            if (hosts == 0) return nil;
            if ((hfp= fopen(hosts, "r")) == nil) { hosts= nil; continue; }
        }

        /* Read a line. */
        lp= line;
        while ((c= getc(hfp)) != EOF && c != '\n') {
            if (lp < arraylimit(line)) *lp++= c;
        }

        /* EOF?  Then close and prepare for reading the next file. */
        if (c == EOF) {
            fclose(hfp);
            hfp= nil;
            hosts= nil;
            continue;
        }

        if (lp == arraylimit(line)) continue;
        *lp= 0;

        /* Break the line up in words. */
        np= names;
        lp= line;
        for (;;) {
            while (isspace(*lp) && *lp != 0) lp++;
            if (*lp == 0 || *lp == '#') break;
            if (np == arraylimit(names)) break;
            *np++= lp;
            while (!isspace(*lp) && *lp != 0) lp++;
            if (*lp == 0) break;
            *lp++= 0;
        }

        if (np == arraylimit(names)) continue;
        *np= nil;

        /* Special "include file" directive. */
        if (np == names + 2 && strcmp(names[0], "include") == 0) {
            fclose(hfp);
            hfp= nil;
            hosts= nil;
            if (strlen(names[1]) < sizeof(nexthosts)) {
                strcpy(nexthosts, names[1]);
                hosts= nexthosts;
            }
            continue;
        }

        /* At least two words, the first of which is an IP address. */
        if (np < names + 2) continue;
        if (!inet_aton((char *) names[0], &addr)) continue;
        host.h_name= (char *) names[1];

        return &host;
    }
}

/* Rest kept in reserve, we probably never need 'em. */
#if XXX
struct hostent *gethostbyname(const char *name)
{
    struct hostent *he;
    char **pa;
    char alias[256];
    char *domain;
    
    sethostent(0);
    while ((he= gethostent()) != nil) {
        if (strcasecmp(he->h_name, name) == 0) goto found;

        domain= strchr(he->h_name, '.');
        for (pa= he->h_aliases; *pa != nil; pa++) {
            strcpy(alias, *pa);
            if (domain != nil && strchr(alias, '.') == nil) {
                strcat(alias, domain);
            }
            if (strcasecmp(alias, name) == 0) goto found;
        }
    }
  found:
    endhostent();
    return he;
}

struct hostent *gethostbyaddr(const char *addr, int len, int type)
{
    struct hostent *he;

    sethostent(0);
    while ((he= gethostent()) != nil) {
        if (he->h_name[0] == '%') continue;
        if (type == AF_INET && memcmp(he->h_addr, addr, len) == 0) break;
    }
    endhostent();
    return he;
}
#endif