PC World Komputer 1999 March/PCWK3A99.iso/Linux/DDD331/DDD-3_1_.000/DDD-3_1_/ddd-3.1.1/ddd/hostname.C

C/C++ Source or Header | 1998-11-16 | 4.6 KB | 206 lines

// $Id: hostname.C,v 1.23 1998/11/16 13:41:26 zeller Exp $ -*- C++ -*-
// Return `official' name of host

// Copyright (C) 1995 Technische Universitaet Braunschweig, Germany.
// Written by Andreas Zeller <[e-mail]>.
//
// This file is part of DDD.
//
// DDD is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// DDD is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public
// License along with DDD -- see the file COPYING.
// If not, write to the Free Software Foundation, Inc.,
// 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// DDD is the data display debugger.
// For details, see the DDD World-Wide-Web page,
// `http://www.cs.tu-bs.de/softech/ddd/',
// or send a mail to the DDD developers <[e-mail]>.

char hostname_rcsid[] =
    "$Id: hostname.C,v 1.23 1998/11/16 13:41:26 zeller Exp $";

#include "hostname.h"
#include "config.h"
#include "bool.h"

#include <stdio.h>
#include <string.h>
#include <unistd.h>

#if !HAVE_POPEN_DECL
extern "C" FILE *popen(const char *command, const char *mode);
#endif
#if !HAVE_PCLOSE_DECL
extern "C" int pclose(FILE *stream);
#endif

extern "C" {
// Get hostname.
// We prefer gethostname() on uname() since <sys/utsname.h> makes
// trouble on some systems.
#if HAVE_GETHOSTNAME
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if !HAVE_GETHOSTNAME_DECL
    int gethostname(char *name, size_t size);
#endif // !HAVE_GETHOSTNAME_DECL
#elif HAVE_UNAME
#if HAVE_SYS_UTSNAME_H
#include <sys/utsname.h>
#endif
#if !HAVE_UNAME_DECL
    int uname(struct utsname *name);
#endif
#endif // HAVE_UNAME


// Get host aliases.
#if HAVE_GETHOSTBYNAME && HAVE_NETDB_H

#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif

#include <netdb.h>

#ifndef AF_INET
#define AF_INET 2        // internetwork: UDP, TCP, etc.
#endif

#endif // HAVE_GETHOSTBYNAME && HAVE_NETDB_H
}

#include <sys/param.h>
#ifndef MAXHOSTNAMELEN
#define MAXHOSTNAMELEN 1024
#endif

// Return the host name
char *hostname()
{
    static char *name = 0;
    if (name)
    return name;

    char buffer[MAXHOSTNAMELEN];

    bool okay = false;

#if HAVE_GETHOSTNAME
    if (!okay && gethostname(buffer, sizeof(buffer)) == 0)
    {
    okay = true;
    }
#elif HAVE_UNAME
    struct utsname un;
    if (!okay && uname(&un) >= 0)
    {
    strcpy(buffer, un.nodename);
    okay = true;
    }
#endif

    if (!okay)
    {
    FILE *fp = popen("uname -n", "r");
    if (fp != 0)
    {
        buffer[0] = '\0';
        fscanf(fp, "%s", buffer);
    }
    pclose(fp);
    }

    if (okay)
    return name = strcpy(new char[strlen(buffer) + 1], buffer);
    else
    return name = "unknown";
}

// Return the number of '.' in STR
inline int dots(const char *str)
{
    int dots = 0;
    while (*str != '\0')
    if (*str++ == '.')
        dots++;

    return dots;
}

// Return most qualified name for the current host
static char *_fullhostname(char *most_qualified_host)
{
    // Try local name
    if (most_qualified_host == 0)
    most_qualified_host = hostname();

#if HAVE_GETHOSTBYNAME
    struct hostent *h = gethostbyname(most_qualified_host);
    if (h)
    {
    // Try official name
    if (dots(h->h_name) > dots(most_qualified_host))
        most_qualified_host = (char *)h->h_name;

    // Try aliases
    for (int i = 0; h->h_aliases[i] != 0; i++)
        if (dots(h->h_aliases[i]) > dots(most_qualified_host))
        most_qualified_host = h->h_aliases[i];

    if (dots(most_qualified_host) == 0)
    {
        // Unqualified host - try network addresses
        if (h->h_addrtype == AF_INET)
        {
        for (int j = 0; h->h_addr_list[j] != 0; j++)
        {
            static char num_host[128];
            num_host[0] = '\0';
            for (int i = 0; i < h->h_length; i++)
            sprintf(num_host + strlen(num_host), i ? ".%d" : "%d",
                int((unsigned char)(h->h_addr_list[j][i])));

            if (dots(num_host) > dots(most_qualified_host))
            most_qualified_host = num_host;
        }
        }
    }
    }
#endif

    // Return most qualified host name
    return most_qualified_host;
}


// Return and cache a fully qualified name for the current host
char *fullhostname(char *host)
{
    // Buffer for local host name
    static char *name = 0;

    if (name && host == 0)
    return name;

    char *n = _fullhostname(host);
    if (host == 0)
    return name = strcpy(new char[strlen(n) + 1], n);
    else
    return n;
}