lib/libc/rpc/get_myaddress.c

   1 /*
   2  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
   3  * unrestricted use provided that this legend is included on all tape
   4  * media and as a part of the software program in whole or part.  Users
   5  * may copy or modify Sun RPC without charge, but are not authorized
   6  * to license or distribute it to anyone else except as part of a product or
   7  * program developed by the user.
   8  *
   9  * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
  10  * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
  11  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
  12  *
  13  * Sun RPC is provided with no support and without any obligation on the
  14  * part of Sun Microsystems, Inc. to assist in its use, correction,
  15  * modification or enhancement.
  16  *
  17  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
  18  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
  19  * OR ANY PART THEREOF.
  20  *
  21  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
  22  * or profits or other special, indirect and consequential damages, even if
  23  * Sun has been advised of the possibility of such damages.
  24  *
  25  * Sun Microsystems, Inc.
  26  * 2550 Garcia Avenue
  27  * Mountain View, California  94043
  28  *
  29  * @(#)get_myaddress.c 1.4 87/08/11 Copyr 1984 Sun Micro
  30  * @(#)get_myaddress.c  2.1 88/07/29 4.0 RPCSRC
  31  * $FreeBSD: src/lib/libc/rpc/get_myaddress.c,v 1.18.2.1 2003/01/01 23:55:34 jdp Exp $
  32  * $DragonFly: src/lib/libc/rpc/get_myaddress.c,v 1.5 2007/11/25 01:28:22 swildner Exp $
  33  */
  34
  35 /*
  36  * get_myaddress.c
  37  *
  38  * Get client's IP address via ioctl.  This avoids using the yellowpages.
  39  * Copyright (C) 1984, Sun Microsystems, Inc.
  40  */
  41
  42 #include "namespace.h"
  43 #include <rpc/types.h>
  44 #include <rpc/xdr.h>
  45 #include <rpc/pmap_prot.h>
  46 #include <sys/socket.h>
  47 #include <stdio.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50 #include <net/if.h>
  51 #include <sys/ioctl.h>
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54 #include "un-namespace.h"
  55
  56 /*
  57  * don't use gethostbyname, which would invoke yellow pages
  58  *
  59  * Avoid loopback interfaces.  We return information from a loopback
  60  * interface only if there are no other possible interfaces.
  61  */
  62 int
  63 get_myaddress(struct sockaddr_in *addr)
  64 {
  65         int s;
  66         char buf[BUFSIZ];
  67         struct ifconf ifc;
  68         struct ifreq ifreq, *ifr, *end;
  69         int loopback = 0, gotit = 0;
  70
  71         if ((s = _socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
  72                 return(-1);
  73         }
  74         ifc.ifc_len = sizeof (buf);
  75         ifc.ifc_buf = buf;
  76         if (_ioctl(s, SIOCGIFCONF, (char *)&ifc) < 0) {
  77                 _close(s);
  78                 return(-1);
  79         }
  80 again:
  81         ifr = ifc.ifc_req;
  82         end = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len);
  83
  84         while (ifr < end) {
  85                 memcpy(&ifreq, ifr, sizeof(ifreq));
  86                 if (_ioctl(s, SIOCGIFFLAGS, (char *)&ifreq) < 0) {
  87                         _close(s);
  88                         return(-1);
  89                 }
  90                 if (((ifreq.ifr_flags & IFF_UP) &&
  91                     ifr->ifr_addr.sa_family == AF_INET &&
  92                         !(ifreq.ifr_flags & IFF_LOOPBACK) &&
  93                         ((struct sockaddr_in *)&ifr->ifr_addr)->sin_addr.s_addr
  94                         != 0) ||
  95                     (loopback == 1 && (ifreq.ifr_flags & IFF_LOOPBACK)
  96                         && (ifr->ifr_addr.sa_family == AF_INET)
  97                         && (ifreq.ifr_flags &  IFF_UP))) {
  98                         *addr = *((struct sockaddr_in *)&ifr->ifr_addr);
  99                         addr->sin_port = htons(PMAPPORT);
 100                         gotit = 1;
 101                         break;
 102                 }
 103                 if (ifr->ifr_addr.sa_len)
 104                         ifr = (struct ifreq *) ((caddr_t) ifr +
 105                               ifr->ifr_addr.sa_len -
 106                               sizeof(struct sockaddr));
 107                 ifr++;
 108         }
 109         if (gotit == 0 && loopback == 0) {
 110                 loopback = 1;
 111                 goto again;
 112         }
 113         _close(s);
 114         return (gotit ? 0 : -1);
 115 }