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arping v2.15

    1: /* arping/src/findif_bsdroute.c
    2:  *
    3:  *  Copyright (C) 2000-2014 Thomas Habets <thomas@habets.se>
    4:  *
    5:  *  This program is free software; you can redistribute it and/or modify
    6:  *  it under the terms of the GNU General Public License as published by
    7:  *  the Free Software Foundation; either version 2 of the License, or
    8:  *  (at your option) any later version.
    9:  *
   10:  *  This program is distributed in the hope that it will be useful,
   11:  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   12:  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   13:  *  GNU General Public License for more details.
   14:  *
   15:  *  You should have received a copy of the GNU General Public License along
   16:  *  with this program; if not, write to the Free Software Foundation, Inc.,
   17:  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   18:  */
   19: /**
   20:  * Fallback to ugly solution. This should not actually be used, as
   21:  * modern systems have getifaddrs().
   22:  */
   23: #if HAVE_CONFIG_H
   24: #include "config.h"
   25: #endif
   26: 
   27: #include <stdio.h>
   28: #include <string.h>
   29: 
   30: #if HAVE_LIBNET_H
   31: #include <libnet.h>
   32: #endif
   33: 
   34: #include "arping.h"
   35: 
   36: /**
   37:  *
   38:  */
   39: const char *
   40: arping_lookupdev(uint32_t srcip,
   41:                  uint32_t dstip,
   42:                  char *ebuf)
   43: {
   44:         FILE *f = NULL;
   45: 	static char buf[10240];
   46: 	char buf1[1024];
   47: 	char *p,*p2;
   48: 	int n;
   49: 
   50:         *ebuf = 0;
   51: 
   52:         do_libnet_init(NULL, 0);
   53: 	libnet_addr2name4_r(dstip,0,buf1, 1024);
   54: 
   55: 	/*
   56: 	 * Construct and run command
   57: 	 */
   58: 	snprintf(buf, 1023, "/sbin/route -n get %s 2>&1",
   59: 		 buf1);
   60: 	if (!(f = popen(buf, "r"))) {
   61:                 snprintf(ebuf, LIBNET_ERRBUF_SIZE,
   62:                          "popen(/sbin/route): %s", strerror(errno));
   63: 		goto failed;
   64: 	}
   65: 	if (0 > (n = fread(buf, 1, sizeof(buf)-1, f))) {
   66:                 snprintf(ebuf, LIBNET_ERRBUF_SIZE,
   67:                          "fread(/sbin/route): %s", strerror(errno));
   68: 		goto failed;
   69: 	}
   70: 	buf[n] = 0;
   71: 	if (-1 == pclose(f)) {
   72:                 snprintf(ebuf, LIBNET_ERRBUF_SIZE,
   73:                          "pclose(/sbin/route): %s", strerror(errno));
   74: 		goto failed;
   75: 	}
   76:         f = NULL;
   77: 
   78: 	/*
   79: 	 * Parse interface name
   80: 	 */
   81:         const char* head = "interface: ";
   82:         p = strstr(buf, head);
   83: 	if (!p) {
   84:                 if (verbose) {
   85:                         printf("arping: /sbin/route output: %s\n", buf);
   86:                 }
   87:                 snprintf(ebuf, LIBNET_ERRBUF_SIZE,
   88:                          "\"interface:\" not found in /sbin/route output.");
   89: 		goto failed;
   90: 	}
   91: 
   92:         p += strlen(head);
   93: 
   94: 	p2 = strchr(p, '\n');
   95: 	if (!p2) {
   96:                 if (verbose) {
   97:                         printf("arping: /sbin/route output: %s\n", buf);
   98:                 }
   99:                 snprintf(ebuf, LIBNET_ERRBUF_SIZE,
  100:                          "interface not found in /sbin/route output.");
  101: 		goto failed;
  102: 	}
  103: 	*p2 = 0;
  104: 	return p;
  105:  failed:
  106:         if (f) {
  107:                 pclose(f);
  108:         }
  109: 	return NULL;
  110: }
  111: /* ---- Emacs Variables ----
  112:  * Local Variables:
  113:  * c-basic-offset: 8
  114:  * indent-tabs-mode: nil
  115:  * End:
  116:  */