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Annotation of embedaddon/arping/src/findif_linux.c, revision 1.1.1.1

1.1       misho       1: /* arping/src/findif_linux.c
                      2:  *
                      3:  *  Copyright (C) 2000-2009 Thomas Habets <thomas@habets.pp.se>
                      4:  *
                      5:  *  This library is free software; you can redistribute it and/or
                      6:  *  modify it under the terms of the GNU General Public
                      7:  *  License as published by the Free Software Foundation; either
                      8:  *  version 2 of the License, or (at your option) any later version.
                      9:  *
                     10:  *  This library 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 GNU
                     13:  *  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: #if HAVE_CONFIG_H
                     20: #include "config.h"
                     21: #endif
                     22: 
                     23: #include <stdio.h>
                     24: #include <string.h>
                     25: 
                     26: #include "arping.h"
                     27: 
                     28: /**
                     29:  * WARNING: non-reentrant
                     30:  */
                     31: const char *
                     32: arping_lookupdev(const char *ifname,
                     33:                  uint32_t srcip,
                     34:                  uint32_t dstip,
                     35:                  char *ebuf)
                     36: {
                     37:        FILE *f;
                     38:        static char buf[1024];
                     39:        char buf1[1024];
                     40:        char buf2[1024];
                     41:        char *p,*p2;
                     42:        int n;
                     43: 
                     44:        do_libnet_init(ifname);
                     45:        libnet_addr2name4_r(dstip,0,buf2,1024);
                     46:        libnet_addr2name4_r(srcip,0,buf1,1024);
                     47: 
                     48:        /*
                     49:         * Construct and run command
                     50:         */
                     51:        snprintf(buf, 1023, "/sbin/ip route get %s from %s 2>&1",
                     52:                 buf2, buf1);
                     53:        if (!(f = popen(buf, "r"))) {
                     54:                goto failed;
                     55:        }
                     56:        if (0>(n = fread(buf, 1, sizeof(buf)-1, f))) {
                     57:                pclose(f);
                     58:                goto failed;
                     59:        }
                     60:        buf[n] = 0;
                     61:        if (-1 == pclose(f)) {
                     62:                perror("arping: pclose()");
                     63:                goto failed;
                     64:        }
                     65: 
                     66:        /*
                     67:         * Parse interface name
                     68:         */
                     69:        p = strstr(buf, "dev ");
                     70:        if (!p) {
                     71:                goto failed;
                     72:        }
                     73: 
                     74:        p+=4;
                     75: 
                     76:        p2 = strchr(p, ' ');
                     77:        if (!p2) {
                     78:                goto failed;
                     79:        }
                     80:        *p2 = 0;
                     81:        return p;
                     82:  failed:
                     83:        return arping_lookupdev_default(ifname,srcip,dstip,ebuf);
                     84: }