summaryrefslogtreecommitdiffstats
blob: 913f51e815fb60d261dd30d9ef7e953c3d8ae66f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
/*
 * Copyright 2008, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 *
 *     http://www.apache.org/licenses/LICENSE-2.0 
 *
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 */

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

#include <sys/socket.h>
#include <sys/select.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <netdb.h>

#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/netlink.h>
#include <linux/route.h>
#include <linux/ipv6_route.h>
#include <linux/rtnetlink.h>
#include <linux/sockios.h>

#include "netutils/ifc.h"

#ifdef ANDROID
#define LOG_TAG "NetUtils"
#include <cutils/log.h>
#include <cutils/properties.h>
#else
#include <stdio.h>
#include <string.h>
#define ALOGD printf
#define ALOGW printf
#endif

#ifdef HAVE_ANDROID_OS
/* SIOCKILLADDR is an Android extension. */
#define SIOCKILLADDR 0x8939
#endif

static int ifc_ctl_sock = -1;
static int ifc_ctl_sock6 = -1;
void printerr(char *fmt, ...);

#define DBG 0
#define INET_ADDRLEN 4
#define INET6_ADDRLEN 16

in_addr_t prefixLengthToIpv4Netmask(int prefix_length)
{
    in_addr_t mask = 0;

    // C99 (6.5.7): shifts of 32 bits have undefined results
    if (prefix_length <= 0 || prefix_length > 32) {
        return 0;
    }

    mask = ~mask << (32 - prefix_length);
    mask = htonl(mask);

    return mask;
}

int ipv4NetmaskToPrefixLength(in_addr_t mask)
{
    int prefixLength = 0;
    uint32_t m = (uint32_t)ntohl(mask);
    while (m & 0x80000000) {
        prefixLength++;
        m = m << 1;
    }
    return prefixLength;
}

static const char *ipaddr_to_string(in_addr_t addr)
{
    struct in_addr in_addr;

    in_addr.s_addr = addr;
    return inet_ntoa(in_addr);
}

int string_to_ip(const char *string, struct sockaddr_storage *ss) {
    struct addrinfo hints, *ai;
    int ret;

    if (ss == NULL) {
        return -EFAULT;
    }

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_flags = AI_NUMERICHOST;
    hints.ai_socktype = SOCK_DGRAM;

    ret = getaddrinfo(string, NULL, &hints, &ai);
    if (ret == 0) {
        memcpy(ss, ai->ai_addr, ai->ai_addrlen);
        freeaddrinfo(ai);
    }

    return ret;
}

int ifc_init(void)
{
    int ret;
    if (ifc_ctl_sock == -1) {
        ifc_ctl_sock = socket(AF_INET, SOCK_DGRAM, 0);
        if (ifc_ctl_sock < 0) {
            printerr("socket() failed: %s\n", strerror(errno));
        }
    }

    ret = ifc_ctl_sock < 0 ? -1 : 0;
    if (DBG) printerr("ifc_init_returning %d", ret);
    return ret;
}

int ifc_init6(void)
{
    if (ifc_ctl_sock6 == -1) {
        ifc_ctl_sock6 = socket(AF_INET6, SOCK_DGRAM, 0);
        if (ifc_ctl_sock6 < 0) {
            printerr("socket() failed: %s\n", strerror(errno));
        }
    }
    return ifc_ctl_sock6 < 0 ? -1 : 0;
}

void ifc_close(void)
{
    if (DBG) printerr("ifc_close");
    if (ifc_ctl_sock != -1) {
        (void)close(ifc_ctl_sock);
        ifc_ctl_sock = -1;
    }
}

void ifc_close6(void)
{
    if (ifc_ctl_sock6 != -1) {
        (void)close(ifc_ctl_sock6);
        ifc_ctl_sock6 = -1;
    }
}

static void ifc_init_ifr(const char *name, struct ifreq *ifr)
{
    memset(ifr, 0, sizeof(struct ifreq));
    strncpy(ifr->ifr_name, name, IFNAMSIZ);
    ifr->ifr_name[IFNAMSIZ - 1] = 0;
}

int ifc_get_hwaddr(const char *name, void *ptr)
{
    int r;
    struct ifreq ifr;
    ifc_init_ifr(name, &ifr);

    r = ioctl(ifc_ctl_sock, SIOCGIFHWADDR, &ifr);
    if(r < 0) return -1;

    memcpy(ptr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
    return 0;
}

int ifc_get_ifindex(const char *name, int *if_indexp)
{
    int r;
    struct ifreq ifr;
    ifc_init_ifr(name, &ifr);

    r = ioctl(ifc_ctl_sock, SIOCGIFINDEX, &ifr);
    if(r < 0) return -1;

    *if_indexp = ifr.ifr_ifindex;
    return 0;
}

static int ifc_set_flags(const char *name, unsigned set, unsigned clr)
{
    struct ifreq ifr;
    ifc_init_ifr(name, &ifr);

    if(ioctl(ifc_ctl_sock, SIOCGIFFLAGS, &ifr) < 0) return -1;
    ifr.ifr_flags = (ifr.ifr_flags & (~clr)) | set;
    return ioctl(ifc_ctl_sock, SIOCSIFFLAGS, &ifr);
}

int ifc_up(const char *name)
{
    int ret = ifc_set_flags(name, IFF_UP, 0);
    if (DBG) printerr("ifc_up(%s) = %d", name, ret);
    return ret;
}

int ifc_down(const char *name)
{
    int ret = ifc_set_flags(name, 0, IFF_UP);
    if (DBG) printerr("ifc_down(%s) = %d", name, ret);
    return ret;
}

static void init_sockaddr_in(struct sockaddr *sa, in_addr_t addr)
{
    struct sockaddr_in *sin = (struct sockaddr_in *) sa;
    sin->sin_family = AF_INET;
    sin->sin_port = 0;
    sin->sin_addr.s_addr = addr;
}

int ifc_set_addr(const char *name, in_addr_t addr)
{
    struct ifreq ifr;
    int ret;

    ifc_init_ifr(name, &ifr);
    init_sockaddr_in(&ifr.ifr_addr, addr);

    ret = ioctl(ifc_ctl_sock, SIOCSIFADDR, &ifr);
    if (DBG) printerr("ifc_set_addr(%s, xx) = %d", name, ret);
    return ret;
}

/*
 * Adds or deletes an IP address on an interface.
 *
 * Action is one of:
 * - RTM_NEWADDR (to add a new address)
 * - RTM_DELADDR (to delete an existing address)
 *
 * Returns zero on success and negative errno on failure.
 */
int ifc_act_on_address(int action, const char *name, const char *address,
                       int prefixlen) {
    int ifindex, s, len, ret;
    struct sockaddr_storage ss;
    void *addr;
    size_t addrlen;
    struct {
        struct nlmsghdr n;
        struct ifaddrmsg r;
        // Allow for IPv6 address, headers, and padding.
        char attrbuf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
                     NLMSG_ALIGN(sizeof(struct rtattr)) +
                     NLMSG_ALIGN(INET6_ADDRLEN)];
    } req;
    struct rtattr *rta;
    struct nlmsghdr *nh;
    struct nlmsgerr *err;
    char buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
             NLMSG_ALIGN(sizeof(struct nlmsgerr)) +
             NLMSG_ALIGN(sizeof(struct nlmsghdr))];

    // Get interface ID.
    ifindex = if_nametoindex(name);
    if (ifindex == 0) {
        return -errno;
    }

    // Convert string representation to sockaddr_storage.
    ret = string_to_ip(address, &ss);
    if (ret) {
        return ret;
    }

    // Determine address type and length.
    if (ss.ss_family == AF_INET) {
        struct sockaddr_in *sin = (struct sockaddr_in *) &ss;
        addr = &sin->sin_addr;
        addrlen = INET_ADDRLEN;
    } else if (ss.ss_family == AF_INET6) {
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &ss;
        addr = &sin6->sin6_addr;
        addrlen = INET6_ADDRLEN;
    } else {
        return -EAFNOSUPPORT;
    }

    // Fill in netlink structures.
    memset(&req, 0, sizeof(req));

    // Netlink message header.
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.r));
    req.n.nlmsg_type = action;
    req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
    req.n.nlmsg_pid = getpid();

    // Interface address message header.
    req.r.ifa_family = ss.ss_family;
    req.r.ifa_prefixlen = prefixlen;
    req.r.ifa_index = ifindex;

    // Routing attribute. Contains the actual IP address.
    rta = (struct rtattr *) (((char *) &req) + NLMSG_ALIGN(req.n.nlmsg_len));
    rta->rta_type = IFA_LOCAL;
    rta->rta_len = RTA_LENGTH(addrlen);
    req.n.nlmsg_len = NLMSG_ALIGN(req.n.nlmsg_len) + RTA_LENGTH(addrlen);
    memcpy(RTA_DATA(rta), addr, addrlen);

    s = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
    if (send(s, &req, req.n.nlmsg_len, 0) < 0) {
        close(s);
        return -errno;
    }

    len = recv(s, buf, sizeof(buf), 0);
    close(s);
    if (len < 0) {
        return -errno;
    }

    // Parse the acknowledgement to find the return code.
    nh = (struct nlmsghdr *) buf;
    if (!NLMSG_OK(nh, (unsigned) len) || nh->nlmsg_type != NLMSG_ERROR) {
        return -EINVAL;
    }
    err = NLMSG_DATA(nh);

    // Return code is negative errno.
    return err->error;
}

int ifc_add_address(const char *name, const char *address, int prefixlen) {
    return ifc_act_on_address(RTM_NEWADDR, name, address, prefixlen);
}

int ifc_del_address(const char *name, const char * address, int prefixlen) {
    return ifc_act_on_address(RTM_DELADDR, name, address, prefixlen);
}

/*
 * Clears IPv6 addresses on the specified interface.
 */
int ifc_clear_ipv6_addresses(const char *name) {
    char rawaddrstr[INET6_ADDRSTRLEN], addrstr[INET6_ADDRSTRLEN];
    unsigned int prefixlen;
    int lasterror = 0, i, j, ret;
    char ifname[64];  // Currently, IFNAMSIZ = 16.
    FILE *f = fopen("/proc/net/if_inet6", "r");
    if (!f) {
        return -errno;
    }

    // Format:
    // 20010db8000a0001fc446aa4b5b347ed 03 40 00 01    wlan0
    while (fscanf(f, "%32s %*02x %02x %*02x %*02x %63s\n",
                  rawaddrstr, &prefixlen, ifname) == 3) {
        // Is this the interface we're looking for?
        if (strcmp(name, ifname)) {
            continue;
        }

        // Put the colons back into the address.
        for (i = 0, j = 0; i < 32; i++, j++) {
            addrstr[j] = rawaddrstr[i];
            if (i % 4 == 3) {
                addrstr[++j] = ':';
            }
        }
        addrstr[j - 1] = '\0';

        // Don't delete the link-local address as well, or it will disable IPv6
        // on the interface.
        if (strncmp(addrstr, "fe80:", 5) == 0) {
            continue;
        }

        ret = ifc_del_address(ifname, addrstr, prefixlen);
        if (ret) {
            ALOGE("Deleting address %s/%d on %s: %s", addrstr, prefixlen, ifname,
                 strerror(-ret));
            lasterror = ret;
        }
    }

    fclose(f);
    return lasterror;
}

/*
 * Clears IPv4 addresses on the specified interface.
 */
void ifc_clear_ipv4_addresses(const char *name) {
    unsigned count, addr;
    ifc_init();
    for (count=0, addr=1;((addr != 0) && (count < 255)); count++) {
        if (ifc_get_addr(name, &addr) < 0)
            break;
        if (addr)
            ifc_set_addr(name, 0);
    }
    ifc_close();
}

/*
 * Clears all IP addresses on the specified interface.
 */
int ifc_clear_addresses(const char *name) {
    ifc_clear_ipv4_addresses(name);
    return ifc_clear_ipv6_addresses(name);
}

int ifc_set_hwaddr(const char *name, const void *ptr)
{
    int r;
    struct ifreq ifr;
    ifc_init_ifr(name, &ifr);

    ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;
    memcpy(&ifr.ifr_hwaddr.sa_data, ptr, ETH_ALEN);
    return ioctl(ifc_ctl_sock, SIOCSIFHWADDR, &ifr);
}

int ifc_set_mask(const char *name, in_addr_t mask)
{
    struct ifreq ifr;
    int ret;

    ifc_init_ifr(name, &ifr);
    init_sockaddr_in(&ifr.ifr_addr, mask);

    ret = ioctl(ifc_ctl_sock, SIOCSIFNETMASK, &ifr);
    if (DBG) printerr("ifc_set_mask(%s, xx) = %d", name, ret);
    return ret;
}

int ifc_set_prefixLength(const char *name, int prefixLength)
{
    struct ifreq ifr;
    // TODO - support ipv6
    if (prefixLength > 32 || prefixLength < 0) return -1;

    in_addr_t mask = prefixLengthToIpv4Netmask(prefixLength);
    ifc_init_ifr(name, &ifr);
    init_sockaddr_in(&ifr.ifr_addr, mask);

    return ioctl(ifc_ctl_sock, SIOCSIFNETMASK, &ifr);
}

int ifc_get_addr(const char *name, in_addr_t *addr)
{
    struct ifreq ifr;
    int ret = 0;

    ifc_init_ifr(name, &ifr);
    if (addr != NULL) {
        ret = ioctl(ifc_ctl_sock, SIOCGIFADDR, &ifr);
        if (ret < 0) {
            *addr = 0;
        } else {
            *addr = ((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr;
        }
    }
    return ret;
}

int ifc_get_info(const char *name, in_addr_t *addr, int *prefixLength, unsigned *flags)
{
    struct ifreq ifr;
    ifc_init_ifr(name, &ifr);

    if (addr != NULL) {
        if(ioctl(ifc_ctl_sock, SIOCGIFADDR, &ifr) < 0) {
            *addr = 0;
        } else {
            *addr = ((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr;
        }
    }

    if (prefixLength != NULL) {
        if(ioctl(ifc_ctl_sock, SIOCGIFNETMASK, &ifr) < 0) {
            *prefixLength = 0;
        } else {
            *prefixLength = ipv4NetmaskToPrefixLength(
                    ((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr);
        }
    }

    if (flags != NULL) {
        if(ioctl(ifc_ctl_sock, SIOCGIFFLAGS, &ifr) < 0) {
            *flags = 0;
        } else {
            *flags = ifr.ifr_flags;
        }
    }

    return 0;
}

int ifc_act_on_ipv4_route(int action, const char *ifname, struct in_addr dst, int prefix_length,
      struct in_addr gw)
{
    struct rtentry rt;
    int result;
    in_addr_t netmask;

    memset(&rt, 0, sizeof(rt));

    rt.rt_dst.sa_family = AF_INET;
    rt.rt_dev = (void*) ifname;

    netmask = prefixLengthToIpv4Netmask(prefix_length);
    init_sockaddr_in(&rt.rt_genmask, netmask);
    init_sockaddr_in(&rt.rt_dst, dst.s_addr);
    rt.rt_flags = RTF_UP;

    if (prefix_length == 32) {
        rt.rt_flags |= RTF_HOST;
    }

    if (gw.s_addr != 0) {
        rt.rt_flags |= RTF_GATEWAY;
        init_sockaddr_in(&rt.rt_gateway, gw.s_addr);
    }

    ifc_init();

    if (ifc_ctl_sock < 0) {
        return -errno;
    }

    result = ioctl(ifc_ctl_sock, action, &rt);
    if (result < 0) {
        if (errno == EEXIST) {
            result = 0;
        } else {
            result = -errno;
        }
    }
    ifc_close();
    return result;
}

/* deprecated - v4 only */
int ifc_create_default_route(const char *name, in_addr_t gw)
{
    struct in_addr in_dst, in_gw;

    in_dst.s_addr = 0;
    in_gw.s_addr = gw;

    int ret = ifc_act_on_ipv4_route(SIOCADDRT, name, in_dst, 0, in_gw);
    if (DBG) printerr("ifc_create_default_route(%s, %d) = %d", name, gw, ret);
    return ret;
}

// Needed by code in hidden partner repositories / branches, so don't delete.
int ifc_enable(const char *ifname)
{
    int result;

    ifc_init();
    result = ifc_up(ifname);
    ifc_close();
    return result;
}

// Needed by code in hidden partner repositories / branches, so don't delete.
int ifc_disable(const char *ifname)
{
    unsigned addr, count;
    int result;

    ifc_init();
    result = ifc_down(ifname);

    ifc_set_addr(ifname, 0);
    for (count=0, addr=1;((addr != 0) && (count < 255)); count++) {
       if (ifc_get_addr(ifname, &addr) < 0)
            break;
       if (addr)
          ifc_set_addr(ifname, 0);
    }

    ifc_close();
    return result;
}

int ifc_reset_connections(const char *ifname, const int reset_mask)
{
#ifdef HAVE_ANDROID_OS
    int result, success;
    in_addr_t myaddr = 0;
    struct ifreq ifr;
    struct in6_ifreq ifr6;

    if (reset_mask & RESET_IPV4_ADDRESSES) {
        /* IPv4. Clear connections on the IP address. */
        ifc_init();
        if (!(reset_mask & RESET_IGNORE_INTERFACE_ADDRESS)) {
            ifc_get_info(ifname, &myaddr, NULL, NULL);
        }
        ifc_init_ifr(ifname, &ifr);
        init_sockaddr_in(&ifr.ifr_addr, myaddr);
        result = ioctl(ifc_ctl_sock, SIOCKILLADDR,  &ifr);
        ifc_close();
    } else {
        result = 0;
    }

    if (reset_mask & RESET_IPV6_ADDRESSES) {
        /*
         * IPv6. On Linux, when an interface goes down it loses all its IPv6
         * addresses, so we don't know which connections belonged to that interface
         * So we clear all unused IPv6 connections on the device by specifying an
         * empty IPv6 address.
         */
        ifc_init6();
        // This implicitly specifies an address of ::, i.e., kill all IPv6 sockets.
        memset(&ifr6, 0, sizeof(ifr6));
        success = ioctl(ifc_ctl_sock6, SIOCKILLADDR,  &ifr6);
        if (result == 0) {
            result = success;
        }
        ifc_close6();
    }

    return result;
#else
    return 0;
#endif
}

/*
 * Removes the default route for the named interface.
 */
int ifc_remove_default_route(const char *ifname)
{
    struct rtentry rt;
    int result;

    ifc_init();
    memset(&rt, 0, sizeof(rt));
    rt.rt_dev = (void *)ifname;
    rt.rt_flags = RTF_UP|RTF_GATEWAY;
    init_sockaddr_in(&rt.rt_dst, 0);
    if ((result = ioctl(ifc_ctl_sock, SIOCDELRT, &rt)) < 0) {
        ALOGD("failed to remove default route for %s: %s", ifname, strerror(errno));
    }
    ifc_close();
    return result;
}

int
ifc_configure(const char *ifname,
        in_addr_t address,
        uint32_t prefixLength,
        in_addr_t gateway,
        in_addr_t dns1,
        in_addr_t dns2) {

    char dns_prop_name[PROPERTY_KEY_MAX];

    ifc_init();

    if (ifc_up(ifname)) {
        printerr("failed to turn on interface %s: %s\n", ifname, strerror(errno));
        ifc_close();
        return -1;
    }
    if (ifc_set_addr(ifname, address)) {
        printerr("failed to set ipaddr %s: %s\n", ipaddr_to_string(address), strerror(errno));
        ifc_close();
        return -1;
    }
    if (ifc_set_prefixLength(ifname, prefixLength)) {
        printerr("failed to set prefixLength %d: %s\n", prefixLength, strerror(errno));
        ifc_close();
        return -1;
    }
    if (ifc_create_default_route(ifname, gateway)) {
        printerr("failed to set default route %s: %s\n", ipaddr_to_string(gateway), strerror(errno));
        ifc_close();
        return -1;
    }

    ifc_close();

    snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns1", ifname);
    property_set(dns_prop_name, dns1 ? ipaddr_to_string(dns1) : "");
    snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns2", ifname);
    property_set(dns_prop_name, dns2 ? ipaddr_to_string(dns2) : "");

    return 0;
}