summaryrefslogtreecommitdiffstats
path: root/proto/bgp/packets.c
blob: 3bddbc902ccece04dd4e3937db89094e4e09410e (plain)
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
/*
 *	BIRD -- BGP Packet Processing
 *
 *	(c) 2000 Martin Mares <mj@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#define LOCAL_DEBUG

#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "conf/conf.h"
#include "lib/unaligned.h"
#include "lib/socket.h"

#include "bgp.h"

static byte *
bgp_create_notification(struct bgp_conn *conn, byte *buf)
{
  DBG("BGP: Sending notification: code=%d, sub=%d, arg=%d:%d\n", conn->notify_code, conn->notify_subcode, conn->notify_arg, conn->notify_arg_size);
  buf[0] = conn->notify_code;
  buf[1] = conn->notify_subcode;
  switch (conn->notify_arg_size)
    {
    case 0:	return buf + 1;
    case 1:	buf[2] = conn->notify_arg; return buf+3;
    case 2:	put_u16(buf+2, conn->notify_arg); return buf+4;
    case 4:	put_u32(buf+2, conn->notify_arg); return buf+6;
    default:	bug("bgp_create_notification: unknown error code size");
    }
}

static byte *
bgp_create_open(struct bgp_conn *conn, byte *buf)
{
  DBG("BGP: Sending open\n");
  buf[0] = BGP_VERSION;
  put_u16(buf+1, conn->bgp->local_as);
  put_u16(buf+3, conn->bgp->cf->hold_time);
  put_u32(buf+5, conn->bgp->local_id);
  buf[9] = 0;				/* No optional parameters */
  return buf+10;
}

static byte *
bgp_create_update(struct bgp_conn *conn, byte *buf)
{
  DBG("BGP: Sending update\n");

  bug("Don't know how to create updates");
}

static void
bgp_create_header(byte *buf, unsigned int len, unsigned int type)
{
  memset(buf, 0xff, 16);		/* Marker */
  put_u16(buf+16, len);
  buf[18] = type;
}

static int
bgp_fire_tx(struct bgp_conn *conn)
{
  unsigned int s = conn->packets_to_send;
  sock *sk = conn->sk;
  byte *buf = sk->tbuf;
  byte *pkt = buf + BGP_HEADER_LENGTH;
  byte *end;
  int type;

  if (s & (1 << PKT_SCHEDULE_CLOSE))
    {
      bgp_close_conn(conn);
      return 0;
    }
  if (s & (1 << PKT_NOTIFICATION))
    {
      s = 1 << PKT_SCHEDULE_CLOSE;
      type = PKT_NOTIFICATION;
      end = bgp_create_notification(conn, pkt);
    }
  else if (s & (1 << PKT_KEEPALIVE))
    {
      s &= ~(1 << PKT_KEEPALIVE);
      type = PKT_KEEPALIVE;
      end = pkt;			/* Keepalives carry no data */
      DBG("BGP: Sending keepalive\n");
      bgp_start_timer(conn->keepalive_timer, conn->keepalive_time);
    }
  else if (s & (1 << PKT_OPEN))
    {
      s &= ~(1 << PKT_OPEN);
      type = PKT_OPEN;
      end = bgp_create_open(conn, pkt);
    }
  else if (s & (1 << PKT_UPDATE))
    {
      end = bgp_create_update(conn, pkt);
      type = PKT_UPDATE;
      if (!end)
	{
	  conn->packets_to_send = 0;
	  return 0;
	}
    }
  else
    return 0;
  conn->packets_to_send = s;
  bgp_create_header(buf, end - buf, type);
  return sk_send(sk, end - buf);
}

void
bgp_schedule_packet(struct bgp_conn *conn, int type)
{
  DBG("BGP: Scheduling packet type %d\n", type);
  conn->packets_to_send |= 1 << type;
  if (conn->sk->tpos == conn->sk->tbuf)
    while (bgp_fire_tx(conn))
      ;
}

void
bgp_tx(sock *sk)
{
  struct bgp_conn *conn = sk->data;

  DBG("BGP: TX hook\n");
  while (bgp_fire_tx(conn))
    ;
}

static void
bgp_rx_open(struct bgp_conn *conn, byte *pkt, int len)
{
  struct bgp_conn *other;
  struct bgp_proto *p = conn->bgp;
  struct bgp_config *cf = p->cf;
  unsigned as, hold;
  u32 id;

  /* Check state */
  if (conn->state != BS_OPENSENT)
    { bgp_error(conn, 5, 0, conn->state, 0); }

  /* Check message contents */
  if (len < 29 || len != 29 + pkt[28])
    { bgp_error(conn, 1, 2, len, 2); return; }
  if (pkt[19] != BGP_VERSION)
    { bgp_error(conn, 2, 1, pkt[19], 2); return; }
  as = get_u16(pkt+20);
  hold = get_u16(pkt+22);
  id = get_u32(pkt+24);
  DBG("BGP: OPEN as=%d hold=%d id=%08x\n", as, hold, id);
  if (cf->remote_as && as != p->remote_as)
    { bgp_error(conn, 2, 2, as, 0); return; }
  if (hold > 0 && hold < 3)
    { bgp_error(conn, 2, 6, hold, 0); return; }
  p->remote_id = id;
  if (pkt[28])				/* Currently we support no optional parameters */
    { bgp_error(conn, 2, 4, pkt[28], 0); return; }
  if (!id || id == 0xffffffff || id == p->local_id)
    { bgp_error(conn, 2, 3, id, 0); return; }

  /* Check the other connection */
  other = (conn == &p->outgoing_conn) ? &p->incoming_conn : &p->outgoing_conn;
  switch (other->state)
    {
    case BS_IDLE:
      break;
    case BS_CONNECT:
    case BS_ACTIVE:
    case BS_OPENSENT:
      DBG("BGP: Collision, closing the other connection\n");
      bgp_close_conn(other);
      break;
    case BS_OPENCONFIRM:
      if ((p->local_id < id) == (conn == &p->incoming_conn))
	{
	  /* Should close the other connection */
	  DBG("BGP: Collision, closing the other connection\n");
	  bgp_error(other, 6, 0, 0, 0);
	  break;
	}
      /* Fall thru */
    case BS_ESTABLISHED:
      /* Should close this connection */
      DBG("BGP: Collision, closing this connection\n");
      bgp_error(conn, 6, 0, 0, 0);
      return;
    default:
      bug("bgp_rx_open: Unknown state");
    }

  /* Make this connection primary */
  conn->primary = 1;
  p->conn = conn;

  /* Update our local variables */
  if (hold < p->cf->hold_time)
    conn->hold_time = hold;
  else
    conn->hold_time = p->cf->hold_time;
  conn->keepalive_time = p->cf->keepalive_time ? : conn->hold_time / 3;
  p->remote_as = as;
  p->remote_id = id;
  DBG("BGP: Hold timer set to %d, keepalive to %d, AS to %d, ID to %x\n", conn->hold_time, conn->keepalive_time, p->remote_as, p->remote_id);

  bgp_schedule_packet(conn, PKT_KEEPALIVE);
  bgp_start_timer(conn->hold_timer, conn->hold_time);
  conn->state = BS_OPENCONFIRM;
}

#define DECODE_PREFIX(pp, ll) do {		\
  int b = *pp++;				\
  int q;					\
  ip_addr temp;					\
  ll--;						\
  if (b > BITS_PER_IP_ADDRESS) { bgp_error(conn, 3, 10, b, 0); return; } \
  q = (b+7) / 8;				\
  if (ll < q) goto too_small;			\
  memcpy(&temp, pp, q);				\
  pp += q;					\
  ll -= q;					\
  n.n.prefix = ipa_and(ipa_ntoh(temp), ipa_mkmask(b));	\
  n.n.pxlen = b;				\
} while (0)

static void
bgp_rx_update(struct bgp_conn *conn, byte *pkt, int len)
{
  byte *withdrawn, *attrs, *nlri;
  int withdrawn_len, attr_len, nlri_len;
  net n;
  rte e;

  DBG("BGP: UPDATE\n");
  if (conn->state != BS_ESTABLISHED)
    { bgp_error(conn, 5, 0, conn->state, 0); return; }
  bgp_start_timer(conn->hold_timer, conn->hold_time);

  /* Find parts of the packet and check sizes */
  if (len < 23)
    {
    too_small:
      bgp_error(conn, 1, 2, len, 2);
      return;
    }
  withdrawn = pkt + 21;
  withdrawn_len = get_u16(pkt + 19);
  if (withdrawn_len + 23 > len)
    goto too_small;
  attrs = withdrawn + withdrawn_len + 2;
  attr_len = get_u16(attrs - 2);
  if (withdrawn_len + attr_len + 23 > len)
    goto too_small;
  nlri = attrs + attr_len;
  nlri_len = len - withdrawn_len - attr_len - 23;
  if (!attr_len && nlri_len)
    goto too_small;
  DBG("Sizes: withdrawn=%d, attrs=%d, NLRI=%d\n", withdrawn_len, attr_len, nlri_len);

  /* Withdraw routes */
  while (withdrawn_len)
    {
      DECODE_PREFIX(withdrawn, withdrawn_len);
      DBG("Withdraw %I/%d\n", n.n.prefix, n.n.pxlen);
    }

  if (nlri_len)
    {
#if 0
      rta *a = bgp_decode_attrs(conn, attrs, attr_len, bgp_linpool);
      if (a)
#endif
	{
	  while (nlri_len)
	    {
	      DECODE_PREFIX(nlri, nlri_len);
	      DBG("Add %I/%d\n", n.n.prefix, n.n.pxlen);
	    }
	}
      lp_flush(bgp_linpool);
    }
}

static void
bgp_rx_notification(struct bgp_conn *conn, byte *pkt, int len)
{
  unsigned arg;

  if (len < 21)
    {
      bgp_error(conn, 1, 2, len, 2);
      return;
    }
  switch (len)
    {
    case 21: arg = 0; break;
    case 22: arg = pkt[21]; break;
    case 23: arg = get_u16(pkt+21); break;
    case 25: arg = get_u32(pkt+23); break;
    default: DBG("BGP: NOTIFICATION with too much data\n"); /* FIXME */ arg = 0;
    }
  DBG("BGP: NOTIFICATION %d.%d %08x\n", pkt[19], pkt[20], arg);	/* FIXME: Better reporting */
  conn->error_flag = 1;
  if (conn->primary)
    proto_notify_state(&conn->bgp->p, PS_STOP);
  bgp_schedule_packet(conn, PKT_SCHEDULE_CLOSE);
}

static void
bgp_rx_keepalive(struct bgp_conn *conn, byte *pkt, unsigned len)
{
  DBG("BGP: KEEPALIVE\n");
  bgp_start_timer(conn->hold_timer, conn->hold_time);
  switch (conn->state)
    {
    case BS_OPENCONFIRM:
      DBG("BGP: UP!!!\n");
      conn->state = BS_ESTABLISHED;
      proto_notify_state(&conn->bgp->p, PS_UP);
      break;
    case BS_ESTABLISHED:
      break;
    default:
      bgp_error(conn, 5, 0, conn->state, 0);
    }
}

static void
bgp_rx_packet(struct bgp_conn *conn, byte *pkt, unsigned len)
{
  DBG("BGP: Got packet %02x (%d bytes)\n", pkt[18], len);
  switch (pkt[18])
    {
    case PKT_OPEN:		return bgp_rx_open(conn, pkt, len);
    case PKT_UPDATE:		return bgp_rx_update(conn, pkt, len);
    case PKT_NOTIFICATION:      return bgp_rx_notification(conn, pkt, len);
    case PKT_KEEPALIVE:		return bgp_rx_keepalive(conn, pkt, len);
    default:			bgp_error(conn, 1, 3, pkt[18], 1);
    }
}

int
bgp_rx(sock *sk, int size)
{
  struct bgp_conn *conn = sk->data;
  byte *pkt_start = sk->rbuf;
  byte *end = pkt_start + size;
  unsigned i, len;

  DBG("BGP: RX hook: Got %d bytes\n", size);
  while (end >= pkt_start + BGP_HEADER_LENGTH)
    {
      if (conn->error_flag)
	{
	  DBG("BGP: Error, dropping input\n");
	  return 1;
	}
      for(i=0; i<16; i++)
	if (pkt_start[i] != 0xff)
	  {
	    bgp_error(conn, 1, 1, 0, 0);
	    break;
	  }
      len = get_u16(pkt_start+16);
      if (len < BGP_HEADER_LENGTH || len > BGP_MAX_PACKET_LENGTH)
	{
	  bgp_error(conn, 1, 2, len, 2);
	  break;
	}
      if (end >= pkt_start + len)
	{
	  bgp_rx_packet(conn, pkt_start, len);
	  pkt_start += len;
	}
    }
  if (pkt_start != sk->rbuf)
    {
      memmove(sk->rbuf, pkt_start, end - pkt_start);
      sk->rpos = sk->rbuf + (end - pkt_start);
    }
  return 0;
}