summaryrefslogtreecommitdiff
path: root/lib/route-table.c
blob: 8e54b2848983727e12511f23a065f9150460df36 (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
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
/*
 * Copyright (c) 2011, 2012 Nicira Networks.
 *
 * 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 <config.h>

#include "route-table.h"

#include <assert.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <linux/rtnetlink.h>
#include <net/if.h>

#include "hash.h"
#include "hmap.h"
#include "netlink.h"
#include "netlink-notifier.h"
#include "netlink-socket.h"
#include "ofpbuf.h"
#include "rtnetlink-link.h"
#include "vlog.h"

VLOG_DEFINE_THIS_MODULE(route_table);

struct route_data {
    /* Copied from struct rtmsg. */
    unsigned char rtm_dst_len;

    /* Extracted from Netlink attributes. */
    uint32_t rta_dst; /* Destination in host byte order. 0 if missing. */
    int rta_oif;      /* Output interface index. */
};

/* A digested version of a route message sent down by the kernel to indicate
 * that a route has changed. */
struct route_table_msg {
    bool relevant;        /* Should this message be processed? */
    int nlmsg_type;       /* e.g. RTM_NEWROUTE, RTM_DELROUTE. */
    struct route_data rd; /* Data parsed from this message. */
};

struct route_node {
    struct hmap_node node; /* Node in route_map. */
    struct route_data rd;  /* Data associated with this node. */
};

struct name_node {
    struct hmap_node node; /* Node in name_map. */
    uint32_t ifi_index;    /* Kernel interface index. */

    char ifname[IFNAMSIZ]; /* Interface name. */
};

static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);

static unsigned int register_count = 0;
static struct nln *nln = NULL;
static struct route_table_msg rtmsg;
static struct nln_notifier *route_notifier = NULL;
static struct nln_notifier *name_notifier = NULL;

static bool route_table_valid = false;
static bool name_table_valid = false;
static struct hmap route_map;
static struct hmap name_map;

static int route_table_reset(void);
static void route_table_handle_msg(const struct route_table_msg *);
static bool route_table_parse(struct ofpbuf *, struct route_table_msg *);
static void route_table_change(const struct route_table_msg *, void *);
static struct route_node *route_node_lookup(const struct route_data *);
static struct route_node *route_node_lookup_by_ip(uint32_t ip);
static void route_map_clear(void);
static uint32_t hash_route_data(const struct route_data *);

static void name_table_init(void);
static void name_table_uninit(void);
static int name_table_reset(void);
static void name_table_change(const struct rtnetlink_link_change *, void *);
static void name_map_clear(void);
static struct name_node *name_node_lookup(int ifi_index);

/* Populates 'name' with the name of the interface traffic destined for 'ip'
 * is likely to egress out of (see route_table_get_ifindex).
 *
 * Returns true if successful, otherwise false. */
bool
route_table_get_name(ovs_be32 ip, char name[IFNAMSIZ])
{
    int ifindex;

    if (!name_table_valid) {
        name_table_reset();
    }

    if (route_table_get_ifindex(ip, &ifindex)) {
        struct name_node *nn;

        nn = name_node_lookup(ifindex);
        if (nn) {
            ovs_strlcpy(name, nn->ifname, IFNAMSIZ);
            return true;
        }
    }

    return false;
}

/* Populates 'ifindex' with the interface index traffic destined for 'ip' is
 * likely to egress.  There is no hard guarantee that traffic destined for 'ip'
 * will egress out the specified interface.  'ifindex' may refer to an
 * interface which is not physical (such as a bridge port).
 *
 * Returns true if successful, otherwise false. */
bool
route_table_get_ifindex(ovs_be32 ip_, int *ifindex)
{
    struct route_node *rn;
    uint32_t ip = ntohl(ip_);

    *ifindex = 0;

    if (!route_table_valid) {
        route_table_reset();
    }

    rn = route_node_lookup_by_ip(ip);

    if (rn) {
        *ifindex = rn->rd.rta_oif;
        return true;
    }

    /* Choose a default route. */
    HMAP_FOR_EACH(rn, node, &route_map) {
        if (rn->rd.rta_dst == 0 && rn->rd.rtm_dst_len == 0) {
            *ifindex = rn->rd.rta_oif;
            return true;
        }
    }

    return false;
}

/* Users of the route_table module should register themselves with this
 * function before making any other route_table function calls. */
void
route_table_register(void)
{
    if (!register_count) {
        assert(!nln);
        assert(!route_notifier);

        nln = nln_create(NETLINK_ROUTE, RTNLGRP_IPV4_ROUTE,
                         (nln_parse_func *) route_table_parse, &rtmsg);

        route_notifier =
            nln_notifier_create(nln, (nln_notify_func *) route_table_change,
                                NULL);

        hmap_init(&route_map);
        route_table_reset();
        name_table_init();
    }

    register_count++;
}

/* Users of the route_table module should unregister themselves with this
 * function when they will no longer be making any more route_table fuction
 * calls. */
void
route_table_unregister(void)
{
    register_count--;

    if (!register_count) {
        nln_notifier_destroy(route_notifier);
        route_notifier = NULL;
        nln_destroy(nln);
        nln = NULL;

        route_map_clear();
        hmap_destroy(&route_map);
        name_table_uninit();
    }
}

/* Run periodically to update the locally maintained routing table. */
void
route_table_run(void)
{
    if (nln) {
        rtnetlink_link_run();
        nln_run(nln);
    }
}

/* Causes poll_block() to wake up when route_table updates are required. */
void
route_table_wait(void)
{
    if (nln) {
        rtnetlink_link_wait();
        nln_wait(nln);
    }
}

static int
route_table_reset(void)
{
    int error;
    struct nl_dump dump;
    struct rtgenmsg *rtmsg;
    struct ofpbuf request, reply;
    static struct nl_sock *rtnl_sock;

    route_map_clear();
    route_table_valid = true;

    error = nl_sock_create(NETLINK_ROUTE, &rtnl_sock);
    if (error) {
        VLOG_WARN_RL(&rl, "failed to reset routing table, "
                     "cannot create RTNETLINK_ROUTE socket");
        return error;
    }

    ofpbuf_init(&request, 0);

    nl_msg_put_nlmsghdr(&request, sizeof *rtmsg, RTM_GETROUTE, NLM_F_REQUEST);

    rtmsg = ofpbuf_put_zeros(&request, sizeof *rtmsg);
    rtmsg->rtgen_family = AF_INET;

    nl_dump_start(&dump, rtnl_sock, &request);
    ofpbuf_uninit(&request);

    while (nl_dump_next(&dump, &reply)) {
        struct route_table_msg msg;

        if (route_table_parse(&reply, &msg)) {
            route_table_handle_msg(&msg);
        }
    }

    error = nl_dump_done(&dump);
    nl_sock_destroy(rtnl_sock);

    return error;
}


static bool
route_table_parse(struct ofpbuf *buf, struct route_table_msg *change)
{
    bool parsed;

    static const struct nl_policy policy[] = {
        [RTA_DST] = { .type = NL_A_U32, .optional = true  },
        [RTA_OIF] = { .type = NL_A_U32, .optional = false },
    };

    static struct nlattr *attrs[ARRAY_SIZE(policy)];

    parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct rtmsg),
                             policy, attrs, ARRAY_SIZE(policy));

    if (parsed) {
        const struct rtmsg *rtm;
        const struct nlmsghdr *nlmsg;

        nlmsg = buf->data;
        rtm = (const struct rtmsg *) ((const char *) buf->data + NLMSG_HDRLEN);

        if (rtm->rtm_family != AF_INET) {
            VLOG_DBG_RL(&rl, "received non AF_INET rtnetlink route message");
            return false;
        }

        memset(change, 0, sizeof *change);
        change->relevant = true;

        if (rtm->rtm_scope == RT_SCOPE_NOWHERE) {
            change->relevant = false;
        }

        if (rtm->rtm_type != RTN_UNICAST &&
            rtm->rtm_type != RTN_LOCAL) {
            change->relevant = false;
        }

        change->nlmsg_type     = nlmsg->nlmsg_type;
        change->rd.rtm_dst_len = rtm->rtm_dst_len;
        change->rd.rta_oif     = nl_attr_get_u32(attrs[RTA_OIF]);

        if (attrs[RTA_DST]) {
            change->rd.rta_dst = ntohl(nl_attr_get_be32(attrs[RTA_DST]));
        }

    } else {
        VLOG_DBG_RL(&rl, "received unparseable rtnetlink route message");
    }

    return parsed;
}

static void
route_table_change(const struct route_table_msg *change OVS_UNUSED,
                   void *aux OVS_UNUSED)
{
    route_table_valid = false;
}

static void
route_table_handle_msg(const struct route_table_msg *change)
{
    if (change->relevant && change->nlmsg_type == RTM_NEWROUTE &&
        !route_node_lookup(&change->rd)) {
        struct route_node *rn;

        rn = xzalloc(sizeof *rn);
        memcpy(&rn->rd, &change->rd, sizeof change->rd);

        hmap_insert(&route_map, &rn->node, hash_route_data(&rn->rd));
    }
}

static struct route_node *
route_node_lookup(const struct route_data *rd)
{
    struct route_node *rn;

    HMAP_FOR_EACH_WITH_HASH(rn, node, hash_route_data(rd), &route_map) {
        if (!memcmp(&rn->rd, rd, sizeof *rd)) {
            return rn;
        }
    }

    return NULL;
}

static struct route_node *
route_node_lookup_by_ip(uint32_t ip)
{
    int dst_len;
    struct route_node *rn, *rn_ret;

    dst_len = -1;
    rn_ret  = NULL;

    HMAP_FOR_EACH(rn, node, &route_map) {
        uint32_t mask = 0xffffffff << (32 - rn->rd.rtm_dst_len);

        if (rn->rd.rta_dst == 0 && rn->rd.rtm_dst_len == 0) {
            /* Default route. */
            continue;
        }

        if (rn->rd.rtm_dst_len > dst_len &&
            (ip & mask) == (rn->rd.rta_dst & mask)) {
            rn_ret  = rn;
            dst_len = rn->rd.rtm_dst_len;
        }
    }

    return rn_ret;
}

static void
route_map_clear(void)
{
    struct route_node *rn, *rn_next;

    HMAP_FOR_EACH_SAFE(rn, rn_next, node, &route_map) {
        hmap_remove(&route_map, &rn->node);
        free(rn);
    }
}

static uint32_t
hash_route_data(const struct route_data *rd)
{
    return hash_bytes(rd, sizeof *rd, 0);
}

/* name_table . */

static void
name_table_init(void)
{
    hmap_init(&name_map);
    name_notifier = rtnetlink_link_notifier_create(name_table_change, NULL);
    name_table_valid = false;
}

static void
name_table_uninit(void)
{
    rtnetlink_link_notifier_destroy(name_notifier);
    name_notifier = NULL;
    name_map_clear();
    hmap_destroy(&name_map);
}

static int
name_table_reset(void)
{
    int error;
    struct nl_dump dump;
    struct rtgenmsg *rtmsg;
    struct ofpbuf request, reply;
    static struct nl_sock *rtnl_sock;

    name_table_valid = true;
    name_map_clear();
    error = nl_sock_create(NETLINK_ROUTE, &rtnl_sock);
    if (error) {
        VLOG_WARN_RL(&rl, "failed to create NETLINK_ROUTE socket");
        return error;
    }

    ofpbuf_init(&request, 0);
    nl_msg_put_nlmsghdr(&request, sizeof *rtmsg, RTM_GETLINK, NLM_F_REQUEST);
    rtmsg = ofpbuf_put_zeros(&request, sizeof *rtmsg);
    rtmsg->rtgen_family = AF_INET;

    nl_dump_start(&dump, rtnl_sock, &request);
    ofpbuf_uninit(&request);

    while (nl_dump_next(&dump, &reply)) {
        struct rtnetlink_link_change change;

        if (rtnetlink_link_parse(&reply, &change)
            && change.nlmsg_type == RTM_NEWLINK
            && !name_node_lookup(change.ifi_index)) {
            struct name_node *nn;

            nn = xzalloc(sizeof *nn);
            nn->ifi_index = change.ifi_index;
            ovs_strlcpy(nn->ifname, change.ifname, IFNAMSIZ);
            hmap_insert(&name_map, &nn->node, hash_int(nn->ifi_index, 0));
        }
    }
    nl_sock_destroy(rtnl_sock);
    return nl_dump_done(&dump);
}

static void
name_table_change(const struct rtnetlink_link_change *change OVS_UNUSED,
                  void *aux OVS_UNUSED)
{
    /* Changes to interface status can cause routing table changes that some
     * versions of the linux kernel do not advertise for some reason. */
    route_table_valid = false;
    name_table_valid = false;
}

static struct name_node *
name_node_lookup(int ifi_index)
{
    struct name_node *nn;

    HMAP_FOR_EACH_WITH_HASH(nn, node, hash_int(ifi_index, 0), &name_map) {
        if (nn->ifi_index == ifi_index) {
            return nn;
        }
    }

    return NULL;
}

static void
name_map_clear(void)
{
    struct name_node *nn, *nn_next;

    HMAP_FOR_EACH_SAFE(nn, nn_next, node, &name_map) {
        hmap_remove(&name_map, &nn->node);
        free(nn);
    }
}