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1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2016 Lennart Poettering | |
5 | ||
6 | systemd is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | systemd is distributed in the hope that it will be useful, but | |
12 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
18 | ***/ | |
19 | ||
20 | #include <endian.h> | |
21 | #include <inttypes.h> | |
22 | #include <string.h> | |
23 | ||
24 | #include "fd-util.h" | |
25 | #include "fileio.h" | |
26 | #include "hostname-util.h" | |
27 | #include "lldp.h" | |
28 | #include "networkd-lldp-tx.h" | |
29 | #include "random-util.h" | |
30 | #include "socket-util.h" | |
31 | #include "string-util.h" | |
32 | #include "unaligned.h" | |
33 | ||
34 | /* The LLDP spec calls this "txFastInit", see 9.2.5.19 */ | |
35 | #define LLDP_TX_FAST_INIT 4U | |
36 | ||
37 | /* The LLDP spec calls this "msgTxHold", see 9.2.5.6 */ | |
38 | #define LLDP_TX_HOLD 4U | |
39 | ||
40 | /* The jitter range to add, see 9.2.2. */ | |
41 | #define LLDP_JITTER_USEC (400U * USEC_PER_MSEC) | |
42 | ||
43 | /* The LLDP spec calls this msgTxInterval, but we subtract half the jitter off it. */ | |
44 | #define LLDP_TX_INTERVAL_USEC (30U * USEC_PER_SEC - LLDP_JITTER_USEC / 2) | |
45 | ||
46 | /* The LLDP spec calls this msgFastTx, but we subtract half the jitter off it. */ | |
47 | #define LLDP_FAST_TX_USEC (1U * USEC_PER_SEC - LLDP_JITTER_USEC / 2) | |
48 | ||
49 | static int lldp_write_tlv_header(uint8_t **p, uint8_t id, size_t sz) { | |
50 | assert(p); | |
51 | ||
52 | if (id > 127) | |
53 | return -EBADMSG; | |
54 | if (sz > 511) | |
55 | return -ENOBUFS; | |
56 | ||
57 | (*p)[0] = (id << 1) | !!(sz & 256); | |
58 | (*p)[1] = sz & 255; | |
59 | ||
60 | *p = *p + 2; | |
61 | return 0; | |
62 | } | |
63 | ||
64 | static int lldp_make_packet( | |
65 | const struct ether_addr *hwaddr, | |
66 | const char *machine_id, | |
67 | const char *ifname, | |
68 | uint16_t ttl, | |
69 | const char *port_description, | |
70 | const char *hostname, | |
71 | const char *pretty_hostname, | |
72 | uint16_t system_capabilities, | |
73 | uint16_t enabled_capabilities, | |
74 | void **ret, size_t *sz) { | |
75 | ||
76 | size_t machine_id_length, ifname_length, port_description_length = 0, hostname_length = 0, pretty_hostname_length = 0; | |
77 | _cleanup_free_ void *packet = NULL; | |
78 | struct ether_header *h; | |
79 | uint8_t *p; | |
80 | size_t l; | |
81 | int r; | |
82 | ||
83 | assert(hwaddr); | |
84 | assert(machine_id); | |
85 | assert(ifname); | |
86 | assert(ret); | |
87 | assert(sz); | |
88 | ||
89 | machine_id_length = strlen(machine_id); | |
90 | ifname_length = strlen(ifname); | |
91 | ||
92 | if (port_description) | |
93 | port_description_length = strlen(port_description); | |
94 | ||
95 | if (hostname) | |
96 | hostname_length = strlen(hostname); | |
97 | ||
98 | if (pretty_hostname) | |
99 | pretty_hostname_length = strlen(pretty_hostname); | |
100 | ||
101 | l = sizeof(struct ether_header) + | |
102 | /* Chassis ID */ | |
103 | 2 + 1 + machine_id_length + | |
104 | /* Port ID */ | |
105 | 2 + 1 + ifname_length + | |
106 | /* TTL */ | |
107 | 2 + 2 + | |
108 | /* System Capabilities */ | |
109 | 2 + 4 + | |
110 | /* End */ | |
111 | 2; | |
112 | ||
113 | /* Port Description */ | |
114 | if (port_description) | |
115 | l += 2 + port_description_length; | |
116 | ||
117 | /* System Name */ | |
118 | if (hostname) | |
119 | l += 2 + hostname_length; | |
120 | ||
121 | /* System Description */ | |
122 | if (pretty_hostname) | |
123 | l += 2 + pretty_hostname_length; | |
124 | ||
125 | packet = malloc(l); | |
126 | if (!packet) | |
127 | return -ENOMEM; | |
128 | ||
129 | h = (struct ether_header*) packet; | |
130 | h->ether_type = htobe16(ETHERTYPE_LLDP); | |
131 | memcpy(h->ether_dhost, &(struct ether_addr) { LLDP_MULTICAST_ADDR }, ETH_ALEN); | |
132 | memcpy(h->ether_shost, hwaddr, ETH_ALEN); | |
133 | ||
134 | p = (uint8_t*) packet + sizeof(struct ether_header); | |
135 | ||
136 | r = lldp_write_tlv_header(&p, LLDP_TYPE_CHASSIS_ID, 1 + machine_id_length); | |
137 | if (r < 0) | |
138 | return r; | |
139 | *(p++) = LLDP_CHASSIS_SUBTYPE_LOCALLY_ASSIGNED; | |
140 | p = mempcpy(p, machine_id, machine_id_length); | |
141 | ||
142 | r = lldp_write_tlv_header(&p, LLDP_TYPE_PORT_ID, 1 + ifname_length); | |
143 | if (r < 0) | |
144 | return r; | |
145 | *(p++) = LLDP_PORT_SUBTYPE_INTERFACE_NAME; | |
146 | p = mempcpy(p, ifname, ifname_length); | |
147 | ||
148 | r = lldp_write_tlv_header(&p, LLDP_TYPE_TTL, 2); | |
149 | if (r < 0) | |
150 | return r; | |
151 | unaligned_write_be16(p, ttl); | |
152 | p += 2; | |
153 | ||
154 | if (port_description) { | |
155 | r = lldp_write_tlv_header(&p, LLDP_TYPE_PORT_DESCRIPTION, port_description_length); | |
156 | if (r < 0) | |
157 | return r; | |
158 | p = mempcpy(p, port_description, port_description_length); | |
159 | } | |
160 | ||
161 | if (hostname) { | |
162 | r = lldp_write_tlv_header(&p, LLDP_TYPE_SYSTEM_NAME, hostname_length); | |
163 | if (r < 0) | |
164 | return r; | |
165 | p = mempcpy(p, hostname, hostname_length); | |
166 | } | |
167 | ||
168 | if (pretty_hostname) { | |
169 | r = lldp_write_tlv_header(&p, LLDP_TYPE_SYSTEM_DESCRIPTION, pretty_hostname_length); | |
170 | if (r < 0) | |
171 | return r; | |
172 | p = mempcpy(p, pretty_hostname, pretty_hostname_length); | |
173 | } | |
174 | ||
175 | r = lldp_write_tlv_header(&p, LLDP_TYPE_SYSTEM_CAPABILITIES, 4); | |
176 | if (r < 0) | |
177 | return r; | |
178 | unaligned_write_be16(p, system_capabilities); | |
179 | p += 2; | |
180 | unaligned_write_be16(p, enabled_capabilities); | |
181 | p += 2; | |
182 | ||
183 | r = lldp_write_tlv_header(&p, LLDP_TYPE_END, 0); | |
184 | if (r < 0) | |
185 | return r; | |
186 | ||
187 | assert(p == (uint8_t*) packet + l); | |
188 | ||
189 | *ret = packet; | |
190 | *sz = l; | |
191 | ||
192 | packet = NULL; | |
193 | return 0; | |
194 | } | |
195 | ||
196 | static int lldp_send_packet(int ifindex, const void *packet, size_t packet_size) { | |
197 | ||
198 | union sockaddr_union sa = { | |
199 | .ll.sll_family = AF_PACKET, | |
200 | .ll.sll_protocol = htobe16(ETHERTYPE_LLDP), | |
201 | .ll.sll_ifindex = ifindex, | |
202 | .ll.sll_halen = ETH_ALEN, | |
203 | .ll.sll_addr = LLDP_MULTICAST_ADDR, | |
204 | }; | |
205 | ||
206 | _cleanup_close_ int fd = -1; | |
207 | ssize_t l; | |
208 | ||
209 | assert(ifindex > 0); | |
210 | assert(packet || packet_size <= 0); | |
211 | ||
212 | fd = socket(PF_PACKET, SOCK_RAW|SOCK_CLOEXEC, IPPROTO_RAW); | |
213 | if (fd < 0) | |
214 | return -errno; | |
215 | ||
216 | l = sendto(fd, packet, packet_size, MSG_NOSIGNAL, &sa.sa, sizeof(sa.ll)); | |
217 | if (l < 0) | |
218 | return -errno; | |
219 | ||
220 | if ((size_t) l != packet_size) | |
221 | return -EIO; | |
222 | ||
223 | return 0; | |
224 | } | |
225 | ||
226 | static int link_send_lldp(Link *link) { | |
227 | char machine_id_string[SD_ID128_STRING_MAX]; | |
228 | _cleanup_free_ char *hostname = NULL, *pretty_hostname = NULL; | |
229 | _cleanup_free_ void *packet = NULL; | |
230 | size_t packet_size = 0; | |
231 | sd_id128_t machine_id; | |
232 | uint16_t caps; | |
233 | usec_t ttl; | |
234 | int r; | |
235 | ||
236 | r = sd_id128_get_machine(&machine_id); | |
237 | if (r < 0) | |
238 | return r; | |
239 | ||
240 | (void) gethostname_strict(&hostname); | |
241 | (void) parse_env_file("/etc/machine-info", NEWLINE, "PRETTY_HOSTNAME", &pretty_hostname, NULL); | |
242 | ||
243 | ttl = DIV_ROUND_UP(LLDP_TX_INTERVAL_USEC * LLDP_TX_HOLD + 1, USEC_PER_SEC); | |
244 | if (ttl > (usec_t) UINT16_MAX) | |
245 | ttl = (usec_t) UINT16_MAX; | |
246 | ||
247 | caps = (link->network && link->network->ip_forward != ADDRESS_FAMILY_NO) ? | |
248 | LLDP_SYSTEM_CAPABILITIES_ROUTER : | |
249 | LLDP_SYSTEM_CAPABILITIES_STATION; | |
250 | ||
251 | r = lldp_make_packet(&link->mac, | |
252 | sd_id128_to_string(machine_id, machine_id_string), | |
253 | link->ifname, | |
254 | (uint16_t) ttl, | |
255 | link->network ? link->network->description : NULL, | |
256 | hostname, | |
257 | pretty_hostname, | |
258 | LLDP_SYSTEM_CAPABILITIES_STATION|LLDP_SYSTEM_CAPABILITIES_BRIDGE|LLDP_SYSTEM_CAPABILITIES_ROUTER, | |
259 | caps, | |
260 | &packet, &packet_size); | |
261 | if (r < 0) | |
262 | return r; | |
263 | ||
264 | return lldp_send_packet(link->ifindex, packet, packet_size); | |
265 | } | |
266 | ||
267 | static int on_lldp_timer(sd_event_source *s, usec_t t, void *userdata) { | |
268 | Link *link = userdata; | |
269 | usec_t current, delay, next; | |
270 | int r; | |
271 | ||
272 | assert(s); | |
273 | assert(userdata); | |
274 | ||
275 | log_link_debug(link, "Sending LLDP packet..."); | |
276 | ||
277 | r = link_send_lldp(link); | |
278 | if (r < 0) | |
279 | log_link_debug_errno(link, r, "Failed to send LLDP packet, ignoring: %m"); | |
280 | ||
281 | if (link->lldp_tx_fast > 0) | |
282 | link->lldp_tx_fast--; | |
283 | ||
284 | assert_se(sd_event_now(sd_event_source_get_event(s), clock_boottime_or_monotonic(), ¤t) >= 0); | |
285 | ||
286 | delay = link->lldp_tx_fast > 0 ? LLDP_FAST_TX_USEC : LLDP_TX_INTERVAL_USEC; | |
287 | next = usec_add(usec_add(current, delay), (usec_t) random_u64() % LLDP_JITTER_USEC); | |
288 | ||
289 | r = sd_event_source_set_time(s, next); | |
290 | if (r < 0) | |
291 | return log_link_error_errno(link, r, "Failed to restart LLDP timer: %m"); | |
292 | ||
293 | r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT); | |
294 | if (r < 0) | |
295 | return log_link_error_errno(link, r, "Failed to enable LLDP timer: %m"); | |
296 | ||
297 | return 0; | |
298 | } | |
299 | ||
300 | int link_lldp_tx_start(Link *link) { | |
301 | usec_t next; | |
302 | int r; | |
303 | ||
304 | assert(link); | |
305 | ||
306 | /* Starts the LLDP transmission in "fast" mode. If it is already started, turns "fast" mode back on again. */ | |
307 | ||
308 | link->lldp_tx_fast = LLDP_TX_FAST_INIT; | |
309 | ||
310 | next = usec_add(usec_add(now(clock_boottime_or_monotonic()), LLDP_FAST_TX_USEC), | |
311 | (usec_t) random_u64() % LLDP_JITTER_USEC); | |
312 | ||
313 | if (link->lldp_tx_event_source) { | |
314 | usec_t old; | |
315 | ||
316 | /* Lower the timeout, maybe */ | |
317 | r = sd_event_source_get_time(link->lldp_tx_event_source, &old); | |
318 | if (r < 0) | |
319 | return r; | |
320 | ||
321 | if (old <= next) | |
322 | return 0; | |
323 | ||
324 | return sd_event_source_set_time(link->lldp_tx_event_source, next); | |
325 | } else { | |
326 | r = sd_event_add_time( | |
327 | link->manager->event, | |
328 | &link->lldp_tx_event_source, | |
329 | clock_boottime_or_monotonic(), | |
330 | next, | |
331 | 0, | |
332 | on_lldp_timer, | |
333 | link); | |
334 | if (r < 0) | |
335 | return r; | |
336 | ||
337 | (void) sd_event_source_set_description(link->lldp_tx_event_source, "lldp-tx"); | |
338 | } | |
339 | ||
340 | return 0; | |
341 | } | |
342 | ||
343 | void link_lldp_tx_stop(Link *link) { | |
344 | assert(link); | |
345 | ||
346 | link->lldp_tx_event_source = sd_event_source_unref(link->lldp_tx_event_source); | |
347 | } |