odhpc6c: status code support in reply
[odhcp6c.git] / src / dhcpv6.c
1 /**
2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License v2 as published by
6  * the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  *
13  */
14
15 #include <time.h>
16 #include <fcntl.h>
17 #include <errno.h>
18 #include <stdlib.h>
19 #include <signal.h>
20 #include <limits.h>
21 #include <resolv.h>
22 #include <string.h>
23 #include <unistd.h>
24 #include <syslog.h>
25 #include <stdbool.h>
26 #include <sys/time.h>
27 #include <sys/ioctl.h>
28 #include <sys/socket.h>
29 #include <netinet/in.h>
30
31 #include <net/if.h>
32 #include <net/ethernet.h>
33
34 #include "odhcp6c.h"
35 #include "md5.h"
36
37
38 #define ALL_DHCPV6_RELAYS {{{0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
39                 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02}}}
40 #define DHCPV6_CLIENT_PORT 546
41 #define DHCPV6_SERVER_PORT 547
42 #define DHCPV6_DUID_LLADDR 3
43 #define DHCPV6_REQ_DELAY 1
44
45
46 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
47                 const uint8_t transaction[3], enum dhcpv6_msg type);
48
49 static int dhcpv6_parse_ia(void *opt, void *end);
50
51 static int dhcpv6_calc_refresh_timers(void);
52 static void dhcpv6_handle_status_code(_unused const enum dhcpv6_msg orig,
53                 const uint16_t code, const void *status_msg, const int len,
54                 int *ret);
55 static void dhcpv6_handle_ia_status_code(const enum dhcpv6_msg orig,
56                 const struct dhcpv6_ia_hdr *ia_hdr, const uint16_t code,
57                 const void *status_msg, const int len,
58                 bool handled_status_codes[_DHCPV6_Status_Max],
59                 int *ret);
60
61 static reply_handler dhcpv6_handle_reply;
62 static reply_handler dhcpv6_handle_advert;
63 static reply_handler dhcpv6_handle_rebind_reply;
64 static reply_handler dhcpv6_handle_reconfigure;
65 static int dhcpv6_commit_advert(void);
66
67
68
69 // RFC 3315 - 5.5 Timeout and Delay values
70 static struct dhcpv6_retx dhcpv6_retx[_DHCPV6_MSG_MAX] = {
71         [DHCPV6_MSG_UNKNOWN] = {false, 1, 120, 0, "<POLL>",
72                         dhcpv6_handle_reconfigure, NULL},
73         [DHCPV6_MSG_SOLICIT] = {true, 1, 3600, 0, "SOLICIT",
74                         dhcpv6_handle_advert, dhcpv6_commit_advert},
75         [DHCPV6_MSG_REQUEST] = {true, 1, 30, 10, "REQUEST",
76                         dhcpv6_handle_reply, NULL},
77         [DHCPV6_MSG_RENEW] = {false, 10, 600, 0, "RENEW",
78                         dhcpv6_handle_reply, NULL},
79         [DHCPV6_MSG_REBIND] = {false, 10, 600, 0, "REBIND",
80                         dhcpv6_handle_rebind_reply, NULL},
81         [DHCPV6_MSG_RELEASE] = {false, 1, 0, 5, "RELEASE", NULL, NULL},
82         [DHCPV6_MSG_DECLINE] = {false, 1, 0, 5, "DECLINE", NULL, NULL},
83         [DHCPV6_MSG_INFO_REQ] = {true, 1, 120, 0, "INFOREQ",
84                         dhcpv6_handle_reply, NULL},
85 };
86
87
88 // Sockets
89 static int sock = -1;
90 static int ifindex = -1;
91 static int64_t t1 = 0, t2 = 0, t3 = 0;
92
93 // IA states
94 static int request_prefix = -1;
95 static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE, pd_mode = IA_MODE_NONE;
96 static bool accept_reconfig = false;
97
98 // Reconfigure key
99 static uint8_t reconf_key[16];
100
101
102
103 int init_dhcpv6(const char *ifname, int request_pd, int sol_timeout)
104 {
105         request_prefix = request_pd;
106         dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = sol_timeout;
107
108         sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
109
110         // Detect interface
111         struct ifreq ifr;
112         strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
113         if (ioctl(sock, SIOCGIFINDEX, &ifr))
114                 return -1;
115         ifindex = ifr.ifr_ifindex;
116
117         // Create client DUID
118         size_t client_id_len;
119         odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
120         if (client_id_len == 0) {
121                 ioctl(sock, SIOCGIFHWADDR, &ifr);
122                 uint8_t duid[14] = {0, DHCPV6_OPT_CLIENTID, 0, 10, 0,
123                                 DHCPV6_DUID_LLADDR, 0, 1};
124                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
125
126                 uint8_t zero[ETHER_ADDR_LEN] = {0, 0, 0, 0, 0, 0};
127                 struct ifreq ifs[100], *ifp, *ifend;
128                 struct ifconf ifc;
129                 ifc.ifc_req = ifs;
130                 ifc.ifc_len = sizeof(ifs);
131
132                 if (!memcmp(&duid[8], zero, ETHER_ADDR_LEN) &&
133                                 ioctl(sock, SIOCGIFCONF, &ifc) >= 0) {
134                         // If our interface doesn't have an address...
135                         ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
136                         for (ifp = ifc.ifc_req; ifp < ifend &&
137                                         !memcmp(&duid[8], zero, 6); ifp++) {
138                                 memcpy(ifr.ifr_name, ifp->ifr_name,
139                                                 sizeof(ifr.ifr_name));
140                                 ioctl(sock, SIOCGIFHWADDR, &ifr);
141                                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data,
142                                                 ETHER_ADDR_LEN);
143                         }
144                 }
145
146                 odhcp6c_add_state(STATE_CLIENT_ID, duid, sizeof(duid));
147         }
148
149         // Create ORO
150         uint16_t oro[] = {
151                         htons(DHCPV6_OPT_SIP_SERVER_D),
152                         htons(DHCPV6_OPT_SIP_SERVER_A),
153                         htons(DHCPV6_OPT_DNS_SERVERS),
154                         htons(DHCPV6_OPT_DNS_DOMAIN),
155                         htons(DHCPV6_OPT_NTP_SERVER),
156                         htons(DHCPV6_OPT_SIP_SERVER_A),
157                         htons(DHCPV6_OPT_AFTR_NAME),
158                         htons(DHCPV6_OPT_PD_EXCLUDE),
159 #ifdef EXT_PREFIX_CLASS
160                         htons(DHCPV6_OPT_PREFIX_CLASS),
161 #endif
162         };
163         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
164
165
166         // Configure IPv6-options
167         int val = 1;
168         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
169         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
170         val = 0;
171         setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
172         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
173
174         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
175                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
176         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
177                 return -1;
178
179         return 0;
180 }
181
182
183 void dhcpv6_set_ia_mode(enum odhcp6c_ia_mode na, enum odhcp6c_ia_mode pd)
184 {
185         na_mode = na;
186         pd_mode = pd;
187 }
188
189
190 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
191 {
192         // Build FQDN
193         char fqdn_buf[256];
194         gethostname(fqdn_buf, sizeof(fqdn_buf));
195         struct {
196                 uint16_t type;
197                 uint16_t len;
198                 uint8_t flags;
199                 uint8_t data[256];
200         } fqdn;
201         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
202                         sizeof(fqdn.data), NULL, NULL);
203         fqdn.type = htons(DHCPV6_OPT_FQDN);
204         fqdn.len = htons(fqdn_len - 4);
205         fqdn.flags = 0;
206
207
208         // Build Client ID
209         size_t cl_id_len;
210         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
211
212         // Get Server ID
213         size_t srv_id_len;
214         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
215
216         // Build IA_PDs
217         size_t ia_pd_entries, ia_pd_len = 0;
218         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
219         ia_pd_entries /= sizeof(*e);
220         struct dhcpv6_ia_hdr hdr_ia_pd = {
221                 htons(DHCPV6_OPT_IA_PD),
222                 htons(sizeof(hdr_ia_pd) - 4),
223                 1, 0, 0
224         };
225
226
227         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
228         for (size_t i = 0; i < ia_pd_entries; ++i) {
229                 uint8_t ex_len = 0;
230                 if (e[i].priority > 0)
231                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
232
233                 struct dhcpv6_ia_prefix p = {
234                         .type = htons(DHCPV6_OPT_IA_PREFIX),
235                         .len = htons(sizeof(p) - 4U + ex_len),
236                         .prefix = e[i].length,
237                         .addr = e[i].target
238                 };
239
240                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
241                 ia_pd_len += sizeof(p);
242
243                 if (ex_len) {
244                         ia_pd[ia_pd_len++] = 0;
245                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
246                         ia_pd[ia_pd_len++] = 0;
247                         ia_pd[ia_pd_len++] = ex_len - 4;
248                         ia_pd[ia_pd_len++] = e[i].priority;
249
250                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
251                         excl >>= (64 - e[i].priority);
252                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
253
254                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
255                                 ia_pd[ia_pd_len + i] = excl & 0xff;
256                         ia_pd_len += ex_len - 5;
257                 }
258         }
259
260         struct dhcpv6_ia_prefix pref = {
261                 .type = htons(DHCPV6_OPT_IA_PREFIX),
262                 .len = htons(25), .prefix = request_prefix
263         };
264         if (request_prefix > 0 && ia_pd_len == 0 && type == DHCPV6_MSG_SOLICIT) {
265                 ia_pd = (uint8_t*)&pref;
266                 ia_pd_len = sizeof(pref);
267         }
268         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
269
270         // Build IA_NAs
271         size_t ia_na_entries, ia_na_len = 0;
272         void *ia_na = NULL;
273         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
274         ia_na_entries /= sizeof(*e);
275
276         struct dhcpv6_ia_hdr hdr_ia_na = {
277                 htons(DHCPV6_OPT_IA_NA),
278                 htons(sizeof(hdr_ia_na) - 4),
279                 1, 0, 0
280         };
281
282         struct dhcpv6_ia_addr pa[ia_na_entries];
283         for (size_t i = 0; i < ia_na_entries; ++i) {
284                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
285                 pa[i].len = htons(sizeof(pa[i]) - 4U);
286                 pa[i].addr = e[i].target;
287                 pa[i].preferred = 0;
288                 pa[i].valid = 0;
289         }
290
291         ia_na = pa;
292         ia_na_len = sizeof(pa);
293         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
294
295         // Reconfigure Accept
296         struct {
297                 uint16_t type;
298                 uint16_t length;
299         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
300
301         // Request Information Refresh
302         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
303
304         // Prepare Header
305         size_t oro_len;
306         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
307         struct {
308                 uint8_t type;
309                 uint8_t trid[3];
310                 uint16_t elapsed_type;
311                 uint16_t elapsed_len;
312                 uint16_t elapsed_value;
313                 uint16_t oro_type;
314                 uint16_t oro_len;
315         } hdr = {
316                 type, {trid[0], trid[1], trid[2]},
317                 htons(DHCPV6_OPT_ELAPSED), htons(2),
318                         htons((ecs > 0xffff) ? 0xffff : ecs),
319                 htons(DHCPV6_OPT_ORO), htons(oro_len),
320         };
321
322         struct iovec iov[] = {
323                 {&hdr, sizeof(hdr)},
324                 {oro, oro_len},
325                 {&oro_refresh, 0},
326                 {cl_id, cl_id_len},
327                 {srv_id, srv_id_len},
328                 {&reconf_accept, sizeof(reconf_accept)},
329                 {&fqdn, fqdn_len},
330                 {&hdr_ia_na, sizeof(hdr_ia_na)},
331                 {ia_na, ia_na_len},
332                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
333                 {ia_pd, ia_pd_len},
334         };
335
336         size_t cnt = ARRAY_SIZE(iov);
337         if (type == DHCPV6_MSG_INFO_REQ) {
338                 cnt = 5;
339                 iov[2].iov_len = sizeof(oro_refresh);
340                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
341         } else if (!request_prefix) {
342                 cnt = 9;
343         }
344
345         // Disable IAs if not used
346         if (type != DHCPV6_MSG_SOLICIT) {
347                 iov[5].iov_len = 0;
348                 if (ia_na_len == 0)
349                         iov[7].iov_len = 0;
350                 if (ia_pd_len == 0)
351                         iov[9].iov_len = 0;
352         }
353
354         if (na_mode == IA_MODE_NONE)
355                 iov[7].iov_len = 0;
356
357         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
358                 0, ALL_DHCPV6_RELAYS, ifindex};
359         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
360
361         sendmsg(sock, &msg, 0);
362 }
363
364
365 static int64_t dhcpv6_rand_delay(int64_t time)
366 {
367         int random;
368         odhcp6c_random(&random, sizeof(random));
369         return (time * ((int64_t)random % 1000LL)) / 10000LL;
370 }
371
372
373 int dhcpv6_request(enum dhcpv6_msg type)
374 {
375         uint8_t buf[1536], rc = 0;
376         uint64_t timeout = UINT32_MAX;
377         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
378
379         if (retx->delay) {
380                 struct timespec ts = {0, 0};
381                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
382                 nanosleep(&ts, NULL);
383         }
384
385         if (type == DHCPV6_MSG_UNKNOWN)
386                 timeout = t1;
387         else if (type == DHCPV6_MSG_RENEW)
388                 timeout = (t2 > t1) ? t2 - t1 : 0;
389         else if (type == DHCPV6_MSG_REBIND)
390                 timeout = (t3 > t2) ? t3 - t2 : 0;
391
392         if (timeout == 0)
393                 return -1;
394
395         syslog(LOG_NOTICE, "Starting %s transaction (timeout %llus, max rc %d)", retx->name, timeout, retx->max_rc);
396
397         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
398
399         // Generate transaction ID
400         uint8_t trid[3] = {0, 0, 0};
401         if (type != DHCPV6_MSG_UNKNOWN)
402                 odhcp6c_random(trid, sizeof(trid));
403         ssize_t len = -1;
404         int64_t rto = 0;
405
406         do {
407                 if (rto == 0) {
408                         int64_t delay = dhcpv6_rand_delay(retx->init_timeo * 1000);
409
410                         // First RT MUST be strictly greater than IRT for solicit messages (RFC3313 17.1.2)
411                         while (type == DHCPV6_MSG_SOLICIT && delay <= 0)
412                                 delay = dhcpv6_rand_delay(retx->init_timeo * 1000);
413
414                         rto = (retx->init_timeo * 1000 + delay);
415                 }
416                 else
417                         rto = (2 * rto + dhcpv6_rand_delay(rto));
418
419                 if (retx->max_timeo && (rto >= retx->max_timeo * 1000))
420                         rto = retx->max_timeo * 1000 +
421                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
422
423                 // Calculate end for this round and elapsed time
424                 uint64_t round_end = round_start + rto;
425                 elapsed = round_start - start;
426
427                 // Don't wait too long
428                 if (round_end - start > timeout * 1000)
429                         round_end = timeout * 1000 + start;
430
431                 // Built and send package
432                 if (type != DHCPV6_MSG_UNKNOWN) {
433                         syslog(LOG_NOTICE, "Send %s message (elapsed %llums, rc %d)", retx->name, elapsed, rc);
434                         dhcpv6_send(type, trid, elapsed / 10);
435                         rc++;
436                 }
437
438                 // Receive rounds
439                 for (; len < 0 && round_start < round_end;
440                                 round_start = odhcp6c_get_milli_time()) {
441                         // Check for pending signal
442                         if (odhcp6c_signal_process())
443                                 return -1;
444
445                         // Set timeout for receiving
446                         uint64_t t = round_end - round_start;
447                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
448                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
449                                         &timeout, sizeof(timeout));
450
451                         // Receive cycle
452                         len = recv(sock, buf, sizeof(buf), 0);
453
454                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
455                                 len = -1;
456
457                         if (len > 0) {
458                                 uint8_t *opt = &buf[4];
459                                 uint8_t *opt_end = opt + len - 4;
460
461                                 round_start = odhcp6c_get_milli_time();
462                                 elapsed = round_start - start;
463                                 syslog(LOG_NOTICE, "Got a valid reply after "
464                                                 "%llums", elapsed);
465
466                                 if (retx->handler_reply)
467                                         len = retx->handler_reply(
468                                                         type, rc, opt, opt_end);
469
470                                 if (len > 0 && round_end - round_start > 1000)
471                                         round_end = 1000 + round_start;
472                         }
473                 }
474
475                 // Allow
476                 if (retx->handler_finish)
477                         len = retx->handler_finish();
478         } while (len < 0 && ((elapsed / 1000 < timeout) && (!retx->max_rc || rc < retx->max_rc)));
479
480         return len;
481 }
482
483
484 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
485                 const uint8_t transaction[3], enum dhcpv6_msg type)
486 {
487         const struct dhcpv6_header *rep = buf;
488         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
489                         transaction, sizeof(rep->tr_id)))
490                 return false; // Invalid reply
491
492         if (type == DHCPV6_MSG_SOLICIT) {
493                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
494                                 rep->msg_type != DHCPV6_MSG_REPLY)
495                         return false;
496         } else if (type == DHCPV6_MSG_UNKNOWN) {
497                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
498                         return false;
499         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
500                 return false;
501         }
502
503         uint8_t *end = ((uint8_t*)buf) + len, *odata;
504         uint16_t otype, olen;
505         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
506
507         size_t client_id_len, server_id_len;
508         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
509         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
510
511         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
512                 if (otype == DHCPV6_OPT_CLIENTID) {
513                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
514                                         &odata[-4], client_id, client_id_len);
515                 } else if (otype == DHCPV6_OPT_SERVERID) {
516                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
517                                         &odata[-4], server_id, server_id_len);
518                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
519                                 sizeof(struct dhcpv6_auth_reconfigure)) {
520                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
521                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
522                                 continue;
523
524                         md5_state_t md5;
525                         uint8_t serverhash[16], secretbytes[16], hash[16];
526                         memcpy(serverhash, r->key, sizeof(serverhash));
527                         memset(r->key, 0, sizeof(r->key));
528                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
529
530                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
531                                 secretbytes[i] ^= 0x36;
532
533                         md5_init(&md5);
534                         md5_append(&md5, secretbytes, sizeof(secretbytes));
535                         md5_append(&md5, buf, len);
536                         md5_finish(&md5, hash);
537
538                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
539                                 secretbytes[i] ^= 0x36;
540                                 secretbytes[i] ^= 0x5c;
541                         }
542
543                         md5_init(&md5);
544                         md5_append(&md5, secretbytes, sizeof(secretbytes));
545                         md5_append(&md5, hash, 16);
546                         md5_finish(&md5, hash);
547
548                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
549                 }
550         }
551
552         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
553                 return false;
554
555         return clientid_ok && (serverid_ok || server_id_len == 0);
556 }
557
558
559 int dhcpv6_poll_reconfigure(void)
560 {
561         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
562         if (ret != -1)
563                 ret = dhcpv6_request(ret);
564
565         return ret;
566 }
567
568
569 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig, const int rc,
570                 const void *opt, const void *end)
571 {
572         // TODO: should verify the reconfigure message
573         uint16_t otype, olen;
574         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
575         dhcpv6_for_each_option(opt, end, otype, olen, odata)
576                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
577                                 odata[0] == DHCPV6_MSG_RENEW ||
578                                 odata[0] == DHCPV6_MSG_INFO_REQ))
579                         msg = odata[0];
580
581         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, rc, NULL, NULL);
582         return msg;
583 }
584
585
586 // Collect all advertised servers
587 static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
588                 const void *opt, const void *end)
589 {
590         uint16_t olen, otype;
591         uint8_t *odata, pref = 0;
592         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
593         bool have_na = false;
594         int have_pd = 0;
595
596         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
597                 if (orig == DHCPV6_MSG_SOLICIT &&
598                                 (otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA) &&
599                                 olen > sizeof(struct dhcpv6_ia_hdr)) {
600                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
601                         dhcpv6_parse_ia(ia_hdr, odata + olen + sizeof(*ia_hdr));
602                 }
603
604                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
605                         memcpy(cand.duid, odata, olen);
606                         cand.duid_len = olen;
607                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2) {
608                         int error = ((int)odata[0] << 8 | (int)odata[1]);
609
610                         switch (error) {
611                         case DHCPV6_NoPrefixAvail:
612                                 // Status code on global level
613                                 if (pd_mode == IA_MODE_FORCE)
614                                         return -1;
615                                 cand.preference -= 2000;
616                                 break;
617
618                         case DHCPV6_NoAddrsAvail:
619                                 // Status code on global level
620                                 if (na_mode == IA_MODE_FORCE)
621                                         return -1;
622                                 break;
623
624                         default :
625                                 break;
626                         }
627                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
628                                 cand.preference >= 0) {
629                         cand.preference = pref = odata[0];
630                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
631                         cand.wants_reconfigure = true;
632                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
633                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
634                         uint8_t *oend = odata + olen, *d;
635                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
636                                 if (otype == DHCPV6_OPT_IA_PREFIX && (olen + 4) >=
637                                                 (uint16_t)sizeof(struct dhcpv6_ia_prefix)) {
638                                         struct dhcpv6_ia_prefix *p = (struct dhcpv6_ia_prefix*)&d[-4];
639                                         have_pd = p->prefix;
640                                 }
641                         }
642                 } else if (otype == DHCPV6_OPT_IA_NA) {
643                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
644                         uint8_t *oend = odata + olen, *d;
645                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d)
646                                 if (otype == DHCPV6_OPT_IA_ADDR)
647                                         have_na = true;
648                 }
649         }
650
651         if ((!have_na && na_mode == IA_MODE_FORCE) ||
652                         (!have_pd && pd_mode == IA_MODE_FORCE))
653                 return -1;
654
655         if (na_mode != IA_MODE_NONE && !have_na) {
656                 cand.has_noaddravail = true;
657                 cand.preference -= 1000;
658         }
659
660         if (pd_mode != IA_MODE_NONE) {
661                 if (have_pd)
662                         cand.preference += 2000 + (128 - have_pd);
663                 else
664                         cand.preference -= 2000;
665         }
666
667         if (cand.duid_len > 0) {
668                 cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
669                 cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
670                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
671         }
672
673         if (orig == DHCPV6_MSG_SOLICIT) {
674                 odhcp6c_clear_state(STATE_IA_NA);
675                 odhcp6c_clear_state(STATE_IA_PD);
676         }
677
678         return (rc > 1 || (pref == 255 && cand.preference > 0)) ? 1 : -1;
679 }
680
681
682 static int dhcpv6_commit_advert(void)
683 {
684         size_t cand_len;
685         struct dhcpv6_server_cand *c = NULL, *cand =
686                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
687
688         bool retry = false;
689         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
690                 if (cand[i].has_noaddravail)
691                         retry = true; // We want to try again
692
693                 if (!c || c->preference < cand[i].preference)
694                         c = &cand[i];
695         }
696
697         if (retry && na_mode == IA_MODE_TRY) {
698                 // We give it a second try without the IA_NA
699                 na_mode = IA_MODE_NONE;
700                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
701         }
702
703         if (c) {
704                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
705                                 htons(c->duid_len)};
706                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
707                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
708                 accept_reconfig = c->wants_reconfigure;
709                 if (c->ia_na_len)
710                         odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
711                 if (c->ia_pd_len)
712                         odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
713         }
714
715         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
716                 free(cand[i].ia_na);
717                 free(cand[i].ia_pd);
718         }
719         odhcp6c_clear_state(STATE_SERVER_CAND);
720
721         if (!c)
722                 return -1;
723         else if ((request_prefix && c->ia_pd_len) || (na_mode != IA_MODE_NONE && c->ia_na_len))
724                 return DHCPV6_STATEFUL;
725         else
726                 return DHCPV6_STATELESS;
727 }
728
729
730 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig, const int rc,
731                 const void *opt, const void *end)
732 {
733         dhcpv6_handle_advert(orig, rc, opt, end);
734         if (dhcpv6_commit_advert() < 0) {
735                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, rc, NULL, NULL);
736                 return -1;
737         }
738
739         return dhcpv6_handle_reply(orig, rc, opt, end);
740 }
741
742
743 static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
744                 const void *opt, const void *end)
745 {
746         uint8_t *odata;
747         uint16_t otype, olen;
748         uint32_t refresh = UINT32_MAX;
749         int ret = 1;
750         bool handled_status_codes[_DHCPV6_Status_Max] = { false, };
751
752         odhcp6c_expire();
753
754         if (orig == DHCPV6_MSG_UNKNOWN) {
755                 static time_t last_update = 0;
756                 time_t now = odhcp6c_get_milli_time() / 1000;
757
758                 uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
759                 last_update = now;
760
761                 t1 -= elapsed;
762                 t2 -= elapsed;
763                 t3 -= elapsed;
764
765                 if (t1 < 0)
766                         t1 = 0;
767
768                 if (t2 < 0)
769                         t2 = 0;
770
771                 if (t3 < 0)
772                         t3 = 0;
773         }
774
775         if (orig == DHCPV6_MSG_REQUEST && !odhcp6c_is_bound()) {
776                 // Delete NA and PD we have in the state from the Advert
777                 odhcp6c_clear_state(STATE_IA_NA);
778                 odhcp6c_clear_state(STATE_IA_PD);
779         }
780
781         if (opt) {
782                 odhcp6c_clear_state(STATE_DNS);
783                 odhcp6c_clear_state(STATE_SEARCH);
784                 odhcp6c_clear_state(STATE_SNTP_IP);
785                 odhcp6c_clear_state(STATE_SNTP_FQDN);
786                 odhcp6c_clear_state(STATE_SIP_IP);
787                 odhcp6c_clear_state(STATE_SIP_FQDN);
788                 odhcp6c_clear_state(STATE_AFTR_NAME);
789         }
790
791         // Parse and find all matching IAs
792         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
793                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
794                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
795                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
796
797                         // Test ID
798                         if (ia_hdr->iaid != 1)
799                                 continue;
800
801                         uint16_t code = DHCPV6_Success;
802                         uint16_t stype, slen;
803                         uint8_t *sdata;
804                         // Get and handle status code
805                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
806                                         stype, slen, sdata) {
807                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2) {
808                                         uint8_t *mdata = (slen > 2) ? &sdata[2] : NULL;
809                                         uint16_t mlen = (slen > 2) ? slen - 2 : 0;
810
811                                         code = ((int)sdata[0]) << 8 | ((int)sdata[1]);
812
813                                         if (code == DHCPV6_Success)
814                                                 continue;
815
816                                         dhcpv6_handle_ia_status_code(orig, ia_hdr,
817                                                 code, mdata, mlen, handled_status_codes, &ret);
818
819
820                                         if (ret > 0)
821                                                 return ret;
822                                         break;
823                                 }
824                         }
825
826                         if (code != DHCPV6_Success)
827                                 continue;
828
829                         dhcpv6_parse_ia(ia_hdr, odata + olen + sizeof(*ia_hdr));
830                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2) {
831                         uint8_t *mdata = (olen > 2) ? &odata[2] : NULL;
832                         uint16_t mlen = (olen > 2) ? olen - 2 : 0;
833                         uint16_t code = ((int)odata[0]) << 8 | ((int)odata[1]);
834
835                         dhcpv6_handle_status_code(orig, code, mdata, mlen, &ret);
836                 }
837                 else if (otype == DHCPV6_OPT_DNS_SERVERS) {
838                         if (olen % 16 == 0)
839                                 odhcp6c_add_state(STATE_DNS, odata, olen);
840                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
841                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
842                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
843                         uint16_t stype, slen;
844                         uint8_t *sdata;
845                         // Test status and bail if error
846                         dhcpv6_for_each_option(odata, odata + olen,
847                                         stype, slen, sdata) {
848                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
849                                                 stype == NTP_SRV_ADDR))
850                                         odhcp6c_add_state(STATE_SNTP_IP,
851                                                         sdata, slen);
852                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
853                                         odhcp6c_add_state(STATE_SNTP_FQDN,
854                                                         sdata, slen);
855                         }
856                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
857                         if (olen == 16)
858                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
859                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
860                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
861                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
862                         refresh = ntohl(*((uint32_t*)odata));
863                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
864                                 sizeof(struct dhcpv6_auth_reconfigure)) {
865                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
866                         if (r->protocol == 3 && r->algorithm == 1 &&
867                                         r->reconf_type == 1)
868                                 memcpy(reconf_key, r->key, sizeof(r->key));
869                 } else if (otype == DHCPV6_OPT_AFTR_NAME && olen > 3) {
870                         size_t cur_len;
871                         odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
872                         if (cur_len == 0)
873                                 odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
874                 } else if (otype != DHCPV6_OPT_CLIENTID &&
875                                 otype != DHCPV6_OPT_SERVERID) {
876                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
877                                         &odata[-4], olen + 4);
878                 }
879         }
880
881         if (orig != DHCPV6_MSG_INFO_REQ) {
882                 // Update refresh timers if no fatal status code was received
883                 if ((ret > 0) && dhcpv6_calc_refresh_timers()) {
884                         switch (orig) {
885                         case DHCPV6_MSG_RENEW:
886                                 // Send further renews if T1 is not set
887                                 if (!t1)
888                                         ret = -1;
889                                 break;
890                         case DHCPV6_MSG_REBIND:
891                                 // Send further rebinds if T1 and T2 is not set
892                                 if (!t1 && !t2)
893                                         ret = -1;
894                                 break;
895
896                         default :
897                                 break;
898                         }
899                 }
900         }
901         else if (ret > 0)
902                 t1 = refresh;
903
904         return ret;
905 }
906
907
908 static int dhcpv6_parse_ia(void *opt, void *end)
909 {
910         struct dhcpv6_ia_hdr *ia_hdr = (struct dhcpv6_ia_hdr *)opt;
911         int parsed_ia = 0;
912         uint32_t t1, t2;
913         uint16_t otype, olen;
914         uint8_t *odata;
915
916         t1 = ntohl(ia_hdr->t1);
917         t2 = ntohl(ia_hdr->t2);
918
919         if (t1 > t2)
920                 return 0;
921
922         // Update address IA
923         dhcpv6_for_each_option(&ia_hdr[1], end, otype, olen, odata) {
924                 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0,
925                                 IN6ADDR_ANY_INIT, 0, 0, 0, 0, 0};
926
927                 if (otype == DHCPV6_OPT_IA_PREFIX) {
928                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
929                         if (olen + 4U < sizeof(*prefix))
930                                 continue;
931
932                         entry.valid = ntohl(prefix->valid);
933                         entry.preferred = ntohl(prefix->preferred);
934
935                         if (entry.preferred > entry.valid)
936                                 continue;
937
938                         entry.t1 = (t1 ? t1 : (entry.preferred != UINT32_MAX ? 0.5 * entry.preferred : UINT32_MAX));
939                         entry.t2 = (t2 ? t2 : (entry.preferred != UINT32_MAX ? 0.8 * entry.preferred : UINT32_MAX));
940                         if (entry.t1 > entry.t2)
941                                 entry.t1 = entry.t2;
942
943                         entry.length = prefix->prefix;
944                         entry.target = prefix->addr;
945                         uint16_t stype, slen;
946                         uint8_t *sdata;
947
948 #ifdef EXT_PREFIX_CLASS
949                         // Find prefix class, if any
950                         dhcpv6_for_each_option(&prefix[1], odata + olen,
951                                         stype, slen, sdata)
952                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
953                                         entry.class = sdata[0] << 8 | sdata[1];
954 #endif
955
956                         // Parse PD-exclude
957                         bool ok = true;
958                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
959                                         odata + olen, stype, slen, sdata) {
960                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
961                                         continue;
962
963                                 uint8_t elen = sdata[0];
964                                 if (elen > 64)
965                                         elen = 64;
966
967                                 if (elen <= 32 || elen <= entry.length) {
968                                         ok = false;
969                                         continue;
970                                 }
971
972
973                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
974                                 if (slen <= bytes) {
975                                         ok = false;
976                                         continue;
977                                 }
978
979                                 uint32_t exclude = 0;
980                                 do {
981                                         exclude = exclude << 8 | sdata[bytes];
982                                 } while (--bytes);
983
984                                 exclude >>= 8 - ((elen - entry.length) % 8);
985                                 exclude <<= 64 - elen;
986
987                                 // Abusing router & priority fields for exclusion
988                                 entry.router = entry.target;
989                                 entry.router.s6_addr32[1] |= htonl(exclude);
990                                 entry.priority = elen;
991                         }
992
993                         if (ok) {
994                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
995                                 parsed_ia++;
996                         }
997
998                         entry.priority = 0;
999                         memset(&entry.router, 0, sizeof(entry.router));
1000                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
1001                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
1002                         if (olen + 4U < sizeof(*addr))
1003                                 continue;
1004
1005                         entry.preferred = ntohl(addr->preferred);
1006                         entry.valid = ntohl(addr->valid);
1007
1008                         if (entry.preferred > entry.valid)
1009                                 continue;
1010
1011                         entry.t1 = (t1 ? t1 : (entry.preferred != UINT32_MAX ? 0.5 * entry.preferred : UINT32_MAX));
1012                         entry.t2 = (t2 ? t2 : (entry.preferred != UINT32_MAX ? 0.8 * entry.preferred : UINT32_MAX));
1013                         if (entry.t1 > entry.t2)
1014                                 entry.t1 = entry.t2;
1015
1016                         entry.length = 128;
1017                         entry.target = addr->addr;
1018
1019 #ifdef EXT_PREFIX_CLASS
1020                         uint16_t stype, slen;
1021                         uint8_t *sdata;
1022                         // Find prefix class, if any
1023                         dhcpv6_for_each_option(&addr[1], odata + olen,
1024                                         stype, slen, sdata)
1025                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
1026                                         entry.class = sdata[0] << 8 | sdata[1];
1027 #endif
1028
1029                         odhcp6c_update_entry(STATE_IA_NA, &entry);
1030                         parsed_ia++;
1031                 }
1032         }
1033         return parsed_ia;
1034 }
1035
1036
1037 static int dhcpv6_calc_refresh_timers(void)
1038 {
1039         struct odhcp6c_entry *e;
1040         size_t ia_na_entries, ia_pd_entries, i;
1041         int64_t l_t1 = UINT32_MAX, l_t2 = UINT32_MAX, l_t3 = 0;
1042
1043         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
1044         ia_na_entries /= sizeof(*e);
1045         for (i = 0; i < ia_na_entries; i++) {
1046                 if (e[i].t1 < l_t1)
1047                         l_t1 = e[i].t1;
1048
1049                 if (e[i].t2 < l_t2)
1050                         l_t2 = e[i].t2;
1051
1052                 if (e[i].valid > l_t3)
1053                         l_t3 = e[i].valid;
1054         }
1055
1056         e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
1057         ia_pd_entries /= sizeof(*e);
1058         for (i = 0; i < ia_pd_entries; i++) {
1059                 if (e[i].t1 < l_t1)
1060                         l_t1 = e[i].t1;
1061
1062                 if (e[i].t2 < l_t2)
1063                         l_t2 = e[i].t2;
1064
1065                 if (e[i].valid > l_t3)
1066                         l_t3 = e[i].valid;
1067         }
1068
1069         if (ia_pd_entries || ia_na_entries) {
1070                 t1 = l_t1;
1071                 t2 = l_t2;
1072                 t3 = l_t3;
1073         }
1074
1075         return (int)(ia_pd_entries + ia_na_entries);
1076 }
1077
1078
1079 static void dhcpv6_log_status_code(const uint16_t code, const char *scope,
1080                 const void *status_msg, const int len)
1081 {
1082         uint8_t buf[len + 3];
1083
1084         memset(buf, 0, sizeof(buf));
1085         if (len) {
1086                 buf[0] = '(';
1087                 memcpy(&buf[1], status_msg, len);
1088                 buf[len + 1] = ')';
1089         }
1090
1091         syslog(LOG_WARNING, "Server returned %s status %i %s",
1092                 scope, code, buf);
1093 }
1094
1095
1096 static void dhcpv6_handle_status_code(const enum dhcpv6_msg orig,
1097                 const uint16_t code, const void *status_msg, const int len,
1098                 int *ret)
1099 {
1100         dhcpv6_log_status_code(code, "message", status_msg, len);
1101
1102         switch (code) {
1103         case DHCPV6_UnspecFail:
1104                 // Generic failure
1105                 *ret = 0;
1106                 break;
1107
1108         case DHCPV6_UseMulticast:
1109                 // TODO handle multicast status code
1110                 break;
1111
1112         case DHCPV6_NoAddrsAvail:
1113         case DHCPV6_NoPrefixAvail:
1114                 if (orig == DHCPV6_MSG_REQUEST)
1115                         *ret = 0; // Failure
1116                 break;
1117
1118         default:
1119                 break;
1120         }
1121 }
1122
1123
1124 static void dhcpv6_handle_ia_status_code(const enum dhcpv6_msg orig,
1125                 const struct dhcpv6_ia_hdr *ia_hdr, const uint16_t code,
1126                 const void *status_msg, const int len,
1127                 bool handled_status_codes[_DHCPV6_Status_Max], int *ret)
1128 {
1129         dhcpv6_log_status_code(code, ia_hdr->type == DHCPV6_OPT_IA_NA ?
1130                 "IA_NA" : "IA_PD", status_msg, len);
1131
1132         switch (code) {
1133         case DHCPV6_NoBinding:
1134                 switch (orig) {
1135                 case DHCPV6_MSG_RENEW:
1136                 case DHCPV6_MSG_REBIND:
1137                         if ((*ret > 0) && !handled_status_codes[code])
1138                                 *ret = dhcpv6_request(DHCPV6_MSG_REQUEST);
1139                         break;
1140
1141                 default:
1142                         break;
1143                 }
1144                 break;
1145
1146         case DHCPV6_NoAddrsAvail:
1147         case DHCPV6_NoPrefixAvail:
1148                 switch (orig) {
1149                 case DHCPV6_MSG_REQUEST:
1150                         if (*ret != 0)
1151                                 *ret = 0;
1152                         break;
1153                 default:
1154                         break;
1155                 }
1156                 break;
1157
1158         case DHCPV6_NotOnLink:
1159                 // TODO handle not onlink in case of confirm
1160                 break;
1161
1162         default:
1163                 break;
1164         }
1165 }