Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  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
/*
 * services/cache/infra.h - infrastructure cache, server rtt and capabilities
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains the infrastructure cache, as well as rate limiting.
 * Note that there are two sorts of rate-limiting here:
 *  - Pre-cache, per-query rate limiting (query ratelimits)
 *  - Post-cache, per-domain name rate limiting (infra-ratelimits)
 */

#ifndef SERVICES_CACHE_INFRA_H
#define SERVICES_CACHE_INFRA_H
#include "util/storage/lruhash.h"
#include "util/storage/dnstree.h"
#include "util/rtt.h"
#include "util/netevent.h"
#include "util/data/msgreply.h"
struct slabhash;
struct config_file;

/**
 * Host information kept for every server, per zone.
 */
struct infra_key {
	/** the host address. */
	struct sockaddr_storage addr;
	/** length of addr. */
	socklen_t addrlen;
	/** zone name in wireformat */
	uint8_t* zonename;
	/** length of zonename */
	size_t namelen;
	/** hash table entry, data of type infra_data. */
	struct lruhash_entry entry;
};

/**
 * Host information encompasses host capabilities and retransmission timeouts.
 * And lameness information (notAuthoritative, noEDNS, Recursive)
 */
struct infra_data {
	/** TTL value for this entry. absolute time. */
	time_t ttl;

	/** time in seconds (absolute) when probing re-commences, 0 disabled */
	time_t probedelay;
	/** round trip times for timeout calculation */
	struct rtt_info rtt;

	/** edns version that the host supports, -1 means no EDNS */
	int edns_version;
	/** if the EDNS lameness is already known or not.
	 * EDNS lame is when EDNS queries or replies are dropped, 
	 * and cause a timeout */
	uint8_t edns_lame_known;

	/** is the host lame (does not serve the zone authoritatively),
	 * or is the host dnssec lame (does not serve DNSSEC data) */
	uint8_t isdnsseclame;
	/** is the host recursion lame (not AA, but RA) */
	uint8_t rec_lame;
	/** the host is lame (not authoritative) for A records */
	uint8_t lame_type_A;
	/** the host is lame (not authoritative) for other query types */
	uint8_t lame_other;

	/** timeouts counter for type A */
	uint8_t timeout_A;
	/** timeouts counter for type AAAA */
	uint8_t timeout_AAAA;
	/** timeouts counter for others */
	uint8_t timeout_other;
};

/**
 * Infra cache 
 */
struct infra_cache {
	/** The hash table with hosts */
	struct slabhash* hosts;
	/** TTL value for host information, in seconds */
	int host_ttl;
	/** hash table with query rates per name: rate_key, rate_data */
	struct slabhash* domain_rates;
	/** ratelimit settings for domains, struct domain_limit_data */
	rbtree_type domain_limits;
	/** hash table with query rates per client ip: ip_rate_key, ip_rate_data */
	struct slabhash* client_ip_rates;
};

/** ratelimit, unless overridden by domain_limits, 0 is off */
extern int infra_dp_ratelimit;

/**
 * ratelimit settings for domains
 */
struct domain_limit_data {
	/** key for rbtree, must be first in struct, name of domain */
	struct name_tree_node node;
	/** ratelimit for exact match with this name, -1 if not set */
	int lim;
	/** ratelimit for names below this name, -1 if not set */
	int below;
};

/**
 * key for ratelimit lookups, a domain name
 */
struct rate_key {
	/** lruhash key entry */
	struct lruhash_entry entry;
	/** domain name in uncompressed wireformat */
	uint8_t* name;
	/** length of name */
	size_t namelen;
};

/** ip ratelimit, 0 is off */
extern int infra_ip_ratelimit;

/**
 * key for ip_ratelimit lookups, a source IP.
 */
struct ip_rate_key {
	/** lruhash key entry */
	struct lruhash_entry entry;
	/** client ip information */
	struct sockaddr_storage addr;
	/** length of address */
	socklen_t addrlen;
};

/** number of seconds to track qps rate */
#define RATE_WINDOW 2

/**
 * Data for ratelimits per domain name
 * It is incremented when a non-cache-lookup happens for that domain name.
 * The name is the delegation point we have for the name.
 * If a new delegation point is found (a referral reply), the previous
 * delegation point is decremented, and the new one is charged with the query.
 */
struct rate_data {
	/** queries counted, for that second. 0 if not in use. */
	int qps[RATE_WINDOW];
	/** what the timestamp is of the qps array members, counter is
	 * valid for that timestamp.  Usually now and now-1. */
	time_t timestamp[RATE_WINDOW];
};

#define ip_rate_data rate_data

/** infra host cache default hash lookup size */
#define INFRA_HOST_STARTSIZE 32
/** bytes per zonename reserved in the hostcache, dnamelen(zonename.com.) */
#define INFRA_BYTES_NAME 14

/**
 * Create infra cache.
 * @param cfg: config parameters or NULL for defaults.
 * @return: new infra cache, or NULL.
 */
struct infra_cache* infra_create(struct config_file* cfg);

/**
 * Delete infra cache.
 * @param infra: infrastructure cache to delete.
 */
void infra_delete(struct infra_cache* infra);

/**
 * Adjust infra cache to use updated configuration settings.
 * This may clean the cache. Operates a bit like realloc.
 * There may be no threading or use by other threads.
 * @param infra: existing cache. If NULL a new infra cache is returned.
 * @param cfg: config options.
 * @return the new infra cache pointer or NULL on error.
 */
struct infra_cache* infra_adjust(struct infra_cache* infra, 
	struct config_file* cfg);

/**
 * Plain find infra data function (used by the the other functions)
 * @param infra: infrastructure cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: domain name of zone.
 * @param namelen: length of domain name.
 * @param wr: if true, writelock, else readlock.
 * @return the entry, could be expired (this is not checked) or NULL.
 */
struct lruhash_entry* infra_lookup_nottl(struct infra_cache* infra,
	struct sockaddr_storage* addr, socklen_t addrlen, uint8_t* name,
	size_t namelen, int wr);

/**
 * Find host information to send a packet. Creates new entry if not found.
 * Lameness is empty. EDNS is 0 (try with first), and rtt is returned for 
 * the first message to it.
 * Use this to send a packet only, because it also locks out others when
 * probing is restricted.
 * @param infra: infrastructure cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: domain name of zone.
 * @param namelen: length of domain name.
 * @param timenow: what time it is now.
 * @param edns_vs: edns version it supports, is returned.
 * @param edns_lame_known: if EDNS lame (EDNS is dropped in transit) has
 * 	already been probed, is returned.
 * @param to: timeout to use, is returned.
 * @return: 0 on error.
 */
int infra_host(struct infra_cache* infra, struct sockaddr_storage* addr, 
	socklen_t addrlen, uint8_t* name, size_t namelen,
	time_t timenow, int* edns_vs, uint8_t* edns_lame_known, int* to);

/**
 * Set a host to be lame for the given zone.
 * @param infra: infrastructure cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: domain name of zone apex.
 * @param namelen: length of domain name.
 * @param timenow: what time it is now.
 * @param dnsseclame: if true the host is set dnssec lame.
 *	if false, the host is marked lame (not serving the zone).
 * @param reclame: if true host is a recursor not AA server.
 *      if false, dnsseclame or marked lame.
 * @param qtype: the query type for which it is lame.
 * @return: 0 on error.
 */
int infra_set_lame(struct infra_cache* infra,
        struct sockaddr_storage* addr, socklen_t addrlen,
	uint8_t* name, size_t namelen, time_t timenow, int dnsseclame,
	int reclame, uint16_t qtype);

/**
 * Update rtt information for the host.
 * @param infra: infrastructure cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: zone name
 * @param namelen: zone name length
 * @param qtype: query type.
 * @param roundtrip: estimate of roundtrip time in milliseconds or -1 for 
 * 	timeout.
 * @param orig_rtt: original rtt for the query that timed out (roundtrip==-1).
 * 	ignored if roundtrip != -1.
 * @param timenow: what time it is now.
 * @return: 0 on error. new rto otherwise.
 */
int infra_rtt_update(struct infra_cache* infra, struct sockaddr_storage* addr,
	socklen_t addrlen, uint8_t* name, size_t namelen, int qtype,
	int roundtrip, int orig_rtt, time_t timenow);

/**
 * Update information for the host, store that a TCP transaction works.
 * @param infra: infrastructure cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: name of zone
 * @param namelen: length of name
 */
void infra_update_tcp_works(struct infra_cache* infra,
        struct sockaddr_storage* addr, socklen_t addrlen,
	uint8_t* name, size_t namelen);

/**
 * Update edns information for the host.
 * @param infra: infrastructure cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: name of zone
 * @param namelen: length of name
 * @param edns_version: the version that it publishes.
 * 	If it is known to support EDNS then no-EDNS is not stored over it.
 * @param timenow: what time it is now.
 * @return: 0 on error.
 */
int infra_edns_update(struct infra_cache* infra,
        struct sockaddr_storage* addr, socklen_t addrlen,
	uint8_t* name, size_t namelen, int edns_version, time_t timenow);

/**
 * Get Lameness information and average RTT if host is in the cache.
 * This information is to be used for server selection.
 * @param infra: infrastructure cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: zone name.
 * @param namelen: zone name length.
 * @param qtype: the query to be made.
 * @param lame: if function returns true, this returns lameness of the zone.
 * @param dnsseclame: if function returns true, this returns if the zone
 *	is dnssec-lame.
 * @param reclame: if function returns true, this is if it is recursion lame.
 * @param rtt: if function returns true, this returns avg rtt of the server.
 * 	The rtt value is unclamped and reflects recent timeouts.
 * @param timenow: what time it is now.
 * @return if found in cache, or false if not (or TTL bad).
 */
int infra_get_lame_rtt(struct infra_cache* infra,
        struct sockaddr_storage* addr, socklen_t addrlen, 
	uint8_t* name, size_t namelen, uint16_t qtype, 
	int* lame, int* dnsseclame, int* reclame, int* rtt, time_t timenow);

/**
 * Get additional (debug) info on timing.
 * @param infra: infra cache.
 * @param addr: host address.
 * @param addrlen: length of addr.
 * @param name: zone name
 * @param namelen: zone name length
 * @param rtt: the rtt_info is copied into here (caller alloced return struct).
 * @param delay: probe delay (if any).
 * @param timenow: what time it is now.
 * @param tA: timeout counter on type A.
 * @param tAAAA: timeout counter on type AAAA.
 * @param tother: timeout counter on type other.
 * @return TTL the infra host element is valid for. If -1: not found in cache.
 *	TTL -2: found but expired.
 */
long long infra_get_host_rto(struct infra_cache* infra,
        struct sockaddr_storage* addr, socklen_t addrlen, uint8_t* name,
	size_t namelen, struct rtt_info* rtt, int* delay, time_t timenow,
	int* tA, int* tAAAA, int* tother);

/**
 * Increment the query rate counter for a delegation point.
 * @param infra: infra cache.
 * @param name: zone name
 * @param namelen: zone name length
 * @param timenow: what time it is now.
 * @param qinfo: for logging, query name.
 * @param replylist: for logging, querier's address (if any).
 * @return 1 if it could be incremented. 0 if the increment overshot the
 * ratelimit or if in the previous second the ratelimit was exceeded.
 * Failures like alloc failures are not returned (probably as 1).
 */
int infra_ratelimit_inc(struct infra_cache* infra, uint8_t* name,
	size_t namelen, time_t timenow, struct query_info* qinfo,
	struct comm_reply* replylist);

/**
 * Decrement the query rate counter for a delegation point.
 * Because the reply received for the delegation point was pleasant,
 * we do not charge this delegation point with it (i.e. it was a referral).
 * Should call it with same second as when inc() was called.
 * @param infra: infra cache.
 * @param name: zone name
 * @param namelen: zone name length
 * @param timenow: what time it is now.
 */
void infra_ratelimit_dec(struct infra_cache* infra, uint8_t* name,
	size_t namelen, time_t timenow);

/**
 * See if the query rate counter for a delegation point is exceeded.
 * So, no queries are going to be allowed.
 * @param infra: infra cache.
 * @param name: zone name
 * @param namelen: zone name length
 * @param timenow: what time it is now.
 * @return true if exceeded.
 */
int infra_ratelimit_exceeded(struct infra_cache* infra, uint8_t* name,
	size_t namelen, time_t timenow);

/** find the maximum rate stored, not too old. 0 if no information. */
int infra_rate_max(void* data, time_t now);

/** find the ratelimit in qps for a domain. 0 if no limit for domain. */
int infra_find_ratelimit(struct infra_cache* infra, uint8_t* name,
	size_t namelen);

/** Update query ratelimit hash and decide
 *  whether or not a query should be dropped.
 *  @param infra: infra cache
 *  @param repinfo: information about client
 *  @param timenow: what time it is now.
 *  @param buffer: with query for logging.
 *  @return 1 if it could be incremented. 0 if the increment overshot the
 *  ratelimit and the query should be dropped. */
int infra_ip_ratelimit_inc(struct infra_cache* infra,
	struct comm_reply* repinfo, time_t timenow,
	struct sldns_buffer* buffer);

/**
 * Get memory used by the infra cache.
 * @param infra: infrastructure cache.
 * @return memory in use in bytes.
 */
size_t infra_get_mem(struct infra_cache* infra);

/** calculate size for the hashtable, does not count size of lameness,
 * so the hashtable is a fixed number of items */
size_t infra_sizefunc(void* k, void* d);

/** compare two addresses, returns -1, 0, or +1 */
int infra_compfunc(void* key1, void* key2);

/** delete key, and destroy the lock */
void infra_delkeyfunc(void* k, void* arg);

/** delete data and destroy the lameness hashtable */
void infra_deldatafunc(void* d, void* arg);

/** calculate size for the hashtable */
size_t rate_sizefunc(void* k, void* d);

/** compare two names, returns -1, 0, or +1 */
int rate_compfunc(void* key1, void* key2);

/** delete key, and destroy the lock */
void rate_delkeyfunc(void* k, void* arg);

/** delete data */
void rate_deldatafunc(void* d, void* arg);

/* calculate size for the client ip hashtable */
size_t ip_rate_sizefunc(void* k, void* d);

/* compare two addresses */
int ip_rate_compfunc(void* key1, void* key2);

/* delete key, and destroy the lock */
void ip_rate_delkeyfunc(void* d, void* arg);

/* delete data */
#define ip_rate_deldatafunc rate_deldatafunc

#endif /* SERVICES_CACHE_INFRA_H */