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96779587 CH |
1 | /* |
2 | The software in this package is distributed under the GNU General | |
3 | Public License version 2 (with a special exception described below). | |
4 | ||
5 | A copy of GNU General Public License (GPL) is included in this distribution, | |
6 | in the file COPYING.GPL. | |
7 | ||
8 | As a special exception, if other files instantiate templates or use macros | |
9 | or inline functions from this file, or you compile this file and link it | |
10 | with other works to produce a work based on this file, this file | |
11 | does not by itself cause the resulting work to be covered | |
12 | by the GNU General Public License. | |
13 | ||
14 | However the source code for this file must still be made available | |
15 | in accordance with section (3) of the GNU General Public License. | |
16 | ||
17 | This exception does not invalidate any other reasons why a work based | |
18 | on this file might be covered by the GNU General Public License. | |
19 | ||
20 | Christian Herdtweck, Intra2net AG 2015 | |
21 | */ | |
22 | ||
c5b4902d | 23 | #include "dns/dnscache.h" |
96779587 | 24 | |
f636ba88 | 25 | #include <sstream> |
946356e1 | 26 | #include <fstream> |
96779587 | 27 | #include <logfunc.hpp> |
946356e1 | 28 | #include <filefunc.hxx> // I2n::file_exists |
e18c1337 | 29 | #include <boost/foreach.hpp> |
96779587 | 30 | #include <boost/bind.hpp> |
96779587 | 31 | #include <boost/asio/placeholders.hpp> |
946356e1 CH |
32 | #include <boost/serialization/serialization.hpp> |
33 | #include <boost/serialization/map.hpp> | |
34 | #include <boost/serialization/string.hpp> | |
35 | #include <boost/serialization/vector.hpp> | |
36 | #include <boost/archive/xml_oarchive.hpp> | |
37 | #include <boost/archive/xml_iarchive.hpp> | |
96779587 | 38 | |
dbe986b9 CH |
39 | #include "dns/dnsmaster.h" |
40 | ||
96779587 CH |
41 | using boost::bind; |
42 | using boost::posix_time::seconds; | |
43 | using I2n::Logger::GlobalLogger; | |
44 | ||
8d26221d | 45 | |
96779587 CH |
46 | namespace Config |
47 | { | |
77319ba8 CH |
48 | const int SAVE_TIMER_SECONDS = 60; |
49 | const int CACHE_TIME_WARP_THRESH_HOURS = 24; | |
4e691eb0 | 50 | const int CACHE_REMOVE_OUTDATED_DAYS = 60; |
96779587 CH |
51 | } |
52 | ||
8d26221d | 53 | |
f833126b CH |
54 | // ----------------------------------------------------------------------------- |
55 | // DNS Cache constructor / destructor | |
56 | // ----------------------------------------------------------------------------- | |
57 | ||
8d26221d CH |
58 | const string DnsCache::DoNotUseCacheFile = "do not use cache file!"; |
59 | ||
96779587 | 60 | DnsCache::DnsCache(const IoServiceItem &io_serv, |
f833126b CH |
61 | const std::string &cache_file, |
62 | const uint32_t min_time_between_resolves) | |
ad83004d CH |
63 | : IpCache() |
64 | , CnameCache() | |
96779587 CH |
65 | , SaveTimer( *io_serv ) |
66 | , CacheFile( cache_file ) | |
67 | , HasChanged( false ) | |
f833126b | 68 | , MinTimeBetweenResolves( min_time_between_resolves ) |
96779587 CH |
69 | { |
70 | // load cache from file | |
71 | load_from_cachefile(); | |
72 | ||
73 | // schedule next save | |
77319ba8 | 74 | (void) SaveTimer.expires_from_now( seconds( Config::SAVE_TIMER_SECONDS ) ); |
96779587 CH |
75 | SaveTimer.async_wait( bind( &DnsCache::schedule_save, this, |
76 | boost::asio::placeholders::error ) ); | |
77 | } | |
78 | ||
79 | ||
80 | DnsCache::~DnsCache() | |
81 | { | |
26b0f687 | 82 | GlobalLogger.info() << "DnsCache: being destructed"; |
e91538f0 | 83 | |
96779587 CH |
84 | // save one last time without re-scheduling the next save |
85 | save_to_cachefile(); | |
86 | ||
87 | // cancel save timer | |
88 | SaveTimer.cancel(); | |
89 | } | |
90 | ||
91 | ||
f833126b CH |
92 | // ----------------------------------------------------------------------------- |
93 | // LOAD / SAVE | |
94 | // ----------------------------------------------------------------------------- | |
95 | ||
96779587 CH |
96 | void DnsCache::schedule_save(const boost::system::error_code &error) |
97 | { | |
96779587 CH |
98 | if ( error == boost::asio::error::operation_aborted ) // cancelled |
99 | { | |
49b82a1d CH |
100 | GlobalLogger.info() << "DnsCache: SaveTimer was cancelled " |
101 | << "--> no save and no re-schedule of saving!"; | |
96779587 CH |
102 | return; |
103 | } | |
104 | else if (error) | |
105 | { | |
49b82a1d CH |
106 | GlobalLogger.info() << "DnsCache: Received error " << error |
107 | << " in schedule_save " | |
108 | << "--> no save now but re-schedule saving"; | |
96779587 CH |
109 | } |
110 | else | |
111 | save_to_cachefile(); | |
112 | ||
113 | // schedule next save | |
77319ba8 | 114 | (void) SaveTimer.expires_from_now( seconds( Config::SAVE_TIMER_SECONDS ) ); |
96779587 CH |
115 | SaveTimer.async_wait( bind( &DnsCache::schedule_save, this, |
116 | boost::asio::placeholders::error ) ); | |
117 | } | |
118 | ||
119 | void DnsCache::save_to_cachefile() | |
120 | { | |
121 | if (!HasChanged) | |
ad83004d | 122 | GlobalLogger.info() << "DnsCache: skip saving because has not changed"; |
946356e1 | 123 | else if (CacheFile.empty()) |
49b82a1d | 124 | GlobalLogger.info() |
ad83004d | 125 | << "DnsCache: skip saving because file name empty!"; |
8d26221d | 126 | else if (CacheFile == DoNotUseCacheFile) |
26b0f687 CH |
127 | GlobalLogger.info() << "DnsCache: configured not to use cache file"; |
128 | else | |
946356e1 | 129 | { |
26b0f687 CH |
130 | try |
131 | { | |
77319ba8 CH |
132 | // remember time of save |
133 | std::string cache_save_time_str = boost::posix_time::to_iso_string( | |
134 | boost::posix_time::second_clock::universal_time() ); | |
135 | ||
26b0f687 CH |
136 | std::ofstream ofs( CacheFile.c_str() ); |
137 | boost::archive::xml_oarchive oa(ofs); | |
26b0f687 CH |
138 | oa & BOOST_SERIALIZATION_NVP(IpCache); |
139 | oa & BOOST_SERIALIZATION_NVP(CnameCache); | |
77319ba8 | 140 | oa & BOOST_SERIALIZATION_NVP(cache_save_time_str); |
8d26221d CH |
141 | GlobalLogger.info() << "DnsCache: saved to cache file " |
142 | << CacheFile; | |
26b0f687 CH |
143 | |
144 | HasChanged = false; | |
145 | } | |
146 | catch (std::exception &exc) | |
147 | { | |
c1abff61 | 148 | GlobalLogger.warning() << "DnsCache: Saving failed: " << exc.what(); |
26b0f687 | 149 | } |
946356e1 | 150 | } |
96779587 CH |
151 | } |
152 | ||
96779587 CH |
153 | void DnsCache::load_from_cachefile() |
154 | { | |
946356e1 | 155 | if (CacheFile.empty()) |
49b82a1d | 156 | GlobalLogger.info() |
8d26221d CH |
157 | << "DnsCache: cannot load because cache file name is empty!"; |
158 | else if (CacheFile == DoNotUseCacheFile) | |
26b0f687 | 159 | GlobalLogger.info() << "DnsCache: configured not to use cache file"; |
946356e1 | 160 | else if ( !I2n::file_exists(CacheFile) ) |
ad83004d | 161 | GlobalLogger.warning() << "DnsCache: cannot load because cache file " |
946356e1 | 162 | << CacheFile << " does not exist!"; |
26b0f687 | 163 | else |
946356e1 | 164 | { |
26b0f687 CH |
165 | try |
166 | { | |
167 | std::ifstream ifs( CacheFile.c_str() ); | |
168 | boost::archive::xml_iarchive ia(ifs); | |
946356e1 | 169 | |
77319ba8 CH |
170 | std::string cache_save_time_str; |
171 | ||
26b0f687 CH |
172 | ia & BOOST_SERIALIZATION_NVP(IpCache); |
173 | ia & BOOST_SERIALIZATION_NVP(CnameCache); | |
77319ba8 CH |
174 | ia & BOOST_SERIALIZATION_NVP(cache_save_time_str); |
175 | ||
176 | boost::posix_time::ptime cache_save_time | |
177 | = boost::posix_time::from_iso_string(cache_save_time_str); | |
26b0f687 | 178 | GlobalLogger.info() << "DnsCache: loaded from file " << CacheFile; |
77319ba8 CH |
179 | |
180 | check_timestamps(cache_save_time); | |
26b0f687 CH |
181 | } |
182 | catch (boost::archive::archive_exception &exc) | |
183 | { | |
8d26221d CH |
184 | GlobalLogger.warning() |
185 | << "DnsCache: archive exception loading from " << CacheFile | |
186 | << ": " << exc.what(); | |
26b0f687 CH |
187 | } |
188 | catch (std::exception &exc) | |
189 | { | |
190 | GlobalLogger.warning() << "DnsCache: exception while loading from " | |
191 | << CacheFile << ": " << exc.what(); | |
192 | } | |
946356e1 | 193 | } |
96779587 CH |
194 | } |
195 | ||
26b0f687 | 196 | |
77319ba8 CH |
197 | /** |
198 | * @brief check that loaded cache really is from the past | |
199 | * | |
200 | * Added this to avoid trouble in case the system time is changed into the past. | |
201 | * In that cast would have TTLs here in cache that are valid much too long. | |
202 | * | |
203 | * Therefore check SaveCacheTime and if that is in the future, set all TTLs to 0 | |
204 | * | |
205 | * @returns true if had to re-set timestamps | |
206 | */ | |
207 | bool DnsCache::check_timestamps(const boost::posix_time::ptime &cache_save_time) | |
208 | { | |
209 | // check if CacheSaveTime is in the future | |
210 | boost::posix_time::ptime now | |
211 | = boost::posix_time::second_clock::universal_time() | |
212 | + boost::posix_time::hours( Config::CACHE_TIME_WARP_THRESH_HOURS ); | |
213 | if (now > cache_save_time) | |
214 | { // Cache was saved in the past -- everything alright | |
215 | return false; | |
216 | } | |
217 | ||
218 | GlobalLogger.warning() << "DnsCache: loaded cache from the future (saved " | |
219 | << cache_save_time << ")! Resetting all TTLs to 0."; | |
220 | ||
221 | // reset TTLs in IP cache | |
222 | BOOST_FOREACH( const ip_map_type::value_type key_and_ip, IpCache ) | |
223 | { | |
224 | HostAddressVec addr_reset; | |
225 | BOOST_FOREACH( HostAddress address, key_and_ip.second ) | |
226 | addr_reset.push_back( HostAddress( address.get_ip(), 0 ) ); | |
227 | IpCache[key_and_ip.first] = addr_reset; | |
228 | } | |
229 | ||
230 | // reset TTLs in CNAME cache | |
231 | BOOST_FOREACH( const cname_map_type::value_type key_and_cname, CnameCache ) | |
232 | CnameCache[key_and_cname.first] = Cname( key_and_cname.second.Host, | |
233 | TimeToLive(0) ); | |
234 | ||
235 | return true; | |
236 | } | |
237 | ||
238 | ||
f833126b CH |
239 | // ----------------------------------------------------------------------------- |
240 | // UPDATE | |
241 | // ----------------------------------------------------------------------------- | |
242 | ||
8f00b3df CH |
243 | /* |
244 | * warn if hostname is empty and remove trailing dot | |
245 | * also warn if protocol is neither IPv4 nor IPv6 | |
246 | */ | |
247 | ip_map_key_type DnsCache::key_for_ips(const std::string &hostname, | |
248 | const DnsIpProtocol &protocol) const | |
96779587 | 249 | { |
26b0f687 CH |
250 | if (hostname.empty()) |
251 | { | |
49b82a1d | 252 | GlobalLogger.info() << "DnsCache: empty host!"; |
8f00b3df CH |
253 | return ip_map_key_type("", DNS_IPALL); |
254 | } | |
255 | if (protocol == DNS_IPALL) | |
256 | { | |
257 | GlobalLogger.info() << "DnsCache: neither IPv4 nor v6!"; | |
258 | return ip_map_key_type("", DNS_IPALL); | |
26b0f687 CH |
259 | } |
260 | ||
261 | // check whether last character is a dot | |
262 | if (hostname.rfind('.') == hostname.length()-1) | |
8f00b3df CH |
263 | return ip_map_key_type( hostname.substr(0, hostname.length()-1), |
264 | protocol ); | |
26b0f687 | 265 | else |
8f00b3df CH |
266 | return ip_map_key_type( hostname, |
267 | protocol ); | |
96779587 CH |
268 | } |
269 | ||
270 | ||
ad83004d | 271 | void DnsCache::update(const std::string &hostname, |
8f00b3df | 272 | const DnsIpProtocol &protocol, |
26b0f687 | 273 | const HostAddressVec &new_ips) |
ad83004d | 274 | { |
8f00b3df CH |
275 | // check for valid input arguments |
276 | ip_map_key_type key = key_for_ips(hostname, protocol); | |
277 | if ( key.first.empty() ) | |
278 | return; | |
279 | ||
280 | // ensure that there is never IP and CNAME for the same host | |
26b0f687 | 281 | if ( !get_cname(hostname).Host.empty() ) |
8f00b3df CH |
282 | { |
283 | GlobalLogger.info() << "DnsCache: Saving IPs for " << key.first | |
26b0f687 CH |
284 | << " removes CNAME to " << get_cname(hostname).Host << "!"; |
285 | update(hostname, Cname()); // overwrite with "empty" cname | |
286 | } | |
8f00b3df | 287 | |
f833126b CH |
288 | // ensure min ttl of MinTimeBetweenResolves |
289 | HostAddressVec ips_checked; | |
290 | BOOST_FOREACH( const HostAddress &addr, new_ips ) | |
291 | { | |
292 | if ( addr.get_ttl().get_value() < MinTimeBetweenResolves ) | |
293 | { | |
294 | GlobalLogger.info() << "DnsCache: Correcting TTL of IP for " | |
8f00b3df | 295 | << key.first << " from " << addr.get_ttl().get_value() << "s to " |
f833126b CH |
296 | << MinTimeBetweenResolves << "s because was too short"; |
297 | ips_checked.push_back( HostAddress( addr.get_ip(), | |
298 | MinTimeBetweenResolves) ); | |
299 | } | |
300 | else | |
301 | ips_checked.push_back(addr); | |
302 | } | |
303 | ||
8f00b3df | 304 | // write IPs into one log line |
f636ba88 | 305 | stringstream log_temp; |
8f00b3df | 306 | log_temp << "DnsCache: update IPs for " << key.first << " to " |
f636ba88 CH |
307 | << ips_checked.size() << "-list: "; |
308 | BOOST_FOREACH( const HostAddress &ip, ips_checked ) | |
309 | log_temp << ip.get_ip() << ", "; | |
310 | GlobalLogger.notice() << log_temp.str(); | |
f833126b CH |
311 | |
312 | IpCache[key] = ips_checked; | |
ad83004d CH |
313 | HasChanged = true; |
314 | } | |
315 | ||
316 | ||
8f00b3df CH |
317 | /* |
318 | * warn if hostname is empty and remove trailing dot | |
319 | */ | |
320 | cname_map_key_type DnsCache::key_for_cname(const std::string &hostname) const | |
321 | { | |
322 | if (hostname.empty()) | |
323 | { | |
324 | GlobalLogger.info() << "DnsCache: empty host!"; | |
325 | return ""; | |
326 | } | |
327 | ||
328 | // check whether last character is a dot | |
329 | if (hostname.rfind('.') == hostname.length()-1) | |
330 | return hostname.substr(0, hostname.length()-1); | |
331 | else | |
332 | return hostname; | |
333 | } | |
334 | ||
335 | ||
dbe986b9 | 336 | void DnsCache::update(const std::string &hostname, |
26b0f687 | 337 | const Cname &cname) |
ad83004d | 338 | { |
8f00b3df CH |
339 | // check for valid input arguments |
340 | cname_map_key_type key = key_for_cname(hostname); | |
341 | if ( key.empty() ) | |
342 | return; | |
343 | ||
344 | // ensure that there is never IP and CNAME for the same host | |
345 | int n_ips = get_ips(hostname, DNS_IPv4).size() | |
346 | + get_ips(hostname, DNS_IPv6).size(); | |
347 | if ( n_ips > 0 ) | |
348 | { | |
349 | GlobalLogger.info() << "DnsCache: Saving IPs for " << key | |
350 | << " removes CNAME to " << get_cname(hostname).Host << "!"; | |
49b82a1d | 351 | GlobalLogger.info() << "DnsCache: Saving CNAME for " << key |
8f00b3df CH |
352 | << " removes " << n_ips << " IPs for same host!"; |
353 | update(hostname, DNS_IPv4, HostAddressVec()); | |
354 | update(hostname, DNS_IPv6, HostAddressVec()); | |
ad83004d | 355 | } |
26b0f687 | 356 | |
8f00b3df CH |
357 | // remove possible trailing dot from cname's target host |
358 | Cname to_save = Cname(key_for_cname(cname.Host), // implicit cast to string | |
26b0f687 CH |
359 | cname.Ttl); |
360 | ||
f833126b CH |
361 | // ensure min ttl of MinTimeBetweenResolves |
362 | if ( to_save.Ttl.get_value() < MinTimeBetweenResolves ) | |
363 | { | |
364 | GlobalLogger.info() << "DnsCache: Correcting TTL of CNAME of " | |
8f00b3df | 365 | << key << " from " << to_save.Ttl.get_value() << "s to " |
f833126b CH |
366 | << MinTimeBetweenResolves << "s because was too short"; |
367 | to_save.Ttl = TimeToLive(MinTimeBetweenResolves); | |
368 | } | |
369 | ||
f636ba88 | 370 | GlobalLogger.notice() << "DnsCache: update CNAME for " << key |
8f00b3df | 371 | << " to " << to_save.Host; |
26b0f687 CH |
372 | CnameCache[key] = to_save; |
373 | HasChanged = true; | |
ad83004d CH |
374 | } |
375 | ||
376 | ||
f833126b CH |
377 | // ----------------------------------------------------------------------------- |
378 | // RETRIEVAL | |
379 | // ----------------------------------------------------------------------------- | |
380 | ||
23f51766 CH |
381 | /** |
382 | * @returns empty list if no (up to date) ips for hostname in cache | |
383 | */ | |
dbe986b9 | 384 | HostAddressVec DnsCache::get_ips(const std::string &hostname, |
8f00b3df | 385 | const DnsIpProtocol &protocol, |
dbe986b9 | 386 | const bool check_up_to_date) |
96779587 | 387 | { |
8f00b3df | 388 | ip_map_key_type key = key_for_ips(hostname, protocol); |
26b0f687 | 389 | HostAddressVec result = IpCache[key]; |
dbe986b9 CH |
390 | if (check_up_to_date) |
391 | { | |
392 | HostAddressVec result_up_to_date; | |
23f51766 CH |
393 | uint32_t threshold = static_cast<uint32_t>( |
394 | DnsMaster::get_instance()->get_resolved_ip_ttl_threshold() ); | |
26b0f687 | 395 | uint32_t updated_ttl; |
dbe986b9 CH |
396 | BOOST_FOREACH( const HostAddress &addr, result ) |
397 | { | |
26b0f687 CH |
398 | updated_ttl = addr.get_ttl().get_updated_value(); |
399 | if (updated_ttl > threshold) | |
dbe986b9 | 400 | result_up_to_date.push_back(addr); |
26b0f687 CH |
401 | else |
402 | GlobalLogger.debug() << "DnsCache: do not return " | |
403 | << addr.get_ip().to_string() << " since TTL " | |
404 | << updated_ttl << "s is out of date (thresh=" | |
405 | << threshold << "s)"; | |
dbe986b9 | 406 | } |
dbe986b9 CH |
407 | result = result_up_to_date; |
408 | } | |
8f00b3df | 409 | /*GlobalLogger.debug() << "DnsCache: request IPs for " << key.first |
26b0f687 CH |
410 | << " --> " << result.size() << "-list"; |
411 | BOOST_FOREACH( const HostAddress &addr, result ) | |
412 | GlobalLogger.debug() << "DnsCache: " << addr.get_ip().to_string() | |
fd62d09f | 413 | << " (TTL " << addr.get_ttl().get_updated_value() |
2a4dde8b | 414 | << "s)"; */ |
dbe986b9 | 415 | return result; |
96779587 CH |
416 | } |
417 | ||
23f51766 CH |
418 | /** |
419 | * @returns empty cname if no (up to date cname) for hostname in cache | |
420 | */ | |
421 | Cname DnsCache::get_cname(const std::string &hostname, | |
422 | const bool check_up_to_date) | |
ad83004d | 423 | { |
8f00b3df | 424 | cname_map_key_type key = key_for_cname(hostname); |
26b0f687 | 425 | Cname result_obj = CnameCache[key]; |
2a4dde8b | 426 | /*GlobalLogger.debug() << "DnsCache: request CNAME for " << key |
fd62d09f | 427 | << " --> \"" << result_obj.Host << "\" (TTL " |
2a4dde8b | 428 | << result_obj.Ttl.get_updated_value() << "s)";*/ |
23f51766 CH |
429 | if (result_obj.Host.empty()) |
430 | return result_obj; | |
431 | ||
432 | else if (check_up_to_date) | |
dbe986b9 | 433 | { |
26b0f687 CH |
434 | if ( result_obj.Ttl.get_updated_value() > static_cast<uint32_t>( |
435 | DnsMaster::get_instance()->get_resolved_ip_ttl_threshold()) ) | |
23f51766 | 436 | return result_obj; |
dbe986b9 CH |
437 | else |
438 | { | |
23f51766 CH |
439 | GlobalLogger.debug() << "DnsCache: CNAME is out of date"; |
440 | return Cname(); // same as if there was no cname for hostname | |
dbe986b9 CH |
441 | } |
442 | } | |
443 | else | |
23f51766 | 444 | return result_obj; |
ad83004d CH |
445 | } |
446 | ||
dbe986b9 CH |
447 | // underlying assumption in this function: for a hostname, the cache has either |
448 | // a list of IPs saved or a cname saved, but never both | |
449 | HostAddressVec DnsCache::get_ips_recursive(const std::string &hostname, | |
8f00b3df | 450 | const DnsIpProtocol &protocol, |
dbe986b9 | 451 | const bool check_up_to_date) |
e18c1337 CH |
452 | { |
453 | std::string current_host = hostname; | |
23f51766 | 454 | Cname current_cname; |
8f00b3df | 455 | HostAddressVec result = get_ips(current_host, protocol, check_up_to_date); |
dbe986b9 | 456 | int n_recursions = 0; |
23f51766 | 457 | uint32_t min_cname_ttl = 0xffff; // largest possible unsigned 4-byte value |
cd71d095 CH |
458 | int max_recursion_count = DnsMaster::get_instance() |
459 | ->get_max_recursion_count(); | |
e18c1337 CH |
460 | while ( result.empty() ) |
461 | { | |
23f51766 | 462 | current_cname = get_cname(current_host, check_up_to_date); |
8d26221d | 463 | if (current_cname.Host.empty()) |
8f00b3df CH |
464 | break; // no ips (since result.empty()) and no cname |
465 | // --> will return empty result | |
8d26221d | 466 | |
8f00b3df | 467 | current_host = current_cname.Host; |
cd71d095 | 468 | if (++n_recursions >= max_recursion_count) |
dbe986b9 | 469 | { |
49b82a1d CH |
470 | GlobalLogger.info() << "DnsCache: reached recursion limit of " |
471 | << n_recursions << " in recursive IP retrieval of " | |
472 | << hostname << "!"; | |
dbe986b9 CH |
473 | break; |
474 | } | |
e18c1337 | 475 | else |
23f51766 | 476 | { |
fd62d09f CH |
477 | min_cname_ttl = min(min_cname_ttl, |
478 | current_cname.Ttl.get_updated_value()); | |
8f00b3df | 479 | result = get_ips(current_host, protocol, check_up_to_date); |
23f51766 CH |
480 | } |
481 | } | |
482 | ||
483 | GlobalLogger.debug() << "DnsCache: recursive IP retrieval resulted in " | |
484 | << result.size() << "-list after " << n_recursions | |
485 | << " recursions"; | |
486 | ||
487 | // adjust ttl to min of ttl and min_cname_ttl | |
488 | if (n_recursions > 0) | |
489 | { | |
490 | TimeToLive cname_ttl(min_cname_ttl); | |
491 | ||
492 | BOOST_FOREACH( HostAddress &addr, result ) | |
493 | { | |
fd62d09f | 494 | if (addr.get_ttl().get_updated_value() > min_cname_ttl) |
8d26221d | 495 | { |
2a4dde8b | 496 | //GlobalLogger.debug() << "DnsCache: using shorter CNAME TTL"; |
23f51766 | 497 | addr.set_ttl(cname_ttl); |
8d26221d | 498 | } |
23f51766 | 499 | } |
e18c1337 | 500 | } |
23f51766 | 501 | |
e18c1337 CH |
502 | return result; |
503 | } | |
ad83004d | 504 | |
23f51766 | 505 | /** |
9d1b2726 CH |
506 | * from a list of CNAMEs find the first one that is out of date or empty |
507 | * | |
508 | * returns the hostname that is out of date or empty if all CNAMEs are | |
509 | * up-to-date | |
23f51766 CH |
510 | * |
511 | * required in ResolverBase::get_skipper | |
23f51766 CH |
512 | */ |
513 | std::string DnsCache::get_first_outdated_cname(const std::string &hostname, | |
514 | const uint32_t ttl_thresh) | |
515 | { | |
8d26221d | 516 | std::string first_outdated = hostname; |
23f51766 CH |
517 | Cname cname; |
518 | int n_recursions = 0; | |
cd71d095 CH |
519 | int max_recursion_count = DnsMaster::get_instance() |
520 | ->get_max_recursion_count(); | |
23f51766 CH |
521 | while (true) |
522 | { | |
cd71d095 | 523 | if (++n_recursions >= max_recursion_count) |
23f51766 | 524 | { |
49b82a1d CH |
525 | GlobalLogger.info() << "DnsCache: reached recursion limit of " |
526 | << n_recursions << " in search of outdated CNAMEs for " | |
527 | << hostname << "!"; | |
9d1b2726 CH |
528 | return first_outdated; // not really out of date but currently |
529 | } // our best guess | |
23f51766 | 530 | |
8d26221d CH |
531 | cname = get_cname(first_outdated); |
532 | if (cname.Host.empty()) | |
9d1b2726 CH |
533 | // reached end of cname list --> everything was up-to-date |
534 | return ""; | |
23f51766 CH |
535 | else if (cname.Ttl.get_updated_value() > ttl_thresh) |
536 | // cname is up to date --> continue looking | |
8d26221d | 537 | first_outdated = cname.Host; |
23f51766 | 538 | else |
9d1b2726 CH |
539 | // cname is out of date --> return its target |
540 | return cname.Host; | |
23f51766 | 541 | } |
9d1b2726 CH |
542 | // reach this point only if cname chain does not end with an IP |
543 | // --> all are up-to-date | |
544 | return ""; | |
23f51766 | 545 | } |
e638894d CH |
546 | |
547 | std::string DnsCache::get_cname_chain_str(const std::string &hostname) | |
548 | { | |
549 | std::stringstream temp; | |
550 | temp << hostname; | |
551 | std::string current_host = hostname; | |
552 | Cname current_cname; | |
553 | int n_recursions = 0; | |
554 | int max_recursion_count = DnsMaster::get_instance() | |
555 | ->get_max_recursion_count(); | |
556 | while (true) | |
557 | { | |
558 | if (n_recursions >= max_recursion_count) | |
559 | { | |
560 | temp << "..."; | |
561 | break; | |
562 | } | |
563 | ||
564 | current_cname = get_cname(current_host, false); | |
565 | if (current_cname.Host.empty()) | |
566 | break; | |
567 | else | |
568 | { | |
569 | current_host = current_cname.Host; | |
570 | temp << "-->" << current_host; | |
a176d17a | 571 | ++n_recursions; |
e638894d CH |
572 | } |
573 | } | |
574 | return temp.str(); | |
575 | } |