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