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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 | |
946356e1 | 25 | #include <fstream> |
96779587 | 26 | #include <logfunc.hpp> |
946356e1 | 27 | #include <filefunc.hxx> // I2n::file_exists |
e18c1337 | 28 | #include <boost/foreach.hpp> |
96779587 CH |
29 | #include <boost/bind.hpp> |
30 | #include <boost/date_time/posix_time/posix_time.hpp> | |
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 | { | |
48 | int SaveTimerSeconds = 60; | |
dbe986b9 | 49 | int MaxRetrievalRecursions = 10; |
96779587 CH |
50 | } |
51 | ||
23f51766 CH |
52 | Cname::Cname() |
53 | : Host() | |
54 | , Ttl() | |
55 | {} | |
56 | ||
57 | Cname::Cname(const std::string &host, const uint32_t ttl) | |
58 | : Host( host ) | |
59 | , Ttl( ttl ) | |
60 | {} | |
61 | ||
26b0f687 CH |
62 | Cname::Cname(const std::string &host, const TimeToLive &ttl) |
63 | : Host( host ) | |
64 | , Ttl( ttl ) | |
65 | {} | |
66 | ||
8d26221d CH |
67 | |
68 | const string DnsCache::DoNotUseCacheFile = "do not use cache file!"; | |
69 | ||
96779587 CH |
70 | DnsCache::DnsCache(const IoServiceItem &io_serv, |
71 | const std::string &cache_file) | |
ad83004d CH |
72 | : IpCache() |
73 | , CnameCache() | |
96779587 CH |
74 | , SaveTimer( *io_serv ) |
75 | , CacheFile( cache_file ) | |
76 | , HasChanged( false ) | |
77 | { | |
78 | // load cache from file | |
79 | load_from_cachefile(); | |
80 | ||
81 | // schedule next save | |
82 | (void) SaveTimer.expires_from_now( seconds( Config::SaveTimerSeconds ) ); | |
83 | SaveTimer.async_wait( bind( &DnsCache::schedule_save, this, | |
84 | boost::asio::placeholders::error ) ); | |
85 | } | |
86 | ||
87 | ||
88 | DnsCache::~DnsCache() | |
89 | { | |
26b0f687 | 90 | GlobalLogger.info() << "DnsCache: being destructed"; |
e91538f0 | 91 | |
96779587 CH |
92 | // save one last time without re-scheduling the next save |
93 | save_to_cachefile(); | |
94 | ||
95 | // cancel save timer | |
96 | SaveTimer.cancel(); | |
97 | } | |
98 | ||
99 | ||
100 | void DnsCache::schedule_save(const boost::system::error_code &error) | |
101 | { | |
102 | // just in case: ensure SaveTimer is cancelled | |
103 | SaveTimer.cancel(); // (will do nothing if already expired/cancelled) | |
104 | ||
105 | if ( error == boost::asio::error::operation_aborted ) // cancelled | |
106 | { | |
ad83004d | 107 | GlobalLogger.error() << "DnsCache: SaveTimer was cancelled " |
96779587 CH |
108 | << "--> no save and no re-schedule of saving!"; |
109 | return; | |
110 | } | |
111 | else if (error) | |
112 | { | |
ad83004d | 113 | GlobalLogger.error() << "DnsCache: Received error " << error |
96779587 CH |
114 | << " in schedule_save " |
115 | << "--> no save now but re-schedule saving"; | |
116 | } | |
117 | else | |
118 | save_to_cachefile(); | |
119 | ||
120 | // schedule next save | |
121 | (void) SaveTimer.expires_from_now( seconds( Config::SaveTimerSeconds ) ); | |
122 | SaveTimer.async_wait( bind( &DnsCache::schedule_save, this, | |
123 | boost::asio::placeholders::error ) ); | |
124 | } | |
125 | ||
126 | void DnsCache::save_to_cachefile() | |
127 | { | |
128 | if (!HasChanged) | |
ad83004d | 129 | GlobalLogger.info() << "DnsCache: skip saving because has not changed"; |
946356e1 | 130 | else if (CacheFile.empty()) |
946356e1 | 131 | GlobalLogger.warning() |
ad83004d | 132 | << "DnsCache: skip saving because file name empty!"; |
8d26221d | 133 | else if (CacheFile == DoNotUseCacheFile) |
26b0f687 CH |
134 | GlobalLogger.info() << "DnsCache: configured not to use cache file"; |
135 | else | |
946356e1 | 136 | { |
26b0f687 CH |
137 | try |
138 | { | |
139 | std::ofstream ofs( CacheFile.c_str() ); | |
140 | boost::archive::xml_oarchive oa(ofs); | |
141 | //oa << boost::serialization::make_nvp("IpCache", IpCache); | |
142 | //oa << boost::serialization::make_nvp("CnameCache", CnameCache); | |
143 | oa & BOOST_SERIALIZATION_NVP(IpCache); | |
144 | oa & BOOST_SERIALIZATION_NVP(CnameCache); | |
8d26221d CH |
145 | GlobalLogger.info() << "DnsCache: saved to cache file " |
146 | << CacheFile; | |
26b0f687 CH |
147 | |
148 | HasChanged = false; | |
149 | } | |
150 | catch (std::exception &exc) | |
151 | { | |
c1abff61 | 152 | GlobalLogger.warning() << "DnsCache: Saving failed: " << exc.what(); |
26b0f687 | 153 | } |
946356e1 | 154 | } |
96779587 CH |
155 | } |
156 | ||
96779587 CH |
157 | void DnsCache::load_from_cachefile() |
158 | { | |
946356e1 | 159 | if (CacheFile.empty()) |
946356e1 | 160 | GlobalLogger.warning() |
8d26221d CH |
161 | << "DnsCache: cannot load because cache file name is empty!"; |
162 | else if (CacheFile == DoNotUseCacheFile) | |
26b0f687 | 163 | GlobalLogger.info() << "DnsCache: configured not to use cache file"; |
946356e1 | 164 | else if ( !I2n::file_exists(CacheFile) ) |
ad83004d | 165 | GlobalLogger.warning() << "DnsCache: cannot load because cache file " |
946356e1 | 166 | << CacheFile << " does not exist!"; |
26b0f687 | 167 | else |
946356e1 | 168 | { |
26b0f687 CH |
169 | try |
170 | { | |
171 | std::ifstream ifs( CacheFile.c_str() ); | |
172 | boost::archive::xml_iarchive ia(ifs); | |
946356e1 | 173 | |
26b0f687 CH |
174 | ia & BOOST_SERIALIZATION_NVP(IpCache); |
175 | ia & BOOST_SERIALIZATION_NVP(CnameCache); | |
176 | GlobalLogger.info() << "DnsCache: loaded from file " << CacheFile; | |
177 | } | |
178 | catch (boost::archive::archive_exception &exc) | |
179 | { | |
8d26221d CH |
180 | GlobalLogger.warning() |
181 | << "DnsCache: archive exception loading from " << CacheFile | |
182 | << ": " << exc.what(); | |
26b0f687 CH |
183 | } |
184 | catch (std::exception &exc) | |
185 | { | |
186 | GlobalLogger.warning() << "DnsCache: exception while loading from " | |
187 | << CacheFile << ": " << exc.what(); | |
188 | } | |
946356e1 | 189 | } |
96779587 CH |
190 | } |
191 | ||
26b0f687 CH |
192 | |
193 | // warn if hostname is empty and remove trailing dot | |
194 | std::string DnsCache::key_for_hostname(const std::string &hostname) const | |
96779587 | 195 | { |
26b0f687 CH |
196 | if (hostname.empty()) |
197 | { | |
198 | GlobalLogger.warning() << "DnsCache: empty host!"; | |
199 | return ""; | |
200 | } | |
201 | ||
202 | // check whether last character is a dot | |
203 | if (hostname.rfind('.') == hostname.length()-1) | |
204 | return hostname.substr(0, hostname.length()-1); | |
205 | else | |
206 | return hostname; | |
96779587 CH |
207 | } |
208 | ||
209 | ||
ad83004d | 210 | void DnsCache::update(const std::string &hostname, |
26b0f687 | 211 | const HostAddressVec &new_ips) |
ad83004d | 212 | { |
26b0f687 CH |
213 | std::string key = key_for_hostname(hostname); |
214 | if ( !get_cname(hostname).Host.empty() ) | |
215 | { // ensure that there is never IP and CNAME for the same host | |
216 | GlobalLogger.warning() << "DnsCache: Saving IPs for " << key | |
217 | << " removes CNAME to " << get_cname(hostname).Host << "!"; | |
218 | update(hostname, Cname()); // overwrite with "empty" cname | |
219 | } | |
220 | GlobalLogger.debug() << "DnsCache: update IPs for " << key | |
221 | << " to " << new_ips.size() << "-list"; | |
222 | IpCache[key] = new_ips; | |
ad83004d CH |
223 | HasChanged = true; |
224 | } | |
225 | ||
226 | ||
dbe986b9 | 227 | void DnsCache::update(const std::string &hostname, |
26b0f687 | 228 | const Cname &cname) |
ad83004d | 229 | { |
26b0f687 CH |
230 | std::string key = key_for_hostname(hostname); |
231 | if ( !get_ips(hostname).empty() ) | |
232 | { // ensure that there is never IP and CNAME for the same host | |
233 | GlobalLogger.warning() << "DnsCache: Saving CNAME for " << key | |
234 | << " removes " << get_ips(hostname).size() << " IPs for same host!"; | |
235 | update(hostname, HostAddressVec()); // overwrite with empty IP list | |
ad83004d | 236 | } |
26b0f687 CH |
237 | |
238 | // remove possible trailing dot from cname | |
239 | Cname to_save = Cname(key_for_hostname(cname.Host), | |
240 | cname.Ttl); | |
241 | ||
242 | GlobalLogger.info() << "DnsCache: update CNAME for " << key | |
243 | << " to " << to_save.Host; | |
244 | CnameCache[key] = to_save; | |
245 | HasChanged = true; | |
ad83004d CH |
246 | } |
247 | ||
248 | ||
23f51766 CH |
249 | /** |
250 | * @returns empty list if no (up to date) ips for hostname in cache | |
251 | */ | |
dbe986b9 CH |
252 | HostAddressVec DnsCache::get_ips(const std::string &hostname, |
253 | const bool check_up_to_date) | |
96779587 | 254 | { |
26b0f687 CH |
255 | std::string key = key_for_hostname(hostname); |
256 | HostAddressVec result = IpCache[key]; | |
dbe986b9 CH |
257 | if (check_up_to_date) |
258 | { | |
259 | HostAddressVec result_up_to_date; | |
23f51766 CH |
260 | uint32_t threshold = static_cast<uint32_t>( |
261 | DnsMaster::get_instance()->get_resolved_ip_ttl_threshold() ); | |
26b0f687 | 262 | uint32_t updated_ttl; |
dbe986b9 CH |
263 | BOOST_FOREACH( const HostAddress &addr, result ) |
264 | { | |
26b0f687 CH |
265 | updated_ttl = addr.get_ttl().get_updated_value(); |
266 | if (updated_ttl > threshold) | |
dbe986b9 | 267 | result_up_to_date.push_back(addr); |
26b0f687 CH |
268 | else |
269 | GlobalLogger.debug() << "DnsCache: do not return " | |
270 | << addr.get_ip().to_string() << " since TTL " | |
271 | << updated_ttl << "s is out of date (thresh=" | |
272 | << threshold << "s)"; | |
dbe986b9 | 273 | } |
dbe986b9 CH |
274 | result = result_up_to_date; |
275 | } | |
26b0f687 CH |
276 | GlobalLogger.debug() << "DnsCache: request IPs for " << key |
277 | << " --> " << result.size() << "-list"; | |
278 | BOOST_FOREACH( const HostAddress &addr, result ) | |
279 | GlobalLogger.debug() << "DnsCache: " << addr.get_ip().to_string() | |
fd62d09f CH |
280 | << " (TTL " << addr.get_ttl().get_updated_value() |
281 | << "s)"; | |
dbe986b9 | 282 | return result; |
96779587 CH |
283 | } |
284 | ||
23f51766 CH |
285 | /** |
286 | * @returns empty cname if no (up to date cname) for hostname in cache | |
287 | */ | |
288 | Cname DnsCache::get_cname(const std::string &hostname, | |
289 | const bool check_up_to_date) | |
ad83004d | 290 | { |
26b0f687 CH |
291 | std::string key = key_for_hostname(hostname); |
292 | Cname result_obj = CnameCache[key]; | |
293 | GlobalLogger.debug() << "DnsCache: request CNAME for " << key | |
fd62d09f CH |
294 | << " --> \"" << result_obj.Host << "\" (TTL " |
295 | << result_obj.Ttl.get_updated_value() << "s)"; | |
23f51766 CH |
296 | if (result_obj.Host.empty()) |
297 | return result_obj; | |
298 | ||
299 | else if (check_up_to_date) | |
dbe986b9 | 300 | { |
26b0f687 CH |
301 | if ( result_obj.Ttl.get_updated_value() > static_cast<uint32_t>( |
302 | DnsMaster::get_instance()->get_resolved_ip_ttl_threshold()) ) | |
23f51766 | 303 | return result_obj; |
dbe986b9 CH |
304 | else |
305 | { | |
23f51766 CH |
306 | GlobalLogger.debug() << "DnsCache: CNAME is out of date"; |
307 | return Cname(); // same as if there was no cname for hostname | |
dbe986b9 CH |
308 | } |
309 | } | |
310 | else | |
23f51766 | 311 | return result_obj; |
ad83004d CH |
312 | } |
313 | ||
dbe986b9 CH |
314 | // underlying assumption in this function: for a hostname, the cache has either |
315 | // a list of IPs saved or a cname saved, but never both | |
316 | HostAddressVec DnsCache::get_ips_recursive(const std::string &hostname, | |
317 | const bool check_up_to_date) | |
e18c1337 CH |
318 | { |
319 | std::string current_host = hostname; | |
23f51766 | 320 | Cname current_cname; |
dbe986b9 CH |
321 | HostAddressVec result = get_ips(current_host); |
322 | int n_recursions = 0; | |
23f51766 | 323 | uint32_t min_cname_ttl = 0xffff; // largest possible unsigned 4-byte value |
e18c1337 CH |
324 | while ( result.empty() ) |
325 | { | |
23f51766 | 326 | current_cname = get_cname(current_host, check_up_to_date); |
8d26221d | 327 | if (current_cname.Host.empty()) |
e18c1337 | 328 | break; |
8d26221d CH |
329 | |
330 | current_host = key_for_hostname(current_cname.Host); | |
331 | if (++n_recursions >= Config::MaxRetrievalRecursions) | |
dbe986b9 CH |
332 | { |
333 | GlobalLogger.warning() << "DnsCache: reached recursion limit of " | |
334 | << n_recursions << " in recursive IP retrieval!"; | |
335 | break; | |
336 | } | |
e18c1337 | 337 | else |
23f51766 | 338 | { |
fd62d09f CH |
339 | min_cname_ttl = min(min_cname_ttl, |
340 | current_cname.Ttl.get_updated_value()); | |
dbe986b9 | 341 | result = get_ips(current_host, check_up_to_date); |
23f51766 CH |
342 | } |
343 | } | |
344 | ||
345 | GlobalLogger.debug() << "DnsCache: recursive IP retrieval resulted in " | |
346 | << result.size() << "-list after " << n_recursions | |
347 | << " recursions"; | |
348 | ||
349 | // adjust ttl to min of ttl and min_cname_ttl | |
350 | if (n_recursions > 0) | |
351 | { | |
352 | TimeToLive cname_ttl(min_cname_ttl); | |
353 | ||
354 | BOOST_FOREACH( HostAddress &addr, result ) | |
355 | { | |
fd62d09f | 356 | if (addr.get_ttl().get_updated_value() > min_cname_ttl) |
8d26221d CH |
357 | { |
358 | GlobalLogger.debug() << "DnsCache: using shorter CNAME TTL"; | |
23f51766 | 359 | addr.set_ttl(cname_ttl); |
8d26221d | 360 | } |
23f51766 | 361 | } |
e18c1337 | 362 | } |
23f51766 | 363 | |
e18c1337 CH |
364 | return result; |
365 | } | |
ad83004d | 366 | |
23f51766 | 367 | /** |
9d1b2726 CH |
368 | * from a list of CNAMEs find the first one that is out of date or empty |
369 | * | |
370 | * returns the hostname that is out of date or empty if all CNAMEs are | |
371 | * up-to-date | |
23f51766 CH |
372 | * |
373 | * required in ResolverBase::get_skipper | |
23f51766 CH |
374 | */ |
375 | std::string DnsCache::get_first_outdated_cname(const std::string &hostname, | |
376 | const uint32_t ttl_thresh) | |
377 | { | |
8d26221d | 378 | std::string first_outdated = hostname; |
23f51766 CH |
379 | Cname cname; |
380 | int n_recursions = 0; | |
381 | while (true) | |
382 | { | |
383 | if (++n_recursions >= Config::MaxRetrievalRecursions) | |
384 | { | |
385 | GlobalLogger.warning() << "DnsCache: reached recursion limit of " | |
386 | << n_recursions << " in search of outdated CNAMEs!"; | |
9d1b2726 CH |
387 | return first_outdated; // not really out of date but currently |
388 | } // our best guess | |
23f51766 | 389 | |
8d26221d CH |
390 | cname = get_cname(first_outdated); |
391 | if (cname.Host.empty()) | |
9d1b2726 CH |
392 | // reached end of cname list --> everything was up-to-date |
393 | return ""; | |
23f51766 CH |
394 | else if (cname.Ttl.get_updated_value() > ttl_thresh) |
395 | // cname is up to date --> continue looking | |
8d26221d | 396 | first_outdated = cname.Host; |
23f51766 | 397 | else |
9d1b2726 CH |
398 | // cname is out of date --> return its target |
399 | return cname.Host; | |
23f51766 | 400 | } |
9d1b2726 CH |
401 | // reach this point only if cname chain does not end with an IP |
402 | // --> all are up-to-date | |
403 | return ""; | |
23f51766 | 404 | } |