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36ad976b 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 | |
4e7b6ff9 CH |
21 | |
22 | with code copied from boost::net::dns::resolve.hpp | |
23 | by Andreas Haberstroh (andreas at ibusy dot com) | |
24 | from https://github.com/softwareace/Boost.DNS | |
36ad976b CH |
25 | */ |
26 | ||
c5b4902d CH |
27 | #include "dns/dnsresolver.h" |
28 | ||
29 | #include <stdint.h> | |
e91538f0 | 30 | #include <sstream> |
36ad976b | 31 | |
4e7b6ff9 CH |
32 | #include <boost/foreach.hpp> |
33 | #include <boost/bind.hpp> | |
34 | #include <boost/function.hpp> | |
35 | #include <boost/net/dns.hpp> | |
36 | #include <boost/date_time/posix_time/posix_time.hpp> | |
ad83004d CH |
37 | #include <boost/uuid/uuid.hpp> |
38 | #include <boost/uuid/uuid_io.hpp> | |
4e7b6ff9 | 39 | |
36ad976b | 40 | #include <logfunc.hpp> |
4e7b6ff9 | 41 | |
36ad976b | 42 | using I2n::Logger::GlobalLogger; |
4e7b6ff9 CH |
43 | using boost::posix_time::seconds; |
44 | using boost::posix_time::minutes; | |
36ad976b CH |
45 | |
46 | namespace Config | |
47 | { | |
dbe986b9 | 48 | const int ResolveTimeoutSeconds = 3; |
96779587 CH |
49 | const int PauseBeforeRetrySeconds = 10; |
50 | const int StaleDataLongtermMinutes = 15; | |
36ad976b | 51 | const int DNS_PORT = 53; |
36ad976b CH |
52 | } |
53 | ||
4e7b6ff9 CH |
54 | DnsResolver::DnsResolver(IoServiceItem &io_serv, |
55 | const std::string &hostname, | |
923626c0 | 56 | const DnsIpProtocol &protocol, |
96779587 | 57 | const DnsCacheItem cache, |
96779587 | 58 | const boost::asio::ip::address &name_server) |
4e7b6ff9 | 59 | : ResolverBase( io_serv, hostname, cache ) |
e91538f0 CH |
60 | , Socket( *io_serv, ip::udp::endpoint(ip::udp::v4(), 0)) |
61 | // just connect to anything, will specify sender/receiver later | |
4e7b6ff9 | 62 | , ReceiveBuffer() |
ad83004d | 63 | , RequestBuffer() |
923626c0 | 64 | , Protocol( protocol ) |
4e7b6ff9 | 65 | , NameServer( name_server, Config::DNS_PORT ) |
36ad976b CH |
66 | , ResolveTimeoutTimer( *io_serv ) |
67 | , PauseBeforeRetryTimer( *io_serv ) | |
68 | , StaleDataLongtermTimer( *io_serv ) | |
4e7b6ff9 | 69 | , NextIpIndex( 0 ) |
36ad976b CH |
70 | , RetryCount( 0 ) |
71 | , IsResolving( false ) | |
e91538f0 | 72 | , LogPrefix( "DnsResolver" ) |
ad83004d CH |
73 | , RandomIdGenerator() |
74 | , RequestId( 0 ) | |
e18c1337 | 75 | , OperationCancelled( false ) |
e91538f0 CH |
76 | { |
77 | std::stringstream temp; | |
78 | temp << "Dns(" << ResolverBase::Hostname << "): "; | |
79 | LogPrefix = temp.str(); | |
ad83004d | 80 | |
e91538f0 | 81 | } |
96779587 | 82 | |
c5b4902d CH |
83 | DnsResolver::~DnsResolver() |
84 | { | |
85 | boost::system::error_code error; | |
e18c1337 CH |
86 | //Socket.shutdown(boost::asio::ip::udp::socket::shutdown_both, error); |
87 | //if ( error ) | |
88 | // GlobalLogger.warning() << LogPrefix << "Received error " << error | |
89 | // << " when shutting down socket for DNS"; | |
90 | // in IcmpPinger always gave an error system:9 (EBADF: Bad file descriptor) | |
91 | // Here gives error system:107 ENOTCONN: Transport endpoint is not connected | |
c5b4902d CH |
92 | |
93 | Socket.close(error); | |
94 | if ( error ) | |
e91538f0 | 95 | GlobalLogger.warning() << LogPrefix << "Received error " << error |
c5b4902d CH |
96 | << " when closing socket for DNS"; |
97 | } | |
98 | ||
99 | ||
96779587 CH |
100 | |
101 | //============================================================================== | |
102 | // ASYNC RESOLVE | |
103 | //============================================================================== | |
36ad976b CH |
104 | |
105 | /** | |
c5b4902d | 106 | * copied here code from boost::net::dns::resolve.hpp, since want async |
36ad976b | 107 | * operation and that is used only internally, there |
36ad976b | 108 | */ |
4e7b6ff9 | 109 | void DnsResolver::do_resolve() |
36ad976b | 110 | { |
36ad976b | 111 | // check if resolving already |
4e7b6ff9 | 112 | if (IsResolving) |
36ad976b | 113 | { |
e91538f0 | 114 | GlobalLogger.info() << LogPrefix |
4e7b6ff9 | 115 | << "Call to do_resolve ignored since resolving already"; |
36ad976b CH |
116 | return; |
117 | } | |
ad83004d | 118 | IsResolving = true; |
e18c1337 | 119 | OperationCancelled = false; |
36ad976b | 120 | |
e18c1337 CH |
121 | GlobalLogger.info() << LogPrefix << "start resolving for IPs of type " |
122 | << to_string(Protocol) << " using name server " << NameServer; | |
e91538f0 | 123 | |
36ad976b CH |
124 | // just to be sure: cancel timers |
125 | ResolveTimeoutTimer.cancel(); | |
126 | PauseBeforeRetryTimer.cancel(); | |
127 | StaleDataLongtermTimer.cancel(); | |
128 | ||
129 | // create DNS request | |
e18c1337 | 130 | boost::net::dns::message dns_message( ResolverBase::Hostname, Protocol ); |
23f51766 | 131 | dns_message.recursive(true); |
4e7b6ff9 CH |
132 | dns_message.action(boost::net::dns::message::query); |
133 | dns_message.opcode(boost::net::dns::message::squery); | |
ad83004d CH |
134 | |
135 | // create random ID for message | |
136 | boost::uuids::uuid message_id = RandomIdGenerator(); | |
137 | memcpy( &RequestId, message_id.data, sizeof(RequestId) ); | |
138 | dns_message.id( RequestId ); | |
139 | GlobalLogger.debug() << LogPrefix << "Request has ID " | |
140 | << std::showbase << std::hex << dns_message.id(); | |
36ad976b CH |
141 | |
142 | // setup receipt of reply | |
143 | Socket.async_receive_from( | |
144 | boost::asio::buffer(ReceiveBuffer.get_array()), | |
145 | NameServer, | |
146 | boost::bind( &DnsResolver::handle_dns_result, this, | |
147 | boost::asio::placeholders::error, | |
148 | boost::asio::placeholders::bytes_transferred) | |
4e7b6ff9 | 149 | ); |
36ad976b CH |
150 | |
151 | // schedule timeout | |
4e7b6ff9 CH |
152 | (void) ResolveTimeoutTimer.expires_from_now( |
153 | seconds(Config::ResolveTimeoutSeconds)); | |
154 | ResolveTimeoutTimer.async_wait( boost::bind( | |
155 | &DnsResolver::handle_resolve_timeout, | |
156 | this, boost::asio::placeholders::error) ); | |
36ad976b CH |
157 | |
158 | // send dns request | |
ad83004d | 159 | dns_message.encode(RequestBuffer); |
e91538f0 CH |
160 | size_t bytes_sent; |
161 | try | |
162 | { | |
163 | bytes_sent = Socket.send_to( | |
ad83004d | 164 | boost::asio::buffer(RequestBuffer.get_array()), |
e91538f0 CH |
165 | NameServer ); |
166 | } | |
167 | catch (boost::system::system_error &err) | |
168 | { | |
169 | GlobalLogger.warning() << LogPrefix | |
170 | << "Sending of DNS request message failed: " | |
171 | << err.what(); | |
e18c1337 | 172 | schedule_retry(); |
e91538f0 CH |
173 | return; |
174 | } | |
175 | ||
176 | if ( bytes_sent == 0 ) | |
177 | { | |
178 | GlobalLogger.warning() << LogPrefix << "Empty DNS request sent!"; | |
e18c1337 | 179 | schedule_retry(); |
e91538f0 CH |
180 | return; |
181 | } | |
36ad976b CH |
182 | } |
183 | ||
184 | ||
4e7b6ff9 | 185 | void DnsResolver::handle_dns_result(const boost::system::error_code &error, |
ad83004d | 186 | const std::size_t bytes_transferred) |
36ad976b | 187 | { |
e18c1337 | 188 | if (error) |
36ad976b | 189 | { |
e91538f0 | 190 | GlobalLogger.info() << LogPrefix << "DNS resolve resulted in error " |
e18c1337 CH |
191 | << error << " --> try again after a little while"; |
192 | schedule_retry(); | |
193 | return; | |
194 | } | |
195 | else if ( OperationCancelled ) | |
196 | { // async_resolve was cancelled --> callbacks already called | |
197 | GlobalLogger.info() << LogPrefix | |
198 | << "Ignoring DNS results since we were cancelled"; | |
36ad976b CH |
199 | return; |
200 | } | |
201 | ||
ad83004d CH |
202 | GlobalLogger.debug() << LogPrefix << "Handling DNS result (" |
203 | << bytes_transferred << " bytes transferred)"; | |
204 | ||
36ad976b CH |
205 | // next 3(+1) lines copied from boost/net/dns/resolver.hpp: |
206 | // clamp the recvBuffer with the number of bytes transferred or decode buffr | |
207 | ReceiveBuffer.length(bytes_transferred); | |
4e7b6ff9 | 208 | boost::net::dns::message result_message; |
36ad976b CH |
209 | result_message.decode( ReceiveBuffer ); |
210 | ||
ad83004d CH |
211 | // check ID |
212 | if (RequestId != result_message.id()) | |
e18c1337 | 213 | GlobalLogger.warning() << LogPrefix << "Received answer for request ID " |
ad83004d CH |
214 | << std::showbase << std::hex << result_message.id() |
215 | << " but expected ID " << RequestId; | |
216 | else | |
217 | GlobalLogger.debug() << LogPrefix << "Result has correct ID " | |
218 | << std::showbase << std::hex << RequestId; | |
e18c1337 | 219 | RequestId = 0; |
ad83004d CH |
220 | |
221 | // loop over answers, remembering ips and cnames | |
4e7b6ff9 CH |
222 | // work with a regular pointer to list of answers since result_message is |
223 | // owner of data and that exists until end of function | |
224 | // Items in answers list are shared_ptr to resource_base_t | |
e18c1337 | 225 | std::vector<host_addr_pair> result_ips; |
dbe986b9 CH |
226 | std::vector<src_cname_pair> result_cnames; |
227 | std::vector<string_pair> result_name_servers; | |
36ad976b | 228 | |
c1abff61 | 229 | GlobalLogger.debug() << LogPrefix <<"Checking ANSWERS section of dns reply"; |
e18c1337 | 230 | gather_results(result_message.answers(), &result_ips, &result_cnames, |
dbe986b9 | 231 | &result_name_servers); |
e18c1337 CH |
232 | // results should have the logical order |
233 | // Hostname [ --> cname1 --> cname2 --> ... --> cnameN ] [ --> ips ] | |
ad83004d | 234 | |
e18c1337 | 235 | // remember cname list (if there were any) |
dbe986b9 | 236 | BOOST_FOREACH( const src_cname_pair &host_and_cname, result_cnames ) |
e18c1337 | 237 | ResolverBase::update_cache(host_and_cname.first, host_and_cname.second); |
ad83004d | 238 | |
e18c1337 CH |
239 | if ( !result_ips.empty() ) |
240 | handle_ips( result_ips ); | |
ad83004d | 241 | else if ( !result_cnames.empty() ) |
e18c1337 CH |
242 | // no IPs but at least one cname --> find the "last" cname and |
243 | // re-start resolving with that | |
244 | handle_cname(result_cnames); | |
ad83004d | 245 | else |
23f51766 CH |
246 | { // no answers --> cannot proceed |
247 | GlobalLogger.warning() << LogPrefix << "No IP nor CNAME received! " | |
248 | << "--> schedule retry"; | |
249 | schedule_retry(); | |
ad83004d | 250 | } |
ad83004d CH |
251 | } |
252 | ||
23f51766 CH |
253 | /** |
254 | * gather IPs, CNAMEs and name servers from list of resource records; | |
255 | * | |
256 | * can be run on anwers(), autorities() and additional() sections of dns reply | |
257 | * messages | |
258 | * | |
259 | * @param rr_list: input list of resource records | |
260 | * @param result_ips: output vector of ips | |
261 | * @param result_cnames: output vector of cnames | |
262 | * @param result_name_servers: output vector of name servers | |
263 | */ | |
264 | void DnsResolver::gather_results(const boost::net::dns::rr_list_t *rr_list, | |
e18c1337 | 265 | std::vector<host_addr_pair> *result_ips, |
dbe986b9 CH |
266 | std::vector<src_cname_pair> *result_cnames, |
267 | std::vector<string_pair> *result_name_servers) | |
ad83004d CH |
268 | const |
269 | { | |
4e7b6ff9 | 270 | using boost::net::dns::resource_base_t; |
dbe986b9 | 271 | boost::posix_time::ptime now =boost::posix_time::second_clock::local_time(); |
23f51766 | 272 | BOOST_FOREACH( boost::shared_ptr<resource_base_t> rr_item, *rr_list ) |
36ad976b | 273 | { |
4e7b6ff9 | 274 | boost::net::dns::type_t rr_type = rr_item->rtype(); |
ad83004d CH |
275 | uint32_t ttl = rr_item->ttl(); |
276 | std::string domain = rr_item->domain(); | |
dbe986b9 CH |
277 | std::string expiry = |
278 | boost::posix_time::to_simple_string(now + seconds(ttl)); | |
36ad976b CH |
279 | |
280 | if (rr_type == boost::net::dns::type_a) | |
281 | { // 'A' resource records carry IPv4 addresses | |
923626c0 CH |
282 | if (Protocol == DNS_IPv6) |
283 | { | |
e91538f0 CH |
284 | GlobalLogger.info() << LogPrefix << "Ignoring IPv4 address " |
285 | << "because resolver was configured to only use IPv6."; | |
923626c0 CH |
286 | continue; |
287 | } | |
4e7b6ff9 CH |
288 | boost::asio::ip::address_v4 ip = |
289 | ( dynamic_cast<boost::net::dns::a_resource *> (rr_item.get()) ) | |
290 | ->address(); | |
e18c1337 | 291 | result_ips->push_back(host_addr_pair(domain, HostAddress(ip, ttl))); |
dbe986b9 CH |
292 | GlobalLogger.debug() << LogPrefix << domain << ": IPv4 " << ip |
293 | << " with TTL " << ttl << "s (until " | |
294 | << expiry << ")"; | |
36ad976b CH |
295 | } |
296 | else if (rr_type == boost::net::dns::type_a6) | |
297 | { // 'AAAA' resource records carry IPv6 addresses | |
923626c0 CH |
298 | if (Protocol == DNS_IPv4) |
299 | { | |
e91538f0 CH |
300 | GlobalLogger.info() << LogPrefix << "Ignoring IPv6 address " |
301 | << "because resolver was configured to only use IPv4."; | |
923626c0 CH |
302 | continue; |
303 | } | |
4e7b6ff9 CH |
304 | boost::asio::ip::address_v6 ip = |
305 | ( dynamic_cast<boost::net::dns::a6_resource *> (rr_item.get()) ) | |
306 | ->address(); | |
e18c1337 | 307 | result_ips->push_back(host_addr_pair(domain, HostAddress(ip, ttl))); |
dbe986b9 CH |
308 | GlobalLogger.debug() << LogPrefix << domain << ": IPv6 " << ip |
309 | << " with TTL " << ttl << "s (until " | |
310 | << expiry << ")"; | |
36ad976b CH |
311 | } |
312 | else if (rr_type == boost::net::dns::type_cname) | |
313 | { // 'CNAME' resource records that carry aliases | |
4e7b6ff9 CH |
314 | std::string cname = |
315 | (dynamic_cast<boost::net::dns::cname_resource *>(rr_item.get())) | |
316 | ->canonicalname(); | |
dbe986b9 CH |
317 | result_cnames->push_back( src_cname_pair(domain, |
318 | Cname(cname, ttl)) ); | |
319 | GlobalLogger.debug() << LogPrefix << domain << ": CNAME to " | |
320 | << cname << " with TTL " << ttl << "s (until " | |
321 | << expiry << ")"; | |
36ad976b CH |
322 | } |
323 | else if (rr_type == boost::net::dns::type_ns) | |
dbe986b9 CH |
324 | { // NS (name_server) resource records |
325 | std::string name_server = | |
ad83004d CH |
326 | (dynamic_cast<boost::net::dns::ns_resource *>(rr_item.get())) |
327 | ->nameserver(); | |
dbe986b9 CH |
328 | result_name_servers->push_back( string_pair(domain, name_server) ); |
329 | GlobalLogger.debug() << LogPrefix << "NameServer " << name_server | |
330 | << " for " << domain << " with TTL " << ttl | |
331 | << "s (until " << expiry << ")"; | |
ad83004d | 332 | } |
36ad976b | 333 | else if (rr_type == boost::net::dns::type_soa) |
e91538f0 | 334 | GlobalLogger.debug() << LogPrefix << "SOA resource"; |
36ad976b | 335 | else if (rr_type == boost::net::dns::type_ptr) |
e91538f0 | 336 | GlobalLogger.debug() << LogPrefix << "ptr resource"; |
36ad976b | 337 | else if (rr_type == boost::net::dns::type_hinfo) |
e91538f0 | 338 | GlobalLogger.debug() << LogPrefix << "hinfo resource"; |
36ad976b | 339 | else if (rr_type == boost::net::dns::type_mx) |
e91538f0 | 340 | GlobalLogger.debug() << LogPrefix << "mx resource"; |
36ad976b | 341 | else if (rr_type == boost::net::dns::type_txt) |
e91538f0 | 342 | GlobalLogger.debug() << LogPrefix << "txt resource"; |
36ad976b | 343 | else if (rr_type == boost::net::dns::type_srv) |
e91538f0 | 344 | GlobalLogger.debug() << LogPrefix << "srv resource"; |
36ad976b | 345 | else if (rr_type == boost::net::dns::type_axfr) |
e91538f0 | 346 | GlobalLogger.debug() << LogPrefix << "axfr resource"; |
36ad976b | 347 | else |
ad83004d CH |
348 | GlobalLogger.debug() << LogPrefix << "unknown resource type: " |
349 | << std::showbase << std::hex | |
350 | << static_cast<unsigned>(rr_item->rtype()); | |
36ad976b | 351 | } |
36ad976b CH |
352 | } |
353 | ||
354 | ||
36ad976b CH |
355 | void DnsResolver::handle_unavailable() |
356 | { | |
357 | // schedule new attempt in quite a while | |
4e7b6ff9 CH |
358 | StaleDataLongtermTimer.expires_from_now( |
359 | minutes(Config::StaleDataLongtermMinutes)); | |
36ad976b | 360 | StaleDataLongtermTimer.async_wait( |
4e7b6ff9 CH |
361 | boost::bind( &DnsResolver::wait_timer_timeout_handler, |
362 | this, boost::asio::placeholders::error | |
36ad976b CH |
363 | ) |
364 | ); | |
365 | ||
366 | // for now, admit failure | |
367 | bool was_success = false; | |
96779587 | 368 | finalize_resolve(was_success); |
36ad976b CH |
369 | } |
370 | ||
e18c1337 CH |
371 | |
372 | void DnsResolver::handle_ips(const std::vector<host_addr_pair> &result_ips) | |
36ad976b | 373 | { |
e18c1337 CH |
374 | // received at least one IP which could be for the queried host name |
375 | // or the cname at the "end" of the cname list; | |
376 | // but all IPs should be for the same | |
377 | HostAddressVec addr_list; | |
378 | std::string only_host_for_ips = result_ips[0].first; | |
379 | BOOST_FOREACH( const host_addr_pair &host_and_addr, result_ips) | |
380 | { | |
381 | if ( host_and_addr.first != only_host_for_ips ) | |
382 | GlobalLogger.warning() << LogPrefix | |
383 | << "Received IPs for different hosts " << only_host_for_ips | |
384 | << " and " << host_and_addr.first << " in one DNS result! " | |
385 | << "--> ignore second"; | |
386 | else | |
387 | { | |
388 | GlobalLogger.notice() << LogPrefix << "Found IP " | |
389 | << host_and_addr.second.get_ip() << " with TTL " | |
390 | << host_and_addr.second.get_ttl().get_value() << "s"; | |
391 | addr_list.push_back(host_and_addr.second); | |
392 | } | |
393 | } | |
394 | ResolverBase::update_cache( only_host_for_ips, addr_list ); | |
36ad976b | 395 | |
e18c1337 CH |
396 | // clean up |
397 | bool was_success = true; | |
398 | finalize_resolve(was_success); | |
399 | } | |
400 | ||
401 | ||
dbe986b9 | 402 | void DnsResolver::handle_cname(const std::vector<src_cname_pair> &result_cnames) |
e18c1337 CH |
403 | { |
404 | // find the "last" cname in the list | |
405 | // Hostname --> cname1 --> cname2 --> ... --> cnameN | |
406 | // We assume here that this list might not be in order but that all cnames | |
dbe986b9 CH |
407 | // form a single list (form one connected list and not several isolated) |
408 | ||
e18c1337 CH |
409 | std::string last_cname = ""; |
410 | bool could_be_last; | |
dbe986b9 | 411 | BOOST_REVERSE_FOREACH( const src_cname_pair &host_and_cname, result_cnames ) |
e18c1337 CH |
412 | { |
413 | could_be_last = true; | |
dbe986b9 | 414 | BOOST_REVERSE_FOREACH( const src_cname_pair &other, result_cnames ) |
e18c1337 | 415 | { |
23f51766 | 416 | if (other.first == host_and_cname.second.Host) |
e18c1337 CH |
417 | { // found cname for current cname |
418 | could_be_last = false; | |
419 | break; | |
420 | } | |
421 | } | |
422 | if (could_be_last) | |
423 | { | |
23f51766 | 424 | last_cname = host_and_cname.second.Host; |
e18c1337 CH |
425 | break; |
426 | } | |
427 | } | |
428 | ||
429 | if (last_cname.empty()) | |
430 | { | |
431 | GlobalLogger.error() << LogPrefix | |
432 | << "Could not identify \"last\" CNAME to handle -- " | |
433 | << "maybe we encountered a CNAME loop? Anyway, cannot proceed!"; | |
434 | GlobalLogger.info() << LogPrefix << "Result CNAMEs were:"; | |
dbe986b9 | 435 | BOOST_FOREACH( const src_cname_pair &host_and_cname, result_cnames ) |
e18c1337 | 436 | GlobalLogger.info() << LogPrefix << host_and_cname.first << " --> " |
23f51766 | 437 | << host_and_cname.second.Host; |
e18c1337 CH |
438 | handle_unavailable(); |
439 | } | |
440 | else | |
441 | { // check cache for IP for this cname | |
442 | bool check_up_to_date = true; | |
443 | HostAddressVec cached_data = Cache->get_ips_recursive(last_cname, | |
444 | check_up_to_date); | |
445 | if ( !cached_data.empty() ) | |
446 | { | |
447 | bool was_success = true; | |
23f51766 CH |
448 | int cname_count = 1; // define cache access as only 1 |
449 | finalize_resolve(was_success, cname_count); | |
e18c1337 CH |
450 | } |
451 | else | |
452 | { // get resolver for canonical name | |
e18c1337 CH |
453 | ResolverItem resolver = DnsMaster::get_instance() |
454 | ->get_resolver_for(last_cname, Protocol); | |
455 | callback_type callback = boost::bind( | |
456 | &DnsResolver::cname_resolve_callback, | |
457 | this, _1, _2 ); | |
458 | resolver->async_resolve( callback ); | |
459 | ||
460 | // treat a CNAME as a partial result: not enough to run callbacks | |
461 | // from finalize_resolve, but enough to stop timers and reset | |
462 | // RetryCount --> name resolution can take longer | |
463 | stop_trying(); | |
464 | } | |
465 | } | |
36ad976b CH |
466 | } |
467 | ||
468 | ||
e18c1337 | 469 | void DnsResolver::cname_resolve_callback(const bool was_success, |
23f51766 | 470 | const int cname_count) |
36ad976b | 471 | { |
e18c1337 CH |
472 | if ( OperationCancelled ) |
473 | { // async_resolve was cancelled --> callbacks already called | |
474 | GlobalLogger.info() << LogPrefix | |
475 | << "Ignoring CNAME results since we were cancelled"; | |
476 | return; | |
477 | } | |
478 | else if (was_success) | |
479 | GlobalLogger.debug() << LogPrefix << "CNAME resolution succeeded"; | |
96779587 | 480 | else |
e18c1337 CH |
481 | GlobalLogger.info() << LogPrefix << "CNAME resolution failed"; |
482 | // no use to schedule retry in this case since cname resolver must have | |
23f51766 CH |
483 | // failed several times and we can only re-start the same procedure with |
484 | // the same information | |
96779587 | 485 | |
e18c1337 | 486 | // cname counts like one more recursion step ... |
23f51766 | 487 | finalize_resolve(was_success, cname_count+1); |
dbe986b9 CH |
488 | } |
489 | ||
490 | ||
96779587 | 491 | void DnsResolver::finalize_resolve(const bool was_success, |
23f51766 | 492 | const int cname_count) |
96779587 | 493 | { |
e18c1337 CH |
494 | // some consistency checks; failure might indicate a situation I had not |
495 | // anticipated during programming but might not be harmfull yet | |
496 | if ( !IsResolving ) | |
497 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
498 | << "not resolving any more!"; | |
499 | if ( OperationCancelled ) | |
500 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
501 | << " was cancelled!"; | |
502 | if ( ResolverBase::CallbackList.empty() ) | |
503 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
504 | << "no callbacks!"; | |
505 | if ( RequestId != 0 ) | |
506 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
507 | << "waiting for DNS reply!"; | |
508 | ||
96779587 | 509 | // stop timers |
e18c1337 | 510 | stop_trying(); |
96779587 CH |
511 | |
512 | // schedule callbacks, clearing callback list | |
23f51766 | 513 | ResolverBase::schedule_callbacks(was_success, cname_count); |
96779587 CH |
514 | |
515 | // finalize | |
e18c1337 | 516 | GlobalLogger.notice() << LogPrefix << "finalized resolve" |
96779587 | 517 | << " with success = " << was_success |
23f51766 | 518 | << " and cname_count = " << cname_count; |
96779587 CH |
519 | IsResolving = false; |
520 | } | |
521 | ||
e18c1337 | 522 | |
96779587 CH |
523 | void DnsResolver::stop_trying() |
524 | { | |
525 | // cancel timers | |
e91538f0 | 526 | GlobalLogger.debug() << LogPrefix << "Cancelling timers"; |
96779587 CH |
527 | ResolveTimeoutTimer.cancel(); |
528 | PauseBeforeRetryTimer.cancel(); | |
529 | StaleDataLongtermTimer.cancel(); | |
530 | ||
531 | // clean up | |
532 | RetryCount = 0; | |
533 | } | |
534 | ||
e18c1337 CH |
535 | |
536 | bool DnsResolver::is_resolving() | |
537 | { | |
538 | return IsResolving; | |
539 | } | |
540 | ||
541 | ||
dbe986b9 CH |
542 | /** |
543 | * cancel a earlier call to async_resolve | |
544 | * | |
545 | * callbacks will be called with was_success=false; all internal operations | |
546 | * will be cancelled and internal callbacks (timers, dns results) have no | |
547 | * effect any more | |
548 | */ | |
e18c1337 CH |
549 | void DnsResolver::cancel_resolve() |
550 | { | |
551 | if ( !IsResolving ) | |
552 | { | |
553 | GlobalLogger.info() << LogPrefix | |
554 | << "Cancel called on non-resolving resolver -- ignore"; | |
555 | return; | |
556 | } | |
557 | else if (OperationCancelled) | |
558 | { | |
559 | GlobalLogger.info() << LogPrefix | |
560 | << "Cancel called on cancelled resolver -- ignore"; | |
561 | return; | |
562 | } | |
563 | ||
e18c1337 | 564 | // set before finalize_resolve so can check in finalize_resolve that ID is |
dbe986b9 | 565 | // always 0; ID is not used any more since handle_dns_result stops if |
e18c1337 CH |
566 | // OperationCancelled is true |
567 | RequestId = 0; | |
568 | ||
569 | bool was_success = false; | |
23f51766 CH |
570 | int cname_count = 1; |
571 | finalize_resolve(was_success, cname_count); | |
e18c1337 CH |
572 | |
573 | // set after finalize_resolve, so can check in finalize_resolve that | |
dbe986b9 | 574 | // OperationCancelled is never true |
e18c1337 CH |
575 | OperationCancelled = true; |
576 | ||
577 | } | |
578 | ||
579 | ||
4e7b6ff9 | 580 | void DnsResolver::handle_resolve_timeout(const boost::system::error_code &error) |
96779587 CH |
581 | { |
582 | if ( error == boost::asio::error::operation_aborted ) // cancelled | |
583 | { | |
8d26221d CH |
584 | GlobalLogger.info() << LogPrefix |
585 | << "Resolve timeout timer was cancelled!"; | |
96779587 CH |
586 | return; |
587 | } | |
588 | else if (error) | |
589 | { | |
e91538f0 CH |
590 | GlobalLogger.warning() << LogPrefix |
591 | << "resolve timeout handler received error " | |
dbe986b9 CH |
592 | << error << " --> retry"; |
593 | schedule_retry(); | |
96779587 | 594 | } |
e18c1337 CH |
595 | else if ( OperationCancelled ) |
596 | { // async_resolve was cancelled --> callbacks already called | |
597 | GlobalLogger.info() << LogPrefix | |
dbe986b9 | 598 | << "Ignoring DNS timeout since we were cancelled"; |
e18c1337 CH |
599 | return; |
600 | } | |
601 | else | |
602 | { | |
603 | GlobalLogger.notice() << LogPrefix << "DNS resolving timed out"; | |
e18c1337 CH |
604 | schedule_retry(); |
605 | } | |
606 | } | |
607 | ||
96779587 | 608 | |
e18c1337 CH |
609 | void DnsResolver::schedule_retry() |
610 | { | |
23f51766 | 611 | // cancel timers |
e18c1337 CH |
612 | ResolveTimeoutTimer.cancel(); |
613 | PauseBeforeRetryTimer.cancel(); | |
36ad976b | 614 | |
96779587 CH |
615 | // increment timer |
616 | ++RetryCount; | |
617 | ||
923626c0 CH |
618 | if ( RetryCount > DnsMaster::get_instance() |
619 | ->get_max_address_resolution_attempts() ) | |
e18c1337 CH |
620 | { // too many re-tries |
621 | GlobalLogger.info() << LogPrefix << "Not scheduling a retry since " | |
622 | << "RetryCount " << RetryCount << " too high"; | |
623 | handle_unavailable(); // will call stop_trying i.e. reset RetryCount | |
96779587 CH |
624 | } |
625 | else | |
626 | { // schedule retry | |
e18c1337 CH |
627 | GlobalLogger.info() << LogPrefix << "Scheduling a retry (RetryCount=" |
628 | << RetryCount << ")"; | |
96779587 | 629 | PauseBeforeRetryTimer.expires_from_now( |
4e7b6ff9 | 630 | seconds(Config::PauseBeforeRetrySeconds)); |
96779587 | 631 | PauseBeforeRetryTimer.async_wait( |
4e7b6ff9 CH |
632 | boost::bind( &DnsResolver::wait_timer_timeout_handler, |
633 | this, boost::asio::placeholders::error) ); | |
96779587 CH |
634 | } |
635 | } | |
636 | ||
637 | void DnsResolver::wait_timer_timeout_handler( | |
638 | const boost::system::error_code &error) | |
639 | { | |
640 | if ( error == boost::asio::error::operation_aborted ) // cancelled | |
e18c1337 CH |
641 | { // assume that our code cancelled this timer, so callbacks will be |
642 | // taken care of! | |
8d26221d CH |
643 | GlobalLogger.info() << LogPrefix |
644 | << "Resolve wait timer was cancelled! "; | |
e18c1337 | 645 | } |
96779587 | 646 | else if (error) |
e18c1337 CH |
647 | { // not sure what to do here, but callers waiting forever for a callback |
648 | // is probably the worst thing to happen, so call finalize_resolve | |
e91538f0 | 649 | GlobalLogger.warning() << LogPrefix |
e18c1337 CH |
650 | << "resolve wait handler received error " |
651 | << error << "! Try to finalize resolve"; | |
652 | bool was_success = false; | |
653 | finalize_resolve(was_success); | |
654 | } | |
655 | else if ( OperationCancelled ) | |
656 | { // async_resolve was cancelled --> callbacks already called | |
657 | GlobalLogger.info() << LogPrefix | |
658 | << "Ignoring waiting timeout since we were cancelled"; | |
659 | return; | |
660 | } | |
96779587 CH |
661 | else |
662 | { | |
e91538f0 | 663 | GlobalLogger.info() << LogPrefix << "Done waiting --> re-try resolve"; |
4e7b6ff9 | 664 | do_resolve(); |
96779587 | 665 | } |
36ad976b CH |
666 | } |
667 | ||
668 | ||
96779587 CH |
669 | //============================================================================== |
670 | // RETRIEVAL | |
671 | //============================================================================== | |
672 | ||
26b0f687 | 673 | HostAddress DnsResolver::get_next_ip(bool check_up_to_date) |
36ad976b CH |
674 | { |
675 | // get cached data | |
26b0f687 CH |
676 | // (do not use arg check_up_to_date here in order to give NextIpIndex |
677 | // a chance to stay above number of outdate IPs) | |
e18c1337 | 678 | HostAddressVec cached_data = ResolverBase::get_cached_ips_recursively(); |
96779587 CH |
679 | |
680 | // if no results cached, return default-constructed HostAddress (0.0.0.0) | |
26b0f687 | 681 | HostAddress return_candidate; |
96779587 | 682 | if ( cached_data.empty() ) |
4e7b6ff9 | 683 | { |
26b0f687 CH |
684 | GlobalLogger.debug() << LogPrefix << "Get next IP: nothing cached"; |
685 | return return_candidate; | |
4e7b6ff9 | 686 | } |
36ad976b | 687 | |
26b0f687 CH |
688 | int n_iter = 0; |
689 | std::size_t n_ips = cached_data.size(); | |
690 | uint32_t ttl_thresh = static_cast<uint32_t>( DnsMaster::get_instance() | |
691 | ->get_resolved_ip_ttl_threshold() ); | |
36ad976b | 692 | |
26b0f687 CH |
693 | GlobalLogger.info() << LogPrefix << "Get next IP from cached result of " |
694 | << n_ips << " IPs; first index to consider is " << NextIpIndex | |
695 | << "; TTL thresh = " << ttl_thresh << " is used: " << check_up_to_date; | |
696 | ||
697 | // loop until we have found a cached result (that is up to date) | |
698 | // or until we have tried all cached IPs | |
699 | while (true) | |
700 | { | |
701 | // check index since cache size may have changed since last call | |
702 | if (NextIpIndex >= n_ips) | |
703 | NextIpIndex = 0; | |
704 | else if ( n_iter >= n_ips) | |
705 | return HostAddress(); // have checked all candidates | |
706 | else | |
707 | { // there are candidates left to consider | |
708 | return_candidate = cached_data[NextIpIndex++]; | |
709 | if (!check_up_to_date) | |
710 | return return_candidate; | |
711 | else if (cached_data[NextIpIndex].get_ttl().get_updated_value() | |
712 | > ttl_thresh) | |
713 | return cached_data[++NextIpIndex]; | |
714 | else | |
715 | ++n_iter; | |
716 | } | |
717 | } | |
36ad976b CH |
718 | } |
719 | ||
923626c0 CH |
720 | bool DnsResolver::have_up_to_date_ip() |
721 | { | |
26b0f687 | 722 | return get_resolved_ip_count() > 0; |
923626c0 CH |
723 | } |
724 | ||
725 | int DnsResolver::get_resolved_ip_count() | |
726 | { | |
8d26221d CH |
727 | // run with empty hostname (--> uses internal var Hostname) |
728 | // and check_up_to_date = true | |
26b0f687 | 729 | return ResolverBase::get_cached_ips_recursively("", true).size(); |
923626c0 CH |
730 | } |
731 |