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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 | 43 | using boost::posix_time::seconds; |
36ad976b CH |
44 | |
45 | namespace Config | |
46 | { | |
fd62d09f CH |
47 | const int ResolveTimeoutSeconds = 2; |
48 | const int PauseBeforeRetrySeconds = 1; | |
49 | const int StaleDataLongtermSeconds = 5*60; | |
36ad976b | 50 | const int DNS_PORT = 53; |
36ad976b CH |
51 | } |
52 | ||
4e7b6ff9 CH |
53 | DnsResolver::DnsResolver(IoServiceItem &io_serv, |
54 | const std::string &hostname, | |
923626c0 | 55 | const DnsIpProtocol &protocol, |
96779587 | 56 | const DnsCacheItem cache, |
96779587 | 57 | const boost::asio::ip::address &name_server) |
8f00b3df | 58 | : ResolverBase( io_serv, hostname, protocol, cache ) |
e91538f0 CH |
59 | , Socket( *io_serv, ip::udp::endpoint(ip::udp::v4(), 0)) |
60 | // just connect to anything, will specify sender/receiver later | |
4e7b6ff9 | 61 | , ReceiveBuffer() |
ad83004d | 62 | , RequestBuffer() |
4e7b6ff9 | 63 | , NameServer( name_server, Config::DNS_PORT ) |
36ad976b CH |
64 | , ResolveTimeoutTimer( *io_serv ) |
65 | , PauseBeforeRetryTimer( *io_serv ) | |
66 | , StaleDataLongtermTimer( *io_serv ) | |
4e7b6ff9 | 67 | , NextIpIndex( 0 ) |
36ad976b CH |
68 | , RetryCount( 0 ) |
69 | , IsResolving( false ) | |
e91538f0 | 70 | , LogPrefix( "DnsResolver" ) |
ad83004d CH |
71 | , RandomIdGenerator() |
72 | , RequestId( 0 ) | |
e18c1337 | 73 | , OperationCancelled( false ) |
fd62d09f | 74 | , LongtermTimerIsActive( false ) |
e91538f0 CH |
75 | { |
76 | std::stringstream temp; | |
77 | temp << "Dns(" << ResolverBase::Hostname << "): "; | |
78 | LogPrefix = temp.str(); | |
ad83004d | 79 | |
e91538f0 | 80 | } |
96779587 | 81 | |
c5b4902d CH |
82 | DnsResolver::~DnsResolver() |
83 | { | |
84 | boost::system::error_code error; | |
e18c1337 CH |
85 | //Socket.shutdown(boost::asio::ip::udp::socket::shutdown_both, error); |
86 | //if ( error ) | |
49b82a1d | 87 | // GlobalLogger.info() << LogPrefix << "Received error " << error |
e18c1337 CH |
88 | // << " when shutting down socket for DNS"; |
89 | // in IcmpPinger always gave an error system:9 (EBADF: Bad file descriptor) | |
90 | // Here gives error system:107 ENOTCONN: Transport endpoint is not connected | |
c5b4902d CH |
91 | |
92 | Socket.close(error); | |
93 | if ( error ) | |
49b82a1d CH |
94 | GlobalLogger.info() << LogPrefix << "Received error " << error |
95 | << " when closing socket for DNS"; | |
c5b4902d CH |
96 | } |
97 | ||
98 | ||
96779587 CH |
99 | |
100 | //============================================================================== | |
101 | // ASYNC RESOLVE | |
102 | //============================================================================== | |
36ad976b CH |
103 | |
104 | /** | |
c5b4902d | 105 | * copied here code from boost::net::dns::resolve.hpp, since want async |
36ad976b | 106 | * operation and that is used only internally, there |
36ad976b | 107 | */ |
cd71d095 | 108 | void DnsResolver::do_resolve(const int recursion_count) |
36ad976b | 109 | { |
36ad976b | 110 | // check if resolving already |
4e7b6ff9 | 111 | if (IsResolving) |
36ad976b | 112 | { |
e91538f0 | 113 | GlobalLogger.info() << LogPrefix |
4e7b6ff9 | 114 | << "Call to do_resolve ignored since resolving already"; |
36ad976b CH |
115 | return; |
116 | } | |
ad83004d | 117 | IsResolving = true; |
e18c1337 | 118 | OperationCancelled = false; |
36ad976b | 119 | |
e18c1337 CH |
120 | GlobalLogger.info() << LogPrefix << "start resolving for IPs of type " |
121 | << to_string(Protocol) << " using name server " << NameServer; | |
e91538f0 | 122 | |
36ad976b CH |
123 | // just to be sure: cancel timers |
124 | ResolveTimeoutTimer.cancel(); | |
125 | PauseBeforeRetryTimer.cancel(); | |
126 | StaleDataLongtermTimer.cancel(); | |
fd62d09f | 127 | LongtermTimerIsActive = false; |
36ad976b CH |
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 " | |
cd71d095 | 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, | |
cd71d095 | 147 | recursion_count, |
36ad976b CH |
148 | boost::asio::placeholders::error, |
149 | boost::asio::placeholders::bytes_transferred) | |
4e7b6ff9 | 150 | ); |
36ad976b CH |
151 | |
152 | // schedule timeout | |
4e7b6ff9 CH |
153 | (void) ResolveTimeoutTimer.expires_from_now( |
154 | seconds(Config::ResolveTimeoutSeconds)); | |
155 | ResolveTimeoutTimer.async_wait( boost::bind( | |
156 | &DnsResolver::handle_resolve_timeout, | |
cd71d095 CH |
157 | this, recursion_count, |
158 | boost::asio::placeholders::error) ); | |
36ad976b CH |
159 | |
160 | // send dns request | |
ad83004d | 161 | dns_message.encode(RequestBuffer); |
e91538f0 CH |
162 | size_t bytes_sent; |
163 | try | |
164 | { | |
165 | bytes_sent = Socket.send_to( | |
ad83004d | 166 | boost::asio::buffer(RequestBuffer.get_array()), |
e91538f0 CH |
167 | NameServer ); |
168 | } | |
169 | catch (boost::system::system_error &err) | |
170 | { | |
49b82a1d | 171 | GlobalLogger.info() << LogPrefix |
e91538f0 CH |
172 | << "Sending of DNS request message failed: " |
173 | << err.what(); | |
cd71d095 | 174 | schedule_retry(recursion_count); |
e91538f0 CH |
175 | return; |
176 | } | |
177 | ||
178 | if ( bytes_sent == 0 ) | |
179 | { | |
49b82a1d | 180 | GlobalLogger.info() << LogPrefix << "Empty DNS request sent!"; |
cd71d095 | 181 | schedule_retry(recursion_count); |
e91538f0 CH |
182 | return; |
183 | } | |
36ad976b CH |
184 | } |
185 | ||
186 | ||
cd71d095 CH |
187 | void DnsResolver::handle_dns_result(const int recursion_count, |
188 | const boost::system::error_code &error, | |
ad83004d | 189 | const std::size_t bytes_transferred) |
36ad976b | 190 | { |
e18c1337 | 191 | if (error) |
36ad976b | 192 | { |
e91538f0 | 193 | GlobalLogger.info() << LogPrefix << "DNS resolve resulted in error " |
fd62d09f | 194 | << error << " --> request retry"; |
cd71d095 | 195 | schedule_retry(recursion_count); |
e18c1337 CH |
196 | return; |
197 | } | |
198 | else if ( OperationCancelled ) | |
199 | { // async_resolve was cancelled --> callbacks already called | |
200 | GlobalLogger.info() << LogPrefix | |
201 | << "Ignoring DNS results since we were cancelled"; | |
36ad976b CH |
202 | return; |
203 | } | |
204 | ||
ad83004d CH |
205 | GlobalLogger.debug() << LogPrefix << "Handling DNS result (" |
206 | << bytes_transferred << " bytes transferred)"; | |
207 | ||
36ad976b CH |
208 | // next 3(+1) lines copied from boost/net/dns/resolver.hpp: |
209 | // clamp the recvBuffer with the number of bytes transferred or decode buffr | |
210 | ReceiveBuffer.length(bytes_transferred); | |
4e7b6ff9 | 211 | boost::net::dns::message result_message; |
36ad976b CH |
212 | result_message.decode( ReceiveBuffer ); |
213 | ||
ad83004d | 214 | // check ID |
3f489614 CH |
215 | if (RequestId == 0) |
216 | { // system DNS or firewall might have longer timeout than me | |
217 | // --> might receive replies for old requests whose time-out has expired | |
218 | // --> have already called callbacks etc, so nothing to do with result | |
219 | // TODO: did receive probably same data several times --> reset buffer? | |
220 | GlobalLogger.info() << LogPrefix << "Ignoring reply to old DNS request " | |
221 | << "(reply has ID " << std::showbase << std::hex | |
222 | << result_message.id() << " or buffer not reset)"; | |
223 | return; | |
224 | } | |
225 | else if (RequestId != result_message.id()) | |
226 | { | |
49b82a1d | 227 | GlobalLogger.info() << LogPrefix << "Received answer for request ID " |
ad83004d | 228 | << std::showbase << std::hex << result_message.id() |
3f489614 CH |
229 | << " but expected ID " << RequestId << " --> ignore and retry"; |
230 | schedule_retry(recursion_count); | |
231 | return; | |
232 | } | |
ad83004d CH |
233 | else |
234 | GlobalLogger.debug() << LogPrefix << "Result has correct ID " | |
235 | << std::showbase << std::hex << RequestId; | |
e18c1337 | 236 | RequestId = 0; |
ad83004d CH |
237 | |
238 | // loop over answers, remembering ips and cnames | |
4e7b6ff9 CH |
239 | // work with a regular pointer to list of answers since result_message is |
240 | // owner of data and that exists until end of function | |
241 | // Items in answers list are shared_ptr to resource_base_t | |
e18c1337 | 242 | std::vector<host_addr_pair> result_ips; |
dbe986b9 CH |
243 | std::vector<src_cname_pair> result_cnames; |
244 | std::vector<string_pair> result_name_servers; | |
36ad976b | 245 | |
c1abff61 | 246 | GlobalLogger.debug() << LogPrefix <<"Checking ANSWERS section of dns reply"; |
e18c1337 | 247 | gather_results(result_message.answers(), &result_ips, &result_cnames, |
dbe986b9 | 248 | &result_name_servers); |
ad83004d | 249 | |
e18c1337 | 250 | // remember cname list (if there were any) |
cd71d095 CH |
251 | // results should have the logical order |
252 | // Hostname [ --> cname1 --> cname2 --> ... --> cnameN ] [ --> ips ]; | |
253 | // otherwise just have unneccessary cnames in cache | |
dbe986b9 | 254 | BOOST_FOREACH( const src_cname_pair &host_and_cname, result_cnames ) |
e18c1337 | 255 | ResolverBase::update_cache(host_and_cname.first, host_and_cname.second); |
ad83004d | 256 | |
e18c1337 | 257 | if ( !result_ips.empty() ) |
cd71d095 | 258 | handle_ips( recursion_count, result_ips ); |
ad83004d | 259 | else if ( !result_cnames.empty() ) |
e18c1337 CH |
260 | // no IPs but at least one cname --> find the "last" cname and |
261 | // re-start resolving with that | |
cd71d095 | 262 | handle_cname(recursion_count, result_cnames); |
ad83004d | 263 | else |
23f51766 | 264 | { // no answers --> cannot proceed |
49b82a1d | 265 | GlobalLogger.info() << LogPrefix << "No IP nor CNAME received! " |
fd62d09f | 266 | << "--> request retry"; |
cd71d095 | 267 | schedule_retry(recursion_count); |
ad83004d | 268 | } |
ad83004d CH |
269 | } |
270 | ||
23f51766 CH |
271 | /** |
272 | * gather IPs, CNAMEs and name servers from list of resource records; | |
273 | * | |
274 | * can be run on anwers(), autorities() and additional() sections of dns reply | |
275 | * messages | |
cd71d095 | 276 | * |
23f51766 CH |
277 | * @param rr_list: input list of resource records |
278 | * @param result_ips: output vector of ips | |
279 | * @param result_cnames: output vector of cnames | |
280 | * @param result_name_servers: output vector of name servers | |
281 | */ | |
282 | void DnsResolver::gather_results(const boost::net::dns::rr_list_t *rr_list, | |
e18c1337 | 283 | std::vector<host_addr_pair> *result_ips, |
dbe986b9 CH |
284 | std::vector<src_cname_pair> *result_cnames, |
285 | std::vector<string_pair> *result_name_servers) | |
ad83004d CH |
286 | const |
287 | { | |
4e7b6ff9 | 288 | using boost::net::dns::resource_base_t; |
dbe986b9 | 289 | boost::posix_time::ptime now =boost::posix_time::second_clock::local_time(); |
23f51766 | 290 | BOOST_FOREACH( boost::shared_ptr<resource_base_t> rr_item, *rr_list ) |
36ad976b | 291 | { |
4e7b6ff9 | 292 | boost::net::dns::type_t rr_type = rr_item->rtype(); |
ad83004d CH |
293 | uint32_t ttl = rr_item->ttl(); |
294 | std::string domain = rr_item->domain(); | |
dbe986b9 CH |
295 | std::string expiry = |
296 | boost::posix_time::to_simple_string(now + seconds(ttl)); | |
36ad976b CH |
297 | |
298 | if (rr_type == boost::net::dns::type_a) | |
299 | { // 'A' resource records carry IPv4 addresses | |
923626c0 CH |
300 | if (Protocol == DNS_IPv6) |
301 | { | |
e91538f0 CH |
302 | GlobalLogger.info() << LogPrefix << "Ignoring IPv4 address " |
303 | << "because resolver was configured to only use IPv6."; | |
923626c0 CH |
304 | continue; |
305 | } | |
4e7b6ff9 CH |
306 | boost::asio::ip::address_v4 ip = |
307 | ( dynamic_cast<boost::net::dns::a_resource *> (rr_item.get()) ) | |
308 | ->address(); | |
e18c1337 | 309 | result_ips->push_back(host_addr_pair(domain, HostAddress(ip, ttl))); |
dbe986b9 CH |
310 | GlobalLogger.debug() << LogPrefix << domain << ": IPv4 " << ip |
311 | << " with TTL " << ttl << "s (until " | |
312 | << expiry << ")"; | |
36ad976b CH |
313 | } |
314 | else if (rr_type == boost::net::dns::type_a6) | |
315 | { // 'AAAA' resource records carry IPv6 addresses | |
923626c0 CH |
316 | if (Protocol == DNS_IPv4) |
317 | { | |
e91538f0 CH |
318 | GlobalLogger.info() << LogPrefix << "Ignoring IPv6 address " |
319 | << "because resolver was configured to only use IPv4."; | |
923626c0 CH |
320 | continue; |
321 | } | |
4e7b6ff9 CH |
322 | boost::asio::ip::address_v6 ip = |
323 | ( dynamic_cast<boost::net::dns::a6_resource *> (rr_item.get()) ) | |
324 | ->address(); | |
e18c1337 | 325 | result_ips->push_back(host_addr_pair(domain, HostAddress(ip, ttl))); |
dbe986b9 CH |
326 | GlobalLogger.debug() << LogPrefix << domain << ": IPv6 " << ip |
327 | << " with TTL " << ttl << "s (until " | |
328 | << expiry << ")"; | |
36ad976b CH |
329 | } |
330 | else if (rr_type == boost::net::dns::type_cname) | |
331 | { // 'CNAME' resource records that carry aliases | |
4e7b6ff9 CH |
332 | std::string cname = |
333 | (dynamic_cast<boost::net::dns::cname_resource *>(rr_item.get())) | |
334 | ->canonicalname(); | |
dbe986b9 CH |
335 | result_cnames->push_back( src_cname_pair(domain, |
336 | Cname(cname, ttl)) ); | |
337 | GlobalLogger.debug() << LogPrefix << domain << ": CNAME to " | |
338 | << cname << " with TTL " << ttl << "s (until " | |
339 | << expiry << ")"; | |
36ad976b CH |
340 | } |
341 | else if (rr_type == boost::net::dns::type_ns) | |
dbe986b9 CH |
342 | { // NS (name_server) resource records |
343 | std::string name_server = | |
ad83004d CH |
344 | (dynamic_cast<boost::net::dns::ns_resource *>(rr_item.get())) |
345 | ->nameserver(); | |
dbe986b9 CH |
346 | result_name_servers->push_back( string_pair(domain, name_server) ); |
347 | GlobalLogger.debug() << LogPrefix << "NameServer " << name_server | |
348 | << " for " << domain << " with TTL " << ttl | |
349 | << "s (until " << expiry << ")"; | |
ad83004d | 350 | } |
36ad976b | 351 | else if (rr_type == boost::net::dns::type_soa) |
e91538f0 | 352 | GlobalLogger.debug() << LogPrefix << "SOA resource"; |
36ad976b | 353 | else if (rr_type == boost::net::dns::type_ptr) |
e91538f0 | 354 | GlobalLogger.debug() << LogPrefix << "ptr resource"; |
36ad976b | 355 | else if (rr_type == boost::net::dns::type_hinfo) |
e91538f0 | 356 | GlobalLogger.debug() << LogPrefix << "hinfo resource"; |
36ad976b | 357 | else if (rr_type == boost::net::dns::type_mx) |
e91538f0 | 358 | GlobalLogger.debug() << LogPrefix << "mx resource"; |
36ad976b | 359 | else if (rr_type == boost::net::dns::type_txt) |
e91538f0 | 360 | GlobalLogger.debug() << LogPrefix << "txt resource"; |
36ad976b | 361 | else if (rr_type == boost::net::dns::type_srv) |
e91538f0 | 362 | GlobalLogger.debug() << LogPrefix << "srv resource"; |
36ad976b | 363 | else if (rr_type == boost::net::dns::type_axfr) |
e91538f0 | 364 | GlobalLogger.debug() << LogPrefix << "axfr resource"; |
36ad976b | 365 | else |
ad83004d CH |
366 | GlobalLogger.debug() << LogPrefix << "unknown resource type: " |
367 | << std::showbase << std::hex | |
368 | << static_cast<unsigned>(rr_item->rtype()); | |
36ad976b | 369 | } |
36ad976b CH |
370 | } |
371 | ||
372 | ||
cd71d095 | 373 | void DnsResolver::handle_unavailable(const int recursion_count) |
36ad976b CH |
374 | { |
375 | // schedule new attempt in quite a while | |
4e7b6ff9 | 376 | StaleDataLongtermTimer.expires_from_now( |
fd62d09f | 377 | seconds(Config::StaleDataLongtermSeconds)); |
36ad976b | 378 | StaleDataLongtermTimer.async_wait( |
cd71d095 CH |
379 | boost::bind( &DnsResolver::wait_timer_timeout_handler, this, |
380 | recursion_count, | |
381 | boost::asio::placeholders::error | |
36ad976b CH |
382 | ) |
383 | ); | |
fd62d09f | 384 | LongtermTimerIsActive = true; |
36ad976b CH |
385 | |
386 | // for now, admit failure | |
3f489614 | 387 | RequestId = 0; // do not accept answers from old requests |
36ad976b | 388 | bool was_success = false; |
cd71d095 | 389 | finalize_resolve(was_success, recursion_count); |
36ad976b CH |
390 | } |
391 | ||
e18c1337 | 392 | |
cd71d095 CH |
393 | void DnsResolver::handle_ips(const int recursion_count, |
394 | const std::vector<host_addr_pair> &result_ips) | |
36ad976b | 395 | { |
cd71d095 | 396 | // received at least one IP which could be for the queried host name |
e18c1337 CH |
397 | // or the cname at the "end" of the cname list; |
398 | // but all IPs should be for the same | |
399 | HostAddressVec addr_list; | |
400 | std::string only_host_for_ips = result_ips[0].first; | |
401 | BOOST_FOREACH( const host_addr_pair &host_and_addr, result_ips) | |
402 | { | |
403 | if ( host_and_addr.first != only_host_for_ips ) | |
49b82a1d | 404 | GlobalLogger.info() << LogPrefix |
e18c1337 CH |
405 | << "Received IPs for different hosts " << only_host_for_ips |
406 | << " and " << host_and_addr.first << " in one DNS result! " | |
407 | << "--> ignore second"; | |
408 | else | |
409 | { | |
49b82a1d | 410 | GlobalLogger.info() << LogPrefix << "Found IP " |
e18c1337 CH |
411 | << host_and_addr.second.get_ip() << " with TTL " |
412 | << host_and_addr.second.get_ttl().get_value() << "s"; | |
413 | addr_list.push_back(host_and_addr.second); | |
414 | } | |
415 | } | |
416 | ResolverBase::update_cache( only_host_for_ips, addr_list ); | |
36ad976b | 417 | |
e18c1337 CH |
418 | // clean up |
419 | bool was_success = true; | |
cd71d095 | 420 | finalize_resolve(was_success, recursion_count); |
e18c1337 CH |
421 | } |
422 | ||
423 | ||
cd71d095 CH |
424 | void DnsResolver::handle_cname(const int recursion_count, |
425 | const std::vector<src_cname_pair> &result_cnames) | |
e18c1337 CH |
426 | { |
427 | // find the "last" cname in the list | |
428 | // Hostname --> cname1 --> cname2 --> ... --> cnameN | |
429 | // We assume here that this list might not be in order but that all cnames | |
cd71d095 CH |
430 | // form a single list (form one connected list and not several independent |
431 | // lists) | |
dbe986b9 | 432 | |
e18c1337 CH |
433 | std::string last_cname = ""; |
434 | bool could_be_last; | |
dbe986b9 | 435 | BOOST_REVERSE_FOREACH( const src_cname_pair &host_and_cname, result_cnames ) |
e18c1337 CH |
436 | { |
437 | could_be_last = true; | |
dbe986b9 | 438 | BOOST_REVERSE_FOREACH( const src_cname_pair &other, result_cnames ) |
e18c1337 | 439 | { |
23f51766 | 440 | if (other.first == host_and_cname.second.Host) |
e18c1337 CH |
441 | { // found cname for current cname |
442 | could_be_last = false; | |
443 | break; | |
444 | } | |
445 | } | |
446 | if (could_be_last) | |
447 | { | |
23f51766 | 448 | last_cname = host_and_cname.second.Host; |
e18c1337 CH |
449 | break; |
450 | } | |
451 | } | |
452 | ||
453 | if (last_cname.empty()) | |
454 | { | |
49b82a1d | 455 | GlobalLogger.info() << LogPrefix |
e18c1337 CH |
456 | << "Could not identify \"last\" CNAME to handle -- " |
457 | << "maybe we encountered a CNAME loop? Anyway, cannot proceed!"; | |
458 | GlobalLogger.info() << LogPrefix << "Result CNAMEs were:"; | |
dbe986b9 | 459 | BOOST_FOREACH( const src_cname_pair &host_and_cname, result_cnames ) |
e18c1337 | 460 | GlobalLogger.info() << LogPrefix << host_and_cname.first << " --> " |
23f51766 | 461 | << host_and_cname.second.Host; |
cd71d095 | 462 | handle_unavailable(recursion_count); |
e18c1337 CH |
463 | } |
464 | else | |
465 | { // check cache for IP for this cname | |
466 | bool check_up_to_date = true; | |
8f00b3df | 467 | HostAddressVec cached_data = get_cached_ips_recursively(last_cname, |
e18c1337 CH |
468 | check_up_to_date); |
469 | if ( !cached_data.empty() ) | |
470 | { | |
471 | bool was_success = true; | |
cd71d095 | 472 | finalize_resolve(was_success, recursion_count+1); |
e18c1337 CH |
473 | } |
474 | else | |
475 | { // get resolver for canonical name | |
e18c1337 CH |
476 | ResolverItem resolver = DnsMaster::get_instance() |
477 | ->get_resolver_for(last_cname, Protocol); | |
478 | callback_type callback = boost::bind( | |
479 | &DnsResolver::cname_resolve_callback, | |
480 | this, _1, _2 ); | |
cd71d095 | 481 | resolver->async_resolve( callback, recursion_count+1 ); |
e18c1337 CH |
482 | |
483 | // treat a CNAME as a partial result: not enough to run callbacks | |
484 | // from finalize_resolve, but enough to stop timers and reset | |
485 | // RetryCount --> name resolution can take longer | |
72be9e7d | 486 | stop_trying(true); |
e18c1337 CH |
487 | } |
488 | } | |
36ad976b CH |
489 | } |
490 | ||
491 | ||
cd71d095 CH |
492 | /** |
493 | * the recursion_count here is really the one from the recursion, not the one | |
494 | * forwarded from async_resolve! | |
495 | */ | |
e18c1337 | 496 | void DnsResolver::cname_resolve_callback(const bool was_success, |
cd71d095 | 497 | const int recursion_count) |
36ad976b | 498 | { |
e18c1337 CH |
499 | if ( OperationCancelled ) |
500 | { // async_resolve was cancelled --> callbacks already called | |
501 | GlobalLogger.info() << LogPrefix | |
502 | << "Ignoring CNAME results since we were cancelled"; | |
503 | return; | |
504 | } | |
505 | else if (was_success) | |
72be9e7d | 506 | { |
cd71d095 CH |
507 | GlobalLogger.debug() << LogPrefix << "CNAME resolution succeeded after " |
508 | << recursion_count << " recursions"; | |
509 | finalize_resolve(was_success, recursion_count); | |
72be9e7d | 510 | } |
96779587 | 511 | else |
72be9e7d | 512 | { |
cd71d095 CH |
513 | GlobalLogger.info() << LogPrefix << "CNAME resolution failed after " |
514 | << recursion_count << " recursions"; | |
e18c1337 | 515 | // no use to schedule retry in this case since cname resolver must have |
23f51766 | 516 | // failed several times and we can only re-start the same procedure with |
72be9e7d | 517 | // the same information. But can re-try later |
cd71d095 | 518 | handle_unavailable(recursion_count); |
72be9e7d | 519 | } |
dbe986b9 CH |
520 | } |
521 | ||
522 | ||
cd71d095 CH |
523 | /** |
524 | * @brief always called at end of resolving process | |
525 | * | |
526 | * runs callbacks, resets timers and checks state consistency; only thing that | |
527 | * is "left alive" is the long-term timer that might cause a re-start of | |
528 | * resolution after a while | |
529 | * | |
530 | * @param was_success: indicates whether resolution was successfull | |
531 | * @param recursion_count number of recursions or (if not successfull) negative | |
532 | * value indicating who called this function | |
533 | */ | |
96779587 | 534 | void DnsResolver::finalize_resolve(const bool was_success, |
cd71d095 | 535 | const int recursion_count) |
96779587 | 536 | { |
e18c1337 CH |
537 | // some consistency checks; failure might indicate a situation I had not |
538 | // anticipated during programming but might not be harmfull yet | |
539 | if ( !IsResolving ) | |
540 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
541 | << "not resolving any more!"; | |
542 | if ( OperationCancelled ) | |
543 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
544 | << " was cancelled!"; | |
545 | if ( ResolverBase::CallbackList.empty() ) | |
546 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
547 | << "no callbacks!"; | |
548 | if ( RequestId != 0 ) | |
549 | GlobalLogger.warning() << LogPrefix << "Consistency check failed: " | |
550 | << "waiting for DNS reply!"; | |
551 | ||
96779587 | 552 | // stop timers |
72be9e7d | 553 | stop_trying(was_success); |
96779587 CH |
554 | |
555 | // schedule callbacks, clearing callback list | |
cd71d095 | 556 | ResolverBase::schedule_callbacks(was_success, recursion_count); |
96779587 CH |
557 | |
558 | // finalize | |
49b82a1d | 559 | GlobalLogger.info() << LogPrefix << "finalized resolve" |
96779587 | 560 | << " with success = " << was_success |
cd71d095 | 561 | << " and recursion_count = " << recursion_count; |
96779587 CH |
562 | IsResolving = false; |
563 | } | |
564 | ||
e18c1337 | 565 | |
72be9e7d CH |
566 | /** |
567 | * arg was_success determines if stop trying forever or just for the moment | |
568 | * --> determines if we cancel StaleDataLongtermTimer or not | |
569 | */ | |
570 | void DnsResolver::stop_trying(bool was_success) | |
96779587 CH |
571 | { |
572 | // cancel timers | |
e91538f0 | 573 | GlobalLogger.debug() << LogPrefix << "Cancelling timers"; |
96779587 CH |
574 | ResolveTimeoutTimer.cancel(); |
575 | PauseBeforeRetryTimer.cancel(); | |
72be9e7d CH |
576 | |
577 | if (was_success) | |
578 | { | |
579 | StaleDataLongtermTimer.cancel(); | |
fd62d09f | 580 | LongtermTimerIsActive = false; |
72be9e7d | 581 | } |
96779587 CH |
582 | |
583 | // clean up | |
584 | RetryCount = 0; | |
585 | } | |
586 | ||
e18c1337 | 587 | |
72be9e7d CH |
588 | /** |
589 | * return true if resolver is currently resolving | |
590 | * | |
591 | * Is true from call to async_resolve until callbacks | |
592 | * --> returns true if waiting for result or (short-term) retry | |
593 | * | |
cd71d095 | 594 | * However, does NOT tell you if the (long-term) stale timeout is active! |
72be9e7d CH |
595 | * That timer has no effect on result, need to check is_waiting_to_resolve |
596 | * for that | |
597 | */ | |
598 | bool DnsResolver::is_resolving() const | |
e18c1337 CH |
599 | { |
600 | return IsResolving; | |
601 | } | |
602 | ||
603 | ||
dbe986b9 | 604 | /** |
72be9e7d | 605 | * returns true if either is_resolving or the long-term timer is active |
cd71d095 | 606 | * |
72be9e7d CH |
607 | * is_resolving returns true if the short-term retry timer is active |
608 | */ | |
609 | bool DnsResolver::is_waiting_to_resolve() const | |
610 | { | |
fd62d09f | 611 | return IsResolving || LongtermTimerIsActive; |
72be9e7d CH |
612 | } |
613 | ||
614 | ||
615 | /** | |
dbe986b9 CH |
616 | * cancel a earlier call to async_resolve |
617 | * | |
618 | * callbacks will be called with was_success=false; all internal operations | |
619 | * will be cancelled and internal callbacks (timers, dns results) have no | |
72be9e7d | 620 | * effect any more; cancels also the long-term stale-data timer |
dbe986b9 | 621 | */ |
e18c1337 CH |
622 | void DnsResolver::cancel_resolve() |
623 | { | |
fd62d09f | 624 | if ( !IsResolving && !LongtermTimerIsActive) |
e18c1337 | 625 | { |
fd62d09f CH |
626 | GlobalLogger.info() << LogPrefix << "Cancel called on non-resolving, " |
627 | << "non-waiting resolver -- ignore"; | |
e18c1337 CH |
628 | return; |
629 | } | |
630 | else if (OperationCancelled) | |
631 | { | |
632 | GlobalLogger.info() << LogPrefix | |
633 | << "Cancel called on cancelled resolver -- ignore"; | |
634 | return; | |
635 | } | |
fd62d09f | 636 | GlobalLogger.info() << LogPrefix << "Cancel resolver"; |
e18c1337 | 637 | |
e18c1337 | 638 | // set before finalize_resolve so can check in finalize_resolve that ID is |
dbe986b9 | 639 | // always 0; ID is not used any more since handle_dns_result stops if |
e18c1337 CH |
640 | // OperationCancelled is true |
641 | RequestId = 0; | |
642 | ||
fd62d09f CH |
643 | if ( IsResolving ) |
644 | { | |
645 | bool was_success = false; | |
cd71d095 CH |
646 | int recursion_count = -1; |
647 | finalize_resolve(was_success, recursion_count); | |
fd62d09f | 648 | } |
e18c1337 | 649 | |
72be9e7d CH |
650 | // also cancel the long-term timer |
651 | StaleDataLongtermTimer.cancel(); | |
fd62d09f | 652 | LongtermTimerIsActive = false; |
72be9e7d | 653 | |
cd71d095 | 654 | // set after finalize_resolve, so can check in finalize_resolve that |
dbe986b9 | 655 | // OperationCancelled is never true |
e18c1337 CH |
656 | OperationCancelled = true; |
657 | ||
658 | } | |
659 | ||
660 | ||
cd71d095 CH |
661 | void DnsResolver::handle_resolve_timeout(const int recursion_count, |
662 | const boost::system::error_code &error) | |
96779587 CH |
663 | { |
664 | if ( error == boost::asio::error::operation_aborted ) // cancelled | |
665 | { | |
fd62d09f CH |
666 | GlobalLogger.debug() << LogPrefix |
667 | << "Resolve timeout timer was cancelled!"; | |
96779587 CH |
668 | return; |
669 | } | |
670 | else if (error) | |
671 | { | |
49b82a1d | 672 | GlobalLogger.info() << LogPrefix |
e91538f0 | 673 | << "resolve timeout handler received error " |
fd62d09f | 674 | << error << " --> request retry"; |
cd71d095 | 675 | schedule_retry(recursion_count); |
96779587 | 676 | } |
e18c1337 CH |
677 | else if ( OperationCancelled ) |
678 | { // async_resolve was cancelled --> callbacks already called | |
679 | GlobalLogger.info() << LogPrefix | |
dbe986b9 | 680 | << "Ignoring DNS timeout since we were cancelled"; |
e18c1337 CH |
681 | return; |
682 | } | |
683 | else | |
684 | { | |
49b82a1d | 685 | GlobalLogger.info() << LogPrefix << "DNS resolving timed out"; |
cd71d095 | 686 | schedule_retry(recursion_count); |
e18c1337 CH |
687 | } |
688 | } | |
689 | ||
96779587 | 690 | |
cd71d095 | 691 | void DnsResolver::schedule_retry(const int recursion_count) |
e18c1337 | 692 | { |
23f51766 | 693 | // cancel timers |
e18c1337 CH |
694 | ResolveTimeoutTimer.cancel(); |
695 | PauseBeforeRetryTimer.cancel(); | |
36ad976b | 696 | |
96779587 CH |
697 | // increment timer |
698 | ++RetryCount; | |
699 | ||
923626c0 CH |
700 | if ( RetryCount > DnsMaster::get_instance() |
701 | ->get_max_address_resolution_attempts() ) | |
e18c1337 CH |
702 | { // too many re-tries |
703 | GlobalLogger.info() << LogPrefix << "Not scheduling a retry since " | |
704 | << "RetryCount " << RetryCount << " too high"; | |
cd71d095 CH |
705 | handle_unavailable(recursion_count); // will call stop_trying |
706 | } // --> reset RetryCount | |
96779587 CH |
707 | else |
708 | { // schedule retry | |
e18c1337 CH |
709 | GlobalLogger.info() << LogPrefix << "Scheduling a retry (RetryCount=" |
710 | << RetryCount << ")"; | |
96779587 | 711 | PauseBeforeRetryTimer.expires_from_now( |
4e7b6ff9 | 712 | seconds(Config::PauseBeforeRetrySeconds)); |
96779587 | 713 | PauseBeforeRetryTimer.async_wait( |
4e7b6ff9 | 714 | boost::bind( &DnsResolver::wait_timer_timeout_handler, |
cd71d095 CH |
715 | this, recursion_count, |
716 | boost::asio::placeholders::error) ); | |
96779587 CH |
717 | } |
718 | } | |
719 | ||
cd71d095 | 720 | void DnsResolver::wait_timer_timeout_handler( const int recursion_count, |
96779587 CH |
721 | const boost::system::error_code &error) |
722 | { | |
723 | if ( error == boost::asio::error::operation_aborted ) // cancelled | |
e18c1337 CH |
724 | { // assume that our code cancelled this timer, so callbacks will be |
725 | // taken care of! | |
fd62d09f CH |
726 | GlobalLogger.debug() << LogPrefix |
727 | << "Resolve wait timer was cancelled! "; | |
e18c1337 | 728 | } |
96779587 | 729 | else if (error) |
e18c1337 CH |
730 | { // not sure what to do here, but callers waiting forever for a callback |
731 | // is probably the worst thing to happen, so call finalize_resolve | |
49b82a1d | 732 | GlobalLogger.info() << LogPrefix |
e18c1337 CH |
733 | << "resolve wait handler received error " |
734 | << error << "! Try to finalize resolve"; | |
735 | bool was_success = false; | |
cd71d095 | 736 | finalize_resolve(was_success, recursion_count); |
e18c1337 CH |
737 | } |
738 | else if ( OperationCancelled ) | |
739 | { // async_resolve was cancelled --> callbacks already called | |
740 | GlobalLogger.info() << LogPrefix | |
741 | << "Ignoring waiting timeout since we were cancelled"; | |
742 | return; | |
743 | } | |
96779587 CH |
744 | else |
745 | { | |
e91538f0 | 746 | GlobalLogger.info() << LogPrefix << "Done waiting --> re-try resolve"; |
fd62d09f | 747 | IsResolving = false; // will be set to true immediately in do_resolve |
cd71d095 | 748 | do_resolve(recursion_count); |
96779587 | 749 | } |
36ad976b CH |
750 | } |
751 | ||
752 | ||
96779587 CH |
753 | //============================================================================== |
754 | // RETRIEVAL | |
755 | //============================================================================== | |
756 | ||
26b0f687 | 757 | HostAddress DnsResolver::get_next_ip(bool check_up_to_date) |
36ad976b CH |
758 | { |
759 | // get cached data | |
26b0f687 | 760 | // (do not use arg check_up_to_date here in order to give NextIpIndex |
fd62d09f | 761 | // a chance to stay above number of outdated IPs) |
e18c1337 | 762 | HostAddressVec cached_data = ResolverBase::get_cached_ips_recursively(); |
96779587 CH |
763 | |
764 | // if no results cached, return default-constructed HostAddress (0.0.0.0) | |
26b0f687 | 765 | HostAddress return_candidate; |
96779587 | 766 | if ( cached_data.empty() ) |
4e7b6ff9 | 767 | { |
26b0f687 CH |
768 | GlobalLogger.debug() << LogPrefix << "Get next IP: nothing cached"; |
769 | return return_candidate; | |
4e7b6ff9 | 770 | } |
36ad976b | 771 | |
fd62d09f | 772 | std::size_t n_iter = 0; |
26b0f687 CH |
773 | std::size_t n_ips = cached_data.size(); |
774 | uint32_t ttl_thresh = static_cast<uint32_t>( DnsMaster::get_instance() | |
775 | ->get_resolved_ip_ttl_threshold() ); | |
36ad976b | 776 | |
26b0f687 CH |
777 | GlobalLogger.info() << LogPrefix << "Get next IP from cached result of " |
778 | << n_ips << " IPs; first index to consider is " << NextIpIndex | |
72be9e7d | 779 | << "; TTL thresh=" << ttl_thresh << "s is used: " << check_up_to_date; |
26b0f687 CH |
780 | |
781 | // loop until we have found a cached result (that is up to date) | |
782 | // or until we have tried all cached IPs | |
783 | while (true) | |
784 | { | |
785 | // check index since cache size may have changed since last call | |
786 | if (NextIpIndex >= n_ips) | |
72be9e7d CH |
787 | { |
788 | GlobalLogger.debug() << LogPrefix << "Reset NextIpIndex"; | |
26b0f687 | 789 | NextIpIndex = 0; |
72be9e7d | 790 | } |
26b0f687 | 791 | else if ( n_iter >= n_ips) |
72be9e7d CH |
792 | { |
793 | GlobalLogger.debug() << LogPrefix << "No IP found"; | |
26b0f687 | 794 | return HostAddress(); // have checked all candidates |
72be9e7d | 795 | } |
26b0f687 CH |
796 | else |
797 | { // there are candidates left to consider | |
fd62d09f CH |
798 | GlobalLogger.debug() << LogPrefix << "Check IP candidate at index " |
799 | << NextIpIndex; | |
26b0f687 CH |
800 | return_candidate = cached_data[NextIpIndex++]; |
801 | if (!check_up_to_date) | |
fd62d09f CH |
802 | { |
803 | GlobalLogger.debug() << LogPrefix << "not checking ttl, accept"; | |
26b0f687 | 804 | return return_candidate; |
fd62d09f CH |
805 | } |
806 | else if (return_candidate.get_ttl().get_updated_value() | |
26b0f687 | 807 | > ttl_thresh) |
fd62d09f CH |
808 | { |
809 | GlobalLogger.debug() << LogPrefix << "is up to date, accept"; | |
72be9e7d | 810 | return return_candidate; |
fd62d09f | 811 | } |
26b0f687 | 812 | else |
fd62d09f CH |
813 | { |
814 | GlobalLogger.debug() << LogPrefix << "is out of date (" | |
815 | << return_candidate.get_ttl().get_updated_value() | |
816 | << "s <= " << ttl_thresh << "s), continue"; | |
26b0f687 | 817 | ++n_iter; |
fd62d09f | 818 | } |
26b0f687 CH |
819 | } |
820 | } | |
36ad976b CH |
821 | } |
822 | ||
923626c0 CH |
823 | bool DnsResolver::have_up_to_date_ip() |
824 | { | |
fd62d09f | 825 | return get_resolved_ip_count(true) > 0; |
923626c0 CH |
826 | } |
827 | ||
fd62d09f | 828 | int DnsResolver::get_resolved_ip_count(const bool check_up_to_date) |
923626c0 | 829 | { |
fd62d09f CH |
830 | // run with empty hostname --> uses internal var Hostname |
831 | return ResolverBase::get_cached_ips_recursively("",check_up_to_date).size(); | |
923626c0 CH |
832 | } |
833 |