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1 : // Copyright (c) 2012-2021 Made to Order Software Corp. All Rights Reserved
2 : //
3 : // https://snapwebsites.org/project/eventdispatcher
4 : // contact@m2osw.com
5 : //
6 : // This program is free software; you can redistribute it and/or modify
7 : // it under the terms of the GNU General Public License as published by
8 : // the Free Software Foundation; either version 2 of the License, or
9 : // (at your option) any later version.
10 : //
11 : // This program is distributed in the hope that it will be useful,
12 : // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 : // GNU General Public License for more details.
15 : //
16 : // You should have received a copy of the GNU General Public License along
17 : // with this program; if not, write to the Free Software Foundation, Inc.,
18 : // 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 :
20 : /** \file
21 : * \brief Implementation of the Snap Communicator class.
22 : *
23 : * This class wraps the C poll() interface in a C++ object with many types
24 : * of objects:
25 : *
26 : * \li Server Connections; for software that want to offer a port to
27 : * which clients can connect to; the server will call accept()
28 : * once a new client connection is ready; this results in a
29 : * Server/Client connection object
30 : * \li Client Connections; for software that want to connect to
31 : * a server; these expect the IP address and port to connect to
32 : * \li Server/Client Connections; for the server when it accepts a new
33 : * connection; in this case the server gets a socket from accept()
34 : * and creates one of these objects to handle the connection
35 : *
36 : * Using the poll() function is the easiest and allows us to listen
37 : * on pretty much any number of sockets (on my server it is limited
38 : * at 16,768 and frankly over 1,000 we probably will start to have
39 : * real slowness issues on small VPN servers.)
40 : */
41 :
42 : // to get the POLLRDHUP definition
43 : #ifndef _GNU_SOURCE
44 : #define _GNU_SOURCE
45 : #endif
46 :
47 :
48 : // self
49 : //
50 : #include "eventdispatcher/local_stream_blocking_client_message_connection.h"
51 :
52 : #include "eventdispatcher/exception.h"
53 :
54 :
55 : // snaplogger lib
56 : //
57 : #include <snaplogger/message.h>
58 :
59 :
60 : // snapdev lib
61 : //
62 : #include <snapdev/not_used.h>
63 :
64 :
65 : // C++ lib
66 : //
67 : #include <cstring>
68 :
69 :
70 : // C lib
71 : //
72 : #include <poll.h>
73 : #include <sys/resource.h>
74 :
75 :
76 : // last include
77 : //
78 : #include <snapdev/poison.h>
79 :
80 :
81 :
82 : namespace ed
83 : {
84 :
85 :
86 :
87 : /** \brief Blocking client message connection.
88 : *
89 : * This object allows you to create a blocking, generally temporary
90 : * one message connection client. This is specifically used with
91 : * the snaplock daemon, but it can be used for other things too as
92 : * required.
93 : *
94 : * The connection is expected to be used as shown in the following
95 : * example which is how it is used to implement the LOCK through
96 : * our snaplock daemons.
97 : *
98 : * \code
99 : * class my_blocking_connection
100 : * : public ed::local_stream_blocking_client_message_connection
101 : * {
102 : * public:
103 : * my_blocking_connection(std::string const & addr, int port, mode_t mode)
104 : * : local_stream_blocking_client_message_connection(addr, port, mode)
105 : * {
106 : * // need to register with communicator
107 : * message register_message;
108 : * register_message.set_command("REGISTER");
109 : * ...
110 : * blocking_connection.send_message(register_message);
111 : *
112 : * run();
113 : * }
114 : *
115 : * ~my_blocking_connection()
116 : * {
117 : * // done, send UNLOCK and then make sure to unregister
118 : * message unlock_message;
119 : * unlock_message.set_command("UNLOCK");
120 : * ...
121 : * blocking_connection.send_message(unlock_message);
122 : *
123 : * message unregister_message;
124 : * unregister_message.set_command("UNREGISTER");
125 : * ...
126 : * blocking_connection.send_message(unregister_message);
127 : * }
128 : *
129 : * // now that we have a dispatcher, this would probably use
130 : * // that mechanism instead of a list of if()/else if()
131 : * //
132 : * // Please, consider using the dispatcher instead
133 : * //
134 : * virtual void process_message(message const & message)
135 : * {
136 : * QString const command(message.get_command());
137 : * if(command == "LOCKED")
138 : * {
139 : * // the lock worked, release hand back to the user
140 : * done();
141 : * }
142 : * else if(command == "READY")
143 : * {
144 : * // the REGISTER worked
145 : * // send the LOCK now
146 : * message lock_message;
147 : * lock_message.set_command("LOCK");
148 : * ...
149 : * blocking_connection.send_message(lock_message);
150 : * }
151 : * else if(command == "HELP")
152 : * {
153 : * // snapcommunicator wants us to tell it what commands
154 : * // we accept
155 : * message commands_message;
156 : * commands_message.set_command("COMMANDS");
157 : * ...
158 : * blocking_connection.send_message(commands_message);
159 : * }
160 : * }
161 : * };
162 : * my_blocking_connection blocking_connection("127.0.0.1", 4040);
163 : *
164 : * // then we can send a message to the service we are interested in
165 : * my_blocking_connection.send_message(my_message);
166 : *
167 : * // now we call run() waiting for a reply
168 : * my_blocking_connection.run();
169 : * \endcode
170 : *
171 : * \param[in] addr The address to connect to.
172 : * \param[in] port The port to connect at.
173 : * \param[in] mode The mode used to connect.
174 : */
175 0 : local_stream_blocking_client_message_connection::local_stream_blocking_client_message_connection(
176 : addr::unix const & address
177 : , bool const blocking
178 0 : , bool const close_on_exec)
179 : : local_stream_client_message_connection(
180 : address
181 : , blocking
182 0 : , close_on_exec)
183 : {
184 0 : }
185 :
186 :
187 : /** \brief Blocking run on the connection.
188 : *
189 : * This function reads the incoming messages and calls process_message()
190 : * on each one of them, in a blocking manner.
191 : *
192 : * If you called mark_done() before, the done flag is reset back to false.
193 : * You will have to call mark_done() again if you again receive a message
194 : * that is expected to end the loop.
195 : *
196 : * \note
197 : * Internally, the function actually calls process_line() which transforms
198 : * the line in a message and in turn calls process_message().
199 : */
200 0 : void local_stream_blocking_client_message_connection::run()
201 : {
202 0 : mark_not_done();
203 :
204 0 : do
205 : {
206 : for(;;)
207 : {
208 : // TBD: can the socket become -1 within the read() loop?
209 : // (i.e. should not that be just outside of the for(;;)?)
210 : //
211 0 : struct pollfd fd;
212 0 : fd.events = POLLIN | POLLPRI | POLLRDHUP;
213 0 : fd.fd = get_socket();
214 0 : if(fd.fd < 0
215 0 : || !is_enabled())
216 : {
217 : // invalid socket
218 0 : process_error();
219 0 : return;
220 : }
221 :
222 : // at this time, this class is used with the lock and
223 : // the lock has a timeout so we need to block at most
224 : // for that amount of time and not forever (presumably
225 : // the snaplock would send us a LOCKFAILED marked with
226 : // a "timeout" parameter, but we cannot rely on the
227 : // snaplock being there and responding as expected.)
228 : //
229 : // calculate the number of microseconds and then convert
230 : // them to milliseconds for poll()
231 : //
232 0 : std::int64_t const next_timeout_timestamp(save_timeout_timestamp());
233 0 : std::int64_t const now(get_current_date());
234 0 : std::int64_t const timeout((next_timeout_timestamp - now) / 1000);
235 0 : if(timeout <= 0)
236 : {
237 : // timed out
238 : //
239 0 : process_timeout();
240 0 : if(is_done())
241 : {
242 0 : return;
243 : }
244 0 : SNAP_LOG_FATAL
245 0 : << "blocking connection timed out."
246 : << SNAP_LOG_SEND;
247 : throw event_dispatcher_runtime_error(
248 : "local_stream_blocking_client_message_connection::run(): blocking"
249 0 : " connection timed out.");
250 : }
251 0 : errno = 0;
252 0 : fd.revents = 0; // probably useless... (kernel should clear those)
253 0 : int const r(::poll(&fd, 1, timeout));
254 0 : if(r < 0)
255 : {
256 : // r < 0 means an error occurred
257 : //
258 0 : if(errno == EINTR)
259 : {
260 : // Note: if the user wants to prevent this error, he should
261 : // use the signal with the Unix signals that may
262 : // happen while calling poll().
263 : //
264 : throw event_dispatcher_runtime_error(
265 : "local_stream_blocking_client_message_connection::run():"
266 : " EINTR occurred while in poll() -- interrupts"
267 0 : " are not supported yet though.");
268 : }
269 0 : if(errno == EFAULT)
270 : {
271 : throw event_dispatcher_runtime_error(
272 : "local_stream_blocking_client_message_connection::run():"
273 0 : " buffer was moved out of our address space?");
274 : }
275 0 : if(errno == EINVAL)
276 : {
277 : // if this is really because nfds is too large then it may be
278 : // a "soft" error that can be fixed; that being said, my
279 : // current version is 16K files which frankly when we reach
280 : // that level we have a problem...
281 : //
282 0 : rlimit rl;
283 0 : getrlimit(RLIMIT_NOFILE, &rl);
284 : throw event_dispatcher_invalid_parameter(
285 : "local_stream_blocking_client_message_connection::run():"
286 : " too many file fds for poll, limit is"
287 : " currently "
288 0 : + std::to_string(rl.rlim_cur)
289 0 : + ", your kernel top limit is "
290 0 : + std::to_string(rl.rlim_max)
291 0 : + ".");
292 : }
293 0 : if(errno == ENOMEM)
294 : {
295 : throw event_dispatcher_runtime_error(
296 : "local_stream_blocking_client_message_connection::run():"
297 0 : " poll() failed because of memory.");
298 : }
299 0 : int const e(errno);
300 : throw event_dispatcher_invalid_parameter(
301 : "local_stream_blocking_client_message_connection::run():"
302 : " poll() failed with error "
303 0 : + std::to_string(e)
304 0 : + " -- "
305 0 : + strerror(e));
306 : }
307 :
308 0 : if((fd.revents & (POLLIN | POLLPRI)) != 0)
309 : {
310 : // read one character at a time otherwise we would be
311 : // blocked forever
312 : //
313 0 : char buf[2];
314 0 : int const size(::read(fd.fd, buf, 1));
315 0 : if(size != 1)
316 : {
317 : // invalid read
318 : //
319 0 : process_error();
320 : throw event_dispatcher_invalid_parameter(
321 : "local_stream_blocking_client_message_connection::run():"
322 : " read() failed reading data from socket"
323 : " (return value = "
324 0 : + std::to_string(size)
325 0 : + ").");
326 : }
327 0 : if(buf[0] == '\n')
328 : {
329 : // end of a line, we got a whole message in our buffer
330 : // notice that we do not add the '\n' to line
331 : //
332 0 : break;
333 : }
334 0 : buf[1] = '\0';
335 0 : f_line += buf;
336 : }
337 0 : if((fd.revents & POLLERR) != 0)
338 : {
339 0 : process_error();
340 0 : return;
341 : }
342 0 : if((fd.revents & (POLLHUP | POLLRDHUP)) != 0)
343 : {
344 0 : process_hup();
345 0 : return;
346 : }
347 0 : if((fd.revents & POLLNVAL) != 0)
348 : {
349 0 : process_invalid();
350 0 : return;
351 : }
352 0 : }
353 0 : process_line(f_line);
354 0 : f_line.clear();
355 : }
356 0 : while(!is_done());
357 : }
358 :
359 :
360 : /** \brief Quick peek on the connection.
361 : *
362 : * This function checks for incoming messages and calls process_message()
363 : * on each one of them. If no messages are found on the pipe, then the
364 : * function returns immediately.
365 : *
366 : * \note
367 : * Internally, the function actually calls process_line() which transforms
368 : * the line in a message and in turn calls process_message().
369 : */
370 0 : void local_stream_blocking_client_message_connection::peek()
371 : {
372 0 : do
373 : {
374 : for(;;)
375 : {
376 0 : pollfd fd;
377 0 : fd.events = POLLIN | POLLPRI | POLLRDHUP;
378 0 : fd.fd = get_socket();
379 0 : if(fd.fd < 0
380 0 : || !is_enabled())
381 : {
382 : // invalid socket
383 0 : process_error();
384 0 : return;
385 : }
386 :
387 0 : errno = 0;
388 0 : fd.revents = 0; // probably useless... (kernel should clear those)
389 0 : int const r(::poll(&fd, 1, 0));
390 0 : if(r < 0)
391 : {
392 : // r < 0 means an error occurred
393 : //
394 0 : if(errno == EINTR)
395 : {
396 : // Note: if the user wants to prevent this error, he should
397 : // use the signal with the Unix signals that may
398 : // happen while calling poll().
399 : //
400 : throw event_dispatcher_runtime_error(
401 : "local_stream_blocking_client_message_connection::run():"
402 : " EINTR occurred while in poll() -- interrupts"
403 0 : " are not supported yet though");
404 : }
405 0 : if(errno == EFAULT)
406 : {
407 : throw event_dispatcher_invalid_parameter(
408 : "local_stream_blocking_client_message_connection::run():"
409 0 : " buffer was moved out of our address space?");
410 : }
411 0 : if(errno == EINVAL)
412 : {
413 : // if this is really because nfds is too large then it may be
414 : // a "soft" error that can be fixed; that being said, my
415 : // current version is 16K files which frankly when we reach
416 : // that level we have a problem...
417 : //
418 0 : struct rlimit rl;
419 0 : getrlimit(RLIMIT_NOFILE, &rl);
420 : throw event_dispatcher_invalid_parameter(
421 : "local_stream_blocking_client_message_connection::run():"
422 : " too many file fds for poll, limit is currently "
423 0 : + std::to_string(rl.rlim_cur)
424 0 : + ", your kernel top limit is "
425 0 : + std::to_string(rl.rlim_max));
426 : }
427 0 : if(errno == ENOMEM)
428 : {
429 : throw event_dispatcher_runtime_error(
430 : "local_stream_blocking_client_message_connection::run():"
431 0 : " poll() failed because of memory");
432 : }
433 0 : int const e(errno);
434 : throw event_dispatcher_runtime_error(
435 : "local_stream_blocking_client_message_connection::run():"
436 : " poll() failed with error "
437 0 : + std::to_string(e)
438 0 : + " -- "
439 0 : + strerror(e));
440 : }
441 :
442 0 : if(r == 0)
443 : {
444 0 : return;
445 : }
446 :
447 0 : if((fd.revents & (POLLIN | POLLPRI)) != 0)
448 : {
449 : // read one character at a time otherwise we would be
450 : // blocked forever
451 : //
452 0 : char buf[2];
453 0 : int const size(::read(fd.fd, buf, 1));
454 0 : if(size != 1)
455 : {
456 : // invalid read
457 0 : process_error();
458 : throw event_dispatcher_runtime_error(
459 : "local_stream_blocking_client_message_connection::run():"
460 : " read() failed reading data from socket (return"
461 : " value = "
462 0 : + std::to_string(size)
463 0 : + ")");
464 : }
465 0 : if(buf[0] == '\n')
466 : {
467 : // end of a line, we got a whole message in our buffer
468 : // notice that we do not add the '\n' to line
469 0 : break;
470 : }
471 0 : buf[1] = '\0';
472 0 : f_line += buf;
473 : }
474 0 : if((fd.revents & POLLERR) != 0)
475 : {
476 0 : process_error();
477 0 : return;
478 : }
479 0 : if((fd.revents & (POLLHUP | POLLRDHUP)) != 0)
480 : {
481 0 : process_hup();
482 0 : return;
483 : }
484 0 : if((fd.revents & POLLNVAL) != 0)
485 : {
486 0 : process_invalid();
487 0 : return;
488 : }
489 0 : }
490 0 : process_line(f_line);
491 0 : f_line.clear();
492 : }
493 0 : while(!is_done());
494 : }
495 :
496 :
497 : /** \brief Send the specified message to the connection on the other end.
498 : *
499 : * This function sends the specified message to the other side of the
500 : * socket connection. If the write somehow fails, then the function
501 : * returns false.
502 : *
503 : * The function blocks until the entire message was written to the
504 : * socket.
505 : *
506 : * \param[in] message The message to send to the connection.
507 : * \param[in] cache Whether to cache the message if it cannot be sent
508 : * immediately (ignored at the moment.)
509 : *
510 : * \return true if the message was sent successfully, false otherwise.
511 : */
512 0 : bool local_stream_blocking_client_message_connection::send_message(message const & msg, bool cache)
513 : {
514 0 : snap::NOT_USED(cache);
515 :
516 0 : int const s(get_socket());
517 0 : if(s >= 0)
518 : {
519 : // transform the message to a string and write to the socket
520 : // the writing is blocking and thus fully synchronous so the
521 : // function blocks until the message gets fully sent
522 : //
523 : // WARNING: we cannot use f_connection.write() because that one
524 : // is asynchronous (at least, it writes to a buffer
525 : // and not directly to the socket!)
526 : //
527 0 : std::string buf(msg.to_message());
528 0 : buf += '\n';
529 0 : return ::write(s, buf.c_str(), buf.length()) == static_cast<ssize_t>(buf.length());
530 : }
531 :
532 0 : return false;
533 : }
534 :
535 :
536 :
537 :
538 :
539 6 : } // namespace ed
540 : // vim: ts=4 sw=4 et
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