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1 : // Copyright (c) 2012-2022 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
17 : // along with this program; if not, write to the Free Software
18 : // Foundation, Inc., 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 :
43 : // self
44 : //
45 : #include "eventdispatcher/tcp_client_buffer_connection.h"
46 :
47 : #include "eventdispatcher/utils.h"
48 :
49 :
50 : // snaplogger
51 : //
52 : #include <snaplogger/message.h>
53 :
54 :
55 : // C++
56 : //
57 : #include <algorithm>
58 : #include <cstring>
59 :
60 :
61 : // last include
62 : //
63 : #include <snapdev/poison.h>
64 :
65 :
66 :
67 : namespace ed
68 : {
69 :
70 :
71 :
72 : /** \brief Initialize a client socket.
73 : *
74 : * The client socket gets initialized with the specified 'socket'
75 : * parameter.
76 : *
77 : * This constructor creates a writer connection too. This gives you
78 : * a read/write connection. You can get the writer with the writer()
79 : * function. So you may write data with:
80 : *
81 : * \code
82 : * my_reader.writer().write(buf, buf_size);
83 : * \endcode
84 : *
85 : * \param[in] address The address to connect to.
86 : * \param[in] mode The mode to connect as (PLAIN or SECURE).
87 : * \param[in] blocking If true, keep a blocking socket, other non-blocking.
88 : */
89 0 : tcp_client_buffer_connection::tcp_client_buffer_connection(
90 : addr::addr const & address
91 : , mode_t const mode
92 0 : , bool const blocking)
93 0 : : tcp_client_connection(address, mode)
94 : {
95 0 : if(!blocking)
96 : {
97 0 : non_blocking();
98 : }
99 0 : }
100 :
101 :
102 : /** \brief Check whether this connection still has some input in its buffer.
103 : *
104 : * This function returns true if there is partial incoming data in this
105 : * object's buffer.
106 : *
107 : * \return true if some buffered input is waiting for completion.
108 : */
109 0 : bool tcp_client_buffer_connection::has_input() const
110 : {
111 0 : return !f_line.empty();
112 : }
113 :
114 :
115 :
116 : /** \brief Check whether this connection still has some output in its buffer.
117 : *
118 : * This function returns true if there is still some output in the client
119 : * buffer. Output is added by the write() function, which is called by
120 : * the send_message() function.
121 : *
122 : * \return true if some buffered output is waiting to be sent out.
123 : */
124 0 : bool tcp_client_buffer_connection::has_output() const
125 : {
126 0 : return !f_output.empty();
127 : }
128 :
129 :
130 :
131 : /** \brief Write data to the connection.
132 : *
133 : * This function can be used to send data to this TCP/IP connection.
134 : * The data is bufferized and as soon as the connection can WRITE
135 : * to the socket, it will wake up and send the data. In other words,
136 : * we cannot just sleep and wait for an answer. The transfer will
137 : * be asynchronous.
138 : *
139 : * \todo
140 : * Optimization: look into writing the \p data buffer directly in
141 : * the socket if the f_output cache is empty. If that works then
142 : * we can completely bypass our intermediate cache. This works only
143 : * if we make sure that the socket is non-blocking, though.
144 : *
145 : * \todo
146 : * Determine whether we may end up with really large buffers that
147 : * grow for a long time. This function only inserts and the
148 : * process_signal() function only reads some of the bytes but it
149 : * does not reduce the size of the buffer until all the data was
150 : * sent.
151 : *
152 : * \param[in] data The pointer to the buffer of data to be sent.
153 : * \param[out] length The number of bytes to send.
154 : *
155 : * \return The number of bytes that were saved in our buffer, 0 if
156 : * no data was written to the buffer (i.e. length is zero or data
157 : * is a null pointer). Or -1 on an error (i.e. the socket is closed).
158 : */
159 0 : ssize_t tcp_client_buffer_connection::write(void const * data, size_t length)
160 : {
161 0 : if(get_socket() == -1)
162 : {
163 0 : errno = EBADF;
164 0 : return -1;
165 : }
166 :
167 0 : if(data != nullptr && length > 0)
168 : {
169 0 : char const * d(reinterpret_cast<char const *>(data));
170 0 : f_output.insert(f_output.end(), d, d + length);
171 0 : return length;
172 : }
173 :
174 0 : return 0;
175 : }
176 :
177 :
178 : /** \brief The buffer is a writer when the output buffer is not empty.
179 : *
180 : * This function returns true as long as the output buffer of this
181 : * client connection is not empty.
182 : *
183 : * \return true if the output buffer is not empty, false otherwise.
184 : */
185 0 : bool tcp_client_buffer_connection::is_writer() const
186 : {
187 0 : return get_socket() != -1 && !f_output.empty();
188 : }
189 :
190 :
191 : /** \brief Instantiation of process_read().
192 : *
193 : * This function reads incoming data from a socket.
194 : *
195 : * The function is what manages our low level TCP/IP connection protocol
196 : * which is to read one line of data (i.e. bytes up to the next '\\n'
197 : * character; note that '\\r' are not understood.)
198 : *
199 : * Once a complete line of data was read, it is converted to UTF-8 and
200 : * sent to the next layer using the process_line() function passing
201 : * the line it just read (without the '\\n') to that callback.
202 : *
203 : * \sa process_write()
204 : * \sa process_line()
205 : */
206 0 : void tcp_client_buffer_connection::process_read()
207 : {
208 : // we read one character at a time until we get a '\n'
209 : // since we have a non-blocking socket we can read as
210 : // much as possible and then check for a '\n' and keep
211 : // any extra data in a cache.
212 : //
213 0 : if(get_socket() != -1)
214 : {
215 0 : int count_lines(0);
216 0 : std::int64_t const date_limit(get_current_date() + get_processing_time_limit());
217 0 : std::vector<char> buffer;
218 0 : buffer.resize(1024);
219 : for(;;)
220 : {
221 0 : errno = 0;
222 0 : ssize_t const r(read(&buffer[0], buffer.size()));
223 0 : if(r > 0)
224 : {
225 0 : for(ssize_t position(0); position < r; )
226 : {
227 0 : std::vector<char>::const_iterator it(std::find(buffer.begin() + position, buffer.begin() + r, '\n'));
228 0 : if(it == buffer.begin() + r)
229 : {
230 : // no newline, just add the whole thing
231 0 : f_line += std::string(&buffer[position], r - position);
232 0 : break; // do not waste time, we know we are done
233 : }
234 :
235 : // retrieve the characters up to the newline
236 : // character and process the line
237 : //
238 0 : f_line += std::string(&buffer[position], it - buffer.begin() - position);
239 0 : process_line(f_line);
240 0 : ++count_lines;
241 :
242 : // done with that line
243 : //
244 0 : f_line.clear();
245 :
246 : // we had a newline, we may still have some data
247 : // in that buffer; (+1 to skip the '\n' itself)
248 : //
249 0 : position = it - buffer.begin() + 1;
250 : }
251 :
252 : // when we reach here all the data read in `buffer` is
253 : // now either fully processed or in f_line
254 : //
255 : // TODO: change the way this works so we can test the
256 : // limit after each process_line() call
257 : //
258 0 : if(count_lines >= get_event_limit()
259 0 : || get_current_date() >= date_limit)
260 : {
261 : // we reach one or both limits, stop processing so
262 : // the other events have a chance to run
263 : //
264 0 : break;
265 : }
266 : }
267 0 : else if(r == 0 || errno == 0 || errno == EAGAIN || errno == EWOULDBLOCK)
268 : {
269 : // no more data available at this time
270 : break;
271 : }
272 : else //if(r < 0)
273 : {
274 : // TODO: do something about the error
275 0 : int const e(errno);
276 0 : SNAP_LOG_ERROR
277 0 : << "an error occurred while reading from socket (errno: "
278 : << e
279 : << " -- "
280 0 : << strerror(e)
281 : << ")."
282 : << SNAP_LOG_SEND;
283 0 : process_error();
284 0 : return;
285 : }
286 0 : }
287 : }
288 :
289 : // process next level too
290 0 : tcp_client_connection::process_read();
291 : }
292 :
293 :
294 : /** \brief Instantiation of process_write().
295 : *
296 : * This function writes outgoing data to a socket.
297 : *
298 : * This function manages our own internal cache, which we use to allow
299 : * for out of synchronization (non-blocking) output.
300 : *
301 : * When the output buffer goes empty, this function calls the
302 : * process_empty_buffer() callback.
303 : *
304 : * \sa write()
305 : * \sa process_read()
306 : * \sa process_empty_buffer()
307 : */
308 0 : void tcp_client_buffer_connection::process_write()
309 : {
310 0 : if(get_socket() != -1)
311 : {
312 0 : errno = 0;
313 0 : ssize_t const r(tcp_client_connection::write(&f_output[f_position], f_output.size() - f_position));
314 0 : if(r > 0)
315 : {
316 : // some data was written
317 0 : f_position += r;
318 0 : if(f_position >= f_output.size())
319 : {
320 0 : f_output.clear();
321 0 : f_position = 0;
322 0 : process_empty_buffer();
323 : }
324 : }
325 0 : else if(r < 0 && errno != 0 && errno != EAGAIN && errno != EWOULDBLOCK)
326 : {
327 : // connection is considered bad, generate an error
328 : //
329 0 : int const e(errno);
330 0 : SNAP_LOG_ERROR
331 : << "an error occurred while writing to socket of \""
332 0 : << get_name()
333 0 : << "\" (errno: "
334 : << e
335 : << " -- "
336 0 : << strerror(e)
337 : << ")."
338 : << SNAP_LOG_SEND;
339 0 : process_error();
340 0 : return;
341 : }
342 : }
343 :
344 : // process next level too
345 0 : tcp_client_connection::process_write();
346 : }
347 :
348 :
349 : /** \brief The hang up event occurred.
350 : *
351 : * This function closes the socket and then calls the previous level
352 : * hang up code which removes this connection from the communicator
353 : * object it was last added in.
354 : */
355 0 : void tcp_client_buffer_connection::process_hup()
356 : {
357 : // this connection is dead...
358 : //
359 0 : close();
360 :
361 : // process next level too
362 0 : tcp_client_connection::process_hup();
363 0 : }
364 :
365 :
366 : /** \fn tcp_client_buffer_connection::process_line(std::string const & line);
367 : * \brief Process a line of data.
368 : *
369 : * This is the default virtual class that can be overridden to implement
370 : * your own processing. By default this function does nothing.
371 : *
372 : * \note
373 : * At this point I implemented this function so one can instantiate
374 : * a tcp_server_client_buffer_connection without having to
375 : * derive it, although I do not think that is 100% proper.
376 : *
377 : * \param[in] line The line of data that was just read from the input
378 : * socket.
379 : */
380 :
381 :
382 :
383 6 : } // namespace ed
384 : // vim: ts=4 sw=4 et
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