1 /** @file
2 
3   Public VConnection declaration and associated declarations
4 
5   @section license License
6 
7   Licensed to the Apache Software Foundation (ASF) under one
8   or more contributor license agreements.  See the NOTICE file
9   distributed with this work for additional information
10   regarding copyright ownership.  The ASF licenses this file
11   to you under the Apache License, Version 2.0 (the
12   "License"); you may not use this file except in compliance
13   with the License.  You may obtain a copy of the License at
14 
15       http://www.apache.org/licenses/LICENSE-2.0
16 
17   Unless required by applicable law or agreed to in writing, software
18   distributed under the License is distributed on an "AS IS" BASIS,
19   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
20   See the License for the specific language governing permissions and
21   limitations under the License.
22 
23  */
24 
25 #pragma once
26 
27 #include "tscore/ink_platform.h"
28 #include "I_EventSystem.h"
29 
30 #if !defined(I_VIO_h)
31 #error "include I_VIO.h"
32 #endif
33 
34 #include <array>
35 
36 static constexpr int TS_VCONN_MAX_USER_ARG = 4;
37 
38 //
39 // Data Types
40 //
41 #define VCONNECTION_CACHE_DATA_BASE 0
42 #define VCONNECTION_NET_DATA_BASE 100
43 #define VCONNECTION_API_DATA_BASE 200
44 
45 //
46 // Event signals
47 //
48 
49 #define VC_EVENT_NONE EVENT_NONE
50 
51 /** When a Continuation is first scheduled on a processor. */
52 #define VC_EVENT_IMMEDIATE EVENT_IMMEDIATE
53 
54 #define VC_EVENT_READ_READY VC_EVENT_EVENTS_START
55 
56 /**
57   Any data in the associated buffer *will be written* when the
58   Continuation returns.
59 
60 */
61 #define VC_EVENT_WRITE_READY (VC_EVENT_EVENTS_START + 1)
62 
63 #define VC_EVENT_READ_COMPLETE (VC_EVENT_EVENTS_START + 2)
64 #define VC_EVENT_WRITE_COMPLETE (VC_EVENT_EVENTS_START + 3)
65 
66 /**
67   No more data (end of stream). It should be interpreted by a
68   protocol engine as either a COMPLETE or ERROR.
69 
70 */
71 #define VC_EVENT_EOS (VC_EVENT_EVENTS_START + 4)
72 
73 #define VC_EVENT_ERROR EVENT_ERROR
74 
75 /**
76   VC_EVENT_INACTIVITY_TIMEOUT indicates that the operation (read or write) has:
77     -# been enabled for more than the inactivity timeout period
78        (for a read, there has been space in the buffer)
79        (for a write, there has been data in the buffer)
80     -# no progress has been made
81        (for a read, no data has been read from the connection)
82        (for a write, no data has been written to the connection)
83 
84 */
85 #define VC_EVENT_INACTIVITY_TIMEOUT (VC_EVENT_EVENTS_START + 5)
86 
87 /**
88   Total time for some operation has been exceeded, regardless of any
89   intermediate progress.
90 
91 */
92 #define VC_EVENT_ACTIVE_TIMEOUT (VC_EVENT_EVENTS_START + 6)
93 
94 #define VC_EVENT_OOB_COMPLETE (VC_EVENT_EVENTS_START + 7)
95 
96 //
97 // Event names
98 //
99 
100 //
101 // VC_EVENT_READ_READ occurs when data *has been written* into
102 // the associated buffer.
103 //
104 // VC_EVENT_ERROR indicates that some error has occurred.  The
105 // "data" will be either 0 if the errno is unavailable or errno.
106 //
107 // VC_EVENT_INTERVAL indicates that an interval timer has expired.
108 //
109 
110 //
111 // Event return codes
112 //
113 #define VC_EVENT_DONE CONTINUATION_DONE
114 #define VC_EVENT_CONT CONTINUATION_CONT
115 
116 //////////////////////////////////////////////////////////////////////////////
117 //
118 //      Support Data Structures
119 //
120 //////////////////////////////////////////////////////////////////////////////
121 
122 /** Used in VConnection::shutdown(). */
123 enum ShutdownHowTo_t {
124   IO_SHUTDOWN_READ = 0,
125   IO_SHUTDOWN_WRITE,
126   IO_SHUTDOWN_READWRITE,
127 };
128 
129 /** Used in VConnection::get_data(). */
130 enum TSApiDataType {
131   TS_API_DATA_READ_VIO = VCONNECTION_API_DATA_BASE,
132   TS_API_DATA_WRITE_VIO,
133   TS_API_DATA_OUTPUT_VC,
134   TS_API_DATA_CLOSED,
135   TS_API_DATA_LAST ///< Used by other classes to extend the enum values.
136 };
137 
138 extern "C" {
139 typedef struct tsapi_vio *TSVIO;
140 }
141 
142 /**
143   Base class for the connection classes that provide IO capabilities.
144 
145   The VConnection class is an abstract representation of a uni or
146   bi-directional data conduit returned by a Processor. In a sense,
147   they serve a similar purpose to file descriptors. A VConnection
148   is a pure base class that defines methods to perform stream IO.
149   It is also a Continuation that is called back from processors.
150 
151 */
152 class VConnection : public Continuation
153 {
154 public:
155   ~VConnection() override;
156 
157   /**
158     Read data from the VConnection.
159 
160     Called by a state machine to read data from the VConnection.
161     Processors implementing read functionality take out lock, put
162     new bytes on the buffer and call the continuation back before
163     releasing the lock in order to enable the state machine to
164     handle transfer schemes where the end of a given transaction
165     is marked by a special character (ie: NNTP).
166 
167     <b>Possible Event Codes</b>
168 
169     On the callback to the continuation, the VConnection may use
170     on of the following values for the event code:
171 
172     <table border="1">
173       <tr>
174         <td align="center"><b>Event code</b></td>
175         <td align="center"><b>Meaning</b></td>
176       </tr>
177       <tr>
178         <td>VC_EVENT_READ_READY</td>
179         <td>Data has been added to the buffer or the buffer is full</td>
180       </tr>
181       <tr>
182         <td>VC_EVENT_READ_COMPLETE</td>
183         <td>The amount of data indicated by 'nbytes' has been read into the
184             buffer</td>
185       </tr>
186       <tr>
187         <td>VC_EVENT_EOS</td>
188         <td>The stream being read from has been shutdown</td>
189       </tr>
190       <tr>
191         <td>VC_EVENT_ERROR</td>
192         <td>An error occurred during the read</td>
193       </tr>
194     </table>
195 
196     @param c Continuation to be called back with events.
197     @param nbytes Number of bytes to read. If unknown, nbytes must
198       be set to INT64_MAX.
199     @param buf buffer to read into.
200     @return VIO representing the scheduled IO operation.
201 
202   */
203   virtual VIO *do_io_read(Continuation *c = nullptr, int64_t nbytes = INT64_MAX, MIOBuffer *buf = nullptr) = 0;
204 
205   /**
206     Write data to the VConnection.
207 
208     This method is called by a state machine to write data to the
209     VConnection.
210 
211     <b>Possible Event Codes</b>
212 
213     On the callback to the continuation, the VConnection may use
214     on of the following event codes:
215 
216     <table border="1">
217       <tr>
218         <td align="center"><b>Event code</b></td>
219         <td align="center"><b>Meaning</b></td>
220       </tr>
221       <tr>
222         <td>VC_EVENT_WRITE_READY</td>
223         <td>Data was written from the reader or there are no bytes available
224         for the reader to write.</td>
225       </tr>
226       <tr>
227         <td>VC_EVENT_WRITE_COMPLETE</td>
228         <td>The amount of data indicated by 'nbytes' has been written to the
229             VConnection</td>
230       </tr>
231       <tr>
232         <td>VC_EVENT_INACTIVITY_TIMEOUT</td>
233         <td>No activity was performed for a certain period.</td>
234       </tr>
235       <tr>
236         <td>VC_EVENT_ACTIVE_TIMEOUT</td>
237         <td>Write operation continued beyond a time limit.</td>
238       </tr>
239       <tr>
240         <td>VC_EVENT_ERROR</td>
241         <td>An error occurred during the write</td>
242       </tr>
243     </table>
244 
245     @param c Continuation to be called back with events.
246     @param nbytes Number of bytes to write. If unknown, nbytes must
247       be set to INT64_MAX.
248     @param buf Reader whose data is to be read from.
249     @param owner
250     @return VIO representing the scheduled IO operation.
251 
252   */
253   virtual VIO *do_io_write(Continuation *c = nullptr, int64_t nbytes = INT64_MAX, IOBufferReader *buf = nullptr,
254                            bool owner = false) = 0;
255 
256   /**
257     Indicate that the VConnection is no longer needed.
258 
259     Once the state machine has finished using this VConnection, it
260     must call this function to indicate that the VConnection can
261     be deallocated.  After a close has been called, the VConnection
262     and underlying processor must not send any more events related
263     to this VConnection to the state machine. Likewise, the state
264     machine must not access the VConnection or any VIOs obtained
265     from it after calling this method.
266 
267     @param lerrno indicates where a close is a normal close or an
268       abort. The difference between a normal close and an abort
269       depends on the underlying type of the VConnection.
270 
271   */
272   virtual void do_io_close(int lerrno = -1) = 0;
273 
274   /**
275     Terminate one or both directions of the VConnection.
276 
277     Indicates that one or both sides of the VConnection should be
278     terminated. After this call is issued, no further I/O can be
279     done on the specified direction of the connection. The processor
280     must not send any further events (including timeout events) to
281     the state machine, and the state machine must not use any VIOs
282     from a shutdown direction of the connection. Even if both sides
283     of a connection are shutdown, the state machine must still call
284     do_io_close() when it wishes the VConnection to be deallocated.
285 
286     <b>Possible howto values</b>
287 
288     <table border="1">
289       <tr>
290         <td align="center"><b>Value</b></td>
291         <td align="center"><b>Meaning</b></td>
292       </tr>
293       <tr>
294         <td>IO_SHUTDOWN_READ</td>
295         <td>Indicates that this VConnection should not generate any more
296         read events</td>
297       </tr>
298       <tr>
299         <td>IO_SHUTDOWN_WRITE</td>
300         <td>Indicates that this VConnection should not generate any more
301         write events</td>
302       </tr>
303       <tr>
304         <td>IO_SHUTDOWN_READWRITE</td>
305         <td>Indicates that this VConnection should not generate any more
306         read nor write events</td>
307       </tr>
308     </table>
309 
310     @param howto Specifies which direction of the VConnection to
311       shutdown.
312 
313   */
314   virtual void do_io_shutdown(ShutdownHowTo_t howto) = 0;
315 
316   VConnection(ProxyMutex *aMutex);
317   VConnection(Ptr<ProxyMutex> &aMutex);
318 
319   // Private
320   // Set continuation on a given vio. The public interface
321   // is through VIO::set_continuation()
322   virtual void set_continuation(VIO *vio, Continuation *cont);
323 
324   // Reenable a given vio.  The public interface is through VIO::reenable
325   virtual void reenable(VIO *vio);
326   virtual void reenable_re(VIO *vio);
327 
328   /**
329     Convenience function to retrieve information from VConnection.
330 
331     This function is provided as a convenience for state machines
332     to transmit information from/to a VConnection without breaking
333     the VConnection abstraction. Its behavior varies depending on
334     the type of VConnection being used.
335 
336     @param id Identifier associated to interpret the data field
337     @param data Value or pointer with state machine or VConnection data.
338     @return True if the operation is successful.
339 
340   */
341   virtual bool
342   get_data(int id, void *data)
343   {
344     (void)id;
345     (void)data;
346     return false;
347   }
348 
349   /**
350     Convenience function to set information into the VConnection.
351 
352     This function is provided as a convenience for state machines
353     to transmit information from/to a VConnection without breaking
354     the VConnection abstraction. Its behavior varies depending on
355     the type of VConnection being used.
356 
357     @param id Identifier associated to interpret the data field.
358     @param data Value or pointer with state machine or VConnection data.
359     @return True if the operation is successful.
360 
361   */
362   virtual bool
363   set_data(int id, void *data)
364   {
365     (void)id;
366     (void)data;
367     return false;
368   }
369 
370 public:
371   /**
372     The error code from the last error.
373 
374     Indicates the last error on the VConnection. They are either
375     system error codes or from the InkErrno.h file.
376 
377   */
378   int lerrno;
379 };
380 
381 /**
382   Subclass of VConnection to provide support for user arguments
383 
384   Inherited by DummyVConnection (down to INKContInternal) and NetVConnection
385 */
386 class AnnotatedVConnection : public VConnection
387 {
388   using self_type  = AnnotatedVConnection;
389   using super_type = VConnection;
390 
391 public:
392   AnnotatedVConnection(ProxyMutex *aMutex) : super_type(aMutex){};
393   AnnotatedVConnection(Ptr<ProxyMutex> &aMutex) : super_type(aMutex){};
394 
395   void *
396   get_user_arg(unsigned ix) const
397   {
398     ink_assert(ix < user_args.size());
399     return this->user_args[ix];
400   };
401   void
402   set_user_arg(unsigned ix, void *arg)
403   {
404     ink_assert(ix < user_args.size());
405     user_args[ix] = arg;
406   };
407 
408 protected:
409   std::array<void *, TS_VCONN_MAX_USER_ARG> user_args{{nullptr}};
410 };
411 
412 struct DummyVConnection : public AnnotatedVConnection {
413   VIO *
414   do_io_write(Continuation * /* c ATS_UNUSED */, int64_t /* nbytes ATS_UNUSED */, IOBufferReader * /* buf ATS_UNUSED */,
415               bool /* owner ATS_UNUSED */) override
416   {
417     ink_assert(!"VConnection::do_io_write -- "
418                 "cannot use default implementation");
419     return nullptr;
420   }
421 
422   VIO *
423   do_io_read(Continuation * /* c ATS_UNUSED */, int64_t /* nbytes ATS_UNUSED */, MIOBuffer * /* buf ATS_UNUSED */) override
424   {
425     ink_assert(!"VConnection::do_io_read -- "
426                 "cannot use default implementation");
427     return nullptr;
428   }
429 
430   void
431   do_io_close(int /* alerrno ATS_UNUSED */) override
432   {
433     ink_assert(!"VConnection::do_io_close -- "
434                 "cannot use default implementation");
435   }
436 
437   void do_io_shutdown(ShutdownHowTo_t /* howto ATS_UNUSED */) override
438   {
439     ink_assert(!"VConnection::do_io_shutdown -- "
440                 "cannot use default implementation");
441   }
442 
443   DummyVConnection(ProxyMutex *m) : AnnotatedVConnection(m) {}
444 };
445