1/*
2 * Copyright (c) 2002-2004 Niels Provos <provos@citi.umich.edu>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 *    derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include <sys/types.h>
29
30#ifdef HAVE_CONFIG_H
31#include "config.h"
32#endif
33
34#ifdef HAVE_SYS_TIME_H
35#include <sys/time.h>
36#endif
37
38#include <errno.h>
39#include <stdio.h>
40#include <stdlib.h>
41#include <string.h>
42#ifdef HAVE_STDARG_H
43#include <stdarg.h>
44#endif
45
46#include "event.h"
47
48/* prototypes */
49
50void bufferevent_setwatermark(struct bufferevent *, short, size_t, size_t);
51void bufferevent_read_pressure_cb(struct evbuffer *, size_t, size_t, void *);
52
53static int
54bufferevent_add(struct event *ev, int timeout)
55{
56	struct timeval tv, *ptv = NULL;
57
58	if (timeout) {
59		timerclear(&tv);
60		tv.tv_sec = timeout;
61		ptv = &tv;
62	}
63
64	return (event_add(ev, ptv));
65}
66
67/*
68 * This callback is executed when the size of the input buffer changes.
69 * We use it to apply back pressure on the reading side.
70 */
71
72void
73bufferevent_read_pressure_cb(struct evbuffer *buf, size_t old, size_t now,
74    void *arg) {
75	struct bufferevent *bufev = arg;
76	/*
77	 * If we are below the watermark then reschedule reading if it's
78	 * still enabled.
79	 */
80	if (bufev->wm_read.high == 0 || now < bufev->wm_read.high) {
81		evbuffer_setcb(buf, NULL, NULL);
82
83		if (bufev->enabled & EV_READ)
84			bufferevent_add(&bufev->ev_read, bufev->timeout_read);
85	}
86}
87
88static void
89bufferevent_readcb(int fd, short event, void *arg)
90{
91	struct bufferevent *bufev = arg;
92	int res = 0;
93	short what = EVBUFFER_READ;
94	size_t len;
95	int howmuch = -1;
96
97	if (event == EV_TIMEOUT) {
98		what |= EVBUFFER_TIMEOUT;
99		goto error;
100	}
101
102	/*
103	 * If we have a high watermark configured then we don't want to
104	 * read more data than would make us reach the watermark.
105	 */
106	if (bufev->wm_read.high != 0)
107		howmuch = bufev->wm_read.high;
108
109	res = evbuffer_read(bufev->input, fd, howmuch);
110	if (res == -1) {
111		if (errno == EAGAIN || errno == EINTR)
112			goto reschedule;
113		/* error case */
114		what |= EVBUFFER_ERROR;
115	} else if (res == 0) {
116		/* eof case */
117		what |= EVBUFFER_EOF;
118	}
119
120	if (res <= 0)
121		goto error;
122
123	bufferevent_add(&bufev->ev_read, bufev->timeout_read);
124
125	/* See if this callbacks meets the water marks */
126	len = EVBUFFER_LENGTH(bufev->input);
127	if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
128		return;
129	if (bufev->wm_read.high != 0 && len > bufev->wm_read.high) {
130		struct evbuffer *buf = bufev->input;
131		event_del(&bufev->ev_read);
132
133		/* Now schedule a callback for us */
134		evbuffer_setcb(buf, bufferevent_read_pressure_cb, bufev);
135		return;
136	}
137
138	/* Invoke the user callback - must always be called last */
139	if (bufev->readcb != NULL)
140		(*bufev->readcb)(bufev, bufev->cbarg);
141	return;
142
143 reschedule:
144	bufferevent_add(&bufev->ev_read, bufev->timeout_read);
145	return;
146
147 error:
148	(*bufev->errorcb)(bufev, what, bufev->cbarg);
149}
150
151static void
152bufferevent_writecb(int fd, short event, void *arg)
153{
154	struct bufferevent *bufev = arg;
155	int res = 0;
156	short what = EVBUFFER_WRITE;
157
158	if (event == EV_TIMEOUT) {
159		what |= EVBUFFER_TIMEOUT;
160		goto error;
161	}
162
163	if (EVBUFFER_LENGTH(bufev->output)) {
164	    res = evbuffer_write(bufev->output, fd);
165	    if (res == -1) {
166#ifndef WIN32
167/*todo. evbuffer uses WriteFile when WIN32 is set. WIN32 system calls do not
168 *set errno. thus this error checking is not portable*/
169		    if (errno == EAGAIN ||
170			errno == EINTR ||
171			errno == EINPROGRESS)
172			    goto reschedule;
173		    /* error case */
174		    what |= EVBUFFER_ERROR;
175
176#else
177				goto reschedule;
178#endif
179
180	    } else if (res == 0) {
181		    /* eof case */
182		    what |= EVBUFFER_EOF;
183	    }
184	    if (res <= 0)
185		    goto error;
186	}
187
188	if (EVBUFFER_LENGTH(bufev->output) != 0)
189		bufferevent_add(&bufev->ev_write, bufev->timeout_write);
190
191	/*
192	 * Invoke the user callback if our buffer is drained or below the
193	 * low watermark.
194	 */
195	if (bufev->writecb != NULL &&
196	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
197		(*bufev->writecb)(bufev, bufev->cbarg);
198
199	return;
200
201 reschedule:
202	if (EVBUFFER_LENGTH(bufev->output) != 0)
203		bufferevent_add(&bufev->ev_write, bufev->timeout_write);
204	return;
205
206 error:
207	(*bufev->errorcb)(bufev, what, bufev->cbarg);
208}
209
210/*
211 * Create a new buffered event object.
212 *
213 * The read callback is invoked whenever we read new data.
214 * The write callback is invoked whenever the output buffer is drained.
215 * The error callback is invoked on a write/read error or on EOF.
216 *
217 * Both read and write callbacks maybe NULL.  The error callback is not
218 * allowed to be NULL and have to be provided always.
219 */
220
221struct bufferevent *
222bufferevent_new(int fd, evbuffercb readcb, evbuffercb writecb,
223    everrorcb errorcb, void *cbarg)
224{
225	struct bufferevent *bufev;
226
227	if ((bufev = calloc(1, sizeof(struct bufferevent))) == NULL)
228		return (NULL);
229
230	if ((bufev->input = evbuffer_new()) == NULL) {
231		free(bufev);
232		return (NULL);
233	}
234
235	if ((bufev->output = evbuffer_new()) == NULL) {
236		evbuffer_free(bufev->input);
237		free(bufev);
238		return (NULL);
239	}
240
241	event_set(&bufev->ev_read, fd, EV_READ, bufferevent_readcb, bufev);
242	event_set(&bufev->ev_write, fd, EV_WRITE, bufferevent_writecb, bufev);
243
244	bufev->readcb = readcb;
245	bufev->writecb = writecb;
246	bufev->errorcb = errorcb;
247
248	bufev->cbarg = cbarg;
249
250	/*
251	 * Set to EV_WRITE so that using bufferevent_write is going to
252	 * trigger a callback.  Reading needs to be explicitly enabled
253	 * because otherwise no data will be available.
254	 */
255	bufev->enabled = EV_WRITE;
256
257	return (bufev);
258}
259
260int
261bufferevent_priority_set(struct bufferevent *bufev, int priority)
262{
263	if (event_priority_set(&bufev->ev_read, priority) == -1)
264		return (-1);
265	if (event_priority_set(&bufev->ev_write, priority) == -1)
266		return (-1);
267
268	return (0);
269}
270
271/* Closing the file descriptor is the responsibility of the caller */
272
273void
274bufferevent_free(struct bufferevent *bufev)
275{
276	event_del(&bufev->ev_read);
277	event_del(&bufev->ev_write);
278
279	evbuffer_free(bufev->input);
280	evbuffer_free(bufev->output);
281
282	free(bufev);
283}
284
285/*
286 * Returns 0 on success;
287 *        -1 on failure.
288 */
289
290int
291bufferevent_write(struct bufferevent *bufev, void *data, size_t size)
292{
293	int res;
294
295	res = evbuffer_add(bufev->output, data, size);
296
297	if (res == -1)
298		return (res);
299
300	/* If everything is okay, we need to schedule a write */
301	if (size > 0 && (bufev->enabled & EV_WRITE))
302		bufferevent_add(&bufev->ev_write, bufev->timeout_write);
303
304	return (res);
305}
306
307int
308bufferevent_write_buffer(struct bufferevent *bufev, struct evbuffer *buf)
309{
310	int res;
311
312	res = bufferevent_write(bufev, buf->buffer, buf->off);
313	if (res != -1)
314		evbuffer_drain(buf, buf->off);
315
316	return (res);
317}
318
319size_t
320bufferevent_read(struct bufferevent *bufev, void *data, size_t size)
321{
322	struct evbuffer *buf = bufev->input;
323
324	if (buf->off < size)
325		size = buf->off;
326
327	/* Copy the available data to the user buffer */
328	memcpy(data, buf->buffer, size);
329
330	if (size)
331		evbuffer_drain(buf, size);
332
333	return (size);
334}
335
336int
337bufferevent_enable(struct bufferevent *bufev, short event)
338{
339	if (event & EV_READ) {
340		if (bufferevent_add(&bufev->ev_read, bufev->timeout_read) == -1)
341			return (-1);
342	}
343	if (event & EV_WRITE) {
344		if (bufferevent_add(&bufev->ev_write, bufev->timeout_write) == -1)
345			return (-1);
346	}
347
348	bufev->enabled |= event;
349	return (0);
350}
351
352int
353bufferevent_disable(struct bufferevent *bufev, short event)
354{
355	if (event & EV_READ) {
356		if (event_del(&bufev->ev_read) == -1)
357			return (-1);
358	}
359	if (event & EV_WRITE) {
360		if (event_del(&bufev->ev_write) == -1)
361			return (-1);
362	}
363
364	bufev->enabled &= ~event;
365	return (0);
366}
367
368/*
369 * Sets the read and write timeout for a buffered event.
370 */
371
372void
373bufferevent_settimeout(struct bufferevent *bufev,
374    int timeout_read, int timeout_write) {
375	bufev->timeout_read = timeout_read;
376	bufev->timeout_write = timeout_write;
377}
378
379/*
380 * Sets the water marks
381 */
382
383void
384bufferevent_setwatermark(struct bufferevent *bufev, short events,
385    size_t lowmark, size_t highmark)
386{
387	if (events & EV_READ) {
388		bufev->wm_read.low = lowmark;
389		bufev->wm_read.high = highmark;
390	}
391
392	if (events & EV_WRITE) {
393		bufev->wm_write.low = lowmark;
394		bufev->wm_write.high = highmark;
395	}
396
397	/* If the watermarks changed then see if we should call read again */
398	bufferevent_read_pressure_cb(bufev->input,
399	    0, EVBUFFER_LENGTH(bufev->input), bufev);
400}
401
402int
403bufferevent_base_set(struct event_base *base, struct bufferevent *bufev)
404{
405	int res;
406
407	res = event_base_set(base, &bufev->ev_read);
408	if (res == -1)
409		return (res);
410
411	res = event_base_set(base, &bufev->ev_write);
412	return (res);
413}
414