xref: /openbsd-src/lib/libevent/buffer.c (revision cd1eb269cafb12c415be1749cd4a4b5422710415) 
1 /*	$OpenBSD: buffer.c,v 1.17 2010/04/21 20:02:40 nicm Exp $	*/
2 
3 /*
4  * Copyright (c) 2002, 2003 Niels Provos <provos@citi.umich.edu>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. The name of the author may not be used to endorse or promote products
16  *    derived from this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #ifdef HAVE_CONFIG_H
31 #include "config.h"
32 #endif
33 
34 #ifdef WIN32
35 #include <winsock2.h>
36 #include <windows.h>
37 #endif
38 
39 #ifdef HAVE_VASPRINTF
40 /* If we have vasprintf, we need to define this before we include stdio.h. */
41 #define _GNU_SOURCE
42 #endif
43 
44 #include <sys/types.h>
45 
46 #ifdef HAVE_SYS_TIME_H
47 #include <sys/time.h>
48 #endif
49 
50 #ifdef HAVE_SYS_IOCTL_H
51 #include <sys/ioctl.h>
52 #endif
53 
54 #include <assert.h>
55 #include <errno.h>
56 #include <stdio.h>
57 #include <stdlib.h>
58 #include <string.h>
59 #ifdef HAVE_STDARG_H
60 #include <stdarg.h>
61 #endif
62 #ifdef HAVE_UNISTD_H
63 #include <unistd.h>
64 #endif
65 
66 #include "event.h"
67 #include "evutil.h"
68 
69 struct evbuffer *
70 evbuffer_new(void)
71 {
72 	struct evbuffer *buffer;
73 
74 	buffer = calloc(1, sizeof(struct evbuffer));
75 
76 	return (buffer);
77 }
78 
79 void
80 evbuffer_free(struct evbuffer *buffer)
81 {
82 	if (buffer->orig_buffer != NULL)
83 		free(buffer->orig_buffer);
84 	free(buffer);
85 }
86 
87 /*
88  * This is a destructive add.  The data from one buffer moves into
89  * the other buffer.
90  */
91 
92 #define SWAP(x,y) do { \
93 	(x)->buffer = (y)->buffer; \
94 	(x)->orig_buffer = (y)->orig_buffer; \
95 	(x)->misalign = (y)->misalign; \
96 	(x)->totallen = (y)->totallen; \
97 	(x)->off = (y)->off; \
98 } while (0)
99 
100 int
101 evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
102 {
103 	int res;
104 
105 	/* Short cut for better performance */
106 	if (outbuf->off == 0) {
107 		struct evbuffer tmp;
108 		size_t oldoff = inbuf->off;
109 
110 		/* Swap them directly */
111 		SWAP(&tmp, outbuf);
112 		SWAP(outbuf, inbuf);
113 		SWAP(inbuf, &tmp);
114 
115 		/*
116 		 * Optimization comes with a price; we need to notify the
117 		 * buffer if necessary of the changes. oldoff is the amount
118 		 * of data that we transferred from inbuf to outbuf
119 		 */
120 		if (inbuf->off != oldoff && inbuf->cb != NULL)
121 			(*inbuf->cb)(inbuf, oldoff, inbuf->off, inbuf->cbarg);
122 		if (oldoff && outbuf->cb != NULL)
123 			(*outbuf->cb)(outbuf, 0, oldoff, outbuf->cbarg);
124 
125 		return (0);
126 	}
127 
128 	res = evbuffer_add(outbuf, inbuf->buffer, inbuf->off);
129 	if (res == 0) {
130 		/* We drain the input buffer on success */
131 		evbuffer_drain(inbuf, inbuf->off);
132 	}
133 
134 	return (res);
135 }
136 
137 int
138 evbuffer_add_vprintf(struct evbuffer *buf, const char *fmt, va_list ap)
139 {
140 	char *buffer;
141 	size_t space;
142 	size_t oldoff = buf->off;
143 	int sz;
144 	va_list aq;
145 
146 	/* make sure that at least some space is available */
147 	evbuffer_expand(buf, 64);
148 	for (;;) {
149 		size_t used = buf->misalign + buf->off;
150 		buffer = (char *)buf->buffer + buf->off;
151 		assert(buf->totallen >= used);
152 		space = buf->totallen - used;
153 
154 #ifndef va_copy
155 #define	va_copy(dst, src)	memcpy(&(dst), &(src), sizeof(va_list))
156 #endif
157 		va_copy(aq, ap);
158 
159 		sz = evutil_vsnprintf(buffer, space, fmt, aq);
160 
161 		va_end(aq);
162 
163 		if (sz < 0)
164 			return (-1);
165 		if ((size_t)sz < space) {
166 			buf->off += sz;
167 			if (buf->cb != NULL)
168 				(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
169 			return (sz);
170 		}
171 		if (evbuffer_expand(buf, sz + 1) == -1)
172 			return (-1);
173 
174 	}
175 	/* NOTREACHED */
176 }
177 
178 int
179 evbuffer_add_printf(struct evbuffer *buf, const char *fmt, ...)
180 {
181 	int res = -1;
182 	va_list ap;
183 
184 	va_start(ap, fmt);
185 	res = evbuffer_add_vprintf(buf, fmt, ap);
186 	va_end(ap);
187 
188 	return (res);
189 }
190 
191 /* Reads data from an event buffer and drains the bytes read */
192 
193 int
194 evbuffer_remove(struct evbuffer *buf, void *data, size_t datlen)
195 {
196 	size_t nread = datlen;
197 	if (nread >= buf->off)
198 		nread = buf->off;
199 
200 	memcpy(data, buf->buffer, nread);
201 	evbuffer_drain(buf, nread);
202 
203 	return (nread);
204 }
205 
206 /*
207  * Reads a line terminated by either '\r\n', '\n\r' or '\r' or '\n'.
208  * The returned buffer needs to be freed by the called.
209  */
210 
211 char *
212 evbuffer_readline(struct evbuffer *buffer)
213 {
214 	u_char *data = EVBUFFER_DATA(buffer);
215 	size_t len = EVBUFFER_LENGTH(buffer);
216 	char *line;
217 	unsigned int i;
218 
219 	for (i = 0; i < len; i++) {
220 		if (data[i] == '\r' || data[i] == '\n')
221 			break;
222 	}
223 
224 	if (i == len)
225 		return (NULL);
226 
227 	if ((line = malloc(i + 1)) == NULL) {
228 		fprintf(stderr, "%s: out of memory\n", __func__);
229 		return (NULL);
230 	}
231 
232 	memcpy(line, data, i);
233 	line[i] = '\0';
234 
235 	/*
236 	 * Some protocols terminate a line with '\r\n', so check for
237 	 * that, too.
238 	 */
239 	if ( i < len - 1 ) {
240 		char fch = data[i], sch = data[i+1];
241 
242 		/* Drain one more character if needed */
243 		if ( (sch == '\r' || sch == '\n') && sch != fch )
244 			i += 1;
245 	}
246 
247 	evbuffer_drain(buffer, i + 1);
248 
249 	return (line);
250 }
251 
252 
253 char *
254 evbuffer_readln(struct evbuffer *buffer, size_t *n_read_out,
255 		enum evbuffer_eol_style eol_style)
256 {
257 	u_char *data = EVBUFFER_DATA(buffer);
258 	u_char *start_of_eol, *end_of_eol;
259 	size_t len = EVBUFFER_LENGTH(buffer);
260 	char *line;
261 	unsigned int i, n_to_copy, n_to_drain;
262 
263 	/* depending on eol_style, set start_of_eol to the first character
264 	 * in the newline, and end_of_eol to one after the last character. */
265 	switch (eol_style) {
266 	case EVBUFFER_EOL_ANY:
267 		for (i = 0; i < len; i++) {
268 			if (data[i] == '\r' || data[i] == '\n')
269 				break;
270 		}
271 		if (i == len)
272 			return (NULL);
273 		start_of_eol = data+i;
274 		++i;
275 		for ( ; i < len; i++) {
276 			if (data[i] != '\r' && data[i] != '\n')
277 				break;
278 		}
279 		end_of_eol = data+i;
280 		break;
281 	case EVBUFFER_EOL_CRLF:
282 		end_of_eol = memchr(data, '\n', len);
283 		if (!end_of_eol)
284 			return (NULL);
285 		if (end_of_eol > data && *(end_of_eol-1) == '\r')
286 			start_of_eol = end_of_eol - 1;
287 		else
288 			start_of_eol = end_of_eol;
289 		end_of_eol++; /*point to one after the LF. */
290 		break;
291 	case EVBUFFER_EOL_CRLF_STRICT: {
292 		u_char *cp = data;
293 		while ((cp = memchr(cp, '\r', len-(cp-data)))) {
294 			if (cp < data+len-1 && *(cp+1) == '\n')
295 				break;
296 			if (++cp >= data+len) {
297 				cp = NULL;
298 				break;
299 			}
300 		}
301 		if (!cp)
302 			return (NULL);
303 		start_of_eol = cp;
304 		end_of_eol = cp+2;
305 		break;
306 	}
307 	case EVBUFFER_EOL_LF:
308 		start_of_eol = memchr(data, '\n', len);
309 		if (!start_of_eol)
310 			return (NULL);
311 		end_of_eol = start_of_eol + 1;
312 		break;
313 	default:
314 		return (NULL);
315 	}
316 
317 	n_to_copy = start_of_eol - data;
318 	n_to_drain = end_of_eol - data;
319 
320 	if ((line = malloc(n_to_copy+1)) == NULL) {
321 		fprintf(stderr, "%s: out of memory\n", __func__);
322 		evbuffer_drain(buffer, n_to_drain);
323 		return (NULL);
324 	}
325 
326 	memcpy(line, data, n_to_copy);
327 	line[n_to_copy] = '\0';
328 
329 	evbuffer_drain(buffer, n_to_drain);
330 	if (n_read_out)
331 		*n_read_out = (size_t)n_to_copy;
332 
333 	return (line);
334 }
335 
336 /* Adds data to an event buffer */
337 
338 static void
339 evbuffer_align(struct evbuffer *buf)
340 {
341 	memmove(buf->orig_buffer, buf->buffer, buf->off);
342 	buf->buffer = buf->orig_buffer;
343 	buf->misalign = 0;
344 }
345 
346 /* Expands the available space in the event buffer to at least datlen */
347 
348 int
349 evbuffer_expand(struct evbuffer *buf, size_t datlen)
350 {
351 	size_t need = buf->misalign + buf->off + datlen;
352 
353 	/* If we can fit all the data, then we don't have to do anything */
354 	if (buf->totallen >= need)
355 		return (0);
356 
357 	/*
358 	 * If the misalignment fulfills our data needs, we just force an
359 	 * alignment to happen.  Afterwards, we have enough space.
360 	 */
361 	if (buf->misalign >= datlen) {
362 		evbuffer_align(buf);
363 	} else {
364 		void *newbuf;
365 		size_t length = buf->totallen;
366 
367 		if (length < 256)
368 			length = 256;
369 		while (length < need)
370 			length <<= 1;
371 
372 		if (buf->orig_buffer != buf->buffer)
373 			evbuffer_align(buf);
374 		if ((newbuf = realloc(buf->buffer, length)) == NULL)
375 			return (-1);
376 
377 		buf->orig_buffer = buf->buffer = newbuf;
378 		buf->totallen = length;
379 	}
380 
381 	return (0);
382 }
383 
384 int
385 evbuffer_add(struct evbuffer *buf, const void *data, size_t datlen)
386 {
387 	size_t need = buf->misalign + buf->off + datlen;
388 	size_t oldoff = buf->off;
389 
390 	if (buf->totallen < need) {
391 		if (evbuffer_expand(buf, datlen) == -1)
392 			return (-1);
393 	}
394 
395 	memcpy(buf->buffer + buf->off, data, datlen);
396 	buf->off += datlen;
397 
398 	if (datlen && buf->cb != NULL)
399 		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
400 
401 	return (0);
402 }
403 
404 void
405 evbuffer_drain(struct evbuffer *buf, size_t len)
406 {
407 	size_t oldoff = buf->off;
408 
409 	if (len >= buf->off) {
410 		buf->off = 0;
411 		buf->buffer = buf->orig_buffer;
412 		buf->misalign = 0;
413 		goto done;
414 	}
415 
416 	buf->buffer += len;
417 	buf->misalign += len;
418 
419 	buf->off -= len;
420 
421  done:
422 	/* Tell someone about changes in this buffer */
423 	if (buf->off != oldoff && buf->cb != NULL)
424 		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
425 
426 }
427 
428 /*
429  * Reads data from a file descriptor into a buffer.
430  */
431 
432 #define EVBUFFER_MAX_READ	4096
433 
434 int
435 evbuffer_read(struct evbuffer *buf, int fd, int howmuch)
436 {
437 	u_char *p;
438 	size_t oldoff = buf->off;
439 	int n = EVBUFFER_MAX_READ;
440 
441 #if defined(FIONREAD)
442 #ifdef WIN32
443 	long lng = n;
444 	if (ioctlsocket(fd, FIONREAD, &lng) == -1 || (n=lng) <= 0) {
445 #else
446 	if (ioctl(fd, FIONREAD, &n) == -1 || n <= 0) {
447 #endif
448 		n = EVBUFFER_MAX_READ;
449 	} else if (n > EVBUFFER_MAX_READ && n > howmuch) {
450 		/*
451 		 * It's possible that a lot of data is available for
452 		 * reading.  We do not want to exhaust resources
453 		 * before the reader has a chance to do something
454 		 * about it.  If the reader does not tell us how much
455 		 * data we should read, we artifically limit it.
456 		 */
457 		if ((size_t)n > buf->totallen << 2)
458 			n = buf->totallen << 2;
459 		if (n < EVBUFFER_MAX_READ)
460 			n = EVBUFFER_MAX_READ;
461 	}
462 #endif
463 	if (howmuch < 0 || howmuch > n)
464 		howmuch = n;
465 
466 	/* If we don't have FIONREAD, we might waste some space here */
467 	if (evbuffer_expand(buf, howmuch) == -1)
468 		return (-1);
469 
470 	/* We can append new data at this point */
471 	p = buf->buffer + buf->off;
472 
473 #ifndef WIN32
474 	n = read(fd, p, howmuch);
475 #else
476 	n = recv(fd, p, howmuch, 0);
477 #endif
478 	if (n == -1)
479 		return (-1);
480 	if (n == 0)
481 		return (0);
482 
483 	buf->off += n;
484 
485 	/* Tell someone about changes in this buffer */
486 	if (buf->off != oldoff && buf->cb != NULL)
487 		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
488 
489 	return (n);
490 }
491 
492 int
493 evbuffer_write(struct evbuffer *buffer, int fd)
494 {
495 	int n;
496 
497 #ifndef WIN32
498 	n = write(fd, buffer->buffer, buffer->off);
499 #else
500 	n = send(fd, buffer->buffer, buffer->off, 0);
501 #endif
502 	if (n == -1)
503 		return (-1);
504 	if (n == 0)
505 		return (0);
506 	evbuffer_drain(buffer, n);
507 
508 	return (n);
509 }
510 
511 u_char *
512 evbuffer_find(struct evbuffer *buffer, const u_char *what, size_t len)
513 {
514 	u_char *search = buffer->buffer, *end = search + buffer->off;
515 	u_char *p;
516 
517 	while (search < end &&
518 	    (p = memchr(search, *what, end - search)) != NULL) {
519 		if (p + len > end)
520 			break;
521 		if (memcmp(p, what, len) == 0)
522 			return (p);
523 		search = p + 1;
524 	}
525 
526 	return (NULL);
527 }
528 
529 void evbuffer_setcb(struct evbuffer *buffer,
530     void (*cb)(struct evbuffer *, size_t, size_t, void *),
531     void *cbarg)
532 {
533 	buffer->cb = cb;
534 	buffer->cbarg = cbarg;
535 }
536