1/*	$OpenBSD: buffer.c,v 1.33 2022/12/27 23:05:55 jmc 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#include <sys/types.h>
31#include <sys/time.h>
32#include <sys/ioctl.h>
33
34#include <assert.h>
35#include <errno.h>
36#include <stdint.h>
37#include <stdio.h>
38#include <stdlib.h>
39#include <string.h>
40#include <stdarg.h>
41#include <unistd.h>
42
43#include "event.h"
44#include "log.h"
45
46struct evbuffer *
47evbuffer_new(void)
48{
49	struct evbuffer *buffer;
50
51	buffer = calloc(1, sizeof(struct evbuffer));
52
53	return (buffer);
54}
55
56void
57evbuffer_free(struct evbuffer *buffer)
58{
59	free(buffer->orig_buffer);
60	free(buffer);
61}
62
63/*
64 * This is a destructive add.  The data from one buffer moves into
65 * the other buffer.
66 */
67
68#define SWAP(x,y) do { \
69	(x)->buffer = (y)->buffer; \
70	(x)->orig_buffer = (y)->orig_buffer; \
71	(x)->misalign = (y)->misalign; \
72	(x)->totallen = (y)->totallen; \
73	(x)->off = (y)->off; \
74} while (0)
75
76int
77evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
78{
79	int res;
80
81	/* Short cut for better performance */
82	if (outbuf->off == 0) {
83		struct evbuffer tmp;
84		size_t oldoff = inbuf->off;
85
86		/* Swap them directly */
87		SWAP(&tmp, outbuf);
88		SWAP(outbuf, inbuf);
89		SWAP(inbuf, &tmp);
90
91		/*
92		 * Optimization comes with a price; we need to notify the
93		 * buffer if necessary of the changes. oldoff is the amount
94		 * of data that we transferred from inbuf to outbuf
95		 */
96		if (inbuf->off != oldoff && inbuf->cb != NULL)
97			(*inbuf->cb)(inbuf, oldoff, inbuf->off, inbuf->cbarg);
98		if (oldoff && outbuf->cb != NULL)
99			(*outbuf->cb)(outbuf, 0, oldoff, outbuf->cbarg);
100
101		return (0);
102	}
103
104	res = evbuffer_add(outbuf, inbuf->buffer, inbuf->off);
105	if (res == 0) {
106		/* We drain the input buffer on success */
107		evbuffer_drain(inbuf, inbuf->off);
108	}
109
110	return (res);
111}
112
113int
114evbuffer_add_vprintf(struct evbuffer *buf, const char *fmt, va_list ap)
115{
116	char *buffer;
117	size_t space;
118	size_t oldoff = buf->off;
119	int sz;
120	va_list aq;
121
122	/* make sure that at least some space is available */
123	if (evbuffer_expand(buf, 64) < 0)
124		return (-1);
125	for (;;) {
126		size_t used = buf->misalign + buf->off;
127		buffer = (char *)buf->buffer + buf->off;
128		assert(buf->totallen >= used);
129		space = buf->totallen - used;
130
131		va_copy(aq, ap);
132
133		sz = vsnprintf(buffer, space, fmt, aq);
134
135		va_end(aq);
136
137		if (sz < 0)
138			return (-1);
139		if ((size_t)sz < space) {
140			buf->off += sz;
141			if (buf->cb != NULL)
142				(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
143			return (sz);
144		}
145		if (evbuffer_expand(buf, sz + 1) == -1)
146			return (-1);
147
148	}
149	/* NOTREACHED */
150}
151
152int
153evbuffer_add_printf(struct evbuffer *buf, const char *fmt, ...)
154{
155	int res = -1;
156	va_list ap;
157
158	va_start(ap, fmt);
159	res = evbuffer_add_vprintf(buf, fmt, ap);
160	va_end(ap);
161
162	return (res);
163}
164
165/* Reads data from an event buffer and drains the bytes read */
166
167int
168evbuffer_remove(struct evbuffer *buf, void *data, size_t datlen)
169{
170	size_t nread = datlen;
171	if (nread >= buf->off)
172		nread = buf->off;
173
174	memcpy(data, buf->buffer, nread);
175	evbuffer_drain(buf, nread);
176
177	return (nread);
178}
179
180/*
181 * Reads a line terminated by either '\r\n', '\n\r' or '\r' or '\n'.
182 * The returned buffer needs to be freed by the called.
183 */
184
185char *
186evbuffer_readline(struct evbuffer *buffer)
187{
188	u_char *data = EVBUFFER_DATA(buffer);
189	size_t len = EVBUFFER_LENGTH(buffer);
190	char *line;
191	size_t i;
192
193	for (i = 0; i < len; i++) {
194		if (data[i] == '\r' || data[i] == '\n')
195			break;
196	}
197
198	if (i == len)
199		return (NULL);
200
201	if ((line = malloc(i + 1)) == NULL) {
202		event_warn("%s: out of memory", __func__);
203		return (NULL);
204	}
205
206	memcpy(line, data, i);
207	line[i] = '\0';
208
209	/*
210	 * Some protocols terminate a line with '\r\n', so check for
211	 * that, too.
212	 */
213	if ( i < len - 1 ) {
214		char fch = data[i], sch = data[i+1];
215
216		/* Drain one more character if needed */
217		if ( (sch == '\r' || sch == '\n') && sch != fch )
218			i += 1;
219	}
220
221	evbuffer_drain(buffer, i + 1);
222
223	return (line);
224}
225
226
227char *
228evbuffer_readln(struct evbuffer *buffer, size_t *n_read_out,
229		enum evbuffer_eol_style eol_style)
230{
231	u_char *data = EVBUFFER_DATA(buffer);
232	u_char *start_of_eol, *end_of_eol;
233	size_t len = EVBUFFER_LENGTH(buffer);
234	char *line;
235	size_t i, n_to_copy, n_to_drain;
236
237	if (n_read_out)
238		*n_read_out = 0;
239
240	/* depending on eol_style, set start_of_eol to the first character
241	 * in the newline, and end_of_eol to one after the last character. */
242	switch (eol_style) {
243	case EVBUFFER_EOL_ANY:
244		for (i = 0; i < len; i++) {
245			if (data[i] == '\r' || data[i] == '\n')
246				break;
247		}
248		if (i == len)
249			return (NULL);
250		start_of_eol = data+i;
251		++i;
252		for ( ; i < len; i++) {
253			if (data[i] != '\r' && data[i] != '\n')
254				break;
255		}
256		end_of_eol = data+i;
257		break;
258	case EVBUFFER_EOL_CRLF:
259		end_of_eol = memchr(data, '\n', len);
260		if (!end_of_eol)
261			return (NULL);
262		if (end_of_eol > data && *(end_of_eol-1) == '\r')
263			start_of_eol = end_of_eol - 1;
264		else
265			start_of_eol = end_of_eol;
266		end_of_eol++; /*point to one after the LF. */
267		break;
268	case EVBUFFER_EOL_CRLF_STRICT: {
269		u_char *cp = data;
270		while ((cp = memchr(cp, '\r', len-(cp-data)))) {
271			if (cp < data+len-1 && *(cp+1) == '\n')
272				break;
273			if (++cp >= data+len) {
274				cp = NULL;
275				break;
276			}
277		}
278		if (!cp)
279			return (NULL);
280		start_of_eol = cp;
281		end_of_eol = cp+2;
282		break;
283	}
284	case EVBUFFER_EOL_LF:
285		start_of_eol = memchr(data, '\n', len);
286		if (!start_of_eol)
287			return (NULL);
288		end_of_eol = start_of_eol + 1;
289		break;
290	default:
291		return (NULL);
292	}
293
294	n_to_copy = start_of_eol - data;
295	n_to_drain = end_of_eol - data;
296
297	if ((line = malloc(n_to_copy+1)) == NULL) {
298		event_warn("%s: out of memory", __func__);
299		return (NULL);
300	}
301
302	memcpy(line, data, n_to_copy);
303	line[n_to_copy] = '\0';
304
305	evbuffer_drain(buffer, n_to_drain);
306	if (n_read_out)
307		*n_read_out = (size_t)n_to_copy;
308
309	return (line);
310}
311
312/* Adds data to an event buffer */
313
314static void
315evbuffer_align(struct evbuffer *buf)
316{
317	memmove(buf->orig_buffer, buf->buffer, buf->off);
318	buf->buffer = buf->orig_buffer;
319	buf->misalign = 0;
320}
321
322/* Expands the available space in the event buffer to at least datlen */
323
324int
325evbuffer_expand(struct evbuffer *buf, size_t datlen)
326{
327	size_t used = buf->misalign + buf->off;
328
329	assert(buf->totallen >= used);
330
331	/* If we can fit all the data, then we don't have to do anything */
332	if (buf->totallen - used >= datlen)
333		return (0);
334	/* If we would need to overflow to fit this much data, we can't
335	 * do anything. */
336	if (datlen > SIZE_MAX - buf->off)
337		return (-1);
338
339	/*
340	 * If the misalignment fulfills our data needs, we just force an
341	 * alignment to happen.  Afterwards, we have enough space.
342	 */
343	if (buf->totallen - buf->off >= datlen) {
344		evbuffer_align(buf);
345	} else {
346		void *newbuf;
347		size_t length = buf->totallen;
348		size_t need = buf->off + datlen;
349
350		if (length < 256)
351			length = 256;
352		if (need < SIZE_MAX / 2) {
353			while (length < need) {
354				length <<= 1;
355			}
356		} else {
357			length = need;
358		}
359
360		if (buf->orig_buffer != buf->buffer)
361			evbuffer_align(buf);
362		if ((newbuf = recallocarray(buf->buffer, buf->totallen,
363		    length, 1)) == NULL)
364			return (-1);
365
366		buf->orig_buffer = buf->buffer = newbuf;
367		buf->totallen = length;
368	}
369
370	return (0);
371}
372
373int
374evbuffer_add(struct evbuffer *buf, const void *data, size_t datlen)
375{
376	size_t used = buf->misalign + buf->off;
377	size_t oldoff = buf->off;
378
379	if (buf->totallen - used < datlen) {
380		if (evbuffer_expand(buf, datlen) == -1)
381			return (-1);
382	}
383
384	memcpy(buf->buffer + buf->off, data, datlen);
385	buf->off += datlen;
386
387	if (datlen && buf->cb != NULL)
388		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
389
390	return (0);
391}
392
393void
394evbuffer_drain(struct evbuffer *buf, size_t len)
395{
396	size_t oldoff = buf->off;
397
398	if (len >= buf->off) {
399		buf->off = 0;
400		buf->buffer = buf->orig_buffer;
401		buf->misalign = 0;
402		goto done;
403	}
404
405	buf->buffer += len;
406	buf->misalign += len;
407
408	buf->off -= len;
409
410 done:
411	/* Tell someone about changes in this buffer */
412	if (buf->off != oldoff && buf->cb != NULL)
413		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
414
415}
416
417/*
418 * Reads data from a file descriptor into a buffer.
419 */
420
421#define EVBUFFER_MAX_READ	4096
422
423int
424evbuffer_read(struct evbuffer *buf, int fd, int howmuch)
425{
426	u_char *p;
427	size_t oldoff = buf->off;
428	int n = EVBUFFER_MAX_READ;
429
430	if (ioctl(fd, FIONREAD, &n) == -1 || n <= 0) {
431		n = EVBUFFER_MAX_READ;
432	} else if (n > EVBUFFER_MAX_READ && n > howmuch) {
433		/*
434		 * It's possible that a lot of data is available for
435		 * reading.  We do not want to exhaust resources
436		 * before the reader has a chance to do something
437		 * about it.  If the reader does not tell us how much
438		 * data we should read, we artificially limit it.
439		 */
440		if ((size_t)n > buf->totallen << 2)
441			n = buf->totallen << 2;
442		if (n < EVBUFFER_MAX_READ)
443			n = EVBUFFER_MAX_READ;
444	}
445	if (howmuch < 0 || howmuch > n)
446		howmuch = n;
447
448	/* If we don't have FIONREAD, we might waste some space here */
449	if (evbuffer_expand(buf, howmuch) == -1)
450		return (-1);
451
452	/* We can append new data at this point */
453	p = buf->buffer + buf->off;
454
455	n = read(fd, p, howmuch);
456	if (n == -1)
457		return (-1);
458	if (n == 0)
459		return (0);
460
461	buf->off += n;
462
463	/* Tell someone about changes in this buffer */
464	if (buf->off != oldoff && buf->cb != NULL)
465		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
466
467	return (n);
468}
469
470int
471evbuffer_write(struct evbuffer *buffer, int fd)
472{
473	int n;
474
475	n = write(fd, buffer->buffer, buffer->off);
476	if (n == -1)
477		return (-1);
478	if (n == 0)
479		return (0);
480	evbuffer_drain(buffer, n);
481
482	return (n);
483}
484
485u_char *
486evbuffer_find(struct evbuffer *buffer, const u_char *what, size_t len)
487{
488	u_char *search = buffer->buffer, *end = search + buffer->off;
489	u_char *p;
490
491	while (search < end &&
492	    (p = memchr(search, *what, end - search)) != NULL) {
493		if (p + len > end)
494			break;
495		if (memcmp(p, what, len) == 0)
496			return (p);
497		search = p + 1;
498	}
499
500	return (NULL);
501}
502
503void evbuffer_setcb(struct evbuffer *buffer,
504    void (*cb)(struct evbuffer *, size_t, size_t, void *),
505    void *cbarg)
506{
507	buffer->cb = cb;
508	buffer->cbarg = cbarg;
509}
510