buffer.c revision 146998 
1/*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 *                    All rights reserved
5 * Functions for manipulating fifo buffers (that can grow if needed).
6 *
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose.  Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 */
13
14#include "includes.h"
15RCSID("$OpenBSD: buffer.c,v 1.22 2004/10/29 23:56:17 djm Exp $");
16
17#include "xmalloc.h"
18#include "buffer.h"
19#include "log.h"
20
21/* Initializes the buffer structure. */
22
23void
24buffer_init(Buffer *buffer)
25{
26	const u_int len = 4096;
27
28	buffer->alloc = 0;
29	buffer->buf = xmalloc(len);
30	buffer->alloc = len;
31	buffer->offset = 0;
32	buffer->end = 0;
33}
34
35/* Frees any memory used for the buffer. */
36
37void
38buffer_free(Buffer *buffer)
39{
40	if (buffer->alloc > 0) {
41		memset(buffer->buf, 0, buffer->alloc);
42		buffer->alloc = 0;
43		xfree(buffer->buf);
44	}
45}
46
47/*
48 * Clears any data from the buffer, making it empty.  This does not actually
49 * zero the memory.
50 */
51
52void
53buffer_clear(Buffer *buffer)
54{
55	buffer->offset = 0;
56	buffer->end = 0;
57}
58
59/* Appends data to the buffer, expanding it if necessary. */
60
61void
62buffer_append(Buffer *buffer, const void *data, u_int len)
63{
64	void *p;
65	p = buffer_append_space(buffer, len);
66	memcpy(p, data, len);
67}
68
69/*
70 * Appends space to the buffer, expanding the buffer if necessary. This does
71 * not actually copy the data into the buffer, but instead returns a pointer
72 * to the allocated region.
73 */
74
75void *
76buffer_append_space(Buffer *buffer, u_int len)
77{
78	u_int newlen;
79	void *p;
80
81	if (len > 0x100000)
82		fatal("buffer_append_space: len %u not supported", len);
83
84	/* If the buffer is empty, start using it from the beginning. */
85	if (buffer->offset == buffer->end) {
86		buffer->offset = 0;
87		buffer->end = 0;
88	}
89restart:
90	/* If there is enough space to store all data, store it now. */
91	if (buffer->end + len < buffer->alloc) {
92		p = buffer->buf + buffer->end;
93		buffer->end += len;
94		return p;
95	}
96	/*
97	 * If the buffer is quite empty, but all data is at the end, move the
98	 * data to the beginning and retry.
99	 */
100	if (buffer->offset > buffer->alloc / 2) {
101		memmove(buffer->buf, buffer->buf + buffer->offset,
102			buffer->end - buffer->offset);
103		buffer->end -= buffer->offset;
104		buffer->offset = 0;
105		goto restart;
106	}
107	/* Increase the size of the buffer and retry. */
108
109	newlen = buffer->alloc + len + 32768;
110	if (newlen > 0xa00000)
111		fatal("buffer_append_space: alloc %u not supported",
112		    newlen);
113	buffer->buf = xrealloc(buffer->buf, newlen);
114	buffer->alloc = newlen;
115	goto restart;
116	/* NOTREACHED */
117}
118
119/* Returns the number of bytes of data in the buffer. */
120
121u_int
122buffer_len(Buffer *buffer)
123{
124	return buffer->end - buffer->offset;
125}
126
127/* Gets data from the beginning of the buffer. */
128
129int
130buffer_get_ret(Buffer *buffer, void *buf, u_int len)
131{
132	if (len > buffer->end - buffer->offset) {
133		error("buffer_get_ret: trying to get more bytes %d than in buffer %d",
134		    len, buffer->end - buffer->offset);
135		return (-1);
136	}
137	memcpy(buf, buffer->buf + buffer->offset, len);
138	buffer->offset += len;
139	return (0);
140}
141
142void
143buffer_get(Buffer *buffer, void *buf, u_int len)
144{
145	if (buffer_get_ret(buffer, buf, len) == -1)
146		fatal("buffer_get: buffer error");
147}
148
149/* Consumes the given number of bytes from the beginning of the buffer. */
150
151int
152buffer_consume_ret(Buffer *buffer, u_int bytes)
153{
154	if (bytes > buffer->end - buffer->offset) {
155		error("buffer_consume_ret: trying to get more bytes than in buffer");
156		return (-1);
157	}
158	buffer->offset += bytes;
159	return (0);
160}
161
162void
163buffer_consume(Buffer *buffer, u_int bytes)
164{
165	if (buffer_consume_ret(buffer, bytes) == -1)
166		fatal("buffer_consume: buffer error");
167}
168
169/* Consumes the given number of bytes from the end of the buffer. */
170
171int
172buffer_consume_end_ret(Buffer *buffer, u_int bytes)
173{
174	if (bytes > buffer->end - buffer->offset)
175		return (-1);
176	buffer->end -= bytes;
177	return (0);
178}
179
180void
181buffer_consume_end(Buffer *buffer, u_int bytes)
182{
183	if (buffer_consume_end_ret(buffer, bytes) == -1)
184		fatal("buffer_consume_end: trying to get more bytes than in buffer");
185}
186
187/* Returns a pointer to the first used byte in the buffer. */
188
189void *
190buffer_ptr(Buffer *buffer)
191{
192	return buffer->buf + buffer->offset;
193}
194
195/* Dumps the contents of the buffer to stderr. */
196
197void
198buffer_dump(Buffer *buffer)
199{
200	u_int i;
201	u_char *ucp = buffer->buf;
202
203	for (i = buffer->offset; i < buffer->end; i++) {
204		fprintf(stderr, "%02x", ucp[i]);
205		if ((i-buffer->offset)%16==15)
206			fprintf(stderr, "\r\n");
207		else if ((i-buffer->offset)%2==1)
208			fprintf(stderr, " ");
209	}
210	fprintf(stderr, "\r\n");
211}
212