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1 | /* $OpenBSD: buffer.c,v 1.31 2006/08/03 03:34:41 deraadt Exp $ */ | |
2 | /* | |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * Functions for manipulating fifo buffers (that can grow if needed). | |
7 | * | |
8 | * As far as I am concerned, the code I have written for this software | |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
13 | */ | |
14 | ||
15 | #include "includes.h" | |
16 | ||
17 | #include <sys/param.h> | |
18 | ||
19 | #include <stdio.h> | |
20 | #include <string.h> | |
21 | #include <stdarg.h> | |
22 | ||
23 | #include "xmalloc.h" | |
24 | #include "buffer.h" | |
25 | #include "log.h" | |
26 | ||
27 | #define BUFFER_MAX_CHUNK 0x100000 | |
28 | #define BUFFER_MAX_LEN 0xa00000 | |
29 | #define BUFFER_ALLOCSZ 0x008000 | |
30 | ||
31 | /* Initializes the buffer structure. */ | |
32 | ||
33 | void | |
34 | buffer_init(Buffer *buffer) | |
35 | { | |
36 | const u_int len = 4096; | |
37 | ||
38 | buffer->alloc = 0; | |
39 | buffer->buf = xmalloc(len); | |
40 | buffer->alloc = len; | |
41 | buffer->offset = 0; | |
42 | buffer->end = 0; | |
43 | } | |
44 | ||
45 | /* Frees any memory used for the buffer. */ | |
46 | ||
47 | void | |
48 | buffer_free(Buffer *buffer) | |
49 | { | |
50 | if (buffer->alloc > 0) { | |
51 | memset(buffer->buf, 0, buffer->alloc); | |
52 | buffer->alloc = 0; | |
53 | xfree(buffer->buf); | |
54 | } | |
55 | } | |
56 | ||
57 | /* | |
58 | * Clears any data from the buffer, making it empty. This does not actually | |
59 | * zero the memory. | |
60 | */ | |
61 | ||
62 | void | |
63 | buffer_clear(Buffer *buffer) | |
64 | { | |
65 | buffer->offset = 0; | |
66 | buffer->end = 0; | |
67 | } | |
68 | ||
69 | /* Appends data to the buffer, expanding it if necessary. */ | |
70 | ||
71 | void | |
72 | buffer_append(Buffer *buffer, const void *data, u_int len) | |
73 | { | |
74 | void *p; | |
75 | p = buffer_append_space(buffer, len); | |
76 | memcpy(p, data, len); | |
77 | } | |
78 | ||
79 | static int | |
80 | buffer_compact(Buffer *buffer) | |
81 | { | |
82 | /* | |
83 | * If the buffer is quite empty, but all data is at the end, move the | |
84 | * data to the beginning. | |
85 | */ | |
86 | if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) { | |
87 | memmove(buffer->buf, buffer->buf + buffer->offset, | |
88 | buffer->end - buffer->offset); | |
89 | buffer->end -= buffer->offset; | |
90 | buffer->offset = 0; | |
91 | return (1); | |
92 | } | |
93 | return (0); | |
94 | } | |
95 | ||
96 | /* | |
97 | * Appends space to the buffer, expanding the buffer if necessary. This does | |
98 | * not actually copy the data into the buffer, but instead returns a pointer | |
99 | * to the allocated region. | |
100 | */ | |
101 | ||
102 | void * | |
103 | buffer_append_space(Buffer *buffer, u_int len) | |
104 | { | |
105 | u_int newlen; | |
106 | void *p; | |
107 | ||
108 | if (len > BUFFER_MAX_CHUNK) | |
109 | fatal("buffer_append_space: len %u not supported", len); | |
110 | ||
111 | /* If the buffer is empty, start using it from the beginning. */ | |
112 | if (buffer->offset == buffer->end) { | |
113 | buffer->offset = 0; | |
114 | buffer->end = 0; | |
115 | } | |
116 | restart: | |
117 | /* If there is enough space to store all data, store it now. */ | |
118 | if (buffer->end + len < buffer->alloc) { | |
119 | p = buffer->buf + buffer->end; | |
120 | buffer->end += len; | |
121 | return p; | |
122 | } | |
123 | ||
124 | /* Compact data back to the start of the buffer if necessary */ | |
125 | if (buffer_compact(buffer)) | |
126 | goto restart; | |
127 | ||
128 | /* Increase the size of the buffer and retry. */ | |
129 | newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ); | |
130 | if (newlen > BUFFER_MAX_LEN) | |
131 | fatal("buffer_append_space: alloc %u not supported", | |
132 | newlen); | |
133 | buffer->buf = xrealloc(buffer->buf, 1, newlen); | |
134 | buffer->alloc = newlen; | |
135 | goto restart; | |
136 | /* NOTREACHED */ | |
137 | } | |
138 | ||
139 | /* | |
140 | * Check whether an allocation of 'len' will fit in the buffer | |
141 | * This must follow the same math as buffer_append_space | |
142 | */ | |
143 | int | |
144 | buffer_check_alloc(Buffer *buffer, u_int len) | |
145 | { | |
146 | if (buffer->offset == buffer->end) { | |
147 | buffer->offset = 0; | |
148 | buffer->end = 0; | |
149 | } | |
150 | restart: | |
151 | if (buffer->end + len < buffer->alloc) | |
152 | return (1); | |
153 | if (buffer_compact(buffer)) | |
154 | goto restart; | |
155 | if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN) | |
156 | return (1); | |
157 | return (0); | |
158 | } | |
159 | ||
160 | /* Returns the number of bytes of data in the buffer. */ | |
161 | ||
162 | u_int | |
163 | buffer_len(Buffer *buffer) | |
164 | { | |
165 | return buffer->end - buffer->offset; | |
166 | } | |
167 | ||
168 | /* Gets data from the beginning of the buffer. */ | |
169 | ||
170 | int | |
171 | buffer_get_ret(Buffer *buffer, void *buf, u_int len) | |
172 | { | |
173 | if (len > buffer->end - buffer->offset) { | |
174 | error("buffer_get_ret: trying to get more bytes %d than in buffer %d", | |
175 | len, buffer->end - buffer->offset); | |
176 | return (-1); | |
177 | } | |
178 | memcpy(buf, buffer->buf + buffer->offset, len); | |
179 | buffer->offset += len; | |
180 | return (0); | |
181 | } | |
182 | ||
183 | void | |
184 | buffer_get(Buffer *buffer, void *buf, u_int len) | |
185 | { | |
186 | if (buffer_get_ret(buffer, buf, len) == -1) | |
187 | fatal("buffer_get: buffer error"); | |
188 | } | |
189 | ||
190 | /* Consumes the given number of bytes from the beginning of the buffer. */ | |
191 | ||
192 | int | |
193 | buffer_consume_ret(Buffer *buffer, u_int bytes) | |
194 | { | |
195 | if (bytes > buffer->end - buffer->offset) { | |
196 | error("buffer_consume_ret: trying to get more bytes than in buffer"); | |
197 | return (-1); | |
198 | } | |
199 | buffer->offset += bytes; | |
200 | return (0); | |
201 | } | |
202 | ||
203 | void | |
204 | buffer_consume(Buffer *buffer, u_int bytes) | |
205 | { | |
206 | if (buffer_consume_ret(buffer, bytes) == -1) | |
207 | fatal("buffer_consume: buffer error"); | |
208 | } | |
209 | ||
210 | /* Consumes the given number of bytes from the end of the buffer. */ | |
211 | ||
212 | int | |
213 | buffer_consume_end_ret(Buffer *buffer, u_int bytes) | |
214 | { | |
215 | if (bytes > buffer->end - buffer->offset) | |
216 | return (-1); | |
217 | buffer->end -= bytes; | |
218 | return (0); | |
219 | } | |
220 | ||
221 | void | |
222 | buffer_consume_end(Buffer *buffer, u_int bytes) | |
223 | { | |
224 | if (buffer_consume_end_ret(buffer, bytes) == -1) | |
225 | fatal("buffer_consume_end: trying to get more bytes than in buffer"); | |
226 | } | |
227 | ||
228 | /* Returns a pointer to the first used byte in the buffer. */ | |
229 | ||
230 | void * | |
231 | buffer_ptr(Buffer *buffer) | |
232 | { | |
233 | return buffer->buf + buffer->offset; | |
234 | } | |
235 | ||
236 | /* Dumps the contents of the buffer to stderr. */ | |
237 | ||
238 | void | |
239 | buffer_dump(Buffer *buffer) | |
240 | { | |
241 | u_int i; | |
242 | u_char *ucp = buffer->buf; | |
243 | ||
244 | for (i = buffer->offset; i < buffer->end; i++) { | |
245 | fprintf(stderr, "%02x", ucp[i]); | |
246 | if ((i-buffer->offset)%16==15) | |
247 | fprintf(stderr, "\r\n"); | |
248 | else if ((i-buffer->offset)%2==1) | |
249 | fprintf(stderr, " "); | |
250 | } | |
251 | fprintf(stderr, "\r\n"); | |
252 | } |