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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 | /* try increasing to 256k in hpnxfers */ | |
30 | #define BUFFER_ALLOCSZ 0x008000 /* 32k */ | |
31 | #define BUFFER_ALLOCSZ_HPN 0x040000 /* 256k */ | |
32 | ||
33 | /* Initializes the buffer structure. */ | |
34 | ||
35 | void | |
36 | buffer_init(Buffer *buffer) | |
37 | { | |
38 | const u_int len = 4096; | |
39 | ||
40 | buffer->alloc = 0; | |
41 | buffer->buf = xmalloc(len); | |
42 | buffer->alloc = len; | |
43 | buffer->offset = 0; | |
44 | buffer->end = 0; | |
45 | } | |
46 | ||
47 | /* Frees any memory used for the buffer. */ | |
48 | ||
49 | void | |
50 | buffer_free(Buffer *buffer) | |
51 | { | |
52 | if (buffer->alloc > 0) { | |
53 | memset(buffer->buf, 0, buffer->alloc); | |
54 | buffer->alloc = 0; | |
55 | xfree(buffer->buf); | |
56 | } | |
57 | } | |
58 | ||
59 | /* | |
60 | * Clears any data from the buffer, making it empty. This does not actually | |
61 | * zero the memory. | |
62 | */ | |
63 | ||
64 | void | |
65 | buffer_clear(Buffer *buffer) | |
66 | { | |
67 | buffer->offset = 0; | |
68 | buffer->end = 0; | |
69 | } | |
70 | ||
71 | /* Appends data to the buffer, expanding it if necessary. */ | |
72 | ||
73 | void | |
74 | buffer_append(Buffer *buffer, const void *data, u_int len) | |
75 | { | |
76 | void *p; | |
77 | p = buffer_append_space(buffer, len); | |
78 | memcpy(p, data, len); | |
79 | } | |
80 | ||
81 | static int | |
82 | buffer_compact(Buffer *buffer) | |
83 | { | |
84 | /* | |
85 | * If the buffer is quite empty, but all data is at the end, move the | |
86 | * data to the beginning. | |
87 | */ | |
88 | if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) { | |
89 | memmove(buffer->buf, buffer->buf + buffer->offset, | |
90 | buffer->end - buffer->offset); | |
91 | buffer->end -= buffer->offset; | |
92 | buffer->offset = 0; | |
93 | return (1); | |
94 | } | |
95 | return (0); | |
96 | } | |
97 | ||
98 | /* | |
99 | * Appends space to the buffer, expanding the buffer if necessary. This does | |
100 | * not actually copy the data into the buffer, but instead returns a pointer | |
101 | * to the allocated region. | |
102 | */ | |
103 | ||
104 | void * | |
105 | buffer_append_space(Buffer *buffer, u_int len) | |
106 | { | |
107 | u_int newlen; | |
108 | u_int buf_max; | |
109 | u_int buf_alloc_sz; | |
110 | void *p; | |
111 | ||
112 | if (len > BUFFER_MAX_CHUNK) | |
113 | fatal("buffer_append_space: len %u not supported", len); | |
114 | ||
115 | /* If the buffer is empty, start using it from the beginning. */ | |
116 | if (buffer->offset == buffer->end) { | |
117 | buffer->offset = 0; | |
118 | buffer->end = 0; | |
119 | } | |
120 | restart: | |
121 | /* If there is enough space to store all data, store it now. */ | |
122 | if (buffer->end + len < buffer->alloc) { | |
123 | p = buffer->buf + buffer->end; | |
124 | buffer->end += len; | |
125 | return p; | |
126 | } | |
127 | ||
128 | /* Compact data back to the start of the buffer if necessary */ | |
129 | if (buffer_compact(buffer)) | |
130 | goto restart; | |
131 | ||
132 | /* if hpn is disabled use the smaller buffer size */ | |
133 | buf_max = BUFFER_MAX_LEN_HPN; | |
134 | buf_alloc_sz = BUFFER_ALLOCSZ_HPN; | |
135 | ||
136 | /* Increase the size of the buffer and retry. */ | |
137 | newlen = roundup(buffer->alloc + len, buf_alloc_sz); | |
138 | ||
139 | ||
140 | if (newlen > buf_max) | |
141 | fatal("buffer_append_space: alloc %u not supported", | |
142 | newlen); | |
143 | buffer->buf = xrealloc(buffer->buf, 1, newlen); | |
144 | buffer->alloc = newlen; | |
145 | goto restart; | |
146 | /* NOTREACHED */ | |
147 | } | |
148 | ||
149 | /* | |
150 | * Check whether an allocation of 'len' will fit in the buffer | |
151 | * This must follow the same math as buffer_append_space | |
152 | */ | |
153 | int | |
154 | buffer_check_alloc(Buffer *buffer, u_int len) | |
155 | { | |
156 | u_int buf_max; | |
157 | u_int buf_alloc_sz; | |
158 | ||
159 | if (buffer->offset == buffer->end) { | |
160 | buffer->offset = 0; | |
161 | buffer->end = 0; | |
162 | } | |
163 | restart: | |
164 | if (buffer->end + len < buffer->alloc) | |
165 | return (1); | |
166 | if (buffer_compact(buffer)) | |
167 | goto restart; | |
168 | ||
169 | /* if hpn is disabled use the smaller buffer size */ | |
170 | buf_max = BUFFER_MAX_LEN_HPN; | |
171 | buf_alloc_sz = BUFFER_ALLOCSZ_HPN; | |
172 | ||
173 | if (roundup(buffer->alloc + len, buf_alloc_sz) <= buf_max) | |
174 | return (1); | |
175 | return (0); | |
176 | } | |
177 | ||
178 | /* Returns the number of bytes of data in the buffer. */ | |
179 | ||
180 | u_int | |
181 | buffer_len(Buffer *buffer) | |
182 | { | |
183 | return buffer->end - buffer->offset; | |
184 | } | |
185 | ||
186 | /* Gets data from the beginning of the buffer. */ | |
187 | ||
188 | int | |
189 | buffer_get_ret(Buffer *buffer, void *buf, u_int len) | |
190 | { | |
191 | if (len > buffer->end - buffer->offset) { | |
192 | error("buffer_get_ret: trying to get more bytes %d than in buffer %d", | |
193 | len, buffer->end - buffer->offset); | |
194 | return (-1); | |
195 | } | |
196 | memcpy(buf, buffer->buf + buffer->offset, len); | |
197 | buffer->offset += len; | |
198 | return (0); | |
199 | } | |
200 | ||
201 | void | |
202 | buffer_get(Buffer *buffer, void *buf, u_int len) | |
203 | { | |
204 | if (buffer_get_ret(buffer, buf, len) == -1) | |
205 | fatal("buffer_get: buffer error"); | |
206 | } | |
207 | ||
208 | /* Consumes the given number of bytes from the beginning of the buffer. */ | |
209 | ||
210 | int | |
211 | buffer_consume_ret(Buffer *buffer, u_int bytes) | |
212 | { | |
213 | if (bytes > buffer->end - buffer->offset) { | |
214 | error("buffer_consume_ret: trying to get more bytes than in buffer"); | |
215 | return (-1); | |
216 | } | |
217 | buffer->offset += bytes; | |
218 | return (0); | |
219 | } | |
220 | ||
221 | void | |
222 | buffer_consume(Buffer *buffer, u_int bytes) | |
223 | { | |
224 | if (buffer_consume_ret(buffer, bytes) == -1) | |
225 | fatal("buffer_consume: buffer error"); | |
226 | } | |
227 | ||
228 | /* Consumes the given number of bytes from the end of the buffer. */ | |
229 | ||
230 | int | |
231 | buffer_consume_end_ret(Buffer *buffer, u_int bytes) | |
232 | { | |
233 | if (bytes > buffer->end - buffer->offset) | |
234 | return (-1); | |
235 | buffer->end -= bytes; | |
236 | return (0); | |
237 | } | |
238 | ||
239 | void | |
240 | buffer_consume_end(Buffer *buffer, u_int bytes) | |
241 | { | |
242 | if (buffer_consume_end_ret(buffer, bytes) == -1) | |
243 | fatal("buffer_consume_end: trying to get more bytes than in buffer"); | |
244 | } | |
245 | ||
246 | /* Returns a pointer to the first used byte in the buffer. */ | |
247 | ||
248 | void * | |
249 | buffer_ptr(Buffer *buffer) | |
250 | { | |
251 | return buffer->buf + buffer->offset; | |
252 | } | |
253 | ||
254 | /* Dumps the contents of the buffer to stderr. */ | |
255 | ||
256 | void | |
257 | buffer_dump(Buffer *buffer) | |
258 | { | |
259 | u_int i; | |
260 | u_char *ucp = buffer->buf; | |
261 | ||
262 | for (i = buffer->offset; i < buffer->end; i++) { | |
263 | fprintf(stderr, "%02x", ucp[i]); | |
264 | if ((i-buffer->offset)%16==15) | |
265 | fprintf(stderr, "\r\n"); | |
266 | else if ((i-buffer->offset)%2==1) | |
267 | fprintf(stderr, " "); | |
268 | } | |
269 | fprintf(stderr, "\r\n"); | |
270 | } |