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69d9d413 | 1 | /* $OpenBSD: buffer.c,v 1.27 2006/04/16 00:48:52 djm Exp $ */ |
8efc0c15 | 2 | /* |
5260325f | 3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
5 | * All rights reserved | |
5260325f | 6 | * Functions for manipulating fifo buffers (that can grow if needed). |
6ae2364d | 7 | * |
bcbf86ec | 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". | |
5260325f | 13 | */ |
8efc0c15 | 14 | |
15 | #include "includes.h" | |
8efc0c15 | 16 | |
17 | #include "xmalloc.h" | |
18 | #include "buffer.h" | |
42f11eb2 | 19 | #include "log.h" |
8efc0c15 | 20 | |
69d9d413 | 21 | #define BUFFER_MAX_CHUNK 0x100000 |
22 | #define BUFFER_MAX_LEN 0xa00000 | |
23 | #define BUFFER_ALLOCSZ 0x008000 | |
24 | ||
8efc0c15 | 25 | /* Initializes the buffer structure. */ |
26 | ||
6ae2364d | 27 | void |
5260325f | 28 | buffer_init(Buffer *buffer) |
8efc0c15 | 29 | { |
20419cc1 | 30 | const u_int len = 4096; |
31 | ||
32 | buffer->alloc = 0; | |
33 | buffer->buf = xmalloc(len); | |
34 | buffer->alloc = len; | |
5260325f | 35 | buffer->offset = 0; |
36 | buffer->end = 0; | |
8efc0c15 | 37 | } |
38 | ||
39 | /* Frees any memory used for the buffer. */ | |
40 | ||
6ae2364d | 41 | void |
5260325f | 42 | buffer_free(Buffer *buffer) |
8efc0c15 | 43 | { |
20419cc1 | 44 | if (buffer->alloc > 0) { |
45 | memset(buffer->buf, 0, buffer->alloc); | |
5bd34316 | 46 | buffer->alloc = 0; |
20419cc1 | 47 | xfree(buffer->buf); |
48 | } | |
8efc0c15 | 49 | } |
50 | ||
aa3378df | 51 | /* |
52 | * Clears any data from the buffer, making it empty. This does not actually | |
53 | * zero the memory. | |
54 | */ | |
8efc0c15 | 55 | |
6ae2364d | 56 | void |
5260325f | 57 | buffer_clear(Buffer *buffer) |
8efc0c15 | 58 | { |
5260325f | 59 | buffer->offset = 0; |
60 | buffer->end = 0; | |
8efc0c15 | 61 | } |
62 | ||
63 | /* Appends data to the buffer, expanding it if necessary. */ | |
64 | ||
6ae2364d | 65 | void |
6c0fa2b1 | 66 | buffer_append(Buffer *buffer, const void *data, u_int len) |
8efc0c15 | 67 | { |
6c0fa2b1 | 68 | void *p; |
69 | p = buffer_append_space(buffer, len); | |
70 | memcpy(p, data, len); | |
8efc0c15 | 71 | } |
72 | ||
69d9d413 | 73 | static int |
74 | buffer_compact(Buffer *buffer) | |
75 | { | |
76 | /* | |
77 | * If the buffer is quite empty, but all data is at the end, move the | |
78 | * data to the beginning. | |
79 | */ | |
80 | if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) { | |
81 | memmove(buffer->buf, buffer->buf + buffer->offset, | |
82 | buffer->end - buffer->offset); | |
83 | buffer->end -= buffer->offset; | |
84 | buffer->offset = 0; | |
85 | return (1); | |
86 | } | |
87 | return (0); | |
88 | } | |
89 | ||
aa3378df | 90 | /* |
91 | * Appends space to the buffer, expanding the buffer if necessary. This does | |
92 | * not actually copy the data into the buffer, but instead returns a pointer | |
93 | * to the allocated region. | |
94 | */ | |
8efc0c15 | 95 | |
6c0fa2b1 | 96 | void * |
97 | buffer_append_space(Buffer *buffer, u_int len) | |
8efc0c15 | 98 | { |
49525395 | 99 | u_int newlen; |
6c0fa2b1 | 100 | void *p; |
101 | ||
fa1d7d85 | 102 | if (len > BUFFER_MAX_CHUNK) |
22d62d31 | 103 | fatal("buffer_append_space: len %u not supported", len); |
104 | ||
5260325f | 105 | /* If the buffer is empty, start using it from the beginning. */ |
106 | if (buffer->offset == buffer->end) { | |
107 | buffer->offset = 0; | |
108 | buffer->end = 0; | |
109 | } | |
110 | restart: | |
111 | /* If there is enough space to store all data, store it now. */ | |
112 | if (buffer->end + len < buffer->alloc) { | |
6c0fa2b1 | 113 | p = buffer->buf + buffer->end; |
5260325f | 114 | buffer->end += len; |
6c0fa2b1 | 115 | return p; |
5260325f | 116 | } |
69d9d413 | 117 | |
118 | /* Compact data back to the start of the buffer if necessary */ | |
119 | if (buffer_compact(buffer)) | |
5260325f | 120 | goto restart; |
b6453d99 | 121 | |
69d9d413 | 122 | /* Increase the size of the buffer and retry. */ |
123 | newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ); | |
fa1d7d85 | 124 | if (newlen > BUFFER_MAX_LEN) |
22d62d31 | 125 | fatal("buffer_append_space: alloc %u not supported", |
49525395 | 126 | newlen); |
c5d10563 | 127 | buffer->buf = xrealloc(buffer->buf, 1, newlen); |
49525395 | 128 | buffer->alloc = newlen; |
5260325f | 129 | goto restart; |
6c0fa2b1 | 130 | /* NOTREACHED */ |
8efc0c15 | 131 | } |
132 | ||
69d9d413 | 133 | /* |
134 | * Check whether an allocation of 'len' will fit in the buffer | |
135 | * This must follow the same math as buffer_append_space | |
136 | */ | |
137 | int | |
138 | buffer_check_alloc(Buffer *buffer, u_int len) | |
139 | { | |
140 | if (buffer->offset == buffer->end) { | |
141 | buffer->offset = 0; | |
142 | buffer->end = 0; | |
143 | } | |
144 | restart: | |
145 | if (buffer->end + len < buffer->alloc) | |
146 | return (1); | |
147 | if (buffer_compact(buffer)) | |
148 | goto restart; | |
149 | if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN) | |
150 | return (1); | |
151 | return (0); | |
152 | } | |
153 | ||
8efc0c15 | 154 | /* Returns the number of bytes of data in the buffer. */ |
155 | ||
1e3b8b07 | 156 | u_int |
5260325f | 157 | buffer_len(Buffer *buffer) |
8efc0c15 | 158 | { |
5260325f | 159 | return buffer->end - buffer->offset; |
8efc0c15 | 160 | } |
161 | ||
162 | /* Gets data from the beginning of the buffer. */ | |
163 | ||
b82a59f2 | 164 | int |
165 | buffer_get_ret(Buffer *buffer, void *buf, u_int len) | |
8efc0c15 | 166 | { |
b82a59f2 | 167 | if (len > buffer->end - buffer->offset) { |
168 | error("buffer_get_ret: trying to get more bytes %d than in buffer %d", | |
b37caf1a | 169 | len, buffer->end - buffer->offset); |
b82a59f2 | 170 | return (-1); |
171 | } | |
5260325f | 172 | memcpy(buf, buffer->buf + buffer->offset, len); |
173 | buffer->offset += len; | |
b82a59f2 | 174 | return (0); |
175 | } | |
176 | ||
177 | void | |
178 | buffer_get(Buffer *buffer, void *buf, u_int len) | |
179 | { | |
180 | if (buffer_get_ret(buffer, buf, len) == -1) | |
181 | fatal("buffer_get: buffer error"); | |
8efc0c15 | 182 | } |
183 | ||
184 | /* Consumes the given number of bytes from the beginning of the buffer. */ | |
185 | ||
b82a59f2 | 186 | int |
187 | buffer_consume_ret(Buffer *buffer, u_int bytes) | |
188 | { | |
189 | if (bytes > buffer->end - buffer->offset) { | |
190 | error("buffer_consume_ret: trying to get more bytes than in buffer"); | |
191 | return (-1); | |
192 | } | |
193 | buffer->offset += bytes; | |
194 | return (0); | |
195 | } | |
196 | ||
6ae2364d | 197 | void |
1e3b8b07 | 198 | buffer_consume(Buffer *buffer, u_int bytes) |
8efc0c15 | 199 | { |
b82a59f2 | 200 | if (buffer_consume_ret(buffer, bytes) == -1) |
201 | fatal("buffer_consume: buffer error"); | |
5260325f | 202 | } |
8efc0c15 | 203 | |
204 | /* Consumes the given number of bytes from the end of the buffer. */ | |
205 | ||
b82a59f2 | 206 | int |
207 | buffer_consume_end_ret(Buffer *buffer, u_int bytes) | |
208 | { | |
209 | if (bytes > buffer->end - buffer->offset) | |
210 | return (-1); | |
211 | buffer->end -= bytes; | |
212 | return (0); | |
213 | } | |
214 | ||
6ae2364d | 215 | void |
1e3b8b07 | 216 | buffer_consume_end(Buffer *buffer, u_int bytes) |
8efc0c15 | 217 | { |
b82a59f2 | 218 | if (buffer_consume_end_ret(buffer, bytes) == -1) |
f54651ce | 219 | fatal("buffer_consume_end: trying to get more bytes than in buffer"); |
5260325f | 220 | } |
8efc0c15 | 221 | |
222 | /* Returns a pointer to the first used byte in the buffer. */ | |
223 | ||
6c0fa2b1 | 224 | void * |
5260325f | 225 | buffer_ptr(Buffer *buffer) |
8efc0c15 | 226 | { |
5260325f | 227 | return buffer->buf + buffer->offset; |
8efc0c15 | 228 | } |
229 | ||
230 | /* Dumps the contents of the buffer to stderr. */ | |
231 | ||
6ae2364d | 232 | void |
5260325f | 233 | buffer_dump(Buffer *buffer) |
8efc0c15 | 234 | { |
f04181fe | 235 | u_int i; |
e6207598 | 236 | u_char *ucp = buffer->buf; |
5260325f | 237 | |
8002af61 | 238 | for (i = buffer->offset; i < buffer->end; i++) { |
239 | fprintf(stderr, "%02x", ucp[i]); | |
240 | if ((i-buffer->offset)%16==15) | |
241 | fprintf(stderr, "\r\n"); | |
242 | else if ((i-buffer->offset)%2==1) | |
243 | fprintf(stderr, " "); | |
244 | } | |
0490e609 | 245 | fprintf(stderr, "\r\n"); |
8efc0c15 | 246 | } |