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30460aeb | 1 | /* $OpenBSD: buffer.c,v 1.31 2006/08/03 03:34:41 deraadt Exp $ */ |
3c0ef626 | 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" | |
30460aeb | 16 | |
17 | #include <sys/param.h> | |
18 | ||
19 | #include <stdio.h> | |
20 | #include <string.h> | |
21 | #include <stdarg.h> | |
3c0ef626 | 22 | |
23 | #include "xmalloc.h" | |
24 | #include "buffer.h" | |
25 | #include "log.h" | |
26 | ||
30460aeb | 27 | #define BUFFER_MAX_CHUNK 0x100000 |
28 | #define BUFFER_MAX_LEN 0xa00000 | |
6df46d40 | 29 | #define BUFFER_ALLOCSZ 0x008000 |
30460aeb | 30 | |
3c0ef626 | 31 | /* Initializes the buffer structure. */ |
32 | ||
33 | void | |
34 | buffer_init(Buffer *buffer) | |
35 | { | |
473db5ab | 36 | const u_int len = 4096; |
37 | ||
38 | buffer->alloc = 0; | |
39 | buffer->buf = xmalloc(len); | |
40 | buffer->alloc = len; | |
3c0ef626 | 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 | { | |
473db5ab | 50 | if (buffer->alloc > 0) { |
51 | memset(buffer->buf, 0, buffer->alloc); | |
52 | buffer->alloc = 0; | |
53 | xfree(buffer->buf); | |
54 | } | |
3c0ef626 | 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 | |
473db5ab | 72 | buffer_append(Buffer *buffer, const void *data, u_int len) |
3c0ef626 | 73 | { |
473db5ab | 74 | void *p; |
75 | p = buffer_append_space(buffer, len); | |
76 | memcpy(p, data, len); | |
3c0ef626 | 77 | } |
78 | ||
30460aeb | 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 | ||
3c0ef626 | 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 | ||
473db5ab | 102 | void * |
103 | buffer_append_space(Buffer *buffer, u_int len) | |
3c0ef626 | 104 | { |
473db5ab | 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 | ||
3c0ef626 | 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) { | |
473db5ab | 119 | p = buffer->buf + buffer->end; |
3c0ef626 | 120 | buffer->end += len; |
473db5ab | 121 | return p; |
3c0ef626 | 122 | } |
30460aeb | 123 | |
124 | /* Compact data back to the start of the buffer if necessary */ | |
125 | if (buffer_compact(buffer)) | |
3c0ef626 | 126 | goto restart; |
473db5ab | 127 | |
30460aeb | 128 | /* Increase the size of the buffer and retry. */ |
6df46d40 | 129 | newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ); |
d3057ca4 | 130 | if (newlen > BUFFER_MAX_LEN_HPN) |
473db5ab | 131 | fatal("buffer_append_space: alloc %u not supported", |
132 | newlen); | |
30460aeb | 133 | buffer->buf = xrealloc(buffer->buf, 1, newlen); |
473db5ab | 134 | buffer->alloc = newlen; |
3c0ef626 | 135 | goto restart; |
473db5ab | 136 | /* NOTREACHED */ |
3c0ef626 | 137 | } |
138 | ||
30460aeb | 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; | |
6df46d40 | 155 | if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN) |
30460aeb | 156 | return (1); |
157 | return (0); | |
158 | } | |
159 | ||
3c0ef626 | 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 | ||
473db5ab | 170 | int |
171 | buffer_get_ret(Buffer *buffer, void *buf, u_int len) | |
3c0ef626 | 172 | { |
473db5ab | 173 | if (len > buffer->end - buffer->offset) { |
174 | error("buffer_get_ret: trying to get more bytes %d than in buffer %d", | |
3c0ef626 | 175 | len, buffer->end - buffer->offset); |
473db5ab | 176 | return (-1); |
177 | } | |
3c0ef626 | 178 | memcpy(buf, buffer->buf + buffer->offset, len); |
179 | buffer->offset += len; | |
473db5ab | 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"); | |
3c0ef626 | 188 | } |
189 | ||
190 | /* Consumes the given number of bytes from the beginning of the buffer. */ | |
191 | ||
473db5ab | 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 | ||
3c0ef626 | 203 | void |
204 | buffer_consume(Buffer *buffer, u_int bytes) | |
205 | { | |
473db5ab | 206 | if (buffer_consume_ret(buffer, bytes) == -1) |
207 | fatal("buffer_consume: buffer error"); | |
3c0ef626 | 208 | } |
209 | ||
210 | /* Consumes the given number of bytes from the end of the buffer. */ | |
211 | ||
473db5ab | 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 | ||
3c0ef626 | 221 | void |
222 | buffer_consume_end(Buffer *buffer, u_int bytes) | |
223 | { | |
473db5ab | 224 | if (buffer_consume_end_ret(buffer, bytes) == -1) |
3c0ef626 | 225 | fatal("buffer_consume_end: trying to get more bytes than in buffer"); |
3c0ef626 | 226 | } |
227 | ||
228 | /* Returns a pointer to the first used byte in the buffer. */ | |
229 | ||
473db5ab | 230 | void * |
3c0ef626 | 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 | { | |
473db5ab | 241 | u_int i; |
242 | u_char *ucp = buffer->buf; | |
3c0ef626 | 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 | } |