Mike Lockwood | 1305e95 | 2011-12-07 08:17:59 -0800 | [diff] [blame^] | 1 | /* $OpenBSD: buffer.c,v 1.32 2010/02/09 03:56:28 djm 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(const 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(const 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(const 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 | } |