1 /* $OpenBSD: buffer.c,v 1.32 2010/02/09 03:56:28 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) 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 } 253
