base32.c revision 1.1
1/* $NetBSD: base32.c,v 1.1 2024/02/18 20:57:48 christos Exp $ */ 2 3/* 4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC") 5 * 6 * SPDX-License-Identifier: MPL-2.0 7 * 8 * This Source Code Form is subject to the terms of the Mozilla Public 9 * License, v. 2.0. If a copy of the MPL was not distributed with this 10 * file, you can obtain one at https://mozilla.org/MPL/2.0/. 11 * 12 * See the COPYRIGHT file distributed with this work for additional 13 * information regarding copyright ownership. 14 */ 15 16/*! \file */ 17 18#include <stdbool.h> 19 20#include <isc/base32.h> 21#include <isc/buffer.h> 22#include <isc/lex.h> 23#include <isc/region.h> 24#include <isc/string.h> 25#include <isc/util.h> 26 27#define RETERR(x) \ 28 do { \ 29 isc_result_t _r = (x); \ 30 if (_r != ISC_R_SUCCESS) \ 31 return ((_r)); \ 32 } while (0) 33 34/*@{*/ 35/*! 36 * These static functions are also present in lib/dns/rdata.c. I'm not 37 * sure where they should go. -- bwelling 38 */ 39static isc_result_t 40str_totext(const char *source, isc_buffer_t *target); 41 42static isc_result_t 43mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length); 44 45/*@}*/ 46 47static const char base32[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=" 48 "abcdefghijklmnopqrstuvwxyz234567"; 49static const char base32hex[] = "0123456789ABCDEFGHIJKLMNOPQRSTUV=" 50 "0123456789abcdefghijklmnopqrstuv"; 51 52static isc_result_t 53base32_totext(isc_region_t *source, int wordlength, const char *wordbreak, 54 isc_buffer_t *target, const char base[], char pad) { 55 char buf[9]; 56 unsigned int loops = 0; 57 58 if (wordlength >= 0 && wordlength < 8) { 59 wordlength = 8; 60 } 61 62 memset(buf, 0, sizeof(buf)); 63 while (source->length > 0) { 64 buf[0] = base[((source->base[0] >> 3) & 0x1f)]; /* 5 + */ 65 if (source->length == 1) { 66 buf[1] = base[(source->base[0] << 2) & 0x1c]; 67 buf[2] = buf[3] = buf[4] = pad; 68 buf[5] = buf[6] = buf[7] = pad; 69 RETERR(str_totext(buf, target)); 70 break; 71 } 72 buf[1] = base[((source->base[0] << 2) & 0x1c) | /* 3 = 8 */ 73 ((source->base[1] >> 6) & 0x03)]; /* 2 + */ 74 buf[2] = base[((source->base[1] >> 1) & 0x1f)]; /* 5 + */ 75 if (source->length == 2) { 76 buf[3] = base[(source->base[1] << 4) & 0x10]; 77 buf[4] = buf[5] = buf[6] = buf[7] = pad; 78 RETERR(str_totext(buf, target)); 79 break; 80 } 81 buf[3] = base[((source->base[1] << 4) & 0x10) | /* 1 = 8 */ 82 ((source->base[2] >> 4) & 0x0f)]; /* 4 + */ 83 if (source->length == 3) { 84 buf[4] = base[(source->base[2] << 1) & 0x1e]; 85 buf[5] = buf[6] = buf[7] = pad; 86 RETERR(str_totext(buf, target)); 87 break; 88 } 89 buf[4] = base[((source->base[2] << 1) & 0x1e) | /* 4 = 8 */ 90 ((source->base[3] >> 7) & 0x01)]; /* 1 + */ 91 buf[5] = base[((source->base[3] >> 2) & 0x1f)]; /* 5 + */ 92 if (source->length == 4) { 93 buf[6] = base[(source->base[3] << 3) & 0x18]; 94 buf[7] = pad; 95 RETERR(str_totext(buf, target)); 96 break; 97 } 98 buf[6] = base[((source->base[3] << 3) & 0x18) | /* 2 = 8 */ 99 ((source->base[4] >> 5) & 0x07)]; /* 3 + */ 100 buf[7] = base[source->base[4] & 0x1f]; /* 5 = 8 */ 101 RETERR(str_totext(buf, target)); 102 isc_region_consume(source, 5); 103 104 loops++; 105 if (source->length != 0 && wordlength >= 0 && 106 (int)((loops + 1) * 8) >= wordlength) 107 { 108 loops = 0; 109 RETERR(str_totext(wordbreak, target)); 110 } 111 } 112 if (source->length > 0) { 113 isc_region_consume(source, source->length); 114 } 115 return (ISC_R_SUCCESS); 116} 117 118isc_result_t 119isc_base32_totext(isc_region_t *source, int wordlength, const char *wordbreak, 120 isc_buffer_t *target) { 121 return (base32_totext(source, wordlength, wordbreak, target, base32, 122 '=')); 123} 124 125isc_result_t 126isc_base32hex_totext(isc_region_t *source, int wordlength, 127 const char *wordbreak, isc_buffer_t *target) { 128 return (base32_totext(source, wordlength, wordbreak, target, base32hex, 129 '=')); 130} 131 132isc_result_t 133isc_base32hexnp_totext(isc_region_t *source, int wordlength, 134 const char *wordbreak, isc_buffer_t *target) { 135 return (base32_totext(source, wordlength, wordbreak, target, base32hex, 136 0)); 137} 138 139/*% 140 * State of a base32 decoding process in progress. 141 */ 142typedef struct { 143 int length; /*%< Desired length of binary data or -1 */ 144 isc_buffer_t *target; /*%< Buffer for resulting binary data */ 145 int digits; /*%< Number of buffered base32 digits */ 146 bool seen_end; /*%< True if "=" end marker seen */ 147 int val[8]; 148 const char *base; /*%< Which encoding we are using */ 149 int seen_32; /*%< Number of significant bytes if non 150 * zero */ 151 bool pad; /*%< Expect padding */ 152} base32_decode_ctx_t; 153 154static void 155base32_decode_init(base32_decode_ctx_t *ctx, int length, const char base[], 156 bool pad, isc_buffer_t *target) { 157 ctx->digits = 0; 158 ctx->seen_end = false; 159 ctx->seen_32 = 0; 160 ctx->length = length; 161 ctx->target = target; 162 ctx->base = base; 163 ctx->pad = pad; 164} 165 166static isc_result_t 167base32_decode_char(base32_decode_ctx_t *ctx, int c) { 168 const char *s; 169 unsigned int last; 170 171 if (ctx->seen_end) { 172 return (ISC_R_BADBASE32); 173 } 174 if ((s = strchr(ctx->base, c)) == NULL) { 175 return (ISC_R_BADBASE32); 176 } 177 last = (unsigned int)(s - ctx->base); 178 179 /* 180 * Handle lower case. 181 */ 182 if (last > 32) { 183 last -= 33; 184 } 185 186 /* 187 * Check that padding is contiguous. 188 */ 189 if (last != 32 && ctx->seen_32 != 0) { 190 return (ISC_R_BADBASE32); 191 } 192 193 /* 194 * If padding is not permitted flag padding as a error. 195 */ 196 if (last == 32 && !ctx->pad) { 197 return (ISC_R_BADBASE32); 198 } 199 200 /* 201 * Check that padding starts at the right place and that 202 * bits that should be zero are. 203 * Record how many significant bytes in answer (seen_32). 204 */ 205 if (last == 32 && ctx->seen_32 == 0) { 206 switch (ctx->digits) { 207 case 0: 208 case 1: 209 return (ISC_R_BADBASE32); 210 case 2: 211 if ((ctx->val[1] & 0x03) != 0) { 212 return (ISC_R_BADBASE32); 213 } 214 ctx->seen_32 = 1; 215 break; 216 case 3: 217 return (ISC_R_BADBASE32); 218 case 4: 219 if ((ctx->val[3] & 0x0f) != 0) { 220 return (ISC_R_BADBASE32); 221 } 222 ctx->seen_32 = 2; 223 break; 224 case 5: 225 if ((ctx->val[4] & 0x01) != 0) { 226 return (ISC_R_BADBASE32); 227 } 228 ctx->seen_32 = 3; 229 break; 230 case 6: 231 return (ISC_R_BADBASE32); 232 case 7: 233 if ((ctx->val[6] & 0x07) != 0) { 234 return (ISC_R_BADBASE32); 235 } 236 ctx->seen_32 = 4; 237 break; 238 } 239 } 240 241 /* 242 * Zero fill pad values. 243 */ 244 ctx->val[ctx->digits++] = (last == 32) ? 0 : last; 245 246 if (ctx->digits == 8) { 247 int n = 5; 248 unsigned char buf[5]; 249 250 if (ctx->seen_32 != 0) { 251 ctx->seen_end = true; 252 n = ctx->seen_32; 253 } 254 buf[0] = (ctx->val[0] << 3) | (ctx->val[1] >> 2); 255 buf[1] = (ctx->val[1] << 6) | (ctx->val[2] << 1) | 256 (ctx->val[3] >> 4); 257 buf[2] = (ctx->val[3] << 4) | (ctx->val[4] >> 1); 258 buf[3] = (ctx->val[4] << 7) | (ctx->val[5] << 2) | 259 (ctx->val[6] >> 3); 260 buf[4] = (ctx->val[6] << 5) | (ctx->val[7]); 261 RETERR(mem_tobuffer(ctx->target, buf, n)); 262 if (ctx->length >= 0) { 263 if (n > ctx->length) { 264 return (ISC_R_BADBASE32); 265 } else { 266 ctx->length -= n; 267 } 268 } 269 ctx->digits = 0; 270 } 271 return (ISC_R_SUCCESS); 272} 273 274static isc_result_t 275base32_decode_finish(base32_decode_ctx_t *ctx) { 276 if (ctx->length > 0) { 277 return (ISC_R_UNEXPECTEDEND); 278 } 279 /* 280 * Add missing padding if required. 281 */ 282 if (!ctx->pad && ctx->digits != 0) { 283 ctx->pad = true; 284 do { 285 RETERR(base32_decode_char(ctx, '=')); 286 } while (ctx->digits != 0); 287 } 288 if (ctx->digits != 0) { 289 return (ISC_R_BADBASE32); 290 } 291 return (ISC_R_SUCCESS); 292} 293 294static isc_result_t 295base32_tobuffer(isc_lex_t *lexer, const char base[], bool pad, 296 isc_buffer_t *target, int length) { 297 unsigned int before, after; 298 base32_decode_ctx_t ctx; 299 isc_textregion_t *tr; 300 isc_token_t token; 301 bool eol; 302 303 REQUIRE(length >= -2); 304 305 base32_decode_init(&ctx, length, base, pad, target); 306 307 before = isc_buffer_usedlength(target); 308 while (!ctx.seen_end && (ctx.length != 0)) { 309 unsigned int i; 310 311 if (length > 0) { 312 eol = false; 313 } else { 314 eol = true; 315 } 316 RETERR(isc_lex_getmastertoken(lexer, &token, 317 isc_tokentype_string, eol)); 318 if (token.type != isc_tokentype_string) { 319 break; 320 } 321 tr = &token.value.as_textregion; 322 for (i = 0; i < tr->length; i++) { 323 RETERR(base32_decode_char(&ctx, tr->base[i])); 324 } 325 } 326 after = isc_buffer_usedlength(target); 327 if (ctx.length < 0 && !ctx.seen_end) { 328 isc_lex_ungettoken(lexer, &token); 329 } 330 RETERR(base32_decode_finish(&ctx)); 331 if (length == -2 && before == after) { 332 return (ISC_R_UNEXPECTEDEND); 333 } 334 return (ISC_R_SUCCESS); 335} 336 337isc_result_t 338isc_base32_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) { 339 return (base32_tobuffer(lexer, base32, true, target, length)); 340} 341 342isc_result_t 343isc_base32hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) { 344 return (base32_tobuffer(lexer, base32hex, true, target, length)); 345} 346 347isc_result_t 348isc_base32hexnp_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) { 349 return (base32_tobuffer(lexer, base32hex, false, target, length)); 350} 351 352static isc_result_t 353base32_decodestring(const char *cstr, const char base[], bool pad, 354 isc_buffer_t *target) { 355 base32_decode_ctx_t ctx; 356 357 base32_decode_init(&ctx, -1, base, pad, target); 358 for (;;) { 359 int c = *cstr++; 360 if (c == '\0') { 361 break; 362 } 363 if (c == ' ' || c == '\t' || c == '\n' || c == '\r') { 364 continue; 365 } 366 RETERR(base32_decode_char(&ctx, c)); 367 } 368 RETERR(base32_decode_finish(&ctx)); 369 return (ISC_R_SUCCESS); 370} 371 372isc_result_t 373isc_base32_decodestring(const char *cstr, isc_buffer_t *target) { 374 return (base32_decodestring(cstr, base32, true, target)); 375} 376 377isc_result_t 378isc_base32hex_decodestring(const char *cstr, isc_buffer_t *target) { 379 return (base32_decodestring(cstr, base32hex, true, target)); 380} 381 382isc_result_t 383isc_base32hexnp_decodestring(const char *cstr, isc_buffer_t *target) { 384 return (base32_decodestring(cstr, base32hex, false, target)); 385} 386 387static isc_result_t 388base32_decoderegion(isc_region_t *source, const char base[], bool pad, 389 isc_buffer_t *target) { 390 base32_decode_ctx_t ctx; 391 392 base32_decode_init(&ctx, -1, base, pad, target); 393 while (source->length != 0) { 394 int c = *source->base; 395 RETERR(base32_decode_char(&ctx, c)); 396 isc_region_consume(source, 1); 397 } 398 RETERR(base32_decode_finish(&ctx)); 399 return (ISC_R_SUCCESS); 400} 401 402isc_result_t 403isc_base32_decoderegion(isc_region_t *source, isc_buffer_t *target) { 404 return (base32_decoderegion(source, base32, true, target)); 405} 406 407isc_result_t 408isc_base32hex_decoderegion(isc_region_t *source, isc_buffer_t *target) { 409 return (base32_decoderegion(source, base32hex, true, target)); 410} 411 412isc_result_t 413isc_base32hexnp_decoderegion(isc_region_t *source, isc_buffer_t *target) { 414 return (base32_decoderegion(source, base32hex, false, target)); 415} 416 417static isc_result_t 418str_totext(const char *source, isc_buffer_t *target) { 419 unsigned int l; 420 isc_region_t region; 421 422 isc_buffer_availableregion(target, ®ion); 423 l = strlen(source); 424 425 if (l > region.length) { 426 return (ISC_R_NOSPACE); 427 } 428 429 memmove(region.base, source, l); 430 isc_buffer_add(target, l); 431 return (ISC_R_SUCCESS); 432} 433 434static isc_result_t 435mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) { 436 isc_region_t tr; 437 438 isc_buffer_availableregion(target, &tr); 439 if (length > tr.length) { 440 return (ISC_R_NOSPACE); 441 } 442 memmove(tr.base, base, length); 443 isc_buffer_add(target, length); 444 return (ISC_R_SUCCESS); 445} 446