/* $NetBSD: base32.c,v 1.1 2024/02/18 20:57:48 christos Exp $ */ /* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /*! \file */ #include <stdbool.h> #include <isc/base32.h> #include <isc/buffer.h> #include <isc/lex.h> #include <isc/region.h> #include <isc/string.h> #include <isc/util.h> #define RETERR(x) \ do { \ isc_result_t _r = (x); \ if (_r != ISC_R_SUCCESS) \ return ((_r)); \ } while (0) /*@{*/ /*! * These static functions are also present in lib/dns/rdata.c. I'm not * sure where they should go. -- bwelling */ static isc_result_t str_totext(const char *source, isc_buffer_t *target); static isc_result_t mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length); /*@}*/ static const char base32[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=" "abcdefghijklmnopqrstuvwxyz234567"; static const char base32hex[] = "0123456789ABCDEFGHIJKLMNOPQRSTUV=" "0123456789abcdefghijklmnopqrstuv"; static isc_result_t base32_totext(isc_region_t *source, int wordlength, const char *wordbreak, isc_buffer_t *target, const char base[], char pad) { char buf[9]; unsigned int loops = 0; if (wordlength >= 0 && wordlength < 8) { wordlength = 8; } memset(buf, 0, sizeof(buf)); while (source->length > 0) { buf[0] = base[((source->base[0] >> 3) & 0x1f)]; /* 5 + */ if (source->length == 1) { buf[1] = base[(source->base[0] << 2) & 0x1c]; buf[2] = buf[3] = buf[4] = pad; buf[5] = buf[6] = buf[7] = pad; RETERR(str_totext(buf, target)); break; } buf[1] = base[((source->base[0] << 2) & 0x1c) | /* 3 = 8 */ ((source->base[1] >> 6) & 0x03)]; /* 2 + */ buf[2] = base[((source->base[1] >> 1) & 0x1f)]; /* 5 + */ if (source->length == 2) { buf[3] = base[(source->base[1] << 4) & 0x10]; buf[4] = buf[5] = buf[6] = buf[7] = pad; RETERR(str_totext(buf, target)); break; } buf[3] = base[((source->base[1] << 4) & 0x10) | /* 1 = 8 */ ((source->base[2] >> 4) & 0x0f)]; /* 4 + */ if (source->length == 3) { buf[4] = base[(source->base[2] << 1) & 0x1e]; buf[5] = buf[6] = buf[7] = pad; RETERR(str_totext(buf, target)); break; } buf[4] = base[((source->base[2] << 1) & 0x1e) | /* 4 = 8 */ ((source->base[3] >> 7) & 0x01)]; /* 1 + */ buf[5] = base[((source->base[3] >> 2) & 0x1f)]; /* 5 + */ if (source->length == 4) { buf[6] = base[(source->base[3] << 3) & 0x18]; buf[7] = pad; RETERR(str_totext(buf, target)); break; } buf[6] = base[((source->base[3] << 3) & 0x18) | /* 2 = 8 */ ((source->base[4] >> 5) & 0x07)]; /* 3 + */ buf[7] = base[source->base[4] & 0x1f]; /* 5 = 8 */ RETERR(str_totext(buf, target)); isc_region_consume(source, 5); loops++; if (source->length != 0 && wordlength >= 0 && (int)((loops + 1) * 8) >= wordlength) { loops = 0; RETERR(str_totext(wordbreak, target)); } } if (source->length > 0) { isc_region_consume(source, source->length); } return (ISC_R_SUCCESS); } isc_result_t isc_base32_totext(isc_region_t *source, int wordlength, const char *wordbreak, isc_buffer_t *target) { return (base32_totext(source, wordlength, wordbreak, target, base32, '=')); } isc_result_t isc_base32hex_totext(isc_region_t *source, int wordlength, const char *wordbreak, isc_buffer_t *target) { return (base32_totext(source, wordlength, wordbreak, target, base32hex, '=')); } isc_result_t isc_base32hexnp_totext(isc_region_t *source, int wordlength, const char *wordbreak, isc_buffer_t *target) { return (base32_totext(source, wordlength, wordbreak, target, base32hex, 0)); } /*% * State of a base32 decoding process in progress. */ typedef struct { int length; /*%< Desired length of binary data or -1 */ isc_buffer_t *target; /*%< Buffer for resulting binary data */ int digits; /*%< Number of buffered base32 digits */ bool seen_end; /*%< True if "=" end marker seen */ int val[8]; const char *base; /*%< Which encoding we are using */ int seen_32; /*%< Number of significant bytes if non * zero */ bool pad; /*%< Expect padding */ } base32_decode_ctx_t; static void base32_decode_init(base32_decode_ctx_t *ctx, int length, const char base[], bool pad, isc_buffer_t *target) { ctx->digits = 0; ctx->seen_end = false; ctx->seen_32 = 0; ctx->length = length; ctx->target = target; ctx->base = base; ctx->pad = pad; } static isc_result_t base32_decode_char(base32_decode_ctx_t *ctx, int c) { const char *s; unsigned int last; if (ctx->seen_end) { return (ISC_R_BADBASE32); } if ((s = strchr(ctx->base, c)) == NULL) { return (ISC_R_BADBASE32); } last = (unsigned int)(s - ctx->base); /* * Handle lower case. */ if (last > 32) { last -= 33; } /* * Check that padding is contiguous. */ if (last != 32 && ctx->seen_32 != 0) { return (ISC_R_BADBASE32); } /* * If padding is not permitted flag padding as a error. */ if (last == 32 && !ctx->pad) { return (ISC_R_BADBASE32); } /* * Check that padding starts at the right place and that * bits that should be zero are. * Record how many significant bytes in answer (seen_32). */ if (last == 32 && ctx->seen_32 == 0) { switch (ctx->digits) { case 0: case 1: return (ISC_R_BADBASE32); case 2: if ((ctx->val[1] & 0x03) != 0) { return (ISC_R_BADBASE32); } ctx->seen_32 = 1; break; case 3: return (ISC_R_BADBASE32); case 4: if ((ctx->val[3] & 0x0f) != 0) { return (ISC_R_BADBASE32); } ctx->seen_32 = 2; break; case 5: if ((ctx->val[4] & 0x01) != 0) { return (ISC_R_BADBASE32); } ctx->seen_32 = 3; break; case 6: return (ISC_R_BADBASE32); case 7: if ((ctx->val[6] & 0x07) != 0) { return (ISC_R_BADBASE32); } ctx->seen_32 = 4; break; } } /* * Zero fill pad values. */ ctx->val[ctx->digits++] = (last == 32) ? 0 : last; if (ctx->digits == 8) { int n = 5; unsigned char buf[5]; if (ctx->seen_32 != 0) { ctx->seen_end = true; n = ctx->seen_32; } buf[0] = (ctx->val[0] << 3) | (ctx->val[1] >> 2); buf[1] = (ctx->val[1] << 6) | (ctx->val[2] << 1) | (ctx->val[3] >> 4); buf[2] = (ctx->val[3] << 4) | (ctx->val[4] >> 1); buf[3] = (ctx->val[4] << 7) | (ctx->val[5] << 2) | (ctx->val[6] >> 3); buf[4] = (ctx->val[6] << 5) | (ctx->val[7]); RETERR(mem_tobuffer(ctx->target, buf, n)); if (ctx->length >= 0) { if (n > ctx->length) { return (ISC_R_BADBASE32); } else { ctx->length -= n; } } ctx->digits = 0; } return (ISC_R_SUCCESS); } static isc_result_t base32_decode_finish(base32_decode_ctx_t *ctx) { if (ctx->length > 0) { return (ISC_R_UNEXPECTEDEND); } /* * Add missing padding if required. */ if (!ctx->pad && ctx->digits != 0) { ctx->pad = true; do { RETERR(base32_decode_char(ctx, '=')); } while (ctx->digits != 0); } if (ctx->digits != 0) { return (ISC_R_BADBASE32); } return (ISC_R_SUCCESS); } static isc_result_t base32_tobuffer(isc_lex_t *lexer, const char base[], bool pad, isc_buffer_t *target, int length) { unsigned int before, after; base32_decode_ctx_t ctx; isc_textregion_t *tr; isc_token_t token; bool eol; REQUIRE(length >= -2); base32_decode_init(&ctx, length, base, pad, target); before = isc_buffer_usedlength(target); while (!ctx.seen_end && (ctx.length != 0)) { unsigned int i; if (length > 0) { eol = false; } else { eol = true; } RETERR(isc_lex_getmastertoken(lexer, &token, isc_tokentype_string, eol)); if (token.type != isc_tokentype_string) { break; } tr = &token.value.as_textregion; for (i = 0; i < tr->length; i++) { RETERR(base32_decode_char(&ctx, tr->base[i])); } } after = isc_buffer_usedlength(target); if (ctx.length < 0 && !ctx.seen_end) { isc_lex_ungettoken(lexer, &token); } RETERR(base32_decode_finish(&ctx)); if (length == -2 && before == after) { return (ISC_R_UNEXPECTEDEND); } return (ISC_R_SUCCESS); } isc_result_t isc_base32_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) { return (base32_tobuffer(lexer, base32, true, target, length)); } isc_result_t isc_base32hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) { return (base32_tobuffer(lexer, base32hex, true, target, length)); } isc_result_t isc_base32hexnp_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) { return (base32_tobuffer(lexer, base32hex, false, target, length)); } static isc_result_t base32_decodestring(const char *cstr, const char base[], bool pad, isc_buffer_t *target) { base32_decode_ctx_t ctx; base32_decode_init(&ctx, -1, base, pad, target); for (;;) { int c = *cstr++; if (c == '\0') { break; } if (c == ' ' || c == '\t' || c == '\n' || c == '\r') { continue; } RETERR(base32_decode_char(&ctx, c)); } RETERR(base32_decode_finish(&ctx)); return (ISC_R_SUCCESS); } isc_result_t isc_base32_decodestring(const char *cstr, isc_buffer_t *target) { return (base32_decodestring(cstr, base32, true, target)); } isc_result_t isc_base32hex_decodestring(const char *cstr, isc_buffer_t *target) { return (base32_decodestring(cstr, base32hex, true, target)); } isc_result_t isc_base32hexnp_decodestring(const char *cstr, isc_buffer_t *target) { return (base32_decodestring(cstr, base32hex, false, target)); } static isc_result_t base32_decoderegion(isc_region_t *source, const char base[], bool pad, isc_buffer_t *target) { base32_decode_ctx_t ctx; base32_decode_init(&ctx, -1, base, pad, target); while (source->length != 0) { int c = *source->base; RETERR(base32_decode_char(&ctx, c)); isc_region_consume(source, 1); } RETERR(base32_decode_finish(&ctx)); return (ISC_R_SUCCESS); } isc_result_t isc_base32_decoderegion(isc_region_t *source, isc_buffer_t *target) { return (base32_decoderegion(source, base32, true, target)); } isc_result_t isc_base32hex_decoderegion(isc_region_t *source, isc_buffer_t *target) { return (base32_decoderegion(source, base32hex, true, target)); } isc_result_t isc_base32hexnp_decoderegion(isc_region_t *source, isc_buffer_t *target) { return (base32_decoderegion(source, base32hex, false, target)); } static isc_result_t str_totext(const char *source, isc_buffer_t *target) { unsigned int l; isc_region_t region; isc_buffer_availableregion(target, ®ion); l = strlen(source); if (l > region.length) { return (ISC_R_NOSPACE); } memmove(region.base, source, l); isc_buffer_add(target, l); return (ISC_R_SUCCESS); } static isc_result_t mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) { isc_region_t tr; isc_buffer_availableregion(target, &tr); if (length > tr.length) { return (ISC_R_NOSPACE); } memmove(tr.base, base, length); isc_buffer_add(target, length); return (ISC_R_SUCCESS); }