/* $NetBSD: base64.c,v 1.1.2.2 2024/02/24 13:07:19 martin 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 #include #include #include #include #include #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 base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvw" "xyz0123456789+/="; /*@}*/ isc_result_t isc_base64_totext(isc_region_t *source, int wordlength, const char *wordbreak, isc_buffer_t *target) { char buf[5]; unsigned int loops = 0; if (wordlength < 4) { wordlength = 4; } memset(buf, 0, sizeof(buf)); while (source->length > 2) { buf[0] = base64[(source->base[0] >> 2) & 0x3f]; buf[1] = base64[((source->base[0] << 4) & 0x30) | ((source->base[1] >> 4) & 0x0f)]; buf[2] = base64[((source->base[1] << 2) & 0x3c) | ((source->base[2] >> 6) & 0x03)]; buf[3] = base64[source->base[2] & 0x3f]; RETERR(str_totext(buf, target)); isc_region_consume(source, 3); loops++; if (source->length != 0 && (int)((loops + 1) * 4) >= wordlength) { loops = 0; RETERR(str_totext(wordbreak, target)); } } if (source->length == 2) { buf[0] = base64[(source->base[0] >> 2) & 0x3f]; buf[1] = base64[((source->base[0] << 4) & 0x30) | ((source->base[1] >> 4) & 0x0f)]; buf[2] = base64[((source->base[1] << 2) & 0x3c)]; buf[3] = '='; RETERR(str_totext(buf, target)); isc_region_consume(source, 2); } else if (source->length == 1) { buf[0] = base64[(source->base[0] >> 2) & 0x3f]; buf[1] = base64[((source->base[0] << 4) & 0x30)]; buf[2] = buf[3] = '='; RETERR(str_totext(buf, target)); isc_region_consume(source, 1); } return (ISC_R_SUCCESS); } /*% * State of a base64 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 base64 digits */ bool seen_end; /*%< True if "=" end marker seen */ int val[4]; } base64_decode_ctx_t; static void base64_decode_init(base64_decode_ctx_t *ctx, int length, isc_buffer_t *target) { ctx->digits = 0; ctx->seen_end = false; ctx->length = length; ctx->target = target; } static isc_result_t base64_decode_char(base64_decode_ctx_t *ctx, int c) { const char *s; if (ctx->seen_end) { return (ISC_R_BADBASE64); } if ((s = strchr(base64, c)) == NULL) { return (ISC_R_BADBASE64); } ctx->val[ctx->digits++] = (int)(s - base64); if (ctx->digits == 4) { int n; unsigned char buf[3]; if (ctx->val[0] == 64 || ctx->val[1] == 64) { return (ISC_R_BADBASE64); } if (ctx->val[2] == 64 && ctx->val[3] != 64) { return (ISC_R_BADBASE64); } /* * Check that bits that should be zero are. */ if (ctx->val[2] == 64 && (ctx->val[1] & 0xf) != 0) { return (ISC_R_BADBASE64); } /* * We don't need to test for ctx->val[2] != 64 as * the bottom two bits of 64 are zero. */ if (ctx->val[3] == 64 && (ctx->val[2] & 0x3) != 0) { return (ISC_R_BADBASE64); } n = (ctx->val[2] == 64) ? 1 : (ctx->val[3] == 64) ? 2 : 3; if (n != 3) { ctx->seen_end = true; if (ctx->val[2] == 64) { ctx->val[2] = 0; } if (ctx->val[3] == 64) { ctx->val[3] = 0; } } buf[0] = (ctx->val[0] << 2) | (ctx->val[1] >> 4); buf[1] = (ctx->val[1] << 4) | (ctx->val[2] >> 2); buf[2] = (ctx->val[2] << 6) | (ctx->val[3]); RETERR(mem_tobuffer(ctx->target, buf, n)); if (ctx->length >= 0) { if (n > ctx->length) { return (ISC_R_BADBASE64); } else { ctx->length -= n; } } ctx->digits = 0; } return (ISC_R_SUCCESS); } static isc_result_t base64_decode_finish(base64_decode_ctx_t *ctx) { if (ctx->length > 0) { return (ISC_R_UNEXPECTEDEND); } if (ctx->digits != 0) { return (ISC_R_BADBASE64); } return (ISC_R_SUCCESS); } isc_result_t isc_base64_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) { unsigned int before, after; base64_decode_ctx_t ctx; isc_textregion_t *tr; isc_token_t token; bool eol; REQUIRE(length >= -2); base64_decode_init(&ctx, length, 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(base64_decode_char(&ctx, tr->base[i])); } } after = isc_buffer_usedlength(target); if (ctx.length < 0 && !ctx.seen_end) { isc_lex_ungettoken(lexer, &token); } RETERR(base64_decode_finish(&ctx)); if (length == -2 && before == after) { return (ISC_R_UNEXPECTEDEND); } return (ISC_R_SUCCESS); } isc_result_t isc_base64_decodestring(const char *cstr, isc_buffer_t *target) { base64_decode_ctx_t ctx; base64_decode_init(&ctx, -1, target); for (;;) { int c = *cstr++; if (c == '\0') { break; } if (c == ' ' || c == '\t' || c == '\n' || c == '\r') { continue; } RETERR(base64_decode_char(&ctx, c)); } RETERR(base64_decode_finish(&ctx)); return (ISC_R_SUCCESS); } 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); }