270 lines
6.4 KiB
C
270 lines
6.4 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* SPDX-License-Identifier: MPL-2.0
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, you can obtain one at https://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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/*! \file */
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#include <stdbool.h>
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#include <isc/base64.h>
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#include <isc/buffer.h>
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#include <isc/lex.h>
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#include <isc/string.h>
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#include <isc/util.h>
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#define RETERR(x) \
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do { \
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isc_result_t _r = (x); \
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if (_r != ISC_R_SUCCESS) \
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return ((_r)); \
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} while (0)
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/*@{*/
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/*!
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* These static functions are also present in lib/dns/rdata.c. I'm not
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* sure where they should go. -- bwelling
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*/
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static isc_result_t
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str_totext(const char *source, isc_buffer_t *target);
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static isc_result_t
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mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length);
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static const char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvw"
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"xyz0123456789+/=";
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/*@}*/
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isc_result_t
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isc_base64_totext(isc_region_t *source, int wordlength, const char *wordbreak,
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isc_buffer_t *target) {
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char buf[5];
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unsigned int loops = 0;
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if (wordlength < 4) {
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wordlength = 4;
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}
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memset(buf, 0, sizeof(buf));
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while (source->length > 2) {
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buf[0] = base64[(source->base[0] >> 2) & 0x3f];
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buf[1] = base64[((source->base[0] << 4) & 0x30) |
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((source->base[1] >> 4) & 0x0f)];
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buf[2] = base64[((source->base[1] << 2) & 0x3c) |
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((source->base[2] >> 6) & 0x03)];
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buf[3] = base64[source->base[2] & 0x3f];
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RETERR(str_totext(buf, target));
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isc_region_consume(source, 3);
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loops++;
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if (source->length != 0 && (int)((loops + 1) * 4) >= wordlength)
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{
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loops = 0;
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RETERR(str_totext(wordbreak, target));
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}
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}
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if (source->length == 2) {
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buf[0] = base64[(source->base[0] >> 2) & 0x3f];
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buf[1] = base64[((source->base[0] << 4) & 0x30) |
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((source->base[1] >> 4) & 0x0f)];
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buf[2] = base64[((source->base[1] << 2) & 0x3c)];
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buf[3] = '=';
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RETERR(str_totext(buf, target));
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isc_region_consume(source, 2);
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} else if (source->length == 1) {
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buf[0] = base64[(source->base[0] >> 2) & 0x3f];
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buf[1] = base64[((source->base[0] << 4) & 0x30)];
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buf[2] = buf[3] = '=';
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RETERR(str_totext(buf, target));
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isc_region_consume(source, 1);
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}
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return ISC_R_SUCCESS;
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}
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/*%
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* State of a base64 decoding process in progress.
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*/
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typedef struct {
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int length; /*%< Desired length of binary data or -1 */
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isc_buffer_t *target; /*%< Buffer for resulting binary data */
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int digits; /*%< Number of buffered base64 digits */
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bool seen_end; /*%< True if "=" end marker seen */
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int val[4];
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} base64_decode_ctx_t;
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static void
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base64_decode_init(base64_decode_ctx_t *ctx, int length, isc_buffer_t *target) {
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ctx->digits = 0;
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ctx->seen_end = false;
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ctx->length = length;
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ctx->target = target;
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}
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static isc_result_t
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base64_decode_char(base64_decode_ctx_t *ctx, int c) {
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const char *s;
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if (ctx->seen_end) {
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return ISC_R_BADBASE64;
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}
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if ((s = strchr(base64, c)) == NULL) {
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return ISC_R_BADBASE64;
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}
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ctx->val[ctx->digits++] = (int)(s - base64);
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if (ctx->digits == 4) {
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int n;
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unsigned char buf[3];
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if (ctx->val[0] == 64 || ctx->val[1] == 64) {
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return ISC_R_BADBASE64;
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}
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if (ctx->val[2] == 64 && ctx->val[3] != 64) {
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return ISC_R_BADBASE64;
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}
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/*
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* Check that bits that should be zero are.
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*/
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if (ctx->val[2] == 64 && (ctx->val[1] & 0xf) != 0) {
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return ISC_R_BADBASE64;
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}
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/*
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* We don't need to test for ctx->val[2] != 64 as
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* the bottom two bits of 64 are zero.
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*/
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if (ctx->val[3] == 64 && (ctx->val[2] & 0x3) != 0) {
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return ISC_R_BADBASE64;
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}
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n = (ctx->val[2] == 64) ? 1 : (ctx->val[3] == 64) ? 2 : 3;
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if (n != 3) {
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ctx->seen_end = true;
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if (ctx->val[2] == 64) {
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ctx->val[2] = 0;
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}
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if (ctx->val[3] == 64) {
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ctx->val[3] = 0;
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}
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}
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buf[0] = (ctx->val[0] << 2) | (ctx->val[1] >> 4);
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buf[1] = (ctx->val[1] << 4) | (ctx->val[2] >> 2);
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buf[2] = (ctx->val[2] << 6) | (ctx->val[3]);
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RETERR(mem_tobuffer(ctx->target, buf, n));
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if (ctx->length >= 0) {
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if (n > ctx->length) {
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return ISC_R_BADBASE64;
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} else {
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ctx->length -= n;
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}
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}
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ctx->digits = 0;
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}
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return ISC_R_SUCCESS;
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}
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static isc_result_t
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base64_decode_finish(base64_decode_ctx_t *ctx) {
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if (ctx->length > 0) {
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return ISC_R_UNEXPECTEDEND;
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}
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if (ctx->digits != 0) {
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return ISC_R_BADBASE64;
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}
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return ISC_R_SUCCESS;
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}
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isc_result_t
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isc_base64_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
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unsigned int before, after;
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base64_decode_ctx_t ctx;
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isc_textregion_t *tr;
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isc_token_t token;
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bool eol;
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REQUIRE(length >= -2);
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base64_decode_init(&ctx, length, target);
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before = isc_buffer_usedlength(target);
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while (!ctx.seen_end && (ctx.length != 0)) {
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unsigned int i;
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if (length > 0) {
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eol = false;
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} else {
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eol = true;
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}
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RETERR(isc_lex_getmastertoken(lexer, &token,
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isc_tokentype_string, eol));
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if (token.type != isc_tokentype_string) {
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break;
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}
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tr = &token.value.as_textregion;
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for (i = 0; i < tr->length; i++) {
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RETERR(base64_decode_char(&ctx, tr->base[i]));
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}
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}
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after = isc_buffer_usedlength(target);
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if (ctx.length < 0 && !ctx.seen_end) {
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isc_lex_ungettoken(lexer, &token);
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}
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RETERR(base64_decode_finish(&ctx));
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if (length == -2 && before == after) {
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return ISC_R_UNEXPECTEDEND;
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}
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return ISC_R_SUCCESS;
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}
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isc_result_t
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isc_base64_decodestring(const char *cstr, isc_buffer_t *target) {
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base64_decode_ctx_t ctx;
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base64_decode_init(&ctx, -1, target);
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for (;;) {
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int c = *cstr++;
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if (c == '\0') {
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break;
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}
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if (c == ' ' || c == '\t' || c == '\n' || c == '\r') {
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continue;
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}
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RETERR(base64_decode_char(&ctx, c));
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}
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RETERR(base64_decode_finish(&ctx));
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return ISC_R_SUCCESS;
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}
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static isc_result_t
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str_totext(const char *source, isc_buffer_t *target) {
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unsigned int l;
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isc_region_t region;
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isc_buffer_availableregion(target, ®ion);
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l = strlen(source);
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if (l > region.length) {
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return ISC_R_NOSPACE;
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}
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memmove(region.base, source, l);
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isc_buffer_add(target, l);
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return ISC_R_SUCCESS;
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}
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static isc_result_t
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mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {
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isc_region_t tr;
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isc_buffer_availableregion(target, &tr);
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if (length > tr.length) {
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return ISC_R_NOSPACE;
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}
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memmove(tr.base, base, length);
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isc_buffer_add(target, length);
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return ISC_R_SUCCESS;
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}
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