mirror of
https://gitlab.com/gnuwget/wget2.git
synced 2025-08-20 16:24:12 +00:00
241b9a1d2d
* include/wget/wget.h: Declare both function as pure * libwget/base64.c: Add both functions incl. documentation, (wget_base64_decode_alloc): Remove hard-coded calculation, (wget_base64_encode_alloc): Likewise. * libwget/tls_session.c (_tls_session_save): Use wget_base64_get_encoded_length() instead hard-coded calculation * fuzz/libwget_base64_fuzzer.c: Avoid both functions to be optimized out
331 lines
9.1 KiB
C
331 lines
9.1 KiB
C
/*
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* Copyright(c) 2012 Tim Ruehsen
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* Copyright(c) 2015-2018 Free Software Foundation, Inc.
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*
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* This file is part of libwget.
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*
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* Libwget is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Libwget is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with libwget. If not, see <https://www.gnu.org/licenses/>.
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*
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*
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* base64 conversion routines
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*
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* Changelog
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* 21.12.2012 Tim Ruehsen created
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*
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*/
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#include <config.h>
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#include <stddef.h>
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#include <stdarg.h>
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#include <wget.h>
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#include "private.h"
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/**
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* \file
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* \brief Base64 functions
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* \defgroup libwget-base64 Base64 functions
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* @{
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*
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* This is a collection base64 encoding/decoding functions used in Wget2.
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*/
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static const unsigned char base64_2_bin[256] = {
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 62, 0, 63,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, 0, 0, 0,
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0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 63,
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0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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static bool G_GNUC_WGET_CONST _isbase64(char c)
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{
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// isalnum(c) does not work for all locales
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return !!base64_2_bin[(unsigned char) c];
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// return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '+' || c == '/' || c == '-' || c == '_';
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}
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/**
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* \param[in] src String to be checked
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* \return 1 if \p src is a base64 string, 0 otherwise
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*
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* Checks whether \p src is a base64 string.
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* Returns 0 if \p src is NULL.
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*/
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bool wget_base64_is_string(const char *src)
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{
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if (src) {
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while (_isbase64(*src)) src++;
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if (!*src || (*src == '=' && src[1]) || (*src == '=' && src[1] == '=' && src[2]))
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return 1;
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}
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return 0;
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}
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/**
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* \param[out] dst Output buffer
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* \param[in] src Base64 string to be decoded
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* \param[in] n Length of \p src
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* \return Number of bytes written into \p dst
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*
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* Decodes \p n bytes of the base64 string \p src.
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* The decoded bytes are written into \p dst and are 0-terminated.
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*
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* The size of \p dst has to be at minimum ((\p n + 3) / 4) * 3 + 1 bytes.
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*/
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size_t wget_base64_decode(char *dst, const char *src, size_t n)
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{
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const unsigned char *usrc = (const unsigned char *)src;
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char *old = dst;
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int extra;
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// trim '=' at the end
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while (n > 0 && !_isbase64(usrc[n - 1]))
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n--;
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extra = n & 3;
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for (n /= 4; n > 0; n--, usrc += 4) {
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*dst++ = (char)(base64_2_bin[usrc[0]] << 2 | base64_2_bin[usrc[1]] >> 4);
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*dst++ = (char)((base64_2_bin[usrc[1]]&0x0F) << 4 | base64_2_bin[usrc[2]] >> 2);
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*dst++ = (char)((base64_2_bin[usrc[2]]&0x03) << 6 | base64_2_bin[usrc[3]]);
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}
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switch (extra) {
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case 1:
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// this should not happen
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*dst++ = (char) (base64_2_bin[usrc[0]] << 2);
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break;
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case 2:
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*dst++ = (char)(base64_2_bin[usrc[0]] << 2 | base64_2_bin[usrc[1]] >> 4);
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*dst = (char)((base64_2_bin[usrc[1]]&0x0F) << 4);
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if (*dst) dst++;
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break;
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case 3:
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*dst++ = (char)(base64_2_bin[usrc[0]] << 2 | base64_2_bin[usrc[1]] >> 4);
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*dst++ = (char)((base64_2_bin[usrc[1]]&0x0F) << 4 | base64_2_bin[usrc[2]] >> 2);
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*dst = (char)((base64_2_bin[usrc[2]]&0x03) << 6);
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if (*dst) dst++;
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break;
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default: // 0: ignore
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break;
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}
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*dst = 0;
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return (size_t) (dst - old);
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}
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/**
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* \param[in] src Base64 string to be decoded
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* \param[in] n Length of \p src
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* \param[out] outlen Length of returned string, may be NULL.
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* \return Decoded bytes, zero terminated
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*
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* Decodes \p n bytes of the base64 string \p src.
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* The decoded bytes are returned in an allocated buffer.
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*
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* You should free() the returned string when not needed any more.
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*/
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char *wget_base64_decode_alloc(const char *src, size_t n, size_t *outlen)
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{
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char *dst = xmalloc(wget_base64_get_decoded_length(n));
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size_t _outlen = wget_base64_decode(dst, src, n);
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if (outlen)
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*outlen = _outlen;
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return dst;
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}
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#define WGET_BASE64_URLENCODE 1
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static size_t _wget_base64_encode(char *dst, const char *src, size_t n, int flags)
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{
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static const char base64unsafe[64] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static const char base64urlsafe[64] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
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const char *base64 = (flags & WGET_BASE64_URLENCODE) ? base64urlsafe : base64unsafe;
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const unsigned char *usrc = (const unsigned char *)src;
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char *start = dst;
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int extra = n % 3;
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// convert line by line
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for (n /= 3; n > 0; n--, usrc += 3) {
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*dst++ = base64[usrc[0] >> 2];
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*dst++ = base64[((usrc[0]&3) << 4) | (usrc[1] >> 4)];
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*dst++ = base64[((usrc[1]&15) << 2) | (usrc[2] >> 6)];
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*dst++ = base64[usrc[2]&0x3f];
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}
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// special case
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if (extra == 1) {
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*dst++ = base64[usrc[0] >> 2];
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*dst++ = base64[(usrc[0]&3) << 4];
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*dst++ = '=';
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*dst++ = '=';
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} else if (extra == 2) {
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*dst++ = base64[usrc[0] >> 2];
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*dst++ = base64[((usrc[0]&3) << 4) | (usrc[1] >> 4)];
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*dst++ = base64[((usrc[1]&15) << 2)];
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*dst++ = '=';
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}
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*dst = 0;
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return (size_t) (dst - start);
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}
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/**
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* \param[out] dst Base64 output string
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* \param[in] src Input buffer
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* \param[in] n Number of bytes to be encoded
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* \return Length of output string \p dst
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*
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* Encodes \p n bytes from \p src into a base64 string.
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* The encoded string is written into \p dst (0-terminated).
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*
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* The length of \p dst has to be at minimum ((\p n + 2) / 3) * 4 + 1 bytes.
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*/
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size_t wget_base64_encode(char *dst, const char *src, size_t n)
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{
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return _wget_base64_encode(dst, src, n, 0);
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}
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/**
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* \param[out] dst Base64 output string (URL and filename safe)
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* \param[in] src Input buffer
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* \param[in] n Number of bytes to be encoded
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* \return Length of output string \p dst
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*
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* Encodes \p n bytes from \p src into a base64 URL and filename safe string (see RFC 4648, 5.).
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* The encoded string is written into \p dst (0-terminated).
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*
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* The length of \p dst has to be at minimum ((\p n + 2) / 3) * 4 + 1 bytes.
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*/
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size_t wget_base64_urlencode(char *dst, const char *src, size_t n)
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{
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return _wget_base64_encode(dst, src, n, WGET_BASE64_URLENCODE);
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}
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/**
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* \param[in] src Input buffer
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* \param[in] n Number of bytes to be encoded
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* \return Base64 encoded string
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*
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* Encodes \p n bytes from input buffer \p src.
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* The encoded string is returned in an allocated buffer.
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*
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* You should free() the returned string when not needed any more.
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*/
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char *wget_base64_encode_alloc(const char *src, size_t n)
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{
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char *dst = xmalloc(wget_base64_get_encoded_length(n));
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wget_base64_encode(dst, src, n);
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return dst;
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}
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/**
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* \param[in] fmt Printf-like format string
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* \param[in] args Argument list
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* \return Base64 encoded string
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*
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* Encodes the string constructed by \p fmt and \p args.
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* The encoded string is returned in an allocated buffer.
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*
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* You should free() the returned string when not needed any more.
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*/
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char *wget_base64_encode_vprintf_alloc(const char *fmt, va_list args)
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{
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char *data = NULL;
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size_t n;
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n = wget_vasprintf(&data, fmt, args);
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if (data) {
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char *dst = wget_base64_encode_alloc(data, n);
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xfree(data);
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return dst;
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}
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return NULL;
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}
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/**
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* \param[in] fmt Printf-like format string
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* \param[in] ... Argument list
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* \return Base64 encoded string
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*
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* Encodes the string constructed by \p fmt and the arguments.
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* The encoded string is returned in an allocated buffer.
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*
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* You should free() the returned string when not needed any more.
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*/
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char *wget_base64_encode_printf_alloc(const char *fmt, ...)
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{
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char *dst;
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va_list args;
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va_start(args, fmt);
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dst = wget_base64_encode_vprintf_alloc(fmt, args);
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va_end(args);
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return dst;
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}
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/**
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* \fn static inline size_t wget_base64_get_decoded_length(size_t len)
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* \param[in] len Length of base64 sequence
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* \return Number of decoded bytes plus one (for 0-byte termination)
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*
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* Calculate the number of bytes needed for decoding a base64 sequence with length \p len.
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*/
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size_t wget_base64_get_decoded_length(size_t len)
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{
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return ((len + 3) / 4) * 3 + 1;
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}
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/**
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* \fn static inline size_t wget_base64_get_encoded_length(size_t len)
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* \param[in] len Number of (un-encoded) bytes
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* \return Length of base64 encoding plus one (for 0-byte termination)
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*
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* Calculate the number of bytes needed for base64 encoding a byte sequence with length \p len,
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* including the padding and 0-termination bytes.
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*/
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size_t wget_base64_get_encoded_length(size_t len)
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{
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return ((len + 2) / 3) * 4 + 1;
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}
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/**@}*/
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