/* Copyright (c) 2006-2007, Philip Busch * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * - Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /** * @file * Base64 implementation. * @ingroup base64 */ #include #include #include #include "base64.h" #define XX 100 /** @var base64_list * A 64 character alphabet. * * A 64-character subset of International Alphabet IA5, enabling * 6 bits to be represented per printable character. (The proposed * subset of characters is represented identically in IA5 and ASCII.) * The character "=" signifies a special processing function used for * padding within the printable encoding procedure. * * \verbatim Value Encoding Value Encoding Value Encoding Value Encoding 0 A 17 R 34 i 51 z 1 B 18 S 35 j 52 0 2 C 19 T 36 k 53 1 3 D 20 U 37 l 54 2 4 E 21 V 38 m 55 3 5 F 22 W 39 n 56 4 6 G 23 X 40 o 57 5 7 H 24 Y 41 p 58 6 8 I 25 Z 42 q 59 7 9 J 26 a 43 r 60 8 10 K 27 b 44 s 61 9 11 L 28 c 45 t 62 + 12 M 29 d 46 u 63 / 13 N 30 e 47 v 14 O 31 f 48 w (pad) = 15 P 32 g 49 x 16 Q 33 h 50 y \endverbatim */ static const char base64_list[] = \ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; static const int base64_index[256] = { XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,62, XX,XX,XX,63, 52,53,54,55, 56,57,58,59, 60,61,XX,XX, XX,XX,XX,XX, XX, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11,12,13,14, 15,16,17,18, 19,20,21,22, 23,24,25,XX, XX,XX,XX,XX, XX,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40, 41,42,43,44, 45,46,47,48, 49,50,51,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, }; /** Encode a minimal memory block. This function encodes a minimal memory area * of three bytes into a printable base64-format sequence of four bytes. * It is mainly used in more convenient functions, see below. * * @attention This function can't check if there's enough space at the memory * memory location pointed to by \c out, so be careful. * * @param out pointer to destination * @param in pointer to source * @param len input size in bytes (between 0 and 3) * @returns nothing * * @ingroup base64 */ void base64_encode_block(unsigned char out[4], const unsigned char in[3], int len) { out[0] = base64_list[ in[0] >> 2 ]; out[1] = base64_list[ ((in[0] & 0x03) << 4) | ((in[1] & 0xf0) >> 4) ]; out[2] = (unsigned char) (len > 1 ? base64_list[ ((in[1] & 0x0f) << 2) | ((in[2] & 0xc0) >> 6) ] : '='); out[3] = (unsigned char) (len > 2 ? base64_list[in[2] & 0x3f] : '='); } /** Decode a minimal memory block. This function decodes a minimal memory area * of four bytes into its decoded equivalent. It is mainly used in more * convenient functions, see below. * * @attention This function can't check if there's enough space at the memory * memory location pointed to by \c out, so be careful. * * @param out pointer to destination * @param in pointer to source * @returns -1 on error (illegal character) or the number of bytes decoded * * @ingroup base64 */ int base64_decode_block(unsigned char out[3], const unsigned char in[4]) { int i, numbytes = 3; char tmp[4]; for(i = 3; i >= 0; i--) { if(in[i] == '=') { tmp[i] = 0; numbytes = i - 1; } else { tmp[i] = base64_index[ (unsigned char)in[i] ]; } if(tmp[i] == XX) return(-1); } out[0] = (unsigned char) ( tmp[0] << 2 | tmp[1] >> 4); out[1] = (unsigned char) ( tmp[1] << 4 | tmp[2] >> 2); out[2] = (unsigned char) (((tmp[2] << 6) & 0xc0) | tmp[3]); return(numbytes); } /** Compute size of needed storage for encoding. This function computes the * \e exact size of a memory area needed to hold the result of an encoding * operation, not including the terminating null character. * * @param len input size * @returns output size * * @ingroup base64 */ size_t base64_encoded_size(size_t len) { return(((len + 2) / 3) * 4); } /** Compute size of needed storage for decoding. This function computes the * \e estimated size of a memory area needed to hold the result of a decoding * operation, not including the terminating null character. Note that this * function may return up to two bytes more due to the nature of Base64. * * @param len input size * @returns output size * * @ingroup base64 */ size_t base64_decoded_size(size_t len) { return((len / 4) * 3); } /** Encode an arbitrary size memory area. This function encodes the first * \c len bytes of the contents of the memory area pointed to by \c in and * stores the result in the memory area pointed to by \c out. The result will * be null-terminated. * * @attention This function can't check if there's enough space at the memory * memory location pointed to by \c out, so be careful. * * @param out pointer to destination * @param in pointer to source * @param len input size in bytes * @returns nothing * * @ingroup base64 */ void base64_encode_binary(char *out, const unsigned char *in, size_t len) { int size; size_t i = 0; while(i < len) { size = (len-i < 4) ? len-i : 4; base64_encode_block((unsigned char *)out, in, size); out += 4; in += 3; i += 3; } *out = '\0'; } /** Decode an arbitrary size memory area. This function decodes the * base64-string pointed to by \c in and stores the result in the memory area * pointed to by \c out. The result will \e not be null-terminated. * * @attention This function can't check if there's enough space at the memory * memory location pointed to by \c out, so be careful. * * @param out pointer to destination * @param in pointer to source * @returns -1 on error (illegal character) or the number of bytes decoded * * @ingroup base64 */ int base64_decode_binary(unsigned char *out, const char *in) { size_t len = strlen(in), i = 0; int numbytes = 0; while(i < len) { if((numbytes += base64_decode_block(out, (unsigned char *)in)) < 0) return(-1); out += 3; in += 4; i += 4; } return(numbytes); } /** Encode a string. This is a convenience function. It encodes the first * \c size bytes of the string pointed to by \c in, stores the null-terminated * result in a newly created memory area and returns a pointer to it. * * @attention After a call to base64_encode(), you have to free() the result * yourself. * * @param in pointer to string * @param size strlen * @returns NULL on error (not enough memory) or a pointer to the encoded result * * @ingroup base64 */ char *base64_encode(const char *in, size_t size) { char *out; size_t outlen; if(in == NULL) return(NULL); if(size == 0) size = strlen(in); outlen = base64_encoded_size(size); if((out = (char *)malloc(sizeof(char) * (outlen + 1))) == NULL) return(NULL); base64_encode_binary(out, (unsigned char *)in, size); return(out); } /** Decode a string. This is a convenience function. It decodes the * null-terminated string pointed to by \c in, stores the result in a newly * created memory area and returns a pointer to it. The result will be * null-terminated. * * @attention After a call to base64_decode(), you have to free() the result * yourself. * * @param in pointer to string * @returns NULL on error (not enough memory) or a pointer to the decoded result * * @ingroup base64 */ char *base64_decode(const char *in) { char *out; size_t outlen; int numbytes; outlen = base64_decoded_size(strlen(in)); if((out = (char *)malloc(sizeof(char) * (outlen + 1))) == NULL) return(NULL); if((numbytes = base64_decode_binary((unsigned char *)out, in)) < 0) { free(out); return(NULL); } *(out + numbytes) = '\0'; return(out); }