From 3914ec6505021df1b3edac7a0b2648ace33e4ef4 Mon Sep 17 00:00:00 2001 From: scuri Date: Wed, 2 Dec 2009 19:58:44 +0000 Subject: *** empty log message *** --- src/svg/base64.c | 231 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 231 insertions(+) create mode 100644 src/svg/base64.c (limited to 'src/svg/base64.c') diff --git a/src/svg/base64.c b/src/svg/base64.c new file mode 100644 index 0000000..c01b130 --- /dev/null +++ b/src/svg/base64.c @@ -0,0 +1,231 @@ +/*********************************************************************** +=============== +BASE64 Encoding +=============== +Available on: http://freecode-freecode.blogspot.com/2008/02/base64c.html +Last access in: November, 10th 2009. +************************************************************************/ + +#include "stdio.h" +#include "stdlib.h" +#include "string.h" +#include "base64.h" + +/** + * characters used for Base64 encoding + */ +const char *BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +/** + * encode three bytes using base64 (RFC 3548) + * + * @param triple three bytes that should be encoded + * @param result buffer of four characters where the result is stored + */ +void _base64_encode_triple(unsigned char triple[3], char result[4]) +{ + int tripleValue, i; + + tripleValue = triple[0]; + tripleValue *= 256; + tripleValue += triple[1]; + tripleValue *= 256; + tripleValue += triple[2]; + + for (i=0; i<4; i++) + { + result[3-i] = BASE64_CHARS[tripleValue%64]; + tripleValue /= 64; + } +} + +/** + * encode an array of bytes using Base64 (RFC 3548) + * + * @param source the source buffer + * @param sourcelen the length of the source buffer + * @param target the target buffer + * @param targetlen the length of the target buffer + * @return 1 on success, 0 otherwise + */ +int base64_encode(unsigned char *source, int sourcelen, char *target, int targetlen) +{ + /* check if the result will fit in the target buffer */ + if ((sourcelen+2)/3*4 > targetlen-1) + return 0; + + /* encode all full triples */ + while (sourcelen >= 3) + { + _base64_encode_triple(source, target); + sourcelen -= 3; + source += 3; + target += 4; + } + + /* encode the last one or two characters */ + if (sourcelen > 0) + { + unsigned char temp[3]; + memset(temp, 0, sizeof(temp)); + memcpy(temp, source, sourcelen); + _base64_encode_triple(temp, target); + target[3] = '='; + + if (sourcelen == 1) + target[2] = '='; + + target += 4; + } + + /* terminate the string */ + target[0] = 0; + + return 1; +} + +/** + * determine the value of a base64 encoding character + * + * @param base64char the character of which the value is searched + * @return the value in case of success (0-63), -1 on failure + */ +int _base64_char_value(char base64char) +{ + if (base64char >= 'A' && base64char <= 'Z') + return base64char-'A'; + + if (base64char >= 'a' && base64char <= 'z') + return base64char-'a'+26; + + if (base64char >= '0' && base64char <= '9') + return base64char-'0'+2*26; + + if (base64char == '+') + return 2*26+10; + + if (base64char == '/') + return 2*26+11; + + return -1; +} + +/** + * decode a 4 char base64 encoded byte triple + * + * @param quadruple the 4 characters that should be decoded + * @param result the decoded data + * @return lenth of the result (1, 2 or 3), 0 on failure + */ +int _base64_decode_triple(char quadruple[4], unsigned char *result) +{ + int i, triple_value, bytes_to_decode = 3, only_equals_yet = 1; + int char_value[4]; + + for (i=0; i<4; i++) + char_value[i] = _base64_char_value(quadruple[i]); + + /* check if the characters are valid */ + for (i=3; i>=0; i--) + { + if (char_value[i]<0) + { + if (only_equals_yet && quadruple[i]=='=') + { + /* we will ignore this character anyway, make it something + * that does not break our calculations */ + + char_value[i]=0; + bytes_to_decode--; + continue; + } + return 0; + } + + /* after we got a real character, no other '=' are allowed anymore */ + only_equals_yet = 0; + } + + /* if we got "====" as input, bytes_to_decode is -1 */ + if (bytes_to_decode < 0) + bytes_to_decode = 0; + + /* make one big value out of the partial values */ + triple_value = char_value[0]; + triple_value *= 64; + triple_value += char_value[1]; + triple_value *= 64; + triple_value += char_value[2]; + triple_value *= 64; + triple_value += char_value[3]; + + /* break the big value into bytes */ + for (i=bytes_to_decode; i<3; i++) + triple_value /= 256; + + for (i=bytes_to_decode-1; i>=0; i--) + { + result[i] = triple_value%256; + triple_value /= 256; + } + + return bytes_to_decode; +} + +/** + * decode base64 encoded data + * + * @param source the encoded data (zero terminated) + * @param target pointer to the target buffer + * @param targetlen length of the target buffer + * @return length of converted data on success, -1 otherwise + */ +int base64_decode(char *source, unsigned char *target, int targetlen) +{ + char *src, *tmpptr; + char quadruple[4], tmpresult[3]; + int i, tmplen = 3; + int converted = 0; + + /* concatenate '===' to the source to handle unpadded base64 data */ + src = (char *)malloc(strlen(source)+5); + if (src == NULL) + return -1; + + strcpy(src, source); + strcat(src, "===="); + tmpptr = src; + + /* convert as long as we get a full result */ + while (tmplen == 3) + { + /* get 4 characters to convert */ + for (i=0; i<4; i++) + { + /* skip invalid characters - we won't reach the end */ + while (*tmpptr != '=' && _base64_char_value(*tmpptr)<0) + tmpptr++; + + quadruple[i] = *(tmpptr++); + } + + /* convert the characters */ + tmplen = _base64_decode_triple(quadruple, (unsigned char*)tmpresult); + + /* check if the fit in the result buffer */ + if (targetlen < tmplen) + { + free(src); + return -1; + } + + /* put the partial result in the result buffer */ + memcpy(target, tmpresult, tmplen); + target += tmplen; + targetlen -= tmplen; + converted += tmplen; + } + + free(src); + return converted; +} -- cgit v1.2.3