From c6daba398ccff8674978fc4efcdfc3e95272726c Mon Sep 17 00:00:00 2001 From: David Robillard Date: Sat, 12 May 2018 12:47:18 +0200 Subject: Separate base64 implementation --- src/base64.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 src/base64.c (limited to 'src/base64.c') diff --git a/src/base64.c b/src/base64.c new file mode 100644 index 00000000..7bc4a127 --- /dev/null +++ b/src/base64.c @@ -0,0 +1,124 @@ +/* + Copyright 2011-2018 David Robillard + + Permission to use, copy, modify, and/or distribute this software for any + purpose with or without fee is hereby granted, provided that the above + copyright notice and this permission notice appear in all copies. + + THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +*/ + +#include "base64.h" + +#include "serd_internal.h" +#include "string_utils.h" + +#include +#include +#include + +/** + Base64 encoding table. + + @see RFC3986 S3. +*/ +static const uint8_t b64_map[] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +/** + Base64 decoding table. + + This is indexed by encoded characters and returns the numeric value used + for decoding, shifted up by 47 to be in the range of printable ASCII. + A '$' is a placeholder for characters not in the base64 alphabet. +*/ +static const char b64_unmap[] = + "$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$m$$$ncdefghijkl$$$$$$" + "$/0123456789:;<=>?@ABCDEFGH$$$$$$IJKLMNOPQRSTUVWXYZ[\\]^_`ab$$$$" + "$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$" + "$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$"; + +/** Encode 3 raw bytes to 4 base64 characters. */ +static inline void +encode_chunk(uint8_t out[4], const uint8_t in[3], size_t n_in) +{ + out[0] = b64_map[in[0] >> 2]; + out[1] = b64_map[((in[0] & 0x03) << 4) | ((in[1] & 0xF0) >> 4)]; + out[2] = ((n_in > 1) + ? (b64_map[((in[1] & 0x0F) << 2) | ((in[2] & 0xC0) >> 6)]) + : (uint8_t)'='); + out[3] = ((n_in > 2) ? b64_map[in[2] & 0x3F] : (uint8_t)'='); +} + +size_t +serd_base64_get_length(const size_t size, const bool wrap_lines) +{ + return (size + 2) / 3 * 4 + (wrap_lines * ((size - 1) / 57)); +} + +bool +serd_base64_encode(char* const str, + const void* const buf, + const size_t size, + const bool wrap_lines) +{ + uint8_t* const out = (uint8_t*)str; + bool has_newline = false; + for (size_t i = 0, j = 0; i < size; i += 3, j += 4) { + uint8_t in[4] = { 0, 0, 0, 0 }; + size_t n_in = MIN(3, size - i); + memcpy(in, (const uint8_t*)buf + i, n_in); + + if (wrap_lines && i > 0 && (i % 57) == 0) { + out[j++] = '\n'; + has_newline = true; + } + + encode_chunk(out + j, in, n_in); + } + + return has_newline; +} + +static inline uint8_t +unmap(const uint8_t in) +{ + return b64_unmap[in] - 47; +} + +/** Decode 4 base64 characters to 3 raw bytes. */ +static inline size_t +decode_chunk(const uint8_t in[4], uint8_t out[3]) +{ + out[0] = (uint8_t)(((unmap(in[0]) << 2)) | unmap(in[1]) >> 4); + out[1] = (uint8_t)(((unmap(in[1]) << 4) & 0xF0) | unmap(in[2]) >> 2); + out[2] = (uint8_t)(((unmap(in[2]) << 6) & 0xC0) | unmap(in[3])); + return 1 + (in[2] != '=') + ((in[2] != '=') && (in[3] != '=')); +} + +void* +serd_base64_decode(const char* str, size_t len, size_t* size) +{ + const uint8_t* ustr = (const uint8_t*)str; + + void* buf = malloc((len * 3) / 4 + 2); + *size = 0; + for (size_t i = 0, j = 0; i < len; j += 3) { + uint8_t in[] = "===="; + size_t n_in = 0; + for (; i < len && n_in < 4; ++n_in) { + for (; i < len && !is_base64(ustr[i]); ++i) {} // Skip junk + in[n_in] = ustr[i++]; + } + if (n_in > 1) { + *size += decode_chunk(in, (uint8_t*)buf + j); + } + } + return buf; +} -- cgit v1.2.1