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authorDavid Robillard <d@drobilla.net>2018-05-12 12:47:18 +0200
committerDavid Robillard <d@drobilla.net>2018-12-30 17:58:17 -0500
commitc6daba398ccff8674978fc4efcdfc3e95272726c (patch)
treee7f75a310e8b57a9bcf88c7ffd15556c86f7a913 /src/base64.c
parent9e84cf75e8c4dcfb1ac90f50471b0d64aae541e4 (diff)
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Separate base64 implementation
Diffstat (limited to 'src/base64.c')
-rw-r--r--src/base64.c124
1 files changed, 124 insertions, 0 deletions
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 <http://drobilla.net>
+
+ 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 <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+/**
+ Base64 encoding table.
+
+ @see <a href="http://tools.ietf.org/html/rfc3548#section-3">RFC3986 S3</a>.
+*/
+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;
+}