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#include "first.h"
#include "base64.h"
/* reverse mapping:
* >= 0: base64 value
* -1: invalid character
* -2: skip character (whitespace/control)
* -3: padding
*/
/* BASE64_STANDARD: "A-Z a-z 0-9 + /" maps to 0-63, pad with "=" */
static const char base64_standard_table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
static const signed char base64_standard_reverse_table[] = {
/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
-1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x00 - 0x0F */
-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x10 - 0x1F */
-2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 0x20 - 0x2F */
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1, /* 0x30 - 0x3F */
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 0x40 - 0x4F */
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 0x50 - 0x5F */
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 0x60 - 0x6F */
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 0x70 - 0x7F */
};
/* BASE64_URL: "A-Z a-z 0-9 - _" maps to 0-63, pad with "=" */
static const char base64_url_table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=";
static const signed char base64_url_reverse_table[] = {
/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
-1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x00 - 0x0F */
-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x10 - 0x1F */
-2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, /* 0x20 - 0x2F */
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1, /* 0x30 - 0x3F */
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 0x40 - 0x4F */
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, /* 0x50 - 0x5F */
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 0x60 - 0x6F */
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 0x70 - 0x7F */
};
size_t li_base64_dec(unsigned char * const result, const size_t out_length, const char * const in, const size_t in_length, const base64_charset charset) {
size_t i;
const signed char * const base64_reverse_table = (charset)
? base64_url_reverse_table /* BASE64_URL */
: base64_standard_reverse_table; /* BASE64_STANDARD */
int_fast32_t ch = 0;
int_fast32_t out4 = 0;
size_t out_pos = 0;
for (i = 0; i < in_length; i++) {
const uint_fast32_t c = ((unsigned char *)in)[i];
ch = (c < 128) ? base64_reverse_table[c] : -1;
if (__builtin_expect( (ch < 0), 0)) {
/* skip formatted base64; skip whitespace ('\r' '\n' '\t' ' ')*/
if (-2 == ch) /*(loose check; skip ' ', all ctrls not \127 or \0)*/
continue; /* skip character */
break;
}
out4 = (out4 << 6) | ch;
if ((i & 3) == 3) {
result[out_pos] = (out4 >> 16) & 0xFF;
result[out_pos+1] = (out4 >> 8) & 0xFF;
result[out_pos+2] = (out4 ) & 0xFF;
out_pos += 3;
out4 = 0;
}
}
/* permit base64 string ending with pad chars (ch == -3); not checking
* for one or two pad chars + optional whitespace reaches in_length) */
/* permit base64 string truncated before in_length (in[i] == '\0') */
switch (i == in_length || ch == -3 || in[i] != '\0' ? (i & 3) : 1) {
case 3:
result[out_pos++] = (out4 >> 10);
out4 <<= 2;
__attribute_fallthrough__
case 2:
result[out_pos++] = (out4 >> 4) & 0xFF;
__attribute_fallthrough__
case 0:
force_assert(out_pos <= out_length);
return out_pos;
case 1: /* pad char or str end can only come after 2+ base64 chars */
default:
return 0; /* invalid character, abort */
}
}
size_t li_base64_enc(char * const restrict out, const size_t out_length, const unsigned char * const restrict in, const size_t in_length, const base64_charset charset, const int pad) {
size_t i;
size_t out_pos = 0;
uint_fast32_t v;
const char* const base64_table = (charset)
? base64_url_table /* BASE64_URL */
: base64_standard_table; /* BASE64_STANDARD */
const char padchar = base64_table[64]; /* padding char */
/* check overflows */
/* 1073741823 is max num full_tuples to avoid overflow in uint32_t;
* and (1 GB - 1) is ridiculously large for base64-encoded data */
force_assert(in_length <= 3221225469); /* (3221225469+2) / 3 * 4 < UINT32_MAX */
force_assert((in_length+2)/3*4 <= out_length);
for (i = 2; i < in_length; i += 3) {
v = (in[i-2] << 16) | (in[i-1] << 8) | in[i];
out[out_pos+0] = base64_table[(v >> 18) & 0x3f];
out[out_pos+1] = base64_table[(v >> 12) & 0x3f];
out[out_pos+2] = base64_table[(v >> 6) & 0x3f];
out[out_pos+3] = base64_table[(v ) & 0x3f];
out_pos += 4;
}
switch (in_length - (i-2)) {
case 0:
default:
break;
case 1:
{
/* pretend in[i-1] = in[i] = 0, don't write last two (out_pos+3, out_pos+2) characters */
v = (in[i-2] << 4);
out[out_pos+0] = base64_table[(v >> 6) & 0x3f];
out[out_pos+1] = base64_table[(v ) & 0x3f];
if (pad) {
out[out_pos+2] = out[out_pos+3] = padchar;
out_pos += 4;
}
else
out_pos += 2;
}
break;
case 2:
{
/* pretend in[i] = 0, don't write last (out_pos+3) character */
v = (in[i-2] << 10) | (in[i-1] << 2);
out[out_pos+0] = base64_table[(v >> 12) & 0x3f];
out[out_pos+1] = base64_table[(v >> 6) & 0x3f];
out[out_pos+2] = base64_table[(v ) & 0x3f];
if (pad) {
out[out_pos+3] = padchar;
out_pos += 4;
}
else
out_pos += 3;
}
break;
}
return out_pos;
}
char* buffer_append_base64_enc(buffer *out, const unsigned char* in, size_t in_length, base64_charset charset, int pad) {
const size_t reserve = (in_length+2)/3*4;
char * const result = buffer_string_prepare_append(out, reserve);
const size_t out_pos =
li_base64_enc(result, reserve, in, in_length, charset, pad);
buffer_commit(out, out_pos);
return result;
}
unsigned char* buffer_append_base64_decode(buffer *out, const char* in, size_t in_length, base64_charset charset) {
const size_t reserve = 3*(in_length/4) + 3;
unsigned char * const result = (unsigned char *)
buffer_string_prepare_append(out, reserve);
const size_t out_pos =
li_base64_dec(result, reserve, in, in_length, charset);
buffer_commit(out, out_pos);
return (out_pos || !in_length) ? result : NULL;
}