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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, -3, -1, /* 0x20 - 0x2F */
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -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 */
};
unsigned char* buffer_append_base64_decode(buffer *out, const char* in, size_t in_length, base64_charset charset) {
unsigned char *result;
size_t out_pos = 0; /* current output character (position) that is decoded. can contain partial result */
unsigned int group = 0; /* how many base64 digits in the current group were decoded already. each group has up to 4 digits */
size_t i;
const signed char *base64_reverse_table;
switch (charset) {
case BASE64_STANDARD:
base64_reverse_table = base64_standard_reverse_table;
break;
case BASE64_URL:
base64_reverse_table = base64_url_reverse_table;
break;
default:
return NULL;
}
result = (unsigned char *) buffer_string_prepare_append(out, 3*(in_length / 4) + 3);
/* run through the whole string, converting as we go */
for (i = 0; i < in_length; i++) {
unsigned char c = (unsigned char) in[i];
int ch;
if (c == '\0') break;
if (c >= 128) return NULL; /* only 7-bit characters allowed */
ch = base64_reverse_table[c];
if (-3 == ch) {
/* pad character; can only come after 2 base64 digits in a group */
if (group < 2) return NULL;
break;
} else if (-2 == ch) {
continue; /* skip character */
} else if (ch < 0) {
return NULL; /* invalid character, abort */
}
switch(group) {
case 0:
result[out_pos] = ch << 2;
group = 1;
break;
case 1:
result[out_pos++] |= ch >> 4;
result[out_pos] = (ch & 0x0f) << 4;
group = 2;
break;
case 2:
result[out_pos++] |= ch >>2;
result[out_pos] = (ch & 0x03) << 6;
group = 3;
break;
case 3:
result[out_pos++] |= ch;
group = 0;
break;
}
}
switch(group) {
case 0:
/* ended on boundary */
break;
case 1:
/* need at least 2 base64 digits per group */
return NULL;
case 2:
/* have 2 base64 digits in last group => one real octect, two zeroes padded */
case 3:
/* have 3 base64 digits in last group => two real octects, one zero padded */
/* for both cases the current index already is on the first zero padded octet
* - check it really is zero (overlapping bits) */
if (0 != result[out_pos]) return NULL;
break;
}
buffer_commit(out, out_pos);
return result;
}
size_t li_to_base64_no_padding(char* out, size_t out_length, const unsigned char* in, size_t in_length, base64_charset charset) {
const size_t full_tuples = in_length / 3;
const size_t in_tuple_remainder = in_length % 3;
const size_t out_tuple_remainder = in_tuple_remainder ? 1 + in_tuple_remainder : 0;
const size_t require_space = 4 * full_tuples + out_tuple_remainder;
const char* base64_table;
size_t i;
size_t out_pos = 0;
switch (charset) {
case BASE64_STANDARD:
base64_table = base64_standard_table;
break;
case BASE64_URL:
base64_table = base64_url_table;
break;
default:
force_assert(0 && "invalid charset");
}
/* check overflows */
force_assert(full_tuples <= 2*full_tuples);
force_assert(full_tuples <= 4*full_tuples);
force_assert(4*full_tuples <= 4*full_tuples + out_tuple_remainder);
force_assert(require_space <= out_length);
for (i = 2; i < in_length; i += 3) {
unsigned int v = (in[i-2] << 16) | (in[i-1] << 8) | in[i];
out[out_pos+3] = base64_table[v & 0x3f]; v >>= 6;
out[out_pos+2] = base64_table[v & 0x3f]; v >>= 6;
out[out_pos+1] = base64_table[v & 0x3f]; v >>= 6;
out[out_pos+0] = base64_table[v & 0x3f];
out_pos += 4;
}
switch (in_tuple_remainder) {
case 0:
break;
case 1:
{
/* pretend in[i-1] = in[i] = 0, don't write last two (out_pos+3, out_pos+2) characters */
unsigned int v = (in[i-2] << 4);
out[out_pos+1] = base64_table[v & 0x3f]; v >>= 6;
out[out_pos+0] = base64_table[v & 0x3f];
out_pos += 2;
}
break;
case 2:
{
/* pretend in[i] = 0, don't write last (out_pos+3) character */
unsigned int v = (in[i-2] << 10) | (in[i-1] << 2);
out[out_pos+2] = base64_table[v & 0x3f]; v >>= 6;
out[out_pos+1] = base64_table[v & 0x3f]; v >>= 6;
out[out_pos+0] = base64_table[v & 0x3f];
out_pos += 3;
}
break;
}
force_assert(out_pos <= out_length);
return out_pos;
}
size_t li_to_base64(char* out, size_t out_length, const unsigned char* in, size_t in_length, base64_charset charset) {
const size_t in_tuple_remainder = in_length % 3;
size_t padding_length = in_tuple_remainder ? 3 - in_tuple_remainder : 0;
char padding;
size_t out_pos;
switch (charset) {
case BASE64_STANDARD:
padding = base64_standard_table[64];
break;
case BASE64_URL:
padding = base64_url_table[64];
break;
default:
force_assert(0 && "invalid charset");
}
force_assert(out_length >= padding_length);
out_pos = li_to_base64_no_padding(out, out_length - padding_length, in, in_length, charset);
while (padding_length > 0) {
out[out_pos++] = padding;
padding_length--;
}
force_assert(out_pos <= out_length);
return out_pos;
}
char* buffer_append_base64_encode_no_padding(buffer *out, const unsigned char* in, size_t in_length, base64_charset charset) {
size_t reserve = 4*(in_length/3) + 4;
char* result = buffer_string_prepare_append(out, reserve);
size_t out_pos = li_to_base64_no_padding(result, reserve, in, in_length, charset);
buffer_commit(out, out_pos);
return result;
}
char* buffer_append_base64_encode(buffer *out, const unsigned char* in, size_t in_length, base64_charset charset) {
size_t reserve = 4*(in_length/3) + 4;
char* result = buffer_string_prepare_append(out, reserve);
size_t out_pos = li_to_base64(result, reserve, in, in_length, charset);
buffer_commit(out, out_pos);
return result;
}
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