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base64.c
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base64.c
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#include <uv.h>
#include <lua.h>
#include <stdlib.h>
#include <string.h>
#include "utils.h"
static const char b64_alphabet[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
static inline void a3_to_a4(unsigned char *a4, unsigned char *a3) {
a4[0] = (a3[0] & 0xfc) >> 2;
a4[1] = ((a3[0] & 0x03) << 4) + ((a3[1] & 0xf0) >> 4);
a4[2] = ((a3[1] & 0x0f) << 2) + ((a3[2] & 0xc0) >> 6);
a4[3] = (a3[2] & 0x3f);
}
static inline void a4_to_a3(unsigned char *a3, unsigned char *a4) {
a3[0] = (a4[0] << 2) + ((a4[1] & 0x30) >> 4);
a3[1] = ((a4[1] & 0xf) << 4) + ((a4[2] & 0x3c) >> 2);
a3[2] = ((a4[2] & 0x3) << 6) + a4[3];
}
static inline unsigned char b64_lookup(char c) {
if (c >='A' && c <='Z') return c - 'A';
if (c >='a' && c <='z') return c - 71;
if (c >='0' && c <='9') return c + 4;
if (c == '+') return 62;
if (c == '/') return 63;
return -1;
}
static int base64_encode(char *output, char *input, int inputLen) {
int i = 0, j = 0;
int encLen = 0;
unsigned char a3[3];
unsigned char a4[4];
while (inputLen--) {
a3[i++] = *(input++);
if (i == 3) {
a3_to_a4(a4, a3);
for (i = 0; i < 4; i++) {
output[encLen++] = b64_alphabet[a4[i]];
}
i = 0;
}
}
if (i) {
for (j = i; j < 3; j++) {
a3[j] = '\0';
}
a3_to_a4(a4, a3);
for (j = 0; j < i + 1; j++) {
output[encLen++] = b64_alphabet[a4[j]];
}
while ((i++ < 3)) {
output[encLen++] = '=';
}
}
output[encLen] = '\0';
return encLen;
}
static int base64_decode(char *output, char *input, int inputLen) {
int i = 0, j = 0;
int decLen = 0;
unsigned char a3[3];
unsigned char a4[4];
while (inputLen--) {
if (*input == '=') {
break;
}
a4[i++] = *(input++);
if (i == 4) {
for (i = 0; i <4; i++) {
a4[i] = b64_lookup(a4[i]);
}
a4_to_a3(a3,a4);
for (i = 0; i < 3; i++) {
output[decLen++] = a3[i];
}
i = 0;
}
}
if (i) {
for (j = i; j < 4; j++) {
a4[j] = '\0';
}
for (j = 0; j <4; j++) {
a4[j] = b64_lookup(a4[j]);
}
a4_to_a3(a3,a4);
for (j = 0; j < i - 1; j++) {
output[decLen++] = a3[j];
}
}
output[decLen] = '\0';
return decLen;
}
static int base64_enc_len(int plainLen) {
int n = plainLen;
return (n + 2 - ((n + 2) % 3)) / 3 * 4;
}
static int base64_dec_len(char *input, int inputLen) {
int i = 0;
int numEq = 0;
for (i = inputLen - 1; input[i] == '='; i--) {
numEq++;
}
return ((6 * inputLen) / 8) - numEq;
}
static int lua_base64_encode(lua_State *L) {
char *in = (char *)lua_tostring(L, 1);
if (in == NULL)
panic("in is nil");
int inlen = strlen(in);
int outlen = base64_enc_len(inlen);
char *out = (char *)zalloc(outlen+1);
base64_encode(out, in, inlen);
lua_pushstring(L, out);
free(out);
return 1;
}
static int lua_base64_decode(lua_State *L) {
char *in = (char *)lua_tostring(L, 1);
if (in == NULL)
panic("in is nil");
int inlen = strlen(in);
int outlen = base64_dec_len(in, inlen);
char *out = (char *)zalloc(outlen+1);
base64_decode(out, in, inlen);
lua_pushstring(L, out);
free(out);
return 1;
}
void luv_base64_init(lua_State *L, uv_loop_t *loop) {
lua_pushcfunction(L, lua_base64_encode);
lua_setglobal(L, "base64_encode");
lua_pushcfunction(L, lua_base64_decode);
lua_setglobal(L, "base64_decode");
}