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#include "textcode.h"
#include "haveinline.h"
static inline int dec(unsigned char x) {
if (x>='A' && x<='Z') return x-'A';
if (x>='a' && x<='z') return x-'a'+26;
if (x>='0' && x<='9') return x-'0'+26+26;
switch (x) {
case '-': return 62;
case '_': return 63;
default: return -1;
}
}
size_t scan_base64url(const char *src,char *dest,size_t *destlen) {
unsigned short tmp=0,bits=0;
register const unsigned char* s=(const unsigned char*) src;
size_t i;
for (i=0;;) {
int a=dec(*s);
if (a<0) break; /* base64url does not have padding */
tmp=(tmp<<6)|a; bits+=6;
++s;
if (bits>=8) {
bits-=8;
if (dest) dest[i]=(tmp>>bits);
++i;
}
}
if (destlen) *destlen=i;
return (const char*)s-src;
}
#ifdef UNITTEST
#include <assert.h>
#include <string.h>
#include <stdio.h>
int main() {
char buf[100];
size_t l;
/* check that we don't consume padding */
memset(buf,0,10); assert(scan_base64url("Zm5vcmQ=",buf,&l)==7 && l==5 && !memcmp(buf,"fnord",6));
/* check that we don't insist on the padding */
memset(buf,0,10); assert(scan_base64url("Zm5vcmQ",buf,&l)==7 && l==5 && !memcmp(buf,"fnord",6));
/* check the special non-isalnum chars :) */
memset(buf,0,10); assert(scan_base64url("_-8=",buf,&l)==3 && l==2 && !memcmp(buf,"\xff\xef",3));
return 0;
}
#endif
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