add base64url support

test/textcode.c

@@ -1,7 +1,10 @@
 #include "array.h"
 #include "textcode.h"
+#include <string.h>
+#include <stdio.h>
 #include <assert.h>
 #include <unistd.h>
+#include <write12.h>
 
 array a;
 
@@ -26,5 +29,11 @@ int main() {
   buf[n]=0;
   puts(buf);
 
+  assert(fmt_base64(buf,"fnörd",6)==8 && !memcmp(buf,"Zm7DtnJk",8));
+  assert(scan_base64("Zm7DtnJk",buf,&n)==8 && n==6 && !memcmp(buf,"fnörd",6));
+  assert(fmt_base64(buf,"x",1)==4 && !memcmp(buf,"eA==",4));
+  assert(scan_base64("eA====",buf,&n)==4 && n==1 && buf[0]=='x');
+  assert(fmt_base64url(buf,"\xef\xbf\xbdx",4)==6 && !memcmp(buf,"77-9eA",6));
+  assert(scan_base64url("77-9eA",buf,&n)==6 && n==4 && !memcmp(buf,"\xef\xbf\xbdx",4));
   return 0;
 }

textcode/base64url.c

@@ -0,0 +1 @@
+const char base64url[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=";

textcode/fmt_base64url.c

@@ -0,0 +1,24 @@
+#include "fmt.h"
+#include "textcode.h"
+#include "haveinline.h"
+
+size_t fmt_base64url(char* dest,const char* src,size_t len) {
+  register const unsigned char* s=(const unsigned char*) src;
+  unsigned short bits=0,temp=0;
+  size_t written=0,i;
+  if (!dest) return (len>((size_t)-1)/2)?(size_t)-1:((len+2)/3)*4;
+  for (i=0; i<len; ++i) {
+    temp<<=8; temp+=s[i]; bits+=8;
+    while (bits>6) {
+      dest[written]=base64url[((temp>>(bits-6))&63)];
+      ++written; bits-=6;
+    }
+  }
+  if (bits) {
+    temp<<=(6-bits);
+    dest[written]=base64url[temp&63];
+    ++written;
+  }
+  /* no padding for base64url */
+  return written;
+}

textcode/scan_base64.c

@@ -19,7 +19,7 @@ size_t scan_base64(const char *src,char *dest,size_t *destlen) {
   for (;;) {
     int a=dec(*s);
     if (a<0) {
-      while (*s=='=') ++s;
+      while (*s=='=' && ((s-(const unsigned char*)src)&3)) ++s;
       break;
     }
     tmp=(tmp<<6)|a; bits+=6;

textcode/scan_base64url.c

@@ -0,0 +1,31 @@
+#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;
+  const char* orig=dest;
+  for (;;) {
+    int a=dec(*s);
+    if (a<0) break;
+    tmp=(tmp<<6)|a; bits+=6;
+    ++s;
+    if (bits>=8) {
+      *dest=(tmp>>(bits-=8));
+      ++dest;
+    }
+  }
+  *destlen=dest-orig;
+  return (const char*)s-src;
+}