Add a helper function for encoding into mime base64

src/libckpool.c

@@ -370,6 +370,59 @@ void b58tobin(uchar *b58bin, const uchar *b58)
 	}
 }
 
+static const char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+/* Return a malloced string of *src encoded into mime base 64 */
+uchar *http_base64(const uchar *src)
+{
+	uchar *str, *dst;
+	size_t l, hlen;
+	int t, r;
+
+	l = strlen((const char *)src);
+	hlen = ((l + 2) / 3) * 4 + 1;
+	align_len(&hlen);
+	str = malloc(hlen);
+	if (unlikely(!str))
+		return str;
+	dst = str;
+	r = 0;
+
+	while (l >= 3) {
+		t = (src[0] << 16) | (src[1] << 8) | src[2];
+		dst[0] = base64[(t >> 18) & 0x3f];
+		dst[1] = base64[(t >> 12) & 0x3f];
+		dst[2] = base64[(t >> 6) & 0x3f];
+		dst[3] = base64[(t >> 0) & 0x3f];
+		src += 3; l -= 3;
+		dst += 4; r += 4;
+	}
+
+	switch (l) {
+		case 2:
+			t = (src[0] << 16) | (src[1] << 8);
+			dst[0] = base64[(t >> 18) & 0x3f];
+			dst[1] = base64[(t >> 12) & 0x3f];
+			dst[2] = base64[(t >> 6) & 0x3f];
+			dst[3] = '=';
+			dst += 4;
+			r += 4;
+			break;
+		case 1:
+			t = src[0] << 16;
+			dst[0] = base64[(t >> 18) & 0x3f];
+			dst[1] = base64[(t >> 12) & 0x3f];
+			dst[2] = dst[3] = '=';
+			dst += 4;
+			r += 4;
+			break;
+		case 0:
+			break;
+	}
+	*dst = 0;
+	return (str);
+}
+
 void address_to_pubkeytxn(uchar *pkh, const uchar *addr)
 {
 	uchar b58bin[25];

src/libckpool.h

@@ -116,6 +116,7 @@ void align_len(size_t *len);
 void __bin2hex(uchar *s, const uchar *p, size_t len);
 void *bin2hex(const uchar *p, size_t len);
 bool hex2bin(uchar *p, const uchar *hexstr, size_t len);
+uchar *http_base64(const uchar *src);
 void b58tobin(uchar *b58bin, const uchar *b58);
 void address_to_pubkeytxn(uchar *pkh, const uchar *addr);
 int ser_number(uchar *s, int32_t val);