first implementation of base64_decode()

src/base64.c

@@ -26,10 +26,11 @@
  *
  */
 
-#include <stdio.h>
+#include <errno.h>
 
 #include "vmod_convert.h"
 
+#include "vrt.h"
 #include "vas.h"
 
 struct b64_state_s {
@@ -59,6 +60,21 @@ alpha_init(struct b64_alphabet *alpha)
 		alpha->i64[alpha->padding] = 0;
 }
 
+static inline int
+decode3(char *restrict *restrict dest, char *restrict const buf,
+	const size_t maxlen, unsigned u)
+{
+	char *d = *dest;
+	for (int i = 0; i < 3; i++) {
+		if (d == buf + maxlen)
+			return -1;
+		*d++ = (u >> 16) & 0xff;
+		u <<= 8;
+	}
+	*dest += d - *dest;
+	return 1;
+}
+
 void
 base64_init(void)
 {
@@ -160,3 +176,46 @@ base64_encode(const enum encoding enc, char *restrict const buf,
 	assert(outlen > 0);
 	return p - buf;
 }
+
+ssize_t
+base64_decode(const enum encoding dec, char *restrict const buf,
+	      const size_t maxlen, const char *restrict const p, va_list ap)
+{
+	struct b64_alphabet *alpha = &b64_alphabet[dec];
+	const char *s;
+	char *dest = buf;
+	unsigned u = 0;
+	int n;
+
+	AN(buf);
+
+	for (s = p; s != vrt_magic_string_end; s = va_arg(ap, const char *)) {
+		if (s == NULL)
+			continue;
+		while (*s) {
+			for (n = 0; n < 4; n++) {
+				char b = alpha->i64[(unsigned) *s++];
+				if (b < 0) {
+					errno = EINVAL;
+					return -1;
+				}
+				u <<= 6;
+				u |= (unsigned) b;
+				if (!*s)
+					break;
+			}
+			if (n == 4)
+				if (decode3(&dest, buf, maxlen, u) < 0) {
+					errno = ENOMEM;
+					return -1;
+				}
+		}
+	}
+	if (n != 4)
+		if (decode3(&dest, buf, maxlen, u) < 0) {
+			errno = ENOMEM;
+			return -1;
+		}
+
+	return dest - buf;
+}

src/tests/base64.vtc

@@ -35,6 +35,15 @@ varnish v1 -vcl+backend {
 	    set resp.http.b64urlnopadxcode =
 	      convert.transcode(IDENTITY, BASE64URLNOPAD,
 				req.url + "Hello world" + req.url);
+
+	    set resp.http.dec = convert.encode(IDENTITY,
+				convert.decode(BASE64, "L0hlbGxvIHdvcmxkLw=="));
+
+	    set resp.http.dec2
+	      = convert.encode(IDENTITY,
+		convert.decode(BASE64,
+	        "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wcyBvdmVyIHRoZSBsYXp5IGRvZw=="
+			      ));
 	}
 } -start
 
@@ -47,6 +56,8 @@ client c1 {
 	expect resp.http.b64xcode == "L0hlbGxvIHdvcmxkLw=="
 	expect resp.http.b64urlxcode == "L0hlbGxvIHdvcmxkLw=="
 	expect resp.http.b64urlnopadxcode == "L0hlbGxvIHdvcmxkLw"
+	expect resp.http.dec == "/Hello world/"
+	expect resp.http.dec2 == "The quick brown fox jumps over the lazy dog"
 }
 
 client c1 -run

src/vmod_convert.c

@@ -116,6 +116,10 @@ decode(const enum encoding dec, char *restrict const buf,
 	switch(dec) {
 	case IDENTITY:
 		return id_decode(dec, buf, maxlen, p, ap);
+	case BASE64:
+	case BASE64URL:
+	case BASE64URLNOPAD:
+		return base64_decode(dec, buf, maxlen, p, ap);
 	case HEX:
 		return hex_decode(dec, buf, maxlen, p, ap);
 	default:
@@ -206,7 +210,8 @@ vmod_encode(VRT_CTX, VCL_ENUM encs, VCL_BLOB b) {
 	ssize_t len;
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
-	AN(b);
+	if (b == NULL)
+		return NULL;
 
 	if (wb_create(ctx->ws, &wb) == NULL)
 		return NULL;

src/vmod_convert.h

@@ -107,6 +107,7 @@ decode_f id_decode;
 /* base64.c */
 void base64_init(void);
 encode_f base64_encode;
+decode_f base64_decode;
 
 /* hex.c */
 encode_f hex_encode;