add decode_n() and transcode_n()

Patch by Nils Goroll <nils.goroll@uplex.de>

src/base64.c

@@ -121,7 +121,8 @@ base64_encode(const enum encoding enc, char *restrict const buf,
 
 ssize_t
 base64_decode(const enum encoding dec, char *restrict const buf,
-	      const size_t buflen, const char *restrict const p, va_list ap)
+	      const size_t buflen, ssize_t inlen,
+	      const char *const p, va_list ap)
 {
 	const struct b64_alphabet *alpha = &b64_alphabet[dec];
 	char *dest = buf;
@@ -139,7 +140,7 @@ base64_decode(const enum encoding dec, char *restrict const buf,
 			errno = EINVAL;
 			return -1;
 		}
-		while (*s) {
+		while (*s && (inlen == -1 || inlen > 0)) {
 			while (n < 4) {
 				char b = alpha->i64[(unsigned) *s++];
 				u <<= 6;
@@ -155,6 +156,11 @@ base64_decode(const enum encoding dec, char *restrict const buf,
 				u |= (unsigned) b;
 				if (!*s)
 					break;
+				if (inlen != -1) {
+					--inlen;
+					if (inlen == 0)
+						break;
+				}
 			}
 			if (n == 4) {
 				if (decode(&dest, buf, buflen, u, n-term) < 0) {
@@ -164,6 +170,8 @@ base64_decode(const enum encoding dec, char *restrict const buf,
 				n = 0;
 			}
 		}
+		if (inlen != -1 && inlen == 0)
+			break;
 	}
 	if (n) {
 		if (!alpha->padding)

src/hex.c

@@ -100,7 +100,8 @@ hex_encode(const enum encoding enc, char *restrict const buf,
 
 ssize_t
 hex_decode(const enum encoding dec, char *restrict const buf,
-	   const size_t buflen, const char *restrict const p, va_list ap)
+	   const size_t buflen, ssize_t n,
+	   const char *restrict const p, va_list ap)
 {
 	char *dest = buf;
 	unsigned char extranib = 0;
@@ -132,22 +133,30 @@ hex_decode(const enum encoding dec, char *restrict const buf,
 		errno = EINVAL;
 		return -1;
 	}
+	if (n != -1 && len > n)
+		len = n;
+
 	if ((len+1) >> 1 > buflen) {
 		errno = ENOMEM;
 		return -1;
 	}
-	if (len & 1)
+	if (len & 1) {
 		extranib = '0';
+		len++;
+	}
 
-	for (const char *s = p; s != vrt_magic_string_end;
+	for (const char *s = p; len > 0 && s != vrt_magic_string_end;
 	     s = va_arg(ap, const char *)) {
 		if (s == NULL || *s == '\0')
 			continue;
-		if (extranib)
+		if (extranib) {
 			*dest++ = hex2byte(extranib, *s++);
-		while (*s && *(s+1)) {
+			len -= 2;
+		}
+		while (len >= 2 && *s && *(s+1)) {
 			*dest++ = hex2byte(*s, *(s+1));
 			s += 2;
+			len -= 2;
 		}
 		extranib = *s;
 	}

src/id.c

@@ -64,8 +64,9 @@ id_encode(const enum encoding enc, char *restrict const buf,
 }
 
 ssize_t
-id_decode(const enum encoding enc, char *restrict const buf,
-	  const size_t buflen, const char *restrict const p, va_list ap)
+id_decode(const enum encoding enc,
+	  char *restrict const buf, const size_t buflen,
+	  ssize_t n, const char *restrict const p, va_list ap)
 {
 	char *dest = buf;
 	size_t len, outlen = 0;
@@ -78,6 +79,13 @@ id_decode(const enum encoding enc, char *restrict const buf,
 		if (s == NULL || *s == '\0')
 			continue;
 		len = strlen(s);
+		if (n >= 0) {
+			if (n == 0)
+				break;
+			if (len > n)
+				len = n;
+			n -= len;
+		}
 		if ((outlen += len) > buflen) {
 			errno = ENOMEM;
 			return -1;

src/vmod_blobcode.c

@@ -226,7 +226,7 @@ vmod_blob__init(VRT_CTX, struct vmod_blobcode_blob **blobp, const char *vcl_name
 
 	va_start(ap, p);
 	errno = 0;
-	len = func[dec].decode(dec, b->blob.priv, len, p, ap);
+	len = func[dec].decode(dec, b->blob.priv, len, -1, p, ap);
 	va_end(ap);
 
 	if (len == -1) {
@@ -325,10 +325,10 @@ vmod_blob__fini(struct vmod_blobcode_blob **blobp)
 
 /* Functions */
 
-VCL_BLOB __match_proto__(td_blobcode_decode)
-vmod_decode(VRT_CTX, VCL_ENUM decs, const char *p, ...) {
+static VCL_BLOB
+decode(VRT_CTX, VCL_INT n, VCL_ENUM decs, const char *restrict const p,
+       va_list ap) {
 	enum encoding dec = parse_encoding(decs);
-	va_list ap;
 	struct wb_s wb;
 	struct vmod_priv *b;
 	char *snap, *buf;
@@ -355,10 +355,8 @@ vmod_decode(VRT_CTX, VCL_ENUM decs, const char *p, ...) {
 	}
 	buf = wb_buf(&wb);
 
-	va_start(ap, p);
 	errno = 0;
-	len = func[dec].decode(dec, buf, wb_space(&wb), p, ap);
-	va_end(ap);
+	len = func[dec].decode(dec, buf, wb_space(&wb), n, p, ap);
 
 	if (len == -1) {
 		err_decode(ctx, p);
@@ -379,6 +377,30 @@ vmod_decode(VRT_CTX, VCL_ENUM decs, const char *p, ...) {
 	return b;
 }
 
+VCL_BLOB __match_proto__(td_blobcode_decode)
+vmod_decode(VRT_CTX, VCL_ENUM decs, const char *p, ...) {
+	va_list ap;
+	VCL_BLOB r;
+
+	va_start(ap, p);
+	r = decode(ctx, -1, decs, p, ap);
+	va_end(ap);
+
+	return (r);
+}
+
+VCL_BLOB __match_proto__(td_blobcode_decode_n)
+vmod_decode_n(VRT_CTX, VCL_INT n, VCL_ENUM decs, const char *p, ...) {
+	va_list ap;
+	VCL_BLOB r;
+
+	va_start(ap, p);
+	r = decode(ctx, n, decs, p, ap);
+	va_end(ap);
+
+	return (r);
+}
+
 VCL_STRING __match_proto__(td_blobcode_encode)
 vmod_encode(VRT_CTX, VCL_ENUM encs, VCL_BLOB b) {
 	enum encoding enc = parse_encoding(encs);
@@ -417,13 +439,14 @@ vmod_encode(VRT_CTX, VCL_ENUM encs, VCL_BLOB b) {
 	return wb_finish(&wb, NULL);
 }
 
-VCL_STRING __match_proto__(td_blobcode_transcode)
-vmod_transcode(VRT_CTX, VCL_ENUM decs, VCL_ENUM encs, const char *p, ...) {
+static VCL_STRING
+transcode(VRT_CTX, VCL_INT n, VCL_ENUM decs, VCL_ENUM encs,
+	  const char *restrict const p, va_list ap) {
 	enum encoding dec = parse_encoding(decs);
 	enum encoding enc = parse_encoding(encs);
 	struct wb_s wb;
 	ssize_t len;
-	va_list ap;
+	va_list aq;
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 	if (INIT_FINI(ctx)) {
@@ -435,19 +458,22 @@ vmod_transcode(VRT_CTX, VCL_ENUM decs, VCL_ENUM encs, const char *p, ...) {
 	AENC(dec);
 	AENC(enc);
 
-	/* Allocate space for the decoded blob on the stack */
-	va_start(ap, p);
-	size_t l = decode_l_va(dec, p, ap);
-	va_end(ap);
+	/*
+	 * Allocate space for the decoded blob on the stack
+	 * ignoring the limitation imposed by n
+	 */
+	va_copy(aq, ap);
+	size_t l = decode_l_va(dec, p, aq);
+	va_end(aq);
 	if (l == 0)
 		return "";
 	/* XXX: handle stack overflow? */
 	char buf[l];
 
-	va_start(ap, p);
 	errno = 0;
-	len = func[dec].decode(dec, buf, l, p, ap);
-	va_end(ap);
+	va_copy(aq, ap);
+	len = func[dec].decode(dec, buf, l, n, p, aq);
+	va_end(aq);
 
 	if (len == -1) {
 		err_decode(ctx, p);
@@ -459,9 +485,8 @@ vmod_transcode(VRT_CTX, VCL_ENUM decs, VCL_ENUM encs, const char *p, ...) {
 	 * legal, just return the concatenated string.
 	 */
 	if (enc == dec) {
-		va_start(ap, p);
-		VCL_STRING s = VRT_String(ctx->ws, NULL, p, ap);
-		va_end(ap);
+		VCL_STRING s;
+		s = VRT_String(ctx->ws, NULL, p, ap);
 		return s;
 	}
 
@@ -484,6 +509,32 @@ vmod_transcode(VRT_CTX, VCL_ENUM decs, VCL_ENUM encs, const char *p, ...) {
 	return wb_finish(&wb, NULL);
 }
 
+VCL_STRING __match_proto__(td_blobcode_transcode)
+vmod_transcode(VRT_CTX, VCL_ENUM decs, VCL_ENUM encs,
+	       const char *p, ...) {
+	va_list ap;
+	VCL_STRING r;
+
+	va_start(ap, p);
+	r = transcode(ctx, -1, decs, encs, p, ap);
+	va_end(ap);
+
+	return (r);
+}
+
+VCL_STRING __match_proto__(td_blobcode_transcode_n)
+vmod_transcode_n(VRT_CTX, VCL_INT n, VCL_ENUM decs, VCL_ENUM encs,
+	       const char *p, ...) {
+	va_list ap;
+	VCL_STRING r;
+
+	va_start(ap, p);
+	r = transcode(ctx, n, decs, encs, p, ap);
+	va_end(ap);
+
+	return (r);
+}
+
 VCL_STRING __match_proto__(td_blobcode_version)
 vmod_version(VRT_CTX __attribute__((unused)))
 {

src/vmod_blobcode.h

@@ -77,6 +77,7 @@ ssize_t encode_f(const enum encoding enc, char *restrict const buf,
  * dec: decoding enum (from parse_encoding.h)
  * buf: destination of the decoded data
  * buflen: maximum length available at buf
+ * inlen: maximum length to read or -1 to read up to \0
  * p, ap: strings obtained from a VCL STRING_LIST
  *
  * The regions pointed to by buf and any of the strings in p or ap MUST
@@ -93,7 +94,8 @@ ssize_t encode_f(const enum encoding enc, char *restrict const buf,
  */
 typedef
 ssize_t decode_f(const enum encoding dec, char *restrict const buf,
-		 const size_t buflen, const char *restrict const p, va_list ap);
+		 const size_t buflen, const ssize_t inlen,
+		 const char *restrict const p, va_list ap);
 
 /* id.c */
 len_f	 id_encode_l;

src/vmod_blobcode.vcc

@@ -144,6 +144,14 @@ Description
 Example
         ``blobcode.decode(decoding=BASE64, encoded="Zm9vYmFyYmF6")``
 
+$Function BLOB decode_n(INT n,
+			ENUM {IDENTITY, BASE64, BASE64URL,
+			BASE64URLNOPAD, HEX} decoding,
+			STRING_LIST encoded)
+
+Description
+	Same as ``decode()``, but only decode ``n`` characters.
+
 $Function STRING encode(ENUM {IDENTITY, BASE64, BASE64URL, BASE64URLNOPAD,
                               HEXUC, HEXLC} encoding, BLOB blob)
 
@@ -171,6 +179,16 @@ Example
 	``set req.http.Hex2Base64 = blobcode.transcode(decoding=HEX,``
                                     ``encoding=BASE64, encoded="666f6f");``
 
+$Function STRING transcode_n(INT n,
+			     ENUM {IDENTITY, BASE64, BASE64URL, BASE64URLNOPAD,
+                                   HEX} decoding,
+                             ENUM {IDENTITY, BASE64, BASE64URL, BASE64URLNOPAD,
+                                   HEXUC, HEXLC} encoding,
+                             STRING_LIST encoded)
+
+Description
+	Same as ``transcode()``, but only transcode ``n`` characters.
+
 $Function STRING version()
 
 Description