wire: tlv base type handling.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

wire/fromwire.c

@@ -1,4 +1,5 @@
 #include "wire.h"
+#include <assert.h>
 #include <bitcoin/chainparams.h>
 #include <bitcoin/preimage.h>
 #include <bitcoin/pubkey.h>
@@ -86,6 +87,58 @@ u64 fromwire_u64(const u8 **cursor, size_t *max)
 	return be64_to_cpu(ret);
 }
 
+static u64 fromwire_tlv_uint(const u8 **cursor, size_t *max, size_t maxlen)
+{
+	u8 bytes[8];
+	size_t length;
+	be64 val;
+
+	assert(maxlen <= sizeof(bytes));
+
+	/* BOLT-EXPERIMENTAL #1:
+	 *
+	 * - if `length` is not exactly equal to that required for the
+	 *   known encoding for `type`:
+	 *      - MUST fail to parse the `tlv_stream`.
+	 */
+	length = *max;
+	if (length > maxlen) {
+		fromwire_fail(cursor, max);
+		return 0;
+	}
+
+	memset(bytes, 0, sizeof(bytes));
+	fromwire(cursor, max, bytes + sizeof(bytes) - length, length);
+
+	/* BOLT-EXPERIMENTAL #1:
+	 * - if variable-length fields within the known encoding for `type` are
+	 *   not minimal:
+	 *    - MUST fail to parse the `tlv_stream`.
+	 */
+	if (length > 0 && bytes[sizeof(bytes) - length] == 0) {
+		fromwire_fail(cursor, max);
+		return 0;
+	}
+	BUILD_ASSERT(sizeof(val) == sizeof(bytes));
+	memcpy(&val, bytes, sizeof(bytes));
+	return be64_to_cpu(val);
+}
+
+u16 fromwire_tu16(const u8 **cursor, size_t *max)
+{
+	return fromwire_tlv_uint(cursor, max, 2);
+}
+
+u32 fromwire_tu32(const u8 **cursor, size_t *max)
+{
+	return fromwire_tlv_uint(cursor, max, 4);
+}
+
+u64 fromwire_tu64(const u8 **cursor, size_t *max)
+{
+	return fromwire_tlv_uint(cursor, max, 8);
+}
+
 void fromwire_double(const u8 **cursor, size_t *max, double *ret)
 {
 	fromwire(cursor, max, ret, sizeof(*ret));

wire/towire.c

@@ -44,6 +44,38 @@ void towire_u64(u8 **pptr, u64 v)
 	towire(pptr, &l, sizeof(l));
 }
 
+static void towire_tlv_uint(u8 **pptr, u64 v)
+{
+	u8 bytes[8];
+	size_t num_zeroes;
+	be64 val;
+
+	val = cpu_to_be64(v);
+	BUILD_ASSERT(sizeof(val) == sizeof(bytes));
+	memcpy(bytes, &val, sizeof(bytes));
+
+	for (num_zeroes = 0; num_zeroes < sizeof(bytes); num_zeroes++)
+		if (bytes[num_zeroes] != 0)
+			break;
+
+	towire(pptr, bytes + num_zeroes, sizeof(bytes) - num_zeroes);
+}
+
+void towire_tu16(u8 **pptr, u16 v)
+{
+	return towire_tlv_uint(pptr, v);
+}
+
+void towire_tu32(u8 **pptr, u32 v)
+{
+	return towire_tlv_uint(pptr, v);
+}
+
+void towire_tu64(u8 **pptr, u64 v)
+{
+	return towire_tlv_uint(pptr, v);
+}
+
 void towire_double(u8 **pptr, const double *v)
 {
 	towire(pptr, v, sizeof(*v));

wire/wire.h

@@ -66,6 +66,9 @@ void towire_u8(u8 **pptr, u8 v);
 void towire_u16(u8 **pptr, u16 v);
 void towire_u32(u8 **pptr, u32 v);
 void towire_u64(u8 **pptr, u64 v);
+void towire_tu16(u8 **pptr, u16 v);
+void towire_tu32(u8 **pptr, u32 v);
+void towire_tu64(u8 **pptr, u64 v);
 void towire_double(u8 **pptr, const double *v);
 void towire_pad(u8 **pptr, size_t num);
 void towire_bool(u8 **pptr, bool v);
@@ -84,6 +87,9 @@ u8 fromwire_u8(const u8 **cursor, size_t *max);
 u16 fromwire_u16(const u8 **cursor, size_t *max);
 u32 fromwire_u32(const u8 **cursor, size_t *max);
 u64 fromwire_u64(const u8 **cursor, size_t *max);
+u16 fromwire_tu16(const u8 **cursor, size_t *max);
+u32 fromwire_tu32(const u8 **cursor, size_t *max);
+u64 fromwire_tu64(const u8 **cursor, size_t *max);
 void fromwire_double(const u8 **cursor, size_t *max, double *v);
 bool fromwire_bool(const u8 **cursor, size_t *max);
 u64 fromwire_bigsize(const u8 **cursor, size_t *max);