Add block header serialization binding

Author: stringintech

kernel/block_header.go

@@ -83,3 +83,17 @@ func (bh *BlockHeader) Version() int32 {
 func (bh *BlockHeader) Nonce() uint32 {
 	return uint32(C.btck_block_header_get_nonce((*C.btck_BlockHeader)(bh.ptr)))
 }
+
+// Bytes returns the consensus serialized representation of the block header.
+//
+// Returns an error if the serialization fails.
+func (bh *BlockHeader) Bytes() ([]byte, error) {
+	buf := make([]byte, 80)
+	if C.btck_block_header_to_bytes(
+		(*C.btck_BlockHeader)(bh.ptr),
+		(*C.uchar)(unsafe.Pointer(unsafe.SliceData(buf))),
+	) != 0 {
+		return nil, &SerializationError{"Failed to serialize block header"}
+	}
+	return buf, nil
+}

kernel/block_header_test.go

@@ -120,4 +120,17 @@ func TestBlockHeader(t *testing.T) {
 			t.Errorf("Expected nonce %d, got %d", expectedNonce, nonce)
 		}
 	})
+
+	t.Run("Bytes", func(t *testing.T) {
+		serialized, err := header.Bytes()
+		if err != nil {
+			t.Fatalf("Bytes() error = %v", err)
+		}
+		if len(serialized) != 80 {
+			t.Fatalf("Expected 80 bytes, got %d", len(serialized))
+		}
+		if hex.EncodeToString(serialized) != genesisHeaderHex {
+			t.Errorf("Serialized header doesn't match original.\nExpected: %s\nGot: %s", genesisHeaderHex, hex.EncodeToString(serialized))
+		}
+	})
 }