mirror of
https://github.com/cypherstack/stack_wallet.git
synced 2024-11-17 17:57:40 +00:00
376 lines
9.9 KiB
Dart
376 lines
9.9 KiB
Dart
import 'dart:typed_data';
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import 'package:hex/hex.dart';
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import 'package:convert/convert.dart';
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// The Structure enum
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enum Structure {
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HasAmount,
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HasNFT,
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HasCommitmentLength,
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}
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// The Capability enum
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enum Capability {
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NoCapability,
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Mutable,
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Minting,
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}
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// Used as a "custom tuple" for the supporting functions of readCompactSize to return
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// a convenient data structure.
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class CompactSizeResult {
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final int amount;
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final int bytesRead;
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CompactSizeResult({required this.amount, required this.bytesRead});
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}
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// This class is a data structure representing the entire output, comprised of both the
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// normal Script pub key and the token data. We get this after we parse/unwrap the raw
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// output.
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class ParsedOutput {
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List<int>? script_pub_key;
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TokenOutputData? token_data;
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ParsedOutput({this.script_pub_key, this.token_data});
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}
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// This is equivalent to the Electron Cash python's "OutputData" in token.py.
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// Named here specifically as "TokenOutputData" to reflect the fact that
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// it is specifically for tokens, whereas the other class ParsedOutput represents
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// the entire output, comprised of both the normal Script pub key and the token data.
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class TokenOutputData {
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Uint8List? id;
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int? amount;
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Uint8List? commitment;
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Uint8List? bitfield; // A byte (Uint8List of length 1)
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// Constructor
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TokenOutputData({
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this.id,
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this.amount,
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this.commitment,
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this.bitfield,
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});
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// Get the "capability", see Capability enum.
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int getCapability() {
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if (bitfield != null) {
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return bitfield![0] & 0x0f;
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}
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return 0;
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}
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// functions to return attributes of the token bitfield.
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bool hasCommitmentLength() {
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if (bitfield != null) {
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return (bitfield![0] & 0x40) != 0;
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}
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return false;
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}
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bool hasAmount() {
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if (bitfield != null) {
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return (bitfield![0] & 0x10) != 0;
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}
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return false;
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}
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bool hasNFT() {
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if (bitfield != null) {
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return (bitfield![0] & 0x20) != 0;
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}
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return false;
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}
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// Functions to return specific attributes based on the Capability.
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bool isMintingNFT() {
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return hasNFT() && getCapability() == Capability.Minting.index;
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}
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bool isMutableNFT() {
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return hasNFT() && getCapability() == Capability.Mutable.index;
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}
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bool isImmutableNFT() {
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return hasNFT() && getCapability() == Capability.NoCapability.index;
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}
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// This function validates if the bitfield makes sense or violates known rules/logic.
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bool isValidBitfield() {
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if (bitfield == null) {
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return false;
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}
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int s = bitfield![0] & 0xf0;
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if (s >= 0x80 || s == 0x00) {
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return false;
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}
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if (bitfield![0] & 0x0f > 2) {
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return false;
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}
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if (!hasNFT() && !hasAmount()) {
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return false;
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}
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if (!hasNFT() && (bitfield![0] & 0x0f) != 0) {
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return false;
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}
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if (!hasNFT() && hasCommitmentLength()) {
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return false;
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}
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return true;
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}
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// The serialze and deserialize functions are the nuts and bolts of how we unpack
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// and pack outputs. These are called by the wrap and unwrap functions.
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int deserialize(Uint8List buffer, {int cursor = 0, bool strict = false}) {
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try {
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this.id = buffer.sublist(cursor, cursor + 32);
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cursor += 32;
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this.bitfield = Uint8List.fromList([buffer[cursor]]);
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cursor += 1;
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if (this.hasCommitmentLength()) {
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// Read the first byte to determine the length of the commitment data
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int commitmentLength = buffer[cursor];
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// Move cursor to the next byte
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cursor += 1;
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// Read 'commitmentLength' bytes for the commitment data
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this.commitment = buffer.sublist(cursor, cursor + commitmentLength);
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// Adjust the cursor by the length of the commitment data
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cursor += commitmentLength;
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} else {
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this.commitment = null;
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}
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if (this.hasAmount()) {
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// Use readCompactSize that returns CompactSizeResult
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CompactSizeResult result = readCompactSize(buffer, cursor, strict: strict);
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this.amount = result.amount;
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cursor += result.bytesRead;
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} else {
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this.amount = 0;
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}
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if (!this.isValidBitfield() ||
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(this.hasAmount() && this.amount == 0) ||
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(this.amount! < 0 || this.amount! > (1 << 63) - 1) ||
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(this.hasCommitmentLength() && this.commitment!.isEmpty) ||
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(this.amount! == 0 && !this.hasNFT())
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) {
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throw Exception('Unable to parse token data or token data is invalid');
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}
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return cursor; // Return the number of bytes read
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} catch (e) {
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throw Exception('Deserialization failed: $e');
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}
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}
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// Serialize method
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Uint8List serialize() {
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var buffer = BytesBuilder();
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// write ID and bitfield
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buffer.add(this.id!);
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buffer.addByte(this.bitfield![0]);
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// Write optional fields
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if (this.hasCommitmentLength()) {
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buffer.add(this.commitment!);
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}
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if (this.hasAmount()) {
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List<int> compactSizeBytes = writeCompactSize(this.amount!);
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buffer.add(compactSizeBytes);
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}
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return buffer.toBytes();
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}
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} //END OF OUTPUTDATA CLASS
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// The prefix byte is specified by the CashTokens spec.
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final List<int> PREFIX_BYTE = [0xef];
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// This function wraps a "normal" output together with token data.
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ParsedOutput wrap_spk(TokenOutputData? token_data, Uint8List script_pub_key) {
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ParsedOutput parsedOutput = ParsedOutput();
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if (token_data == null) {
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parsedOutput.script_pub_key = script_pub_key;
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return parsedOutput;
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}
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final buf = BytesBuilder();
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buf.add(PREFIX_BYTE);
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buf.add(token_data.serialize());
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buf.add(script_pub_key);
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parsedOutput.script_pub_key = buf.toBytes();
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parsedOutput.token_data = token_data;
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return parsedOutput;
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}
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// This function unwraps any output, either "normal" (containing no token data)
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// or an output with token data. If no token data, just the output is returned,
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// and if token data exists, both the output and token data are returned.
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// Note that the data returend in both cases in of ParsedOutput type, which
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// holds both the script pub key and token data.
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ParsedOutput unwrap_spk(Uint8List wrapped_spk) {
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ParsedOutput parsedOutput = ParsedOutput();
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if (wrapped_spk.isEmpty || wrapped_spk[0] != PREFIX_BYTE[0]) {
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parsedOutput.script_pub_key = wrapped_spk;
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return parsedOutput;
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}
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int read_cursor = 1; // Start after the PREFIX_BYTE
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TokenOutputData token_data = TokenOutputData();
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Uint8List wrapped_spk_without_prefix_byte;
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try {
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// Deserialize updates read_cursor by the number of bytes read
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wrapped_spk_without_prefix_byte= wrapped_spk.sublist(read_cursor);
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int bytesRead = token_data.deserialize(wrapped_spk_without_prefix_byte);
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read_cursor += bytesRead;
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parsedOutput.token_data = token_data;
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parsedOutput.script_pub_key = wrapped_spk.sublist(read_cursor);
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} catch (e) {
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// If unable to deserialize, return all bytes as the full scriptPubKey
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parsedOutput.script_pub_key = wrapped_spk;
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}
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return parsedOutput;
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}
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// Just a testing function which can be called in standalone fashion.
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// Replace "var1" with a hex string containing an output (script pub key)
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void testUnwrapSPK() {
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// Example Hex format string
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String var1 = "YOUR-SCRIPT-PUBKEY-AS-HEX-STRING-FOR-TESTING-GOES-HERE";
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// Convert the Hex string to Uint8List
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Uint8List wrapped_spk = Uint8List.fromList(HEX.decode(var1));
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// Call unwrap_spk
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ParsedOutput parsedOutput = unwrap_spk(wrapped_spk);
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print("Parsed Output: $parsedOutput");
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// Access token_data inside parsedOutput
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TokenOutputData? tokenData = parsedOutput.token_data;
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// Check if tokenData is null
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if (tokenData != null) {
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// Print specific fields
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if (tokenData.id != null) {
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print("ID: ${hex.encode(tokenData.id!)}"); // hex is imported
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} else {
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print("ID: null");
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}
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print ("amount of tokens");
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print (tokenData.amount);
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print("Is it an NFT?: ${tokenData.hasNFT()}");
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} else {
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print("Token data is null.");
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}
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} //end function
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// HELPER FUNCTIONS
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//These are part of a "length value " scheme where the length (and endianness) are given first
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// and inform the program of how many bytes to grab next. These are in turn used by the serialize
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// and deserialize functions.-
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CompactSizeResult readCompactSize(Uint8List buffer, int cursor, {bool strict = false}) {
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int bytesRead = 0; // Variable to count bytes read
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int val;
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try {
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val = buffer[cursor];
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cursor += 1;
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bytesRead += 1;
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int minVal;
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if (val == 253) {
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val = buffer.buffer.asByteData().getUint16(cursor, Endian.little);
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cursor += 2;
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bytesRead += 2;
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minVal = 253;
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} else if (val == 254) {
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val = buffer.buffer.asByteData().getUint32(cursor, Endian.little);
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cursor += 4;
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bytesRead += 4;
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minVal = 1 << 16;
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} else if (val == 255) {
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val = buffer.buffer.asByteData().getInt64(cursor, Endian.little);
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cursor += 8;
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bytesRead += 8;
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minVal = 1 << 32;
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} else {
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minVal = 0;
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}
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if (strict && val < minVal) {
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throw Exception("CompactSize is not minimally encoded");
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}
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return CompactSizeResult(amount: val, bytesRead: bytesRead);
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} catch (e) {
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throw Exception("attempt to read past end of buffer");
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}
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}
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Uint8List writeCompactSize(int size) {
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var buffer = ByteData(9); // Maximum needed size for compact size is 9 bytes
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if (size < 0) {
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throw Exception("attempt to write size < 0");
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} else if (size < 253) {
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return Uint8List.fromList([size]);
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} else if (size < (1 << 16)) {
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buffer.setUint8(0, 253);
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buffer.setUint16(1, size, Endian.little);
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return buffer.buffer.asUint8List(0, 3);
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} else if (size < (1 << 32)) {
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buffer.setUint8(0, 254);
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buffer.setUint32(1, size, Endian.little);
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return buffer.buffer.asUint8List(0, 5);
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} else if (size < (1 << 64)) {
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buffer.setUint8(0, 255);
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buffer.setInt64(1, size, Endian.little);
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return buffer.buffer.asUint8List(0, 9);
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} else {
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throw Exception("Size too large to represent as CompactSize");
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}
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}
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