isValidWsSubscription function

dynamic isValidWsSubscription(WsSubScriptClient subscription)

Validate a WebSocket subscription to a script/address

Returns true if valid, or an error message string if invalid

Implementation

dynamic isValidWsSubscription(WsSubScriptClient subscription) {
  final scriptType = subscription.scriptType;
  final payload = subscription.payload;

  // Test for odd length
  if (payload.length % 2 != 0) {
    return 'Odd hex length: $payload';
  }

  // Test for valid hex
  if (!_validHexRegex.hasMatch(payload)) {
    return 'Invalid hex: "$payload". Payload must be lowercase hex string.';
  }

  // 20 bytes
  const supportedHashBytesP2pkhP2sh = 20;
  const supportedHashBytesP2pk = [33, 65];
  final payloadBytes = payload.length ~/ 2;

  switch (scriptType) {
    case 'p2pkh':
    case 'p2sh':
      // Test for length
      if (payloadBytes != supportedHashBytesP2pkhP2sh) {
        return 'Invalid length, expected 20 bytes but got $payloadBytes bytes';
      }
      return true;

    case 'p2pk':
      if (!supportedHashBytesP2pk.contains(payloadBytes)) {
        return 'Invalid length, expected one of [33, 65] but got $payloadBytes bytes';
      }
      return true;

    case 'other':
      // Only tests here are for odd length and valid hex, already performed
      return true;

    default:
      // Unsupported type
      return 'Invalid scriptType: $scriptType';
  }
}