アドレスの検証

/**
 * Validates an input address and classifies it as a wallet, token account,
 * address requiring recipient verification, or invalid.
 *
 * @param inputAddress - The address to validate
 * @param rpc - Optional RPC client (defaults to mainnet)
 * @returns Classification result:
 *   - IS_WALLET: Valid wallet address
 *   - IS_TOKEN_ACCOUNT: Valid token account
 *   - USER_VERIFICATION: Require explicit review before sending SPL tokens
 *   - REJECT: Invalid address for transfers
 */
export async function validateAddress(
  inputAddress: Address,
  rpc: Rpc<GetAccountInfoApi> = defaultRpc
): Promise<ValidationResult> {
  const account = await fetchJsonParsedAccount(rpc, inputAddress);
  // Log the account data for demo
  console.log("\nAccount:", account);

  // Account doesn't exist onchain
  if (!account.exists) {
    // An unfunded PDA may belong to a smart wallet, but the address
    // alone cannot prove that its program can access a newly-created ATA.
    if (isOffCurveAddress(inputAddress)) {
      return {
        type: "USER_VERIFICATION",
        reason:
          "Unfunded PDA: confirm the recipient is using a smart wallet and controls this address"
      };
    }
    // On-curve = valid keypair address, treat as unfunded wallet
    return { type: "IS_WALLET" };
  }

  // Account exists, check program owner
  const owner = account.programAddress;

  // A System Program account can be a standard wallet or an off-curve smart
  // wallet. Require verification before automatically sending to the
  // latter.
  if (owner === SYSTEM_PROGRAM) {
    if (isOffCurveAddress(inputAddress)) {
      return {
        type: "USER_VERIFICATION",
        reason:
          "Off-curve System Program account: confirm recipient is using a smart wallet"
      };
    }
    return { type: "IS_WALLET" };
  }

  // Token Program or Token-2022, check if token account
  if (owner === TOKEN_PROGRAM || owner === TOKEN_2022_PROGRAM) {
    const accountType = (
      account.data as { parsedAccountMeta?: { type?: string } }
    ).parsedAccountMeta?.type;

    if (accountType === "account") {
      return { type: "IS_TOKEN_ACCOUNT" };
    }
    // Reject if not a token account (mint account)
    return {
      type: "REJECT",
      reason: "Not a token account"
    };
  }

  // An account owned by another program can be a smart wallet.
  return {
    type: "USER_VERIFICATION",
    reason:
      "Program-owned account: confirm the recipient is using a smart wallet"
  };
}

/**
 * Native SOL is only safe to send to a wallet. Any other account locks it.
 */
function canReceiveNativeSol(result: ValidationResult): boolean {
  return result.type === "IS_WALLET";
}

/**
 * SPL tokens can go to a wallet (via its ATA) or directly to a token account.
 */
function canReceiveSplToken(result: ValidationResult): boolean {
  return result.type === "IS_WALLET" || result.type === "IS_TOKEN_ACCOUNT";
}

// =============================================================================
// Examples
// =============================================================================