Querying the Local Bitcoin Blockchain with C# .NET

Bitcoin, Blockchain / By

To query the local Bitcoin blockchain in C# .NET, you can either use a library that communicates with the local Bitcoin daemon via JSON-RPC or directly query the blockchain data stored on disk. If the daemon is running on the same machine, using a library like NBitcoin and JSON-RPC is a good option as it is simple and easy to use. If you need more flexibility and don’t want to rely on the daemon being running, directly querying the blockchain data using NBitcoin is a good choice but it can be slower and more complex.

If you’re working with Bitcoin in C# .NET and you want to query the local Bitcoin blockchain, there are a few options available. In this article, we’ll explore two approaches for querying the local blockchain, and the advantages and disadvantages of each.

Problem Formulation

The problem we’re trying to solve is how to query the local Bitcoin blockchain in C# .NET. We want to be able to check the balance of a given Bitcoin address using only the locally stored blockchain (downloaded via Bitcoin Core). We want to be able to do this offline, without needing access to the network.

Method 1

Using a Library to Query the Daemon One approach is to use a library that communicates with the local Bitcoin daemon via JSON-RPC. This approach is similar to using a web API, but instead of sending HTTP requests to a remote server, we’re sending them to a local daemon that’s running on our machine.

Here’s an example of how to check the balance of a Bitcoin address using NBitcoin and JSON-RPC:

using NBitcoin.RPC;

public decimal CheckBalance(BitcoinPubKeyAddress address)
{
    var rpc = new RPCClient("rpcuser", "rpcpassword", "http://localhost:8332/");
    var unspentCoins = rpc.ListUnspent()
        .Where(x => x.Address == address)
        .ToList();
    decimal balance = unspentCoins.Sum(x => x.Amount.ToDecimal(MoneyUnit.BTC));
    return balance;
}

This code uses the ListUnspent method to get a list of unspent coins for the given address, and then sums up the amounts to get the balance.

One advantage of this approach is that it’s very simple to use. The NBitcoin library abstracts away most of the details of communicating with the daemon, so you don’t need to worry about things like HTTP requests or JSON parsing.

However, one disadvantage of this approach is that it requires the Bitcoin daemon to be running on the same machine. If the daemon isn’t running, or if it’s running on a different machine, this approach won’t work.

Method 2

Directly Querying the Blockchain Data Another approach is to query the blockchain data stored on disk directly. This approach is more complex than using a library to query the daemon, but it’s also more flexible and doesn’t require the daemon to be running.

Here’s an example of how to check the balance of a Bitcoin address by directly querying the blockchain data using NBitcoin:

using NBitcoin;
using NBitcoin.Protocol;

public decimal CheckBalanceLocal(BitcoinPubKeyAddress address)
{
    var node = Node.ConnectToLocal(Network.Main);
    node.VersionHandshake();
    var chain = node.GetChain();

    var store = new BlockStore(@"F:\Program Files\Bitcoin\Cache\blocks", Network.Main);
    var index = new IndexedBlockStore(new InMemoryNoSqlRepository(), store);

    var headers = chain.ToEnumerable(false).ToArray();
    var balance = (
        from header in headers
        select index.Get(header.HashBlock)
        into block
        from tx in block.Transactions
        from txout in tx.Outputs
        where txout.ScriptPubKey.GetDestinationAddress(Network.Main) == address
        select txout.Value.ToDecimal(MoneyUnit.BTC)).Sum();

    return balance;
}

This code connects to a local Bitcoin node, gets the blockchain data, and then iterates over all of the transactions in the blockchain to find the unspent outputs for the given address. This approach doesn’t require the Bitcoin daemon to be running, and it allows you to search for all transactions that involve a particular address, not just the unspent outputs.

However, one disadvantage of this approach is that it can be slow. Querying the entire blockchain can take a long time, especially if you’re doing it on a machine with limited resources. Additionally, this approach requires a lot more code than the previous approach, and it can be more difficult to understand and maintain.

Conclusion

In conclusion, there are a few different ways to query the local Bitcoin blockchain in C# .NET. The best approach for you will depend on your specific needs and requirements. If you just need to check the balance of a given address and the daemon is running on the same machine, using a library like NBitcoin and JSON-RPC is a good option. If you need more flexibility and don’t want to rely on the daemon being running, directly querying the blockchain data using NBitcoin is a good choice, but be aware that it can be slower and more complex.

References and further reading:

  • https://stackoverflow.com/questions/41027747/query-local-bitcoin-blockchain-with-c-sharp-net
  • https://chat.openai.com

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