rpc.rs 10.9 KB
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use bitcoin::blockdata::block::BlockHeader;
use bitcoin::network::serialize::serialize;
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use bitcoin::util::hash::Sha256dHash;
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use crossbeam;
use crypto::digest::Digest;
use crypto::sha2::Sha256;
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use itertools;
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use serde_json::{from_str, Number, Value};
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use std::collections::HashMap;
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use std::io::{BufRead, BufReader, Write};
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use std::net::{SocketAddr, TcpListener, TcpStream};
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use std::sync::mpsc::{sync_channel, Receiver, SyncSender};
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use query::{Query, Status};
use index::FullHash;
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use util;
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error_chain!{}

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// TODO: Sha256dHash should be a generic hash-container (since script hash is single SHA256)
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fn hash_from_value(val: Option<&Value>) -> Result<Sha256dHash> {
    let script_hash = val.chain_err(|| "missing hash")?;
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    let script_hash = script_hash.as_str().chain_err(|| "non-string hash")?;
    let script_hash = Sha256dHash::from_hex(script_hash).chain_err(|| "non-hex hash")?;
    Ok(script_hash)
}

fn history_from_status(status: &Status) -> Vec<(u32, Sha256dHash)> {
    let mut txns_map = HashMap::<Sha256dHash, u32>::new();
    for f in &status.funding {
        txns_map.insert(f.txn_id, f.height);
    }
    for s in &status.spending {
        txns_map.insert(s.txn_id, s.height);
    }
    let mut txns: Vec<(u32, Sha256dHash)> =
        txns_map.into_iter().map(|item| (item.1, item.0)).collect();
    txns.sort();
    txns
}

fn hash_from_status(status: &Status) -> Option<FullHash> {
    let txns = history_from_status(status);
    if txns.is_empty() {
        return None;
    }

    let mut hash = FullHash::default();
    let mut sha2 = Sha256::new();
    for (height, txn_id) in txns {
        let part = format!("{}:{}:", txn_id.be_hex_string(), height);
        sha2.input(part.as_bytes());
    }
    sha2.result(&mut hash);
    Some(hash)
}

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fn format_header(header: &BlockHeader, height: usize) -> Value {
    json!({
        "block_height": height,
        "version": header.version,
        "prev_block_hash": header.prev_blockhash.be_hex_string(),
        "merkle_root": header.merkle_root.be_hex_string(),
        "timestamp": header.time,
        "bits": header.bits,
        "nonce": header.nonce
    })
}

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struct Handler<'a> {
    query: &'a Query<'a>,
}

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impl<'a> Handler<'a> {
    fn blockchain_headers_subscribe(&self) -> Result<Value> {
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        let entry = self.query
            .get_best_header()
            .chain_err(|| "no headers found")?;
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        Ok(format_header(entry.header(), entry.height()))
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    }
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    fn server_version(&self) -> Result<Value> {
        Ok(json!(["LES 0.1.0", "1.2"]))
    }
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    fn server_banner(&self) -> Result<Value> {
        Ok(json!("Welcome to Local Electrum Server!\n"))
    }
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    fn server_donation_address(&self) -> Result<Value> {
        Ok(json!("No, thanks :)\n"))
    }
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    fn server_peers_subscribe(&self) -> Result<Value> {
        Ok(json!([]))
    }
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    fn mempool_get_fee_histogram(&self) -> Result<Value> {
        Ok(json!([])) // TODO: consult with actual mempool
    }
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    fn blockchain_block_get_chunk(&self, params: &[Value]) -> Result<Value> {
        const CHUNK_SIZE: usize = 2016;
        let index = params.get(0).chain_err(|| "missing index")?;
        let index = index.as_u64().chain_err(|| "non-number index")? as usize;
        let heights: Vec<usize> = (0..CHUNK_SIZE).map(|h| index * CHUNK_SIZE + h).collect();
        let headers = self.query.get_headers(&heights);
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        let result = itertools::join(
            headers
                .into_iter()
                .map(|x| util::hexlify(&serialize(&x).unwrap())),
            "",
        );
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        Ok(json!(result))
    }

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    fn blockchain_block_get_header(&self, params: &[Value]) -> Result<Value> {
        let height = params.get(0).chain_err(|| "missing height")?;
        let height = height.as_u64().chain_err(|| "non-number height")? as usize;
        let headers = self.query.get_headers(&vec![height]);
        Ok(json!(format_header(&headers[0], height)))
    }

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    fn blockchain_estimatefee(&self, _params: &[Value]) -> Result<Value> {
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        Ok(json!(1e-5)) // TODO: consult with actual mempool
    }
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    fn blockchain_relayfee(&self) -> Result<Value> {
        Ok(json!(1e-5)) // TODO: consult with actual node
    }

    fn blockchain_scripthash_subscribe(&self, params: &[Value]) -> Result<Value> {
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        let script_hash = hash_from_value(params.get(0)).chain_err(|| "bad script_hash")?;
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        let status = self.query.status(&script_hash[..]);

        Ok(match hash_from_status(&status) {
            Some(hash) => Value::String(util::hexlify(&hash)),
            None => Value::Null,
        })
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    }
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    fn blockchain_scripthash_get_balance(&self, params: &[Value]) -> Result<Value> {
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        let script_hash = hash_from_value(params.get(0)).chain_err(|| "bad script_hash")?;
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        let status = self.query.status(&script_hash[..]);
        Ok(json!({ "confirmed": status.balance })) // TODO: "unconfirmed"
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    }
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    fn blockchain_scripthash_get_history(&self, params: &[Value]) -> Result<Value> {
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        let script_hash = hash_from_value(params.get(0)).chain_err(|| "bad script_hash")?;
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        let status = self.query.status(&script_hash[..]);
        Ok(json!(Value::Array(
            history_from_status(&status)
                .into_iter()
                .map(|item| json!({"height": item.0, "tx_hash": item.1.be_hex_string()}))
                .collect()
        )))
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    }
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    fn blockchain_transaction_get(&self, params: &[Value]) -> Result<Value> {
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        // TODO: handle 'verbose' param
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        let tx_hash = hash_from_value(params.get(0)).chain_err(|| "bad tx_hash")?;
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        let tx_hex = util::hexlify(&self.query.get_tx(&tx_hash));
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        Ok(json!(tx_hex))
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    }

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    fn blockchain_transaction_get_merkle(&self, params: &[Value]) -> Result<Value> {
        let tx_hash = hash_from_value(params.get(0)).chain_err(|| "bad tx_hash")?;
        let height = params.get(1).chain_err(|| "missing height")?;
        let height = height.as_u64().chain_err(|| "non-number height")? as usize;
        let (merkle, pos) = self.query
            .get_merkle_proof(&tx_hash, height)
            .chain_err(|| "cannot create merkle proof")?;
        let merkle: Vec<String> = merkle
            .into_iter()
            .map(|txid| txid.be_hex_string())
            .collect();
        Ok(json!({
                "block_height": height,
                "merkle": merkle,
                "pos": pos}))
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    }
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    fn handle_command(&self, method: &str, params: &[Value], id: &Number) -> Result<Value> {
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        let result = match method {
            "blockchain.headers.subscribe" => self.blockchain_headers_subscribe(),
            "server.version" => self.server_version(),
            "server.banner" => self.server_banner(),
            "server.donation_address" => self.server_donation_address(),
            "server.peers.subscribe" => self.server_peers_subscribe(),
            "mempool.get_fee_histogram" => self.mempool_get_fee_histogram(),
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            "blockchain.block.get_chunk" => self.blockchain_block_get_chunk(&params),
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            "blockchain.block.get_header" => self.blockchain_block_get_header(&params),
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            "blockchain.estimatefee" => self.blockchain_estimatefee(&params),
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            "blockchain.relayfee" => self.blockchain_relayfee(),
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            "blockchain.scripthash.subscribe" => self.blockchain_scripthash_subscribe(&params),
            "blockchain.scripthash.get_balance" => self.blockchain_scripthash_get_balance(&params),
            "blockchain.scripthash.get_history" => self.blockchain_scripthash_get_history(&params),
            "blockchain.transaction.get" => self.blockchain_transaction_get(&params),
            "blockchain.transaction.get_merkle" => self.blockchain_transaction_get_merkle(&params),
            &_ => bail!("unknown method {} {:?}", method, params),
        }?;
        let reply = json!({"jsonrpc": "2.0", "id": id, "result": result});
        Ok(reply)
    }

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    pub fn run(self, mut stream: TcpStream, addr: SocketAddr, chan: &Channel) -> Result<()> {
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        let mut reader = BufReader::new(stream
            .try_clone()
            .chain_err(|| "failed to clone TcpStream")?);
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        let tx = chan.sender();
        crossbeam::scope(|scope| {
            scope.spawn(|| loop {
                let mut line = String::new();
                line.clear();
                reader
                    .read_line(&mut line)
                    .expect("failed to read a request");
                if line.is_empty() {
                    tx.send(Message::Done).expect("channel closed");
                    break;
                } else {
                    tx.send(Message::Request(line)).expect("channel closed");
                }
            });

            let rx = chan.receiver();
            loop {
                let msg = rx.recv().chain_err(|| "channel closed")?;
                match msg {
                    Message::Request(line) => {
                        let cmd: Value = from_str(&line).chain_err(|| "invalid JSON format")?;

                        let reply = match (cmd.get("method"), cmd.get("params"), cmd.get("id")) {
                            (
                                Some(&Value::String(ref method)),
                                Some(&Value::Array(ref params)),
                                Some(&Value::Number(ref id)),
                            ) => self.handle_command(method, params, id)?,
                            _ => bail!("invalid command: {}", cmd),
                        };

                        info!("[{}] {}", addr, cmd);
                        debug!("reply: {}", reply);
                        let line = reply.to_string() + "\n";
                        stream
                            .write_all(line.as_bytes())
                            .chain_err(|| "failed to send response")?;
                    }
                    Message::Block(blockhash) => info!("block {} found", blockhash),
                    Message::Done => break,
                }
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            }
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            Ok(())
        })
    }
}

pub enum Message {
    Request(String),
    Block(Sha256dHash),
    Done,
}

pub struct Channel {
    tx: SyncSender<Message>,
    rx: Receiver<Message>,
}

impl Channel {
    pub fn new() -> Channel {
        let (tx, rx) = sync_channel(0);
        Channel { tx, rx }
    }

    pub fn sender(&self) -> SyncSender<Message> {
        self.tx.clone()
    }

    pub fn receiver(&self) -> &Receiver<Message> {
        &self.rx
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    }
}

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pub fn serve(addr: &str, query: &Query, mut chan: Channel) {
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    let listener = TcpListener::bind(addr).unwrap();
    info!("RPC server running on {}", addr);
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    loop {
        let (stream, addr) = listener.accept().unwrap();
        info!("[{}] connected peer", addr);
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        let handler = Handler { query };
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        match handler.run(stream, addr, &mut chan) {
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            Ok(()) => info!("[{}] disconnected peer", addr),
            Err(ref e) => {
                error!("[{}] {}", addr, e);
                for e in e.iter().skip(1) {
                    error!("caused by: {}", e);
                }
            }
        }
    }
}