Add lcli tool for checking deposit data (#940)

* Add check-deposit-data tool

* Update help text

* Update function name

lcli/src/check_deposit_data.rs

@@ -0,0 +1,31 @@
+use crate::helpers::{parse_hex_bytes, parse_u64};
+use clap::ArgMatches;
+use deposit_contract::{decode_eth1_tx_data, DEPOSIT_DATA_LEN};
+use tree_hash::TreeHash;
+use types::EthSpec;
+
+pub fn run<T: EthSpec>(matches: &ArgMatches) -> Result<(), String> {
+    let rlp_bytes = parse_hex_bytes(matches, "deposit-data")?;
+    let amount = parse_u64(matches, "deposit-amount")?;
+
+    if rlp_bytes.len() != DEPOSIT_DATA_LEN {
+        return Err(format!(
+            "The given deposit-data is {} bytes, expected {}",
+            rlp_bytes.len(),
+            DEPOSIT_DATA_LEN
+        ));
+    }
+
+    let (deposit_data, root) = decode_eth1_tx_data(&rlp_bytes, amount)
+        .map_err(|e| format!("Invalid deposit data bytes: {:?}", e))?;
+
+    let expected_root = deposit_data.tree_hash_root();
+    if root != expected_root {
+        return Err(format!(
+            "Deposit data root is invalid. Expected {:?}, but got {:?}. Perhaps the amount is incorrect?",
+            expected_root, root
+        ));
+    }
+
+    Ok(())
+}

lcli/src/helpers.rs

@@ -83,3 +83,16 @@ pub fn parse_fork_opt(matches: &ArgMatches, name: &'static str) -> Result<Option
         })
         .transpose()
 }
+
+pub fn parse_hex_bytes(matches: &ArgMatches, name: &'static str) -> Result<Vec<u8>, String> {
+    matches
+        .value_of(name)
+        .ok_or_else(|| format!("{} not specified", name))
+        .and_then(|val| {
+            if val.starts_with("0x") {
+                hex::decode(&val[2..]).map_err(|e| format!("Unable to parse {}: {:?}", name, e))
+            } else {
+                Err(format!("Unable to parse {}, must have 0x prefix", name))
+            }
+        })
+}

lcli/src/main.rs

@@ -2,6 +2,7 @@
 extern crate log;
 
 mod change_genesis_time;
+mod check_deposit_data;
 mod deploy_deposit_contract;
 mod eth1_genesis;
 mod helpers;
@@ -359,6 +360,29 @@ fn main() {
                               optimization for nodes, please do it."),
                 )
         )
+        .subcommand(
+            SubCommand::with_name("check-deposit-data")
+                .about(
+                    "Checks the integrity of some deposit data.",
+                )
+                .arg(
+                    Arg::with_name("deposit-amount")
+                        .index(1)
+                        .value_name("GWEI")
+                        .takes_value(true)
+                        .required(true)
+                        .help("The amount (in Gwei) that was deposited"),
+                )
+                .arg(
+                    Arg::with_name("deposit-data")
+                        .index(2)
+                        .value_name("HEX")
+                        .takes_value(true)
+                        .required(true)
+                        .help("A 0x-prefixed hex string of the deposit data. Should include the
+                            function signature."),
+                )
+        )
         .get_matches();
 
     macro_rules! run_with_spec {
@@ -445,6 +469,8 @@ fn run<T: EthSpec>(env_builder: EnvironmentBuilder<T>, matches: &ArgMatches) {
             .unwrap_or_else(|e| error!("Failed to run change-genesis-time command: {}", e)),
         ("new-testnet", Some(matches)) => new_testnet::run::<T>(matches)
             .unwrap_or_else(|e| error!("Failed to run new_testnet command: {}", e)),
+        ("check-deposit-data", Some(matches)) => check_deposit_data::run::<T>(matches)
+            .unwrap_or_else(|e| error!("Failed to run check-deposit-data command: {}", e)),
         (other, _) => error!("Unknown subcommand {}. See --help.", other),
     }
 }