Add EF launchpad import (#1381)

## Issue Addressed

NA

## Proposed Changes

Adds an integration for keys generated via https://github.com/ethereum/eth2.0-deposit (In reality keys are *actually* generated here: https://github.com/ethereum/eth2.0-deposit-cli).

## Additional Info

NA

## TODO

- [x] Docs
- [x] Tests

Co-authored-by: Michael Sproul <michael@sigmaprime.io>

account_manager/src/validator/import.rs

@@ -0,0 +1,214 @@
+use crate::{common::ensure_dir_exists, VALIDATOR_DIR_FLAG};
+use account_utils::{
+    eth2_keystore::Keystore,
+    read_password_from_user,
+    validator_definitions::{
+        recursively_find_voting_keystores, ValidatorDefinition, ValidatorDefinitions,
+        CONFIG_FILENAME,
+    },
+};
+use clap::{App, Arg, ArgMatches};
+use std::fs;
+use std::path::PathBuf;
+use std::thread::sleep;
+use std::time::Duration;
+
+pub const CMD: &str = "import";
+pub const KEYSTORE_FLAG: &str = "keystore";
+pub const DIR_FLAG: &str = "directory";
+pub const STDIN_PASSWORD_FLAG: &str = "stdin-passwords";
+
+pub const PASSWORD_PROMPT: &str = "Enter the keystore password, or press enter to omit it:";
+pub const KEYSTORE_REUSE_WARNING: &str = "DO NOT USE THE ORIGINAL KEYSTORES TO VALIDATE WITH \
+                                          ANOTHER CLIENT, OR YOU WILL GET SLASHED.";
+
+pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
+    App::new(CMD)
+        .about(
+            "Imports one or more EIP-2335 passwords into a Lighthouse VC directory, \
+            requesting passwords interactively. The directory flag provides a convenient \
+            method for importing a directory of keys generated by the eth2-deposit-cli \
+            Python utility.",
+        )
+        .arg(
+            Arg::with_name(KEYSTORE_FLAG)
+                .long(KEYSTORE_FLAG)
+                .value_name("KEYSTORE_PATH")
+                .help("Path to a single keystore to be imported.")
+                .conflicts_with(DIR_FLAG)
+                .required_unless(DIR_FLAG)
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name(DIR_FLAG)
+                .long(DIR_FLAG)
+                .value_name("KEYSTORES_DIRECTORY")
+                .help(
+                    "Path to a directory which contains zero or more keystores \
+                    for import. This directory and all sub-directories will be \
+                    searched and any file name which contains 'keystore' and \
+                    has the '.json' extension will be attempted to be imported.",
+                )
+                .conflicts_with(KEYSTORE_FLAG)
+                .required_unless(KEYSTORE_FLAG)
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name(VALIDATOR_DIR_FLAG)
+                .long(VALIDATOR_DIR_FLAG)
+                .value_name("VALIDATOR_DIRECTORY")
+                .help(
+                    "The path where the validator directories will be created. \
+                    Defaults to ~/.lighthouse/validators",
+                )
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name(STDIN_PASSWORD_FLAG)
+                .long(STDIN_PASSWORD_FLAG)
+                .help("If present, read passwords from stdin instead of tty."),
+        )
+}
+
+pub fn cli_run(matches: &ArgMatches) -> Result<(), String> {
+    let keystore: Option<PathBuf> = clap_utils::parse_optional(matches, KEYSTORE_FLAG)?;
+    let keystores_dir: Option<PathBuf> = clap_utils::parse_optional(matches, DIR_FLAG)?;
+    let validator_dir = clap_utils::parse_path_with_default_in_home_dir(
+        matches,
+        VALIDATOR_DIR_FLAG,
+        PathBuf::new().join(".lighthouse").join("validators"),
+    )?;
+    let stdin_password = matches.is_present(STDIN_PASSWORD_FLAG);
+
+    ensure_dir_exists(&validator_dir)?;
+
+    let mut defs = ValidatorDefinitions::open_or_create(&validator_dir)
+        .map_err(|e| format!("Unable to open {}: {:?}", CONFIG_FILENAME, e))?;
+
+    // Collect the paths for the keystores that should be imported.
+    let keystore_paths = match (keystore, keystores_dir) {
+        (Some(keystore), None) => vec![keystore],
+        (None, Some(keystores_dir)) => {
+            let mut keystores = vec![];
+
+            recursively_find_voting_keystores(&keystores_dir, &mut keystores)
+                .map_err(|e| format!("Unable to search {:?}: {:?}", keystores_dir, e))?;
+
+            if keystores.is_empty() {
+                eprintln!("No keystores found in {:?}", keystores_dir);
+                return Ok(());
+            }
+
+            keystores
+        }
+        _ => {
+            return Err(format!(
+                "Must supply either --{} or --{}",
+                KEYSTORE_FLAG, DIR_FLAG
+            ))
+        }
+    };
+
+    eprintln!("WARNING: {}", KEYSTORE_REUSE_WARNING);
+
+    // For each keystore:
+    //
+    // - Obtain the keystore password, if the user desires.
+    // - Copy the keystore into the `validator_dir`.
+    // - Add the keystore to the validator definitions file.
+    //
+    // Skip keystores that already exist, but exit early if any operation fails.
+    let mut num_imported_keystores = 0;
+    for src_keystore in &keystore_paths {
+        let keystore = Keystore::from_json_file(src_keystore)
+            .map_err(|e| format!("Unable to read keystore JSON {:?}: {:?}", src_keystore, e))?;
+
+        eprintln!("");
+        eprintln!("Keystore found at {:?}:", src_keystore);
+        eprintln!("");
+        eprintln!(" - Public key: 0x{}", keystore.pubkey());
+        eprintln!(" - UUID: {}", keystore.uuid());
+        eprintln!("");
+        eprintln!(
+            "If you enter the password it will be stored as plain-text in {} so that it is not \
+             required each time the validator client starts.",
+            CONFIG_FILENAME
+        );
+
+        let password_opt = loop {
+            eprintln!("");
+            eprintln!("{}", PASSWORD_PROMPT);
+
+            let password = read_password_from_user(stdin_password)?;
+
+            if password.as_ref().is_empty() {
+                eprintln!("Continuing without password.");
+                sleep(Duration::from_secs(1)); // Provides nicer UX.
+                break None;
+            }
+
+            match keystore.decrypt_keypair(password.as_ref()) {
+                Ok(_) => {
+                    eprintln!("Password is correct.");
+                    eprintln!("");
+                    sleep(Duration::from_secs(1)); // Provides nicer UX.
+                    break Some(password);
+                }
+                Err(eth2_keystore::Error::InvalidPassword) => {
+                    eprintln!("Invalid password");
+                }
+                Err(e) => return Err(format!("Error whilst decrypting keypair: {:?}", e)),
+            }
+        };
+
+        // The keystore is placed in a directory that matches the name of the public key. This
+        // provides some loose protection against adding the same keystore twice.
+        let dest_dir = validator_dir.join(format!("0x{}", keystore.pubkey()));
+        if dest_dir.exists() {
+            eprintln!(
+                "Skipping import of keystore for existing public key: {:?}",
+                src_keystore
+            );
+            continue;
+        }
+
+        fs::create_dir_all(&dest_dir)
+            .map_err(|e| format!("Unable to create import directory: {:?}", e))?;
+
+        // Retain the keystore file name, but place it in the new directory.
+        let dest_keystore = src_keystore
+            .file_name()
+            .and_then(|file_name| file_name.to_str())
+            .map(|file_name_str| dest_dir.join(file_name_str))
+            .ok_or_else(|| format!("Badly formatted file name: {:?}", src_keystore))?;
+
+        // Copy the keystore to the new location.
+        fs::copy(&src_keystore, &dest_keystore)
+            .map_err(|e| format!("Unable to copy keystore: {:?}", e))?;
+
+        eprintln!("Successfully imported keystore.");
+        num_imported_keystores += 1;
+
+        let validator_def =
+            ValidatorDefinition::new_keystore_with_password(&dest_keystore, password_opt)
+                .map_err(|e| format!("Unable to create new validator definition: {:?}", e))?;
+
+        defs.push(validator_def);
+
+        defs.save(&validator_dir)
+            .map_err(|e| format!("Unable to save {}: {:?}", CONFIG_FILENAME, e))?;
+
+        eprintln!("Successfully updated {}.", CONFIG_FILENAME);
+    }
+
+    eprintln!("");
+    eprintln!(
+        "Successfully imported {} validators ({} skipped).",
+        num_imported_keystores,
+        keystore_paths.len() - num_imported_keystores
+    );
+    eprintln!("");
+    eprintln!("WARNING: {}", KEYSTORE_REUSE_WARNING);
+
+    Ok(())
+}