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//! Service discovery client key providers.
use crate::config::restricted_discovery::HsClientNickname;
use crate::internal_prelude::*;
use derive_more::From;
use std::collections::BTreeMap;
use std::fs::DirEntry;
use derive_more::{AsRef, Into};
use fs_mistrust::{CheckedDir, Mistrust, MistrustBuilder};
use amplify::Getters;
use serde_with::DisplayFromStr;
use tor_config::define_list_builder_helper;
use tor_config::derive::prelude::*;
use tor_config::extend_builder::extend_with_replace;
use tor_config::mistrust::BuilderExt as _;
use tor_config_path::{CfgPath, CfgPathError, CfgPathResolver};
use tor_error::warn_report;
use tor_hscrypto::pk::HsClientDescEncKeyParseError;
use tor_persist::slug::BadSlug;
/// A static mapping from [`HsClientNickname`] to client discovery keys.
#[serde_with::serde_as]
#[derive(Default, Debug, Clone, Eq, PartialEq)] //
#[derive(Into, From, AsRef, Serialize, Deserialize)]
pub struct StaticKeyProvider(
#[serde_as(as = "BTreeMap<DisplayFromStr, DisplayFromStr>")]
BTreeMap<HsClientNickname, HsClientDescEncKey>,
);
define_list_builder_helper! {
#[derive(Eq, PartialEq)]
pub struct StaticKeyProviderBuilder {
keys : [(HsClientNickname, HsClientDescEncKey)],
}
built: StaticKeyProvider = build_static(keys)?;
default = vec![];
item_build: |value| Ok(value.clone());
item_apply_defaults: |_| Ok::<_, tor_config::ConfigBuildError>(());
#[serde(try_from = "StaticKeyProvider", into = "StaticKeyProvider")]
impl TryFrom<StaticKeyProvider> for StaticKeyProviderBuilder {
type Error = ConfigBuildError;
fn try_from(value: StaticKeyProvider) -> Result<Self, Self::Error> {
let mut list_builder = StaticKeyProviderBuilder::default();
for (nickname, key) in value.0 {
list_builder.access().push((nickname, key));
Ok(list_builder)
impl From<StaticKeyProviderBuilder> for StaticKeyProvider {
/// Convert our Builder representation of a set of static keys into the
/// format that serde will serialize.
///
/// Note: This is a potentially lossy conversion, since the serialized format
/// can't represent a collection of keys with duplicate nicknames.
fn from(value: StaticKeyProviderBuilder) -> Self {
let mut map = BTreeMap::new();
for (nickname, key) in value.keys.into_iter().flatten() {
map.insert(nickname, key);
Self(map)
/// Helper for building a [`StaticKeyProvider`] out of a list of client keys.
/// Returns an error if the list contains duplicate keys
fn build_static(
keys: Vec<(HsClientNickname, HsClientDescEncKey)>,
) -> Result<StaticKeyProvider, ConfigBuildError> {
let mut key_map = BTreeMap::new();
for (nickname, key) in keys.into_iter() {
if key_map.insert(nickname.clone(), key).is_some() {
return Err(ConfigBuildError::Invalid {
field: "keys".into(),
problem: format!("Multiple client keys for nickname {nickname}"),
});
};
Ok(StaticKeyProvider(key_map))
/// A directory containing the client keys, each in the
/// `descriptor:x25519:<base32-encoded-x25519-public-key>` format.
/// Each file in this directory must have a file name of the form `<nickname>.auth`,
/// where `<nickname>` is a valid [`HsClientNickname`].
#[derive(Debug, Clone, Deftly, Eq, PartialEq, Getters)]
#[derive_deftly(TorConfig)]
#[deftly(tor_config(no_default_trait))]
pub struct DirectoryKeyProvider {
/// The path.
#[deftly(tor_config(no_default))]
path: CfgPath,
/// Configuration about which permissions we want to enforce on our files.
#[deftly(tor_config(
sub_builder(build_fn = "build_for_arti"),
extend_with = "extend_with_replace"
))]
permissions: Mistrust,
/// The serialized format of a [`DirectoryKeyProviderListBuilder`]:
pub type DirectoryKeyProviderList = Vec<DirectoryKeyProvider>;
pub struct DirectoryKeyProviderListBuilder {
key_dirs: [DirectoryKeyProviderBuilder],
built: DirectoryKeyProviderList = key_dirs;
impl DirectoryKeyProvider {
/// Read the client service discovery keys from the specified directory.
pub(super) fn read_keys(
&self,
path_resolver: &CfgPathResolver,
) -> Result<Vec<(HsClientNickname, HsClientDescEncKey)>, DirectoryKeyProviderError> {
let dir_path = self.path.path(path_resolver).map_err(|err| {
DirectoryKeyProviderError::PathExpansionFailed {
path: self.path.clone(),
err,
})?;
let checked_dir = self
.permissions
.verifier()
.secure_dir(&dir_path)
.map_err(|err| DirectoryKeyProviderError::FsMistrust {
path: dir_path.clone(),
// TODO: should this be a method on CheckedDir?
Ok(fs::read_dir(checked_dir.as_path())
.map_err(|e| DirectoryKeyProviderError::IoError(Arc::new(e)))?
.flat_map(|entry| match read_key_file(&checked_dir, entry) {
Ok((client_nickname, key)) => Some((client_nickname, key)),
Err(e) => {
warn_report!(e, "Failed to read client discovery key",);
None
})
.collect_vec())
/// Read the client key at `path`.
fn read_key_file(
checked_dir: &CheckedDir,
entry: io::Result<DirEntry>,
) -> Result<(HsClientNickname, HsClientDescEncKey), DirectoryKeyProviderError> {
/// The extension the client key files are expected to have.
const KEY_EXTENSION: &str = "auth";
let entry = entry.map_err(|e| DirectoryKeyProviderError::IoError(Arc::new(e)))?;
if entry.path().is_dir() {
return Err(DirectoryKeyProviderError::InvalidKeyDirectoryEntry {
path: entry.path(),
problem: "entry is a directory".into(),
let file_name = entry.file_name();
let file_name: &Path = file_name.as_ref();
let extension = file_name.extension().and_then(|e| e.to_str());
if extension != Some(KEY_EXTENSION) {
path: file_name.into(),
problem: "invalid extension (file must end in .auth)".into(),
// We unwrap_or_default() instead of returning an error if the file stem is None,
// because empty slugs handled by HsClientNickname::from_str (they are rejected).
let client_nickname = file_name
.file_stem()
.and_then(|e| e.to_str())
.unwrap_or_default();
let client_nickname = HsClientNickname::from_str(client_nickname)?;
let key = checked_dir.read_to_string(file_name).map_err(|err| {
DirectoryKeyProviderError::FsMistrust {
let parsed_key = HsClientDescEncKey::from_str(key.trim()).map_err(|err| {
DirectoryKeyProviderError::KeyParse {
Ok((client_nickname, parsed_key))
/// Error type representing an invalid [`DirectoryKeyProvider`].
#[derive(Debug, Clone, thiserror::Error)]
pub(super) enum DirectoryKeyProviderError {
/// Encountered an inaccessible path or invalid permissions.
#[error("Inaccessible path or bad permissions on {path}")]
FsMistrust {
/// The path of the key we were trying to read.
path: PathBuf,
/// The underlying error.
#[source]
err: fs_mistrust::Error,
},
/// Encountered an error while reading the keys from disk.
#[error("IO error while reading discovery keys")]
IoError(#[source] Arc<io::Error>),
/// We couldn't expand a path.
#[error("Failed to expand path {path}")]
PathExpansionFailed {
/// The offending path.
/// The error encountered.
err: CfgPathError,
/// Found an invalid key entry.
#[error("{path} is not a valid key entry: {problem}")]
InvalidKeyDirectoryEntry {
/// The problem we encountered.
problem: String,
/// Failed to parse a client nickname.
#[error("Invalid client nickname")]
ClientNicknameParse(#[from] BadSlug),
/// Failed to parse a key.
#[error("Failed to parse key at {path}")]
KeyParse {
/// The path of the key we were trying to parse.
err: HsClientDescEncKeyParseError,