openethereum/hash-fetch/src/client.rs

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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! Hash-addressed content resolver & fetcher.
use std::{io, fs};
use std::io::Write;
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use std::sync::Arc;
use std::path::PathBuf;
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use hash::keccak_buffer;
use fetch::{Fetch, Response, Error as FetchError, Client as FetchClient};
use futures::{Future, IntoFuture};
use parity_reactor::Remote;
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use urlhint::{ContractClient, URLHintContract, URLHint, URLHintResult};
use ethereum_types::H256;
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/// API for fetching by hash.
pub trait HashFetch: Send + Sync + 'static {
/// Fetch hash-addressed content.
/// Parameters:
/// 1. `hash` - content hash
/// 2. `on_done` - callback function invoked when the content is ready (or there was error during fetch)
///
/// This function may fail immediately when fetch cannot be initialized or content cannot be resolved.
fn fetch(&self, hash: H256, on_done: Box<Fn(Result<PathBuf, Error>) + Send>);
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}
/// Hash-fetching error.
#[derive(Debug)]
pub enum Error {
/// Hash could not be resolved to a valid content address.
NoResolution,
/// Downloaded content hash does not match.
HashMismatch {
/// Expected hash
expected: H256,
/// Computed hash
got: H256,
},
/// Server didn't respond with OK status.
InvalidStatus,
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/// IO Error while validating hash.
IO(io::Error),
/// Error during fetch.
Fetch(FetchError),
}
#[cfg(test)]
impl PartialEq for Error {
fn eq(&self, other: &Self) -> bool {
use Error::*;
match (self, other) {
(&HashMismatch { expected, got }, &HashMismatch { expected: e, got: g }) => {
expected == e && got == g
},
(&NoResolution, &NoResolution) => true,
(&InvalidStatus, &InvalidStatus) => true,
(&IO(_), &IO(_)) => true,
(&Fetch(_), &Fetch(_)) => true,
_ => false,
}
}
}
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impl From<FetchError> for Error {
fn from(error: FetchError) -> Self {
Error::Fetch(error)
}
}
impl From<io::Error> for Error {
fn from(error: io::Error) -> Self {
Error::IO(error)
}
}
fn validate_hash(path: PathBuf, hash: H256, result: Result<Response, FetchError>) -> Result<PathBuf, Error> {
let response = result?;
if !response.is_success() {
return Err(Error::InvalidStatus);
}
// Read the response
let mut reader = io::BufReader::new(response);
let mut writer = io::BufWriter::new(fs::File::create(&path)?);
io::copy(&mut reader, &mut writer)?;
writer.flush()?;
// And validate the hash
let mut file_reader = io::BufReader::new(fs::File::open(&path)?);
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let content_hash = keccak_buffer(&mut file_reader)?;
if content_hash != hash {
Err(Error::HashMismatch{ got: content_hash, expected: hash })
} else {
Ok(path)
}
}
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/// Default Hash-fetching client using on-chain contract to resolve hashes to URLs.
pub struct Client<F: Fetch + 'static = FetchClient> {
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contract: URLHintContract,
fetch: F,
remote: Remote,
random_path: Arc<Fn() -> PathBuf + Sync + Send>,
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}
impl Client {
/// Creates new instance of the `Client` given on-chain contract client and task runner.
pub fn new(contract: Arc<ContractClient>, remote: Remote) -> Self {
Client::with_fetch(contract, FetchClient::new().unwrap(), remote)
}
}
impl<F: Fetch + 'static> Client<F> {
/// Creates new instance of the `Client` given on-chain contract client, fetch service and task runner.
pub fn with_fetch(contract: Arc<ContractClient>, fetch: F, remote: Remote) -> Self {
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Client {
contract: URLHintContract::new(contract),
fetch: fetch,
remote: remote,
random_path: Arc::new(random_temp_path),
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}
}
}
impl<F: Fetch + 'static> HashFetch for Client<F> {
fn fetch(&self, hash: H256, on_done: Box<Fn(Result<PathBuf, Error>) + Send>) {
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debug!(target: "fetch", "Fetching: {:?}", hash);
let random_path = self.random_path.clone();
let remote_fetch = self.fetch.clone();
let future = self.contract.resolve(hash)
.map_err(|e| { warn!("Error resolving URL: {}", e); Error::NoResolution })
.and_then(|maybe_url| maybe_url.ok_or(Error::NoResolution))
.map(|content| match content {
URLHintResult::Dapp(dapp) => {
dapp.url()
},
URLHintResult::GithubDapp(content) => {
content.url
},
URLHintResult::Content(content) => {
content.url
},
})
.into_future()
.and_then(move |url| {
debug!(target: "fetch", "Resolved {:?} to {:?}. Fetching...", hash, url);
let future = remote_fetch.fetch(&url).then(move |result| {
debug!(target: "fetch", "Content fetched, validating hash ({:?})", hash);
let path = random_path();
let res = validate_hash(path.clone(), hash, result);
if let Err(ref err) = res {
trace!(target: "fetch", "Error: {:?}", err);
// Remove temporary file in case of error
let _ = fs::remove_file(&path);
}
res
});
remote_fetch.process(future)
})
.then(move |res| { on_done(res); Ok(()) as Result<(), ()> });
self.remote.spawn(future);
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}
}
fn random_temp_path() -> PathBuf {
use ::rand::Rng;
use ::std::env;
let mut rng = ::rand::OsRng::new().expect("Reliable random source is required to work.");
let file: String = rng.gen_ascii_chars().take(12).collect();
let mut path = env::temp_dir();
path.push(file);
path
}
#[cfg(test)]
mod tests {
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use rustc_hex::FromHex;
use std::sync::{Arc, mpsc};
use parking_lot::Mutex;
use futures::future;
use fetch::{self, Fetch};
use parity_reactor::Remote;
use urlhint::tests::{FakeRegistrar, URLHINT};
use super::{Error, Client, HashFetch, random_temp_path};
#[derive(Clone)]
struct FakeFetch {
return_success: bool
}
impl Fetch for FakeFetch {
type Result = future::Ok<fetch::Response, fetch::Error>;
fn new() -> Result<Self, fetch::Error> where Self: Sized {
Ok(FakeFetch { return_success: true })
}
fn fetch_with_abort(&self, url: &str, _abort: fetch::Abort) -> Self::Result {
assert_eq!(url, "https://parity.io/assets/images/ethcore-black-horizontal.png");
future::ok(if self.return_success {
let cursor = ::std::io::Cursor::new(b"result");
fetch::Response::from_reader(cursor)
} else {
fetch::Response::not_found()
})
}
}
fn registrar() -> FakeRegistrar {
let mut registrar = FakeRegistrar::new();
registrar.responses = Mutex::new(vec![
Ok(format!("000000000000000000000000{}", URLHINT).from_hex().unwrap()),
Ok("00000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000deadcafebeefbeefcafedeaddeedfeedffffffff000000000000000000000000000000000000000000000000000000000000003c68747470733a2f2f7061726974792e696f2f6173736574732f696d616765732f657468636f72652d626c61636b2d686f72697a6f6e74616c2e706e6700000000".from_hex().unwrap()),
]);
registrar
}
#[test]
fn should_return_error_if_hash_not_found() {
// given
let contract = Arc::new(FakeRegistrar::new());
let fetch = FakeFetch { return_success: false };
let client = Client::with_fetch(contract.clone(), fetch, Remote::new_sync());
// when
let (tx, rx) = mpsc::channel();
client.fetch(2.into(), Box::new(move |result| {
tx.send(result).unwrap();
}));
// then
let result = rx.recv().unwrap();
assert_eq!(result.unwrap_err(), Error::NoResolution);
}
#[test]
fn should_return_error_if_response_is_not_successful() {
// given
let registrar = Arc::new(registrar());
let fetch = FakeFetch { return_success: false };
let client = Client::with_fetch(registrar.clone(), fetch, Remote::new_sync());
// when
let (tx, rx) = mpsc::channel();
client.fetch(2.into(), Box::new(move |result| {
tx.send(result).unwrap();
}));
// then
let result = rx.recv().unwrap();
assert_eq!(result.unwrap_err(), Error::InvalidStatus);
}
#[test]
fn should_return_hash_mismatch() {
// given
let registrar = Arc::new(registrar());
let fetch = FakeFetch { return_success: true };
let mut client = Client::with_fetch(registrar.clone(), fetch, Remote::new_sync());
let path = random_temp_path();
let path2 = path.clone();
client.random_path = Arc::new(move || path2.clone());
// when
let (tx, rx) = mpsc::channel();
client.fetch(2.into(), Box::new(move |result| {
tx.send(result).unwrap();
}));
// then
let result = rx.recv().unwrap();
let hash = "0x06b0a4f426f6713234b2d4b2468640bc4e0bb72657a920ad24c5087153c593c8".into();
assert_eq!(result.unwrap_err(), Error::HashMismatch { expected: 2.into(), got: hash });
assert!(!path.exists(), "Temporary file should be removed.");
}
#[test]
fn should_return_path_if_hash_matches() {
// given
let registrar = Arc::new(registrar());
let fetch = FakeFetch { return_success: true };
let client = Client::with_fetch(registrar.clone(), fetch, Remote::new_sync());
// when
let (tx, rx) = mpsc::channel();
client.fetch("0x06b0a4f426f6713234b2d4b2468640bc4e0bb72657a920ad24c5087153c593c8".into(), Box::new(move |result| {
tx.send(result).unwrap();
}));
// then
let result = rx.recv().unwrap();
assert!(result.is_ok(), "Should return path, got: {:?}", result);
}
}