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/*
* Copyright 2024 The Dragonfly Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
use dragonfly_client_core::{
error::{ErrorType, OrErr},
Error, Result,
};
use libloading::Library;
use reqwest::header::HeaderMap;
use rustls_pki_types::CertificateDer;
use std::fs;
use std::path::Path;
use std::{collections::HashMap, pin::Pin, time::Duration};
use tokio::io::{AsyncRead, AsyncReadExt};
use tracing::{error, info, warn};
use url::Url;
pub mod http;
// NAME is the name of the package.
pub const NAME: &str = "backend";
// Body is the body of the response.
pub type Body = Box<dyn AsyncRead + Send + Unpin>;
// HeadRequest is the head request for backend.
pub struct HeadRequest {
// url is the url of the request.
pub url: String,
// http_header is the headers of the request.
pub http_header: Option<HeaderMap>,
// timeout is the timeout of the request.
pub timeout: Duration,
// client_certs is the client certificates for the request.
pub client_certs: Option<Vec<CertificateDer<'static>>>,
}
// HeadResponse is the head response for backend.
pub struct HeadResponse {
// http_header is the headers of the response.
pub http_header: Option<HeaderMap>,
// http_status_code is the status code of the response.
pub http_status_code: Option<reqwest::StatusCode>,
}
// GetRequest is the get request for backend.
pub struct GetRequest {
// url is the url of the request.
pub url: String,
// http_header is the headers of the request.
pub http_header: Option<HeaderMap>,
// timeout is the timeout of the request.
pub timeout: Duration,
// client_certs is the client certificates for the request.
pub client_certs: Option<Vec<CertificateDer<'static>>>,
}
// GetResponse is the get response for backend.
pub struct GetResponse<R>
where
R: AsyncRead + Unpin,
{
// http_header is the headers of the response.
pub http_header: Option<HeaderMap>,
// http_status_code is the status code of the response.
pub http_status_code: Option<reqwest::StatusCode>,
// body is the content of the response.
pub reader: R,
}
// GetResponse implements the response functions.
impl<R> GetResponse<R>
where
R: AsyncRead + Unpin,
{
pub async fn text(&mut self) -> Result<String> {
let mut buffer = String::new();
Pin::new(&mut self.reader)
.read_to_string(&mut buffer)
.await?;
Ok(buffer)
}
}
// Backend is the interface of the backend.
#[tonic::async_trait]
pub trait Backend {
// head gets the header of the request.
async fn head(&self, request: HeadRequest) -> Result<HeadResponse>;
// get gets the content of the request.
async fn get(&self, request: GetRequest) -> Result<GetResponse<Body>>;
}
// BackendFactory is the factory of the backend.
#[derive(Default)]
pub struct BackendFactory {
// backends is the backends of the factory, including the plugin backends and
// the builtin backends.
backends: HashMap<String, Box<dyn Backend + Send + Sync>>,
}
// BackendFactory implements the factory of the backend. It supports loading builtin
// backends and plugin backends.
//
// The builtin backends are http, https, etc, which are implemented
// by the HTTP struct.
//
// The plugin backends are shared libraries, which are loaded
// by the `register_plugin` function. The file name of the shared
// library is the scheme of the backend. The shared library
// should implement the Backend trait. Default plugin directory
// is `/var/lib/dragonfly/plugins/` in linux and `~/.dragonfly/plugins`
// in macos. The plugin directory can be set by the dfdaemon configuration.
//
// For example:
// If implement a plugin backend named `hdfs`, the shared library
// should be named `libhdfs.so` or `libhdfs.dylib` and move the file to the backend plugin directory
// `/var/lib/dragonfly/plugins/backend/` in linux or `~/.dragonfly/plugins/backend/`
// in macos. When the dfdaemon starts, it will load the `hdfs` plugin backend in the
// backend plugin directory. So the dfdaemon or dfget can use the `hdfs` plugin backend
// to download the file by the url `hdfs://example.com/file`.
// The backend plugin implementation can refer to
// https://github.com/dragonflyoss/client/tree/main/dragonfly-client-backend/examples/plugin/.
impl BackendFactory {
// new returns a new BackendFactory.
pub fn new(plugin_dir: Option<&Path>) -> Result<Self> {
let mut backend_factory = Self::default();
backend_factory.load_builtin_backends();
if let Some(plugin_dir) = plugin_dir {
backend_factory
.load_plugin_backends(plugin_dir)
.map_err(|err| {
error!("failed to load plugin backends: {}", err);
err
})?;
}
Ok(backend_factory)
}
// build returns the backend by the scheme of the url.
pub fn build(&self, url: &str) -> Result<&(dyn Backend + Send + Sync)> {
let url = Url::parse(url).or_err(ErrorType::ParseError)?;
let scheme = url.scheme();
self.backends
.get(scheme)
.map(|boxed_backend| &**boxed_backend)
.ok_or(Error::InvalidParameter)
}
// load_builtin_backends loads the builtin backends.
fn load_builtin_backends(&mut self) {
self.backends
.insert("http".to_string(), Box::new(http::HTTP::new()));
info!("load [http] builtin backend");
self.backends
.insert("https".to_string(), Box::new(http::HTTP::new()));
info!("load [https] builtin backend ");
}
// load_plugin_backends loads the plugin backends.
fn load_plugin_backends(&mut self, plugin_dir: &Path) -> Result<()> {
let backend_plugin_dir = plugin_dir.join(NAME);
if !backend_plugin_dir.exists() {
warn!(
"skip loading plugin backends, because the plugin directory {} does not exist",
plugin_dir.display()
);
return Ok(());
}
for entry in fs::read_dir(backend_plugin_dir)? {
let path = entry?.path();
// Load shared libraries by register_plugin function,
// file name is the scheme of the backend.
unsafe {
let lib = Library::new(path.as_os_str()).or_err(ErrorType::PluginError)?;
let register_plugin: libloading::Symbol<
unsafe extern "C" fn() -> Box<dyn Backend + Send + Sync>,
> = lib.get(b"register_plugin").or_err(ErrorType::PluginError)?;
if let Some(file_stem) = path.file_stem() {
if let Some(plugin_name) =
file_stem.to_string_lossy().to_string().strip_prefix("lib")
{
self.backends
.insert(plugin_name.to_string(), register_plugin());
info!("load [{}] plugin backend", plugin_name);
}
}
}
}
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn should_return_http_backend() {
let backend_factory =
BackendFactory::new(Some(Path::new("/var/lib/dragonfly/plugins/backend/"))).unwrap();
let backend = backend_factory.build("http://example.com");
assert!(backend.is_ok());
}
}