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use std::io;
use std::path::PathBuf;
use std::sync::Arc;
use async_trait::async_trait;
use distant_net::common::ConnectionId;
use distant_net::server::{Reply, RequestCtx, ServerHandler};
use log::*;
use crate::protocol::{
self, ChangeKind, DirEntry, Environment, Error, Metadata, Permissions, ProcessId, PtySize,
SearchId, SearchQuery, SetPermissionsOptions, SystemInfo, Version,
};
mod reply;
use reply::DistantSingleReply;
/// Represents the context provided to the [`DistantApi`] for incoming requests
pub struct DistantCtx {
pub connection_id: ConnectionId,
pub reply: Box<dyn Reply<Data = protocol::Response>>,
}
/// Represents a [`ServerHandler`] that leverages an API compliant with `distant`
pub struct DistantApiServerHandler<T>
where
T: DistantApi,
{
api: Arc<T>,
}
impl<T> DistantApiServerHandler<T>
where
T: DistantApi,
{
pub fn new(api: T) -> Self {
Self { api: Arc::new(api) }
}
}
#[inline]
fn unsupported<T>(label: &str) -> io::Result<T> {
Err(io::Error::new(
io::ErrorKind::Unsupported,
format!("{label} is unsupported"),
))
}
/// Interface to support the suite of functionality available with distant,
/// which can be used to build other servers that are compatible with distant
#[async_trait]
pub trait DistantApi {
/// Invoked whenever a new connection is established.
#[allow(unused_variables)]
async fn on_connect(&self, id: ConnectionId) -> io::Result<()> {
Ok(())
}
/// Invoked whenever an existing connection is dropped.
#[allow(unused_variables)]
async fn on_disconnect(&self, id: ConnectionId) -> io::Result<()> {
Ok(())
}
/// Retrieves information about the server's capabilities.
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn version(&self, ctx: DistantCtx) -> io::Result<Version> {
unsupported("version")
}
/// Reads bytes from a file.
///
/// * `path` - the path to the file
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn read_file(&self, ctx: DistantCtx, path: PathBuf) -> io::Result<Vec<u8>> {
unsupported("read_file")
}
/// Reads bytes from a file as text.
///
/// * `path` - the path to the file
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn read_file_text(&self, ctx: DistantCtx, path: PathBuf) -> io::Result<String> {
unsupported("read_file_text")
}
/// Writes bytes to a file, overwriting the file if it exists.
///
/// * `path` - the path to the file
/// * `data` - the data to write
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn write_file(&self, ctx: DistantCtx, path: PathBuf, data: Vec<u8>) -> io::Result<()> {
unsupported("write_file")
}
/// Writes text to a file, overwriting the file if it exists.
///
/// * `path` - the path to the file
/// * `data` - the data to write
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn write_file_text(
&self,
ctx: DistantCtx,
path: PathBuf,
data: String,
) -> io::Result<()> {
unsupported("write_file_text")
}
/// Writes bytes to the end of a file, creating it if it is missing.
///
/// * `path` - the path to the file
/// * `data` - the data to append
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn append_file(&self, ctx: DistantCtx, path: PathBuf, data: Vec<u8>) -> io::Result<()> {
unsupported("append_file")
}
/// Writes bytes to the end of a file, creating it if it is missing.
///
/// * `path` - the path to the file
/// * `data` - the data to append
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn append_file_text(
&self,
ctx: DistantCtx,
path: PathBuf,
data: String,
) -> io::Result<()> {
unsupported("append_file_text")
}
/// Reads entries from a directory.
///
/// * `path` - the path to the directory
/// * `depth` - how far to traverse the directory, 0 being unlimited
/// * `absolute` - if true, will return absolute paths instead of relative paths
/// * `canonicalize` - if true, will canonicalize entry paths before returned
/// * `include_root` - if true, will include the directory specified in the entries
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn read_dir(
&self,
ctx: DistantCtx,
path: PathBuf,
depth: usize,
absolute: bool,
canonicalize: bool,
include_root: bool,
) -> io::Result<(Vec<DirEntry>, Vec<io::Error>)> {
unsupported("read_dir")
}
/// Creates a directory.
///
/// * `path` - the path to the directory
/// * `all` - if true, will create all missing parent components
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn create_dir(&self, ctx: DistantCtx, path: PathBuf, all: bool) -> io::Result<()> {
unsupported("create_dir")
}
/// Copies some file or directory.
///
/// * `src` - the path to the file or directory to copy
/// * `dst` - the path where the copy will be placed
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn copy(&self, ctx: DistantCtx, src: PathBuf, dst: PathBuf) -> io::Result<()> {
unsupported("copy")
}
/// Removes some file or directory.
///
/// * `path` - the path to a file or directory
/// * `force` - if true, will remove non-empty directories
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn remove(&self, ctx: DistantCtx, path: PathBuf, force: bool) -> io::Result<()> {
unsupported("remove")
}
/// Renames some file or directory.
///
/// * `src` - the path to the file or directory to rename
/// * `dst` - the new name for the file or directory
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn rename(&self, ctx: DistantCtx, src: PathBuf, dst: PathBuf) -> io::Result<()> {
unsupported("rename")
}
/// Watches a file or directory for changes.
///
/// * `path` - the path to the file or directory
/// * `recursive` - if true, will watch for changes within subdirectories and beyond
/// * `only` - if non-empty, will limit reported changes to those included in this list
/// * `except` - if non-empty, will limit reported changes to those not included in this list
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn watch(
&self,
ctx: DistantCtx,
path: PathBuf,
recursive: bool,
only: Vec<ChangeKind>,
except: Vec<ChangeKind>,
) -> io::Result<()> {
unsupported("watch")
}
/// Removes a file or directory from being watched.
///
/// * `path` - the path to the file or directory
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn unwatch(&self, ctx: DistantCtx, path: PathBuf) -> io::Result<()> {
unsupported("unwatch")
}
/// Checks if the specified path exists.
///
/// * `path` - the path to the file or directory
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn exists(&self, ctx: DistantCtx, path: PathBuf) -> io::Result<bool> {
unsupported("exists")
}
/// Reads metadata for a file or directory.
///
/// * `path` - the path to the file or directory
/// * `canonicalize` - if true, will include a canonicalized path in the metadata
/// * `resolve_file_type` - if true, will resolve symlinks to underlying type (file or dir)
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn metadata(
&self,
ctx: DistantCtx,
path: PathBuf,
canonicalize: bool,
resolve_file_type: bool,
) -> io::Result<Metadata> {
unsupported("metadata")
}
/// Sets permissions for a file, directory, or symlink.
///
/// * `path` - the path to the file, directory, or symlink
/// * `resolve_symlink` - if true, will resolve the path to the underlying file/directory
/// * `permissions` - the new permissions to apply
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn set_permissions(
&self,
ctx: DistantCtx,
path: PathBuf,
permissions: Permissions,
options: SetPermissionsOptions,
) -> io::Result<()> {
unsupported("set_permissions")
}
/// Searches files for matches based on a query.
///
/// * `query` - the specific query to perform
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn search(&self, ctx: DistantCtx, query: SearchQuery) -> io::Result<SearchId> {
unsupported("search")
}
/// Cancels an actively-ongoing search.
///
/// * `id` - the id of the search to cancel
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn cancel_search(&self, ctx: DistantCtx, id: SearchId) -> io::Result<()> {
unsupported("cancel_search")
}
/// Spawns a new process, returning its id.
///
/// * `cmd` - the full command to run as a new process (including arguments)
/// * `environment` - the environment variables to associate with the process
/// * `current_dir` - the alternative current directory to use with the process
/// * `pty` - if provided, will run the process within a PTY of the given size
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn proc_spawn(
&self,
ctx: DistantCtx,
cmd: String,
environment: Environment,
current_dir: Option<PathBuf>,
pty: Option<PtySize>,
) -> io::Result<ProcessId> {
unsupported("proc_spawn")
}
/// Kills a running process by its id.
///
/// * `id` - the unique id of the process
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn proc_kill(&self, ctx: DistantCtx, id: ProcessId) -> io::Result<()> {
unsupported("proc_kill")
}
/// Sends data to the stdin of the process with the specified id.
///
/// * `id` - the unique id of the process
/// * `data` - the bytes to send to stdin
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn proc_stdin(&self, ctx: DistantCtx, id: ProcessId, data: Vec<u8>) -> io::Result<()> {
unsupported("proc_stdin")
}
/// Resizes the PTY of the process with the specified id.
///
/// * `id` - the unique id of the process
/// * `size` - the new size of the pty
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn proc_resize_pty(
&self,
ctx: DistantCtx,
id: ProcessId,
size: PtySize,
) -> io::Result<()> {
unsupported("proc_resize_pty")
}
/// Retrieves information about the system.
///
/// *Override this, otherwise it will return "unsupported" as an error.*
#[allow(unused_variables)]
async fn system_info(&self, ctx: DistantCtx) -> io::Result<SystemInfo> {
unsupported("system_info")
}
}
#[async_trait]
impl<T> ServerHandler for DistantApiServerHandler<T>
where
T: DistantApi + Send + Sync + 'static,
{
type Request = protocol::Msg<protocol::Request>;
type Response = protocol::Msg<protocol::Response>;
/// Overridden to leverage [`DistantApi`] implementation of `on_connect`.
async fn on_connect(&self, id: ConnectionId) -> io::Result<()> {
T::on_connect(&self.api, id).await
}
/// Overridden to leverage [`DistantApi`] implementation of `on_disconnect`.
async fn on_disconnect(&self, id: ConnectionId) -> io::Result<()> {
T::on_disconnect(&self.api, id).await
}
async fn on_request(&self, ctx: RequestCtx<Self::Request, Self::Response>) {
let RequestCtx {
connection_id,
request,
reply,
} = ctx;
// Convert our reply to a queued reply so we can ensure that the result
// of an API function is sent back before anything else
let reply = reply.queue();
// Process single vs batch requests
let response = match request.payload {
protocol::Msg::Single(data) => {
let ctx = DistantCtx {
connection_id,
reply: Box::new(DistantSingleReply::from(reply.clone_reply())),
};
let data = handle_request(Arc::clone(&self.api), ctx, data).await;
// Report outgoing errors in our debug logs
if let protocol::Response::Error(x) = &data {
debug!("[Conn {}] {}", connection_id, x);
}
protocol::Msg::Single(data)
}
protocol::Msg::Batch(list)
if matches!(request.header.get_as("sequence"), Some(Ok(true))) =>
{
let mut out = Vec::new();
let mut has_failed = false;
for data in list {
// Once we hit a failure, all remaining requests return interrupted
if has_failed {
out.push(protocol::Response::Error(protocol::Error {
kind: protocol::ErrorKind::Interrupted,
description: String::from("Canceled due to earlier error"),
}));
continue;
}
let ctx = DistantCtx {
connection_id,
reply: Box::new(DistantSingleReply::from(reply.clone_reply())),
};
let data = handle_request(Arc::clone(&self.api), ctx, data).await;
// Report outgoing errors in our debug logs and mark as failed
// to cancel any future tasks being run
if let protocol::Response::Error(x) = &data {
debug!("[Conn {}] {}", connection_id, x);
has_failed = true;
}
out.push(data);
}
protocol::Msg::Batch(out)
}
protocol::Msg::Batch(list) => {
let mut tasks = Vec::new();
// If sequence specified as true, we want to process in order, otherwise we can
// process in any order
for data in list {
let api = Arc::clone(&self.api);
let ctx = DistantCtx {
connection_id,
reply: Box::new(DistantSingleReply::from(reply.clone_reply())),
};
let task = tokio::spawn(async move {
let data = handle_request(api, ctx, data).await;
// Report outgoing errors in our debug logs
if let protocol::Response::Error(x) = &data {
debug!("[Conn {}] {}", connection_id, x);
}
data
});
tasks.push(task);
}
let out = futures::future::join_all(tasks)
.await
.into_iter()
.map(|x| match x {
Ok(x) => x,
Err(x) => protocol::Response::Error(x.to_string().into()),
})
.collect();
protocol::Msg::Batch(out)
}
};
// Queue up our result to go before ANY of the other messages that might be sent.
// This is important to avoid situations such as when a process is started, but before
// the confirmation can be sent some stdout or stderr is captured and sent first.
if let Err(x) = reply.send_before(response) {
error!("[Conn {}] Failed to send response: {}", connection_id, x);
}
// Flush out all of our replies thus far and toggle to no longer hold submissions
if let Err(x) = reply.flush(false) {
error!(
"[Conn {}] Failed to flush response queue: {}",
connection_id, x
);
}
}
}
/// Processes an incoming request
async fn handle_request<T>(
api: Arc<T>,
ctx: DistantCtx,
request: protocol::Request,
) -> protocol::Response
where
T: DistantApi + Send + Sync,
{
match request {
protocol::Request::Version {} => api
.version(ctx)
.await
.map(protocol::Response::Version)
.unwrap_or_else(protocol::Response::from),
protocol::Request::FileRead { path } => api
.read_file(ctx, path)
.await
.map(|data| protocol::Response::Blob { data })
.unwrap_or_else(protocol::Response::from),
protocol::Request::FileReadText { path } => api
.read_file_text(ctx, path)
.await
.map(|data| protocol::Response::Text { data })
.unwrap_or_else(protocol::Response::from),
protocol::Request::FileWrite { path, data } => api
.write_file(ctx, path, data)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::FileWriteText { path, text } => api
.write_file_text(ctx, path, text)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::FileAppend { path, data } => api
.append_file(ctx, path, data)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::FileAppendText { path, text } => api
.append_file_text(ctx, path, text)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::DirRead {
path,
depth,
absolute,
canonicalize,
include_root,
} => api
.read_dir(ctx, path, depth, absolute, canonicalize, include_root)
.await
.map(|(entries, errors)| protocol::Response::DirEntries {
entries,
errors: errors.into_iter().map(Error::from).collect(),
})
.unwrap_or_else(protocol::Response::from),
protocol::Request::DirCreate { path, all } => api
.create_dir(ctx, path, all)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::Remove { path, force } => api
.remove(ctx, path, force)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::Copy { src, dst } => api
.copy(ctx, src, dst)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::Rename { src, dst } => api
.rename(ctx, src, dst)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::Watch {
path,
recursive,
only,
except,
} => api
.watch(ctx, path, recursive, only, except)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::Unwatch { path } => api
.unwatch(ctx, path)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::Exists { path } => api
.exists(ctx, path)
.await
.map(|value| protocol::Response::Exists { value })
.unwrap_or_else(protocol::Response::from),
protocol::Request::Metadata {
path,
canonicalize,
resolve_file_type,
} => api
.metadata(ctx, path, canonicalize, resolve_file_type)
.await
.map(protocol::Response::Metadata)
.unwrap_or_else(protocol::Response::from),
protocol::Request::SetPermissions {
path,
permissions,
options,
} => api
.set_permissions(ctx, path, permissions, options)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::Search { query } => api
.search(ctx, query)
.await
.map(|id| protocol::Response::SearchStarted { id })
.unwrap_or_else(protocol::Response::from),
protocol::Request::CancelSearch { id } => api
.cancel_search(ctx, id)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::ProcSpawn {
cmd,
environment,
current_dir,
pty,
} => api
.proc_spawn(ctx, cmd.into(), environment, current_dir, pty)
.await
.map(|id| protocol::Response::ProcSpawned { id })
.unwrap_or_else(protocol::Response::from),
protocol::Request::ProcKill { id } => api
.proc_kill(ctx, id)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::ProcStdin { id, data } => api
.proc_stdin(ctx, id, data)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::ProcResizePty { id, size } => api
.proc_resize_pty(ctx, id, size)
.await
.map(|_| protocol::Response::Ok)
.unwrap_or_else(protocol::Response::from),
protocol::Request::SystemInfo {} => api
.system_info(ctx)
.await
.map(protocol::Response::SystemInfo)
.unwrap_or_else(protocol::Response::from),
}
}