use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
pub const SERVICE_NAME: &str = "com.apple.mobile.file_relay";
#[derive(Debug, thiserror::Error)]
pub enum FileRelayError {
#[error("IO error: {0}")]
Io(#[from] std::io::Error),
#[error("plist error: {0}")]
Plist(String),
#[error("protocol error: {0}")]
Protocol(String),
}
pub struct FileRelayClient<S> {
stream: S,
}
impl<S: AsyncRead + AsyncWrite + Unpin> FileRelayClient<S> {
pub fn new(stream: S) -> Self {
Self { stream }
}
pub async fn request_sources(&mut self, sources: &[&str]) -> Result<Vec<u8>, FileRelayError> {
let request = plist::Dictionary::from_iter([(
"Sources".to_string(),
plist::Value::Array(
sources
.iter()
.map(|source| plist::Value::String((*source).to_string()))
.collect(),
),
)]);
send_plist(&mut self.stream, &plist::Value::Dictionary(request)).await?;
let response = recv_plist(&mut self.stream).await?;
match response.get("Status").and_then(plist::Value::as_string) {
Some("Acknowledged") => {}
Some(other) => {
let error = response
.get("Error")
.and_then(plist::Value::as_string)
.unwrap_or(other);
return Err(FileRelayError::Protocol(error.to_string()));
}
None => {
return Err(FileRelayError::Protocol(
"file relay response missing Status".into(),
));
}
}
let mut data = Vec::new();
self.stream.read_to_end(&mut data).await?;
Ok(data)
}
}
async fn send_plist<S: AsyncWrite + Unpin>(
stream: &mut S,
value: &plist::Value,
) -> Result<(), FileRelayError> {
let mut buf = Vec::new();
plist::to_writer_xml(&mut buf, value).map_err(|e| FileRelayError::Plist(e.to_string()))?;
stream.write_all(&(buf.len() as u32).to_be_bytes()).await?;
stream.write_all(&buf).await?;
stream.flush().await?;
Ok(())
}
async fn recv_plist<S: AsyncRead + Unpin>(
stream: &mut S,
) -> Result<plist::Dictionary, FileRelayError> {
let mut len_buf = [0u8; 4];
stream.read_exact(&mut len_buf).await?;
let len = u32::from_be_bytes(len_buf) as usize;
const MAX_PLIST_SIZE: usize = 1024 * 1024;
if len > MAX_PLIST_SIZE {
return Err(FileRelayError::Protocol(format!(
"plist length {len} exceeds max {MAX_PLIST_SIZE}"
)));
}
let mut buf = vec![0u8; len];
stream.read_exact(&mut buf).await?;
plist::from_bytes(&buf).map_err(|e| FileRelayError::Plist(e.to_string()))
}
#[cfg(test)]
mod tests {
use std::pin::Pin;
use std::task::{Context, Poll};
use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
use super::*;
struct MockStream {
read_buf: Vec<u8>,
written: Vec<u8>,
read_pos: usize,
}
impl MockStream {
fn with_response(plist_value: plist::Value, raw: &[u8]) -> Self {
let mut payload = Vec::new();
plist::to_writer_xml(&mut payload, &plist_value).unwrap();
let mut read_buf = Vec::new();
read_buf.extend_from_slice(&(payload.len() as u32).to_be_bytes());
read_buf.extend_from_slice(&payload);
read_buf.extend_from_slice(raw);
Self {
read_buf,
written: Vec::new(),
read_pos: 0,
}
}
}
impl AsyncRead for MockStream {
fn poll_read(
mut self: Pin<&mut Self>,
_cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<std::io::Result<()>> {
let remaining = self.read_buf.len().saturating_sub(self.read_pos);
if remaining == 0 {
return Poll::Ready(Ok(()));
}
let to_copy = remaining.min(buf.remaining());
let start = self.read_pos;
let end = start + to_copy;
buf.put_slice(&self.read_buf[start..end]);
self.read_pos = end;
Poll::Ready(Ok(()))
}
}
impl AsyncWrite for MockStream {
fn poll_write(
mut self: Pin<&mut Self>,
_cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<std::io::Result<usize>> {
self.written.extend_from_slice(buf);
Poll::Ready(Ok(buf.len()))
}
fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
Poll::Ready(Ok(()))
}
fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
Poll::Ready(Ok(()))
}
}
#[tokio::test]
async fn request_sources_reads_acknowledged_archive() {
let response = plist::Value::Dictionary(plist::Dictionary::from_iter([(
"Status".to_string(),
plist::Value::String("Acknowledged".into()),
)]));
let mut stream = MockStream::with_response(response, b"archive-bytes");
let mut client = FileRelayClient::new(&mut stream);
let archive = client.request_sources(&["Network"]).await.unwrap();
assert_eq!(archive, b"archive-bytes");
let len = u32::from_be_bytes(stream.written[..4].try_into().unwrap()) as usize;
let payload = &stream.written[4..4 + len];
let dict: plist::Dictionary = plist::from_bytes(payload).unwrap();
let sources = dict["Sources"].as_array().unwrap();
assert_eq!(sources[0].as_string(), Some("Network"));
}
}