Replace manual Debug impls with educe in tor-proto

We now print slighly more information.

Cargo.lock

@@ -3447,6 +3447,7 @@ dependencies = [
  "cipher",
  "coarsetime",
  "digest 0.10.3",
+ "educe",
  "futures",
  "generic-array",
  "hex",

crates/tor-proto/Cargo.toml

@@ -31,6 +31,7 @@ bytes = "1"
 cipher = "0.3.0"
 coarsetime = "0.1.20"
 digest = "0.10.0"
+educe = "0.4.6"
 futures = "0.3.14"
 asynchronous-codec = "0.6.0"
 generic-array = "0.14.3"

crates/tor-proto/src/stream/data.rs

@@ -15,12 +15,15 @@ use tokio_crate::io::{AsyncRead as TokioAsyncRead, AsyncWrite as TokioAsyncWrite
 #[cfg(feature = "tokio")]
 use tokio_util::compat::{FuturesAsyncReadCompatExt, FuturesAsyncWriteCompatExt};
 
-use std::fmt::{self, Debug};
+use std::fmt::Debug;
 use std::io::Result as IoResult;
 use std::pin::Pin;
 
+use educe::Educe;
+
 use crate::circuit::StreamTarget;
 use crate::stream::StreamReader;
+use tor_bytes::skip_fmt;
 use tor_cell::relaycell::msg::{Data, RelayMsg};
 use tor_error::internal;
 
@@ -258,6 +261,8 @@ impl TokioAsyncWrite for DataStream {
 /// We have to use an enum here because, for as long as we're waiting
 /// for a flush operation to complete, the future returned by
 /// `flush_cell()` owns the DataWriterImpl.
+#[derive(Educe)]
+#[educe(Debug)]
 enum DataWriterState {
     /// The writer has closed or gotten an error: nothing more to do.
     Closed,
@@ -265,20 +270,15 @@ enum DataWriterState {
     /// immediately.
     Ready(DataWriterImpl),
     /// The writer is flushing a cell.
-    Flushing(Pin<Box<dyn Future<Output = (DataWriterImpl, Result<()>)> + Send>>),
-}
-
-impl Debug for DataWriterState {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            DataWriterState::Closed => write!(f, "DataWriterState::Closed"),
-            DataWriterState::Ready(i) => write!(f, "DataWriterState::Ready({:?})", i),
-            DataWriterState::Flushing(_) => write!(f, "DataWriterState::Flushing(..)"),
-        }
-    }
+    Flushing(
+        #[educe(Debug(method = "skip_fmt"))]
+        Pin<Box<dyn Future<Output = (DataWriterImpl, Result<()>)> + Send>>,
+    ),
 }
 
 /// Internal: the write part of a DataStream
+#[derive(Educe)]
+#[educe(Debug)]
 struct DataWriterImpl {
     /// The underlying StreamTarget object.
     s: StreamTarget,
@@ -288,21 +288,13 @@ struct DataWriterImpl {
     // enough for now.  If we _do_ make it bigger, we'll have to change
     // our use of Data::split_from to handle the case where we can't fit
     // all the data.
+    #[educe(Debug(method = "skip_fmt"))]
     buf: Box<[u8; Data::MAXLEN]>,
 
     /// Number of unflushed bytes in buf.
     n_pending: usize,
 }
 
-impl Debug for DataWriterImpl {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("DataWriterImpl")
-            .field("s", &self.s)
-            .field("n_pending", &self.n_pending)
-            .finish_non_exhaustive()
-    }
-}
-
 impl DataWriter {
     /// Helper for poll_flush() and poll_close(): Performs a flush, then
     /// closes the stream if should_close is true.
@@ -465,6 +457,8 @@ impl DataWriterImpl {
 /// DataCellImpl.  If we wanted to store the future and the cell at the
 /// same time, we'd need to make a self-referential structure, which isn't
 /// possible in safe Rust AIUI.
+#[derive(Educe)]
+#[educe(Debug)]
 enum DataReaderState {
     /// In this state we have received an end cell or an error.
     Closed,
@@ -473,28 +467,25 @@ enum DataReaderState {
     Ready(DataReaderImpl),
     /// The reader is currently fetching a cell: this future is the
     /// progress it is making.
-    ReadingCell(Pin<Box<dyn Future<Output = (DataReaderImpl, Result<()>)> + Send>>),
-}
-
-impl std::fmt::Debug for DataReaderState {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Self::Closed => write!(f, "Closed"),
-            Self::Ready(_) => write!(f, "Ready"),
-            Self::ReadingCell(_) => write!(f, "ReadingCell"),
-        }
-    }
+    ReadingCell(
+        #[educe(Debug(method = "skip_fmt"))]
+        Pin<Box<dyn Future<Output = (DataReaderImpl, Result<()>)> + Send>>,
+    ),
 }
 
 /// Wrapper for the read part of a DataStream
+#[derive(Educe)]
+#[educe(Debug)]
 struct DataReaderImpl {
     /// The underlying StreamReader object.
+    #[educe(Debug(method = "skip_fmt"))]
     s: StreamReader,
 
     /// If present, data that we received on this stream but have not
     /// been able to send to the caller yet.
     // TODO: This data structure is probably not what we want, but
     // it's good enough for now.
+    #[educe(Debug(method = "skip_fmt"))]
     pending: Vec<u8>,
 
     /// Index into pending to show what we've already read.