From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 28 Mar 2021 18:43:29 +0000 (+0100)
Subject: packetframe: Initial wip, buggy and not used, but but compiles
X-Git-Tag: otter-0.6.0~586
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=0a06822be8087e920820e6d59cb2e0cb80ede9f5;p=otter.git

packetframe: Initial wip, buggy and not used, but but compiles

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/src/lib.rs b/src/lib.rs
index c9f5ecad..f4cd9207 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -25,6 +25,7 @@ pub mod mgmtchannel;
 pub mod nwtemplates;
 pub mod occultilks;
 pub mod organise;
+pub mod packetframe;
 pub mod pcaliases;
 pub mod pcrender;
 pub mod pieces;
diff --git a/src/packetframe.rs b/src/packetframe.rs
new file mode 100644
index 00000000..5403c24e
--- /dev/null
+++ b/src/packetframe.rs
@@ -0,0 +1,130 @@
+// Copyright 2020-2021 Ian Jackson and contributors to Otter
+// SPDX-License-Identifier: AGPL-3.0-or-later
+// There is NO WARRANTY.
+
+//! Frame format:
+//!    zero or more chunks
+//!    end marker
+//!
+//! Chunk format:
+//!    u16     chunk length, nonzero
+//!    <n>     chunk data
+//! Packet end marker:
+//!    0u16         marker
+//!    0xffffu16    marker, error!
+
+use crate::prelude::*;
+
+const CHUNK_MAX: u16 = 65534;
+const CHUNK_ERR: u16 = 65535;
+
+type BO = BigEndian;
+
+#[derive(Debug)]
+struct Fuse<RW>(Result<RW, Broken>);
+
+#[derive(Debug)]
+pub struct FrameReader<R: BufRead> {
+  inner: Fuse<R>,
+  in_frame: Option<usize>,
+}
+
+#[derive(Debug)]
+pub struct ReadFrame<'r,R:BufRead> {
+  fr: Result<&'r mut FrameReader<R>, Option<SenderError>>,
+}
+
+#[derive(Debug,Copy,Clone,Error)]
+#[error("error occurred at peer, during construction of frame data")]
+struct SenderError;
+
+#[derive(Clone,Error,Debug)]
+pub struct Broken {
+  msg: String,
+  kind: io::ErrorKind,
+}
+
+impl<R:Read> Read for Fuse<R> {
+  #[throws(io::Error)]
+  fn read(&mut self, buf: &mut [u8]) -> usize {
+    match &mut self.0 {
+      Err(broken) => throw!(broken.clone()),
+      Ok(inner) => {
+        let r = inner.read(buf);
+        if let Err(e) = &r {
+          self.0 = Err(Broken {
+            msg: e.to_string(),
+            kind: e.kind(),
+          });
+        }
+        r?
+      }
+    }
+  }
+}
+
+impl From<Broken> for io::Error {
+  fn from(broken: Broken) -> io::Error {
+    io::Error::new(broken.kind, broken)
+  }
+}
+impl From<SenderError> for io::Error {
+  fn from(se: SenderError) -> io::Error {
+    io::Error::new(io::ErrorKind::Other, se)
+  }
+}
+
+impl Display for Broken {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    f.write_str(&self.msg)
+  }
+}
+
+impl<R:BufRead> FrameReader<R> {
+  fn frame<'r>(&'r mut self) -> ReadFrame<'r,R> { ReadFrame {
+    fr: Ok(self),
+  } }
+
+  #[throws(MgmtChannelReadError)]
+  pub fn read_rmp<T:DeserializeOwned>(&mut self) -> T {
+    let mut frame = self.frame();
+    rmp_serde::decode::from_read(&mut frame)
+      .map_err(|e| MgmtChannelReadError::Parse(format!("{}", &e)))?
+  }
+}
+
+impl<'r, R:BufRead> Read for ReadFrame<'r, R> {
+  #[throws(io::Error)]
+  fn read(&mut self, buf: &mut [u8]) -> usize {
+    if buf.len() == 0 { return 0 }
+    loop { match self.fr {
+      Err(None) => return 0,
+      Err(Some(e)) => throw!(e),
+      Ok(ref mut fr) => {
+        if fr.in_frame.is_none() || fr.in_frame == Some(0) {
+          match match fr.inner.read_u16::<BO>()? {
+            0         => Err(None),
+            CHUNK_ERR => Err(Some(SenderError)),
+            x         => Ok(x as usize),
+          } {
+            Err(done) => {
+              fr.in_frame = None;
+              self.fr = Err(done);
+              continue;
+            },
+            Ok(in_chunk) => {
+              fr.in_frame = Some(in_chunk);
+            }
+          };
+        }
+        let remaining = fr.in_frame.as_mut().unwrap();
+
+        let n = min(buf.len(), *remaining);
+        let r = fr.inner.read(&mut buf[0..n])?;
+        assert!(r <= n);
+        *remaining -= n;
+        break r;
+      }
+    } }
+  }
+}
diff --git a/src/prelude.rs b/src/prelude.rs
index 829aad36..cdde169d 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -53,6 +53,7 @@ pub use std::time::{self, Duration, Instant};
 pub use anyhow::{anyhow, ensure, Context};
 pub use arrayvec::ArrayVec;
 pub use boolinator::Boolinator as _;
+pub use byteorder::{BigEndian, LittleEndian, ReadBytesExt, WriteBytesExt};
 pub use cast_trait_object::{dyn_upcast, DynCastExt};
 pub use delegate::delegate;
 pub use derive_more::*;