From 0035f38c3c383b72f2ef9d220e3d5478f1b6938b Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Mon, 12 Apr 2021 16:01:09 +0100
Subject: [PATCH] rework stream to (for now) use two different streams with
 distinct types for reading + writing

---
 src/lib.rs    | 11 ++---------
 src/stream.rs | 52 +++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 6cecaf6..950f8f6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,10 +5,6 @@
 #[macro_use] mod ext;
 #[allow(unused_imports)] use ext::*;
 
-use std::sync::Arc;
-use tokio::io::{AsyncWrite, AsyncRead};
-use openssl::symm::Crypter;
-
 // Wrapper for plain/symm-enc stream swapping
 mod dual;
 // Crypto shit
@@ -16,12 +12,9 @@ mod crypt;
 // Stream impls
 mod stream;
 
-
-/// A type that implements both `AsyncWrite` and `AsyncRead`
-pub trait AsyncStream: AsyncRead + AsyncWrite{}
-impl<T: AsyncRead + AsyncWrite + ?Sized> AsyncStream for T{}
-
 pub use stream::{
+    AsyncStream,
+    
     EncryptedStream,
     WriteHalf,
     ReadHalf,
diff --git a/src/stream.rs b/src/stream.rs
index 647414a..9e5d3f4 100644
--- a/src/stream.rs
+++ b/src/stream.rs
@@ -1,9 +1,18 @@
 use super::*;
+
+use tokio::io::{AsyncWrite, AsyncRead};
+use std::sync::Arc;
+use openssl::symm::Crypter;
+
 use crypt::{
     RsaPublicKey,
     RsaPrivateKey,
 };
 
+/// A type that implements both `AsyncWrite` and `AsyncRead`
+pub trait AsyncStream: AsyncRead + AsyncWrite{}
+impl<T: AsyncRead + AsyncWrite + ?Sized> AsyncStream for T{}
+
 /// Inner rsa data for encrypted stream read+write halves
 struct EncryptedStreamMeta
 {
@@ -42,20 +51,55 @@ struct ReadWriteCombined<R, W>
 }
 
 /// RSA/chacha20 encrypted stream
-pub struct EncryptedStream<S>
-where S: AsyncStream
+pub struct EncryptedStream<R, W>
+where R: AsyncRead,
+      W: AsyncWrite,
 {
     meta: EncryptedStreamMeta,
 
     // Keep the streams on the heap to keep this type not hueg.
-    backing: Box<ReadWriteCombined<S, S>>,
+    backing: Box<ReadWriteCombined<R, W>>,
 }
 
-impl<S: AsyncStream> EncryptedStream<S>
+//TODO: How do we use this with a single AsyncStream instead of requiring 2? Will we need to make our own Arc wrapper?? Ugh,, for now let's ignore this I guess... Most read+write thingies have a Read/WriteHalf split mechanism.
+impl<R: AsyncRead, W: AsyncWrite> EncryptedStream<R, W>
 {
     /// Has this stream done its RSA key exchange?
     pub fn has_exchanged(&self) -> bool
     {
 	self.meta.them.is_some()
     }
+
+    /// Split this stream into a read and writeable half. 
+    pub fn split(self) -> (WriteHalf<W>, ReadHalf<R>)
+    {
+	let meta = Arc::new(self.meta);
+	let (read, write) = {
+	    let ReadWriteCombined { cipher_read, backing_read, backing_write }  = *self.backing;
+
+	    ((cipher_read, backing_read), backing_write)
+	};
+
+	(WriteHalf {
+	    meta: Arc::clone(&meta),
+	    backing_write: Box::new(write),
+	}, ReadHalf {
+	    meta,
+	    cipher: read.0,
+	    backing_read: Box::new(read.1),
+	})
+    }
+
+    /// Join a split `EncryptedStream` from halves.
+    ///
+    /// # Panics
+    /// If the read and write half are not from the same split.
+    pub fn from_split((write, read): (WriteHalf<W>, ReadHalf<R>)) -> Self
+    {
+	if !Arc::ptr_eq(&write.meta, &read.meta) {
+	    panic!("Read and Write halves are not from the same split");
+	}
+
+	todo!("Drop write's `meta`, consume read's `meta`. Move the streams into `ReadWriteCombined`")
+    }
 }