From e591af586a6fb33d04fe1064b3362d1784d5c307 Mon Sep 17 00:00:00 2001
From: Maarten de Vries <maarten@de-vri.es>
Date: Mon, 11 Dec 2023 10:08:19 +0100
Subject: [PATCH] Add NativeEndian endianness and use it by default for Unix
 transport.

---
 src/transport/endian.rs      | 60 ++++++++++++++++++++++++++++++++++++
 src/transport/unix/config.rs |  2 +-
 2 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/src/transport/endian.rs b/src/transport/endian.rs
index 2020dc4..b73dea8 100644
--- a/src/transport/endian.rs
+++ b/src/transport/endian.rs
@@ -9,6 +9,13 @@ pub enum Endian {
 
 	/// Encode header fields in big endian.
 	BigEndian,
+
+	/// Encode header fields in the native endianness of the platform.
+	///
+	/// NOTE: You should only use this when you know for sure that the other side of the connection
+	/// is on the same platform, such as when using a Unix socket.
+	/// Otherwise, both sides may select native endianness and end up using a different endianness.
+	NativeEndian,
 }
 
 impl Endian {
@@ -18,6 +25,7 @@ impl Endian {
 		match self {
 			Self::LittleEndian => u32::from_le_bytes(buffer),
 			Self::BigEndian => u32::from_be_bytes(buffer),
+			Self::NativeEndian => u32::from_ne_bytes(buffer),
 		}
 	}
 
@@ -26,6 +34,7 @@ impl Endian {
 		let bytes = match self {
 			Self::LittleEndian => value.to_le_bytes(),
 			Self::BigEndian => value.to_be_bytes(),
+			Self::NativeEndian => value.to_ne_bytes(),
 		};
 		buffer[0..4].copy_from_slice(&bytes);
 	}
@@ -36,6 +45,7 @@ impl Endian {
 		match self {
 			Self::LittleEndian => i32::from_le_bytes(buffer),
 			Self::BigEndian => i32::from_be_bytes(buffer),
+			Self::NativeEndian => i32::from_ne_bytes(buffer),
 		}
 	}
 
@@ -44,6 +54,7 @@ impl Endian {
 		let bytes = match self {
 			Self::LittleEndian => value.to_le_bytes(),
 			Self::BigEndian => value.to_be_bytes(),
+			Self::NativeEndian => value.to_ne_bytes(),
 		};
 		buffer[0..4].copy_from_slice(&bytes);
 	}
@@ -68,6 +79,16 @@ mod test {
 		assert!(buffer == [0x01, 0x02, 0x03, 0x04]);
 	}
 
+	#[test]
+	fn write_u32_native_endian_works() {
+		let mut buffer = [0u8; 4];
+		Endian::LittleEndian.write_u32(&mut buffer, 0x01020304);
+		#[cfg(target_endian = "little")]
+		assert!(buffer == [0x04, 0x03, 0x02, 0x01]);
+		#[cfg(target_endian = "big")]
+		assert!(buffer == [0x01, 0x02, 0x03, 0x04]);
+	}
+
 	#[test]
 	fn read_u32_litte_endian_works() {
 		assert!(Endian::LittleEndian.read_u32(&[0x04, 0x03, 0x02, 0x01]) == 0x01020304);
@@ -78,6 +99,14 @@ mod test {
 		assert!(Endian::BigEndian.read_u32(&[0x01, 0x02, 0x03, 0x04]) == 0x01020304);
 	}
 
+	#[test]
+	fn read_u32_native_endian_works() {
+		#[cfg(target_endian = "little")]
+		assert!(Endian::NativeEndian.read_u32(&[0x04, 0x03, 0x02, 0x01]) == 0x01020304);
+		#[cfg(target_endian = "big")]
+		assert!(Endian::NativeEndian.read_u32(&[0x01, 0x02, 0x03, 0x04]) == 0x01020304);
+	}
+
 	#[test]
 	fn write_i32_litte_endian_works() {
 		let mut buffer = [0u8; 4];
@@ -100,6 +129,23 @@ mod test {
 		assert!(buffer == [0x81, 0x02, 0x03, 0x05]);
 	}
 
+	#[test]
+	fn write_i32_native_endian_works() {
+		let mut buffer = [0u8; 4];
+		Endian::NativeEndian.write_i32(&mut buffer, 0x01020304);
+		#[cfg(target_endian = "little")]
+		assert!(buffer == [0x04, 0x03, 0x02, 0x01]);
+		#[cfg(target_endian = "big")]
+		assert!(buffer == [0x01, 0x02, 0x03, 0x04]);
+
+		// 0x80000000 - 0x7efdfcfd = 0x01020305
+		Endian::NativeEndian.write_i32(&mut buffer, -0x7efdfcfb);
+		#[cfg(target_endian = "little")]
+		assert!(buffer == [0x05, 0x03, 0x02, 0x81]);
+		#[cfg(target_endian = "big")]
+		assert!(buffer == [0x81, 0x02, 0x03, 0x05]);
+	}
+
 	#[test]
 	fn read_i32_litte_endian_works() {
 		assert!(Endian::LittleEndian.read_i32(&[0x04, 0x03, 0x02, 0x01]) == 0x01020304);
@@ -113,4 +159,18 @@ mod test {
 		// 0x80000000 - 0x7efdfcfd = 0x01020305
 		assert!(Endian::BigEndian.read_i32(&[0x81, 0x02, 0x03, 0x05]) == -0x7efdfcfb);
 	}
+
+	#[test]
+	fn read_i32_native_endian_works() {
+		#[cfg(target_endian = "little")]
+		assert!(Endian::NativeEndian.read_i32(&[0x04, 0x03, 0x02, 0x01]) == 0x01020304);
+		// 0x80000000 - 0x7efdfcfd = 0x01020305
+		#[cfg(target_endian = "little")]
+		assert!(Endian::NativeEndian.read_i32(&[0x05, 0x03, 0x02, 0x81]) == -0x7efdfcfb);
+
+		#[cfg(target_endian = "big")]
+		assert!(Endian::NativeEndian.read_i32(&[0x01, 0x02, 0x03, 0x04]) == 0x01020304);
+		#[cfg(target_endian = "big")]
+		assert!(Endian::NativeEndian.read_i32(&[0x81, 0x02, 0x03, 0x05]) == -0x7efdfcfb);
+	}
 }
diff --git a/src/transport/unix/config.rs b/src/transport/unix/config.rs
index 2adde88..010f04a 100644
--- a/src/transport/unix/config.rs
+++ b/src/transport/unix/config.rs
@@ -40,7 +40,7 @@ impl Default for UnixConfig {
 			max_body_len_write: 4 * 1024,
 			max_fds_read: 10,
 			max_fds_write: 10,
-			endian: Endian::LittleEndian,
+			endian: Endian::NativeEndian,
 		}
 	}
 }