Move request/response serialization to YunqMessage trait.

rust/lib/yunq/src/message.rs

@@ -4,6 +4,7 @@ use mammoth::zion::z_cap_t;
 use mammoth::zion::ZError;
 
 pub const MESSAGE_IDENT: u32 = 0x33441122;
+const SENTINEL: u32 = 0xBEEFDEAD;
 pub const MESSAGE_HEADER_SIZE: usize = 24; // 4x uint32, 1x uint64
 
 pub fn field_offset(offset: usize, field_index: usize) -> usize {
@@ -19,12 +20,47 @@ pub trait YunqMessage {
     where
         Self: Sized;
 
+    fn parse_from_request<const N: usize>(
+        buf: &ByteBuffer<N>,
+        caps: &Vec<z_cap_t>,
+    ) -> Result<Self, ZError>
+    where
+        Self: Sized,
+    {
+        if buf.at::<u32>(0)? != SENTINEL {
+            return Err(ZError::INVALID_RESPONSE);
+        }
+
+        let resp_code: u64 = buf.at(8)?;
+        if resp_code != 0 {
+            return Err(ZError::from(resp_code));
+        }
+
+        Ok(Self::parse(&buf, 16, &caps)?)
+    }
+
     fn serialize<const N: usize>(
         &self,
         buf: &mut ByteBuffer<N>,
         offset: usize,
         caps: &mut Vec<z_cap_t>,
     ) -> Result<usize, ZError>;
+
+    fn serialize_as_request<const N: usize>(
+        &self,
+        request_id: u64,
+        buf: &mut ByteBuffer<N>,
+        caps: &mut Vec<z_cap_t>,
+    ) -> Result<usize, ZError> {
+        buf.write_at(0, SENTINEL)?;
+        buf.write_at(8, request_id as u64)?;
+
+        let length = self.serialize(buf, 16, caps)?;
+
+        buf.write_at(4, (16 + length) as u32)?;
+
+        Ok(length + 16)
+    }
 }
 
 pub struct Empty {}