refactor: 将 DTLS 本地依赖迁移到 libs 目录

libs/dtls/src/handshake/handshake_header.rs

@@ -0,0 +1,50 @@
+use std::io::{Read, Write};
+
+use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
+
+use super::*;
+
+// msg_len for Handshake messages assumes an extra 12 bytes for
+// sequence, Fragment and version information
+pub(crate) const HANDSHAKE_HEADER_LENGTH: usize = 12;
+
+#[derive(Copy, Clone, PartialEq, Eq, Debug, Default)]
+pub struct HandshakeHeader {
+    pub(crate) handshake_type: HandshakeType,
+    pub(crate) length: u32, // uint24 in spec
+    pub(crate) message_sequence: u16,
+    pub(crate) fragment_offset: u32, // uint24 in spec
+    pub(crate) fragment_length: u32, // uint24 in spec
+}
+
+impl HandshakeHeader {
+    pub fn size(&self) -> usize {
+        1 + 3 + 2 + 3 + 3
+    }
+
+    pub fn marshal<W: Write>(&self, writer: &mut W) -> Result<()> {
+        writer.write_u8(self.handshake_type as u8)?;
+        writer.write_u24::<BigEndian>(self.length)?;
+        writer.write_u16::<BigEndian>(self.message_sequence)?;
+        writer.write_u24::<BigEndian>(self.fragment_offset)?;
+        writer.write_u24::<BigEndian>(self.fragment_length)?;
+
+        Ok(writer.flush()?)
+    }
+
+    pub fn unmarshal<R: Read>(reader: &mut R) -> Result<Self> {
+        let handshake_type = reader.read_u8()?.into();
+        let length = reader.read_u24::<BigEndian>()?;
+        let message_sequence = reader.read_u16::<BigEndian>()?;
+        let fragment_offset = reader.read_u24::<BigEndian>()?;
+        let fragment_length = reader.read_u24::<BigEndian>()?;
+
+        Ok(HandshakeHeader {
+            handshake_type,
+            length,
+            message_sequence,
+            fragment_offset,
+            fragment_length,
+        })
+    }
+}