refactor: 将 DTLS 本地依赖迁移到 libs 目录

libs/dtls/src/change_cipher_spec/mod.rs

@@ -0,0 +1,46 @@
+#[cfg(test)]
+mod change_cipher_spec_test;
+
+use std::io::{Read, Write};
+
+use byteorder::{ReadBytesExt, WriteBytesExt};
+
+use super::content::*;
+use super::error::*;
+
+// The change cipher spec protocol exists to signal transitions in
+// ciphering strategies.  The protocol consists of a single message,
+// which is encrypted and compressed under the current (not the pending)
+// connection state.  The message consists of a single byte of value 1.
+/// ## Specifications
+///
+/// * [RFC 5246 §7.1]
+///
+/// [RFC 5246 §7.1]: https://tools.ietf.org/html/rfc5246#section-7.1
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct ChangeCipherSpec;
+
+impl ChangeCipherSpec {
+    pub fn content_type(&self) -> ContentType {
+        ContentType::ChangeCipherSpec
+    }
+
+    pub fn size(&self) -> usize {
+        1
+    }
+
+    pub fn marshal<W: Write>(&self, writer: &mut W) -> Result<()> {
+        writer.write_u8(0x01)?;
+
+        Ok(writer.flush()?)
+    }
+
+    pub fn unmarshal<R: Read>(reader: &mut R) -> Result<Self> {
+        let data = reader.read_u8()?;
+        if data != 0x01 {
+            return Err(Error::ErrInvalidCipherSpec);
+        }
+
+        Ok(ChangeCipherSpec {})
+    }
+}