refactor: 将 DTLS 本地依赖迁移到 libs 目录

libs/dtls/src/application_data.rs

@@ -0,0 +1,41 @@
+use std::io::{Read, Write};
+
+use super::content::*;
+use crate::error::Result;
+
+// Application data messages are carried by the record layer and are
+// fragmented, compressed, and encrypted based on the current connection
+// state.  The messages are treated as transparent data to the record
+// layer.
+/// ## Specifications
+///
+/// * [RFC 5246 §10]
+///
+/// [RFC 5246 §10]: https://tools.ietf.org/html/rfc5246#section-10
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct ApplicationData {
+    pub data: Vec<u8>,
+}
+
+impl ApplicationData {
+    pub fn content_type(&self) -> ContentType {
+        ContentType::ApplicationData
+    }
+
+    pub fn size(&self) -> usize {
+        self.data.len()
+    }
+
+    pub fn marshal<W: Write>(&self, writer: &mut W) -> Result<()> {
+        writer.write_all(&self.data)?;
+
+        Ok(writer.flush()?)
+    }
+
+    pub fn unmarshal<R: Read>(reader: &mut R) -> Result<Self> {
+        let mut data: Vec<u8> = vec![];
+        reader.read_to_end(&mut data)?;
+
+        Ok(ApplicationData { data })
+    }
+}