refactor: 将 DTLS 本地依赖迁移到 libs 目录

libs/dtls/src/compression_methods.rs

@@ -0,0 +1,60 @@
+use std::io::{Read, Write};
+
+use byteorder::{ReadBytesExt, WriteBytesExt};
+
+use crate::error::Result;
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum CompressionMethodId {
+    Null = 0,
+    Unsupported,
+}
+
+impl From<u8> for CompressionMethodId {
+    fn from(val: u8) -> Self {
+        match val {
+            0 => CompressionMethodId::Null,
+            _ => CompressionMethodId::Unsupported,
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct CompressionMethods {
+    pub ids: Vec<CompressionMethodId>,
+}
+
+impl CompressionMethods {
+    pub fn size(&self) -> usize {
+        1 + self.ids.len()
+    }
+
+    pub fn marshal<W: Write>(&self, writer: &mut W) -> Result<()> {
+        writer.write_u8(self.ids.len() as u8)?;
+
+        for id in &self.ids {
+            writer.write_u8(*id as u8)?;
+        }
+
+        Ok(writer.flush()?)
+    }
+
+    pub fn unmarshal<R: Read>(reader: &mut R) -> Result<Self> {
+        let compression_methods_count = reader.read_u8()? as usize;
+        let mut ids = vec![];
+        for _ in 0..compression_methods_count {
+            let id = reader.read_u8()?.into();
+            if id != CompressionMethodId::Unsupported {
+                ids.push(id);
+            }
+        }
+
+        Ok(CompressionMethods { ids })
+    }
+}
+
+pub fn default_compression_methods() -> CompressionMethods {
+    CompressionMethods {
+        ids: vec![CompressionMethodId::Null],
+    }
+}