refactor: 将 DTLS 本地依赖迁移到 libs 目录

libs/dtls/src/handshake/handshake_message_client_key_exchange.rs

@@ -0,0 +1,70 @@
+#[cfg(test)]
+mod handshake_message_client_key_exchange_test;
+
+use std::io::{Read, Write};
+
+use byteorder::{BigEndian, WriteBytesExt};
+
+use super::*;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HandshakeMessageClientKeyExchange {
+    pub(crate) identity_hint: Vec<u8>,
+    pub(crate) public_key: Vec<u8>,
+}
+
+impl HandshakeMessageClientKeyExchange {
+    pub fn handshake_type(&self) -> HandshakeType {
+        HandshakeType::ClientKeyExchange
+    }
+
+    pub fn size(&self) -> usize {
+        if !self.public_key.is_empty() {
+            1 + self.public_key.len()
+        } else {
+            2 + self.identity_hint.len()
+        }
+    }
+
+    pub fn marshal<W: Write>(&self, writer: &mut W) -> Result<()> {
+        if (!self.identity_hint.is_empty() && !self.public_key.is_empty())
+            || (self.identity_hint.is_empty() && self.public_key.is_empty())
+        {
+            return Err(Error::ErrInvalidClientKeyExchange);
+        }
+
+        if !self.public_key.is_empty() {
+            writer.write_u8(self.public_key.len() as u8)?;
+            writer.write_all(&self.public_key)?;
+        } else {
+            writer.write_u16::<BigEndian>(self.identity_hint.len() as u16)?;
+            writer.write_all(&self.identity_hint)?;
+        }
+
+        Ok(writer.flush()?)
+    }
+
+    pub fn unmarshal<R: Read>(reader: &mut R) -> Result<Self> {
+        let mut data = vec![];
+        reader.read_to_end(&mut data)?;
+
+        // If parsed as PSK return early and only populate PSK Identity Hint
+        let psk_length = ((data[0] as u16) << 8) | data[1] as u16;
+        if data.len() == psk_length as usize + 2 {
+            return Ok(HandshakeMessageClientKeyExchange {
+                identity_hint: data[2..].to_vec(),
+                public_key: vec![],
+            });
+        }
+
+        let public_key_length = data[0] as usize;
+        if data.len() != public_key_length + 1 {
+            return Err(Error::ErrBufferTooSmall);
+        }
+
+        Ok(HandshakeMessageClientKeyExchange {
+            identity_hint: vec![],
+            public_key: data[1..].to_vec(),
+        })
+    }
+}