Initial commit

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/extensions/extension_data/key_share.rs

@@ -0,0 +1,128 @@
+use heapless::Vec;
+
+use crate::buffer::CryptoBuffer;
+use crate::extensions::extension_data::supported_groups::NamedGroup;
+
+use crate::ProtocolError;
+use crate::parse_buffer::{ParseBuffer, ParseError};
+
+#[derive(Debug, Clone, PartialEq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct KeyShareServerHello<'a>(pub KeyShareEntry<'a>);
+
+impl<'a> KeyShareServerHello<'a> {
+    pub fn parse(buf: &mut ParseBuffer<'a>) -> Result<Self, ParseError> {
+        Ok(KeyShareServerHello(KeyShareEntry::parse(buf)?))
+    }
+
+    pub fn encode(&self, buf: &mut CryptoBuffer) -> Result<(), ProtocolError> {
+        self.0.encode(buf)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct KeyShareClientHello<'a, const N: usize> {
+    pub client_shares: Vec<KeyShareEntry<'a>, N>,
+}
+
+impl<'a, const N: usize> KeyShareClientHello<'a, N> {
+    pub fn parse(buf: &mut ParseBuffer<'a>) -> Result<Self, ParseError> {
+        let len = buf.read_u16()? as usize;
+        Ok(KeyShareClientHello {
+            client_shares: buf.read_list(len, KeyShareEntry::parse)?,
+        })
+    }
+
+    pub fn encode(&self, buf: &mut CryptoBuffer) -> Result<(), ProtocolError> {
+        buf.with_u16_length(|buf| {
+            for client_share in &self.client_shares {
+                client_share.encode(buf)?;
+            }
+            Ok(())
+        })
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct KeyShareHelloRetryRequest {
+    pub selected_group: NamedGroup,
+}
+
+#[allow(dead_code)]
+impl KeyShareHelloRetryRequest {
+    pub fn parse(buf: &mut ParseBuffer) -> Result<Self, ParseError> {
+        Ok(Self {
+            selected_group: NamedGroup::parse(buf)?,
+        })
+    }
+
+    pub fn encode(&self, buf: &mut CryptoBuffer) -> Result<(), ProtocolError> {
+        self.selected_group.encode(buf)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct KeyShareEntry<'a> {
+    pub(crate) group: NamedGroup,
+    pub(crate) opaque: &'a [u8],
+}
+
+impl<'a> KeyShareEntry<'a> {
+    pub fn parse(buf: &mut ParseBuffer<'a>) -> Result<Self, ParseError> {
+        let group = NamedGroup::parse(buf)?;
+
+        let opaque_len = buf.read_u16()?;
+        let opaque = buf.slice(opaque_len as usize)?;
+
+        Ok(Self {
+            group,
+            opaque: opaque.as_slice(),
+        })
+    }
+
+    pub fn encode(&self, buf: &mut CryptoBuffer) -> Result<(), ProtocolError> {
+        self.group.encode(buf)?;
+
+        buf.with_u16_length(|buf| buf.extend_from_slice(self.opaque))
+            .map_err(|_| ProtocolError::EncodeError)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use std::sync::Once;
+
+    static INIT: Once = Once::new();
+
+    fn setup() {
+        INIT.call_once(|| {
+            env_logger::init();
+        });
+    }
+
+    #[test]
+    fn test_parse_empty() {
+        setup();
+        let buffer = [0x00, 0x17, 0x00, 0x00];
+        let result = KeyShareEntry::parse(&mut ParseBuffer::new(&buffer)).unwrap();
+
+        assert_eq!(NamedGroup::Secp256r1, result.group);
+        assert_eq!(0, result.opaque.len());
+    }
+
+    #[test]
+    fn test_parse() {
+        setup();
+        let buffer = [0x00, 0x17, 0x00, 0x02, 0xAA, 0xBB];
+        let result = KeyShareEntry::parse(&mut ParseBuffer::new(&buffer)).unwrap();
+
+        assert_eq!(NamedGroup::Secp256r1, result.group);
+        assert_eq!(2, result.opaque.len());
+        assert_eq!([0xAA, 0xBB], result.opaque);
+    }
+}