Initial commit

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

src/extensions/extension_data/pre_shared_key.rs

@@ -0,0 +1,61 @@
+use crate::buffer::CryptoBuffer;
+
+use crate::ProtocolError;
+use crate::parse_buffer::{ParseBuffer, ParseError};
+
+use heapless::Vec;
+
+#[derive(Debug, Clone, PartialEq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct PreSharedKeyClientHello<'a, const N: usize> {
+    pub identities: Vec<&'a [u8], N>,
+    pub hash_size: usize,
+}
+
+impl<const N: usize> PreSharedKeyClientHello<'_, N> {
+    pub fn parse(_buf: &mut ParseBuffer) -> Result<Self, ParseError> {
+        unimplemented!()
+    }
+
+    pub fn encode(&self, buf: &mut CryptoBuffer) -> Result<(), ProtocolError> {
+        buf.with_u16_length(|buf| {
+            for identity in &self.identities {
+                buf.with_u16_length(|buf| buf.extend_from_slice(identity))
+                    .map_err(|_| ProtocolError::EncodeError)?;
+
+                buf.push_u32(0).map_err(|_| ProtocolError::EncodeError)?;
+            }
+            Ok(())
+        })
+        .map_err(|_| ProtocolError::EncodeError)?;
+
+        let binders_len = (1 + self.hash_size) * self.identities.len();
+        buf.push_u16(binders_len as u16)
+            .map_err(|_| ProtocolError::EncodeError)?;
+
+        for _ in 0..binders_len {
+            buf.push(0).map_err(|_| ProtocolError::EncodeError)?;
+        }
+
+        Ok(())
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct PreSharedKeyServerHello {
+    pub selected_identity: u16,
+}
+
+impl PreSharedKeyServerHello {
+    pub fn parse(buf: &mut ParseBuffer) -> Result<Self, ParseError> {
+        Ok(Self {
+            selected_identity: buf.read_u16()?,
+        })
+    }
+
+    pub fn encode(self, buf: &mut CryptoBuffer) -> Result<(), ProtocolError> {
+        buf.push_u16(self.selected_identity)
+            .map_err(|_| ProtocolError::EncodeError)
+    }
+}