Begin creation of response

7 files changed, 164 insertions, 94 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 354f8aa..2d27e3d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,6 +3,7 @@ name = "wg-handshake"
 version = "0.1.0"
 authors = ["Mathias Hall-Andersen <mathias@hall-andersen.dk>"]
 edition = "2018"
+license = "GPL-3.0"
 
 [dependencies]
 rand = "0.6.5"
diff --git a/src/device.rs b/src/device.rs
index 85adc69..0635a5e 100644
--- a/src/device.rs
+++ b/src/device.rs
@@ -60,13 +60,13 @@ impl Device {
 
         // map : pk -> new index
 
-        self.pkmap.insert(*pk.as_bytes(), self.peers.len());
+        let idx = self.peers.len();
+        self.pkmap.insert(*pk.as_bytes(), idx);
 
         // map : new index -> peer
 
         self.peers.push(Peer::new(
-            pk,
-            self.sk.diffie_hellman(&pk)
+            idx, pk, self.sk.diffie_hellman(&pk)
         ));
 
         Ok(())
@@ -115,19 +115,12 @@ impl Device {
             None => Err(HandshakeError::UnknownPublicKey),
             Some(&idx) => {
                 let peer = &self.peers[idx];
-                let id = self.allocate(idx);
-                noise::create_initiation(self, peer, id)
+                let sender = self.allocate(idx);
+                noise::create_initiation(self, peer, sender)
             }
         }
     }
 
-    pub fn lookup(&self, pk : &PublicKey) -> Result<&Peer, HandshakeError> {
-        match self.pkmap.get(pk.as_bytes()) {
-            Some(&idx) => Ok(&self.peers[idx]),
-            _ => Err(HandshakeError::UnknownPublicKey)
-        }
-    }
-
     /// Process a handshake message.
     ///
     /// # Arguments
@@ -136,7 +129,17 @@ impl Device {
     pub fn process(&self, msg : &[u8]) -> Result<Output, HandshakeError> {
         match msg.get(0) {
             Some(&messages::TYPE_INITIATION) => {
-                noise::process_initiation(self, msg)
+                // consume the initiation
+                let (peer, receiver, hs, ck) = noise::consume_initiation(self, msg)?;
+
+                // allocate index for response
+                let sender = self.allocate(peer.idx);
+
+                // create response
+                noise::create_response(self, peer, sender, receiver, hs, ck).map_err(|e| {
+                    self.release(sender);
+                    e
+                })
             },
             Some(&messages::TYPE_RESPONSE) => {
                 Err(HandshakeError::InvalidMessageFormat)
@@ -144,6 +147,13 @@ impl Device {
             _ => Err(HandshakeError::InvalidMessageFormat)
         }
     }
+
+    pub fn lookup(&self, pk : &PublicKey) -> Result<&Peer, HandshakeError> {
+        match self.pkmap.get(pk.as_bytes()) {
+            Some(&idx) => Ok(&self.peers[idx]),
+            _ => Err(HandshakeError::UnknownPublicKey)
+        }
+    }
 }
 
 impl Device {
diff --git a/src/lib.rs b/src/lib.rs
index ee22a9b..e2d9b8d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,3 +4,7 @@ mod messages;
 mod peer;
 mod device;
 mod timestamp;
+
+// publicly exposed interface
+
+pub use device::Device;
diff --git a/src/messages.rs b/src/messages.rs
index da26e48..52a3393 100644
--- a/src/messages.rs
+++ b/src/messages.rs
@@ -11,10 +11,12 @@ const SIZE_TIMESTAMP : usize = 12;
 pub const TYPE_INITIATION : u8 = 1;
 pub const TYPE_RESPONSE : u8 = 2;
 
-
-/* Wireguard handshake (noise) initiation message
- * initator -> responder
+/* Functions related to the packing / unpacking of
+ * the fixed-sized noise handshake messages.
+ *
+ * The unpacked types are unexposed implementation details.
  */
+
 #[repr(C)]
 #[derive(Copy, Clone)]
 pub struct Initiation {
@@ -83,15 +85,6 @@ impl Into<Vec<u8>> for Initiation {
     }
 }
 
-impl fmt::Debug for Initiation {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f,
-            "MessageInitiation {{ type = {} }}",
-            self.f_type
-        )
-    }
-}
-
 impl Default for Initiation {
     fn default() -> Self {
         Self {
@@ -106,6 +99,15 @@ impl Default for Initiation {
     }
 }
 
+impl fmt::Debug for Initiation {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f,
+            "MessageInitiation {{ type = {} }}",
+            self.f_type
+        )
+    }
+}
+
 #[cfg(test)]
 impl PartialEq for Initiation {
     fn eq(&self, other: &Self) -> bool {
@@ -122,10 +124,6 @@ impl PartialEq for Initiation {
 #[cfg(test)]
 impl Eq for Initiation {}
 
-
-/* Wireguard handshake (noise) responder message
- * responder -> initator
- */
 #[repr(C)]
 #[derive(Copy, Clone)]
 pub struct Response {
@@ -194,6 +192,19 @@ impl Into<Vec<u8>> for Response {
     }
 }
 
+impl Default for Response {
+    fn default() -> Self {
+        Self {
+            f_type      : TYPE_RESPONSE as u32,
+            f_sender    : 0,
+            f_receiver  : 0,
+            f_ephemeral : [0u8; SIZE_X25519_POINT],
+            f_empty_tag : [0u8; SIZE_TAG]
+        }
+    }
+}
+
+
 impl fmt::Debug for Response {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f,
@@ -220,23 +231,20 @@ mod tests {
 
     #[test]
     fn message_response_identity() {
-        let msg = Response {
-            f_type : TYPE_RESPONSE as u32,
-            f_sender : 146252,
-            f_receiver : 554442,
-            f_ephemeral : [
-                // ephemeral public key
-                0xc1, 0x66, 0x0a, 0x0c, 0xdc, 0x0f, 0x6c, 0x51,
-                0x0f, 0xc2, 0xcc, 0x51, 0x52, 0x0c, 0xde, 0x1e,
-                0xf7, 0xf1, 0xca, 0x90, 0x86, 0x72, 0xad, 0x67,
-                0xea, 0x89, 0x45, 0x44, 0x13, 0x56, 0x52, 0x1f
-            ],
-            f_empty_tag : [
-                // tag
-                0x60, 0x0e, 0x1e, 0x95, 0x41, 0x6b, 0x52, 0x05,
-                0xa2, 0x09, 0xe1, 0xbf, 0x40, 0x05, 0x2f, 0xde
-            ]
-        };
+        let mut msg : Response = Default::default();
+
+        msg.f_sender = 146252;
+        msg.f_receiver = 554442;
+        msg.f_ephemeral = [
+            0xc1, 0x66, 0x0a, 0x0c, 0xdc, 0x0f, 0x6c, 0x51,
+            0x0f, 0xc2, 0xcc, 0x51, 0x52, 0x0c, 0xde, 0x1e,
+            0xf7, 0xf1, 0xca, 0x90, 0x86, 0x72, 0xad, 0x67,
+            0xea, 0x89, 0x45, 0x44, 0x13, 0x56, 0x52, 0x1f
+        ];
+        msg.f_empty_tag = [
+            0x60, 0x0e, 0x1e, 0x95, 0x41, 0x6b, 0x52, 0x05,
+            0xa2, 0x09, 0xe1, 0xbf, 0x40, 0x05, 0x2f, 0xde
+        ];
 
         let buf : Vec<u8> = msg.into();
         let msg_p : Response = Response::try_from(&buf[..]).unwrap();
@@ -245,39 +253,33 @@ mod tests {
 
     #[test]
     fn message_initiate_identity() {
-        let msg = Initiation {
-            f_type : TYPE_INITIATION as u32,
-            f_sender : 575757,
-            f_ephemeral : [
-                // ephemeral public key
-                0xc1, 0x66, 0x0a, 0x0c, 0xdc, 0x0f, 0x6c, 0x51,
-                0x0f, 0xc2, 0xcc, 0x51, 0x52, 0x0c, 0xde, 0x1e,
-                0xf7, 0xf1, 0xca, 0x90, 0x86, 0x72, 0xad, 0x67,
-                0xea, 0x89, 0x45, 0x44, 0x13, 0x56, 0x52, 0x1f
-            ],
-            f_static : [
-                // encrypted static public key
-                0xdc, 0x33, 0x90, 0x15, 0x8f, 0x82, 0x3e, 0x06,
-                0x44, 0xa0, 0xde, 0x4c, 0x15, 0x6c, 0x5d, 0xa4,
-                0x65, 0x99, 0xf6, 0x6c, 0xa1, 0x14, 0x77, 0xf9,
-                0xeb, 0x6a, 0xec, 0xc3, 0x3c, 0xda, 0x47, 0xe1
-            ],
-            f_static_tag : [
-                // poly1305 tag
-                0x45, 0xac, 0x8d, 0x43, 0xea, 0x1b, 0x2f, 0x02,
-                0x45, 0x5d, 0x86, 0x37, 0xee, 0x83, 0x6b, 0x42
-            ],
-            f_timestamp : [
-                // timestamp
-                0x4f, 0x1c, 0x60, 0xec, 0x0e, 0xf6, 0x36, 0xf0,
-                0x78, 0x28, 0x57, 0x42
-            ],
-            f_timestamp_tag : [
-                // poly1305 tag
-                0x60, 0x0e, 0x1e, 0x95, 0x41, 0x6b, 0x52, 0x05,
-                0xa2, 0x09, 0xe1, 0xbf, 0x40, 0x05, 0x2f, 0xde
-            ]
-        };
+        let mut msg : Initiation = Default::default();
+
+        msg.f_sender = 575757;
+        msg.f_ephemeral = [
+            0xc1, 0x66, 0x0a, 0x0c, 0xdc, 0x0f, 0x6c, 0x51,
+            0x0f, 0xc2, 0xcc, 0x51, 0x52, 0x0c, 0xde, 0x1e,
+            0xf7, 0xf1, 0xca, 0x90, 0x86, 0x72, 0xad, 0x67,
+            0xea, 0x89, 0x45, 0x44, 0x13, 0x56, 0x52, 0x1f
+        ];
+        msg.f_static = [
+            0xdc, 0x33, 0x90, 0x15, 0x8f, 0x82, 0x3e, 0x06,
+            0x44, 0xa0, 0xde, 0x4c, 0x15, 0x6c, 0x5d, 0xa4,
+            0x65, 0x99, 0xf6, 0x6c, 0xa1, 0x14, 0x77, 0xf9,
+            0xeb, 0x6a, 0xec, 0xc3, 0x3c, 0xda, 0x47, 0xe1
+        ];
+        msg.f_static_tag = [
+            0x45, 0xac, 0x8d, 0x43, 0xea, 0x1b, 0x2f, 0x02,
+            0x45, 0x5d, 0x86, 0x37, 0xee, 0x83, 0x6b, 0x42
+        ];
+        msg.f_timestamp = [
+            0x4f, 0x1c, 0x60, 0xec, 0x0e, 0xf6, 0x36, 0xf0,
+            0x78, 0x28, 0x57, 0x42
+        ];
+        msg.f_timestamp_tag = [
+            0x60, 0x0e, 0x1e, 0x95, 0x41, 0x6b, 0x52, 0x05,
+            0xa2, 0x09, 0xe1, 0xbf, 0x40, 0x05, 0x2f, 0xde
+        ];
 
         let buf : Vec<u8> = msg.into();
         assert_eq!(msg, Initiation::try_from(&buf[..]).unwrap());
diff --git a/src/noise.rs b/src/noise.rs
index 9de03cd..9f127e8 100644
--- a/src/noise.rs
+++ b/src/noise.rs
@@ -14,6 +14,9 @@ use crypto::aead::{AeadEncryptor,AeadDecryptor};
 
 use rand::rngs::OsRng;
 
+use generic_array::typenum::U32;
+use generic_array::GenericArray;
+
 use crate::types::*;
 use crate::peer::{State, Peer};
 use crate::device::Device;
@@ -248,7 +251,10 @@ pub fn create_initiation(
     Ok(Initiation::into(msg))
 }
 
-pub fn process_initiation(device : &Device, msg : &[u8]) -> Result<Output, HandshakeError> {
+pub fn consume_initiation<'a>(
+    device : &'a Device,
+    msg : &[u8]
+) -> Result<(&'a Peer, u32, GenericArray<u8, U32>, GenericArray<u8, U32>), HandshakeError> {
 
     // parse message
 
@@ -310,15 +316,27 @@ pub fn process_initiation(device : &Device, msg : &[u8]) -> Result<Output, Hands
         &msg.f_timestamp_tag // tag
     )?;
 
-    // update state of peer
+    // check and update timestamp
 
-    peer.set_state_timestamp(
-        State::InitiationSent{
-            hs : hs,
-            ck : ck
-        },
-        &ts
-    )?;
+    peer.check_timestamp(&ts)?;
+
+    // return state (to create response)
+
+    Ok((peer, msg.f_sender, hs, ck))
+}
+
+pub fn create_response(
+    device   : &Device,
+    peer     : &Peer,
+    sender   : u32,
+    receiver : u32,
+    hs       : GenericArray<u8, U32>,
+    ck       : GenericArray<u8, U32>
+) -> Result<Output, HandshakeError> {
+
+    let mut msg : Response = Default::default();
+
+    // parse message
 
     Ok(Output(None, None))
 }
diff --git a/src/peer.rs b/src/peer.rs
index 6c4bb3c..e656d56 100644
--- a/src/peer.rs
+++ b/src/peer.rs
@@ -9,7 +9,14 @@ use x25519_dalek::SharedSecret;
 use crate::types::*;
 use crate::timestamp;
 
+/* Represents the recomputation and state of a peer.
+ *
+ * This type is only for internal use and not exposed.
+ */
+
 pub struct Peer {
+    pub idx   : usize,
+
     // mutable state
     state     : Mutex<State>,
     timestamp : Mutex<Option<timestamp::TAI64N>>,
@@ -31,10 +38,12 @@ pub enum State {
 
 impl Peer {
     pub fn new(
+        idx : usize,
         pk  : PublicKey,    // public key of peer
         ss  : SharedSecret  // precomputed DH(static, static)
     ) -> Self {
         Self {
+            idx       : idx,
             state     : Mutex::new(State::Reset),
             timestamp : Mutex::new(None),
             pk        : pk,
@@ -62,6 +71,28 @@ impl Peer {
         *state = state_new;
     }
 
+    /// # Arguments
+    ///
+    /// * ts_new - The timestamp
+    ///
+    /// # Returns
+    ///
+    /// A Boolean indicating if the state was updated
+    pub fn check_timestamp(&self,
+                           timestamp_new : &timestamp::TAI64N) -> Result<(), HandshakeError> {
+
+        let mut timestamp = self.timestamp.lock().unwrap();
+        match *timestamp {
+            None => Ok(()),
+            Some(timestamp_old) => if timestamp::compare(&timestamp_old, &timestamp_new) {
+                *timestamp = Some(*timestamp_new);
+                Ok(())
+            } else {
+                Err(HandshakeError::OldTimestamp)
+            }
+        }
+    }
+
     /// Set the mutable state of the peer conditioned on the timestamp being newer
     ///
     /// # Arguments
diff --git a/src/types.rs b/src/types.rs
index 464ad81..a2a7cdd 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,11 +1,6 @@
 use std::fmt;
 use std::error::Error;
 
-use x25519_dalek::PublicKey;
-use x25519_dalek::SharedSecret;
-
-use crate::timestamp;
-
 // config error
 
 #[derive(Debug)]
@@ -45,7 +40,16 @@ pub enum HandshakeError {
 
 impl fmt::Display for HandshakeError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "HandshakeError")
+        match self {
+            HandshakeError::DecryptionFailure =>
+                write!(f, "Failed to AEAD:OPEN"),
+            HandshakeError::UnknownPublicKey =>
+                write!(f, "Unknown public key"),
+            HandshakeError::InvalidMessageFormat =>
+                write!(f, "Invalid handshake message format"),
+            HandshakeError::OldTimestamp =>
+                write!(f, "Timestamp is less/equal to the newest")
+        }
     }
 }