1 files changed, 44 insertions, 18 deletions

diff --git a/src/transport/mod.rs b/src/transport/mod.rs
index 29c48d6..52db406 100644
--- a/src/transport/mod.rs
+++ b/src/transport/mod.rs
@@ -12,6 +12,7 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 pub(crate) use crate::document::replica::Epoch;
 
 pub(crate) mod firewall;
+pub(crate) mod identity;
 pub(crate) mod mycelium;
 #[cfg(test)]
 pub(crate) mod sim;
@@ -137,6 +138,31 @@ pub(crate) enum ParsedMessage {
     Ping(Keepalive),
     Pong(Keepalive),
     Blob(BlobMessage),
+    /// Asks the recipient who it is, saying who the sender is (`transport::identity`).
+    Who(IdentityProof),
+    /// Answers a WHO.
+    Me(IdentityProof),
+}
+
+/// A node's proof that it holds the key of its node ID (`identity`), sending from its
+/// transport address to the recipient's: a signature over both addresses
+/// (`transport::identity::signed`). WHO and ME end at the identity layer; the rest of
+/// the node never sees them.
+#[derive(Clone, Serialize, Deserialize)]
+pub(crate) struct IdentityProof {
+    /// The sender's public node key.
+    #[serde(with = "crate::transport::wire::codec::bytes32")]
+    pub(crate) key: [u8; 32],
+    #[serde(with = "crate::transport::wire::codec::bytes64")]
+    pub(crate) signature: [u8; 64],
+}
+
+impl std::fmt::Debug for IdentityProof {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("IdentityProof")
+            .field("key", &Hex(&self.key))
+            .finish_non_exhaustive()
+    }
 }
 
 /// Content-addressed bytes that any node holding them can serve, in chunks
@@ -237,6 +263,8 @@ pub(crate) enum MessageKind {
     Ping,
     Pong,
     Blob,
+    Who,
+    Me,
 }
 
 impl ParsedMessage {
@@ -248,28 +276,23 @@ impl ParsedMessage {
             ParsedMessage::Ping(_) => MessageKind::Ping,
             ParsedMessage::Pong(_) => MessageKind::Pong,
             ParsedMessage::Blob(_) => MessageKind::Blob,
+            ParsedMessage::Who(_) => MessageKind::Who,
+            ParsedMessage::Me(_) => MessageKind::Me,
         }
     }
 
-    /// Every message carries the sender's epoch.
-    pub(crate) fn epoch(&self) -> Epoch {
-        match self {
-            ParsedMessage::Hello(hello) => hello.epoch,
-            ParsedMessage::HelloReply(reply) => reply.epoch,
-            ParsedMessage::Sync(envelope) => envelope.epoch,
-            ParsedMessage::Ping(keepalive) | ParsedMessage::Pong(keepalive) => keepalive.epoch,
-            ParsedMessage::Blob(blob) => blob.epoch,
-        }
-    }
-
-    /// `SyncEnvelope::epoch_seq`, as every message carries it.
-    pub(crate) fn epoch_seq(&self) -> u32 {
+    /// The sender's epoch and `SyncEnvelope::epoch_seq`, as every message carries them
+    /// but WHO and ME (which the node never sees).
+    pub(crate) fn epoch_stamp(&self) -> Option<(Epoch, u32)> {
         match self {
-            ParsedMessage::Hello(hello) => hello.epoch_seq,
-            ParsedMessage::HelloReply(reply) => reply.epoch_seq,
-            ParsedMessage::Sync(envelope) => envelope.epoch_seq,
-            ParsedMessage::Ping(keepalive) | ParsedMessage::Pong(keepalive) => keepalive.epoch_seq,
-            ParsedMessage::Blob(blob) => blob.epoch_seq,
+            ParsedMessage::Hello(hello) => Some((hello.epoch, hello.epoch_seq)),
+            ParsedMessage::HelloReply(reply) => Some((reply.epoch, reply.epoch_seq)),
+            ParsedMessage::Sync(envelope) => Some((envelope.epoch, envelope.epoch_seq)),
+            ParsedMessage::Ping(keepalive) | ParsedMessage::Pong(keepalive) => {
+                Some((keepalive.epoch, keepalive.epoch_seq))
+            }
+            ParsedMessage::Blob(blob) => Some((blob.epoch, blob.epoch_seq)),
+            ParsedMessage::Who(_) | ParsedMessage::Me(_) => None,
         }
     }
 }
@@ -472,6 +495,9 @@ impl std::fmt::Debug for SyncPayload {
 #[derive(Clone, Debug)]
 pub(crate) struct EncodedMessage {
     pub(crate) peer: String,
+    /// Where the transport sends it: `peer` itself for a transport whose identities are
+    /// addresses, the peer's address under the identity layer (`transport::identity`).
+    pub(crate) address: String,
     pub(crate) body: bytes::Bytes,
     pub(crate) kind: MessageKind,
     /// Bytes the message takes on the wire (without the transport's own framing).