From 23fdb16885d8f4d8a8d95d77d4c5daf1403e0f0f Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Sat, 31 Oct 2026 12:18:52 +0100
Subject: links replies carry clock offsets

---
 src/transport/mod.rs   |  3 +++
 src/transport/paths.rs |  2 +-
 src/transport/wire.rs  | 18 +++++++++++-------
 3 files changed, 15 insertions(+), 8 deletions(-)

(limited to 'src/transport')

diff --git a/src/transport/mod.rs b/src/transport/mod.rs
index 1ce4cd1..048fe31 100644
--- a/src/transport/mod.rs
+++ b/src/transport/mod.rs
@@ -442,6 +442,9 @@ pub(crate) struct Link {
     /// The peer's other transports (`swarm::links::MAX_OTHERS` at most): where else
     /// it proved itself, those paths up.
     pub(crate) others: Vec<OtherPath>,
+    /// How far the peer's clock is ahead of the member's (`paths::ClockOffset`), if
+    /// measured: with every member's, a map of the swarm shows whose clock is off.
+    pub(crate) clock: Option<paths::ClockOffset>,
 }
 
 /// A transport of a link besides the one in use, in a LINKS_REPLY.
diff --git a/src/transport/paths.rs b/src/transport/paths.rs
index 2ef3a12..7ebde70 100644
--- a/src/transport/paths.rs
+++ b/src/transport/paths.rs
@@ -114,7 +114,7 @@ const CLOCK_KEPT: Duration = Duration::from_secs(300);
 /// PONG: `offset_ms`, give or take `within_ms`. The PONG says its sender's time when it
 /// answered, which was after our PING went and before the PONG came: within half the
 /// round trip of its middle, however differently long the two ways took.
-#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct ClockOffset {
     pub(crate) offset_ms: i64,
diff --git a/src/transport/wire.rs b/src/transport/wire.rs
index 3daba0d..46cea4c 100644
--- a/src/transport/wire.rs
+++ b/src/transport/wire.rs
@@ -14,7 +14,7 @@ use super::{EncodedMessage, MessageKind, ParsedMessage};
 
 /// The wire format's version, the first byte of every payload. Bump it with every change
 /// to a message type or a codec (`golden_bytes` fails then).
-pub(crate) const VERSION: u8 = 12;
+pub(crate) const VERSION: u8 = 13;
 
 /// What the second byte of a payload says.
 fn tag(kind: MessageKind) -> u8 {
@@ -444,6 +444,10 @@ pub(crate) fn samples() -> Vec<ParsedMessage> {
                     rtt_us: None,
                     relayed: false,
                 }],
+                clock: Some(crate::transport::paths::ClockOffset {
+                    offset_ms: -2_500,
+                    within_ms: 40,
+                }),
             }],
         }),
     ]
@@ -618,7 +622,7 @@ mod tests {
         });
         assert_eq!(
             hex(&encode(&hello).unwrap()),
-            format!("0c0097a5737761726d{epoch_hex}01c403010203c3{}07", run("04"))
+            format!("0d0097a5737761726d{epoch_hex}01c403010203c3{}07", run("04"))
         );
 
         let reply = ParsedMessage::HelloReply(HelloReply {
@@ -638,7 +642,7 @@ mod tests {
         assert_eq!(
             hex(&encode(&reply).unwrap()),
             format!(
-                "0c0199a5737761726d9192a17091a161{epoch_hex}01c400c2{}05{}",
+                "0d0199a5737761726d9192a17091a161{epoch_hex}01c400c2{}05{}",
                 run("04"),
                 run("06")
             )
@@ -654,7 +658,7 @@ mod tests {
         });
         assert_eq!(
             hex(&encode(&status).unwrap()),
-            format!("0c03969290c400{epoch_hex}01c3c2c2")
+            format!("0d03969290c400{epoch_hex}01c3c2c2")
         );
 
         let who = ParsedMessage::Who(IdentityProof {
@@ -663,7 +667,7 @@ mod tests {
         });
         assert_eq!(
             hex(&encode(&who).unwrap()),
-            format!("0c0692c420{}c440{}", "08".repeat(32), "09".repeat(64))
+            format!("0d0692c420{}c440{}", "08".repeat(32), "09".repeat(64))
         );
         let ParsedMessage::Me(proof) = decode(
             &encode(&ParsedMessage::Me(IdentityProof {
@@ -677,12 +681,12 @@ mod tests {
         };
         assert_eq!((proof.key, proof.signature), ([8; 32], [9; 64]));
 
-        assert_eq!(hex(&encode(&ParsedMessage::Ping(7)).unwrap()), "0c0807");
+        assert_eq!(hex(&encode(&ParsedMessage::Ping(7)).unwrap()), "0d0807");
         let pong = ParsedMessage::Pong {
             nonce: u64::MAX,
             at: crate::clock::UnixMillis(5),
         };
-        assert_eq!(hex(&encode(&pong).unwrap()), "0c0992cfffffffffffffffff05");
+        assert_eq!(hex(&encode(&pong).unwrap()), "0d0992cfffffffffffffffff05");
         let ParsedMessage::Pong { nonce, at } = decode(&[VERSION, 9, 0x92, 0x2a, 0x07]).unwrap()
         else {
             panic!("not a PONG");
-- 
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