feat(iroh): allow to override provenance for StaticProvider (#3527)

## Description

The `StaticProvider` discovery service has a hard-coded `provenance` of
`static-provider`. When using the StaticProvider as a building block of
protocols or services, it is useful to override it so that the items can
be disambiguated as to from which service they come from.

## Breaking Changes

<!-- Optional, if there are any breaking changes document them,
including how to migrate older code. -->

## Notes & open questions

<!-- Any notes, remarks or open questions you have to make about the PR.
-->

## Change checklist
<!-- Remove any that are not relevant. -->
- [x] Self-review.
- [x] Documentation updates following the [style
guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text),
if relevant.
- [x] Tests if relevant.
- [x] All breaking changes documented.
- [ ] List all breaking changes in the above "Breaking Changes" section.
- [ ] Open an issue or PR on any number0 repos that are affected by this
breaking change. Give guidance on how the updates should be handled or
do the actual updates themselves. The major ones are:
    - [ ] [`quic-rpc`](https://github.com/n0-computer/quic-rpc)
    - [ ] [`iroh-gossip`](https://github.com/n0-computer/iroh-gossip)
    - [ ] [`iroh-blobs`](https://github.com/n0-computer/iroh-blobs)
    - [ ] [`dumbpipe`](https://github.com/n0-computer/dumbpipe)
    - [ ] [`sendme`](https://github.com/n0-computer/sendme)

---------

Co-authored-by: Friedel Ziegelmayer <[email protected]>

Author: Frando

iroh/src/discovery/static_provider.rs

@@ -64,10 +64,19 @@ use super::{Discovery, DiscoveryError, DiscoveryItem, NodeData, NodeInfo};
 /// ```
 ///
 /// [`NodeTicket`]: https://docs.rs/iroh-base/latest/iroh_base/ticket/struct.NodeTicket
-#[derive(Debug, Default, Clone)]
-#[repr(transparent)]
+#[derive(Debug, Clone)]
 pub struct StaticProvider {
     nodes: Arc<RwLock<BTreeMap<NodeId, StoredNodeInfo>>>,
+    provenance: &'static str,
+}
+
+impl Default for StaticProvider {
+    fn default() -> Self {
+        Self {
+            nodes: Default::default(),
+            provenance: Self::PROVENANCE,
+        }
+    }
 }
 
 #[derive(Debug)]
@@ -90,6 +99,20 @@ impl StaticProvider {
         Self::default()
     }
 
+    /// Creates a new static discovery instance with the provided `provenance`.
+    ///
+    /// The provenance is part of [`DiscoveryItem`]s returned from [`Self::resolve`].
+    /// It is mostly used for debugging information and allows understanding the origin of
+    /// addressing information used by an iroh [`Endpoint`].
+    ///
+    /// [`Endpoint`]: crate::Endpoint
+    pub fn with_provenance(provenance: &'static str) -> Self {
+        Self {
+            nodes: Default::default(),
+            provenance,
+        }
+    }
+
     /// Creates a static discovery instance from node addresses.
     ///
     /// # Examples
@@ -196,7 +219,7 @@ impl Discovery for StaticProvider {
                     .as_micros() as u64;
                 let item = DiscoveryItem::new(
                     NodeInfo::from_parts(node_id, node_info.data.clone()),
-                    Self::PROVENANCE,
+                    self.provenance,
                     Some(last_updated),
                 );
                 Some(stream::iter(Some(Ok(item))).boxed())
@@ -248,4 +271,22 @@ mod tests {
 
         Ok(())
     }
+
+    #[tokio::test]
+    async fn test_provenance() -> Result {
+        let discovery = StaticProvider::with_provenance("foo");
+        let key = SecretKey::from_bytes(&[0u8; 32]);
+        let addr = NodeAddr {
+            node_id: key.public(),
+            relay_url: Some("https://example.com".parse()?),
+            direct_addresses: Default::default(),
+        };
+        discovery.add_node_info(addr);
+        let mut stream = discovery.resolve(key.public()).unwrap();
+        let item = stream.next().await.unwrap()?;
+        assert_eq!(item.provenance(), "foo");
+        assert_eq!(item.relay_url(), Some(&("https://example.com".parse()?)));
+
+        Ok(())
+    }
 }