radicle/node: Do not error on IPv6 without `[]`

IPv6 addresses are already persisted in `config.json` files.
The parsing of these old addresses, e.g. `FE80::0202:B3FF:FE1E:8329:5976` should remain valid.
Emit a warning when they are found.
The output of the address will still enclose the host in `[]`.

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## Fixed Bugs
+
+- The fix to ambiguous IPv6 addresses, e.g. `::1:8776` vs. `[::1]:8776`,
+  resulted in backward incompatibility. Configuration files containing addresses
+  in the ambiguous format could not be parsed anymore. Partially undo this change
+  to stay backward compatible, but log a warning in case ambiguous addresses are
+  encountered.
+
+## 1.7.0
+
 ## Release Highlights
 
 - The "Signed References" feature was reimplemented. The commits in

crates/radicle/src/node.rs

@@ -548,10 +548,13 @@ impl FromStr for Address {
         {
             HostName::Ip(host.parse::<Ipv6Addr>()?.into())
         } else {
-            // Require IPv6 addresses to always be enclosed in `[` and `]`.
-            host.parse().and_then(|host| match host {
-                HostName::Ip(IpAddr::V6(_)) => Err(AddrParseError::UnknownAddressFormat),
-                host => Ok(host),
+            // Warn on IPv6 addresses that are not enclosed in `[` and `]`.
+            host.parse().map(|host| match host {
+                HostName::Ip(IpAddr::V6(addr)) => {
+                    log::warn!("Address format will change in the future. '{s}' should be changed to '[{addr}]:{port}' to stay compatible. Refer to RFC 5926, Sec. 6 as well as RFC 3986, Sec. D.1. and RFC 2732, Sec. 2.");
+                    host
+                },
+                host => host,
             })?
         };
 
@@ -1525,6 +1528,7 @@ mod test {
         assert!(Address::from_str("[::1]:8776").is_ok());
         assert!(Address::from_str("[::ffff:127.0.0.1]:8776").is_ok());
         assert!(Address::from_str("localhost:8776").is_ok());
+        assert!(Address::from_str("::1:8776").is_ok()); // Backwards-compatibility
 
         assert!(Address::from_str("").is_err());
         assert!(Address::from_str(":").is_err());
@@ -1532,7 +1536,6 @@ mod test {
         assert!(Address::from_str("127.0.0.1:xyz").is_err());
         assert!(Address::from_str("[invalid]:8776").is_err());
         assert!(Address::from_str("[127.0.0.1]:8776").is_err());
-        assert!(Address::from_str("::1:8776").is_err());
     }
 
     #[test]

crates/radicle/src/node/config.rs

@@ -712,7 +712,7 @@ wrapper!(
 #[allow(clippy::unwrap_used)]
 mod test {
     use super::{DefaultSeedingPolicy, Scope};
-    use crate::node::policy;
+    use crate::node::{policy, Alias};
     use serde_json::json;
 
     #[test]
@@ -833,4 +833,32 @@ mod test {
             .unwrap()
         );
     }
+
+    #[test]
+    fn regression_ipv6_address_brackets() {
+        let address = "[2001:db8::1]:5976".to_string();
+        let config = json!({
+            "alias": "radicle",
+            "externalAddresses": [address],
+        });
+        let got: super::Config = serde_json::from_value(config).unwrap();
+        let mut expected = super::Config::new(Alias::new("radicle"));
+        expected.external_addresses = vec![address.parse().unwrap()];
+        assert_eq!(got.alias, expected.alias);
+        assert_eq!(got.external_addresses, expected.external_addresses);
+    }
+
+    #[test]
+    fn regression_ipv6_address_no_brackets() {
+        let address = "2001:db8::1:5976".to_string();
+        let config = json!({
+            "alias": "radicle",
+            "externalAddresses": [address],
+        });
+        let got: super::Config = serde_json::from_value(config).unwrap();
+        let mut expected = super::Config::new(Alias::new("radicle"));
+        expected.external_addresses = vec![address.parse().unwrap()];
+        assert_eq!(got.alias, expected.alias);
+        assert_eq!(got.external_addresses, expected.external_addresses);
+    }
 }