Update hickory, adapt code (#2971)

* Update hickory-resolver version.

Also: change renamed feature name (see hickory-dns/hickory-dns@c96a234)

* Make some adaptations because SemVer lost its meaning

* More changes for ZeroVersioned dependency minor bump

* Cargo.lock after rebase

* changelog

* More changes for a dependency's "minor" version

Also, added to CONTRIBUTING.md how to check agent code on macOS.

CONTRIBUTING.md

@@ -512,3 +512,27 @@ If you're using rust-analyzer VSCode extension, put this block in `.vscode/setti
     ]
 }
 ```
+
+You can use `cargo-zigbuild` to run `cargo check` or `clippy` on the agent's code on macOS.
+
+`cargo check`
+
+```shell
+cargo-zigbuild check -p mirrord-agent --target x86_64-unknown-linux-gnu
+```
+
+`clippy` only for the agent
+
+```shell
+cargo-zigbuild clippy --target x86_64-unknown-linux-gnu -p mirrord-agent -- -Wclippy::indexing_slicing -D warnings
+```
+
+`clippy` for all code:
+
+```shell
+cargo-zigbuild clippy --lib --bins --all-features --target x86_64-unknown-linux-gnu --tests -- -Wclippy::indexing_slicing -D warnings
+```
+
+If it doesn't work, try updating `cargo-zigbuild`
+(`cargo install cargo-zigbuild` or maybe `cargo install cargo-zigbuild --force`)
+or via `homebrew` if it was installed via homebrew.

Cargo.toml

@@ -89,10 +89,11 @@ kube = { git = "https://github.com/kube-rs/kube.git", rev = "ecbdafc214538aadc78
     "socks5",
     "http-proxy",
 ] }
-hickory-resolver = { version = "0.24", features = [
-    "serde-config",
+hickory-resolver = { version = "0.25.0-alpha.4", features = [
+    "serde",
     "tokio-runtime",
 ] }
+hickory-proto = "0.25.0-alpha.4"
 tokio-util = { version = "0.7", features = ["net", "codec"] }
 
 # Used by `layer`, `intproxy`, `tests`, `medschool`, `cli`, `agent`, `operator`.

changelog.d/+update-deps.internal.md

@@ -0,0 +1 @@
+Update hickory dependency version.

mirrord/agent/src/dns.rs

@@ -1,7 +1,7 @@
 use std::{future, path::PathBuf, time::Duration};
 
 use futures::{stream::FuturesOrdered, StreamExt};
-use hickory_resolver::{system_conf::parse_resolv_conf, AsyncResolver, Hosts};
+use hickory_resolver::{system_conf::parse_resolv_conf, Hosts, Resolver};
 use mirrord_protocol::{
     dns::{DnsLookup, GetAddrInfoRequest, GetAddrInfoResponse},
     DnsLookupError, RemoteResult, ResolveErrorKindInternal, ResponseError,
@@ -69,21 +69,21 @@ impl DnsWorker {
         }
     }
 
-    /// Reads `/etc/resolv.conf` and `/etc/hosts` files, then uses [`AsyncResolver`] to resolve
-    /// address of the given `host`.
+    /// Reads `/etc/resolv.conf` and `/etc/hosts` files, then uses [`hickory_resolver::Resolver`] to
+    /// resolve address of the given `host`.
     ///
     /// # TODO
     ///
     /// We could probably cache results here.
-    /// We cannot cache the [`AsyncResolver`] itself, becaues the configuration in `etc` may change.
+    /// We cannot cache the [`Resolver`] itself, becaues the configuration in `etc` may change.
     #[tracing::instrument(level = Level::TRACE, ret, err(level = Level::TRACE))]
     async fn do_lookup(
         etc_path: PathBuf,
         host: String,
         attempts: usize,
         timeout: Duration,
     ) -> RemoteResult<DnsLookup> {
-        // Prepares the `AsyncResolver` after reading some `/etc` DNS files.
+        // Prepares the `Resolver` after reading some `/etc` DNS files.
         //
         // We care about logging these errors, at an `error!` level.
         let resolver: Result<_, ResponseError> = try {
@@ -100,9 +100,10 @@ impl DnsWorker {
             options.attempts = attempts;
             options.ip_strategy = hickory_resolver::config::LookupIpStrategy::Ipv4Only;
 
-            let mut resolver = AsyncResolver::tokio(config, options);
+            let mut resolver = Resolver::tokio(config, options);
 
-            let hosts = Hosts::default().read_hosts_conf(hosts_conf.as_slice())?;
+            let mut hosts = Hosts::default();
+            hosts.read_hosts_conf(hosts_conf.as_slice())?;
             resolver.set_hosts(Some(hosts));
 
             resolver

mirrord/protocol/Cargo.toml

@@ -21,6 +21,7 @@ actix-codec.workspace = true
 bytes.workspace = true
 thiserror.workspace = true
 hickory-resolver.workspace = true
+hickory-proto.workspace = true
 serde.workspace = true
 bincode.workspace = true
 tracing.workspace = true

mirrord/protocol/src/dns.rs

@@ -28,12 +28,10 @@ impl From<LookupIp> for DnsLookup {
                     name_labels, rdata, ..
                 } = record.into_parts();
 
-                rdata
-                    .and_then(|rdata| rdata.ip_addr())
-                    .map(|ip| LookupRecord {
-                        name: name_labels.to_string(),
-                        ip,
-                    })
+                rdata.ip_addr().map(|ip| LookupRecord {
+                    name: name_labels.to_string(),
+                    ip,
+                })
             })
             .collect::<Vec<_>>();