DNS resolution for IPv6

CONTRIBUTING.md

@@ -131,6 +131,21 @@ In order to test IPv6 on a local cluster on macOS, you can use Kind:
 3. `kind create cluster --config kind-config.yaml`
 4. When you run `kubectl get svc -o wide --all-namespaces` you should see IPv6 addresses.
 
+In order to use an agent image from a local registry, you can load the image to kind's registry with:
+
+```
+kind load docker-image test:latest
+```
+
+In order to test on EKS, I used this blueprint: https://github.com/aws-ia/terraform-aws-eks-blueprints/tree/main/patterns/ipv6-eks-cluster
+
+After creating the cluster, I had to give myself permissions to the K8s objects, I did that via the AWS console (in the browser).
+Feel free to add instructions on how to make that "manual" step unnecessary.
+
+IPv6 tests (they currently don't run in the CI):
+- steal_http_ipv6_traffic
+- connect_to_kubernetes_api_service_over_ipv6
+
 
 ### Cleanup
 

changelog.d/2958.added.md

@@ -0,0 +1 @@
+Support for in-cluster DNS resolution of IPv6 addresses.

mirrord/agent/src/dns.rs

@@ -3,7 +3,7 @@ use std::{future, path::PathBuf, time::Duration};
 use futures::{stream::FuturesOrdered, StreamExt};
 use hickory_resolver::{system_conf::parse_resolv_conf, Hosts, Resolver};
 use mirrord_protocol::{
-    dns::{DnsLookup, GetAddrInfoRequest, GetAddrInfoResponse},
+    dns::{DnsLookup, GetAddrInfoRequest, GetAddrInfoRequestV2, GetAddrInfoResponse},
     DnsLookupError, RemoteResult, ResolveErrorKindInternal, ResponseError,
 };
 use tokio::{
@@ -21,9 +21,24 @@ use crate::{
     watched_task::TaskStatus,
 };
 
+#[derive(Debug)]
+pub(crate) enum ClientGetAddrInfoRequest {
+    V1(GetAddrInfoRequest),
+    V2(GetAddrInfoRequestV2),
+}
+
+impl ClientGetAddrInfoRequest {
+    pub(crate) fn into_v2(self) -> GetAddrInfoRequestV2 {
+        match self {
+            ClientGetAddrInfoRequest::V1(old_req) => old_req.into(),
+            ClientGetAddrInfoRequest::V2(v2_req) => v2_req,
+        }
+    }
+}
+
 #[derive(Debug)]
 pub(crate) struct DnsCommand {
-    request: GetAddrInfoRequest,
+    request: ClientGetAddrInfoRequest,
     response_tx: oneshot::Sender<RemoteResult<DnsLookup>>,
 }
 
@@ -34,6 +49,7 @@ pub(crate) struct DnsWorker {
     request_rx: Receiver<DnsCommand>,
     attempts: usize,
     timeout: Duration,
+    support_ipv6: bool,
 }
 
 impl DnsWorker {
@@ -45,7 +61,11 @@ impl DnsWorker {
     /// # Note
     ///
     /// `pid` is used to find the correct path of `etc` directory.
-    pub(crate) fn new(pid: Option<u64>, request_rx: Receiver<DnsCommand>) -> Self {
+    pub(crate) fn new(
+        pid: Option<u64>,
+        request_rx: Receiver<DnsCommand>,
+        support_ipv6: bool,
+    ) -> Self {
         let etc_path = pid
             .map(|pid| {
                 PathBuf::from("/proc")
@@ -66,6 +86,7 @@ impl DnsWorker {
                 .ok()
                 .and_then(|attempts| attempts.parse().ok())
                 .unwrap_or(1),
+            support_ipv6,
         }
     }
 
@@ -79,9 +100,10 @@ impl DnsWorker {
     #[tracing::instrument(level = Level::TRACE, ret, err(level = Level::TRACE))]
     async fn do_lookup(
         etc_path: PathBuf,
-        host: String,
+        request: GetAddrInfoRequestV2,
         attempts: usize,
         timeout: Duration,
+        support_ipv6: bool,
     ) -> RemoteResult<DnsLookup> {
         // Prepares the `Resolver` after reading some `/etc` DNS files.
         //
@@ -94,13 +116,32 @@ impl DnsWorker {
             let hosts_conf = fs::read(hosts_path).await?;
 
             let (config, mut options) = parse_resolv_conf(resolv_conf)?;
+            tracing::debug!(?config, ?options, "parsed config options");
             options.server_ordering_strategy =
                 hickory_resolver::config::ServerOrderingStrategy::UserProvidedOrder;
             options.timeout = timeout;
             options.attempts = attempts;
-            options.ip_strategy = hickory_resolver::config::LookupIpStrategy::Ipv4Only;
+            options.ip_strategy = if support_ipv6 {
+                tracing::debug!("IPv6 support enabled. Respecting client IP family.");
+                request
+                    .family
+                    .try_into()
+                    .inspect_err(|e| {
+                        tracing::error!(%e,
+                        "Unknown address family in addrinfo request. Using IPv4 and IPv6.")
+                    })
+                    // If the agent gets some new, unknown variant of family address, it's the
+                    // client's fault, so the agent queries both IPv4 and IPv6 and if that's not
+                    // good enough for the client, the client can error out.
+                    .unwrap_or(hickory_resolver::config::LookupIpStrategy::Ipv4AndIpv6)
+            } else {
+                tracing::debug!("IPv6 support disabled. Resolving IPv4 only.");
+                hickory_resolver::config::LookupIpStrategy::Ipv4Only
+            };
+            tracing::debug!(?config, ?options, "updated config options");
 
             let mut resolver = Resolver::tokio(config, options);
+            tracing::debug!(?resolver, "tokio resolver");
 
             let mut hosts = Hosts::default();
             hosts.read_hosts_conf(hosts_conf.as_slice())?;
@@ -111,9 +152,10 @@ impl DnsWorker {
 
         let lookup = resolver
             .inspect_err(|fail| tracing::error!(?fail, "Failed to build DNS resolver"))?
-            .lookup_ip(host)
+            .lookup_ip(request.node)
             .await
-            .inspect(|lookup| tracing::trace!(?lookup, "Lookup finished"))?
+            .inspect(|lookup| tracing::trace!(?lookup, "Lookup finished"))
+            .inspect_err(|e| tracing::trace!(%e, "lookup failed"))?
             .into();
 
         Ok(lookup)
@@ -125,8 +167,16 @@ impl DnsWorker {
         let etc_path = self.etc_path.clone();
         let timeout = self.timeout;
         let attempts = self.attempts;
+        let support_ipv6 = self.support_ipv6;
         let lookup_future = async move {
-            let result = Self::do_lookup(etc_path, message.request.node, attempts, timeout).await;
+            let result = Self::do_lookup(
+                etc_path,
+                message.request.into_v2(),
+                attempts,
+                timeout,
+                support_ipv6,
+            )
+            .await;
 
             if let Err(result) = message.response_tx.send(result) {
                 tracing::error!(?result, "Failed to send query response");
@@ -174,7 +224,7 @@ impl DnsApi {
     /// Results of scheduled requests are available via [`Self::recv`] (order is preserved).
     pub(crate) async fn make_request(
         &mut self,
-        request: GetAddrInfoRequest,
+        request: ClientGetAddrInfoRequest,
     ) -> Result<(), AgentError> {
         let (response_tx, response_rx) = oneshot::channel();
 

mirrord/agent/src/entrypoint.rs

@@ -10,7 +10,7 @@ use std::{
 };
 
 use client_connection::AgentTlsConnector;
-use dns::{DnsCommand, DnsWorker};
+use dns::{ClientGetAddrInfoRequest, DnsCommand, DnsWorker};
 use futures::TryFutureExt;
 use mirrord_protocol::{ClientMessage, DaemonMessage, GetEnvVarsRequest, LogMessage};
 use sniffer::tcp_capture::RawSocketTcpCapture;
@@ -433,7 +433,14 @@ impl ClientConnectionHandler {
                     .await?
             }
             ClientMessage::GetAddrInfoRequest(request) => {
-                self.dns_api.make_request(request).await?;
+                self.dns_api
+                    .make_request(ClientGetAddrInfoRequest::V1(request))
+                    .await?;
+            }
+            ClientMessage::GetAddrInfoRequestV2(request) => {
+                self.dns_api
+                    .make_request(ClientGetAddrInfoRequest::V2(request))
+                    .await?;
             }
             ClientMessage::Ping => self.respond(DaemonMessage::Pong).await?,
             ClientMessage::Tcp(message) => {
@@ -613,7 +620,8 @@ async fn start_agent(args: Args) -> Result<()> {
         let cancellation_token = cancellation_token.clone();
         let watched_task = WatchedTask::new(
             DnsWorker::TASK_NAME,
-            DnsWorker::new(state.container_pid(), dns_command_rx).run(cancellation_token),
+            DnsWorker::new(state.container_pid(), dns_command_rx, args.ipv6)
+                .run(cancellation_token),
         );
         let status = watched_task.status();
         let task = run_thread_in_namespace(

mirrord/config/src/feature/network.rs

@@ -10,7 +10,7 @@ use crate::{
     util::MirrordToggleableConfig,
 };
 
-const IPV6_ENV_VAR: &str = "MIRRORD_INCOMING_ENABLE_IPV6";
+const IPV6_ENV_VAR: &str = "MIRRORD_ENABLE_IPV6";
 
 pub mod dns;
 pub mod filter;

mirrord/intproxy/protocol/src/lib.rs

@@ -10,7 +10,7 @@ use std::{
 
 use bincode::{Decode, Encode};
 use mirrord_protocol::{
-    dns::{GetAddrInfoRequest, GetAddrInfoResponse},
+    dns::{GetAddrInfoRequestV2, GetAddrInfoResponse},
     file::*,
     outgoing::SocketAddress,
     tcp::StealType,
@@ -44,7 +44,7 @@ pub enum LayerToProxyMessage {
     /// A file operation request.
     File(FileRequest),
     /// A DNS request.
-    GetAddrInfo(GetAddrInfoRequest),
+    GetAddrInfo(GetAddrInfoRequestV2),
     /// A request to initiate a new outgoing connection.
     OutgoingConnect(OutgoingConnectRequest),
     /// Requests related to incoming connections.
@@ -210,7 +210,7 @@ pub enum ProxyToLayerMessage {
     NewSession(LayerId),
     /// A response to layer's [`FileRequest`].
     File(FileResponse),
-    /// A response to layer's [`GetAddrInfoRequest`].
+    /// A response to layer's [`GetAddrInfoRequestV2`].
     GetAddrInfo(GetAddrInfoResponse),
     /// A response to layer's [`OutgoingConnectRequest`].
     OutgoingConnect(RemoteResult<OutgoingConnectResponse>),
@@ -428,7 +428,7 @@ impl_request!(
 );
 
 impl_request!(
-    req = GetAddrInfoRequest,
+    req = GetAddrInfoRequestV2,
     res = GetAddrInfoResponse,
     req_path = LayerToProxyMessage::GetAddrInfo,
     res_path = ProxyToLayerMessage::GetAddrInfo,

mirrord/intproxy/src/background_tasks.rs

@@ -3,7 +3,7 @@
 //! The proxy utilizes multiple background tasks to split the code into more self-contained parts.
 //! Structs in this module aim to ease managing their state.
 //!
-//! Each background task implement the [`BackgroundTask`] trait, which specifies its properties and
+//! Each background task implements the [`BackgroundTask`] trait, which specifies its properties and
 //! allows for managing groups of related tasks with one [`BackgroundTasks`] instance.
 
 use std::{collections::HashMap, fmt, future::Future, hash::Hash};

mirrord/intproxy/src/lib.rs

@@ -321,6 +321,13 @@ impl IntProxy {
                     .send(FilesProxyMessage::ProtocolVersion(protocol_version.clone()))
                     .await;
 
+                self.task_txs
+                    .simple
+                    .send(SimpleProxyMessage::ProtocolVersion(
+                        protocol_version.clone(),
+                    ))
+                    .await;
+
                 self.task_txs
                     .incoming
                     .send(IncomingProxyMessage::AgentProtocolVersion(protocol_version))

mirrord/intproxy/src/proxies/simple.rs

@@ -5,9 +5,10 @@ use std::collections::HashMap;
 
 use mirrord_intproxy_protocol::{LayerId, MessageId, ProxyToLayerMessage};
 use mirrord_protocol::{
-    dns::{GetAddrInfoRequest, GetAddrInfoResponse},
+    dns::{AddressFamily, GetAddrInfoRequestV2, GetAddrInfoResponse, ADDRINFO_V2_VERSION},
     ClientMessage, DaemonMessage, GetEnvVarsRequest, RemoteResult,
 };
+use semver::Version;
 use thiserror::Error;
 
 use crate::{
@@ -20,10 +21,12 @@ use crate::{
 
 #[derive(Debug)]
 pub enum SimpleProxyMessage {
-    AddrInfoReq(MessageId, LayerId, GetAddrInfoRequest),
+    AddrInfoReq(MessageId, LayerId, GetAddrInfoRequestV2),
     AddrInfoRes(GetAddrInfoResponse),
     GetEnvReq(MessageId, LayerId, GetEnvVarsRequest),
     GetEnvRes(RemoteResult<HashMap<String, String>>),
+    /// Protocol version was negotiated with the agent.
+    ProtocolVersion(Version),
 }
 
 #[derive(Error, Debug)]
@@ -34,10 +37,27 @@ pub struct SimpleProxyError(#[from] UnexpectedAgentMessage);
 /// Run as a [`BackgroundTask`].
 #[derive(Default)]
 pub struct SimpleProxy {
-    /// For [`GetAddrInfoRequest`]s.
+    /// For [`GetAddrInfoRequestV2`]s.
     addr_info_reqs: RequestQueue,
     /// For [`GetEnvVarsRequest`]s.
     get_env_reqs: RequestQueue,
+    /// [`mirrord_protocol`] version negotiated with the agent.
+    /// Determines whether we can use `GetAddrInfoRequestV2`.
+    protocol_version: Option<Version>,
+}
+
+impl SimpleProxy {
+    #[tracing::instrument(skip(self), level = tracing::Level::TRACE)]
+    fn set_protocol_version(&mut self, version: Version) {
+        self.protocol_version.replace(version);
+    }
+
+    /// Returns whether [`mirrord_protocol`] version allows for a V2 addrinfo request.
+    fn addr_info_v2(&self) -> bool {
+        self.protocol_version
+            .as_ref()
+            .is_some_and(|version| ADDRINFO_V2_VERSION.matches(version))
+    }
 }
 
 impl BackgroundTask for SimpleProxy {
@@ -52,9 +72,23 @@ impl BackgroundTask for SimpleProxy {
             match msg {
                 SimpleProxyMessage::AddrInfoReq(message_id, session_id, req) => {
                     self.addr_info_reqs.push_back(message_id, session_id);
-                    message_bus
-                        .send(ClientMessage::GetAddrInfoRequest(req))
-                        .await;
+                    if self.addr_info_v2() {
+                        message_bus
+                            .send(ClientMessage::GetAddrInfoRequestV2(req))
+                            .await;
+                    } else {
+                        if matches!(req.family, AddressFamily::Ipv6Only) {
+                            tracing::warn!(
+                                "The agent version you're using does not support DNS\
+                                queries for IPv6 addresses. This version will only fetch IPv4\
+                                address. Please update to a newer agent image for better IPv6\
+                                support."
+                            )
+                        }
+                        message_bus
+                            .send(ClientMessage::GetAddrInfoRequest(req.into()))
+                            .await;
+                    }
                 }
                 SimpleProxyMessage::AddrInfoRes(res) => {
                     let (message_id, layer_id) =
@@ -88,6 +122,7 @@ impl BackgroundTask for SimpleProxy {
                         })
                         .await
                 }
+                SimpleProxyMessage::ProtocolVersion(version) => self.set_protocol_version(version),
             }
         }
 

mirrord/layer/src/file/ops.rs

@@ -14,7 +14,9 @@ use mirrord_protocol::{
     ResponseError,
 };
 use rand::distributions::{Alphanumeric, DistString};
-use tracing::{error, trace, Level};
+#[cfg(debug_assertions)]
+use tracing::Level;
+use tracing::{error, trace};
 
 use super::{hooks::FN_OPEN, open_dirs::OPEN_DIRS, *};
 #[cfg(target_os = "linux")]