feat(linux-sandbox): add policy-checked DNS relay

Co-authored-by: Codex noreply@openai.com

codex-rs/network-proxy/src/lib.rs

@@ -47,6 +47,7 @@ pub use network_policy::NetworkPolicyDecision;
 pub use network_policy::NetworkPolicyRequest;
 pub use network_policy::NetworkPolicyRequestArgs;
 pub use network_policy::NetworkProtocol;
+pub use policy::NetworkDomainMatcher;
 pub use policy::normalize_host;
 pub use proxy::ALL_PROXY_ENV_KEYS;
 pub use proxy::ALLOW_LOCAL_BINDING_ENV_KEY;

codex-rs/network-proxy/src/policy.rs

@@ -13,6 +13,8 @@ use std::net::Ipv4Addr;
 use std::net::Ipv6Addr;
 use url::Host as UrlHost;
 
+use crate::proxy::ManagedNetworkDomainPolicy;
+
 /// A normalized host string for policy evaluation.
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct Host(String);
@@ -190,6 +192,23 @@ pub(crate) fn compile_denylist_globset(patterns: &[String]) -> Result<GlobSet> {
     compile_globset_with_policy(patterns, GlobalWildcard::Reject)
 }
 
+/// Compiled managed domain policy for sandbox-side name resolution.
+pub struct NetworkDomainMatcher(GlobSet, GlobSet);
+
+impl NetworkDomainMatcher {
+    pub fn new(policy: &ManagedNetworkDomainPolicy) -> Result<Self> {
+        Ok(Self(
+            compile_allowlist_globset(&policy.allowed_domains)?,
+            compile_denylist_globset(&policy.denied_domains)?,
+        ))
+    }
+
+    pub fn is_allowed(&self, host: &str) -> bool {
+        let host = normalize_host(host);
+        !host.is_empty() && !self.1.is_match(&host) && self.0.is_match(&host)
+    }
+}
+
 fn compile_globset_with_policy(
     patterns: &[String],
     global_wildcard: GlobalWildcard,