Adds mobile async callback hooks

client/internal/dns/resutil/resolve.go

@@ -14,6 +14,10 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+// errNoSuitableAddress mirrors the unexported error string the net package
+// uses when a resolved host has no addresses of the requested family.
+const errNoSuitableAddress = "no suitable address found"
+
 // GenerateRequestID creates a random 8-character hex string for request tracing.
 func GenerateRequestID() string {
 	bytes := make([]byte, 4)
@@ -126,6 +130,14 @@ func LookupIP(ctx context.Context, r resolver, network, host string, qtype uint1
 }
 
 func getRcodeForError(ctx context.Context, r resolver, host string, qtype uint16, err error) int {
+	// The net package returns this AddrError when the host resolves but has
+	// no addresses of the requested family. The domain exists, so answer
+	// NODATA instead of SERVFAIL.
+	var addrErr *net.AddrError
+	if errors.As(err, &addrErr) && addrErr.Err == errNoSuitableAddress {
+		return dns.RcodeSuccess
+	}
+
 	var dnsErr *net.DNSError
 	if !errors.As(err, &dnsErr) {
 		return dns.RcodeServerFailure

client/internal/dns/resutil/resolve_test.go

@@ -0,0 +1,122 @@
+package resutil
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/netip"
+	"testing"
+
+	"github.com/miekg/dns"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type mockResolver struct {
+	// results maps network ("ip4"/"ip6") to the lookup outcome.
+	results map[string]mockLookup
+}
+
+type mockLookup struct {
+	ips []netip.Addr
+	err error
+}
+
+func (m *mockResolver) LookupNetIP(_ context.Context, network, _ string) ([]netip.Addr, error) {
+	res, ok := m.results[network]
+	if !ok {
+		return nil, errors.New("unexpected network: " + network)
+	}
+	return res.ips, res.err
+}
+
+func TestLookupIP_Success(t *testing.T) {
+	r := &mockResolver{results: map[string]mockLookup{
+		"ip4": {ips: []netip.Addr{netip.MustParseAddr("::ffff:192.0.2.1")}},
+	}}
+
+	result := LookupIP(context.Background(), r, "ip4", "example.com.", dns.TypeA)
+
+	assert.Equal(t, dns.RcodeSuccess, result.Rcode, "successful lookup should return NOERROR")
+	require.Len(t, result.IPs, 1, "should return the resolved address")
+	assert.Equal(t, netip.MustParseAddr("192.0.2.1"), result.IPs[0], "v4-mapped address should be unmapped")
+}
+
+func TestLookupIP_NoSuitableAddress(t *testing.T) {
+	// The net package returns this AddrError when the host resolves but has
+	// no addresses of the requested family (e.g. AAAA query for a v4-only
+	// hosts file entry). The domain exists, so this is NODATA, not SERVFAIL.
+	r := &mockResolver{results: map[string]mockLookup{
+		"ip6": {err: &net.AddrError{Err: "no suitable address found", Addr: "example.com."}},
+	}}
+
+	result := LookupIP(context.Background(), r, "ip6", "example.com.", dns.TypeAAAA)
+
+	assert.Equal(t, dns.RcodeSuccess, result.Rcode, "no suitable address should map to NODATA")
+	assert.Empty(t, result.IPs, "NODATA response should carry no addresses")
+}
+
+// TestErrNoSuitableAddressMatchesNetPackage pins our copy of the error string
+// to what the net package actually emits. A literal IP of the wrong family
+// takes the same filterAddrList path as a resolved hostname, without network
+// access.
+func TestErrNoSuitableAddressMatchesNetPackage(t *testing.T) {
+	_, err := (&net.Resolver{}).LookupNetIP(context.Background(), "ip6", "192.0.2.1")
+	require.Error(t, err)
+
+	var addrErr *net.AddrError
+	require.ErrorAs(t, err, &addrErr, "wrong-family lookup should return AddrError")
+	assert.Equal(t, errNoSuitableAddress, addrErr.Err, "net package error string should match our constant")
+}
+
+func TestLookupIP_OtherAddrError(t *testing.T) {
+	r := &mockResolver{results: map[string]mockLookup{
+		"ip4": {err: &net.AddrError{Err: "some other address problem", Addr: "example.com."}},
+	}}
+
+	result := LookupIP(context.Background(), r, "ip4", "example.com.", dns.TypeA)
+
+	assert.Equal(t, dns.RcodeServerFailure, result.Rcode, "unrecognized AddrError should map to SERVFAIL")
+}
+
+func TestLookupIP_NotFoundNXDomain(t *testing.T) {
+	r := &mockResolver{results: map[string]mockLookup{
+		"ip4": {err: &net.DNSError{Err: "no such host", Name: "example.com.", IsNotFound: true}},
+		"ip6": {err: &net.DNSError{Err: "no such host", Name: "example.com.", IsNotFound: true}},
+	}}
+
+	result := LookupIP(context.Background(), r, "ip4", "example.com.", dns.TypeA)
+
+	assert.Equal(t, dns.RcodeNameError, result.Rcode, "not found for both families should map to NXDOMAIN")
+}
+
+func TestLookupIP_NotFoundNoData(t *testing.T) {
+	r := &mockResolver{results: map[string]mockLookup{
+		"ip6": {err: &net.DNSError{Err: "no such host", Name: "example.com.", IsNotFound: true}},
+		"ip4": {ips: []netip.Addr{netip.MustParseAddr("192.0.2.1")}},
+	}}
+
+	result := LookupIP(context.Background(), r, "ip6", "example.com.", dns.TypeAAAA)
+
+	assert.Equal(t, dns.RcodeSuccess, result.Rcode, "not found with the other family present should map to NODATA")
+}
+
+func TestLookupIP_GenericError(t *testing.T) {
+	r := &mockResolver{results: map[string]mockLookup{
+		"ip4": {err: errors.New("connection refused")},
+	}}
+
+	result := LookupIP(context.Background(), r, "ip4", "example.com.", dns.TypeA)
+
+	assert.Equal(t, dns.RcodeServerFailure, result.Rcode, "generic error should map to SERVFAIL")
+}
+
+func TestLookupIP_DNSErrorNotIsNotFound(t *testing.T) {
+	r := &mockResolver{results: map[string]mockLookup{
+		"ip4": {err: &net.DNSError{Err: "server misbehaving", Name: "example.com.", IsTemporary: true}},
+	}}
+
+	result := LookupIP(context.Background(), r, "ip4", "example.com.", dns.TypeA)
+
+	assert.Equal(t, dns.RcodeServerFailure, result.Rcode, "upstream failure should map to SERVFAIL")
+}

client/mdm/policy_mobile.go

@@ -2,13 +2,41 @@
 
 package mdm
 
-// loadPlatformPolicy is unused on mobile: the native layer (Swift on iOS,
-// Kotlin/Java on Android) reads the OS managed-config store and pushes the
-// resulting dictionary in-process via a gomobile entry point that lands in
-// Phase 5 / Phase 6. The stub keeps the package compilable for mobile
-// builds and returns (nil, nil) — the platform-absent sentinel that
-// LoadPolicy in policy.go treats as "no MDM source present".
-func loadPlatformPolicy() (map[string]any, error) {
-	//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see LoadPolicy.
-	return nil, nil
+// PolicyFetcher is the bridge between Go and the mobile native layer
+// (Kotlin/Java on Android, Swift on iOS). The native layer registers
+// an implementation at gomobile init via SetMobilePolicyFetcher;
+// thereafter every call to loadPlatformPolicy delegates to the
+// registered fetcher, which reads the OS-native managed-config store
+// (RestrictionsManager on Android, com.apple.configuration.managed
+// UserDefaults on iOS) and returns the current snapshot.
+//
+// Set-once at init, never mutated at runtime → no synchronisation
+// required for the read path. The native layer must register before
+// any Go code starts polling or processing MDM events.
+type PolicyFetcher interface {
+	Fetch() map[string]any
+}
+
+var fetcher PolicyFetcher
+
+// SetMobilePolicyFetcher registers the native-provided fetcher. Call
+// exactly once from the gomobile init code (Kotlin Application.onCreate
+// / Swift AppDelegate) before the daemon starts. Passing nil disables
+// MDM enforcement on this build (loadPlatformPolicy returns
+// (nil, nil) — the platform-absent sentinel that LoadPolicy treats as
+// "no MDM source present").
+func SetMobilePolicyFetcher(p PolicyFetcher) {
+	fetcher = p
+}
+
+// loadPlatformPolicy delegates to the native-provided fetcher. Returns
+// (nil, nil) — the platform-absent sentinel — when no fetcher has been
+// registered yet, so the package behaves identically to a desktop
+// device without an MDM source.
+func loadPlatformPolicy() (map[string]any, error) {
+	if fetcher == nil {
+		//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see LoadPolicy.
+		return nil, nil
+	}
+	return fetcher.Fetch(), nil
 }

client/server/mdm_mobile.go

@@ -0,0 +1,20 @@
+//go:build ios || android
+
+package server
+
+// OnMDMPolicyChanged is the mobile entry point invoked by the native
+// layer (Kotlin / Swift) when the OS broadcasts an MDM configuration
+// change (ACTION_APPLICATION_RESTRICTIONS_CHANGED on Android,
+// UserDefaults.didChangeNotification on iOS). The OS notification only
+// signals "something changed" — no payload — so this hook re-runs the
+// same load-and-diff sequence the desktop ticker triggers on each
+// tick. The fresh policy values are read on demand by
+// mdm.loadPlatformPolicy, which on mobile delegates to the
+// PolicyFetcher registered by the native layer via
+// mdm.SetMobilePolicyFetcher.
+//
+// Safe to call at any time after Server construction. Re-entrancy is
+// serialised by the s.mutex acquired inside onMDMPolicyChange.
+func (s *Server) OnMDMPolicyChanged() {
+	s.onMDMPolicyChange(nil, nil)
+}