Fix service resolve on tethering downstreams
Tethering downstreams do not have NetworkAgents, and although they have
a netid of 99, Networks with netId 99 are not usable by apps for most
connectivity APIs.
Recent refactoring in NsdService adds the Network of a found service
into its NsdServiceInfo, and uses that network to resolve the service.
In that case the Network has netId 99 and resolving the service fails.
Avoid that problem by:
- Keeping the Network field null when a service is found on a tethering
downstream; this avoids giving apps a confusing and unusable Network
with netId 99
- Using the interface index found during discovery to resolve the
service, if the app uses the NsdServiceInfo that was obtained from
discovery to resolve. If not, all interfaces will be used to resolve,
as per legacy APIs.
Bug: 233979892
Test: atest NsdServiceTest
Also manual test with 2 devices connected via hotspot
Change-Id: Idd176153b67ccbd1d4f1b1fd66dafaa2f3a9e27a
diff --git a/service-t/src/com/android/server/NsdService.java b/service-t/src/com/android/server/NsdService.java
index 6def44f..95e6114 100644
--- a/service-t/src/com/android/server/NsdService.java
+++ b/service-t/src/com/android/server/NsdService.java
@@ -23,6 +23,7 @@
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.ConnectivityManager;
+import android.net.INetd;
import android.net.LinkProperties;
import android.net.Network;
import android.net.mdns.aidl.DiscoveryInfo;
@@ -466,7 +467,7 @@
// interfaces that do not have an associated Network.
break;
}
- servInfo.setNetwork(new Network(foundNetId));
+ setServiceNetworkForCallback(servInfo, info.netId, info.interfaceIdx);
clientInfo.onServiceFound(clientId, servInfo);
break;
}
@@ -476,10 +477,11 @@
final String type = info.registrationType;
final int lostNetId = info.netId;
servInfo = new NsdServiceInfo(name, type);
- // The network could be null if it was torn down when the service is lost
- // TODO: avoid returning null in that case, possibly by remembering found
- // services on the same interface index and their network at the time
- servInfo.setNetwork(lostNetId == 0 ? null : new Network(lostNetId));
+ // The network could be set to null (netId 0) if it was torn down when the
+ // service is lost
+ // TODO: avoid returning null in that case, possibly by remembering
+ // found services on the same interface index and their network at the time
+ setServiceNetworkForCallback(servInfo, lostNetId, info.interfaceIdx);
clientInfo.onServiceLost(clientId, servInfo);
break;
}
@@ -557,7 +559,6 @@
final GetAddressInfo info = (GetAddressInfo) obj;
final String address = info.address;
final int netId = info.netId;
- final Network network = netId == NETID_UNSET ? null : new Network(netId);
InetAddress serviceHost = null;
try {
serviceHost = InetAddress.getByName(address);
@@ -568,9 +569,10 @@
// If the resolved service is on an interface without a network, consider it
// as a failure: it would not be usable by apps as they would need
// privileged permissions.
- if (network != null && serviceHost != null) {
+ if (netId != NETID_UNSET && serviceHost != null) {
clientInfo.mResolvedService.setHost(serviceHost);
- clientInfo.mResolvedService.setNetwork(network);
+ setServiceNetworkForCallback(clientInfo.mResolvedService,
+ netId, info.interfaceIdx);
clientInfo.onResolveServiceSucceeded(
clientId, clientInfo.mResolvedService);
} else {
@@ -590,6 +592,26 @@
}
}
+ private static void setServiceNetworkForCallback(NsdServiceInfo info, int netId, int ifaceIdx) {
+ switch (netId) {
+ case NETID_UNSET:
+ info.setNetwork(null);
+ break;
+ case INetd.LOCAL_NET_ID:
+ // Special case for LOCAL_NET_ID: Networks on netId 99 are not generally
+ // visible / usable for apps, so do not return it. Store the interface
+ // index instead, so at least if the client tries to resolve the service
+ // with that NsdServiceInfo, it will be done on the same interface.
+ // If they recreate the NsdServiceInfo themselves, resolution would be
+ // done on all interfaces as before T, which should also work.
+ info.setNetwork(null);
+ info.setInterfaceIndex(ifaceIdx);
+ break;
+ default:
+ info.setNetwork(new Network(netId));
+ }
+ }
+
// The full service name is escaped from standard DNS rules on mdnsresponder, making it suitable
// for passing to standard system DNS APIs such as res_query() . Thus, make the service name
// unescape for getting right service address. See "Notes on DNS Name Escaping" on
@@ -767,9 +789,8 @@
String type = service.getServiceType();
int port = service.getPort();
byte[] textRecord = service.getTxtRecord();
- final Network network = service.getNetwork();
- final int registerInterface = getNetworkInterfaceIndex(network);
- if (network != null && registerInterface == IFACE_IDX_ANY) {
+ final int registerInterface = getNetworkInterfaceIndex(service);
+ if (service.getNetwork() != null && registerInterface == IFACE_IDX_ANY) {
Log.e(TAG, "Interface to register service on not found");
return false;
}
@@ -781,10 +802,9 @@
}
private boolean discoverServices(int discoveryId, NsdServiceInfo serviceInfo) {
- final Network network = serviceInfo.getNetwork();
final String type = serviceInfo.getServiceType();
- final int discoverInterface = getNetworkInterfaceIndex(network);
- if (network != null && discoverInterface == IFACE_IDX_ANY) {
+ final int discoverInterface = getNetworkInterfaceIndex(serviceInfo);
+ if (serviceInfo.getNetwork() != null && discoverInterface == IFACE_IDX_ANY) {
Log.e(TAG, "Interface to discover service on not found");
return false;
}
@@ -798,9 +818,8 @@
private boolean resolveService(int resolveId, NsdServiceInfo service) {
final String name = service.getServiceName();
final String type = service.getServiceType();
- final Network network = service.getNetwork();
- final int resolveInterface = getNetworkInterfaceIndex(network);
- if (network != null && resolveInterface == IFACE_IDX_ANY) {
+ final int resolveInterface = getNetworkInterfaceIndex(service);
+ if (service.getNetwork() != null && resolveInterface == IFACE_IDX_ANY) {
Log.e(TAG, "Interface to resolve service on not found");
return false;
}
@@ -816,8 +835,17 @@
* this is to support the legacy mdnsresponder implementation, which historically resolved
* services on an unspecified network.
*/
- private int getNetworkInterfaceIndex(Network network) {
- if (network == null) return IFACE_IDX_ANY;
+ private int getNetworkInterfaceIndex(NsdServiceInfo serviceInfo) {
+ final Network network = serviceInfo.getNetwork();
+ if (network == null) {
+ // Fallback to getInterfaceIndex if present (typically if the NsdServiceInfo was
+ // provided by NsdService from discovery results, and the service was found on an
+ // interface that has no app-usable Network).
+ if (serviceInfo.getInterfaceIndex() != 0) {
+ return serviceInfo.getInterfaceIndex();
+ }
+ return IFACE_IDX_ANY;
+ }
final ConnectivityManager cm = mContext.getSystemService(ConnectivityManager.class);
if (cm == null) {