LineageOS/android_packages_modules_Connectivity
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Carefully select which DNS servers to send to netd

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Select only DNS servers that:
    - are reachable, according to routes in the LinkProperties, AND

    - have a "suitable" source address in the LinkProperites, meaning:
        - IPv4 DNS server:
            - only if LinkProperties has any IPv4 address
        - IPv6 link-local DNS server:
            - only if the server has a scopeId set
            - assume for now that LinkProperties has a suitable
              link-local address
        - IPv6 non-link-local DNS server:
            - only if LinkProperties has a global, preferred IPv6 address

Bug: 19470192
Bug: 20733156
Change-Id: Ibd95f3f7b33a4fb6c36d1cea4adb63c99068f657
This commit is contained in:
Erik Kline
2015-06-17 13:19:54 +09:00
parent 7fb7a4b0f1
commit 04270063ed
1 changed files with 45 additions and 1 deletions
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46
services/core/java/com/android/server/ConnectivityService.java
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@@ -136,11 +136,13 @@ import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
@@ -3920,10 +3922,52 @@ public class ConnectivityService extends IConnectivityManager.Stub
}
return !routeDiff.added.isEmpty() || !routeDiff.removed.isEmpty();
}
// TODO: investigate moving this into LinkProperties, if only to make more accurate
// the isProvisioned() checks.
private static Collection<InetAddress> getLikelyReachableDnsServers(LinkProperties lp) {
final ArrayList<InetAddress> dnsServers = new ArrayList<InetAddress>();
final List<RouteInfo> allRoutes = lp.getAllRoutes();
for (InetAddress nameserver : lp.getDnsServers()) {
// If the LinkProperties doesn't include a route to the nameserver, ignore it.
final RouteInfo bestRoute = RouteInfo.selectBestRoute(allRoutes, nameserver);
if (bestRoute == null) {
continue;
}
// TODO: better source address evaluation for destination addresses.
if (nameserver instanceof Inet4Address) {
if (!lp.hasIPv4Address()) {
continue;
}
} else if (nameserver instanceof Inet6Address) {
if (nameserver.isLinkLocalAddress()) {
if (((Inet6Address)nameserver).getScopeId() == 0) {
// For now, just make sure link-local DNS servers have
// scopedIds set, since DNS lookups will fail otherwise.
// TODO: verify the scopeId matches that of lp's interface.
continue;
}
} else {
if (bestRoute.isIPv6Default() && !lp.hasGlobalIPv6Address()) {
// TODO: reconsider all corner cases (disconnected ULA networks, ...).
continue;
}
}
}
dnsServers.add(nameserver);
}
return Collections.unmodifiableList(dnsServers);
}
private void updateDnses(LinkProperties newLp, LinkProperties oldLp, int netId,
boolean flush, boolean useDefaultDns) {
// TODO: consider comparing the getLikelyReachableDnsServers() lists, in case the
// route to a DNS server has been removed (only really applicable in special cases
// where there is no default route).
if (oldLp == null || (newLp.isIdenticalDnses(oldLp) == false)) {
Collection<InetAddress> dnses = newLp.getDnsServers();
Collection<InetAddress> dnses = getLikelyReachableDnsServers(newLp);
if (dnses.size() == 0 && mDefaultDns != null && useDefaultDns) {
dnses = new ArrayList();
dnses.add(mDefaultDns);