Add a dummy network that discards all packets.

Bug: 19500693
Change-Id: Ic25f2d8c481f1528e887e43ca3fa868189582110

7 files changed, 124 insertions, 1 deletions

diff --git a/server/Android.mk b/server/Android.mk
index 55aa87cd..9111d84e 100644
--- a/server/Android.mk
+++ b/server/Android.mk
@@ -44,6 +44,7 @@ LOCAL_SRC_FILES := \
         ClatdController.cpp \
         CommandListener.cpp \
         DnsProxyListener.cpp \
+        DummyNetwork.cpp \
         FirewallController.cpp \
         FwmarkServer.cpp \
         IdletimerController.cpp \
diff --git a/server/DummyNetwork.cpp b/server/DummyNetwork.cpp
new file mode 100644
index 00000000..ff2cb412
--- /dev/null
+++ b/server/DummyNetwork.cpp
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "DummyNetwork.h"
+
+#include "RouteController.h"
+
+#define LOG_TAG "Netd"
+#include "log/log.h"
+
+const char* DummyNetwork::INTERFACE_NAME = "dummy0";
+
+DummyNetwork::DummyNetwork(unsigned netId) : Network(netId) {
+    mInterfaces.insert(INTERFACE_NAME);
+}
+
+DummyNetwork::~DummyNetwork() {
+}
+
+Network::Type DummyNetwork::getType() const {
+    return DUMMY;
+}
+
+int DummyNetwork::addInterface(const std::string& /* interface */) {
+    return -EINVAL;
+}
+
+int DummyNetwork::removeInterface(const std::string& /* interface */) {
+    return -EINVAL;
+}
diff --git a/server/DummyNetwork.h b/server/DummyNetwork.h
new file mode 100644
index 00000000..7bc0d3d4
--- /dev/null
+++ b/server/DummyNetwork.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef NETD_SERVER_DUMMY_NETWORK_H
+#define NETD_SERVER_DUMMY_NETWORK_H
+
+#include "Network.h"
+
+class DummyNetwork : public Network {
+public:
+    static const char* INTERFACE_NAME;
+    explicit DummyNetwork(unsigned netId);
+    virtual ~DummyNetwork();
+
+private:
+    Type getType() const override;
+    int addInterface(const std::string& interface) override WARN_UNUSED_RESULT;
+    int removeInterface(const std::string& interface) override WARN_UNUSED_RESULT;
+};
+
+#endif  // NETD_SERVER_DUMMY_NETWORK_H
diff --git a/server/Network.h b/server/Network.h
index 115997ad..3af53d97 100644
--- a/server/Network.h
+++ b/server/Network.h
@@ -26,6 +26,7 @@
 class Network {
 public:
     enum Type {
+        DUMMY,
         LOCAL,
         PHYSICAL,
         VIRTUAL,
diff --git a/server/NetworkController.cpp b/server/NetworkController.cpp
index 20d8e977..76e4a6af 100644
--- a/server/NetworkController.cpp
+++ b/server/NetworkController.cpp
@@ -32,6 +32,7 @@
 
 #include "NetworkController.h"
 
+#include "DummyNetwork.h"
 #include "Fwmark.h"
 #include "LocalNetwork.h"
 #include "PhysicalNetwork.h"
@@ -53,7 +54,8 @@ const unsigned MAX_NET_ID = 65535;
 
 const unsigned NetworkController::MIN_OEM_ID   =  1;
 const unsigned NetworkController::MAX_OEM_ID   = 50;
-// NetIds 51..98 are reserved for future use.
+const unsigned NetworkController::DUMMY_NET_ID = 51;
+// NetIds 52..98 are reserved for future use.
 const unsigned NetworkController::LOCAL_NET_ID = 99;
 
 // All calls to methods here are made while holding a write lock on mRWLock.
@@ -132,6 +134,7 @@ int NetworkController::DelegateImpl::modifyFallthrough(const std::string& physic
 NetworkController::NetworkController() :
         mDelegateImpl(new NetworkController::DelegateImpl(this)), mDefaultNetId(NETID_UNSET) {
     mNetworks[LOCAL_NET_ID] = new LocalNetwork(LOCAL_NET_ID);
+    mNetworks[DUMMY_NET_ID] = new DummyNetwork(DUMMY_NET_ID);
 }
 
 unsigned NetworkController::getDefaultNetwork() const {
diff --git a/server/NetworkController.h b/server/NetworkController.h
index 5596f0c0..073745da 100644
--- a/server/NetworkController.h
+++ b/server/NetworkController.h
@@ -43,6 +43,7 @@ public:
     static const unsigned MIN_OEM_ID;
     static const unsigned MAX_OEM_ID;
     static const unsigned LOCAL_NET_ID;
+    static const unsigned DUMMY_NET_ID;
 
     NetworkController();
 
diff --git a/server/RouteController.cpp b/server/RouteController.cpp
index c3a600d9..a7d823bb 100644
--- a/server/RouteController.cpp
+++ b/server/RouteController.cpp
@@ -18,10 +18,12 @@
 
 #include "Fwmark.h"
 #include "UidRanges.h"
+#include "DummyNetwork.h"
 
 #define LOG_TAG "Netd"
 #include "log/log.h"
 #include "logwrap/logwrap.h"
+#include "netutils/ifc.h"
 #include "resolv_netid.h"
 
 #include <arpa/inet.h>
@@ -644,6 +646,41 @@ WARN_UNUSED_RESULT int addLocalNetworkRules(unsigned localNetId) {
                         fwmark.intValue, mask.intValue);
 }
 
+int configureDummyNetwork() {
+    const char *interface = DummyNetwork::INTERFACE_NAME;
+    uint32_t table = getRouteTableForInterface(interface);
+    if (table == RT_TABLE_UNSPEC) {
+        // getRouteTableForInterface has already looged an error.
+        return -ESRCH;
+    }
+
+    ifc_init();
+    int ret = ifc_up(interface);
+    ifc_close();
+    if (ret) {
+        ALOGE("Can't bring up %s: %s", interface, strerror(errno));
+        return -errno;
+    }
+
+    if ((ret = modifyOutputInterfaceRule(interface, table, PERMISSION_NONE,
+                                         INVALID_UID, INVALID_UID, ACTION_ADD))) {
+        ALOGE("Can't create oif rule for %s: %s", interface, strerror(-ret));
+        return ret;
+    }
+
+    if ((ret = modifyIpRoute(RTM_NEWROUTE, table, interface, "0.0.0.0/0", NULL))) {
+        ALOGE("Can't add IPv4 default route to %s: %s", interface, strerror(-ret));
+        return ret;
+    }
+
+    if ((ret = modifyIpRoute(RTM_NEWROUTE, table, interface, "::/0", NULL))) {
+        ALOGE("Can't add IPv6 default route to %s: %s", interface, strerror(-ret));
+        return ret;
+    }
+
+    return 0;
+}
+
 // Add a new rule to look up the 'main' table, with the same selectors as the "default network"
 // rule, but with a lower priority. We will never create routes in the main table; it should only be
 // used for directly-connected routes implicitly created by the kernel when adding IP addresses.
@@ -889,6 +926,9 @@ int RouteController::Init(unsigned localNetId) {
     if (int ret = addUnreachableRule()) {
         return ret;
     }
+    // Don't complain if we can't add the dummy network, since not all devices support it.
+    configureDummyNetwork();
+
     updateTableNamesFile();
     return 0;
 }