netd: Add primitive NAT control

Update: Add stub function to validate interface existance

Signed-off-by: San Mehat <san@google.com>

5 files changed, 174 insertions, 10 deletions

diff --git a/Android.mk b/Android.mk
index e4a640cb..910c819c 100644
--- a/Android.mk
+++ b/Android.mk
@@ -16,7 +16,8 @@ LOCAL_SRC_FILES:=                                      \
                   NetlinkManager.cpp                   \
                   NetlinkHandler.cpp                   \
                   logwrapper.c                         \
-                  TetherController.cpp
+                  TetherController.cpp                 \
+                  NatController.cpp
 
 LOCAL_MODULE:= netd
 
diff --git a/CommandListener.cpp b/CommandListener.cpp
index 56f55fbd..4bfb356a 100644
--- a/CommandListener.cpp
+++ b/CommandListener.cpp
@@ -31,6 +31,7 @@
 #include "ResponseCode.h"
 
 TetherController *CommandListener::sTetherCtrl = NULL;
+NatController *CommandListener::sNatCtrl = NULL;
 
 CommandListener::CommandListener() :
                  FrameworkListener("netd") {
@@ -41,6 +42,8 @@ CommandListener::CommandListener() :
 
     if (!sTetherCtrl)
         sTetherCtrl = new TetherController();
+    if (!sNatCtrl)
+        sNatCtrl = new NatController();
 }
 
 CommandListener::ListInterfacesCmd::ListInterfacesCmd() :
@@ -196,15 +199,10 @@ int CommandListener::NatCmd::runCommand(SocketClient *cli,
         return 0;
     }
 
-    if (!strcmp(argv[1], "binding")) {
-        if (!strcmp(argv[2], "add")) {
-            rc = 0;
-        } else if (!strcmp(argv[2], "remove")) {
-            rc = 0;
-        } else {
-            cli->sendMsg(ResponseCode::CommandSyntaxError, "Unknown nat binding cmd", false);
-            return 0;
-        }
+    if (!strcmp(argv[1], "enable")) {
+        rc = sNatCtrl->enableNat(argv[2], argv[3]);
+    } else if (!strcmp(argv[1], "disable")) {
+        rc = sNatCtrl->disableNat(argv[2], argv[3]);
     } else {
         cli->sendMsg(ResponseCode::CommandSyntaxError, "Unknown nat cmd", false);
         return 0;
diff --git a/CommandListener.h b/CommandListener.h
index 1ec65ae6..3d69ebad 100644
--- a/CommandListener.h
+++ b/CommandListener.h
@@ -18,11 +18,14 @@
 #define _COMMANDLISTENER_H__
 
 #include <sysutils/FrameworkListener.h>
+
 #include "NetdCommand.h"
 #include "TetherController.h"
+#include "NatController.h"
 
 class CommandListener : public FrameworkListener {
     static TetherController *sTetherCtrl;
+    static NatController *sNatCtrl;
 
 public:
     CommandListener();
diff --git a/NatController.cpp b/NatController.cpp
new file mode 100644
index 00000000..3539844f
--- /dev/null
+++ b/NatController.cpp
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2008 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 <stdlib.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#define LOG_TAG "NatController"
+#include <cutils/log.h>
+
+#include "NatController.h"
+
+extern "C" int logwrap(int argc, const char **argv, int background);
+
+static char IPTABLES_PATH[] = "/system/bin/iptables";
+
+NatController::NatController() {
+}
+
+NatController::~NatController() {
+}
+
+int NatController::runIptablesCmd(const char *cmd) {
+    char buffer[255];
+
+    strncpy(buffer, cmd, sizeof(buffer)-1);
+
+    const char *args[16];
+    char *next = buffer;
+    char *tmp;
+
+    args[0] = IPTABLES_PATH;
+    args[1] = "--verbose";
+    int i = 2;
+
+    while ((tmp = strsep(&next, " "))) {
+        args[i++] = tmp;
+        if (i == 16) {
+            LOGE("iptables argument overflow");
+            errno = E2BIG;
+            return -1;
+        }
+    }
+    args[i] = NULL;
+
+    return logwrap(i, args, 0);
+}
+
+int NatController::setDefaults() {
+
+    if (runIptablesCmd("-P INPUT ACCEPT"))
+        return -1;
+    if (runIptablesCmd("-F INPUT"))
+        return -1;
+    if (runIptablesCmd("-P OUTPUT ACCEPT"))
+        return -1;
+    if (runIptablesCmd("-F OUTPUT"))
+        return -1;
+    if (runIptablesCmd("-P FORWARD DROP"))
+        return -1;
+    if (runIptablesCmd("-F FORWARD"))
+        return -1;
+    if (runIptablesCmd("-t nat -F"))
+        return -1;
+    return 0;
+}
+
+bool NatController::interfaceExists(const char *iface) {
+    // XXX: STOPSHIP - Implement this
+    return true;
+}
+
+// TODO: Make this work for multiple masqueraded networks
+int NatController::enableNat(const char *intIface, const char *extIface) {
+    char cmd[255];
+
+    if (!interfaceExists(intIface) || !interfaceExists (extIface)) {
+        LOGE("Invalid interface specified");
+        errno = ENODEV;
+        return -1;
+    }
+
+    snprintf(cmd, sizeof(cmd),
+             "-A FORWARD -i %s -o %s -m state --state ESTABLISHED,RELATED -j ACCEPT",
+             extIface, intIface);
+    if (runIptablesCmd(cmd)) {
+        return -1;
+    }
+
+    snprintf(cmd, sizeof(cmd), "-A FORWARD -i %s -o %s -j ACCEPT", intIface, extIface);
+    if (runIptablesCmd(cmd)) {
+        return -1;
+    }
+
+    snprintf(cmd, sizeof(cmd), "-t nat -A POSTROUTING -o %s -j MASQUERADE", extIface);
+    if (runIptablesCmd(cmd)) {
+        return -1;
+    }
+
+    return 0;
+}
+
+// TODO: Make this work for multiple masqueraded networks
+int NatController::disableNat(const char *intIface, const char *extIface) {
+    return setDefaults();
+}
diff --git a/NatController.h b/NatController.h
new file mode 100644
index 00000000..4182f1d1
--- /dev/null
+++ b/NatController.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2008 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 _NAT_CONTROLLER_H
+#define _NAT_CONTROLLER_H
+
+#include <linux/in.h>
+
+#include <utils/List.h>
+
+class NatController {
+
+public:
+    NatController();
+    virtual ~NatController();
+
+    int enableNat(const char *intIface, const char *extIface);
+    int disableNat(const char *intIface, const char *extIface);
+
+private:
+    int setDefaults();
+    int runIptablesCmd(const char *cmd);
+    bool interfaceExists(const char *iface);
+};
+
+#endif