netd: Add primitive NAT control
Update: Add stub function to validate interface existance
Signed-off-by: San Mehat <san@google.com>
diff --git a/NatController.cpp b/NatController.cpp
new file mode 100644
index 0000000..3539844
--- /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();
+}