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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <stdio.h>
     18 #include <stdlib.h>
     19 #include <sys/types.h>
     20 #include <sys/wait.h>
     21 #include <errno.h>
     22 #include <string.h>
     23 #include <unistd.h>
     24 
     25 #define LOG_TAG "OemIptablesHook"
     26 #include <cutils/log.h>
     27 #include "NetdConstants.h"
     28 
     29 extern "C" int system_nosh(const char *command);
     30 
     31 
     32 static int runIptablesCmd(const char *cmd) {
     33     char *buffer;
     34     size_t len = strnlen(cmd, 255);
     35     int res;
     36 
     37     if (len == 255) {
     38         ALOGE("command too long");
     39         return -1;
     40     }
     41 
     42     asprintf(&buffer, "%s %s", IPTABLES_PATH, cmd);
     43     res = system_nosh(buffer);
     44     free(buffer);
     45     return res;
     46 }
     47 
     48 static bool oemCleanupHooks() {
     49     runIptablesCmd("-F oem_out");
     50     runIptablesCmd("-F oem_fwd");
     51     runIptablesCmd("-t nat -F oem_nat_pre");
     52     return true;
     53 }
     54 
     55 static bool oemInitChains() {
     56     int ret = system(OEM_SCRIPT_PATH);
     57     if ((-1 == ret) || (0 != WEXITSTATUS(ret))) {
     58         ALOGE("%s failed: %s", OEM_SCRIPT_PATH, strerror(errno));
     59         oemCleanupHooks();
     60         return false;
     61     }
     62     return true;
     63 }
     64 
     65 
     66 void setupOemIptablesHook() {
     67     if (0 == access(OEM_SCRIPT_PATH, R_OK | X_OK)) {
     68         // The call to oemCleanupHooks() is superfluous when done on bootup,
     69         // but is needed for the case where netd has crashed/stopped and is
     70         // restarted.
     71         if (oemCleanupHooks() && oemInitChains()) {
     72             ALOGI("OEM iptable hook installed.");
     73         }
     74     }
     75 }
     76