NatController.cpp revision ac208608c9e10ef199fdd11c38a31675ee9290c0
1/* 2 * Copyright (C) 2008 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 <stdlib.h> 18#include <errno.h> 19#include <sys/socket.h> 20#include <sys/stat.h> 21#include <fcntl.h> 22#include <netinet/in.h> 23#include <arpa/inet.h> 24#include <string.h> 25#include <cutils/properties.h> 26 27#define LOG_TAG "NatController" 28#include <cutils/log.h> 29 30#include "NatController.h" 31 32extern "C" int logwrap(int argc, const char **argv, int background); 33 34static char IPTABLES_PATH[] = "/system/bin/iptables"; 35 36NatController::NatController() { 37 natCount = 0; 38} 39 40NatController::~NatController() { 41} 42 43int NatController::runIptablesCmd(const char *cmd) { 44 char buffer[255]; 45 46 strncpy(buffer, cmd, sizeof(buffer)-1); 47 48 const char *args[16]; 49 char *next = buffer; 50 char *tmp; 51 52 args[0] = IPTABLES_PATH; 53 args[1] = "--verbose"; 54 int i = 2; 55 56 while ((tmp = strsep(&next, " "))) { 57 args[i++] = tmp; 58 if (i == 16) { 59 LOGE("iptables argument overflow"); 60 errno = E2BIG; 61 return -1; 62 } 63 } 64 args[i] = NULL; 65 66 return logwrap(i, args, 0); 67} 68 69int NatController::setDefaults() { 70 71 if (runIptablesCmd("-P INPUT ACCEPT")) 72 return -1; 73 if (runIptablesCmd("-F INPUT")) 74 return -1; 75 if (runIptablesCmd("-P OUTPUT ACCEPT")) 76 return -1; 77 if (runIptablesCmd("-F OUTPUT")) 78 return -1; 79 if (runIptablesCmd("-P FORWARD DROP")) 80 return -1; 81 if (runIptablesCmd("-F FORWARD")) 82 return -1; 83 if (runIptablesCmd("-t nat -F")) 84 return -1; 85 return 0; 86} 87 88bool NatController::interfaceExists(const char *iface) { 89 // XXX: Implement this 90 return true; 91} 92 93int NatController::doNatCommands(const char *intIface, const char *extIface, bool add) { 94 char cmd[255]; 95 96 char bootmode[PROPERTY_VALUE_MAX] = {0}; 97 property_get("ro.bootmode", bootmode, "unknown"); 98 if (0 != strcmp("bp-tools", bootmode)) { 99 // handle decrement to 0 case (do reset to defaults) and erroneous dec below 0 100 if (add == false) { 101 if (natCount <= 1) { 102 int ret = setDefaults(); 103 if (ret == 0) { 104 natCount=0; 105 } 106 return ret; 107 } 108 } 109 } 110 111 if (!interfaceExists(intIface) || !interfaceExists (extIface)) { 112 LOGE("Invalid interface specified"); 113 errno = ENODEV; 114 return -1; 115 } 116 117 snprintf(cmd, sizeof(cmd), 118 "-%s FORWARD -i %s -o %s -m state --state ESTABLISHED,RELATED -j ACCEPT", 119 (add ? "A" : "D"), 120 extIface, intIface); 121 if (runIptablesCmd(cmd)) { 122 return -1; 123 } 124 125 snprintf(cmd, sizeof(cmd), "-%s FORWARD -i %s -o %s -j ACCEPT", (add ? "A" : "D"), 126 intIface, extIface); 127 if (runIptablesCmd(cmd)) { 128 // unwind what's been done, but don't care about success - what more could we do? 129 snprintf(cmd, sizeof(cmd), 130 "-%s FORWARD -i %s -o %s -m state --state ESTABLISHED,RELATED -j ACCEPT", 131 (!add ? "A" : "D"), 132 extIface, intIface); 133 return -1; 134 } 135 136 // add this if we are the first added nat 137 if (add && natCount == 0) { 138 snprintf(cmd, sizeof(cmd), "-t nat -A POSTROUTING -o %s -j MASQUERADE", extIface); 139 if (runIptablesCmd(cmd)) { 140 if (0 != strcmp("bp-tools", bootmode)) { 141 // unwind what's been done, but don't care about success - what more could we do? 142 setDefaults();; 143 } 144 return -1; 145 } 146 } 147 148 if (add) { 149 natCount++; 150 } else { 151 natCount--; 152 } 153 return 0; 154} 155 156int NatController::enableNat(const char *intIface, const char *extIface) { 157 return doNatCommands(intIface, extIface, true); 158} 159 160int NatController::disableNat(const char *intIface, const char *extIface) { 161 return doNatCommands(intIface, extIface, false); 162} 163