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// #define LOG_NDEBUG 0 18 19/* 20 * MODUS OPERANDI 21 * -------------- 22 * 23 * IPTABLES command sequence: 24 * 25 * iptables -F 26 * 27 * iptables -t raw -F idletimer_PREROUTING 28 * iptables -t mangle -F idletimer_POSTROUTING 29 * 30 * 31 * iptables -t raw -N idletimer_PREROUTING 32 * iptables -t mangle -N idletimer_POSTROUTING 33 * 34 * iptables -t raw -D PREROUTING -j idletimer_PREROUTING 35 * iptables -t mangle -D POSTROUTING -j idletimer_POSTROUTING 36 * 37 * 38 * iptables -t raw -I PREROUTING -j idletimer_PREROUTING 39 * iptables -t mangle -I POSTROUTING -j idletimer_POSTROUTING 40 * 41 * # For notifications to work the lable name must match the name of a valid interface. 42 * # If the label name does match an interface, the rules will be a no-op. 43 * 44 * iptables -t raw -A idletimer_PREROUTING -i rmnet0 -j IDLETIMER --timeout 5 --label test-chain --send_nl_msg 1 45 * iptables -t mangle -A idletimer_POSTROUTING -o rmnet0 -j IDLETIMER --timeout 5 --label test-chain --send_nl_msg 1 46 * 47 * iptables -nxvL -t raw 48 * iptables -nxvL -t mangle 49 * 50 * ================= 51 * 52 * ndc command sequence 53 * ------------------ 54 * ndc idletimer enable 55 * ndc idletimer add <iface> <timeout> <class label> 56 * ndc idletimer remove <iface> <timeout> <class label> 57 * 58 * Monitor effect on the iptables chains after each step using: 59 * iptables -nxvL -t raw 60 * iptables -nxvL -t mangle 61 * 62 * Remember that the timeout value has to be same at the time of the 63 * removal. 64 * 65 * ================= 66 * 67 * Verifying the iptables rule 68 * --------------------------- 69 * We want to make sure the iptable rules capture every packet. It can be 70 * verified with tcpdump. First take a note of the pkts count for the two rules: 71 * 72 * adb shell iptables -t mangle -L idletimer_mangle_POSTROUTING -v && adb shell iptables -t raw -L idletimer_raw_PREROUTING -v 73 * 74 * And then, before any network traffics happen on the device, run tcpdump: 75 * 76 * adb shell tcpdump | tee tcpdump.log 77 * 78 * After a while run iptables commands again, you could then count the number 79 * of incoming and outgoing packets captured by tcpdump, and compare that with 80 * the numbers reported by iptables command. There shouldn't be too much 81 * difference on these numbers, i.e., with 2000 packets captured it should 82 * differ by less than 5. 83 * 84 * ================= 85 * 86 * Note that currently if the name of the iface is incorrect, iptables 87 * will setup rules without checking if it is the name of a valid 88 * interface (although no notifications will ever be received). It is 89 * the responsibility of code in Java land to ensure that the interface name 90 * is correct. The benefit of this, is that idletimers can be setup on 91 * interfaces than come and go. 92 * 93 * A remove should be called for each add command issued during cleanup, as duplicate 94 * entries of the rule may exist and will all have to removed. 95 * 96 */ 97 98#include <stdlib.h> 99#include <errno.h> 100#include <sys/socket.h> 101#include <sys/stat.h> 102#include <fcntl.h> 103#include <netinet/in.h> 104#include <arpa/inet.h> 105#include <string.h> 106#include <cutils/properties.h> 107 108#define LOG_TAG "IdletimerController" 109#include <cutils/log.h> 110 111#include "IdletimerController.h" 112#include "NetdConstants.h" 113 114extern "C" int system_nosh(const char *command); 115 116const char* IdletimerController::LOCAL_RAW_PREROUTING = "idletimer_raw_PREROUTING"; 117const char* IdletimerController::LOCAL_MANGLE_POSTROUTING = "idletimer_mangle_POSTROUTING"; 118 119IdletimerController::IdletimerController() { 120} 121 122IdletimerController::~IdletimerController() { 123} 124/* return 0 or non-zero */ 125int IdletimerController::runIpxtablesCmd(const char *cmd) { 126 char *buffer; 127 size_t len = strnlen(cmd, 255); 128 int res; 129 130 if (len == 255) { 131 ALOGE("command too long"); 132 return -1; 133 } 134 135 asprintf(&buffer, "%s %s", IPTABLES_PATH, cmd); 136 res = system_nosh(buffer); 137 ALOGV("%s #%d", buffer, res); 138 free(buffer); 139 140 return res; 141} 142 143bool IdletimerController::setupIptablesHooks() { 144 return true; 145} 146 147int IdletimerController::setDefaults() { 148 int res; 149 char *buffer; 150 asprintf(&buffer, "-t raw -F %s", LOCAL_RAW_PREROUTING); 151 res = runIpxtablesCmd(buffer); 152 free(buffer); 153 154 if (res) 155 return res; 156 157 asprintf(&buffer, "-t mangle -F %s", LOCAL_MANGLE_POSTROUTING); 158 res = runIpxtablesCmd(buffer); 159 free(buffer); 160 return res; 161} 162 163int IdletimerController::enableIdletimerControl() { 164 int res = setDefaults(); 165 return res; 166} 167 168int IdletimerController::disableIdletimerControl() { 169 int res = setDefaults(); 170 return res; 171} 172 173int IdletimerController::modifyInterfaceIdletimer(IptOp op, const char *iface, 174 uint32_t timeout, 175 const char *classLabel) { 176 int res; 177 char *buffer; 178 asprintf(&buffer, "-t raw -%c %s -i %s -j IDLETIMER" 179 " --timeout %u --label %s --send_nl_msg 1", 180 (op == IptOpAdd) ? 'A' : 'D', LOCAL_RAW_PREROUTING, iface, timeout, classLabel); 181 res = runIpxtablesCmd(buffer); 182 free(buffer); 183 184 if (res) 185 return res; 186 187 asprintf(&buffer, "-t mangle -%c %s -o %s -j IDLETIMER" 188 " --timeout %u --label %s --send_nl_msg 1", 189 (op == IptOpAdd) ? 'A' : 'D', LOCAL_MANGLE_POSTROUTING, iface, timeout, classLabel); 190 res = runIpxtablesCmd(buffer); 191 free(buffer); 192 193 return res; 194} 195 196int IdletimerController::addInterfaceIdletimer(const char *iface, 197 uint32_t timeout, 198 const char *classLabel) { 199 return modifyInterfaceIdletimer(IptOpAdd, iface, timeout, classLabel); 200} 201 202int IdletimerController::removeInterfaceIdletimer(const char *iface, 203 uint32_t timeout, 204 const char *classLabel) { 205 return modifyInterfaceIdletimer(IptOpDelete, iface, timeout, classLabel); 206} 207