IdletimerController.cpp revision 0031cead820149e2fe3ccb3cc2fe05758a3cb5c2 
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 nat -F idletimer_PREROUTING
28 * iptables -t nat -F idletimer_POSTROUTING
29 *
30 *
31 * iptables -t nat -N idletimer_PREROUTING
32 * iptables -t nat -N idletimer_POSTROUTING
33 *
34 * iptables -t nat -D PREROUTING -j idletimer_PREROUTING
35 * iptables -t nat -D POSTROUTING -j idletimer_POSTROUTING
36 *
37 *
38 * iptables -t nat -I PREROUTING -j idletimer_PREROUTING
39 * iptables -t nat -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 nat -A idletimer_PREROUTING -i rmnet0 -j IDLETIMER  --timeout 5 --label test-chain --send_nl_msg 1
45 * iptables -t nat -A idletimer_POSTROUTING -o rmnet0 -j IDLETIMER  --timeout 5 --label test-chain --send_nl_msg 1
46 *
47 * iptables -nxvL -t nat
48 *
49 * =================
50 *
51 * ndc command sequence
52 * ------------------
53 * ndc idletimer enable
54 * ndc idletimer add <iface> <timeout>
55 * ndc idletimer remove <iface> <timeout>
56 *
57 * Monitor effect on the iptables chains after each step using:
58 *     iptables -nxvL -t nat
59 *
60 * Remember that the timeout value has to be same at the time of the
61 * removal.
62 *
63 * Note that currently if the name of the iface is incorrect, iptables
64 * will setup rules without checking if it is the name of a valid
65 * interface (although no notifications will ever be received).  It is
66 * the responsibility of code in Java land to ensure that the interface name
67 * is correct. The benefit of this, is that idletimers can be setup on
68 * interfaces than come and go.
69 *
70 * A remove should be called for each add command issued during cleanup, as duplicate
71 * entries of the rule may exist and will all have to removed.
72 *
73 */
74
75#include <stdlib.h>
76#include <errno.h>
77#include <sys/socket.h>
78#include <sys/stat.h>
79#include <fcntl.h>
80#include <netinet/in.h>
81#include <arpa/inet.h>
82#include <string.h>
83#include <cutils/properties.h>
84
85#define LOG_TAG "IdletimerController"
86#include <cutils/log.h>
87
88#include "IdletimerController.h"
89#include "NetdConstants.h"
90
91extern "C" int system_nosh(const char *command);
92
93IdletimerController::IdletimerController() {
94}
95
96IdletimerController::~IdletimerController() {
97}
98/* return 0 or non-zero */
99int IdletimerController::runIpxtablesCmd(const char *cmd) {
100    char *buffer;
101    size_t len = strnlen(cmd, 255);
102    int res;
103
104    if (len == 255) {
105        ALOGE("command too long");
106        return -1;
107    }
108
109    asprintf(&buffer, "%s %s", IPTABLES_PATH, cmd);
110    res = system_nosh(buffer);
111    ALOGV("%s #%d", buffer, res);
112    free(buffer);
113
114    return res;
115}
116
117bool IdletimerController::setupIptablesHooks() {
118    runIpxtablesCmd("-t nat -D PREROUTING -j idletimer_nat_PREROUTING");
119    runIpxtablesCmd("-t nat -F idletimer_nat_PREROUTING");
120    runIpxtablesCmd("-t nat -N idletimer_nat_PREROUTING");
121
122    runIpxtablesCmd("-t nat -D POSTROUTING -j idletimer_nat_POSTROUTING");
123    runIpxtablesCmd("-t nat -F idletimer_nat_POSTROUTING");
124    runIpxtablesCmd("-t nat -N idletimer_nat_POSTROUTING");
125
126    if (runIpxtablesCmd("-t nat -I PREROUTING -j idletimer_nat_PREROUTING")
127        || runIpxtablesCmd("-t nat -I POSTROUTING -j idletimer_nat_POSTROUTING")) {
128        return false;
129    }
130    return true;
131}
132
133int IdletimerController::setDefaults() {
134  if (runIpxtablesCmd("-t nat -F idletimer_nat_PREROUTING")
135      || runIpxtablesCmd("-t nat -F idletimer_nat_POSTROUTING") )
136      return -1;
137  return 0;
138}
139
140int IdletimerController::enableIdletimerControl() {
141    int res = setDefaults();
142    return res;
143}
144
145int IdletimerController::disableIdletimerControl() {
146    int res = setDefaults();
147    return res;
148}
149
150int IdletimerController::modifyInterfaceIdletimer(IptOp op, const char *iface,
151                                                  uint32_t timeout) {
152  int res;
153  char *buffer;
154  asprintf(&buffer, "-t nat -%c idletimer_nat_PREROUTING -i %s -j IDLETIMER"
155           " --timeout %u --label %s --send_nl_msg 1",
156           (op == IptOpAdd) ? 'A' : 'D', iface, timeout, iface);
157  res = runIpxtablesCmd(buffer);
158  free(buffer);
159
160  asprintf(&buffer, "-t nat -%c idletimer_nat_POSTROUTING -o %s -j IDLETIMER"
161           " --timeout %u --label %s --send_nl_msg 1",
162           (op == IptOpAdd) ? 'A' : 'D', iface, timeout, iface);
163  res |= runIpxtablesCmd(buffer);
164  free(buffer);
165
166  return res;
167}
168
169int IdletimerController::addInterfaceIdletimer(const char *iface, uint32_t timeout) {
170  return modifyInterfaceIdletimer(IptOpAdd, iface, timeout);
171}
172
173int IdletimerController::removeInterfaceIdletimer(const char *iface, uint32_t timeout) {
174  return modifyInterfaceIdletimer(IptOpDelete, iface, timeout);
175}
176