TetherController.cpp revision f4cfad361175a7f9ccf4d41e76a9b289c3c3da22 
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 <fcntl.h>
20#include <string.h>
21
22#include <sys/socket.h>
23#include <sys/stat.h>
24#include <sys/types.h>
25#include <sys/wait.h>
26
27#include <netinet/in.h>
28#include <arpa/inet.h>
29
30#define LOG_TAG "TetherController"
31#include <cutils/log.h>
32#include <cutils/properties.h>
33
34#include "TetherController.h"
35
36TetherController::TetherController() {
37    mInterfaces = new InterfaceCollection();
38    mDnsForwarders = new NetAddressCollection();
39    mDaemonFd = -1;
40    mDaemonPid = 0;
41}
42
43TetherController::~TetherController() {
44    InterfaceCollection::iterator it;
45
46    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
47        free(*it);
48    }
49    mInterfaces->clear();
50
51    mDnsForwarders->clear();
52}
53
54int TetherController::setIpFwdEnabled(bool enable) {
55
56    ALOGD("Setting IP forward enable = %d", enable);
57
58    // In BP tools mode, do not disable IP forwarding
59    char bootmode[PROPERTY_VALUE_MAX] = {0};
60    property_get("ro.bootmode", bootmode, "unknown");
61    if ((enable == false) && (0 == strcmp("bp-tools", bootmode))) {
62        return 0;
63    }
64
65    int fd = open("/proc/sys/net/ipv4/ip_forward", O_WRONLY);
66    if (fd < 0) {
67        ALOGE("Failed to open ip_forward (%s)", strerror(errno));
68        return -1;
69    }
70
71    if (write(fd, (enable ? "1" : "0"), 1) != 1) {
72        ALOGE("Failed to write ip_forward (%s)", strerror(errno));
73        close(fd);
74        return -1;
75    }
76    close(fd);
77    return 0;
78}
79
80bool TetherController::getIpFwdEnabled() {
81    int fd = open("/proc/sys/net/ipv4/ip_forward", O_RDONLY);
82
83    if (fd < 0) {
84        ALOGE("Failed to open ip_forward (%s)", strerror(errno));
85        return false;
86    }
87
88    char enabled;
89    if (read(fd, &enabled, 1) != 1) {
90        ALOGE("Failed to read ip_forward (%s)", strerror(errno));
91        close(fd);
92        return -1;
93    }
94
95    close(fd);
96    return (enabled  == '1' ? true : false);
97}
98
99#define TETHER_START_CONST_ARG        8
100
101int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
102    if (mDaemonPid != 0) {
103        ALOGE("Tethering already started");
104        errno = EBUSY;
105        return -1;
106    }
107
108    ALOGD("Starting tethering services");
109
110    pid_t pid;
111    int pipefd[2];
112
113    if (pipe(pipefd) < 0) {
114        ALOGE("pipe failed (%s)", strerror(errno));
115        return -1;
116    }
117
118    /*
119     * TODO: Create a monitoring thread to handle and restart
120     * the daemon if it exits prematurely
121     */
122    if ((pid = fork()) < 0) {
123        ALOGE("fork failed (%s)", strerror(errno));
124        close(pipefd[0]);
125        close(pipefd[1]);
126        return -1;
127    }
128
129    if (!pid) {
130        close(pipefd[1]);
131        if (pipefd[0] != STDIN_FILENO) {
132            if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
133                ALOGE("dup2 failed (%s)", strerror(errno));
134                return -1;
135            }
136            close(pipefd[0]);
137        }
138
139        int num_processed_args = TETHER_START_CONST_ARG + (num_addrs/2) + 1;
140        char **args = (char **)malloc(sizeof(char *) * num_processed_args);
141        args[num_processed_args - 1] = NULL;
142        args[0] = (char *)"/system/bin/dnsmasq";
143        args[1] = (char *)"--keep-in-foreground";
144        args[2] = (char *)"--no-resolv";
145        args[3] = (char *)"--no-poll";
146        args[4] = (char *)"--dhcp-authoritative";
147        // TODO: pipe through metered status from ConnService
148        args[5] = (char *)"--dhcp-option-force=43,ANDROID_METERED";
149        args[6] = (char *)"--pid-file";
150        args[7] = (char *)"";
151
152        int nextArg = TETHER_START_CONST_ARG;
153        for (int addrIndex=0; addrIndex < num_addrs;) {
154            char *start = strdup(inet_ntoa(addrs[addrIndex++]));
155            char *end = strdup(inet_ntoa(addrs[addrIndex++]));
156            asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
157        }
158
159        if (execv(args[0], args)) {
160            ALOGE("execl failed (%s)", strerror(errno));
161        }
162        ALOGE("Should never get here!");
163        _exit(-1);
164    } else {
165        close(pipefd[0]);
166        mDaemonPid = pid;
167        mDaemonFd = pipefd[1];
168        applyDnsInterfaces();
169        ALOGD("Tethering services running");
170    }
171
172    return 0;
173}
174
175int TetherController::stopTethering() {
176
177    if (mDaemonPid == 0) {
178        ALOGE("Tethering already stopped");
179        return 0;
180    }
181
182    ALOGD("Stopping tethering services");
183
184    kill(mDaemonPid, SIGTERM);
185    waitpid(mDaemonPid, NULL, 0);
186    mDaemonPid = 0;
187    close(mDaemonFd);
188    mDaemonFd = -1;
189    ALOGD("Tethering services stopped");
190    return 0;
191}
192
193bool TetherController::isTetheringStarted() {
194    return (mDaemonPid == 0 ? false : true);
195}
196
197#define MAX_CMD_SIZE 1024
198
199int TetherController::setDnsForwarders(char **servers, int numServers) {
200    int i;
201    char daemonCmd[MAX_CMD_SIZE];
202
203    strcpy(daemonCmd, "update_dns");
204    int cmdLen = strlen(daemonCmd);
205
206    mDnsForwarders->clear();
207    for (i = 0; i < numServers; i++) {
208        ALOGD("setDnsForwarders(%d = '%s')", i, servers[i]);
209
210        struct in_addr a;
211
212        if (!inet_aton(servers[i], &a)) {
213            ALOGE("Failed to parse DNS server '%s'", servers[i]);
214            mDnsForwarders->clear();
215            return -1;
216        }
217
218        cmdLen += (strlen(servers[i]) + 1);
219        if (cmdLen + 1 >= MAX_CMD_SIZE) {
220            ALOGD("Too many DNS servers listed");
221            break;
222        }
223
224        strcat(daemonCmd, ":");
225        strcat(daemonCmd, servers[i]);
226        mDnsForwarders->push_back(a);
227    }
228
229    if (mDaemonFd != -1) {
230        ALOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
231        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
232            ALOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
233            mDnsForwarders->clear();
234            return -1;
235        }
236    }
237    return 0;
238}
239
240NetAddressCollection *TetherController::getDnsForwarders() {
241    return mDnsForwarders;
242}
243
244int TetherController::applyDnsInterfaces() {
245    int i;
246    char daemonCmd[MAX_CMD_SIZE];
247
248    strcpy(daemonCmd, "update_ifaces");
249    int cmdLen = strlen(daemonCmd);
250    InterfaceCollection::iterator it;
251    bool haveInterfaces = false;
252
253    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
254        cmdLen += (strlen(*it) + 1);
255        if (cmdLen + 1 >= MAX_CMD_SIZE) {
256            ALOGD("Too many DNS ifaces listed");
257            break;
258        }
259
260        strcat(daemonCmd, ":");
261        strcat(daemonCmd, *it);
262        haveInterfaces = true;
263    }
264
265    if ((mDaemonFd != -1) && haveInterfaces) {
266        ALOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
267        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
268            ALOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
269            return -1;
270        }
271    }
272    return 0;
273}
274
275int TetherController::tetherInterface(const char *interface) {
276    ALOGD("tetherInterface(%s)", interface);
277    mInterfaces->push_back(strdup(interface));
278
279    if (applyDnsInterfaces()) {
280        InterfaceCollection::iterator it;
281        for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
282            if (!strcmp(interface, *it)) {
283                free(*it);
284                mInterfaces->erase(it);
285                break;
286            }
287        }
288        return -1;
289    } else {
290        return 0;
291    }
292}
293
294int TetherController::untetherInterface(const char *interface) {
295    InterfaceCollection::iterator it;
296
297    ALOGD("untetherInterface(%s)", interface);
298
299    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
300        if (!strcmp(interface, *it)) {
301            free(*it);
302            mInterfaces->erase(it);
303
304            return applyDnsInterfaces();
305        }
306    }
307    errno = ENOENT;
308    return -1;
309}
310
311InterfaceCollection *TetherController::getTetheredInterfaceList() {
312    return mInterfaces;
313}
314