TetherController.cpp revision 69261cb65186e27dfbdc1e3eec796437f9968ff9 
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 "NetdConstants.h"
35#include "TetherController.h"
36
37TetherController::TetherController() {
38    mInterfaces = new InterfaceCollection();
39    mDnsForwarders = new NetAddressCollection();
40    mDaemonFd = -1;
41    mDaemonPid = 0;
42}
43
44TetherController::~TetherController() {
45    InterfaceCollection::iterator it;
46
47    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
48        free(*it);
49    }
50    mInterfaces->clear();
51
52    mDnsForwarders->clear();
53}
54
55int TetherController::setIpFwdEnabled(bool enable) {
56
57    ALOGD("Setting IP forward enable = %d", enable);
58
59    // In BP tools mode, do not disable IP forwarding
60    char bootmode[PROPERTY_VALUE_MAX] = {0};
61    property_get("ro.bootmode", bootmode, "unknown");
62    if ((enable == false) && (0 == strcmp("bp-tools", bootmode))) {
63        return 0;
64    }
65
66    int fd = open("/proc/sys/net/ipv4/ip_forward", O_WRONLY);
67    if (fd < 0) {
68        ALOGE("Failed to open ip_forward (%s)", strerror(errno));
69        return -1;
70    }
71
72    if (write(fd, (enable ? "1" : "0"), 1) != 1) {
73        ALOGE("Failed to write ip_forward (%s)", strerror(errno));
74        close(fd);
75        return -1;
76    }
77    close(fd);
78    return 0;
79}
80
81bool TetherController::getIpFwdEnabled() {
82    int fd = open("/proc/sys/net/ipv4/ip_forward", O_RDONLY);
83
84    if (fd < 0) {
85        ALOGE("Failed to open ip_forward (%s)", strerror(errno));
86        return false;
87    }
88
89    char enabled;
90    if (read(fd, &enabled, 1) != 1) {
91        ALOGE("Failed to read ip_forward (%s)", strerror(errno));
92        close(fd);
93        return -1;
94    }
95
96    close(fd);
97    return (enabled  == '1' ? true : false);
98}
99
100#define TETHER_START_CONST_ARG        8
101
102int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
103    if (mDaemonPid != 0) {
104        ALOGE("Tethering already started");
105        errno = EBUSY;
106        return -1;
107    }
108
109    ALOGD("Starting tethering services");
110
111    pid_t pid;
112    int pipefd[2];
113
114    if (pipe(pipefd) < 0) {
115        ALOGE("pipe failed (%s)", strerror(errno));
116        return -1;
117    }
118
119    /*
120     * TODO: Create a monitoring thread to handle and restart
121     * the daemon if it exits prematurely
122     */
123    if ((pid = fork()) < 0) {
124        ALOGE("fork failed (%s)", strerror(errno));
125        close(pipefd[0]);
126        close(pipefd[1]);
127        return -1;
128    }
129
130    if (!pid) {
131        close(pipefd[1]);
132        if (pipefd[0] != STDIN_FILENO) {
133            if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
134                ALOGE("dup2 failed (%s)", strerror(errno));
135                return -1;
136            }
137            close(pipefd[0]);
138        }
139
140        int num_processed_args = TETHER_START_CONST_ARG + (num_addrs/2) + 1;
141        char **args = (char **)malloc(sizeof(char *) * num_processed_args);
142        args[num_processed_args - 1] = NULL;
143        args[0] = (char *)"/system/bin/dnsmasq";
144        args[1] = (char *)"--keep-in-foreground";
145        args[2] = (char *)"--no-resolv";
146        args[3] = (char *)"--no-poll";
147        args[4] = (char *)"--dhcp-authoritative";
148        // TODO: pipe through metered status from ConnService
149        args[5] = (char *)"--dhcp-option-force=43,ANDROID_METERED";
150        args[6] = (char *)"--pid-file";
151        args[7] = (char *)"";
152
153        int nextArg = TETHER_START_CONST_ARG;
154        for (int addrIndex=0; addrIndex < num_addrs;) {
155            char *start = strdup(inet_ntoa(addrs[addrIndex++]));
156            char *end = strdup(inet_ntoa(addrs[addrIndex++]));
157            asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
158        }
159
160        if (execv(args[0], args)) {
161            ALOGE("execl failed (%s)", strerror(errno));
162        }
163        ALOGE("Should never get here!");
164        _exit(-1);
165    } else {
166        close(pipefd[0]);
167        mDaemonPid = pid;
168        mDaemonFd = pipefd[1];
169        applyDnsInterfaces();
170        ALOGD("Tethering services running");
171    }
172
173    return 0;
174}
175
176int TetherController::stopTethering() {
177
178    if (mDaemonPid == 0) {
179        ALOGE("Tethering already stopped");
180        return 0;
181    }
182
183    ALOGD("Stopping tethering services");
184
185    kill(mDaemonPid, SIGTERM);
186    waitpid(mDaemonPid, NULL, 0);
187    mDaemonPid = 0;
188    close(mDaemonFd);
189    mDaemonFd = -1;
190    ALOGD("Tethering services stopped");
191    return 0;
192}
193
194bool TetherController::isTetheringStarted() {
195    return (mDaemonPid == 0 ? false : true);
196}
197
198#define MAX_CMD_SIZE 1024
199
200int TetherController::setDnsForwarders(char **servers, int numServers) {
201    int i;
202    char daemonCmd[MAX_CMD_SIZE];
203
204    strcpy(daemonCmd, "update_dns");
205    int cmdLen = strlen(daemonCmd);
206
207    mDnsForwarders->clear();
208    for (i = 0; i < numServers; i++) {
209        ALOGD("setDnsForwarders(%d = '%s')", i, servers[i]);
210
211        struct in_addr a;
212
213        if (!inet_aton(servers[i], &a)) {
214            ALOGE("Failed to parse DNS server '%s'", servers[i]);
215            mDnsForwarders->clear();
216            return -1;
217        }
218
219        cmdLen += (strlen(servers[i]) + 1);
220        if (cmdLen + 1 >= MAX_CMD_SIZE) {
221            ALOGD("Too many DNS servers listed");
222            break;
223        }
224
225        strcat(daemonCmd, ":");
226        strcat(daemonCmd, servers[i]);
227        mDnsForwarders->push_back(a);
228    }
229
230    if (mDaemonFd != -1) {
231        ALOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
232        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
233            ALOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
234            mDnsForwarders->clear();
235            return -1;
236        }
237    }
238    return 0;
239}
240
241NetAddressCollection *TetherController::getDnsForwarders() {
242    return mDnsForwarders;
243}
244
245int TetherController::applyDnsInterfaces() {
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    if (!isIfaceName(interface)) {
278        errno = ENOENT;
279        return -1;
280    }
281    mInterfaces->push_back(strdup(interface));
282
283    if (applyDnsInterfaces()) {
284        InterfaceCollection::iterator it;
285        for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
286            if (!strcmp(interface, *it)) {
287                free(*it);
288                mInterfaces->erase(it);
289                break;
290            }
291        }
292        return -1;
293    } else {
294        return 0;
295    }
296}
297
298int TetherController::untetherInterface(const char *interface) {
299    InterfaceCollection::iterator it;
300
301    ALOGD("untetherInterface(%s)", interface);
302
303    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
304        if (!strcmp(interface, *it)) {
305            free(*it);
306            mInterfaces->erase(it);
307
308            return applyDnsInterfaces();
309        }
310    }
311    errno = ENOENT;
312    return -1;
313}
314
315InterfaceCollection *TetherController::getTetheredInterfaceList() {
316    return mInterfaces;
317}
318