TetherController.cpp revision a9d791f48e3472400ffad73dca88c28fb2f7aaa7 
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 "Fwmark.h"
35#include "NetdConstants.h"
36#include "Permission.h"
37#include "TetherController.h"
38
39TetherController::TetherController() {
40    mInterfaces = new InterfaceCollection();
41    mDnsNetId = 0;
42    mDnsForwarders = new NetAddressCollection();
43    mDaemonFd = -1;
44    mDaemonPid = 0;
45}
46
47TetherController::~TetherController() {
48    InterfaceCollection::iterator it;
49
50    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
51        free(*it);
52    }
53    mInterfaces->clear();
54
55    mDnsForwarders->clear();
56}
57
58int TetherController::setIpFwdEnabled(bool enable) {
59
60    ALOGD("Setting IP forward enable = %d", enable);
61
62    // In BP tools mode, do not disable IP forwarding
63    char bootmode[PROPERTY_VALUE_MAX] = {0};
64    property_get("ro.bootmode", bootmode, "unknown");
65    if ((enable == false) && (0 == strcmp("bp-tools", bootmode))) {
66        return 0;
67    }
68
69    int fd = open("/proc/sys/net/ipv4/ip_forward", O_WRONLY);
70    if (fd < 0) {
71        ALOGE("Failed to open ip_forward (%s)", strerror(errno));
72        return -1;
73    }
74
75    if (write(fd, (enable ? "1" : "0"), 1) != 1) {
76        ALOGE("Failed to write ip_forward (%s)", strerror(errno));
77        close(fd);
78        return -1;
79    }
80    close(fd);
81    return 0;
82}
83
84bool TetherController::getIpFwdEnabled() {
85    int fd = open("/proc/sys/net/ipv4/ip_forward", O_RDONLY);
86
87    if (fd < 0) {
88        ALOGE("Failed to open ip_forward (%s)", strerror(errno));
89        return false;
90    }
91
92    char enabled;
93    if (read(fd, &enabled, 1) != 1) {
94        ALOGE("Failed to read ip_forward (%s)", strerror(errno));
95        close(fd);
96        return -1;
97    }
98
99    close(fd);
100    return (enabled  == '1' ? true : false);
101}
102
103#define TETHER_START_CONST_ARG        8
104
105int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
106    if (mDaemonPid != 0) {
107        ALOGE("Tethering already started");
108        errno = EBUSY;
109        return -1;
110    }
111
112    ALOGD("Starting tethering services");
113
114    pid_t pid;
115    int pipefd[2];
116
117    if (pipe(pipefd) < 0) {
118        ALOGE("pipe failed (%s)", strerror(errno));
119        return -1;
120    }
121
122    /*
123     * TODO: Create a monitoring thread to handle and restart
124     * the daemon if it exits prematurely
125     */
126    if ((pid = fork()) < 0) {
127        ALOGE("fork failed (%s)", strerror(errno));
128        close(pipefd[0]);
129        close(pipefd[1]);
130        return -1;
131    }
132
133    if (!pid) {
134        close(pipefd[1]);
135        if (pipefd[0] != STDIN_FILENO) {
136            if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
137                ALOGE("dup2 failed (%s)", strerror(errno));
138                return -1;
139            }
140            close(pipefd[0]);
141        }
142
143        int num_processed_args = TETHER_START_CONST_ARG + (num_addrs/2) + 1;
144        char **args = (char **)malloc(sizeof(char *) * num_processed_args);
145        args[num_processed_args - 1] = NULL;
146        args[0] = (char *)"/system/bin/dnsmasq";
147        args[1] = (char *)"--keep-in-foreground";
148        args[2] = (char *)"--no-resolv";
149        args[3] = (char *)"--no-poll";
150        args[4] = (char *)"--dhcp-authoritative";
151        // TODO: pipe through metered status from ConnService
152        args[5] = (char *)"--dhcp-option-force=43,ANDROID_METERED";
153        args[6] = (char *)"--pid-file";
154        args[7] = (char *)"";
155
156        int nextArg = TETHER_START_CONST_ARG;
157        for (int addrIndex=0; addrIndex < num_addrs;) {
158            char *start = strdup(inet_ntoa(addrs[addrIndex++]));
159            char *end = strdup(inet_ntoa(addrs[addrIndex++]));
160            asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
161            free(start);
162            free(end);
163        }
164
165        if (execv(args[0], args)) {
166            ALOGE("execl failed (%s)", strerror(errno));
167        }
168        ALOGE("Should never get here!");
169        _exit(-1);
170    } else {
171        close(pipefd[0]);
172        mDaemonPid = pid;
173        mDaemonFd = pipefd[1];
174        applyDnsInterfaces();
175        ALOGD("Tethering services running");
176    }
177
178    return 0;
179}
180
181int TetherController::stopTethering() {
182
183    if (mDaemonPid == 0) {
184        ALOGE("Tethering already stopped");
185        return 0;
186    }
187
188    ALOGD("Stopping tethering services");
189
190    kill(mDaemonPid, SIGTERM);
191    waitpid(mDaemonPid, NULL, 0);
192    mDaemonPid = 0;
193    close(mDaemonFd);
194    mDaemonFd = -1;
195    ALOGD("Tethering services stopped");
196    return 0;
197}
198
199bool TetherController::isTetheringStarted() {
200    return (mDaemonPid == 0 ? false : true);
201}
202
203#define MAX_CMD_SIZE 1024
204
205int TetherController::setDnsForwarders(unsigned netId, char **servers, int numServers) {
206    int i;
207    char daemonCmd[MAX_CMD_SIZE];
208
209    Fwmark fwmark;
210    fwmark.netId = netId;
211    fwmark.explicitlySelected = true;
212    fwmark.protectedFromVpn = true;
213    fwmark.permission = PERMISSION_SYSTEM;
214
215    snprintf(daemonCmd, sizeof(daemonCmd), "update_dns:0x%x", fwmark.intValue);
216    int cmdLen = strlen(daemonCmd);
217
218    mDnsForwarders->clear();
219    for (i = 0; i < numServers; i++) {
220        ALOGD("setDnsForwarders(0x%x %d = '%s')", fwmark.intValue, i, servers[i]);
221
222        struct in_addr a;
223
224        if (!inet_aton(servers[i], &a)) {
225            ALOGE("Failed to parse DNS server '%s'", servers[i]);
226            mDnsForwarders->clear();
227            return -1;
228        }
229
230        cmdLen += (strlen(servers[i]) + 1);
231        if (cmdLen + 1 >= MAX_CMD_SIZE) {
232            ALOGD("Too many DNS servers listed");
233            break;
234        }
235
236        strcat(daemonCmd, ":");
237        strcat(daemonCmd, servers[i]);
238        mDnsForwarders->push_back(a);
239    }
240
241    mDnsNetId = netId;
242    if (mDaemonFd != -1) {
243        ALOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
244        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
245            ALOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
246            mDnsForwarders->clear();
247            return -1;
248        }
249    }
250    return 0;
251}
252
253unsigned TetherController::getDnsNetId() {
254    return mDnsNetId;
255}
256
257NetAddressCollection *TetherController::getDnsForwarders() {
258    return mDnsForwarders;
259}
260
261int TetherController::applyDnsInterfaces() {
262    char daemonCmd[MAX_CMD_SIZE];
263
264    strcpy(daemonCmd, "update_ifaces");
265    int cmdLen = strlen(daemonCmd);
266    InterfaceCollection::iterator it;
267    bool haveInterfaces = false;
268
269    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
270        cmdLen += (strlen(*it) + 1);
271        if (cmdLen + 1 >= MAX_CMD_SIZE) {
272            ALOGD("Too many DNS ifaces listed");
273            break;
274        }
275
276        strcat(daemonCmd, ":");
277        strcat(daemonCmd, *it);
278        haveInterfaces = true;
279    }
280
281    if ((mDaemonFd != -1) && haveInterfaces) {
282        ALOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
283        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
284            ALOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
285            return -1;
286        }
287    }
288    return 0;
289}
290
291int TetherController::tetherInterface(const char *interface) {
292    ALOGD("tetherInterface(%s)", interface);
293    if (!isIfaceName(interface)) {
294        errno = ENOENT;
295        return -1;
296    }
297    mInterfaces->push_back(strdup(interface));
298
299    if (applyDnsInterfaces()) {
300        InterfaceCollection::iterator it;
301        for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
302            if (!strcmp(interface, *it)) {
303                free(*it);
304                mInterfaces->erase(it);
305                break;
306            }
307        }
308        return -1;
309    } else {
310        return 0;
311    }
312}
313
314int TetherController::untetherInterface(const char *interface) {
315    InterfaceCollection::iterator it;
316
317    ALOGD("untetherInterface(%s)", interface);
318
319    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
320        if (!strcmp(interface, *it)) {
321            free(*it);
322            mInterfaces->erase(it);
323
324            return applyDnsInterfaces();
325        }
326    }
327    errno = ENOENT;
328    return -1;
329}
330
331InterfaceCollection *TetherController::getTetheredInterfaceList() {
332    return mInterfaces;
333}
334