TetherController.cpp revision 9589a4c6e0b6a5ec60c65b248e7deff2805749b2 
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    mDhcpcdPid = 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
100int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
101    if (mDaemonPid != 0) {
102        ALOGE("Tethering already started");
103        errno = EBUSY;
104        return -1;
105    }
106
107    ALOGD("Starting tethering services");
108
109    pid_t pid;
110    int pipefd[2];
111
112    if (pipe(pipefd) < 0) {
113        ALOGE("pipe failed (%s)", strerror(errno));
114        return -1;
115    }
116
117    /*
118     * TODO: Create a monitoring thread to handle and restart
119     * the daemon if it exits prematurely
120     */
121    if ((pid = fork()) < 0) {
122        ALOGE("fork failed (%s)", strerror(errno));
123        close(pipefd[0]);
124        close(pipefd[1]);
125        return -1;
126    }
127
128    if (!pid) {
129        close(pipefd[1]);
130        if (pipefd[0] != STDIN_FILENO) {
131            if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
132                ALOGE("dup2 failed (%s)", strerror(errno));
133                return -1;
134            }
135            close(pipefd[0]);
136        }
137
138        int num_processed_args = 7 + (num_addrs/2) + 1; // 1 null for termination
139        char **args = (char **)malloc(sizeof(char *) * num_processed_args);
140        args[num_processed_args - 1] = NULL;
141        args[0] = (char *)"/system/bin/dnsmasq";
142        args[1] = (char *)"--keep-in-foreground";
143        args[2] = (char *)"--no-resolv";
144        args[3] = (char *)"--no-poll";
145        // TODO: pipe through metered status from ConnService
146        args[4] = (char *)"--dhcp-option-force=43,ANDROID_METERED";
147        args[5] = (char *)"--pid-file";
148        args[6] = (char *)"";
149
150        int nextArg = 7;
151        for (int addrIndex=0; addrIndex < num_addrs;) {
152            char *start = strdup(inet_ntoa(addrs[addrIndex++]));
153            char *end = strdup(inet_ntoa(addrs[addrIndex++]));
154            asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
155        }
156
157        if (execv(args[0], args)) {
158            ALOGE("execl failed (%s)", strerror(errno));
159        }
160        ALOGE("Should never get here!");
161        free(args);
162        return 0;
163    } else {
164        close(pipefd[0]);
165        mDaemonPid = pid;
166        mDaemonFd = pipefd[1];
167        ALOGD("Tethering services running");
168    }
169
170    return 0;
171}
172
173int TetherController::stopTethering() {
174
175    if (mDaemonPid == 0) {
176        ALOGE("Tethering already stopped");
177        return 0;
178    }
179
180    ALOGD("Stopping tethering services");
181
182    kill(mDaemonPid, SIGTERM);
183    waitpid(mDaemonPid, NULL, 0);
184    mDaemonPid = 0;
185    close(mDaemonFd);
186    mDaemonFd = -1;
187    ALOGD("Tethering services stopped");
188    return 0;
189}
190int TetherController::startReverseTethering(const char* iface) {
191    if (mDhcpcdPid != 0) {
192        LOGE("Reverse tethering already started");
193        errno = EBUSY;
194        return -1;
195    }
196
197    LOGD("TetherController::startReverseTethering, Starting reverse tethering");
198
199    /*
200     * TODO: Create a monitoring thread to handle and restart
201     * the daemon if it exits prematurely
202     */
203    //cleanup the dhcp result
204    char dhcp_result_name[64];
205    snprintf(dhcp_result_name, sizeof(dhcp_result_name) - 1, "dhcp.%s.result", iface);
206    property_set(dhcp_result_name, "");
207
208    pid_t pid;
209    if ((pid = fork()) < 0) {
210        LOGE("fork failed (%s)", strerror(errno));
211        return -1;
212    }
213
214    if (!pid) {
215
216        char *args[10];
217        int argc = 0;
218        args[argc++] = "/system/bin/dhcpcd";
219        char host_name[128];
220        if (property_get("net.hostname", host_name, NULL) && (host_name[0] != '\0'))
221        {
222            args[argc++] = "-h";
223            args[argc++] = host_name;
224        }
225        args[argc++] = (char*)iface;
226        args[argc] = NULL;
227        if (execv(args[0], args)) {
228            LOGE("startReverseTethering, execv failed (%s)", strerror(errno));
229        }
230        LOGE("startReverseTethering, Should never get here!");
231        return 0;
232    } else {
233        mDhcpcdPid = pid;
234        LOGD("Reverse Tethering running, pid:%d", pid);
235    }
236    return 0;
237}
238int TetherController::stopReverseTethering() {
239
240    if (mDhcpcdPid == 0) {
241        LOGE("Tethering already stopped");
242        return 0;
243    }
244
245    LOGD("Stopping tethering services");
246
247    kill(mDhcpcdPid, SIGTERM);
248    waitpid(mDhcpcdPid, NULL, 0);
249    mDhcpcdPid = 0;
250    LOGD("Tethering services stopped");
251    return 0;
252}
253bool TetherController::isTetheringStarted() {
254    return (mDaemonPid == 0 ? false : true);
255}
256
257#define MAX_CMD_SIZE 1024
258
259int TetherController::setDnsForwarders(char **servers, int numServers) {
260    int i;
261    char daemonCmd[MAX_CMD_SIZE];
262
263    strcpy(daemonCmd, "update_dns");
264    int cmdLen = strlen(daemonCmd);
265
266    mDnsForwarders->clear();
267    for (i = 0; i < numServers; i++) {
268        ALOGD("setDnsForwarders(%d = '%s')", i, servers[i]);
269
270        struct in_addr a;
271
272        if (!inet_aton(servers[i], &a)) {
273            ALOGE("Failed to parse DNS server '%s'", servers[i]);
274            mDnsForwarders->clear();
275            return -1;
276        }
277
278        cmdLen += strlen(servers[i]);
279        if (cmdLen + 2 >= MAX_CMD_SIZE) {
280            ALOGD("Too many DNS servers listed");
281            break;
282        }
283
284        strcat(daemonCmd, ":");
285        strcat(daemonCmd, servers[i]);
286        mDnsForwarders->push_back(a);
287    }
288
289    if (mDaemonFd != -1) {
290        ALOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
291        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
292            ALOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
293            mDnsForwarders->clear();
294            return -1;
295        }
296    }
297    return 0;
298}
299
300NetAddressCollection *TetherController::getDnsForwarders() {
301    return mDnsForwarders;
302}
303
304int TetherController::tetherInterface(const char *interface) {
305    mInterfaces->push_back(strdup(interface));
306    return 0;
307}
308
309int TetherController::untetherInterface(const char *interface) {
310    InterfaceCollection::iterator it;
311
312    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
313        if (!strcmp(interface, *it)) {
314            free(*it);
315            mInterfaces->erase(it);
316            return 0;
317        }
318    }
319    errno = ENOENT;
320    return -1;
321}
322
323InterfaceCollection *TetherController::getTetheredInterfaceList() {
324    return mInterfaces;
325}
326