TetherController.cpp revision 6df79da87b57437505eedd7fdf5359f9e67c38dd 
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
99int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
100    if (mDaemonPid != 0) {
101        ALOGE("Tethering already started");
102        errno = EBUSY;
103        return -1;
104    }
105
106    ALOGD("Starting tethering services");
107
108    pid_t pid;
109    int pipefd[2];
110
111    if (pipe(pipefd) < 0) {
112        ALOGE("pipe failed (%s)", strerror(errno));
113        return -1;
114    }
115
116    /*
117     * TODO: Create a monitoring thread to handle and restart
118     * the daemon if it exits prematurely
119     */
120    if ((pid = fork()) < 0) {
121        ALOGE("fork failed (%s)", strerror(errno));
122        close(pipefd[0]);
123        close(pipefd[1]);
124        return -1;
125    }
126
127    if (!pid) {
128        close(pipefd[1]);
129        if (pipefd[0] != STDIN_FILENO) {
130            if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
131                ALOGE("dup2 failed (%s)", strerror(errno));
132                return -1;
133            }
134            close(pipefd[0]);
135        }
136
137        int num_processed_args = 5 + (num_addrs/2) + 1; // 1 null for termination
138        char **args = (char **)malloc(sizeof(char *) * num_processed_args);
139        args[num_processed_args - 1] = NULL;
140        args[0] = (char *)"/system/bin/dnsmasq";
141        args[1] = (char *)"--no-daemon";
142        args[2] = (char *)"--no-resolv";
143        args[3] = (char *)"--no-poll";
144        // TODO: pipe through metered status from ConnService
145        args[4] = (char *)"--dhcp-option-force=43,ANDROID_METERED";
146
147        int nextArg = 5;
148        for (int addrIndex=0; addrIndex < num_addrs;) {
149            char *start = strdup(inet_ntoa(addrs[addrIndex++]));
150            char *end = strdup(inet_ntoa(addrs[addrIndex++]));
151            asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
152        }
153
154        if (execv(args[0], args)) {
155            ALOGE("execl failed (%s)", strerror(errno));
156        }
157        ALOGE("Should never get here!");
158        free(args);
159        return 0;
160    } else {
161        close(pipefd[0]);
162        mDaemonPid = pid;
163        mDaemonFd = pipefd[1];
164        ALOGD("Tethering services running");
165    }
166
167    return 0;
168}
169
170int TetherController::stopTethering() {
171
172    if (mDaemonPid == 0) {
173        ALOGE("Tethering already stopped");
174        return 0;
175    }
176
177    ALOGD("Stopping tethering services");
178
179    kill(mDaemonPid, SIGTERM);
180    waitpid(mDaemonPid, NULL, 0);
181    mDaemonPid = 0;
182    close(mDaemonFd);
183    mDaemonFd = -1;
184    ALOGD("Tethering services stopped");
185    return 0;
186}
187
188bool TetherController::isTetheringStarted() {
189    return (mDaemonPid == 0 ? false : true);
190}
191
192#define MAX_CMD_SIZE 1024
193
194int TetherController::setDnsForwarders(char **servers, int numServers) {
195    int i;
196    char daemonCmd[MAX_CMD_SIZE];
197
198    strcpy(daemonCmd, "update_dns");
199    int cmdLen = strlen(daemonCmd);
200
201    mDnsForwarders->clear();
202    for (i = 0; i < numServers; i++) {
203        ALOGD("setDnsForwarders(%d = '%s')", i, servers[i]);
204
205        struct in_addr a;
206
207        if (!inet_aton(servers[i], &a)) {
208            ALOGE("Failed to parse DNS server '%s'", servers[i]);
209            mDnsForwarders->clear();
210            return -1;
211        }
212
213        cmdLen += strlen(servers[i]);
214        if (cmdLen + 2 >= MAX_CMD_SIZE) {
215            ALOGD("Too many DNS servers listed");
216            break;
217        }
218
219        strcat(daemonCmd, ":");
220        strcat(daemonCmd, servers[i]);
221        mDnsForwarders->push_back(a);
222    }
223
224    if (mDaemonFd != -1) {
225        ALOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
226        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
227            ALOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
228            mDnsForwarders->clear();
229            return -1;
230        }
231    }
232    return 0;
233}
234
235NetAddressCollection *TetherController::getDnsForwarders() {
236    return mDnsForwarders;
237}
238
239int TetherController::tetherInterface(const char *interface) {
240    mInterfaces->push_back(strdup(interface));
241    return 0;
242}
243
244int TetherController::untetherInterface(const char *interface) {
245    InterfaceCollection::iterator it;
246
247    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
248        if (!strcmp(interface, *it)) {
249            free(*it);
250            mInterfaces->erase(it);
251            return 0;
252        }
253    }
254    errno = ENOENT;
255    return -1;
256}
257
258InterfaceCollection *TetherController::getTetheredInterfaceList() {
259    return mInterfaces;
260}
261