TetherController.cpp revision 3208ea0b6cce28e7aef8459d548fd86df329e34f 
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
21#include <sys/socket.h>
22#include <sys/stat.h>
23#include <sys/types.h>
24#include <sys/wait.h>
25
26#include <netinet/in.h>
27#include <arpa/inet.h>
28
29#define LOG_TAG "TetherController"
30#include <cutils/log.h>
31
32
33#include "TetherController.h"
34
35TetherController::TetherController() {
36    mInterfaces = new InterfaceCollection();
37    mDnsForwarders = new NetAddressCollection();
38    mDaemonFd = -1;
39    mDaemonPid = 0;
40}
41
42TetherController::~TetherController() {
43    InterfaceCollection::iterator it;
44
45    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
46        free(*it);
47    }
48    mInterfaces->clear();
49
50    mDnsForwarders->clear();
51}
52
53int TetherController::setIpFwdEnabled(bool enable) {
54
55    LOGD("Setting IP forward enable = %d", enable);
56    int fd = open("/proc/sys/net/ipv4/ip_forward", O_WRONLY);
57    if (fd < 0) {
58        LOGE("Failed to open ip_forward (%s)", strerror(errno));
59        return -1;
60    }
61
62    if (write(fd, (enable ? "1" : "0"), 1) != 1) {
63        LOGE("Failed to write ip_forward (%s)", strerror(errno));
64        return -1;
65    }
66    close(fd);
67    return 0;
68}
69
70bool TetherController::getIpFwdEnabled() {
71    int fd = open("/proc/sys/net/ipv4/ip_forward", O_RDONLY);
72
73    if (fd < 0) {
74        LOGE("Failed to open ip_forward (%s)", strerror(errno));
75        return false;
76    }
77
78    char enabled;
79    if (read(fd, &enabled, 1) != 1) {
80        LOGE("Failed to read ip_forward (%s)", strerror(errno));
81        return -1;
82    }
83
84    close(fd);
85
86    return (enabled  == '1' ? true : false);
87}
88
89int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
90    if (mDaemonPid != 0) {
91        LOGE("Tethering already started");
92        errno = EBUSY;
93        return -1;
94    }
95
96    LOGD("Starting tethering services");
97
98    pid_t pid;
99    int pipefd[2];
100
101    if (pipe(pipefd) < 0) {
102        LOGE("pipe failed (%s)", strerror(errno));
103        return -1;
104    }
105
106    /*
107     * TODO: Create a monitoring thread to handle and restart
108     * the daemon if it exits prematurely
109     */
110    if ((pid = fork()) < 0) {
111        LOGE("fork failed (%s)", strerror(errno));
112        close(pipefd[0]);
113        close(pipefd[1]);
114        return -1;
115    }
116
117    if (!pid) {
118        close(pipefd[1]);
119        if (pipefd[0] != STDIN_FILENO) {
120            if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
121                LOGE("dup2 failed (%s)", strerror(errno));
122                return -1;
123            }
124            close(pipefd[0]);
125        }
126
127        int num_processed_args = 4 + (num_addrs/2) + 1; // 1 null for termination
128        char **args = (char **)malloc(sizeof(char *) * num_processed_args);
129        args[num_processed_args - 1] = NULL;
130        args[0] = (char *)"/system/bin/dnsmasq";
131        args[1] = (char *)"--no-daemon";
132        args[2] = (char *)"--no-resolv";
133        args[3] = (char *)"--no-poll";
134
135        int nextArg = 4;
136        for (int addrIndex=0; addrIndex < num_addrs;) {
137            char *start = strdup(inet_ntoa(addrs[addrIndex++]));
138            char *end = strdup(inet_ntoa(addrs[addrIndex++]));
139            asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
140        }
141
142        if (execv(args[0], args)) {
143            LOGE("execl failed (%s)", strerror(errno));
144        }
145        LOGE("Should never get here!");
146        free(args);
147        return 0;
148    } else {
149        close(pipefd[0]);
150        mDaemonPid = pid;
151        mDaemonFd = pipefd[1];
152        LOGD("Tethering services running");
153    }
154
155    return 0;
156}
157
158int TetherController::stopTethering() {
159
160    if (mDaemonPid == 0) {
161        LOGE("Tethering already stopped");
162        return 0;
163    }
164
165    LOGD("Stopping tethering services");
166
167    kill(mDaemonPid, SIGTERM);
168    waitpid(mDaemonPid, NULL, 0);
169    mDaemonPid = 0;
170    close(mDaemonFd);
171    mDaemonFd = -1;
172    LOGD("Tethering services stopped");
173    return 0;
174}
175
176bool TetherController::isTetheringStarted() {
177    return (mDaemonPid == 0 ? false : true);
178}
179
180#define MAX_CMD_SIZE 1024
181
182int TetherController::setDnsForwarders(char **servers, int numServers) {
183    int i;
184    char daemonCmd[MAX_CMD_SIZE];
185
186    strcpy(daemonCmd, "update_dns");
187    int cmdLen = strlen(daemonCmd);
188
189    mDnsForwarders->clear();
190    for (i = 0; i < numServers; i++) {
191        LOGD("setDnsForwarders(%d = '%s')", i, servers[i]);
192
193        struct in_addr a;
194
195        if (!inet_aton(servers[i], &a)) {
196            LOGE("Failed to parse DNS server '%s'", servers[i]);
197            mDnsForwarders->clear();
198            return -1;
199        }
200
201        cmdLen += strlen(servers[i]);
202        if (cmdLen + 2 >= MAX_CMD_SIZE) {
203            LOGD("Too many DNS servers listed");
204            break;
205        }
206
207        strcat(daemonCmd, ":");
208        strcat(daemonCmd, servers[i]);
209        mDnsForwarders->push_back(a);
210    }
211
212    if (mDaemonFd != -1) {
213        LOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
214        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
215            LOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
216            mDnsForwarders->clear();
217            return -1;
218        }
219    }
220    return 0;
221}
222
223NetAddressCollection *TetherController::getDnsForwarders() {
224    return mDnsForwarders;
225}
226
227int TetherController::tetherInterface(const char *interface) {
228    mInterfaces->push_back(strdup(interface));
229    return 0;
230}
231
232int TetherController::untetherInterface(const char *interface) {
233    InterfaceCollection::iterator it;
234
235    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
236        if (!strcmp(interface, *it)) {
237            free(*it);
238            mInterfaces->erase(it);
239            return 0;
240        }
241    }
242    errno = ENOENT;
243    return -1;
244}
245
246InterfaceCollection *TetherController::getTetheredInterfaceList() {
247    return mInterfaces;
248}
249