TetherController.cpp revision ff2c0d8c13457e43f0d4bf06d3177271aac104c1 
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
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    LOGD("Setting IP forward enable = %d", enable);
57    int fd = open("/proc/sys/net/ipv4/ip_forward", O_WRONLY);
58    if (fd < 0) {
59        LOGE("Failed to open ip_forward (%s)", strerror(errno));
60        return -1;
61    }
62
63    if (write(fd, (enable ? "1" : "0"), 1) != 1) {
64        LOGE("Failed to write ip_forward (%s)", strerror(errno));
65        close(fd);
66        return -1;
67    }
68    close(fd);
69    return 0;
70}
71
72bool TetherController::getIpFwdEnabled() {
73    int fd = open("/proc/sys/net/ipv4/ip_forward", O_RDONLY);
74
75    if (fd < 0) {
76        LOGE("Failed to open ip_forward (%s)", strerror(errno));
77        return false;
78    }
79
80    char enabled;
81    if (read(fd, &enabled, 1) != 1) {
82        LOGE("Failed to read ip_forward (%s)", strerror(errno));
83        close(fd);
84        return -1;
85    }
86
87    close(fd);
88    return (enabled  == '1' ? true : false);
89}
90
91int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
92    if (mDaemonPid != 0) {
93        LOGE("Tethering already started");
94        errno = EBUSY;
95        return -1;
96    }
97
98    LOGD("Starting tethering services");
99
100    pid_t pid;
101    int pipefd[2];
102
103    if (pipe(pipefd) < 0) {
104        LOGE("pipe failed (%s)", strerror(errno));
105        return -1;
106    }
107
108    /*
109     * TODO: Create a monitoring thread to handle and restart
110     * the daemon if it exits prematurely
111     */
112    if ((pid = fork()) < 0) {
113        LOGE("fork failed (%s)", strerror(errno));
114        close(pipefd[0]);
115        close(pipefd[1]);
116        return -1;
117    }
118
119    if (!pid) {
120        close(pipefd[1]);
121        if (pipefd[0] != STDIN_FILENO) {
122            if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
123                LOGE("dup2 failed (%s)", strerror(errno));
124                return -1;
125            }
126            close(pipefd[0]);
127        }
128
129        int num_processed_args = 4 + (num_addrs/2) + 1; // 1 null for termination
130        char **args = (char **)malloc(sizeof(char *) * num_processed_args);
131        args[num_processed_args - 1] = NULL;
132        args[0] = (char *)"/system/bin/dnsmasq";
133        args[1] = (char *)"--no-daemon";
134        args[2] = (char *)"--no-resolv";
135        args[3] = (char *)"--no-poll";
136
137        int nextArg = 4;
138        for (int addrIndex=0; addrIndex < num_addrs;) {
139            char *start = strdup(inet_ntoa(addrs[addrIndex++]));
140            char *end = strdup(inet_ntoa(addrs[addrIndex++]));
141            asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
142        }
143
144        if (execv(args[0], args)) {
145            LOGE("execl failed (%s)", strerror(errno));
146        }
147        LOGE("Should never get here!");
148        free(args);
149        return 0;
150    } else {
151        close(pipefd[0]);
152        mDaemonPid = pid;
153        mDaemonFd = pipefd[1];
154        LOGD("Tethering services running");
155    }
156
157    return 0;
158}
159
160int TetherController::stopTethering() {
161
162    if (mDaemonPid == 0) {
163        LOGE("Tethering already stopped");
164        return 0;
165    }
166
167    LOGD("Stopping tethering services");
168
169    kill(mDaemonPid, SIGTERM);
170    waitpid(mDaemonPid, NULL, 0);
171    mDaemonPid = 0;
172    close(mDaemonFd);
173    mDaemonFd = -1;
174    LOGD("Tethering services stopped");
175    return 0;
176}
177
178bool TetherController::isTetheringStarted() {
179    return (mDaemonPid == 0 ? false : true);
180}
181
182#define MAX_CMD_SIZE 1024
183
184int TetherController::setDnsForwarders(char **servers, int numServers) {
185    int i;
186    char daemonCmd[MAX_CMD_SIZE];
187
188    strcpy(daemonCmd, "update_dns");
189    int cmdLen = strlen(daemonCmd);
190
191    mDnsForwarders->clear();
192    for (i = 0; i < numServers; i++) {
193        LOGD("setDnsForwarders(%d = '%s')", i, servers[i]);
194
195        struct in_addr a;
196
197        if (!inet_aton(servers[i], &a)) {
198            LOGE("Failed to parse DNS server '%s'", servers[i]);
199            mDnsForwarders->clear();
200            return -1;
201        }
202
203        cmdLen += strlen(servers[i]);
204        if (cmdLen + 2 >= MAX_CMD_SIZE) {
205            LOGD("Too many DNS servers listed");
206            break;
207        }
208
209        strcat(daemonCmd, ":");
210        strcat(daemonCmd, servers[i]);
211        mDnsForwarders->push_back(a);
212    }
213
214    if (mDaemonFd != -1) {
215        LOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
216        if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
217            LOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
218            mDnsForwarders->clear();
219            return -1;
220        }
221    }
222    return 0;
223}
224
225NetAddressCollection *TetherController::getDnsForwarders() {
226    return mDnsForwarders;
227}
228
229int TetherController::tetherInterface(const char *interface) {
230    mInterfaces->push_back(strdup(interface));
231    return 0;
232}
233
234int TetherController::untetherInterface(const char *interface) {
235    InterfaceCollection::iterator it;
236
237    for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
238        if (!strcmp(interface, *it)) {
239            free(*it);
240            mInterfaces->erase(it);
241            return 0;
242        }
243    }
244    errno = ENOENT;
245    return -1;
246}
247
248InterfaceCollection *TetherController::getTetheredInterfaceList() {
249    return mInterfaces;
250}
251