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
TetherController()36 TetherController::TetherController() {
37 mInterfaces = new InterfaceCollection();
38 mDnsForwarders = new NetAddressCollection();
39 mDaemonFd = -1;
40 mDaemonPid = 0;
41 }
42
~TetherController()43 TetherController::~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
setIpFwdEnabled(bool enable)54 int TetherController::setIpFwdEnabled(bool enable) {
55
56 LOGD("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 LOGE("Failed to open ip_forward (%s)", strerror(errno));
68 return -1;
69 }
70
71 if (write(fd, (enable ? "1" : "0"), 1) != 1) {
72 LOGE("Failed to write ip_forward (%s)", strerror(errno));
73 close(fd);
74 return -1;
75 }
76 close(fd);
77 return 0;
78 }
79
getIpFwdEnabled()80 bool TetherController::getIpFwdEnabled() {
81 int fd = open("/proc/sys/net/ipv4/ip_forward", O_RDONLY);
82
83 if (fd < 0) {
84 LOGE("Failed to open ip_forward (%s)", strerror(errno));
85 return false;
86 }
87
88 char enabled;
89 if (read(fd, &enabled, 1) != 1) {
90 LOGE("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
startTethering(int num_addrs,struct in_addr * addrs)99 int TetherController::startTethering(int num_addrs, struct in_addr* addrs) {
100 if (mDaemonPid != 0) {
101 LOGE("Tethering already started");
102 errno = EBUSY;
103 return -1;
104 }
105
106 LOGD("Starting tethering services");
107
108 pid_t pid;
109 int pipefd[2];
110
111 if (pipe(pipefd) < 0) {
112 LOGE("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 LOGE("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 LOGE("dup2 failed (%s)", strerror(errno));
132 return -1;
133 }
134 close(pipefd[0]);
135 }
136
137 int num_processed_args = 4 + (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
145 int nextArg = 4;
146 for (int addrIndex=0; addrIndex < num_addrs;) {
147 char *start = strdup(inet_ntoa(addrs[addrIndex++]));
148 char *end = strdup(inet_ntoa(addrs[addrIndex++]));
149 asprintf(&(args[nextArg++]),"--dhcp-range=%s,%s,1h", start, end);
150 }
151
152 if (execv(args[0], args)) {
153 LOGE("execl failed (%s)", strerror(errno));
154 }
155 LOGE("Should never get here!");
156 free(args);
157 return 0;
158 } else {
159 close(pipefd[0]);
160 mDaemonPid = pid;
161 mDaemonFd = pipefd[1];
162 LOGD("Tethering services running");
163 }
164
165 return 0;
166 }
167
stopTethering()168 int TetherController::stopTethering() {
169
170 if (mDaemonPid == 0) {
171 LOGE("Tethering already stopped");
172 return 0;
173 }
174
175 LOGD("Stopping tethering services");
176
177 kill(mDaemonPid, SIGTERM);
178 waitpid(mDaemonPid, NULL, 0);
179 mDaemonPid = 0;
180 close(mDaemonFd);
181 mDaemonFd = -1;
182 LOGD("Tethering services stopped");
183 return 0;
184 }
185
isTetheringStarted()186 bool TetherController::isTetheringStarted() {
187 return (mDaemonPid == 0 ? false : true);
188 }
189
190 #define MAX_CMD_SIZE 1024
191
setDnsForwarders(char ** servers,int numServers)192 int TetherController::setDnsForwarders(char **servers, int numServers) {
193 int i;
194 char daemonCmd[MAX_CMD_SIZE];
195
196 strcpy(daemonCmd, "update_dns");
197 int cmdLen = strlen(daemonCmd);
198
199 mDnsForwarders->clear();
200 for (i = 0; i < numServers; i++) {
201 LOGD("setDnsForwarders(%d = '%s')", i, servers[i]);
202
203 struct in_addr a;
204
205 if (!inet_aton(servers[i], &a)) {
206 LOGE("Failed to parse DNS server '%s'", servers[i]);
207 mDnsForwarders->clear();
208 return -1;
209 }
210
211 cmdLen += strlen(servers[i]);
212 if (cmdLen + 2 >= MAX_CMD_SIZE) {
213 LOGD("Too many DNS servers listed");
214 break;
215 }
216
217 strcat(daemonCmd, ":");
218 strcat(daemonCmd, servers[i]);
219 mDnsForwarders->push_back(a);
220 }
221
222 if (mDaemonFd != -1) {
223 LOGD("Sending update msg to dnsmasq [%s]", daemonCmd);
224 if (write(mDaemonFd, daemonCmd, strlen(daemonCmd) +1) < 0) {
225 LOGE("Failed to send update command to dnsmasq (%s)", strerror(errno));
226 mDnsForwarders->clear();
227 return -1;
228 }
229 }
230 return 0;
231 }
232
getDnsForwarders()233 NetAddressCollection *TetherController::getDnsForwarders() {
234 return mDnsForwarders;
235 }
236
tetherInterface(const char * interface)237 int TetherController::tetherInterface(const char *interface) {
238 mInterfaces->push_back(strdup(interface));
239 return 0;
240 }
241
untetherInterface(const char * interface)242 int TetherController::untetherInterface(const char *interface) {
243 InterfaceCollection::iterator it;
244
245 for (it = mInterfaces->begin(); it != mInterfaces->end(); ++it) {
246 if (!strcmp(interface, *it)) {
247 free(*it);
248 mInterfaces->erase(it);
249 return 0;
250 }
251 }
252 errno = ENOENT;
253 return -1;
254 }
255
getTetheredInterfaceList()256 InterfaceCollection *TetherController::getTetheredInterfaceList() {
257 return mInterfaces;
258 }
259