dhcp_utils.c revision 9d157870345fa18ee7e639a85f6bcc4afb50c648 
1/*
2 * Copyright 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/* Utilities for managing the dhcpcd DHCP client daemon */
18
19#include <stdio.h>
20#include <stdlib.h>
21#include <string.h>
22#include <unistd.h>
23#include <arpa/inet.h>
24#include <netinet/in.h>
25
26#include <cutils/properties.h>
27
28static const char DAEMON_NAME[]        = "dhcpcd";
29static const char DAEMON_PROP_NAME[]   = "init.svc.dhcpcd";
30static const char HOSTNAME_PROP_NAME[] = "net.hostname";
31static const char DHCP_PROP_NAME_PREFIX[]  = "dhcp";
32static const int NAP_TIME = 200;   /* wait for 200ms at a time */
33                                  /* when polling for property values */
34static const char DAEMON_NAME_RENEW[]  = "iprenew";
35static char errmsg[100];
36
37/*
38 * Wait for a system property to be assigned a specified value.
39 * If desired_value is NULL, then just wait for the property to
40 * be created with any value. maxwait is the maximum amount of
41 * time in seconds to wait before giving up.
42 */
43static int wait_for_property(const char *name, const char *desired_value, int maxwait)
44{
45    char value[PROPERTY_VALUE_MAX] = {'\0'};
46    int maxnaps = (maxwait * 1000) / NAP_TIME;
47
48    if (maxnaps < 1) {
49        maxnaps = 1;
50    }
51
52    while (maxnaps-- > 0) {
53        usleep(NAP_TIME * 1000);
54        if (property_get(name, value, NULL)) {
55            if (desired_value == NULL ||
56                    strcmp(value, desired_value) == 0) {
57                return 0;
58            }
59        }
60    }
61    return -1; /* failure */
62}
63
64static int fill_ip_info(const char *interface,
65                     char *ipaddr,
66                     char *gateway,
67                     uint32_t *prefixLength,
68                     char *dns1,
69                     char *dns2,
70                     char *server,
71                     uint32_t  *lease)
72{
73    char prop_name[PROPERTY_KEY_MAX];
74    char prop_value[PROPERTY_VALUE_MAX];
75
76    snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, interface);
77    property_get(prop_name, ipaddr, NULL);
78
79    snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, interface);
80    property_get(prop_name, gateway, NULL);
81
82    snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, interface);
83    if (property_get(prop_name, prop_value, NULL)) {
84        int p;
85        // this conversion is v4 only, but this dhcp client is v4 only anyway
86        in_addr_t mask = ntohl(inet_addr(prop_value));
87        // Check netmask is a valid IP address.  ntohl gives NONE response (all 1's) for
88        // non 255.255.255.255 inputs.  if we get that value check if it is legit..
89        if (mask == INADDR_NONE && strcmp(prop_value, "255.255.255.255") != 0) {
90            snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
91            return -1;
92        }
93        for (p = 0; p < 32; p++) {
94            if (mask == 0) break;
95            // check for non-contiguous netmask, e.g., 255.254.255.0
96            if ((mask & 0x80000000) == 0) {
97                snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
98                return -1;
99            }
100            mask = mask << 1;
101        }
102        *prefixLength = p;
103    }
104    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns1", DHCP_PROP_NAME_PREFIX, interface);
105    property_get(prop_name, dns1, NULL);
106
107    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns2", DHCP_PROP_NAME_PREFIX, interface);
108    property_get(prop_name, dns2, NULL);
109
110    snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, interface);
111    property_get(prop_name, server, NULL);
112
113    snprintf(prop_name, sizeof(prop_name), "%s.%s.leasetime", DHCP_PROP_NAME_PREFIX, interface);
114    if (property_get(prop_name, prop_value, NULL)) {
115        *lease = atol(prop_value);
116    }
117    return 0;
118}
119
120static const char *ipaddr_to_string(in_addr_t addr)
121{
122    struct in_addr in_addr;
123
124    in_addr.s_addr = addr;
125    return inet_ntoa(in_addr);
126}
127
128/*
129 * Start the dhcp client daemon, and wait for it to finish
130 * configuring the interface.
131 */
132int dhcp_do_request(const char *interface,
133                    char *ipaddr,
134                    char *gateway,
135                    uint32_t *prefixLength,
136                    char *dns1,
137                    char *dns2,
138                    char *server,
139                    uint32_t  *lease)
140{
141    char result_prop_name[PROPERTY_KEY_MAX];
142    char daemon_prop_name[PROPERTY_KEY_MAX];
143    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
144    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
145    const char *ctrl_prop = "ctl.start";
146    const char *desired_status = "running";
147
148    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
149            DHCP_PROP_NAME_PREFIX,
150            interface);
151
152    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
153            DAEMON_PROP_NAME,
154            interface);
155
156    /* Erase any previous setting of the dhcp result property */
157    property_set(result_prop_name, "");
158
159    /* Start the daemon and wait until it's ready */
160    if (property_get(HOSTNAME_PROP_NAME, prop_value, NULL) && (prop_value[0] != '\0'))
161        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:-h %s %s", DAEMON_NAME, interface,
162                 prop_value, interface);
163    else
164        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:%s", DAEMON_NAME, interface, interface);
165    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
166    property_set(ctrl_prop, daemon_cmd);
167    if (wait_for_property(daemon_prop_name, desired_status, 10) < 0) {
168        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
169        return -1;
170    }
171
172    /* Wait for the daemon to return a result */
173    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
174        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
175        return -1;
176    }
177
178    if (!property_get(result_prop_name, prop_value, NULL)) {
179        /* shouldn't ever happen, given the success of wait_for_property() */
180        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
181        return -1;
182    }
183    if (strcmp(prop_value, "ok") == 0) {
184        char dns_prop_name[PROPERTY_KEY_MAX];
185        if (fill_ip_info(interface, ipaddr, gateway, prefixLength, dns1, dns2, server, lease)
186                == -1) {
187            return -1;
188        }
189
190        /* copy dns data to system properties - TODO - remove this after we have async
191         * notification of renewal's */
192        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns1", interface);
193        property_set(dns_prop_name, *dns1 ? ipaddr_to_string(*dns1) : "");
194        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns2", interface);
195        property_set(dns_prop_name, *dns2 ? ipaddr_to_string(*dns2) : "");
196        return 0;
197    } else {
198        snprintf(errmsg, sizeof(errmsg), "DHCP result was %s", prop_value);
199        return -1;
200    }
201}
202
203/**
204 * Stop the DHCP client daemon.
205 */
206int dhcp_stop(const char *interface)
207{
208    char result_prop_name[PROPERTY_KEY_MAX];
209    char daemon_prop_name[PROPERTY_KEY_MAX];
210    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
211    const char *ctrl_prop = "ctl.stop";
212    const char *desired_status = "stopped";
213
214    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
215            DHCP_PROP_NAME_PREFIX,
216            interface);
217
218    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
219            DAEMON_PROP_NAME,
220            interface);
221
222    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, interface);
223
224    /* Stop the daemon and wait until it's reported to be stopped */
225    property_set(ctrl_prop, daemon_cmd);
226    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
227        return -1;
228    }
229    property_set(result_prop_name, "failed");
230    return 0;
231}
232
233/**
234 * Release the current DHCP client lease.
235 */
236int dhcp_release_lease(const char *interface)
237{
238    char daemon_prop_name[PROPERTY_KEY_MAX];
239    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
240    const char *ctrl_prop = "ctl.stop";
241    const char *desired_status = "stopped";
242
243    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
244            DAEMON_PROP_NAME,
245            interface);
246
247    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, interface);
248
249    /* Stop the daemon and wait until it's reported to be stopped */
250    property_set(ctrl_prop, daemon_cmd);
251    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
252        return -1;
253    }
254    return 0;
255}
256
257char *dhcp_get_errmsg() {
258    return errmsg;
259}
260
261/**
262 * Run WiMAX dhcp renew service.
263 * "wimax_renew" service shoud be included in init.rc.
264 */
265int dhcp_do_request_renew(const char *interface,
266                    in_addr_t *ipaddr,
267                    in_addr_t *gateway,
268                    in_addr_t *mask,
269                    in_addr_t *dns1,
270                    in_addr_t *dns2,
271                    in_addr_t *server,
272                    uint32_t  *lease)
273{
274    char result_prop_name[PROPERTY_KEY_MAX];
275    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
276    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
277    const char *ctrl_prop = "ctl.start";
278
279    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
280            DHCP_PROP_NAME_PREFIX,
281            interface);
282
283    /* Erase any previous setting of the dhcp result property */
284    property_set(result_prop_name, "");
285
286    /* Start the renew daemon and wait until it's ready */
287    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:%s", DAEMON_NAME_RENEW, interface, interface);
288    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
289    property_set(ctrl_prop, daemon_cmd);
290
291    /* Wait for the daemon to return a result */
292    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
293        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP Renew to finish");
294        return -1;
295    }
296
297    if (!property_get(result_prop_name, prop_value, NULL)) {
298        /* shouldn't ever happen, given the success of wait_for_property() */
299        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP Renew result property was not set");
300        return -1;
301    }
302    if (strcmp(prop_value, "ok") == 0) {
303        fill_ip_info(interface, ipaddr, gateway, mask, dns1, dns2, server, lease);
304        return 0;
305    } else {
306        snprintf(errmsg, sizeof(errmsg), "DHCP Renew result was %s", prop_value);
307        return -1;
308    }
309}
310