dhcp_utils.c revision a329b4296cab06ea0b6e95065d8eabb82d3fd76d 
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/* interface suffix on dhcpcd */
37#define MAX_DAEMON_SUFFIX 25
38
39/*
40 * Wait for a system property to be assigned a specified value.
41 * If desired_value is NULL, then just wait for the property to
42 * be created with any value. maxwait is the maximum amount of
43 * time in seconds to wait before giving up.
44 */
45static int wait_for_property(const char *name, const char *desired_value, int maxwait)
46{
47    char value[PROPERTY_VALUE_MAX] = {'\0'};
48    int maxnaps = (maxwait * 1000) / NAP_TIME;
49
50    if (maxnaps < 1) {
51        maxnaps = 1;
52    }
53
54    while (maxnaps-- > 0) {
55        usleep(NAP_TIME * 1000);
56        if (property_get(name, value, NULL)) {
57            if (desired_value == NULL ||
58                    strcmp(value, desired_value) == 0) {
59                return 0;
60            }
61        }
62    }
63    return -1; /* failure */
64}
65
66static int fill_ip_info(const char *interface,
67                     char *ipaddr,
68                     char *gateway,
69                     uint32_t *prefixLength,
70                     char *dns1,
71                     char *dns2,
72                     char *server,
73                     uint32_t  *lease)
74{
75    char prop_name[PROPERTY_KEY_MAX];
76    char prop_value[PROPERTY_VALUE_MAX];
77
78    snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, interface);
79    property_get(prop_name, ipaddr, NULL);
80
81    snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, interface);
82    property_get(prop_name, gateway, NULL);
83
84    snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, interface);
85    property_get(prop_name, server, NULL);
86
87    //TODO: Handle IPv6 when we change system property usage
88    if (strcmp(gateway, "0.0.0.0") == 0) {
89        //DHCP server is our best bet as gateway
90        strncpy(gateway, server, PROPERTY_VALUE_MAX);
91    }
92
93    snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, interface);
94    if (property_get(prop_name, prop_value, NULL)) {
95        int p;
96        // this conversion is v4 only, but this dhcp client is v4 only anyway
97        in_addr_t mask = ntohl(inet_addr(prop_value));
98        // Check netmask is a valid IP address.  ntohl gives NONE response (all 1's) for
99        // non 255.255.255.255 inputs.  if we get that value check if it is legit..
100        if (mask == INADDR_NONE && strcmp(prop_value, "255.255.255.255") != 0) {
101            snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
102            return -1;
103        }
104        for (p = 0; p < 32; p++) {
105            if (mask == 0) break;
106            // check for non-contiguous netmask, e.g., 255.254.255.0
107            if ((mask & 0x80000000) == 0) {
108                snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
109                return -1;
110            }
111            mask = mask << 1;
112        }
113        *prefixLength = p;
114    }
115    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns1", DHCP_PROP_NAME_PREFIX, interface);
116    property_get(prop_name, dns1, NULL);
117
118    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns2", DHCP_PROP_NAME_PREFIX, interface);
119    property_get(prop_name, dns2, NULL);
120
121    snprintf(prop_name, sizeof(prop_name), "%s.%s.leasetime", DHCP_PROP_NAME_PREFIX, interface);
122    if (property_get(prop_name, prop_value, NULL)) {
123        *lease = atol(prop_value);
124    }
125    return 0;
126}
127
128static const char *ipaddr_to_string(in_addr_t addr)
129{
130    struct in_addr in_addr;
131
132    in_addr.s_addr = addr;
133    return inet_ntoa(in_addr);
134}
135
136void get_daemon_suffix(const char *interface, char *daemon_suffix) {
137    /* Use p2p suffix for any p2p interface. */
138    if (strncmp(interface, "p2p",3) == 0) {
139        sprintf(daemon_suffix, "p2p");
140    } else {
141        snprintf(daemon_suffix, MAX_DAEMON_SUFFIX, "%s", interface);
142    }
143}
144
145/*
146 * Start the dhcp client daemon, and wait for it to finish
147 * configuring the interface.
148 */
149int dhcp_do_request(const char *interface,
150                    char *ipaddr,
151                    char *gateway,
152                    uint32_t *prefixLength,
153                    char *dns1,
154                    char *dns2,
155                    char *server,
156                    uint32_t  *lease)
157{
158    char result_prop_name[PROPERTY_KEY_MAX];
159    char daemon_prop_name[PROPERTY_KEY_MAX];
160    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
161    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
162    const char *ctrl_prop = "ctl.start";
163    const char *desired_status = "running";
164    char daemon_suffix[MAX_DAEMON_SUFFIX];
165
166    get_daemon_suffix(interface, daemon_suffix);
167
168    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
169            DHCP_PROP_NAME_PREFIX,
170            interface);
171
172    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
173            DAEMON_PROP_NAME,
174            daemon_suffix);
175
176    /* Erase any previous setting of the dhcp result property */
177    property_set(result_prop_name, "");
178
179    /* Start the daemon and wait until it's ready */
180    if (property_get(HOSTNAME_PROP_NAME, prop_value, NULL) && (prop_value[0] != '\0'))
181        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:-h %s %s", DAEMON_NAME, daemon_suffix,
182                 prop_value, interface);
183    else
184        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:%s", DAEMON_NAME, daemon_suffix, interface);
185    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
186    property_set(ctrl_prop, daemon_cmd);
187    if (wait_for_property(daemon_prop_name, desired_status, 10) < 0) {
188        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
189        return -1;
190    }
191
192    /* Wait for the daemon to return a result */
193    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
194        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
195        return -1;
196    }
197
198    if (!property_get(result_prop_name, prop_value, NULL)) {
199        /* shouldn't ever happen, given the success of wait_for_property() */
200        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
201        return -1;
202    }
203    if (strcmp(prop_value, "ok") == 0) {
204        char dns_prop_name[PROPERTY_KEY_MAX];
205        if (fill_ip_info(interface, ipaddr, gateway, prefixLength, dns1, dns2, server, lease)
206                == -1) {
207            return -1;
208        }
209
210        /* copy dns data to system properties - TODO - remove this after we have async
211         * notification of renewal's */
212        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns1", interface);
213        property_set(dns_prop_name, *dns1 ? ipaddr_to_string(*dns1) : "");
214        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns2", interface);
215        property_set(dns_prop_name, *dns2 ? ipaddr_to_string(*dns2) : "");
216        return 0;
217    } else {
218        snprintf(errmsg, sizeof(errmsg), "DHCP result was %s", prop_value);
219        return -1;
220    }
221}
222
223/**
224 * Stop the DHCP client daemon.
225 */
226int dhcp_stop(const char *interface)
227{
228    char result_prop_name[PROPERTY_KEY_MAX];
229    char daemon_prop_name[PROPERTY_KEY_MAX];
230    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
231    const char *ctrl_prop = "ctl.stop";
232    const char *desired_status = "stopped";
233
234    char daemon_suffix[MAX_DAEMON_SUFFIX];
235
236    get_daemon_suffix(interface, daemon_suffix);
237
238    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
239            DHCP_PROP_NAME_PREFIX,
240            interface);
241
242    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
243            DAEMON_PROP_NAME,
244            daemon_suffix);
245
246    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, daemon_suffix);
247
248    /* Stop the daemon and wait until it's reported to be stopped */
249    property_set(ctrl_prop, daemon_cmd);
250    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
251        return -1;
252    }
253    property_set(result_prop_name, "failed");
254    return 0;
255}
256
257/**
258 * Release the current DHCP client lease.
259 */
260int dhcp_release_lease(const char *interface)
261{
262    char daemon_prop_name[PROPERTY_KEY_MAX];
263    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
264    const char *ctrl_prop = "ctl.stop";
265    const char *desired_status = "stopped";
266
267    char daemon_suffix[MAX_DAEMON_SUFFIX];
268
269    get_daemon_suffix(interface, daemon_suffix);
270
271    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
272            DAEMON_PROP_NAME,
273            daemon_suffix);
274
275    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, daemon_suffix);
276
277    /* Stop the daemon and wait until it's reported to be stopped */
278    property_set(ctrl_prop, daemon_cmd);
279    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
280        return -1;
281    }
282    return 0;
283}
284
285char *dhcp_get_errmsg() {
286    return errmsg;
287}
288
289/**
290 * Run WiMAX dhcp renew service.
291 * "wimax_renew" service shoud be included in init.rc.
292 */
293int dhcp_do_request_renew(const char *interface,
294                    in_addr_t *ipaddr,
295                    in_addr_t *gateway,
296                    in_addr_t *mask,
297                    in_addr_t *dns1,
298                    in_addr_t *dns2,
299                    in_addr_t *server,
300                    uint32_t  *lease)
301{
302    char result_prop_name[PROPERTY_KEY_MAX];
303    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
304    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
305    const char *ctrl_prop = "ctl.start";
306
307    char daemon_suffix[MAX_DAEMON_SUFFIX];
308
309    get_daemon_suffix(interface, daemon_suffix);
310
311    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
312            DHCP_PROP_NAME_PREFIX,
313            interface);
314
315    /* Erase any previous setting of the dhcp result property */
316    property_set(result_prop_name, "");
317
318    /* Start the renew daemon and wait until it's ready */
319    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:%s", DAEMON_NAME_RENEW,
320            daemon_suffix, interface);
321    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
322    property_set(ctrl_prop, daemon_cmd);
323
324    /* Wait for the daemon to return a result */
325    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
326        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP Renew to finish");
327        return -1;
328    }
329
330    if (!property_get(result_prop_name, prop_value, NULL)) {
331        /* shouldn't ever happen, given the success of wait_for_property() */
332        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP Renew result property was not set");
333        return -1;
334    }
335    if (strcmp(prop_value, "ok") == 0) {
336        fill_ip_info(interface, ipaddr, gateway, mask, dns1, dns2, server, lease);
337        return 0;
338    } else {
339        snprintf(errmsg, sizeof(errmsg), "DHCP Renew result was %s", prop_value);
340        return -1;
341    }
342}
343