dhcp_utils.c revision 62d6f7486323fd2bd27299940a28f3c6de73f65d 
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 char DHCP_CONFIG_PATH[]   = "/system/etc/dhcpcd/dhcpcd.conf";
33static const int NAP_TIME = 200;   /* wait for 200ms at a time */
34                                  /* when polling for property values */
35static const char DAEMON_NAME_RENEW[]  = "iprenew";
36static char errmsg[100];
37/* interface length for dhcpcd daemon start (dhcpcd_<interface> as defined in init.rc file)
38 * or for filling up system properties dhcpcd.<interface>.ipaddress, dhcpcd.<interface>.dns1
39 * and other properties on a successful bind
40 */
41#define MAX_INTERFACE_LENGTH 25
42
43/*
44 * P2p interface names increase sequentially p2p-p2p0-1, p2p-p2p0-2.. after
45 * group formation. This does not work well with system properties which can quickly
46 * exhaust or for specifiying a dhcp start target in init which requires
47 * interface to be pre-defined in init.rc file.
48 *
49 * This function returns a common string p2p for all p2p interfaces.
50 */
51void get_p2p_interface_replacement(const char *interface, char *p2p_interface) {
52    /* Use p2p for any interface starting with p2p. */
53    if (strncmp(interface, "p2p",3) == 0) {
54        strncpy(p2p_interface, "p2p", MAX_INTERFACE_LENGTH);
55    } else {
56        strncpy(p2p_interface, interface, MAX_INTERFACE_LENGTH);
57    }
58}
59
60/*
61 * Wait for a system property to be assigned a specified value.
62 * If desired_value is NULL, then just wait for the property to
63 * be created with any value. maxwait is the maximum amount of
64 * time in seconds to wait before giving up.
65 */
66static int wait_for_property(const char *name, const char *desired_value, int maxwait)
67{
68    char value[PROPERTY_VALUE_MAX] = {'\0'};
69    int maxnaps = (maxwait * 1000) / NAP_TIME;
70
71    if (maxnaps < 1) {
72        maxnaps = 1;
73    }
74
75    while (maxnaps-- > 0) {
76        usleep(NAP_TIME * 1000);
77        if (property_get(name, value, NULL)) {
78            if (desired_value == NULL ||
79                    strcmp(value, desired_value) == 0) {
80                return 0;
81            }
82        }
83    }
84    return -1; /* failure */
85}
86
87static int fill_ip_info(const char *interface,
88                     char *ipaddr,
89                     char *gateway,
90                     uint32_t *prefixLength,
91                     char *dns1,
92                     char *dns2,
93                     char *server,
94                     uint32_t *lease,
95                     char *vendorInfo)
96{
97    char prop_name[PROPERTY_KEY_MAX];
98    char prop_value[PROPERTY_VALUE_MAX];
99    /* Interface name after converting p2p0-p2p0-X to p2p to reuse system properties */
100    char p2p_interface[MAX_INTERFACE_LENGTH];
101
102    get_p2p_interface_replacement(interface, p2p_interface);
103
104    snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, p2p_interface);
105    property_get(prop_name, ipaddr, NULL);
106
107    snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, p2p_interface);
108    property_get(prop_name, gateway, NULL);
109
110    snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, p2p_interface);
111    property_get(prop_name, server, NULL);
112
113    //TODO: Handle IPv6 when we change system property usage
114    if (strcmp(gateway, "0.0.0.0") == 0) {
115        //DHCP server is our best bet as gateway
116        strncpy(gateway, server, PROPERTY_VALUE_MAX);
117    }
118
119    snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, p2p_interface);
120    if (property_get(prop_name, prop_value, NULL)) {
121        int p;
122        // this conversion is v4 only, but this dhcp client is v4 only anyway
123        in_addr_t mask = ntohl(inet_addr(prop_value));
124        // Check netmask is a valid IP address.  ntohl gives NONE response (all 1's) for
125        // non 255.255.255.255 inputs.  if we get that value check if it is legit..
126        if (mask == INADDR_NONE && strcmp(prop_value, "255.255.255.255") != 0) {
127            snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
128            return -1;
129        }
130        for (p = 0; p < 32; p++) {
131            if (mask == 0) break;
132            // check for non-contiguous netmask, e.g., 255.254.255.0
133            if ((mask & 0x80000000) == 0) {
134                snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
135                return -1;
136            }
137            mask = mask << 1;
138        }
139        *prefixLength = p;
140    }
141    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns1", DHCP_PROP_NAME_PREFIX, p2p_interface);
142    property_get(prop_name, dns1, NULL);
143
144    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns2", DHCP_PROP_NAME_PREFIX, p2p_interface);
145    property_get(prop_name, dns2, NULL);
146
147    snprintf(prop_name, sizeof(prop_name), "%s.%s.leasetime", DHCP_PROP_NAME_PREFIX, p2p_interface);
148    if (property_get(prop_name, prop_value, NULL)) {
149        *lease = atol(prop_value);
150    }
151
152    snprintf(prop_name, sizeof(prop_name), "%s.%s.vendorInfo", DHCP_PROP_NAME_PREFIX,
153            p2p_interface);
154    property_get(prop_name, vendorInfo, NULL);
155
156    return 0;
157}
158
159static const char *ipaddr_to_string(in_addr_t addr)
160{
161    struct in_addr in_addr;
162
163    in_addr.s_addr = addr;
164    return inet_ntoa(in_addr);
165}
166
167/*
168 * Start the dhcp client daemon, and wait for it to finish
169 * configuring the interface.
170 *
171 * The device init.rc file needs a corresponding entry for this work.
172 *
173 * Example:
174 * service dhcpcd_<interface> /system/bin/dhcpcd -ABKL -f dhcpcd.conf
175 */
176int dhcp_do_request(const char *interface,
177                    char *ipaddr,
178                    char *gateway,
179                    uint32_t *prefixLength,
180                    char *dns1,
181                    char *dns2,
182                    char *server,
183                    uint32_t *lease,
184                    char *vendorInfo)
185{
186    char result_prop_name[PROPERTY_KEY_MAX];
187    char daemon_prop_name[PROPERTY_KEY_MAX];
188    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
189    char daemon_cmd[PROPERTY_VALUE_MAX * 2 + sizeof(DHCP_CONFIG_PATH)];
190    const char *ctrl_prop = "ctl.start";
191    const char *desired_status = "running";
192    /* Interface name after converting p2p0-p2p0-X to p2p to reuse system properties */
193    char p2p_interface[MAX_INTERFACE_LENGTH];
194
195    get_p2p_interface_replacement(interface, p2p_interface);
196
197    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
198            DHCP_PROP_NAME_PREFIX,
199            p2p_interface);
200
201    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
202            DAEMON_PROP_NAME,
203            p2p_interface);
204
205    /* Erase any previous setting of the dhcp result property */
206    property_set(result_prop_name, "");
207
208    /* Start the daemon and wait until it's ready */
209    if (property_get(HOSTNAME_PROP_NAME, prop_value, NULL) && (prop_value[0] != '\0'))
210        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:-f %s -h %s %s", DAEMON_NAME,
211                 p2p_interface, DHCP_CONFIG_PATH, prop_value, interface);
212    else
213        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:-f %s %s", DAEMON_NAME,
214                 DHCP_CONFIG_PATH, p2p_interface, interface);
215    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
216    property_set(ctrl_prop, daemon_cmd);
217    if (wait_for_property(daemon_prop_name, desired_status, 10) < 0) {
218        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
219        return -1;
220    }
221
222    /* Wait for the daemon to return a result */
223    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
224        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
225        return -1;
226    }
227
228    if (!property_get(result_prop_name, prop_value, NULL)) {
229        /* shouldn't ever happen, given the success of wait_for_property() */
230        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
231        return -1;
232    }
233    if (strcmp(prop_value, "ok") == 0) {
234        char dns_prop_name[PROPERTY_KEY_MAX];
235        if (fill_ip_info(interface, ipaddr, gateway, prefixLength,
236                dns1, dns2, server, lease, vendorInfo) == -1) {
237            return -1;
238        }
239
240        /* copy dns data to system properties - TODO - remove this after we have async
241         * notification of renewal's */
242        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns1", interface);
243        property_set(dns_prop_name, *dns1 ? ipaddr_to_string(*dns1) : "");
244        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns2", interface);
245        property_set(dns_prop_name, *dns2 ? ipaddr_to_string(*dns2) : "");
246        return 0;
247    } else {
248        snprintf(errmsg, sizeof(errmsg), "DHCP result was %s", prop_value);
249        return -1;
250    }
251}
252
253/**
254 * Stop the DHCP client daemon.
255 */
256int dhcp_stop(const char *interface)
257{
258    char result_prop_name[PROPERTY_KEY_MAX];
259    char daemon_prop_name[PROPERTY_KEY_MAX];
260    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
261    const char *ctrl_prop = "ctl.stop";
262    const char *desired_status = "stopped";
263
264    char p2p_interface[MAX_INTERFACE_LENGTH];
265
266    get_p2p_interface_replacement(interface, p2p_interface);
267
268    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
269            DHCP_PROP_NAME_PREFIX,
270            p2p_interface);
271
272    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
273            DAEMON_PROP_NAME,
274            p2p_interface);
275
276    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, p2p_interface);
277
278    /* Stop the daemon and wait until it's reported to be stopped */
279    property_set(ctrl_prop, daemon_cmd);
280    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
281        return -1;
282    }
283    property_set(result_prop_name, "failed");
284    return 0;
285}
286
287/**
288 * Release the current DHCP client lease.
289 */
290int dhcp_release_lease(const char *interface)
291{
292    char daemon_prop_name[PROPERTY_KEY_MAX];
293    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
294    const char *ctrl_prop = "ctl.stop";
295    const char *desired_status = "stopped";
296
297    char p2p_interface[MAX_INTERFACE_LENGTH];
298
299    get_p2p_interface_replacement(interface, p2p_interface);
300
301    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
302            DAEMON_PROP_NAME,
303            p2p_interface);
304
305    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, p2p_interface);
306
307    /* Stop the daemon and wait until it's reported to be stopped */
308    property_set(ctrl_prop, daemon_cmd);
309    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
310        return -1;
311    }
312    return 0;
313}
314
315char *dhcp_get_errmsg() {
316    return errmsg;
317}
318
319/**
320 * The device init.rc file needs a corresponding entry.
321 *
322 * Example:
323 * service iprenew_<interface> /system/bin/dhcpcd -n
324 *
325 */
326int dhcp_do_request_renew(const char *interface,
327                    char *ipaddr,
328                    char *gateway,
329                    uint32_t *prefixLength,
330                    char *dns1,
331                    char *dns2,
332                    char *server,
333                    uint32_t *lease,
334                    char *vendorInfo)
335{
336    char result_prop_name[PROPERTY_KEY_MAX];
337    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
338    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
339    const char *ctrl_prop = "ctl.start";
340
341    char p2p_interface[MAX_INTERFACE_LENGTH];
342
343    get_p2p_interface_replacement(interface, p2p_interface);
344
345    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
346            DHCP_PROP_NAME_PREFIX,
347            p2p_interface);
348
349    /* Erase any previous setting of the dhcp result property */
350    property_set(result_prop_name, "");
351
352    /* Start the renew daemon and wait until it's ready */
353    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:%s", DAEMON_NAME_RENEW,
354            p2p_interface, interface);
355    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
356    property_set(ctrl_prop, daemon_cmd);
357
358    /* Wait for the daemon to return a result */
359    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
360        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP Renew to finish");
361        return -1;
362    }
363
364    if (!property_get(result_prop_name, prop_value, NULL)) {
365        /* shouldn't ever happen, given the success of wait_for_property() */
366        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP Renew result property was not set");
367        return -1;
368    }
369    if (strcmp(prop_value, "ok") == 0) {
370        fill_ip_info(interface, ipaddr, gateway, prefixLength,
371                dns1, dns2, server, lease, vendorInfo);
372        return 0;
373    } else {
374        snprintf(errmsg, sizeof(errmsg), "DHCP Renew result was %s", prop_value);
375        return -1;
376    }
377}
378