dhcp_utils.c revision b1723b68921512f26562384898b9600f8f11d25e 
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 char errmsg[100];
35
36/*
37 * Wait for a system property to be assigned a specified value.
38 * If desired_value is NULL, then just wait for the property to
39 * be created with any value. maxwait is the maximum amount of
40 * time in seconds to wait before giving up.
41 */
42static int wait_for_property(const char *name, const char *desired_value, int maxwait)
43{
44    char value[PROPERTY_VALUE_MAX] = {'\0'};
45    int maxnaps = (maxwait * 1000) / NAP_TIME;
46
47    if (maxnaps < 1) {
48        maxnaps = 1;
49    }
50
51    while (maxnaps-- > 0) {
52        usleep(NAP_TIME * 1000);
53        if (property_get(name, value, NULL)) {
54            if (desired_value == NULL ||
55                    strcmp(value, desired_value) == 0) {
56                return 0;
57            }
58        }
59    }
60    return -1; /* failure */
61}
62
63static void fill_ip_info(const char *interface,
64                     in_addr_t *ipaddr,
65                     in_addr_t *gateway,
66                     in_addr_t *mask,
67                     in_addr_t *dns1,
68                     in_addr_t *dns2,
69                     in_addr_t *server,
70                     uint32_t  *lease)
71{
72    char prop_name[PROPERTY_KEY_MAX];
73    char prop_value[PROPERTY_VALUE_MAX];
74    struct in_addr addr;
75    in_addr_t iaddr;
76
77    snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, interface);
78    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
79        *ipaddr = addr.s_addr;
80    } else {
81        *ipaddr = 0;
82    }
83    snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, interface);
84    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
85        *gateway = addr.s_addr;
86    } else {
87        *gateway = 0;
88    }
89    snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, interface);
90    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
91        *mask = addr.s_addr;
92    } else {
93        *mask = 0;
94    }
95    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns1", DHCP_PROP_NAME_PREFIX, interface);
96    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
97        *dns1 = addr.s_addr;
98    } else {
99        *dns1 = 0;
100    }
101    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns2", DHCP_PROP_NAME_PREFIX, interface);
102    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
103        *dns2 = addr.s_addr;
104    } else {
105        *dns2 = 0;
106    }
107    snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, interface);
108    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
109        *server = addr.s_addr;
110    } else {
111        *server = 0;
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}
118
119static const char *ipaddr_to_string(in_addr_t addr)
120{
121    struct in_addr in_addr;
122
123    in_addr.s_addr = addr;
124    return inet_ntoa(in_addr);
125}
126
127/*
128 * Start the dhcp client daemon, and wait for it to finish
129 * configuring the interface.
130 */
131int dhcp_do_request(const char *interface,
132                    in_addr_t *ipaddr,
133                    in_addr_t *gateway,
134                    in_addr_t *mask,
135                    in_addr_t *dns1,
136                    in_addr_t *dns2,
137                    in_addr_t *server,
138                    uint32_t  *lease)
139{
140    char result_prop_name[PROPERTY_KEY_MAX];
141    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
142    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
143    const char *ctrl_prop = "ctl.start";
144    const char *desired_status = "running";
145
146    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
147            DHCP_PROP_NAME_PREFIX,
148            interface);
149    /* Erase any previous setting of the dhcp result property */
150    property_set(result_prop_name, "");
151
152    /* Start the daemon and wait until it's ready */
153    if (property_get(HOSTNAME_PROP_NAME, prop_value, NULL) && (prop_value[0] != '\0'))
154        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s:-h %s %s", DAEMON_NAME,
155                 prop_value, interface);
156    else
157        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s:%s", DAEMON_NAME, interface);
158    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
159    property_set(ctrl_prop, daemon_cmd);
160    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 10) < 0) {
161        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
162        return -1;
163    }
164
165    /* Wait for the daemon to return a result */
166    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
167        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
168        return -1;
169    }
170
171    if (!property_get(result_prop_name, prop_value, NULL)) {
172        /* shouldn't ever happen, given the success of wait_for_property() */
173        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
174        return -1;
175    }
176    if (strcmp(prop_value, "ok") == 0) {
177        char dns_prop_name[PROPERTY_KEY_MAX];
178        fill_ip_info(interface, ipaddr, gateway, mask, dns1, dns2, server, lease);
179        /* copy the dhcp.XXX.dns properties to net.XXX.dns */
180        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns1", interface);
181        property_set(dns_prop_name, *dns1 ? ipaddr_to_string(*dns1) : "");
182        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns2", interface);
183        property_set(dns_prop_name, *dns2 ? ipaddr_to_string(*dns2) : "");
184        return 0;
185    } else {
186        snprintf(errmsg, sizeof(errmsg), "DHCP result was %s", prop_value);
187        return -1;
188    }
189}
190
191/**
192 * Stop the DHCP client daemon.
193 */
194int dhcp_stop(const char *interface)
195{
196    char result_prop_name[PROPERTY_KEY_MAX];
197    const char *ctrl_prop = "ctl.stop";
198    const char *desired_status = "stopped";
199
200    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
201            DHCP_PROP_NAME_PREFIX,
202            interface);
203    /* Stop the daemon and wait until it's reported to be stopped */
204    property_set(ctrl_prop, DAEMON_NAME);
205    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) {
206        return -1;
207    }
208    property_set(result_prop_name, "failed");
209    return 0;
210}
211
212/**
213 * Release the current DHCP client lease.
214 */
215int dhcp_release_lease(const char *interface)
216{
217    const char *ctrl_prop = "ctl.stop";
218    const char *desired_status = "stopped";
219
220    /* Stop the daemon and wait until it's reported to be stopped */
221    property_set(ctrl_prop, DAEMON_NAME);
222    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) {
223        return -1;
224    }
225    return 0;
226}
227
228char *dhcp_get_errmsg() {
229    return errmsg;
230}
231