dhcp_utils.c revision 35237d135807af84bf9b0e5b8d7f8633e58db6f5 
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 <unistd.h>
22#include <arpa/inet.h>
23#include <netinet/in.h>
24
25#include <cutils/properties.h>
26
27static const char DAEMON_NAME[]       = "dhcpcd";
28static const char DAEMON_PROP_NAME[]  = "init.svc.dhcpcd";
29static const char DHCP_PROP_NAME_PREFIX[]  = "dhcp";
30static const int  NAP_TIME = 1;   /* wait for 1 second at a time */
31                                  /* when polling for property values */
32static char errmsg[100];
33
34/*
35 * Wait for a system property to be assigned a specified value.
36 * If desired_value is NULL, then just wait for the property to
37 * be created with any value. maxwait is the maximum amount of
38 * time in seconds to wait before giving up.
39 */
40static int wait_for_property(const char *name, const char *desired_value, int maxwait)
41{
42    char value[PROPERTY_VALUE_MAX] = {'\0'};
43    int maxnaps = maxwait / NAP_TIME;
44
45    if (maxnaps < 1) {
46        maxnaps = 1;
47    }
48
49    while (maxnaps-- > 0) {
50        usleep(1000000);
51        if (property_get(name, value, NULL)) {
52            if (desired_value == NULL ||
53                    strcmp(value, desired_value) == 0) {
54                return 0;
55            }
56        }
57    }
58    return -1; /* failure */
59}
60
61static void fill_ip_info(const char *interface,
62                     in_addr_t *ipaddr,
63                     in_addr_t *gateway,
64                     in_addr_t *mask,
65                     in_addr_t *dns1,
66                     in_addr_t *dns2,
67                     in_addr_t *server,
68                     uint32_t  *lease)
69{
70    char prop_name[PROPERTY_KEY_MAX];
71    char prop_value[PROPERTY_VALUE_MAX];
72    struct in_addr addr;
73    in_addr_t iaddr;
74
75    snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, interface);
76    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
77        *ipaddr = addr.s_addr;
78    } else {
79        *ipaddr = 0;
80    }
81    snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, interface);
82    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
83        *gateway = addr.s_addr;
84    } else {
85        *gateway = 0;
86    }
87    snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, interface);
88    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
89        *mask = addr.s_addr;
90    } else {
91        *mask = 0;
92    }
93    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns1", DHCP_PROP_NAME_PREFIX, interface);
94    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
95        *dns1 = addr.s_addr;
96    } else {
97        *dns1 = 0;
98    }
99    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns2", DHCP_PROP_NAME_PREFIX, interface);
100    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
101        *dns2 = addr.s_addr;
102    } else {
103        *dns2 = 0;
104    }
105    snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, interface);
106    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
107        *server = addr.s_addr;
108    } else {
109        *server = 0;
110    }
111    snprintf(prop_name, sizeof(prop_name), "%s.%s.leasetime", DHCP_PROP_NAME_PREFIX, interface);
112    if (property_get(prop_name, prop_value, NULL)) {
113        *lease = atol(prop_value);
114    }
115}
116
117/*
118 * Start the dhcp client daemon, and wait for it to finish
119 * configuring the interface.
120 */
121int dhcp_do_request(const char *interface,
122                    in_addr_t *ipaddr,
123                    in_addr_t *gateway,
124                    in_addr_t *mask,
125                    in_addr_t *dns1,
126                    in_addr_t *dns2,
127                    in_addr_t *server,
128                    uint32_t  *lease)
129{
130    char result_prop_name[PROPERTY_KEY_MAX];
131    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
132    const char *ctrl_prop = "ctl.start";
133    const char *desired_status = "running";
134
135    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
136            DHCP_PROP_NAME_PREFIX,
137            interface);
138    /* Erase any previous setting of the dhcp result property */
139    property_set(result_prop_name, "");
140
141    /* Start the daemon and wait until it's ready */
142    property_set(ctrl_prop, DAEMON_NAME);
143    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 10) < 0) {
144        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
145        return -1;
146    }
147
148    /* Wait for the daemon to return a result */
149    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
150        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
151        return -1;
152    }
153
154    if (!property_get(result_prop_name, prop_value, NULL)) {
155        /* shouldn't ever happen, given the success of wait_for_property() */
156        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
157        return -1;
158    }
159    if (strcmp(prop_value, "ok") == 0) {
160        fill_ip_info(interface, ipaddr, gateway, mask, dns1, dns2, server, lease);
161        return 0;
162    } else {
163        snprintf(errmsg, sizeof(errmsg), "DHCP result was %s", prop_value);
164        return -1;
165    }
166}
167
168/**
169 * Stop the DHCP client daemon.
170 */
171int dhcp_stop(const char *interface)
172{
173    const char *ctrl_prop = "ctl.stop";
174    const char *desired_status = "stopped";
175
176    /* Stop the daemon and wait until it's reported to be stopped */
177    property_set(ctrl_prop, DAEMON_NAME);
178    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) {
179        return -1;
180    }
181    return 0;
182}
183
184/**
185 * Release the current DHCP client lease.
186 */
187int dhcp_release_lease(const char *interface)
188{
189    const char *ctrl_prop = "ctl.stop";
190    const char *desired_status = "stopped";
191
192    /* Stop the daemon and wait until it's reported to be stopped */
193    property_set(ctrl_prop, DAEMON_NAME);
194    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) {
195        return -1;
196    }
197    return 0;
198}
199
200char *dhcp_get_errmsg() {
201    return errmsg;
202}
203