dhcp_utils.c revision 8c85a00db6da092ec3766facd49132fa4fc319a1 
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 HOSTNAME_PROP_NAME[] = "net.hostname";
30static const char DHCP_PROP_NAME_PREFIX[]  = "dhcp";
31static const int  NAP_TIME = 1;   /* wait for 1 second at a time */
32                                  /* when polling for property values */
33static char errmsg[100];
34
35/*
36 * Wait for a system property to be assigned a specified value.
37 * If desired_value is NULL, then just wait for the property to
38 * be created with any value. maxwait is the maximum amount of
39 * time in seconds to wait before giving up.
40 */
41static int wait_for_property(const char *name, const char *desired_value, int maxwait)
42{
43    char value[PROPERTY_VALUE_MAX] = {'\0'};
44    int maxnaps = maxwait / NAP_TIME;
45
46    if (maxnaps < 1) {
47        maxnaps = 1;
48    }
49
50    while (maxnaps-- > 0) {
51        usleep(1000000);
52        if (property_get(name, value, NULL)) {
53            if (desired_value == NULL ||
54                    strcmp(value, desired_value) == 0) {
55                return 0;
56            }
57        }
58    }
59    return -1; /* failure */
60}
61
62static void fill_ip_info(const char *interface,
63                     in_addr_t *ipaddr,
64                     in_addr_t *gateway,
65                     in_addr_t *mask,
66                     in_addr_t *dns1,
67                     in_addr_t *dns2,
68                     in_addr_t *server,
69                     uint32_t  *lease)
70{
71    char prop_name[PROPERTY_KEY_MAX];
72    char prop_value[PROPERTY_VALUE_MAX];
73    struct in_addr addr;
74    in_addr_t iaddr;
75
76    snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, interface);
77    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
78        *ipaddr = addr.s_addr;
79    } else {
80        *ipaddr = 0;
81    }
82    snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, interface);
83    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
84        *gateway = addr.s_addr;
85    } else {
86        *gateway = 0;
87    }
88    snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, interface);
89    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
90        *mask = addr.s_addr;
91    } else {
92        *mask = 0;
93    }
94    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns1", DHCP_PROP_NAME_PREFIX, interface);
95    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
96        *dns1 = addr.s_addr;
97    } else {
98        *dns1 = 0;
99    }
100    snprintf(prop_name, sizeof(prop_name), "%s.%s.dns2", DHCP_PROP_NAME_PREFIX, interface);
101    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
102        *dns2 = addr.s_addr;
103    } else {
104        *dns2 = 0;
105    }
106    snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, interface);
107    if (property_get(prop_name, prop_value, NULL) && inet_aton(prop_value, &addr)) {
108        *server = addr.s_addr;
109    } else {
110        *server = 0;
111    }
112    snprintf(prop_name, sizeof(prop_name), "%s.%s.leasetime", DHCP_PROP_NAME_PREFIX, interface);
113    if (property_get(prop_name, prop_value, NULL)) {
114        *lease = atol(prop_value);
115    }
116}
117
118static const char *ipaddr_to_string(in_addr_t addr)
119{
120    struct in_addr in_addr;
121
122    in_addr.s_addr = addr;
123    return inet_ntoa(in_addr);
124}
125
126/*
127 * Start the dhcp client daemon, and wait for it to finish
128 * configuring the interface.
129 */
130int dhcp_do_request(const char *interface,
131                    in_addr_t *ipaddr,
132                    in_addr_t *gateway,
133                    in_addr_t *mask,
134                    in_addr_t *dns1,
135                    in_addr_t *dns2,
136                    in_addr_t *server,
137                    uint32_t  *lease)
138{
139    char result_prop_name[PROPERTY_KEY_MAX];
140    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
141    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
142    const char *ctrl_prop = "ctl.start";
143    const char *desired_status = "running";
144
145    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
146            DHCP_PROP_NAME_PREFIX,
147            interface);
148    /* Erase any previous setting of the dhcp result property */
149    property_set(result_prop_name, "");
150
151    /* Start the daemon and wait until it's ready */
152    if (property_get(HOSTNAME_PROP_NAME, prop_value, NULL) && (prop_value[0] != '\0'))
153        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s:-h %s %s", DAEMON_NAME,
154                 prop_value, interface);
155    else
156        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s:%s", DAEMON_NAME, interface);
157    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
158    property_set(ctrl_prop, daemon_cmd);
159    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 10) < 0) {
160        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
161        return -1;
162    }
163
164    /* Wait for the daemon to return a result */
165    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
166        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
167        return -1;
168    }
169
170    if (!property_get(result_prop_name, prop_value, NULL)) {
171        /* shouldn't ever happen, given the success of wait_for_property() */
172        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
173        return -1;
174    }
175    if (strcmp(prop_value, "ok") == 0) {
176        char dns_prop_name[PROPERTY_KEY_MAX];
177        fill_ip_info(interface, ipaddr, gateway, mask, dns1, dns2, server, lease);
178        /* copy the dhcp.XXX.dns properties to net.XXX.dns */
179        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns1", interface);
180        property_set(dns_prop_name, *dns1 ? ipaddr_to_string(*dns1) : "");
181        snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns2", interface);
182        property_set(dns_prop_name, *dns2 ? ipaddr_to_string(*dns2) : "");
183        return 0;
184    } else {
185        snprintf(errmsg, sizeof(errmsg), "DHCP result was %s", prop_value);
186        return -1;
187    }
188}
189
190/**
191 * Stop the DHCP client daemon.
192 */
193int dhcp_stop(const char *interface)
194{
195    char result_prop_name[PROPERTY_KEY_MAX];
196    const char *ctrl_prop = "ctl.stop";
197    const char *desired_status = "stopped";
198
199    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
200            DHCP_PROP_NAME_PREFIX,
201            interface);
202    /* Stop the daemon and wait until it's reported to be stopped */
203    property_set(ctrl_prop, DAEMON_NAME);
204    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) {
205        return -1;
206    }
207    property_set(result_prop_name, "failed");
208    return 0;
209}
210
211/**
212 * Release the current DHCP client lease.
213 */
214int dhcp_release_lease(const char *interface)
215{
216    const char *ctrl_prop = "ctl.stop";
217    const char *desired_status = "stopped";
218
219    /* Stop the daemon and wait until it's reported to be stopped */
220    property_set(ctrl_prop, DAEMON_NAME);
221    if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) {
222        return -1;
223    }
224    return 0;
225}
226
227char *dhcp_get_errmsg() {
228    return errmsg;
229}
230