dhcp_utils.c revision fdd573188d08fbd3739aeda19ef0f2d03752db9f 
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 *dns[],
92                     char *server,
93                     uint32_t *lease,
94                     char *vendorInfo,
95                     char *domain)
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    int x;
102
103    get_p2p_interface_replacement(interface, p2p_interface);
104
105    snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, p2p_interface);
106    property_get(prop_name, ipaddr, NULL);
107
108    snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, p2p_interface);
109    property_get(prop_name, gateway, NULL);
110
111    snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, p2p_interface);
112    property_get(prop_name, server, NULL);
113
114    //TODO: Handle IPv6 when we change system property usage
115    if (gateway[0] == '\0' || strncmp(gateway, "0.0.0.0", 7) == 0) {
116        //DHCP server is our best bet as gateway
117        strncpy(gateway, server, PROPERTY_VALUE_MAX);
118    }
119
120    snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, p2p_interface);
121    if (property_get(prop_name, prop_value, NULL)) {
122        int p;
123        // this conversion is v4 only, but this dhcp client is v4 only anyway
124        in_addr_t mask = ntohl(inet_addr(prop_value));
125        // Check netmask is a valid IP address.  ntohl gives NONE response (all 1's) for
126        // non 255.255.255.255 inputs.  if we get that value check if it is legit..
127        if (mask == INADDR_NONE && strcmp(prop_value, "255.255.255.255") != 0) {
128            snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
129            return -1;
130        }
131        for (p = 0; p < 32; p++) {
132            if (mask == 0) break;
133            // check for non-contiguous netmask, e.g., 255.254.255.0
134            if ((mask & 0x80000000) == 0) {
135                snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
136                return -1;
137            }
138            mask = mask << 1;
139        }
140        *prefixLength = p;
141    }
142
143    for (x=0; dns[x] != NULL; x++) {
144        snprintf(prop_name, sizeof(prop_name), "%s.%s.dns%d", DHCP_PROP_NAME_PREFIX, p2p_interface, x+1);
145        property_get(prop_name, dns[x], NULL);
146    }
147
148    snprintf(prop_name, sizeof(prop_name), "%s.%s.leasetime", DHCP_PROP_NAME_PREFIX, p2p_interface);
149    if (property_get(prop_name, prop_value, NULL)) {
150        *lease = atol(prop_value);
151    }
152
153    snprintf(prop_name, sizeof(prop_name), "%s.%s.vendorInfo", DHCP_PROP_NAME_PREFIX,
154            p2p_interface);
155    property_get(prop_name, vendorInfo, NULL);
156
157    snprintf(prop_name, sizeof(prop_name), "%s.%s.domain", DHCP_PROP_NAME_PREFIX,
158            p2p_interface);
159    property_get(prop_name, domain, NULL);
160
161    return 0;
162}
163
164static const char *ipaddr_to_string(in_addr_t addr)
165{
166    struct in_addr in_addr;
167
168    in_addr.s_addr = addr;
169    return inet_ntoa(in_addr);
170}
171
172/*
173 * Start the dhcp client daemon, and wait for it to finish
174 * configuring the interface.
175 *
176 * The device init.rc file needs a corresponding entry for this work.
177 *
178 * Example:
179 * service dhcpcd_<interface> /system/bin/dhcpcd -ABKL -f dhcpcd.conf
180 */
181int dhcp_do_request(const char *interface,
182                    char *ipaddr,
183                    char *gateway,
184                    uint32_t *prefixLength,
185                    char *dns[],
186                    char *server,
187                    uint32_t *lease,
188                    char *vendorInfo,
189                    char *domain)
190{
191    char result_prop_name[PROPERTY_KEY_MAX];
192    char daemon_prop_name[PROPERTY_KEY_MAX];
193    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
194    char daemon_cmd[PROPERTY_VALUE_MAX * 2 + sizeof(DHCP_CONFIG_PATH)];
195    const char *ctrl_prop = "ctl.start";
196    const char *desired_status = "running";
197    /* Interface name after converting p2p0-p2p0-X to p2p to reuse system properties */
198    char p2p_interface[MAX_INTERFACE_LENGTH];
199
200    get_p2p_interface_replacement(interface, p2p_interface);
201
202    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
203            DHCP_PROP_NAME_PREFIX,
204            p2p_interface);
205
206    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
207            DAEMON_PROP_NAME,
208            p2p_interface);
209
210    /* Erase any previous setting of the dhcp result property */
211    property_set(result_prop_name, "");
212
213    /* Start the daemon and wait until it's ready */
214    if (property_get(HOSTNAME_PROP_NAME, prop_value, NULL) && (prop_value[0] != '\0'))
215        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:-f %s -h %s %s", DAEMON_NAME,
216                 p2p_interface, DHCP_CONFIG_PATH, prop_value, interface);
217    else
218        snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:-f %s %s", DAEMON_NAME,
219                 DHCP_CONFIG_PATH, p2p_interface, interface);
220    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
221    property_set(ctrl_prop, daemon_cmd);
222    if (wait_for_property(daemon_prop_name, desired_status, 10) < 0) {
223        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
224        return -1;
225    }
226
227    /* Wait for the daemon to return a result */
228    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
229        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
230        return -1;
231    }
232
233    if (!property_get(result_prop_name, prop_value, NULL)) {
234        /* shouldn't ever happen, given the success of wait_for_property() */
235        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
236        return -1;
237    }
238    if (strcmp(prop_value, "ok") == 0) {
239        char dns_prop_name[PROPERTY_KEY_MAX];
240        if (fill_ip_info(interface, ipaddr, gateway, prefixLength, dns,
241                server, lease, vendorInfo, domain) == -1) {
242            return -1;
243        }
244        return 0;
245    } else {
246        snprintf(errmsg, sizeof(errmsg), "DHCP result was %s", prop_value);
247        return -1;
248    }
249}
250
251/**
252 * Stop the DHCP client daemon.
253 */
254int dhcp_stop(const char *interface)
255{
256    char result_prop_name[PROPERTY_KEY_MAX];
257    char daemon_prop_name[PROPERTY_KEY_MAX];
258    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
259    const char *ctrl_prop = "ctl.stop";
260    const char *desired_status = "stopped";
261
262    char p2p_interface[MAX_INTERFACE_LENGTH];
263
264    get_p2p_interface_replacement(interface, p2p_interface);
265
266    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
267            DHCP_PROP_NAME_PREFIX,
268            p2p_interface);
269
270    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
271            DAEMON_PROP_NAME,
272            p2p_interface);
273
274    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, p2p_interface);
275
276    /* Stop the daemon and wait until it's reported to be stopped */
277    property_set(ctrl_prop, daemon_cmd);
278    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
279        return -1;
280    }
281    property_set(result_prop_name, "failed");
282    return 0;
283}
284
285/**
286 * Release the current DHCP client lease.
287 */
288int dhcp_release_lease(const char *interface)
289{
290    char daemon_prop_name[PROPERTY_KEY_MAX];
291    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
292    const char *ctrl_prop = "ctl.stop";
293    const char *desired_status = "stopped";
294
295    char p2p_interface[MAX_INTERFACE_LENGTH];
296
297    get_p2p_interface_replacement(interface, p2p_interface);
298
299    snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
300            DAEMON_PROP_NAME,
301            p2p_interface);
302
303    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s", DAEMON_NAME, p2p_interface);
304
305    /* Stop the daemon and wait until it's reported to be stopped */
306    property_set(ctrl_prop, daemon_cmd);
307    if (wait_for_property(daemon_prop_name, desired_status, 5) < 0) {
308        return -1;
309    }
310    return 0;
311}
312
313char *dhcp_get_errmsg() {
314    return errmsg;
315}
316
317/**
318 * The device init.rc file needs a corresponding entry.
319 *
320 * Example:
321 * service iprenew_<interface> /system/bin/dhcpcd -n
322 *
323 */
324int dhcp_do_request_renew(const char *interface,
325                    char *ipaddr,
326                    char *gateway,
327                    uint32_t *prefixLength,
328                    char *dns[],
329                    char *server,
330                    uint32_t *lease,
331                    char *vendorInfo,
332                    char *domain)
333{
334    char result_prop_name[PROPERTY_KEY_MAX];
335    char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
336    char daemon_cmd[PROPERTY_VALUE_MAX * 2];
337    const char *ctrl_prop = "ctl.start";
338
339    char p2p_interface[MAX_INTERFACE_LENGTH];
340
341    get_p2p_interface_replacement(interface, p2p_interface);
342
343    snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
344            DHCP_PROP_NAME_PREFIX,
345            p2p_interface);
346
347    /* Erase any previous setting of the dhcp result property */
348    property_set(result_prop_name, "");
349
350    /* Start the renew daemon and wait until it's ready */
351    snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:%s", DAEMON_NAME_RENEW,
352            p2p_interface, interface);
353    memset(prop_value, '\0', PROPERTY_VALUE_MAX);
354    property_set(ctrl_prop, daemon_cmd);
355
356    /* Wait for the daemon to return a result */
357    if (wait_for_property(result_prop_name, NULL, 30) < 0) {
358        snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP Renew to finish");
359        return -1;
360    }
361
362    if (!property_get(result_prop_name, prop_value, NULL)) {
363        /* shouldn't ever happen, given the success of wait_for_property() */
364        snprintf(errmsg, sizeof(errmsg), "%s", "DHCP Renew result property was not set");
365        return -1;
366    }
367    if (strcmp(prop_value, "ok") == 0) {
368        fill_ip_info(interface, ipaddr, gateway, prefixLength, dns,
369                server, lease, vendorInfo, domain);
370        return 0;
371    } else {
372        snprintf(errmsg, sizeof(errmsg), "DHCP Renew result was %s", prop_value);
373        return -1;
374    }
375}
376