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      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 
     28 static const char DAEMON_NAME[]        = "dhcpcd";
     29 static const char DAEMON_PROP_NAME[]   = "init.svc.dhcpcd";
     30 static const char HOSTNAME_PROP_NAME[] = "net.hostname";
     31 static const char DHCP_PROP_NAME_PREFIX[]  = "dhcp";
     32 static const int NAP_TIME = 200;   /* wait for 200ms at a time */
     33                                   /* when polling for property values */
     34 static const char DAEMON_NAME_RENEW[]  = "iprenew";
     35 static char errmsg[100];
     36 /* interface length for dhcpcd daemon start (dhcpcd_<interface> as defined in init.rc file)
     37  * or for filling up system properties dhcpcd.<interface>.ipaddress, dhcpcd.<interface>.dns1
     38  * and other properties on a successful bind
     39  */
     40 #define MAX_INTERFACE_LENGTH 25
     41 
     42 /*
     43  * P2p interface names increase sequentially p2p-p2p0-1, p2p-p2p0-2.. after
     44  * group formation. This does not work well with system properties which can quickly
     45  * exhaust or for specifiying a dhcp start target in init which requires
     46  * interface to be pre-defined in init.rc file.
     47  *
     48  * This function returns a common string p2p for all p2p interfaces.
     49  */
     50 void get_p2p_interface_replacement(const char *interface, char *p2p_interface) {
     51     /* Use p2p for any interface starting with p2p. */
     52     if (strncmp(interface, "p2p",3) == 0) {
     53         strncpy(p2p_interface, "p2p", MAX_INTERFACE_LENGTH);
     54     } else {
     55         strncpy(p2p_interface, interface, MAX_INTERFACE_LENGTH);
     56     }
     57 }
     58 
     59 /*
     60  * Wait for a system property to be assigned a specified value.
     61  * If desired_value is NULL, then just wait for the property to
     62  * be created with any value. maxwait is the maximum amount of
     63  * time in seconds to wait before giving up.
     64  */
     65 static int wait_for_property(const char *name, const char *desired_value, int maxwait)
     66 {
     67     char value[PROPERTY_VALUE_MAX] = {'\0'};
     68     int maxnaps = (maxwait * 1000) / NAP_TIME;
     69 
     70     if (maxnaps < 1) {
     71         maxnaps = 1;
     72     }
     73 
     74     while (maxnaps-- > 0) {
     75         usleep(NAP_TIME * 1000);
     76         if (property_get(name, value, NULL)) {
     77             if (desired_value == NULL ||
     78                     strcmp(value, desired_value) == 0) {
     79                 return 0;
     80             }
     81         }
     82     }
     83     return -1; /* failure */
     84 }
     85 
     86 static int fill_ip_info(const char *interface,
     87                      char *ipaddr,
     88                      char *gateway,
     89                      uint32_t *prefixLength,
     90                      char *dns1,
     91                      char *dns2,
     92                      char *server,
     93                      uint32_t *lease,
     94                      char *vendorInfo)
     95 {
     96     char prop_name[PROPERTY_KEY_MAX];
     97     char prop_value[PROPERTY_VALUE_MAX];
     98     /* Interface name after converting p2p0-p2p0-X to p2p to reuse system properties */
     99     char p2p_interface[MAX_INTERFACE_LENGTH];
    100 
    101     get_p2p_interface_replacement(interface, p2p_interface);
    102 
    103     snprintf(prop_name, sizeof(prop_name), "%s.%s.ipaddress", DHCP_PROP_NAME_PREFIX, p2p_interface);
    104     property_get(prop_name, ipaddr, NULL);
    105 
    106     snprintf(prop_name, sizeof(prop_name), "%s.%s.gateway", DHCP_PROP_NAME_PREFIX, p2p_interface);
    107     property_get(prop_name, gateway, NULL);
    108 
    109     snprintf(prop_name, sizeof(prop_name), "%s.%s.server", DHCP_PROP_NAME_PREFIX, p2p_interface);
    110     property_get(prop_name, server, NULL);
    111 
    112     //TODO: Handle IPv6 when we change system property usage
    113     if (strcmp(gateway, "0.0.0.0") == 0) {
    114         //DHCP server is our best bet as gateway
    115         strncpy(gateway, server, PROPERTY_VALUE_MAX);
    116     }
    117 
    118     snprintf(prop_name, sizeof(prop_name), "%s.%s.mask", DHCP_PROP_NAME_PREFIX, p2p_interface);
    119     if (property_get(prop_name, prop_value, NULL)) {
    120         int p;
    121         // this conversion is v4 only, but this dhcp client is v4 only anyway
    122         in_addr_t mask = ntohl(inet_addr(prop_value));
    123         // Check netmask is a valid IP address.  ntohl gives NONE response (all 1's) for
    124         // non 255.255.255.255 inputs.  if we get that value check if it is legit..
    125         if (mask == INADDR_NONE && strcmp(prop_value, "255.255.255.255") != 0) {
    126             snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
    127             return -1;
    128         }
    129         for (p = 0; p < 32; p++) {
    130             if (mask == 0) break;
    131             // check for non-contiguous netmask, e.g., 255.254.255.0
    132             if ((mask & 0x80000000) == 0) {
    133                 snprintf(errmsg, sizeof(errmsg), "DHCP gave invalid net mask %s", prop_value);
    134                 return -1;
    135             }
    136             mask = mask << 1;
    137         }
    138         *prefixLength = p;
    139     }
    140     snprintf(prop_name, sizeof(prop_name), "%s.%s.dns1", DHCP_PROP_NAME_PREFIX, p2p_interface);
    141     property_get(prop_name, dns1, NULL);
    142 
    143     snprintf(prop_name, sizeof(prop_name), "%s.%s.dns2", DHCP_PROP_NAME_PREFIX, p2p_interface);
    144     property_get(prop_name, dns2, NULL);
    145 
    146     snprintf(prop_name, sizeof(prop_name), "%s.%s.leasetime", DHCP_PROP_NAME_PREFIX, p2p_interface);
    147     if (property_get(prop_name, prop_value, NULL)) {
    148         *lease = atol(prop_value);
    149     }
    150 
    151     snprintf(prop_name, sizeof(prop_name), "%s.%s.vendorInfo", DHCP_PROP_NAME_PREFIX,
    152             p2p_interface);
    153     property_get(prop_name, vendorInfo, NULL);
    154 
    155     return 0;
    156 }
    157 
    158 static const char *ipaddr_to_string(in_addr_t addr)
    159 {
    160     struct in_addr in_addr;
    161 
    162     in_addr.s_addr = addr;
    163     return inet_ntoa(in_addr);
    164 }
    165 
    166 /*
    167  * Start the dhcp client daemon, and wait for it to finish
    168  * configuring the interface.
    169  *
    170  * The device init.rc file needs a corresponding entry for this work.
    171  *
    172  * Example:
    173  * service dhcpcd_<interface> /system/bin/dhcpcd -ABKL
    174  */
    175 int dhcp_do_request(const char *interface,
    176                     char *ipaddr,
    177                     char *gateway,
    178                     uint32_t *prefixLength,
    179                     char *dns1,
    180                     char *dns2,
    181                     char *server,
    182                     uint32_t *lease,
    183                     char *vendorInfo)
    184 {
    185     char result_prop_name[PROPERTY_KEY_MAX];
    186     char daemon_prop_name[PROPERTY_KEY_MAX];
    187     char prop_value[PROPERTY_VALUE_MAX] = {'\0'};
    188     char daemon_cmd[PROPERTY_VALUE_MAX * 2];
    189     const char *ctrl_prop = "ctl.start";
    190     const char *desired_status = "running";
    191     /* Interface name after converting p2p0-p2p0-X to p2p to reuse system properties */
    192     char p2p_interface[MAX_INTERFACE_LENGTH];
    193 
    194     get_p2p_interface_replacement(interface, p2p_interface);
    195 
    196     snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result",
    197             DHCP_PROP_NAME_PREFIX,
    198             p2p_interface);
    199 
    200     snprintf(daemon_prop_name, sizeof(daemon_prop_name), "%s_%s",
    201             DAEMON_PROP_NAME,
    202             p2p_interface);
    203 
    204     /* Erase any previous setting of the dhcp result property */
    205     property_set(result_prop_name, "");
    206 
    207     /* Start the daemon and wait until it's ready */
    208     if (property_get(HOSTNAME_PROP_NAME, prop_value, NULL) && (prop_value[0] != '\0'))
    209         snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:-h %s %s", DAEMON_NAME, p2p_interface,
    210                  prop_value, interface);
    211     else
    212         snprintf(daemon_cmd, sizeof(daemon_cmd), "%s_%s:%s", DAEMON_NAME, p2p_interface, interface);
    213     memset(prop_value, '\0', PROPERTY_VALUE_MAX);
    214     property_set(ctrl_prop, daemon_cmd);
    215     if (wait_for_property(daemon_prop_name, desired_status, 10) < 0) {
    216         snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for dhcpcd to start");
    217         return -1;
    218     }
    219 
    220     /* Wait for the daemon to return a result */
    221     if (wait_for_property(result_prop_name, NULL, 30) < 0) {
    222         snprintf(errmsg, sizeof(errmsg), "%s", "Timed out waiting for DHCP to finish");
    223         return -1;
    224     }
    225 
    226     if (!property_get(result_prop_name, prop_value, NULL)) {
    227         /* shouldn't ever happen, given the success of wait_for_property() */
    228         snprintf(errmsg, sizeof(errmsg), "%s", "DHCP result property was not set");
    229         return -1;
    230     }
    231     if (strcmp(prop_value, "ok") == 0) {
    232         char dns_prop_name[PROPERTY_KEY_MAX];
    233         if (fill_ip_info(interface, ipaddr, gateway, prefixLength,
    234                 dns1, dns2, server, lease, vendorInfo) == -1) {
    235             return -1;
    236         }
    237 
    238         /* copy dns data to system properties - TODO - remove this after we have async
    239          * notification of renewal's */
    240         snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns1", interface);
    241         property_set(dns_prop_name, *dns1 ? ipaddr_to_string(*dns1) : "");
    242         snprintf(dns_prop_name, sizeof(dns_prop_name), "net.%s.dns2", interface);
    243         property_set(dns_prop_name, *dns2 ? ipaddr_to_string(*dns2) : "");
    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  */
    254 int 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  */
    288 int 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 
    313 char *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  */
    324 int dhcp_do_request_renew(const char *interface,
    325                     char *ipaddr,
    326                     char *gateway,
    327                     uint32_t *prefixLength,
    328                     char *dns1,
    329                     char *dns2,
    330                     char *server,
    331                     uint32_t *lease,
    332                     char *vendorInfo)
    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,
    369                 dns1, dns2, server, lease, vendorInfo);
    370         return 0;
    371     } else {
    372         snprintf(errmsg, sizeof(errmsg), "DHCP Renew result was %s", prop_value);
    373         return -1;
    374     }
    375 }
    376