dhcp_utils.c revision dd7bc3319deb2b77c5d07a51b7d6cd7e11b5beb0
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 char result_prop_name[PROPERTY_KEY_MAX]; 174 const char *ctrl_prop = "ctl.stop"; 175 const char *desired_status = "stopped"; 176 177 snprintf(result_prop_name, sizeof(result_prop_name), "%s.%s.result", 178 DHCP_PROP_NAME_PREFIX, 179 interface); 180 /* Stop the daemon and wait until it's reported to be stopped */ 181 property_set(ctrl_prop, DAEMON_NAME); 182 if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) { 183 return -1; 184 } 185 property_set(result_prop_name, "failed"); 186 return 0; 187} 188 189/** 190 * Release the current DHCP client lease. 191 */ 192int dhcp_release_lease(const char *interface) 193{ 194 const char *ctrl_prop = "ctl.stop"; 195 const char *desired_status = "stopped"; 196 197 /* Stop the daemon and wait until it's reported to be stopped */ 198 property_set(ctrl_prop, DAEMON_NAME); 199 if (wait_for_property(DAEMON_PROP_NAME, desired_status, 5) < 0) { 200 return -1; 201 } 202 return 0; 203} 204 205char *dhcp_get_errmsg() { 206 return errmsg; 207} 208