1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <errno.h> 4 #include <fcntl.h> 5 6 #include "dhcp.h" 7 #include "config.h" 8 9 #define REQUEST (1 << 0) 10 #define UINT8 (1 << 1) 11 #define UINT16 (1 << 2) 12 #define SINT16 (1 << 3) 13 #define UINT32 (1 << 4) 14 #define SINT32 (1 << 5) 15 #define IPV4 (1 << 6) 16 #define STRING (1 << 7) 17 #define PAIR (1 << 8) 18 #define ARRAY (1 << 9) 19 #define RFC3361 (1 << 10) 20 #define RFC3397 (1 << 11) 21 #define RFC3442 (1 << 12) 22 23 struct dhcp_opt { 24 uint8_t option; 25 int type; 26 const char *var; 27 }; 28 29 static const struct dhcp_opt const dhcp_opts[] = { 30 { 1, IPV4 | REQUEST, "subnet_mask" }, 31 { 2, UINT32, "time_offset" }, 32 { 3, IPV4 | ARRAY | REQUEST, "routers" }, 33 { 4, IPV4 | ARRAY, "time_servers" }, 34 { 5, IPV4 | ARRAY, "ien116_name_servers" }, 35 { 6, IPV4 | ARRAY, "domain_name_servers" }, 36 { 7, IPV4 | ARRAY, "log_servers" }, 37 { 8, IPV4 | ARRAY, "cookie_servers" }, 38 { 9, IPV4 | ARRAY, "lpr_servers" }, 39 { 10, IPV4 | ARRAY, "impress_servers" }, 40 { 11, IPV4 | ARRAY, "resource_location_servers" }, 41 { 12, STRING, "host_name" }, 42 { 13, UINT16, "boot_size" }, 43 { 14, STRING, "merit_dump" }, 44 { 15, STRING, "domain_name" }, 45 { 16, IPV4, "swap_server" }, 46 { 17, STRING, "root_path" }, 47 { 18, STRING, "extensions_path" }, 48 { 19, UINT8, "ip_forwarding" }, 49 { 20, UINT8, "non_local_source_routing" }, 50 { 21, IPV4 | ARRAY, "policy_filter" }, 51 { 22, SINT16, "max_dgram_reassembly" }, 52 { 23, UINT16, "default_ip_ttl" }, 53 { 24, UINT32, "path_mtu_aging_timeout" }, 54 { 25, UINT16 | ARRAY, "path_mtu_plateau_table" }, 55 { 26, UINT16, "interface_mtu" }, 56 { 27, UINT8, "all_subnets_local" }, 57 { 28, IPV4 | REQUEST, "broadcast_address" }, 58 { 29, UINT8, "perform_mask_discovery" }, 59 { 30, UINT8, "mask_supplier" }, 60 { 31, UINT8, "router_discovery" }, 61 { 32, IPV4, "router_solicitation_address" }, 62 { 33, IPV4 | ARRAY | REQUEST, "static_routes" }, 63 { 34, UINT8, "trailer_encapsulation" }, 64 { 35, UINT32, "arp_cache_timeout" }, 65 { 36, UINT16, "ieee802_3_encapsulation" }, 66 { 37, UINT8, "default_tcp_ttl" }, 67 { 38, UINT32, "tcp_keepalive_interval" }, 68 { 39, UINT8, "tcp_keepalive_garbage" }, 69 { 40, STRING, "nis_domain" }, 70 { 41, IPV4 | ARRAY, "nis_servers" }, 71 { 42, IPV4 | ARRAY, "ntp_servers" }, 72 { 43, STRING, "vendor_encapsulated_options" }, 73 { 44, IPV4 | ARRAY, "netbios_name_servers" }, 74 { 45, IPV4, "netbios_dd_server" }, 75 { 46, UINT8, "netbios_node_type" }, 76 { 47, STRING, "netbios_scope" }, 77 { 48, IPV4 | ARRAY, "font_servers" }, 78 { 49, IPV4 | ARRAY, "x_display_manager" }, 79 { 50, IPV4, "dhcp_requested_address" }, 80 { 51, UINT32 | REQUEST, "dhcp_lease_time" }, 81 { 52, UINT8, "dhcp_option_overload" }, 82 { 53, UINT8, "dhcp_message_type" }, 83 { 54, IPV4, "dhcp_server_identifier" }, 84 { 55, UINT8 | ARRAY, "dhcp_parameter_request_list" }, 85 { 56, STRING, "dhcp_message" }, 86 { 57, UINT16, "dhcp_max_message_size" }, 87 { 58, UINT32 | REQUEST, "dhcp_renewal_time" }, 88 { 59, UINT32 | REQUEST, "dhcp_rebinding_time" }, 89 { 64, STRING, "nisplus_domain" }, 90 { 65, IPV4 | ARRAY, "nisplus_servers" }, 91 { 66, STRING, "tftp_server_name" }, 92 { 67, STRING, "bootfile_name" }, 93 { 68, IPV4 | ARRAY, "mobile_ip_home_agent" }, 94 { 69, IPV4 | ARRAY, "smtp_server" }, 95 { 70, IPV4 | ARRAY, "pop_server" }, 96 { 71, IPV4 | ARRAY, "nntp_server" }, 97 { 72, IPV4 | ARRAY, "www_server" }, 98 { 73, IPV4 | ARRAY, "finger_server" }, 99 { 74, IPV4 | ARRAY, "irc_server" }, 100 { 75, IPV4 | ARRAY, "streettalk_server" }, 101 { 76, IPV4 | ARRAY, "streettalk_directory_assistance_server" }, 102 { 77, STRING, "user_class" }, 103 { 85, IPV4 | ARRAY, "nds_servers" }, 104 { 86, STRING, "nds_tree_name" }, 105 { 87, STRING, "nds_context" }, 106 { 88, STRING | RFC3397, "bcms_controller_names" }, 107 { 89, IPV4 | ARRAY, "bcms_controller_address" }, 108 { 91, UINT32, "client_last_transaction_time" }, 109 { 92, IPV4 | ARRAY, "associated_ip" }, 110 { 98, STRING, "uap_servers" }, 111 { 112, IPV4 | ARRAY, "netinfo_server_address" }, 112 { 113, STRING, "netinfo_server_tag" }, 113 { 114, STRING, "default_url" }, 114 { 118, IPV4, "subnet_selection" }, 115 { 119, STRING | RFC3397, "domain_search" }, 116 { 121, RFC3442 | REQUEST, "classless_static_routes" }, 117 { 249, RFC3442, "ms-classless_static_routes" }, 118 { 0, 0, NULL } 119 }; 120 121 struct dhcp_message * 122 get_lease(const char *leasefile) 123 { 124 int fd; 125 struct dhcp_message *dhcp; 126 ssize_t bytes; 127 128 fd = open(leasefile, O_RDONLY); 129 if (fd == -1) 130 return NULL; 131 dhcp = malloc(sizeof(*dhcp)); 132 memset(dhcp, 0, sizeof(*dhcp)); 133 bytes = read(fd, dhcp, sizeof(*dhcp)); 134 close(fd); 135 if (bytes < 0) { 136 free(dhcp); 137 dhcp = NULL; 138 } 139 return dhcp; 140 } 141 142 static uint8_t *dhcp_opt_buffer = NULL; 143 144 static int 145 valid_length(uint8_t option, int dl, int *type) 146 { 147 const struct dhcp_opt *opt; 148 ssize_t sz; 149 150 if (dl == 0) 151 return -1; 152 153 for (opt = dhcp_opts; opt->option; opt++) { 154 if (opt->option != option) 155 continue; 156 157 if (type) 158 *type = opt->type; 159 160 if (opt->type == 0 || opt->type & STRING || opt->type & RFC3442) 161 return 0; 162 163 sz = 0; 164 if (opt->type & UINT32 || opt->type & IPV4) 165 sz = sizeof(uint32_t); 166 if (opt->type & UINT16) 167 sz = sizeof(uint16_t); 168 if (opt->type & UINT8) 169 sz = sizeof(uint8_t); 170 if (opt->type & IPV4 || opt->type & ARRAY) 171 return dl % sz; 172 return (dl == sz ? 0 : -1); 173 } 174 175 /* unknown option, so let it pass */ 176 return 0; 177 } 178 179 static void 180 free_option_buffer(void) 181 { 182 free(dhcp_opt_buffer); 183 } 184 185 186 #define get_option_raw(dhcp, opt) get_option(dhcp, opt, NULL, NULL) 187 static const uint8_t * 188 get_option(const struct dhcp_message *dhcp, uint8_t opt, int *len, int *type) 189 { 190 const uint8_t *p = dhcp->options; 191 const uint8_t *e = p + sizeof(dhcp->options); 192 uint8_t l, ol = 0; 193 uint8_t o = 0; 194 uint8_t overl = 0; 195 uint8_t *bp = NULL; 196 const uint8_t *op = NULL; 197 int bl = 0; 198 199 while (p < e) { 200 o = *p++; 201 if (o == opt) { 202 if (op) { 203 if (!dhcp_opt_buffer) { 204 dhcp_opt_buffer = malloc(sizeof(struct dhcp_message)); 205 atexit(free_option_buffer); 206 } 207 if (!bp) 208 bp = dhcp_opt_buffer; 209 memcpy(bp, op, ol); 210 bp += ol; 211 } 212 ol = *p; 213 op = p + 1; 214 bl += ol; 215 } 216 switch (o) { 217 case DHO_PAD: 218 continue; 219 case DHO_END: 220 if (overl & 1) { 221 /* bit 1 set means parse boot file */ 222 overl &= ~1; 223 p = dhcp->bootfile; 224 e = p + sizeof(dhcp->bootfile); 225 } else if (overl & 2) { 226 /* bit 2 set means parse server name */ 227 overl &= ~2; 228 p = dhcp->servername; 229 e = p + sizeof(dhcp->servername); 230 } else 231 goto exit; 232 break; 233 case DHO_OPTIONSOVERLOADED: 234 /* Ensure we only get this option once */ 235 if (!overl) 236 overl = p[1]; 237 break; 238 } 239 l = *p++; 240 p += l; 241 } 242 243 exit: 244 if (valid_length(o, bl, type) == -1) { 245 errno = EINVAL; 246 return NULL; 247 } 248 if (len) 249 *len = bl; 250 if (bp) { 251 memcpy(bp, op, ol); 252 return (const uint8_t *)&dhcp_opt_buffer; 253 } 254 if (op) 255 return op; 256 errno = ENOENT; 257 return NULL; 258 } 259 260 int 261 get_option_addr32(uint32_t *a, const struct dhcp_message *dhcp, uint8_t option) 262 { 263 const uint8_t *p = get_option_raw(dhcp, option); 264 265 if (!p) 266 return -1; 267 memcpy(a, p, sizeof(*a)); 268 return 0; 269 } 270 271 int 272 get_option_uint32(uint32_t *i, const struct dhcp_message *dhcp, uint8_t option) 273 { 274 uint32_t a; 275 276 if (get_option_addr32(&a, dhcp, option) == -1) 277 return -1; 278 279 *i = ntohl(a); 280 return 0; 281 } 282 283 uint32_t 284 get_netmask(uint32_t addr) 285 { 286 uint32_t dst; 287 288 if (addr == 0) 289 return 0; 290 291 dst = htonl(addr); 292 if (IN_CLASSA(dst)) 293 return ntohl(IN_CLASSA_NET); 294 if (IN_CLASSB (dst)) 295 return ntohl(IN_CLASSB_NET); 296 if (IN_CLASSC (dst)) 297 return ntohl(IN_CLASSC_NET); 298 299 return 0; 300 } 301 302 void showlease(struct dhcp_lease *lease) 303 { 304 printf("addr: %s\n", inet_ntoa(lease->addr)); 305 printf("net: %s\n", inet_ntoa(lease->net)); 306 printf("leasetime: %d\n", lease->leasetime); 307 printf("renew: %d\n", lease->renewaltime); 308 printf("rebind: %d\n", lease->rebindtime); 309 printf("server: %s\n", inet_ntoa(lease->server)); 310 } 311 #define MAX_LEASETIME 2147460 312 313 int 314 main(int argc, char *argv[]) 315 { 316 struct dhcp_message *dhcp; 317 struct dhcp_lease *lease; 318 char leasefile[PATH_MAX]; 319 320 if (argc < 2) { 321 fprintf(stderr, "Usage: %s <interface>\n", argv[0]); 322 exit(1); 323 } 324 snprintf(leasefile, PATH_MAX, LEASEFILE, argv[1]); 325 if ((dhcp = get_lease(leasefile)) == NULL) { 326 fprintf(stderr, "Couldn't read lease file: %s\n", strerror(errno)); 327 exit(1); 328 } 329 lease = malloc(sizeof(*lease)); 330 lease->frominfo = 0; 331 lease->addr.s_addr = dhcp->yiaddr; 332 333 if (get_option_addr32(&lease->net.s_addr, dhcp, DHO_SUBNETMASK) == -1) 334 lease->net.s_addr = get_netmask(dhcp->yiaddr); 335 if (get_option_uint32(&lease->leasetime, dhcp, DHO_LEASETIME) != 0) 336 lease->leasetime = DEFAULT_LEASETIME; 337 get_option_addr32(&lease->server.s_addr, dhcp, DHO_SERVERID); 338 /* Dm: limit lease time value to avoid negative numbers when 339 converting to milliseconds */ 340 if ((lease->leasetime != ~0U) && (lease->leasetime > MAX_LEASETIME)) 341 lease->leasetime = MAX_LEASETIME; 342 if (get_option_uint32(&lease->renewaltime, dhcp, DHO_RENEWALTIME) != 0) 343 lease->renewaltime = 0; 344 if (get_option_uint32(&lease->rebindtime, dhcp, DHO_REBINDTIME) != 0) 345 lease->rebindtime = 0; 346 showlease(lease); 347 free(lease); 348 return 0; 349 } 350
