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      1 /*
      2  * dhcpcd - DHCP client daemon
      3  * Copyright (c) 2006-2015 Roy Marples <roy (at) marples.name>
      4  * All rights reserved
      5 
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #ifndef DHCP_H
     29 #define DHCP_H
     30 
     31 #include <arpa/inet.h>
     32 #include <netinet/in.h>
     33 
     34 #include <limits.h>
     35 #include <stdint.h>
     36 
     37 #include "arp.h"
     38 #include "auth.h"
     39 #include "dhcp-common.h"
     40 
     41 /* UDP port numbers for DHCP */
     42 #define DHCP_SERVER_PORT    67
     43 #define DHCP_CLIENT_PORT    68
     44 
     45 #define MAGIC_COOKIE        0x63825363
     46 #define BROADCAST_FLAG      0x8000
     47 
     48 /* DHCP message OP code */
     49 #define DHCP_BOOTREQUEST    1
     50 #define DHCP_BOOTREPLY      2
     51 
     52 /* DHCP message type */
     53 #define DHCP_DISCOVER       1
     54 #define DHCP_OFFER          2
     55 #define DHCP_REQUEST        3
     56 #define DHCP_DECLINE        4
     57 #define DHCP_ACK            5
     58 #define DHCP_NAK            6
     59 #define DHCP_RELEASE        7
     60 #define DHCP_INFORM         8
     61 #define DHCP_FORCERENEW     9
     62 
     63 /* Constants taken from RFC 2131. */
     64 #define T1			0.5
     65 #define T2			0.875
     66 #define DHCP_BASE		4
     67 #define DHCP_MAX		64
     68 #define DHCP_RAND_MIN		-1
     69 #define DHCP_RAND_MAX		1
     70 
     71 #ifdef RFC2131_STRICT
     72 /* Be strictly conformant for section 4.1.1 */
     73 #  define DHCP_MIN_DELAY	1
     74 #  define DHCP_MAX_DELAY	10
     75 #else
     76 /* or mirror the more modern IPv6RS and DHCPv6 delays */
     77 #  define DHCP_MIN_DELAY	0
     78 #  define DHCP_MAX_DELAY	1
     79 #endif
     80 
     81 /* DHCP options */
     82 enum DHO {
     83 	DHO_PAD                    = 0,
     84 	DHO_SUBNETMASK             = 1,
     85 	DHO_ROUTER                 = 3,
     86 	DHO_DNSSERVER              = 6,
     87 	DHO_HOSTNAME               = 12,
     88 	DHO_DNSDOMAIN              = 15,
     89 	DHO_MTU                    = 26,
     90 	DHO_BROADCAST              = 28,
     91 	DHO_STATICROUTE            = 33,
     92 	DHO_NISDOMAIN              = 40,
     93 	DHO_NISSERVER              = 41,
     94 	DHO_NTPSERVER              = 42,
     95 	DHO_VENDOR                 = 43,
     96 	DHO_IPADDRESS              = 50,
     97 	DHO_LEASETIME              = 51,
     98 	DHO_OPTIONSOVERLOADED      = 52,
     99 	DHO_MESSAGETYPE            = 53,
    100 	DHO_SERVERID               = 54,
    101 	DHO_PARAMETERREQUESTLIST   = 55,
    102 	DHO_MESSAGE                = 56,
    103 	DHO_MAXMESSAGESIZE         = 57,
    104 	DHO_RENEWALTIME            = 58,
    105 	DHO_REBINDTIME             = 59,
    106 	DHO_VENDORCLASSID          = 60,
    107 	DHO_CLIENTID               = 61,
    108 	DHO_USERCLASS              = 77,  /* RFC 3004 */
    109 	DHO_RAPIDCOMMIT            = 80,  /* RFC 4039 */
    110 	DHO_FQDN                   = 81,
    111 	DHO_AUTHENTICATION         = 90,  /* RFC 3118 */
    112 	DHO_AUTOCONFIGURE          = 116, /* RFC 2563 */
    113 	DHO_DNSSEARCH              = 119, /* RFC 3397 */
    114 	DHO_CSR                    = 121, /* RFC 3442 */
    115 	DHO_VIVCO                  = 124, /* RFC 3925 */
    116 	DHO_VIVSO                  = 125, /* RFC 3925 */
    117 	DHO_FORCERENEW_NONCE       = 145, /* RFC 6704 */
    118 	DHO_SIXRD                  = 212, /* RFC 5969 */
    119 	DHO_MSCSR                  = 249, /* MS code for RFC 3442 */
    120 	DHO_END                    = 255
    121 };
    122 
    123 /* FQDN values - lsnybble used in flags
    124  * hsnybble to create order
    125  * and to allow 0x00 to mean disable
    126  */
    127 enum FQDN {
    128 	FQDN_DISABLE    = 0x00,
    129 	FQDN_NONE       = 0x18,
    130 	FQDN_PTR        = 0x20,
    131 	FQDN_BOTH       = 0x31
    132 };
    133 
    134 /* Sizes for DHCP options */
    135 #define DHCP_CHADDR_LEN         16
    136 #define SERVERNAME_LEN          64
    137 #define BOOTFILE_LEN            128
    138 #define DHCP_UDP_LEN            (14 + 20 + 8)
    139 #define DHCP_FIXED_LEN          (DHCP_UDP_LEN + 226)
    140 #define DHCP_OPTION_LEN         (MTU_MAX - DHCP_FIXED_LEN)
    141 
    142 /* Some crappy DHCP servers require the BOOTP minimum length */
    143 #define BOOTP_MESSAGE_LENTH_MIN 300
    144 
    145 /* Flags for the OPTIONSOVERLOADED field. */
    146 #define OPTION_OVERLOADED_BOOT_FILE 1
    147 #define OPTION_OVERLOADED_SERVER_NAME 2
    148 
    149 /* Don't import common.h as that defines __unused which causes problems
    150  * on some Linux systems which define it as part of a structure */
    151 #if __GNUC__ > 2 || defined(__INTEL_COMPILER)
    152 # ifndef __packed
    153 #  define __packed   __attribute__((__packed__))
    154 # endif
    155 #else
    156 # ifndef __packed
    157 #  define __packed
    158 # endif
    159 #endif
    160 
    161 struct dhcp_message {
    162 	uint8_t op;           /* message type */
    163 	uint8_t hwtype;       /* hardware address type */
    164 	uint8_t hwlen;        /* hardware address length */
    165 	uint8_t hwopcount;    /* should be zero in client message */
    166 	uint32_t xid;            /* transaction id */
    167 	uint16_t secs;           /* elapsed time in sec. from boot */
    168 	uint16_t flags;
    169 	uint32_t ciaddr;         /* (previously allocated) client IP */
    170 	uint32_t yiaddr;         /* 'your' client IP address */
    171 	uint32_t siaddr;         /* should be zero in client's messages */
    172 	uint32_t giaddr;         /* should be zero in client's messages */
    173 	uint8_t chaddr[DHCP_CHADDR_LEN];  /* client's hardware address */
    174 	uint8_t servername[SERVERNAME_LEN];    /* server host name */
    175 	uint8_t bootfile[BOOTFILE_LEN];    /* boot file name */
    176 	uint32_t cookie;
    177 	uint8_t options[DHCP_OPTION_LEN]; /* message options - cookie */
    178 } __packed;
    179 
    180 struct dhcp_option_iterator {
    181 	const struct dhcp_message *message;
    182 	const uint8_t *ptr;
    183 	const uint8_t *end;
    184 	uint8_t extra_option_locations;
    185 	uint8_t extra_option_locations_set;
    186 };
    187 
    188 struct dhcp_lease {
    189 	struct in_addr addr;
    190 	struct in_addr net;
    191 	struct in_addr brd;
    192 	uint32_t leasetime;
    193 	uint32_t renewaltime;
    194 	uint32_t rebindtime;
    195 	struct in_addr server;
    196 	uint8_t frominfo;
    197 	uint32_t cookie;
    198 };
    199 
    200 /* Extra data about servers stored in the lease file after the dhcp_message */
    201 struct dhcp_server_info {
    202 	uint8_t gw_hwlen;
    203 	unsigned char gw_hwaddr[HWADDR_LEN];
    204 };
    205 
    206 enum DHS {
    207 	DHS_INIT,
    208 	DHS_DISCOVER,
    209 	DHS_REQUEST,
    210 	DHS_BOUND,
    211 	DHS_RENEW,
    212 	DHS_REBIND,
    213 	DHS_REBOOT,
    214 	DHS_INFORM,
    215 	DHS_RENEW_REQUESTED,
    216 	DHS_IPV4LL_BOUND,
    217 	DHS_PROBE
    218 };
    219 
    220 struct dhcp_state {
    221 	enum DHS state;
    222 	struct dhcp_message *sent;
    223 	struct dhcp_message *offer;
    224 	struct dhcp_message *new;
    225 	struct dhcp_message *old;
    226 	struct dhcp_lease lease;
    227 	const char *reason;
    228 	time_t interval;
    229 	time_t nakoff;
    230 	uint32_t xid;
    231 	int socket;
    232 
    233 	int raw_fd;
    234 	int arp_fd;
    235 	size_t buffer_size, buffer_len, buffer_pos;
    236 	unsigned char *buffer;
    237 
    238 	struct in_addr addr;
    239 	struct in_addr net;
    240 	struct in_addr dst;
    241 	uint8_t added;
    242 
    243 	char leasefile[PATH_MAX];
    244 	time_t start_uptime;
    245 
    246 	unsigned char *clientid;
    247 
    248 	struct authstate auth;
    249 	struct arp_statehead arp_states;
    250 
    251 	size_t arping_index;
    252 
    253 	struct arp_state *arp_ipv4ll;
    254 	unsigned int conflicts;
    255 	int nak_receive_count;
    256 	int failed_address_offer_count;
    257 	struct in_addr failed;
    258 	time_t defend;
    259 	char randomstate[128];
    260 	struct dhcp_server_info server_info;
    261 };
    262 
    263 #define D_STATE(ifp)							       \
    264 	((struct dhcp_state *)(ifp)->if_data[IF_DATA_DHCP])
    265 #define D_CSTATE(ifp)							       \
    266 	((const struct dhcp_state *)(ifp)->if_data[IF_DATA_DHCP])
    267 #define D_STATE_RUNNING(ifp)						       \
    268 	(D_CSTATE((ifp)) && D_CSTATE((ifp))->new && D_CSTATE((ifp))->reason)
    269 
    270 #include "dhcpcd.h"
    271 #include "if-options.h"
    272 
    273 #ifdef INET
    274 char *decode_rfc3361(const uint8_t *, size_t);
    275 ssize_t decode_rfc3442(char *, size_t, const uint8_t *p, size_t);
    276 ssize_t decode_rfc5969(char *, size_t, const uint8_t *p, size_t);
    277 
    278 void dhcp_printoptions(const struct dhcpcd_ctx *,
    279     const struct dhcp_opt *, size_t);
    280 int get_option_addr(struct dhcpcd_ctx *,struct in_addr *,
    281     const struct dhcp_message *, uint8_t);
    282 #define IS_BOOTP(i, m) ((m) &&						    \
    283 	    !IN_LINKLOCAL(htonl((m)->yiaddr)) &&			    \
    284 	    get_option_uint8((i)->ctx, NULL, (m), DHO_MESSAGETYPE) == -1)
    285 struct rt_head *get_option_routes(struct interface *,
    286     const struct dhcp_message *);
    287 ssize_t dhcp_env(char **, const char *, const struct dhcp_message *,
    288     const struct interface *);
    289 
    290 uint32_t dhcp_xid(const struct interface *);
    291 struct dhcp_message *dhcp_message_new(const struct in_addr *addr,
    292     const struct in_addr *mask);
    293 int dhcp_message_add_addr(struct dhcp_message *, uint8_t, struct in_addr);
    294 ssize_t make_message(struct dhcp_message **, const struct interface *,
    295     uint8_t);
    296 int valid_dhcp_packet(unsigned char *);
    297 
    298 void dhcp_handleifa(int, struct interface *,
    299     const struct in_addr *, const struct in_addr *, const struct in_addr *,
    300     int);
    301 
    302 void dhcp_drop(struct interface *, const char *);
    303 void dhcp_start(struct interface *);
    304 void dhcp_stop(struct interface *);
    305 void dhcp_discover(void *);
    306 void dhcp_inform(struct interface *);
    307 void dhcp_bind(struct interface *, struct arp_state *);
    308 void dhcp_reboot_newopts(struct interface *, unsigned long long);
    309 void dhcp_close(struct interface *);
    310 void dhcp_free(struct interface *);
    311 int dhcp_dump(struct interface *);
    312 #else
    313 #define dhcp_drop(a, b) {}
    314 #define dhcp_start(a) {}
    315 #define dhcp_reboot(a, b) (b = b)
    316 #define dhcp_reboot_newopts(a, b) (b = b)
    317 #define dhcp_close(a) {}
    318 #define dhcp_free(a) {}
    319 #define dhcp_dump(a) (-1)
    320 #endif
    321 
    322 #endif
    323