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      1 /*
      2  * dhcpcd - DHCP client daemon
      3  * Copyright (c) 2006-2008 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 <stdint.h>
     35 
     36 #include "common.h"
     37 
     38 /* Max MTU - defines dhcp option length */
     39 #define MTU_MAX             1500
     40 #define MTU_MIN             576
     41 
     42 /* UDP port numbers for DHCP */
     43 #define DHCP_SERVER_PORT    67
     44 #define DHCP_CLIENT_PORT    68
     45 
     46 #define MAGIC_COOKIE        0x63825363
     47 #define BROADCAST_FLAG      0x8000
     48 
     49 /* DHCP message OP code */
     50 #define DHCP_BOOTREQUEST    1
     51 #define DHCP_BOOTREPLY      2
     52 
     53 /* DHCP message type */
     54 #define DHCP_DISCOVER       1
     55 #define DHCP_OFFER          2
     56 #define DHCP_REQUEST        3
     57 #define DHCP_DECLINE        4
     58 #define DHCP_ACK            5
     59 #define DHCP_NAK            6
     60 #define DHCP_RELEASE        7
     61 #define DHCP_INFORM         8
     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 #define DHCP_ARP_FAIL		10
     71 
     72 /* number of usecs in a second. */
     73 #define USECS_SECOND		1000000
     74 /* As we use timevals, we should use the usec part for
     75  * greater randomisation. */
     76 #define DHCP_RAND_MIN_U		DHCP_RAND_MIN * USECS_SECOND
     77 #define DHCP_RAND_MAX_U		DHCP_RAND_MAX * USECS_SECOND
     78 #define PROBE_MIN_U		PROBE_MIN * USECS_SECOND
     79 #define PROBE_MAX_U		PROBE_MAX * USECS_SECOND
     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_FQDN                   = 81,
    110 	DHO_DNSSEARCH              = 119, /* RFC 3397 */
    111 	DHO_CSR                    = 121, /* RFC 3442 */
    112 	DHO_MSCSR                  = 249, /* MS code for RFC 3442 */
    113 	DHO_END                    = 255
    114 };
    115 
    116 /* FQDN values - lsnybble used in flags
    117  * hsnybble to create order
    118  * and to allow 0x00 to mean disable
    119  */
    120 enum FQDN {
    121 	FQDN_DISABLE    = 0x00,
    122 	FQDN_NONE       = 0x18,
    123 	FQDN_PTR        = 0x20,
    124 	FQDN_BOTH       = 0x31
    125 };
    126 
    127 /* Sizes for DHCP options */
    128 #define DHCP_CHADDR_LEN         16
    129 #define SERVERNAME_LEN          64
    130 #define BOOTFILE_LEN            128
    131 #define DHCP_UDP_LEN            (14 + 20 + 8)
    132 #define DHCP_FIXED_LEN          (DHCP_UDP_LEN + 226)
    133 #define DHCP_OPTION_LEN         (MTU_MAX - DHCP_FIXED_LEN)
    134 
    135 /* Some crappy DHCP servers require the BOOTP minimum length */
    136 #define BOOTP_MESSAGE_LENTH_MIN 300
    137 
    138 struct dhcp_message {
    139 	uint8_t op;           /* message type */
    140 	uint8_t hwtype;       /* hardware address type */
    141 	uint8_t hwlen;        /* hardware address length */
    142 	uint8_t hwopcount;    /* should be zero in client message */
    143 	uint32_t xid;            /* transaction id */
    144 	uint16_t secs;           /* elapsed time in sec. from boot */
    145 	uint16_t flags;
    146 	uint32_t ciaddr;         /* (previously allocated) client IP */
    147 	uint32_t yiaddr;         /* 'your' client IP address */
    148 	uint32_t siaddr;         /* should be zero in client's messages */
    149 	uint32_t giaddr;         /* should be zero in client's messages */
    150 	uint8_t chaddr[DHCP_CHADDR_LEN];  /* client's hardware address */
    151 	uint8_t servername[SERVERNAME_LEN];    /* server host name */
    152 	uint8_t bootfile[BOOTFILE_LEN];    /* boot file name */
    153 	uint32_t cookie;
    154 	uint8_t options[DHCP_OPTION_LEN]; /* message options - cookie */
    155 } _packed;
    156 
    157 struct dhcp_lease {
    158 	struct in_addr addr;
    159 	struct in_addr net;
    160 	struct in_addr brd;
    161 	uint32_t leasetime;
    162 	uint32_t renewaltime;
    163 	uint32_t rebindtime;
    164 	struct in_addr server;
    165 	time_t leasedfrom;
    166 	struct timeval boundtime;
    167 	uint8_t frominfo;
    168 	uint32_t cookie;
    169 };
    170 
    171 #include "dhcpcd.h"
    172 #include "if-options.h"
    173 #include "net.h"
    174 
    175 #define add_option_mask(var, val) (var[val >> 3] |= 1 << (val & 7))
    176 #define del_option_mask(var, val) (var[val >> 3] &= ~(1 << (val & 7)))
    177 #define has_option_mask(var, val) (var[val >> 3] & (1 << (val & 7)))
    178 int make_option_mask(uint8_t *, const char *, int);
    179 void print_options(void);
    180 char *get_option_string(const struct dhcp_message *, uint8_t);
    181 int get_option_addr(struct in_addr *, const struct dhcp_message *, uint8_t);
    182 int get_option_uint32(uint32_t *, const struct dhcp_message *, uint8_t);
    183 int get_option_uint16(uint16_t *, const struct dhcp_message *, uint8_t);
    184 int get_option_uint8(uint8_t *, const struct dhcp_message *, uint8_t);
    185 #define is_bootp(m) (m &&						\
    186 	    !IN_LINKLOCAL(htonl((m)->yiaddr)) &&			\
    187 	    get_option_uint8(NULL, m, DHO_MESSAGETYPE) == -1)
    188 struct rt *get_option_routes(const struct dhcp_message *, const char *, int *);
    189 ssize_t configure_env(char **, const char *, const struct dhcp_message *,
    190     const struct if_options *);
    191 
    192 int dhcp_message_add_addr(struct dhcp_message *, uint8_t, struct in_addr);
    193 ssize_t make_message(struct dhcp_message **, const struct interface *,
    194     uint8_t);
    195 int valid_dhcp_packet(unsigned char *);
    196 
    197 ssize_t write_lease(const struct interface *, const struct dhcp_message *);
    198 struct dhcp_message *read_lease(const struct interface *);
    199 void get_lease(struct dhcp_lease *, const struct dhcp_message *);
    200 
    201 #endif
    202