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busybox/networking/udhcp/common.h
Michel Stam 9f41271f3c udhcpd: add option for tweaking arpping 
Some clients have a very short timeout for sending the DHCP
DISCOVER, shorter than the arpping timeout of 2000 milliseconds
that udhcpd uses by default.

This patch allows tweaking the timeout, or disabling of arpping
altogether, at the risk of handing out addresses which are
already in use.

function                                             old     new   delta
udhcpd_main                                         1460    1501     +41
udhcpc_main                                         2814    2851     +37
packed_usage                                       29957   29974     +17
arpping                                              477     493     +16
find_free_or_expired_nip                             161     174     +13
send_offer                                           285     292      +7
nobody_responds_to_arp                                85      89      +4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 7/0 up/down: 135/0)             Total: 135 bytes

Signed-off-by: Michel Stam <m.stam@fugro.nl>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2014-10-30 11:59:04 +01:00

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/* vi: set sw=4 ts=4: */
/*
* Russ Dill <Russ.Dill@asu.edu> September 2001
* Rewritten by Vladimir Oleynik <dzo@simtreas.ru> (C) 2003
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#ifndef UDHCP_COMMON_H
#define UDHCP_COMMON_H 1
#include "libbb.h"
#include <netinet/udp.h>
#include <netinet/ip.h>
PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
extern const uint8_t MAC_BCAST_ADDR[6] ALIGN2; /* six all-ones */
/*** DHCP packet ***/
/* DHCP protocol. See RFC 2131 */
#define DHCP_MAGIC 0x63825363
#define DHCP_OPTIONS_BUFSIZE 308
#define BOOTREQUEST 1
#define BOOTREPLY 2
//TODO: rename ciaddr/yiaddr/chaddr
struct dhcp_packet {
uint8_t op; /* BOOTREQUEST or BOOTREPLY */
uint8_t htype; /* hardware address type. 1 = 10mb ethernet */
uint8_t hlen; /* hardware address length */
uint8_t hops; /* used by relay agents only */
uint32_t xid; /* unique id */
uint16_t secs; /* elapsed since client began acquisition/renewal */
uint16_t flags; /* only one flag so far: */
#define BROADCAST_FLAG 0x8000 /* "I need broadcast replies" */
uint32_t ciaddr; /* client IP (if client is in BOUND, RENEW or REBINDING state) */
uint32_t yiaddr; /* 'your' (client) IP address */
/* IP address of next server to use in bootstrap, returned in DHCPOFFER, DHCPACK by server */
uint32_t siaddr_nip;
uint32_t gateway_nip; /* relay agent IP address */
uint8_t chaddr[16]; /* link-layer client hardware address (MAC) */
uint8_t sname[64]; /* server host name (ASCIZ) */
uint8_t file[128]; /* boot file name (ASCIZ) */
uint32_t cookie; /* fixed first four option bytes (99,130,83,99 dec) */
uint8_t options[DHCP_OPTIONS_BUFSIZE + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS];
} PACKED;
#define DHCP_PKT_SNAME_LEN 64
#define DHCP_PKT_FILE_LEN 128
#define DHCP_PKT_SNAME_LEN_STR "64"
#define DHCP_PKT_FILE_LEN_STR "128"
struct ip_udp_dhcp_packet {
struct iphdr ip;
struct udphdr udp;
struct dhcp_packet data;
} PACKED;
struct udp_dhcp_packet {
struct udphdr udp;
struct dhcp_packet data;
} PACKED;
enum {
IP_UDP_DHCP_SIZE = sizeof(struct ip_udp_dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
UDP_DHCP_SIZE = sizeof(struct udp_dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
DHCP_SIZE = sizeof(struct dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
};
/* Let's see whether compiler understood us right */
struct BUG_bad_sizeof_struct_ip_udp_dhcp_packet {
char c[IP_UDP_DHCP_SIZE == 576 ? 1 : -1];
};
/*** Options ***/
enum {
OPTION_IP = 1,
OPTION_IP_PAIR,
OPTION_STRING,
/* Opts of STRING_HOST type will be sanitized before they are passed
* to udhcpc script's environment: */
OPTION_STRING_HOST,
// OPTION_BOOLEAN,
OPTION_U8,
OPTION_U16,
// OPTION_S16,
OPTION_U32,
OPTION_S32,
OPTION_BIN,
OPTION_STATIC_ROUTES,
OPTION_6RD,
#if ENABLE_FEATURE_UDHCP_RFC3397
OPTION_DNS_STRING, /* RFC1035 compressed domain name list */
OPTION_SIP_SERVERS,
#endif
OPTION_TYPE_MASK = 0x0f,
/* Client requests this option by default */
OPTION_REQ = 0x10,
/* There can be a list of 1 or more of these */
OPTION_LIST = 0x20,
};
/* DHCP option codes (partial list). See RFC 2132 and
* http://www.iana.org/assignments/bootp-dhcp-parameters/
* Commented out options are handled by common option machinery,
* uncommented ones have special cases (grep for them to see).
*/
#define DHCP_PADDING 0x00
#define DHCP_SUBNET 0x01
//#define DHCP_TIME_OFFSET 0x02 /* (localtime - UTC_time) in seconds. signed */
//#define DHCP_ROUTER 0x03
//#define DHCP_TIME_SERVER 0x04 /* RFC 868 time server (32-bit, 0 = 1.1.1900) */
//#define DHCP_NAME_SERVER 0x05 /* IEN 116 _really_ ancient kind of NS */
//#define DHCP_DNS_SERVER 0x06
//#define DHCP_LOG_SERVER 0x07 /* port 704 UDP log (not syslog)
//#define DHCP_COOKIE_SERVER 0x08 /* "quote of the day" server */
//#define DHCP_LPR_SERVER 0x09
#define DHCP_HOST_NAME 0x0c /* either client informs server or server gives name to client */
//#define DHCP_BOOT_SIZE 0x0d
//#define DHCP_DOMAIN_NAME 0x0f /* server gives domain suffix */
//#define DHCP_SWAP_SERVER 0x10
//#define DHCP_ROOT_PATH 0x11
//#define DHCP_IP_TTL 0x17
//#define DHCP_MTU 0x1a
//#define DHCP_BROADCAST 0x1c
//#define DHCP_ROUTES 0x21
//#define DHCP_NIS_DOMAIN 0x28
//#define DHCP_NIS_SERVER 0x29
//#define DHCP_NTP_SERVER 0x2a
//#define DHCP_WINS_SERVER 0x2c
#define DHCP_REQUESTED_IP 0x32 /* sent by client if specific IP is wanted */
#define DHCP_LEASE_TIME 0x33
#define DHCP_OPTION_OVERLOAD 0x34
#define DHCP_MESSAGE_TYPE 0x35
#define DHCP_SERVER_ID 0x36 /* by default server's IP */
#define DHCP_PARAM_REQ 0x37 /* list of options client wants */
//#define DHCP_ERR_MESSAGE 0x38 /* error message when sending NAK etc */
#define DHCP_MAX_SIZE 0x39
#define DHCP_VENDOR 0x3c /* client's vendor (a string) */
#define DHCP_CLIENT_ID 0x3d /* by default client's MAC addr, but may be arbitrarily long */
//#define DHCP_TFTP_SERVER_NAME 0x42 /* same as 'sname' field */
//#define DHCP_BOOT_FILE 0x43 /* same as 'file' field */
//#define DHCP_USER_CLASS 0x4d /* RFC 3004. set of LASCII strings. "I am a printer" etc */
#define DHCP_FQDN 0x51 /* client asks to update DNS to map its FQDN to its new IP */
//#define DHCP_DOMAIN_SEARCH 0x77 /* RFC 3397. set of ASCIZ string, DNS-style compressed */
//#define DHCP_SIP_SERVERS 0x78 /* RFC 3361. flag byte, then: 0: domain names, 1: IP addrs */
//#define DHCP_STATIC_ROUTES 0x79 /* RFC 3442. (mask,ip,router) tuples */
//#define DHCP_VLAN_ID 0x84 /* 802.1P VLAN ID */
//#define DHCP_VLAN_PRIORITY 0x85 /* 802.1Q VLAN priority */
//#define DHCP_PXE_CONF_FILE 0xd1 /* RFC 5071 Configuration File */
//#define DHCP_PXE_PATH_PREFIX 0xd2 /* RFC 5071 Configuration File */
//#define DHCP_MS_STATIC_ROUTES 0xf9 /* Microsoft's pre-RFC 3442 code for 0x79? */
//#define DHCP_WPAD 0xfc /* MSIE's Web Proxy Autodiscovery Protocol */
#define DHCP_END 0xff
/* Offsets in option byte sequence */
#define OPT_CODE 0
#define OPT_LEN 1
#define OPT_DATA 2
/* Bits in "overload" option */
#define OPTION_FIELD 0
#define FILE_FIELD 1
#define SNAME_FIELD 2
/* DHCP_MESSAGE_TYPE values */
#define DHCPDISCOVER 1 /* client -> server */
#define DHCPOFFER 2 /* client <- server */
#define DHCPREQUEST 3 /* client -> server */
#define DHCPDECLINE 4 /* client -> server */
#define DHCPACK 5 /* client <- server */
#define DHCPNAK 6 /* client <- server */
#define DHCPRELEASE 7 /* client -> server */
#define DHCPINFORM 8 /* client -> server */
#define DHCP_MINTYPE DHCPDISCOVER
#define DHCP_MAXTYPE DHCPINFORM
struct dhcp_optflag {
uint8_t flags;
uint8_t code;
};
struct option_set {
uint8_t *data;
struct option_set *next;
};
extern const struct dhcp_optflag dhcp_optflags[];
extern const char dhcp_option_strings[] ALIGN1;
extern const uint8_t dhcp_option_lengths[] ALIGN1;
unsigned FAST_FUNC udhcp_option_idx(const char *name);
uint8_t *udhcp_get_option(struct dhcp_packet *packet, int code) FAST_FUNC;
int udhcp_end_option(uint8_t *optionptr) FAST_FUNC;
void udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt) FAST_FUNC;
void udhcp_add_simple_option(struct dhcp_packet *packet, uint8_t code, uint32_t data) FAST_FUNC;
#if ENABLE_FEATURE_UDHCP_RFC3397
char *dname_dec(const uint8_t *cstr, int clen, const char *pre) FAST_FUNC;
uint8_t *dname_enc(const uint8_t *cstr, int clen, const char *src, int *retlen) FAST_FUNC;
#endif
struct option_set *udhcp_find_option(struct option_set *opt_list, uint8_t code) FAST_FUNC;
// RFC 2131 Table 5: Fields and options used by DHCP clients
//
// Fields 'hops', 'yiaddr', 'siaddr', 'giaddr' are always zero
//
// Field DHCPDISCOVER DHCPINFORM DHCPREQUEST DHCPDECLINE DHCPRELEASE
// ----- ------------ ------------ ----------- ----------- -----------
// 'xid' selected by client selected by client 'xid' from server selected by client selected by client
// DHCPOFFER message
// 'secs' 0 or seconds since 0 or seconds since 0 or seconds since 0 0
// DHCP process started DHCP process started DHCP process started
// 'flags' Set 'BROADCAST' Set 'BROADCAST' Set 'BROADCAST' 0 0
// flag if client flag if client flag if client
// requires broadcast requires broadcast requires broadcast
// reply reply reply
// 'ciaddr' 0 client's IP 0 or client's IP 0 client's IP
// (BOUND/RENEW/REBIND)
// 'chaddr' client's MAC client's MAC client's MAC client's MAC client's MAC
// 'sname' options or sname options or sname options or sname (unused) (unused)
// 'file' options or file options or file options or file (unused) (unused)
// 'options' options options options message type opt message type opt
//
// Option DHCPDISCOVER DHCPINFORM DHCPREQUEST DHCPDECLINE DHCPRELEASE
// ------ ------------ ---------- ----------- ----------- -----------
// Requested IP address MAY MUST NOT MUST (in MUST MUST NOT
// SELECTING or
// INIT-REBOOT)
// MUST NOT (in
// BOUND or
// RENEWING)
// IP address lease time MAY MUST NOT MAY MUST NOT MUST NOT
// Use 'file'/'sname' fields MAY MAY MAY MAY MAY
// Client identifier MAY MAY MAY MAY MAY
// Vendor class identifier MAY MAY MAY MUST NOT MUST NOT
// Server identifier MUST NOT MUST NOT MUST (after MUST MUST
// SELECTING)
// MUST NOT (after
// INIT-REBOOT,
// BOUND, RENEWING
// or REBINDING)
// Parameter request list MAY MAY MAY MUST NOT MUST NOT
// Maximum message size MAY MAY MAY MUST NOT MUST NOT
// Message SHOULD NOT SHOULD NOT SHOULD NOT SHOULD SHOULD
// Site-specific MAY MAY MAY MUST NOT MUST NOT
// All others MAY MAY MAY MUST NOT MUST NOT
/*** Logging ***/
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
extern unsigned dhcp_verbose;
# define log1(...) do { if (dhcp_verbose >= 1) bb_info_msg(__VA_ARGS__); } while (0)
# if CONFIG_UDHCP_DEBUG >= 2
void udhcp_dump_packet(struct dhcp_packet *packet) FAST_FUNC;
# define log2(...) do { if (dhcp_verbose >= 2) bb_info_msg(__VA_ARGS__); } while (0)
# else
# define udhcp_dump_packet(...) ((void)0)
# define log2(...) ((void)0)
# endif
# if CONFIG_UDHCP_DEBUG >= 3
# define log3(...) do { if (dhcp_verbose >= 3) bb_info_msg(__VA_ARGS__); } while (0)
# else
# define log3(...) ((void)0)
# endif
#else
# define IF_UDHCP_VERBOSE(...)
# define udhcp_dump_packet(...) ((void)0)
# define log1(...) ((void)0)
# define log2(...) ((void)0)
# define log3(...) ((void)0)
#endif
/*** Other shared functions ***/
/* 2nd param is "uint32_t*" */
int FAST_FUNC udhcp_str2nip(const char *str, void *arg);
/* 2nd param is "struct option_set**" */
int FAST_FUNC udhcp_str2optset(const char *str, void *arg);
void udhcp_init_header(struct dhcp_packet *packet, char type) FAST_FUNC;
int udhcp_recv_kernel_packet(struct dhcp_packet *packet, int fd) FAST_FUNC;
int udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
uint32_t source_nip, int source_port,
uint32_t dest_nip, int dest_port, const uint8_t *dest_arp,
int ifindex) FAST_FUNC;
int udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
uint32_t source_nip, int source_port,
uint32_t dest_nip, int dest_port) FAST_FUNC;
void udhcp_sp_setup(void) FAST_FUNC;
int udhcp_sp_fd_set(fd_set *rfds, int extra_fd) FAST_FUNC;
int udhcp_sp_read(const fd_set *rfds) FAST_FUNC;
int udhcp_read_interface(const char *interface, int *ifindex, uint32_t *nip, uint8_t *mac) FAST_FUNC;
int udhcp_listen_socket(/*uint32_t ip,*/ int port, const char *inf) FAST_FUNC;
/* Returns 1 if no reply received */
int arpping(uint32_t test_nip,
const uint8_t *safe_mac,
uint32_t from_ip,
uint8_t *from_mac,
const char *interface,
unsigned timeo) FAST_FUNC;
/* note: ip is a pointer to an IPv6 in network order, possibly misaliged */
int sprint_nip6(char *dest, /*const char *pre,*/ const uint8_t *ip) FAST_FUNC;
POP_SAVED_FUNCTION_VISIBILITY
#endif
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