hush/networking/udhcp/common.h
Denys Vlasenko c7dc79e71d udhcpd: untangle incredibly messy handling of DHCPREQUEST
Also fixes attacks possible via DHCPDECLINE / DHCPRELEASE

function                                             old     new   delta
udhcpd_main                                         1846    1949    +103
send_renew                                           105     142     +37
send_NAK                                              61       -     -61
send_ACK                                             180       -    -180
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 2/0 up/down: 140/-241)         Total: -101 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2010-03-21 06:15:28 +01:00

202 lines
8.2 KiB
C

/* vi: set sw=4 ts=4: */
/* common.h
*
* 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 tarball for details.
*/
#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
#define DEFAULT_SCRIPT CONFIG_UDHCPC_DEFAULT_SCRIPT
extern const uint8_t MAC_BCAST_ADDR[6]; /* six all-ones */
/*** packet.h ***/
/* 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;
/* Let's see whether compiler understood us right */
struct BUG_bad_sizeof_struct_ip_udp_dhcp_packet {
char BUG_bad_sizeof_struct_ip_udp_dhcp_packet
[(sizeof(struct ip_udp_dhcp_packet) != 576 + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS) ? -1 : 1];
};
// RFC 2131 Table 5: Fields and options used by DHCP clients
//
// Field DHCPDISCOVER DHCPREQUEST DHCPDECLINE,
// DHCPINFORM DHCPRELEASE
// ----- ------------ ----------- -----------
// 'op' BOOTREQUEST BOOTREQUEST BOOTREQUEST
// 'hops' 0 0 0
// 'xid' selected by client 'xid' from server selected by
// DHCPOFFER message client
// 'secs' 0 or seconds since 0 or seconds since 0
// DHCP process started DHCP process started
// 'flags' Set 'BROADCAST' Set 'BROADCAST' 0
// flag if client flag if client
// requires broadcast requires broadcast
// reply reply
// 'ciaddr' 0 (DHCPDISCOVER) 0 or client's 0 (DHCPDECLINE)
// client's network address client's network
// network address (BOUND/RENEW/REBIND) address
// (DHCPINFORM) (DHCPRELEASE)
// 'yiaddr' 0 0 0
// 'siaddr' 0 0 0
// 'giaddr' 0 0 0
// 'chaddr' client's hardware client's hardware client's hardware
// address address address
// 'sname' options, if options, if (unused)
// indicated in indicated in
// 'sname/file' 'sname/file'
// option; otherwise option; otherwise
// unused unused
// 'file' options, if options, if (unused)
// indicated in indicated in
// 'sname/file' 'sname/file'
// option; otherwise option; otherwise
// unused unused
// 'options' options options (unused)
//
// Option DHCPDISCOVER DHCPREQUEST DHCPDECLINE,
// DHCPINFORM DHCPRELEASE
// ------ ------------ ----------- -----------
// Requested IP address MAY MUST (in MUST
// (DISCOVER) SELECTING or (DHCPDECLINE),
// MUST NOT INIT-REBOOT) MUST NOT
// (INFORM) MUST NOT (in (DHCPRELEASE)
// BOUND or
// RENEWING)
// IP address lease time MAY MAY MUST NOT
// (DISCOVER)
// MUST NOT
// (INFORM)
// Use 'file'/'sname' fields MAY MAY MAY
// Client identifier MAY MAY MAY
// Vendor class identifier MAY MAY MUST NOT
// Server identifier MUST NOT MUST (after MUST
// SELECTING)
// MUST NOT (after
// INIT-REBOOT,
// BOUND, RENEWING
// or REBINDING)
// Parameter request list MAY MAY MUST NOT
// Maximum message size MAY MAY MUST NOT
// Message SHOULD NOT SHOULD NOT SHOULD
// Site-specific MAY MAY MUST NOT
// All others MAY MAY MUST NOT
uint16_t udhcp_checksum(void *addr, int count) FAST_FUNC;
void udhcp_init_header(struct dhcp_packet *packet, char type) FAST_FUNC;
/*int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd); - in dhcpc.h */
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_ip, int source_port,
uint32_t dest_ip, 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_ip, int source_port,
uint32_t dest_ip, int dest_port) FAST_FUNC;
/**/
void udhcp_run_script(struct dhcp_packet *packet, const char *name) FAST_FUNC;
// Still need to clean these up...
/* from options.h */
#define get_option udhcp_get_option
#define end_option udhcp_end_option
#define add_option_string udhcp_add_option_string
#define add_simple_option udhcp_add_simple_option
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_raw_socket(int ifindex) 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) FAST_FUNC;
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
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 udhcp_dump_packet(...) ((void)0)
# define log1(...) ((void)0)
# define log2(...) ((void)0)
# define log3(...) ((void)0)
#endif
POP_SAVED_FUNCTION_VISIBILITY
#endif