/* * pppd.h - PPP daemon global declarations. * * Copyright (c) 1989 Carnegie Mellon University. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that the above copyright notice and this paragraph are * duplicated in all such forms and that any documentation, * advertising materials, and other materials related to such * distribution and use acknowledge that the software was developed * by Carnegie Mellon University. The name of the * University may not be used to endorse or promote products derived * from this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * $Id$ */ #ifndef __PPPD_H__ #define __PPPD_H__ #include /* for FILE */ #include /* for NGROUPS_MAX */ #include /* for MAXPATHLEN and BSD4_4, if defined */ #include /* for u_int32_t, if defined */ #include /* for struct timeval */ #include #include "rtemsdialer.h" #if defined(__STDC__) #include #define __V(x) x #else #include #define __V(x) (va_alist) va_dcl #define const #define volatile #endif #ifdef INET6 #include "eui64.h" #endif /* * Limits. */ #define NUM_PPP 1 /* One PPP interface supported (per process) */ #define MAXWORDLEN 1024 /* max length of word in file (incl null) */ #define MAXARGS 1 /* max # args to a command */ #define MAXNAMELEN 256 /* max length of hostname or name for auth */ #define MAXSECRETLEN 256 /* max length of password or secret */ /* * Option descriptor structure. */ typedef unsigned char bool; enum opt_type { o_special_noarg = 0, o_special = 1, o_bool, o_int, o_uint32, o_string, }; typedef struct { char *name; /* name of the option */ enum opt_type type; void *addr; char *description; int flags; void *addr2; int upper_limit; int lower_limit; } option_t; /* Values for flags */ #define OPT_VALUE 0xff /* mask for presupplied value */ #define OPT_HEX 0x100 /* int option is in hex */ #define OPT_NOARG 0x200 /* option doesn't take argument */ #define OPT_OR 0x400 /* OR in argument to value */ #define OPT_INC 0x800 /* increment value */ #define OPT_PRIV 0x1000 /* privileged option */ #define OPT_STATIC 0x2000 /* string option goes into static array */ #define OPT_LLIMIT 0x4000 /* check value against lower limit */ #define OPT_ULIMIT 0x8000 /* check value against upper limit */ #define OPT_LIMITS (OPT_LLIMIT|OPT_ULIMIT) #define OPT_ZEROOK 0x10000 /* 0 value is OK even if not within limits */ #define OPT_NOINCR 0x20000 /* value mustn't be increased */ #define OPT_ZEROINF 0x40000 /* with OPT_NOINCR, 0 == infinity */ #define OPT_A2INFO 0x100000 /* addr2 -> option_info to update */ #define OPT_A2COPY 0x200000 /* addr2 -> second location to rcv value */ #define OPT_ENABLE 0x400000 /* use *addr2 as enable for option */ #define OPT_PRIVFIX 0x800000 /* can't be overridden if noauth */ #define OPT_PREPASS 0x1000000 /* do this opt in pre-pass to find device */ #define OPT_INITONLY 0x2000000 /* option can only be set in init phase */ #define OPT_DEVEQUIV 0x4000000 /* equiv to device name */ #define OPT_DEVNAM (OPT_PREPASS | OPT_INITONLY | OPT_DEVEQUIV) #define OPT_VAL(x) ((x) & OPT_VALUE) #ifndef GIDSET_TYPE #define GIDSET_TYPE gid_t #endif /* Structure representing a list of permitted IP addresses. */ struct permitted_ip { int permit; /* 1 = permit, 0 = forbid */ u_int32_t base; /* match if (addr & mask) == base */ u_int32_t mask; /* base and mask are in network byte order */ }; /* * Unfortunately, the linux kernel driver uses a different structure * for statistics from the rest of the ports. * This structure serves as a common representation for the bits * pppd needs. */ struct pppd_stats { unsigned int bytes_in; unsigned int bytes_out; }; /* Used for storing a sequence of words. Usually malloced. */ struct wordlist { struct wordlist *next; char *word; }; /* * Global variables. */ extern int pppd_kill_link; /* Signal to terminate processing loop */ extern int hungup; /* Physical layer has disconnected */ extern int pppifunit; /* Interface unit number */ extern char ifname[]; /* Interface name */ extern int pppd_ttyfd; /* Serial device file descriptor */ extern char hostname[]; /* Our hostname */ extern u_char outpacket_buf[]; /* Buffer for outgoing packets */ extern int pppd_phase; /* Current state of link - see values below */ extern int baud_rate; /* Current link speed in bits/sec */ extern int redirect_stderr;/* Connector's stderr should go to file */ extern char peer_authname[];/* Authenticated name of peer */ extern int privileged; /* We were run by real-uid root */ extern int need_holdoff; /* Need holdoff period after link terminates */ extern char **script_env; /* Environment variables for scripts */ extern int detached; /* Have detached from controlling tty */ extern GIDSET_TYPE groups[NGROUPS_MAX]; /* groups the user is in */ extern int ngroups; /* How many groups valid in groups */ extern struct pppd_stats link_stats; /* byte/packet counts etc. for link */ extern int using_pty; /* using pty as device (notty or pty opt.) */ extern int log_to_fd; /* logging to this fd as well as syslog */ extern char *no_ppp_msg; /* message to print if ppp not in kernel */ extern volatile int pppd_status; /* exit status for pppd */ extern int devnam_fixed; /* can no longer change devnam */ extern int unsuccess; /* # unsuccessful connection attempts */ extern int do_callback; /* set if we want to do callback next */ extern int doing_callback; /* set if this is a callback */ extern dialerfp pppd_dialer; /* script dialer function callback */ /* Values for do_callback and doing_callback */ #define CALLBACK_DIALIN 1 /* we are expecting the call back */ #define CALLBACK_DIALOUT 2 /* we are dialling out to call back */ /* * Variables set by command-line options. */ extern int debug; /* Debug flag */ extern int kdebugflag; /* Tell kernel to print debug messages */ extern int default_device; /* Using /dev/tty or equivalent */ extern char devnam[MAXPATHLEN]; /* Device name */ extern int crtscts; /* Use hardware flow control */ extern bool modem; /* Use modem control lines */ extern int inspeed; /* Input/Output speed requested */ extern u_int32_t netmask; /* IP netmask to set on interface */ extern bool lockflag; /* Create lock file to lock the serial dev */ extern bool nodetach; /* Don't detach from controlling tty */ extern bool updetach; /* Detach from controlling tty when link up */ extern char *initializer; /* Script to initialize physical link */ extern char *connect_script; /* Script to establish physical link */ extern char *disconnect_script; /* Script to disestablish physical link */ extern char *welcomer; /* Script to welcome client after connection */ extern char *ptycommand; /* Command to run on other side of pty */ extern int maxconnect; /* Maximum connect time (seconds) */ extern char user[MAXNAMELEN];/* Our name for authenticating ourselves */ extern char passwd[MAXSECRETLEN]; /* Password for PAP or CHAP */ extern bool auth_required; /* Peer is required to authenticate */ extern bool persist; /* Reopen link after it goes down */ extern bool uselogin; /* Use /etc/passwd for checking PAP */ extern char our_name[MAXNAMELEN];/* Our name for authentication purposes */ extern char remote_name[MAXNAMELEN]; /* Peer's name for authentication */ extern bool explicit_remote;/* remote_name specified with remotename opt */ extern bool demand; /* Do dial-on-demand */ extern char *ipparam; /* Extra parameter for ip up/down scripts */ extern bool cryptpap; /* Others' PAP passwords are encrypted */ extern int idle_time_limit;/* Shut down link if idle for this long */ extern int holdoff; /* Dead time before restarting */ extern bool holdoff_specified; /* true if user gave a holdoff value */ extern bool notty; /* Stdin/out is not a tty */ extern char *record_file; /* File to record chars sent/received */ extern bool sync_serial; /* Device is synchronous serial device */ extern int maxfail; /* Max # of unsuccessful connection attempts */ extern char linkname[MAXPATHLEN]; /* logical name for link */ extern bool tune_kernel; /* May alter kernel settings as necessary */ extern int connect_delay; /* Time to delay after connect script */ #ifdef PPP_FILTER extern struct bpf_program pass_filter; /* Filter for pkts to pass */ extern struct bpf_program active_filter; /* Filter for link-active pkts */ #endif #ifdef MSLANMAN extern bool ms_lanman; /* Use LanMan password instead of NT */ /* Has meaning only with MS-CHAP challenges */ #endif extern char *current_option; /* the name of the option being parsed */ extern int privileged_option; /* set iff the current option came from root */ extern char *option_source; /* string saying where the option came from */ /* * Values for phase. */ #define PHASE_DEAD 0 #define PHASE_INITIALIZE 1 #define PHASE_SERIALCONN 2 #define PHASE_DORMANT 3 #define PHASE_ESTABLISH 4 #define PHASE_AUTHENTICATE 5 #define PHASE_CALLBACK 6 #define PHASE_NETWORK 7 #define PHASE_RUNNING 8 #define PHASE_TERMINATE 9 #define PHASE_DISCONNECT 10 #define PHASE_HOLDOFF 11 /* * The following struct gives the addresses of procedures to call * for a particular protocol. */ struct protent { u_short protocol; /* PPP protocol number */ /* Initialization procedure */ void (*init) __P((int unit)); /* Process a received packet */ void (*input) __P((int unit, u_char *pkt, int len)); /* Process a received protocol-reject */ void (*protrej) __P((int unit)); /* Lower layer has come up */ void (*lowerup) __P((int unit)); /* Lower layer has gone down */ void (*lowerdown) __P((int unit)); /* Open the protocol */ void (*open) __P((int unit)); /* Close the protocol */ void (*close) __P((int unit, char *reason)); /* Print a packet in readable form */ int (*printpkt) __P((u_char *pkt, int len, void (*printer) __P((void *, char *, ...)), void *arg)); /* Process a received data packet */ void (*datainput) __P((int unit, u_char *pkt, int len)); bool enabled_flag; /* 0 iff protocol is disabled */ char *name; /* Text name of protocol */ char *data_name; /* Text name of corresponding data protocol */ option_t *options; /* List of command-line options */ /* Check requested options, assign defaults */ void (*check_options) __P((void)); /* Configure interface for demand-dial */ int (*demand_conf) __P((int unit)); /* Say whether to bring up link for this pkt */ int (*active_pkt) __P((u_char *pkt, int len)); }; /* Table of pointers to supported protocols */ extern struct protent *protocols[]; /* * Prototypes. */ /* Procedures exported from main.c. */ void die __P((int)); /* Cleanup and exit */ void quit __P((void)); /* like die(1) */ void novm __P((char *)); /* Say we ran out of memory, and die */ void ppptimeout __P((void (*func)(void *), void *arg, int t)); /* Call func(arg) after t seconds */ void untimeout __P((void (*func)(void *), void *arg)); /* Cancel call to func(arg) */ void update_link_stats __P((int)); /* Get stats at link termination */ void new_phase __P((int)); /* signal start of new phase */ /* Procedures exported from utils.c. */ void log_packet __P((u_char *, int, char *, int)); /* Format a packet and log it with syslog */ void print_string __P((void *, int, void (*) (void *, char *, ...), void *)); /* Format a string for output */ int slprintf __P((char *, int, char *, ...)); /* sprintf++ */ int vslprintf __P((char *, int, char *, va_list)); /* vsprintf++ */ size_t strlcpy __P((char *, const char *, size_t)); /* safe strcpy */ size_t strlcat __P((char *, const char *, size_t)); /* safe strncpy */ void pppd_dbglog __P((char *, ...)); /* log a debug message */ void pppd_info __P((char *, ...)); /* log an informational message */ void pppd_notice __P((char *, ...)); /* log a notice-level message */ void pppd_warn __P((char *, ...)); /* log a warning message */ void pppd_error __P((char *, ...)); /* log an error message */ void pppd_fatal __P((char *, ...)); /* log an error message and die(1) */ #define dbglog pppd_dbglog #define info pppd_info #define notice pppd_notice #define warn pppd_warn #define error pppd_error #define fatal pppd_fatal /* Procedures exported from auth.c */ void link_required __P((int)); /* we are starting to use the link */ void link_terminated __P((int)); /* we are finished with the link */ void link_down __P((int)); /* the LCP layer has left the Opened state */ void link_established __P((int)); /* the link is up; authenticate now */ void start_networks __P((void)); /* start all the network control protos */ void np_up __P((int, int)); /* a network protocol has come up */ void np_down __P((int, int)); /* a network protocol has gone down */ void np_finished __P((int, int)); /* a network protocol no longer needs link */ void auth_peer_fail __P((int, int)); /* peer failed to authenticate itself */ void auth_peer_success __P((int, int, char *, int)); /* peer successfully authenticated itself */ void auth_withpeer_fail __P((int, int)); /* we failed to authenticate ourselves */ void auth_withpeer_success __P((int, int)); /* we successfully authenticated ourselves */ int auth_check_options __P((void)); /* check authentication options supplied */ void auth_reset __P((int)); /* check what secrets we have */ int check_passwd __P((int, char *, int, char *, int, char **)); /* Check peer-supplied username/password */ int get_secret __P((int, char *, char *, char *, int *, int)); /* get "secret" for chap */ int auth_ip_addr __P((int, u_int32_t)); /* check if IP address is authorized */ int bad_ip_adrs __P((u_int32_t)); /* check if IP address is unreasonable */ /* Procedures exported from demand.c */ void demand_conf __P((void)); /* config interface(s) for demand-dial */ void demand_block __P((void)); /* set all NPs to queue up packets */ void demand_unblock __P((void)); /* set all NPs to pass packets */ void demand_discard __P((void)); /* set all NPs to discard packets */ void demand_rexmit __P((int)); /* retransmit saved frames for an NP */ int loop_chars __P((unsigned char *, int)); /* process chars from loopback */ int loop_frame __P((unsigned char *, int)); /* should we bring link up? */ /* Procedures exported from sys-*.c */ void sys_init __P((void)); /* Do system-dependent initialization */ void sys_cleanup __P((void)); /* Restore system state before exiting */ int sys_check_options __P((void)); /* Check options specified */ void sys_close __P((void)); /* Clean up in a child before execing */ int ppp_available __P((void)); /* Test whether ppp kernel support exists */ int get_pty __P((int *, int *, char *, int)); /* Get pty master/slave */ int open_ppp_loopback __P((void)); /* Open loopback for demand-dialling */ int establish_ppp __P((int)); /* Turn serial port into a ppp interface */ void restore_loop __P((void)); /* Transfer ppp unit back to loopback */ void disestablish_ppp __P((int)); /* Restore port to normal operation */ void clean_check __P((void)); /* Check if line was 8-bit clean */ void set_up_tty __P((int, int)); /* Set up port's speed, parameters, etc. */ void restore_tty __P((int)); /* Restore port's original parameters */ void setdtr __P((int, int)); /* Raise or lower port's DTR line */ void output __P((int, u_char *, int)); /* Output a PPP packet */ void wait_input __P((struct timeval *)); /* Wait for input, with timeout */ void ppp_delay __P((void)); /* delay task for a little while */ int read_packet __P((u_char *)); /* Read PPP packet */ int get_loop_output __P((void)); /* Read pkts from loopback */ void ppp_send_config __P((int, int, u_int32_t, int, int)); /* Configure i/f transmit parameters */ void ppp_set_xaccm __P((int, ext_accm)); /* Set extended transmit ACCM */ void ppp_recv_config __P((int, int, u_int32_t, int, int)); /* Configure i/f receive parameters */ int ccp_test __P((int, u_char *, int, int)); /* Test support for compression scheme */ void ccp_flags_set __P((int, int, int)); /* Set kernel CCP state */ int ccp_fatal_error __P((int)); /* Test for fatal decomp error in kernel */ int get_idle_time __P((int, struct ppp_idle *)); /* Find out how long link has been idle */ int get_ppp_stats __P((int, struct pppd_stats *)); /* Return link statistics */ int sifvjcomp __P((int, int, int, int)); /* Configure VJ TCP header compression */ int sifup __P((int)); /* Configure i/f up for one protocol */ int sifnpmode __P((int u, int proto, enum NPmode mode)); /* Set mode for handling packets for proto */ int sifdown __P((int)); /* Configure i/f down for one protocol */ int sifaddr __P((int, u_int32_t, u_int32_t, u_int32_t)); /* Configure IPv4 addresses for i/f */ int cifaddr __P((int, u_int32_t, u_int32_t)); /* Reset i/f IP addresses */ #ifdef INET6 int sif6addr __P((int, eui64_t, eui64_t)); /* Configure IPv6 addresses for i/f */ int cif6addr __P((int, eui64_t, eui64_t)); /* Remove an IPv6 address from i/f */ #endif int sifdefaultroute __P((int, u_int32_t, u_int32_t)); /* Create default route through i/f */ int cifdefaultroute __P((int, u_int32_t, u_int32_t)); /* Delete default route through i/f */ int sifproxyarp __P((int, u_int32_t)); /* Add proxy ARP entry for peer */ int cifproxyarp __P((int, u_int32_t)); /* Delete proxy ARP entry for peer */ u_int32_t GetMask __P((u_int32_t)); /* Get appropriate netmask for address */ int lock __P((char *)); /* Create lock file for device */ int relock __P((int)); /* Rewrite lock file with new pid */ void unlock __P((void)); /* Delete previously-created lock file */ void logwtmp __P((const char *, const char *, const char *)); /* Write entry to wtmp file */ int get_host_seed __P((void)); /* Get host-dependent random number seed */ int have_route_to __P((u_int32_t)); /* Check if route to addr exists */ #ifdef PPP_FILTER int set_filters __P((struct bpf_program *pass, struct bpf_program *active)); /* Set filter programs in kernel */ #endif #ifdef IPX_CHANGE int sipxfaddr __P((int, unsigned long, unsigned char *)); int cipxfaddr __P((int)); #endif /* Procedures exported from options.c */ int parse_args __P((int argc, char **argv)); /* Parse options from arguments given */ int options_from_file __P((char *filename, int must_exist, int check_prot, int privileged)); /* Parse options from an options file */ int options_from_user __P((void)); /* Parse options from user's .ppprc */ int options_for_tty __P((void)); /* Parse options from /etc/ppp/options.tty */ int options_from_list __P((struct wordlist *, int privileged)); /* Parse options from a wordlist */ int getword __P((FILE *f, char *word, int *newlinep, char *filename)); /* Read a word from a file */ void option_error __P((char *fmt, ...)); /* Print an error message about an option */ int int_option __P((char *, int *)); /* Simplified number_option for decimal ints */ void add_options __P((option_t *)); /* Add extra options */ /* * This structure is used to store information about certain * options, such as where the option value came from (/etc/ppp/options, * command line, etc.) and whether it came from a privileged source. */ struct option_info { int priv; /* was value set by sysadmin? */ char *source; /* where option came from */ }; extern struct option_info devnam_info; extern struct option_info initializer_info; extern struct option_info connect_script_info; extern struct option_info disconnect_script_info; extern struct option_info welcomer_info; extern struct option_info ptycommand_info; /* * Hooks to enable plugins to change various things. */ extern int (*new_phase_hook) __P((int)); extern int (*idle_time_hook) __P((struct ppp_idle *)); extern int (*holdoff_hook) __P((void)); extern int (*pap_check_hook) __P((void)); extern int (*pap_auth_hook) __P((char *user, char *passwd/*, char **msgp, struct wordlist **paddrs, struct wordlist **popts*/)); extern void (*pap_logout_hook) __P((void)); extern int (*pap_passwd_hook) __P((char *user, char *passwd)); extern void (*ip_up_hook) __P((void)); extern void (*ip_down_hook) __P((void)); extern void (*auth_linkup_hook) __P((void)); extern void (*auth_linkdown_hook) __P((void)); /* * Inline versions of get/put char/short/long. * Pointer is advanced; we assume that both arguments * are lvalues and will already be in registers. * cp MUST be u_char *. */ #define GETCHAR(c, cp) { \ (c) = *(cp)++; \ } #define PUTCHAR(c, cp) { \ *(cp)++ = (u_char) (c); \ } #define GETSHORT(s, cp) { \ (s) = *(cp)++ << 8; \ (s) |= *(cp)++; \ } #define PUTSHORT(s, cp) { \ *(cp)++ = (u_char) ((s) >> 8); \ *(cp)++ = (u_char) (s); \ } #define GETLONG(l, cp) { \ (l) = *(cp)++ << 8; \ (l) |= *(cp)++; (l) <<= 8; \ (l) |= *(cp)++; (l) <<= 8; \ (l) |= *(cp)++; \ } #define PUTLONG(l, cp) { \ *(cp)++ = (u_char) ((l) >> 24); \ *(cp)++ = (u_char) ((l) >> 16); \ *(cp)++ = (u_char) ((l) >> 8); \ *(cp)++ = (u_char) (l); \ } #define INCPTR(n, cp) ((cp) += (n)) #define DECPTR(n, cp) ((cp) -= (n)) /* * System dependent definitions for user-level 4.3BSD UNIX implementation. */ #define TIMEOUT(r, f, t) ppptimeout((r), (f), (t)) #define UNTIMEOUT(r, f) untimeout((r), (f)) #define BCOPY(s, d, l) memcpy(d, s, l) #define BZERO(s, n) memset(s, 0, n) #define PRINTMSG(m, l) { info("Remote message: %0.*v", l, m); } /* * MAKEHEADER - Add Header fields to a packet. */ #define MAKEHEADER(p, t) { \ PUTCHAR(PPP_ALLSTATIONS, p); \ PUTCHAR(PPP_UI, p); \ PUTSHORT(t, p); } /* * Exit status values. */ #define EXIT_OK 0 #define EXIT_FATAL_ERROR 1 #define EXIT_OPTION_ERROR 2 #define EXIT_NOT_ROOT 3 #define EXIT_NO_KERNEL_SUPPORT 4 #define EXIT_USER_REQUEST 5 #define EXIT_LOCK_FAILED 6 #define EXIT_OPEN_FAILED 7 #define EXIT_CONNECT_FAILED 8 #define EXIT_PTYCMD_FAILED 9 #define EXIT_NEGOTIATION_FAILED 10 #define EXIT_PEER_AUTH_FAILED 11 #define EXIT_IDLE_TIMEOUT 12 #define EXIT_CONNECT_TIME 13 #define EXIT_CALLBACK 14 #define EXIT_PEER_DEAD 15 #define EXIT_HANGUP 16 #define EXIT_LOOPBACK 17 #define EXIT_INIT_FAILED 18 #define EXIT_AUTH_TOPEER_FAILED 19 /* * Debug macros. Slightly useful for finding bugs in pppd, not particularly * useful for finding out why your connection isn't being established. */ #ifdef DEBUGALL #define DEBUGMAIN 1 #define DEBUGFSM 1 #define DEBUGLCP 1 #define DEBUGIPCP 1 #define DEBUGIPV6CP 1 #define DEBUGUPAP 1 #define DEBUGCHAP 1 #endif #define DEBUGMAIN 1 #define DEBUGUPAP 1 #define DEBUGCHAP 1 #ifdef DEBUGMAIN #define MAINDEBUG(x) if (debug) dbglog x #else #define MAINDEBUG(x) #endif #ifdef DEBUGSYS #define SYSDEBUG(x) if (debug) dbglog x #else #define SYSDEBUG(x) #endif #ifdef DEBUGFSM #define FSMDEBUG(x) if (debug) dbglog x #else #define FSMDEBUG(x) #endif #ifdef DEBUGLCP #define LCPDEBUG(x) if (debug) dbglog x #else #define LCPDEBUG(x) #endif #ifdef DEBUGIPCP #define IPCPDEBUG(x) if (debug) dbglog x #else #define IPCPDEBUG(x) #endif #ifdef DEBUGIPV6CP #define IPV6CPDEBUG(x) if (debug) dbglog x #else #define IPV6CPDEBUG(x) #endif #ifdef DEBUGUPAP #define UPAPDEBUG(x) if (debug) dbglog x #else #define UPAPDEBUG(x) #endif #ifdef DEBUGCHAP #define CHAPDEBUG(x) if (debug) dbglog x #else #define CHAPDEBUG(x) #endif #ifdef DEBUGIPXCP #define IPXCPDEBUG(x) if (debug) dbglog x #else #define IPXCPDEBUG(x) #endif #ifndef SIGTYPE #if defined(sun) || defined(SYSV) || defined(POSIX_SOURCE) #define SIGTYPE void #else #define SIGTYPE int #endif /* defined(sun) || defined(SYSV) || defined(POSIX_SOURCE) */ #endif /* SIGTYPE */ #ifndef MIN #define MIN(a, b) ((a) < (b)? (a): (b)) #endif #ifndef MAX #define MAX(a, b) ((a) > (b)? (a): (b)) #endif #endif /* __PPP_H__ */