irdpd.c

操作系统源代码

/*	irdpd 1.8 - Internet router discovery protocol daemon.
 *							Author: Kees J. Bot
 *								28 May 1994
 * Activily solicitate or passively look for routers.
 * Based heavily on its forerunners, the irdp_sol and rip2icmp daemons by
 * Philip Homburg.
 */
#define nil 0
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <limits.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <sys/asynchio.h>
#include <net/hton.h>
#include <net/netlib.h>
#include <net/gen/in.h>
#include <net/gen/ip_hdr.h>
#include <net/gen/icmp.h>
#include <net/gen/icmp_hdr.h>
#include <net/gen/ip_io.h>
#include <net/gen/inet.h>
#include <net/gen/netdb.h>
#include <net/gen/oneCsum.h>
#include <net/gen/socket.h>
#include <net/gen/udp.h>
#include <net/gen/udp_hdr.h>
#include <net/gen/udp_io.h>

#define MAX_RETRIES		    5	/* # router solicitations. */
#define TIMEOUT			    4	/* Secs between solicitate retries. */
#define DEST_TO 	      (10*60)	/* 10 minutes */
#define NEW_ROUTE	       (5*60)	/* 5 minutes */
#define DANGER		       (2*60)	/* Nearing a advert timeout? */
#define DEAD_TO		    (24L*60*60)	/* 24 hours */
#define DEAD_PREF	    0x80000000L	/* from RFC 1236 */
#define MaxAdvertisementInterval  450	/* 7.5 minutes */
#define LifeTime		(4 * MaxAdvertisementInterval)
#define PRIO_OFF_DEF		-1024
#define RIP_VERSION		    1
#define RIP_REPLY		    2

/* It's now or never. */
#define IMMEDIATELY	((time_t) ((time_t) -1 < 0 ? LONG_MIN : 0))
#define NEVER		((time_t) ((time_t) -1 < 0 ? LONG_MAX : ULONG_MAX))

#if !DEBUG
/* Unless doing serious debugging. */
#define gethostbyaddr(addr, len, type)	((struct hostent *) nil)
#endif

#if !__minix_vmd
/* Standard Minix needs to choose between router discovery and RIP info. */
int do_rdisc= 1;
int do_rip= 0;
#else
/* VMD Minix can do both at once. */
#define do_rdisc 1
#define do_rip 1
#endif

int rip_fd;			/* For incoming RIP packet. */
int irdp_fd;			/* Receive or transmit IRDP packets. */

char *udp_device;		/* UDP device to use. */
char *ip_device;		/* IP device to use. */

int priority_offset;		/* Offset to make my routes less preferred. */

int bcast= 0;			/* Broadcast adverts to all. */
int silent= 0;			/* Don't react to solicitations. */
int debug= 0;

char rip_buf[8192];		/* Incoming RIP packet buffer. */
char irdp_buf[1024];		/* IRDP buffer. */

typedef struct routeinfo
{
	u8_t		command;
	u8_t		version;
	u16_t		zero1;
	struct routedata {
		u16_t	family;
		u16_t	zero2;
		u32_t	ip_addr;
		u32_t	zero3, zero4;
		u32_t	metric;
	} data[1];
} routeinfo_t;

typedef struct table
{
	ipaddr_t	tab_gw;
	i32_t		tab_pref;
	time_t		tab_time;
} table_t;

table_t *table;			/* Collected table of routing info. */
size_t table_size;

ipaddr_t my_ip_addr;		/* IP address of the local host. */

int sol_retries= MAX_RETRIES;
time_t next_sol= IMMEDIATELY;
time_t next_advert= NEVER;
time_t router_advert_valid= IMMEDIATELY;
time_t now;

void report(const char *label)
/* irdpd: /dev/hd0: Device went up in flames */
{
	fprintf(stderr, "irdpd: %s: %s\n", label, strerror(errno));
}

void fatal(const char *label)
/* irdpd: /dev/house: Taking this with it */
{
	report(label);
	exit(1);
}

char *addr2name(ipaddr_t host)
/* Translate an IP address to a printable name. */
{
#if DEBUG
	struct hostent *hostent;

	hostent= gethostbyaddr((char *) &host, sizeof(host), AF_INET);
	return hostent == nil ? inet_ntoa(host) : hostent->h_name;
#else
	return inet_ntoa(host);
#endif
}

void print_table(void)
/* Show the collected routing table. */
{
	int i;
	table_t *ptab;
	struct tm *tm;

	for (i= 0, ptab= table; i < table_size; i++, ptab++) {
		if (ptab->tab_time < now - DEAD_TO) continue;

		tm= localtime(&ptab->tab_time);
		printf("%-40s %6ld %02d:%02d:%02d\n",
			addr2name(ptab->tab_gw),
			(long) ptab->tab_pref,
			tm->tm_hour, tm->tm_min, tm->tm_sec);
	}
}

void advertize(ipaddr_t host)
/* Send a router advert to a host. */
{
	char *buf, *data;
	ip_hdr_t *ip_hdr;
	icmp_hdr_t *icmp_hdr;
	int i;
	table_t *ptab;

	buf= malloc(sizeof(*ip_hdr) + offsetof(icmp_hdr_t, ih_dun.uhd_data)
			+ table_size * (sizeof(ipaddr_t) + sizeof(u32_t)));
	if (buf == nil) fatal("heap error");

	ip_hdr= (ip_hdr_t *) buf;
	icmp_hdr= (icmp_hdr_t *) (ip_hdr + 1);

	ip_hdr->ih_vers_ihl= 0x45;
	ip_hdr->ih_dst= host;

	icmp_hdr->ih_type= ICMP_TYPE_ROUTER_ADVER;
	icmp_hdr->ih_code= 0;
	icmp_hdr->ih_hun.ihh_ram.iram_na= 0;
	icmp_hdr->ih_hun.ihh_ram.iram_aes= 2;
	icmp_hdr->ih_hun.ihh_ram.iram_lt= htons(LifeTime);
	data= (char *) icmp_hdr->ih_dun.uhd_data;

	/* Collect gateway entries from the table. */
	for (i= 0, ptab= table; i < table_size; i++, ptab++) {
		if (ptab->tab_time < now - DEAD_TO) continue;

		icmp_hdr->ih_hun.ihh_ram.iram_na++;
		if (ptab->tab_time < now - DEST_TO) ptab->tab_pref= DEAD_PREF;
		* (ipaddr_t *) data= ptab->tab_gw;
		data+= sizeof(ipaddr_t);
		* (i32_t *) data= htonl(ptab->tab_pref);
		data+= sizeof(i32_t);
	}
	icmp_hdr->ih_chksum= 0;
	icmp_hdr->ih_chksum= ~oneC_sum(0, icmp_hdr, data - (char *) icmp_hdr);

	if (icmp_hdr->ih_hun.ihh_ram.iram_na > 0) {
		/* Send routing info. */

		if (debug) {
			printf("Routing table send to %s:\n", addr2name(host));
			print_table();
		}

		if (write(irdp_fd, buf, data - buf) < 0) {
			(errno == EIO ? fatal : report)(ip_device);
		}
	}
	free(buf);
}

void time_functions(void)
/* Perform time dependend functions: router solicitation, router advert. */
{
	if (now >= next_sol) {
		char buf[sizeof(ip_hdr_t) + 8];
		ip_hdr_t *ip_hdr;
		icmp_hdr_t *icmp_hdr;

		if (sol_retries == 0) {
			/* Stop solicitating. */
			next_sol= NEVER;
#if !__minix_vmd
			/* Switch to RIP if no router responded. */
			if (table_size == 0) {
				do_rip= 1;
				do_rdisc= 0;
			}
#endif
			return;
		}

		/* Broadcast a router solicitation to find a router. */
		ip_hdr= (ip_hdr_t *) buf;
		icmp_hdr= (icmp_hdr_t *) (ip_hdr + 1);

		ip_hdr->ih_vers_ihl= 0x45;
		ip_hdr->ih_dst= HTONL(0xFFFFFFFFL);

		icmp_hdr->ih_type= ICMP_TYPE_ROUTE_SOL;
		icmp_hdr->ih_code= 0;
		icmp_hdr->ih_chksum= 0;
		icmp_hdr->ih_hun.ihh_unused= 0;
		icmp_hdr->ih_chksum= ~oneC_sum(0, icmp_hdr, 8);

		if (debug) printf("Broadcasting router solicitation\n");

		if (write(irdp_fd, buf, sizeof(buf)) < 0)
			fatal("sending router solicitation failed");

		/* Schedule the next packet. */
		next_sol= now + TIMEOUT;

		sol_retries--;
	}

	if (now >= next_advert) {
		/* Advertize routes to the local host (normally), or
		 * broadcast them (to keep bad hosts up.)
		 */

		advertize(bcast ? HTONL(0xFFFFFFFFL) : HTONL(0x7F000001L));
		next_advert= now + MaxAdvertisementInterval;
#if !__minix_vmd
		/* Make sure we are listening to RIP now. */
		do_rip= 1;
		do_rdisc= 0;
#endif
	}
}

void add_gateway(ipaddr_t host, i32_t pref)
/* Add a router with given address and preference to the routing table. */
{
	table_t *oldest, *ptab;
	int i;

	/* Look for the host, or select the oldest entry. */
	oldest= nil;
	for (i= 0, ptab= table; i < table_size; i++, ptab++) {
		if (ptab->tab_gw == host) break;

		if (oldest == nil || ptab->tab_time < oldest->tab_time)
			oldest= ptab;
	}

	/* Don't evict the oldest if it is still valid. */
	if (oldest != nil && oldest->tab_time >= now - DEST_TO) oldest= nil;

	/* Expand the table? */
	if (i == table_size && oldest == nil) {
		table_size++;
		table= realloc(table, table_size * sizeof(*table));
		if (table == nil) fatal("heap error");
		oldest= &table[table_size - 1];
	}

	if (oldest != nil) {
		ptab= oldest;
		ptab->tab_gw= host;
		ptab->tab_pref= DEAD_PREF;
	}

	/* Replace an entry if the new one looks more promising. */
	if (pref >= ptab->tab_pref || ptab->tab_time <= now - NEW_ROUTE) {
		ptab->tab_pref= pref;
		ptab->tab_time= now;
	}
}

void rip_incoming(ssize_t n)
/* Use a RIP packet to add to the router table.  (RIP packets are really for
 * between routers, but often it is the only information around.)
 */
{
	udp_io_hdr_t *udp_io_hdr;
	u32_t default_dist;
	i32_t pref;
	routeinfo_t *routeinfo;
	struct routedata *data, *end;