irdpd.c

操作系统源代码

	/* We don't care about RIP packets when there are router adverts. */
	if (now + MaxAdvertisementInterval < router_advert_valid) return;

	udp_io_hdr= (udp_io_hdr_t *) rip_buf;
	if (udp_io_hdr->uih_data_len != n - sizeof(*udp_io_hdr)) {
		if (debug) printf("Bad sized route packet (discarded)\n");
		return;
	}
	routeinfo= (routeinfo_t *) (rip_buf + sizeof(*udp_io_hdr)
			+ udp_io_hdr->uih_ip_opt_len);

	if (routeinfo->version != RIP_VERSION
				|| routeinfo->command != RIP_REPLY) {
		if (debug) {
			printf("Route packet command %d, version %d ignored\n",
				routeinfo->command, routeinfo->version);
		}
		return;
	}

	/* Look for a default route, the route to the gateway. */
	end= (struct routedata *) (rip_buf + n);
	default_dist= (u32_t) -1;
	for (data= routeinfo->data; data < end; data++) {
		if (ntohs(data->family) != AF_INET || data->ip_addr != 0)
			continue;
		default_dist= ntohl(data->metric);
		if (default_dist >= 256) {
			if (debug) printf("Strange metric %d\n", default_dist);
		}
	}
	pref= default_dist >= 256 ? 1 : 512 - default_dist;
	pref+= priority_offset;

	/* Add the gateway to the table with the calculated preference. */
	add_gateway(udp_io_hdr->uih_src_addr, pref);

	if (debug) {
		printf("Routing table after RIP packet from %s:\n",
			addr2name(udp_io_hdr->uih_src_addr));
		print_table();
	}

	/* Start advertizing. */
	if (next_advert == NEVER) next_advert= IMMEDIATELY;
}

void irdp_incoming(ssize_t n)
/* Look for router solicitations and router advertisements.  The solicitations
 * are probably from other irdpd daemons, we answer them if we do not expect
 * a real router to answer.  The advertisements cause this daemon to shut up.
 */
{
	ip_hdr_t *ip_hdr;
	icmp_hdr_t *icmp_hdr;
	int ip_hdr_len;
	char *data;
	int i;
	int router;
	ipaddr_t addr;
	i32_t pref;
	time_t valid;

	ip_hdr= (ip_hdr_t *) irdp_buf;
	ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) << 2;
	if (n < ip_hdr_len + 8) {
		if (debug) printf("Bad sized ICMP (discarded)\n");
		return;
	}

	icmp_hdr= (icmp_hdr_t *)(irdp_buf + ip_hdr_len);

	/* Did I send it myself? */
	if (ip_hdr->ih_src == my_ip_addr) return;
	if ((htonl(ip_hdr->ih_src) & 0xFF000000L) == 0x7F000000L) return;

	if (icmp_hdr->ih_type == ICMP_TYPE_ROUTE_SOL) {
		/* Some other host is looking for a router.  Send a table
		 * if there is no smart router around, we are not still
		 * solicitating ourselves, and we are not told to be silent.
		 */
		if (sol_retries == 0 && table_size > 0
				&& now > router_advert_valid && !silent) {
			advertize(ip_hdr->ih_src);
		}
		return;
	}
	if (icmp_hdr->ih_type != ICMP_TYPE_ROUTER_ADVER) return;

	/* Incoming router advertisement, the kind of packet the TCP/IP task
	 * is very happy with.  No need to solicit further.
	 */
	sol_retries= 0;

	/* Add router info to our table.  Also see if the packet came from
	 * a router, and not another irdpd.  If it is from a router then we
	 * go silent for the lifetime of the ICMP.
	 */
	router= 0;
	data= (char *) icmp_hdr->ih_dun.uhd_data;
	for (i= 0; i < icmp_hdr->ih_hun.ihh_ram.iram_na; i++) {
		addr= * (ipaddr_t *) data;
		data+= sizeof(ipaddr_t);
		pref= htonl(* (i32_t *) data);
		data+= sizeof(i32_t);

		if (addr == ip_hdr->ih_src) {
			/* The sender is in the routing table! */
			router= 1;
		}
		add_gateway(addr, pref);
	}

	valid= now + ntohs(icmp_hdr->ih_hun.ihh_ram.iram_lt);
	if (router) router_advert_valid= valid;

	/* Restart advertizing close to the timeout of the advert.  (No more
	 * irdpd adverts if the router stays alive.)
	 */
	if (router || next_advert > valid - DANGER)
		next_advert= valid - DANGER;

	if (debug) {
		printf("Routing table after advert received from %s:\n",
			addr2name(ip_hdr->ih_src));
		print_table();
		if (router) {
			struct tm *tm= localtime(&router_advert_valid);
			printf(
			"This router advert is valid until %02d:%02d:%02d\n",
				tm->tm_hour, tm->tm_min, tm->tm_sec);
		}
	}
}

void sig_handler(int sig)
/* A signal changes the debug level. */
{
	switch (sig) {
	case SIGUSR1:	debug++;		break;
	case SIGUSR2:	debug= 0;		break;
	}
}

void usage(void)
{
	fprintf(stderr,
"Usage: irdpd [-d] [-U udp-device] [-I ip-device] [-o priority-offset]\n");
	exit(1);
}

int main(int argc, char **argv)
{
	int i;
	struct servent *service;
	udpport_t route_port;
	nwio_udpopt_t udpopt;
	nwio_ipconf_t ipconf;
	nwio_ipopt_t ipopt;
	asynchio_t asyn;
	time_t timeout;
	struct timeval tv;
	struct sigaction sa;
	char *offset_arg, *offset_end;
	long arg;

	udp_device = ip_device = nil;

	for (i = 1; i < argc && argv[i][0] == '-'; i++) {
		char *p= argv[i] + 1;

		if (p[0] == '-' && p[1] == 0) { i++; break; }

		while (*p != 0) {
			switch (*p++) {
			case 'U':
				if (udp_device != nil) usage();
				if (*p == 0) {
					if (++i == argc) usage();
					p= argv[i];
				}
				udp_device= p;
				p= "";
				break;
			case 'I':
				if (ip_device != nil) usage();
				if (*p == 0) {
					if (++i == argc) usage();
					p= argv[i];
				}
				ip_device= p;
				p= "";
				break;
			case 'o':
				if (offset_arg != nil) usage();
				if (*p == 0) {
					if (++i == argc) usage();
					p= argv[i];
				}
				offset_arg= p;
				p= "";
				break;
			case 'b':
				bcast= 1;
				break;
			case 's':
				silent= 1;
				break;
			case 'd':
				debug= 1;
				break;
			default:
				usage();
			}
		}
	}
	if (i != argc) usage();

	/* Debug level signals. */
	sa.sa_handler= sig_handler;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags= 0;
	sigaction(SIGUSR1, &sa, nil);
	sigaction(SIGUSR2, &sa, nil);

	if (udp_device == nil && (udp_device= getenv("UDP_DEVICE")) == nil)
		udp_device= UDP_DEVICE;

	if (ip_device == nil && (ip_device= getenv("IP_DEVICE")) == nil)
		ip_device= IP_DEVICE;

	if (offset_arg == nil) {
		priority_offset= PRIO_OFF_DEF;
	} else {
		arg= strtol(offset_arg, &offset_end, 0);
		if (*offset_end != 0 || (priority_offset= arg) != arg) usage();
	}

	if ((service= getservbyname("route", "udp")) == nil) {
		fprintf(stderr,
	"irdpd: unable to look up the port number for the 'route' service\n");
		exit(1);
	}

	route_port= (udpport_t) service->s_port;

	if ((rip_fd= open(udp_device, O_RDWR)) < 0) fatal(udp_device);

	udpopt.nwuo_flags= NWUO_COPY | NWUO_LP_SET | NWUO_DI_LOC
		| NWUO_EN_BROAD | NWUO_RP_SET | NWUO_RA_ANY | NWUO_RWDATALL
		| NWUO_DI_IPOPT;
	udpopt.nwuo_locport= route_port;
	udpopt.nwuo_remport= route_port;
	if (ioctl(rip_fd, NWIOSUDPOPT, &udpopt) < 0)
		fatal("setting UDP options failed");

	if ((irdp_fd= open(ip_device, O_RDWR)) < 0) fatal(ip_device);

	if (ioctl(irdp_fd, NWIOGIPCONF, &ipconf) < 0)
		fatal("can't get IP configuration");

	my_ip_addr= ipconf.nwic_ipaddr;

	ipopt.nwio_flags= NWIO_COPY | NWIO_EN_LOC | NWIO_EN_BROAD
			| NWIO_REMANY | NWIO_PROTOSPEC
			| NWIO_HDR_O_SPEC | NWIO_RWDATALL;
	ipopt.nwio_tos= 0;
	ipopt.nwio_ttl= 255;
	ipopt.nwio_df= 0;
	ipopt.nwio_hdropt.iho_opt_siz= 0;
	ipopt.nwio_rem= HTONL(0xFFFFFFFFL);
	ipopt.nwio_proto= IPPROTO_ICMP;

	if (ioctl(irdp_fd, NWIOSIPOPT, &ipopt) < 0)
		fatal("can't configure ICMP channel");

	asyn_init(&asyn);

	while (1) {
		ssize_t r;

		if (do_rip) {
			/* Try a RIP read. */
			r= asyn_read(&asyn, rip_fd, rip_buf, sizeof(rip_buf));
			if (r < 0) {
				if (errno == EIO) fatal(udp_device);
				if (errno != EINPROGRESS) report(udp_device);
			} else {
				now= time(nil);
				rip_incoming(r);
			}
		}

		if (do_rdisc) {
			/* Try an IRDP read. */
			r= asyn_read(&asyn, irdp_fd, irdp_buf,
							sizeof(irdp_buf));
			if (r < 0) {
				if (errno == EIO) fatal(ip_device);
				if (errno != EINPROGRESS) report(ip_device);
			} else {
				now= time(nil);
				irdp_incoming(r);
			}
		}
		fflush(stdout);

		/* Compute the next wakeup call. */
		timeout= next_sol < next_advert ? next_sol : next_advert;

		/* Wait for a RIP or IRDP packet or a timeout. */
		tv.tv_sec= timeout;
		tv.tv_usec= 0;
		if (asyn_wait(&asyn, 0, timeout == NEVER ? nil : &tv) < 0) {
			/* Timeout? */
			if (errno != EINTR && errno != EAGAIN)
				fatal("asyn_wait()");
			now= time(nil);
			time_functions();
		}
	}
}