llc_subr.c

早期freebsd实现

/* 
 * Copyright (C) Dirk Husemann, Computer Science Department IV, 
 * 		 University of Erlangen-Nuremberg, Germany, 1990, 1991, 1992
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 * 
 * This code is derived from software contributed to Berkeley by
 * Dirk Husemann and the Computer Science Department (IV) of
 * the University of Erlangen-Nuremberg, Germany.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)llc_subr.c	8.1 (Berkeley) 6/10/93
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_llc.h>
#include <net/route.h>

#include <netccitt/dll.h>
#include <netccitt/llc_var.h>

/*
 * Frame names for diagnostic messages
 */
char *frame_names[] = { "INFO", "RR", "RNR", "REJ", "DM", "SABME", "DISC",
	"UA", "FRMR", "UI", "XID", "TEST", "ILLEGAL", "TIMER", "N2xT1"};


/*
 * Trace level
 */
int llc_tracelevel = LLCTR_URGENT;

/*
 * Values for accessing various bitfields
 */
struct bitslice llc_bitslice[] = {
/*	  mask, shift value */
	{ 0x1,  0x0 },
	{ 0xfe, 0x1 },
	{ 0x3,  0x0 },
	{ 0xc,  0x2 },
	{ 0x10, 0x4 },
	{ 0xe0, 0x5 },
	{ 0x1f, 0x0 }
};

/*
 * We keep the link control blocks on a doubly linked list - 
 * primarily for checking in llc_time() 
 */

struct llccb_q llccb_q = { &llccb_q, &llccb_q };

/*
 * Flag for signalling wether route tree for AF_LINK has been
 * initialized yet.
 */

int af_link_rts_init_done = 0; 


/*
 * Functions dealing with struct sockaddr_dl */

/* Compare sdl_a w/ sdl_b */

sdl_cmp(struct sockaddr_dl *sdl_a, struct sockaddr_dl *sdl_b)
{
	if (LLADDRLEN(sdl_a) != LLADDRLEN(sdl_b))
		return(1);
	return(bcmp((caddr_t) sdl_a->sdl_data, (caddr_t) sdl_b->sdl_data,
		    LLADDRLEN(sdl_a)));
}

/* Copy sdl_f to sdl_t */

sdl_copy(struct sockaddr_dl *sdl_f, struct sockaddr_dl *sdl_t)
{
	bcopy((caddr_t) sdl_f, (caddr_t) sdl_t, sdl_f->sdl_len);
}

/* Swap sdl_a w/ sdl_b */

sdl_swapaddr(struct sockaddr_dl *sdl_a, struct sockaddr_dl *sdl_b)
{
	struct sockaddr_dl sdl_tmp;

	sdl_copy(sdl_a, &sdl_tmp); 
	sdl_copy(sdl_b, sdl_a); 
	sdl_copy(&sdl_tmp, sdl_b);
}

/* Fetch the sdl of the associated if */

struct sockaddr_dl * 
sdl_getaddrif(struct ifnet *ifp)
{
	register struct ifaddr *ifa;

	for(ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next) 	
		if (ifa->ifa_addr->sa_family == AF_LINK ) 		
			return((struct sockaddr_dl *)(ifa->ifa_addr));

	return((struct sockaddr_dl *)0);
}

/* Check addr of interface with the one given */

sdl_checkaddrif(struct ifnet *ifp, struct sockaddr_dl *sdl_c)
{
	register struct ifaddr *ifa;

	for(ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next) 	
		if ((ifa->ifa_addr->sa_family == AF_LINK ) && 	 
		    !sdl_cmp((struct sockaddr_dl *)(ifa->ifa_addr), sdl_c))
			return(1);
	
	return(0);
}

/* Build an sdl from MAC addr, DLSAP addr, and interface */

sdl_setaddrif(struct ifnet *ifp, u_char *mac_addr, u_char dlsap_addr, 
	      u_char mac_len, struct sockaddr_dl *sdl_to)
{
	register struct sockaddr_dl *sdl_tmp;

	if ((sdl_tmp = sdl_getaddrif(ifp)) ) { 	
		sdl_copy(sdl_tmp, sdl_to); 	
		bcopy((caddr_t) mac_addr, (caddr_t) LLADDR(sdl_to), mac_len);
		*(LLADDR(sdl_to)+mac_len) = dlsap_addr;
		sdl_to->sdl_alen = mac_len+1; 	
		return(1); 
	} else return(0);
}

/* Fill out the sdl header aggregate */

sdl_sethdrif(struct ifnet *ifp, u_char *mac_src, u_char dlsap_src, u_char *mac_dst,
	     u_char dlsap_dst, u_char mac_len, struct sdl_hdr *sdlhdr_to)
{
	if ( !sdl_setaddrif(ifp, mac_src, dlsap_src, mac_len,
			     &sdlhdr_to->sdlhdr_src) ||
	     !sdl_setaddrif(ifp, mac_dst, dlsap_dst, mac_len,
			     &sdlhdr_to->sdlhdr_dst) )
		return(0);
	else return(1);
}

static struct sockaddr_dl sap_saddr; 
static struct sockaddr_dl sap_sgate = {
	sizeof(struct sockaddr_dl), /* _len */ 
	AF_LINK                     /* _af */
};

/*
 * Set sapinfo for SAP address, llcconfig, af, and interface
 */
struct npaidbentry *
llc_setsapinfo(struct ifnet *ifp, u_char af, u_char sap, struct dllconfig *llconf)
{
	struct protosw *pp; 
	struct sockaddr_dl *ifdl_addr; 
	struct rtentry *sirt = (struct rtentry *)0; 
	struct npaidbentry *sapinfo; 
	u_char saploc; 
	int size = sizeof(struct npaidbentry);

	USES_AF_LINK_RTS;

	/* 
	 * We rely/assume that only STREAM protocols will make use of 
	 * connection oriented LLC2. If this will one day not be the 
	 * case this will obviously fail. 
	 */ 
	pp = pffindtype (af, SOCK_STREAM); 
	if (pp == 0 || pp->pr_input == 0 || pp->pr_ctlinput == 0) { 	
		printf("network	level protosw error"); 	
		return 0; 
	}

	/*
	 * We need a way to jot down the LLC2 configuration for
	 * a certain LSAP address. To do this we enter 
	 * a "route" for the SAP.
	 */
	ifdl_addr = sdl_getaddrif(ifp);
	sdl_copy(ifdl_addr, &sap_saddr); 
	sdl_copy(ifdl_addr, &sap_sgate);
	saploc = LLSAPLOC(&sap_saddr, ifp); 
	sap_saddr.sdl_data[saploc] = sap;
	sap_saddr.sdl_alen++;

	/* now enter it */ 
	rtrequest(RTM_ADD, (struct sockaddr *)&sap_saddr,
			(struct sockaddr *)&sap_sgate, 0, 0, &sirt); 
	if (sirt == 0) 	
		return 0;

	/* Plug in config information in rt->rt_llinfo */

	sirt->rt_llinfo = malloc(size , M_PCB, M_WAITOK); 
	sapinfo = (struct npaidbentry *) sirt->rt_llinfo; 
	if (sapinfo) { 	
		bzero ((caddr_t)sapinfo, size); 	
		/* 	 
		 * For the time being we support LLC CLASS II here 	 
		 * only 	 
		 */ 	
		sapinfo->si_class = LLC_CLASS_II; 	
		sapinfo->si_window = llconf->dllcfg_window;
		sapinfo->si_trace = llconf->dllcfg_trace; 	
		if (sapinfo->si_trace)
			llc_tracelevel--;
		else llc_tracelevel++;
		sapinfo->si_input = pp->pr_input; 	
		sapinfo->si_ctlinput = (caddr_t (*)())pp->pr_ctlinput;

		return (sapinfo);
	}

	return 0;
}

/*
 * Get sapinfo for SAP address and interface 
 */
struct npaidbentry *
llc_getsapinfo(u_char sap, struct ifnet *ifp)
{
	struct sockaddr_dl *ifdl_addr; 
	struct sockaddr_dl si_addr; 
	struct rtentry *sirt; 
	u_char saploc;

	USES_AF_LINK_RTS;

	ifdl_addr = sdl_getaddrif(ifp); 
	sdl_copy(ifdl_addr, &si_addr); 
	saploc = LLSAPLOC(&si_addr, ifp); 
	si_addr.sdl_data[saploc] = sap;
	si_addr.sdl_alen++;

	if ((sirt = rtalloc1((struct sockaddr *)&si_addr, 0))) 	
		sirt->rt_refcnt--; 
	else return(0);

	return((struct npaidbentry *)sirt->rt_llinfo);
}

/*
 * llc_seq2slot() --- We only allocate enough memory to hold the window. This
 * introduces the necessity to keep track of two ``pointers''
 *
 *        o llcl_freeslot     the next free slot to be used
 *                            this one advances modulo llcl_window
 *        o llcl_projvs       the V(S) associated with the next frame
 *                            to be set via llcl_freeslot
 *                            this one advances modulo LLC_MAX_SEQUENCE
 *
 * A new frame is inserted at llcl_output_buffers[llcl_freeslot], after
 * which both llcl_freeslot and llcl_projvs are incremented.
 *
 * The slot sl(sn) for any given sequence number sn is given by
 *
 *        sl(sn) = (llcl_freeslot + llcl_window - 1 - (llcl_projvs +
 *                  LLC_MAX_SEQUENCE- sn) % LLC_MAX_SEQUENCE) % 
 *                  llcl_window 
 *
 * i.e. we first calculate the number of frames we need to ``go back''
 * from the current one (really the next one, but that doesn't matter as
 * llcl_projvs is likewise of by plus one) and subtract that from the
 * pointer to the most recently taken frame (llcl_freeslot - 1).
 */

short
llc_seq2slot(struct llc_linkcb *linkp, short seqn)
{
	register sn = 0;

	sn = (linkp->llcl_freeslot + linkp->llcl_window - 
	      (linkp->llcl_projvs + LLC_MAX_SEQUENCE - seqn) % 
	      LLC_MAX_SEQUENCE) % linkp->llcl_window;

	return sn;
}

/*
 * LLC2 link state handler
 *
 * There is in most cases one function per LLC2 state. The LLC2 standard
 * ISO 8802-2 allows in some cases for ambiguities, i.e. we have the choice
 * to do one thing or the other. Right now I have just chosen one but have also 
 * indicated the spot by "multiple possibilities". One could make the behavior 
 * in those cases configurable, allowing the superuser to enter a profile word
 * (32/64 bits, whatever is needed) that would suit her needs [I quite like 
 * that idea, perhaps I'll get around to it].
 *
 * [Preceeding each state handler function is the description as taken from
 * ISO 8802-2, section 7.9.2.1]
 */

/*
 * ADM --- The connection component is in the asynchronous disconnected mode.
 *         It can accept an SABME PDU from a remote LLC SSAP or, at the request
 *         of the service access point user, can initiate an SABME PDU
 *         transmission to a remote LLC DSAP, to establish a data link
 *         connection. It also responds to a DISC command PDU and to any
 *         command PDU with the P bit set to ``1''.
 */
int
llc_state_ADM(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
	      int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case NL_CONNECT_REQUEST:
		llc_send(linkp, LLCFT_SABME, LLC_CMD, pollfinal);
		LLC_SETFLAG(linkp, P, pollfinal);
		LLC_SETFLAG(linkp, S, 0);
		linkp->llcl_retry = 0;
		LLC_NEWSTATE(linkp, SETUP);
		break;
	case LLCFT_SABME + LLC_CMD:
		/* 
		 * ISO 8802-2, table 7-1, ADM state says to set
		 * the P flag, yet this will cause an SABME [P] to be
		 * answered with an UA only, not an UA [F], all
		 * other `disconnected' states set the F flag, so ...
		 */
		LLC_SETFLAG(linkp, F, pollfinal);
		LLC_NEWSTATE(linkp, CONN);
		action = LLC_CONNECT_INDICATION;
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_DM, LLC_RSP, pollfinal);
		break;
	default:
		if (cmdrsp == LLC_CMD && pollfinal == 1) 
			llc_send(linkp, LLCFT_DM, LLC_RSP, 1);
		/* remain in ADM state */
	}

	return action;
}

/*
 * CONN --- The local connection component has received an SABME PDU from a
 *          remote LLC SSAP, and it is waiting for the local user to accept or
 *          refuse the connection.
 */
int
llc_state_CONN(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
	       int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case NL_CONNECT_RESPONSE:
		llc_send(linkp, LLCFT_UA, LLC_RSP, LLC_GETFLAG(linkp, F));
		LLC_RESETCOUNTER(linkp);
		LLC_SETFLAG(linkp, P, 0);
		LLC_SETFLAG(linkp, REMOTE_BUSY, 0);
		LLC_NEWSTATE(linkp, NORMAL);
		break;
	case NL_DISCONNECT_REQUEST:
		llc_send(linkp, LLCFT_DM, LLC_RSP, LLC_GETFLAG(linkp, F));
		LLC_NEWSTATE(linkp, ADM);
		break;
	case LLCFT_SABME + LLC_CMD:
		LLC_SETFLAG(linkp, F, pollfinal);
		break;
	case LLCFT_DM + LLC_RSP:
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	/* all other frames effect nothing here */
	}

	return action;
}

/*
 * RESET_WAIT --- The local connection component is waiting for the local user
 *                 to indicate a RESET_REQUEST or a DISCONNECT_REQUEST.  
 */
int
llc_state_RESET_WAIT(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		     int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case NL_RESET_REQUEST:
		if (LLC_GETFLAG(linkp, S) == 0) {
			llc_send(linkp, LLCFT_SABME, LLC_CMD, pollfinal);
			LLC_SETFLAG(linkp, P, pollfinal);
			LLC_START_ACK_TIMER(linkp);
			linkp->llcl_retry = 0;
			LLC_NEWSTATE(linkp, RESET);
		} else {
			llc_send(linkp, LLCFT_UA, LLC_RSP, 
				      LLC_GETFLAG(linkp, F));
			LLC_RESETCOUNTER(linkp);
			LLC_SETFLAG(linkp, P, 0);
			LLC_SETFLAG(linkp, REMOTE_BUSY, 0);
			LLC_NEWSTATE(linkp, NORMAL);
			action = LLC_RESET_CONFIRM;
		}