clnp_options.c

早期freebsd实现

 *					the offset from the beginning of the mbuf data, not the
 *					actual address.
 */
clnp_opt_sanity(m, opts, len, oidx)
struct mbuf 		*m;		/* mbuf options reside in */
caddr_t				opts;	/* ptr to buffer containing options */
int					len;	/* length of buffer */
struct clnp_optidx	*oidx;	/* RETURN: filled in with option idx info */
{
	u_char	opcode;			/* code of particular option */
	u_char	oplen;			/* length of a particular option */
	caddr_t	opts_end;		/* ptr to end of options */
	u_char	pad = 0, secure = 0, srcrt = 0, recrt = 0, qos = 0, prior = 0;
							/* flags for catching duplicate options */
	
	IFDEBUG(D_OPTIONS)
		printf("clnp_opt_sanity: checking %d bytes of data:\n", len);
		dump_buf(opts, len);
	ENDDEBUG

	/* clear option index field if passed */
	bzero((caddr_t)oidx, sizeof(struct clnp_optidx));

	/*
	 *	We need to indicate whether the ER option is present. This is done
	 *	by overloading the er_reason field to also indicate presense of
	 *	the option along with the option value. I would like ER_INVALREAS
	 *	to have value 0, but alas, 0 is a valid er reason...
	 */
	oidx->cni_er_reason = ER_INVALREAS;

	opts_end = opts + len;
	while (opts < opts_end) {
		/* must have at least 2 bytes per option (opcode and len) */
		if (opts + 2 > opts_end)
			return(GEN_INCOMPLETE);
		
		opcode = *opts++;
		oplen = *opts++;
		IFDEBUG(D_OPTIONS)
			printf("clnp_opt_sanity: opcode is %x and oplen %d\n",
				opcode, oplen);
			printf("clnp_opt_sanity: clnpoval_SRCRT is %x\n", CLNPOVAL_SRCRT);

				switch (opcode) {
					case CLNPOVAL_PAD: {
						printf("CLNPOVAL_PAD\n");
					} break;
					case CLNPOVAL_SECURE: {
						printf("CLNPOVAL_SECURE\n");
					} break;
					case CLNPOVAL_SRCRT: {
							printf("CLNPOVAL_SRCRT\n");
					} break;
					case CLNPOVAL_RECRT: {
						printf("CLNPOVAL_RECRT\n");
					} break;
					case CLNPOVAL_QOS: {
						printf("CLNPOVAL_QOS\n");
					} break;
					case CLNPOVAL_PRIOR: {
						printf("CLNPOVAL_PRIOR\n");
					} break;
					case CLNPOVAL_ERREAS: {
						printf("CLNPOVAL_ERREAS\n");
					} break;
					default:
						printf("UKNOWN option %x\n", opcode);
				}
		ENDDEBUG

		/* don't allow crazy length values */
		if (opts + oplen > opts_end)
			return(GEN_INCOMPLETE);

		switch (opcode) {
			case CLNPOVAL_PAD:
				/*
				 *	Padding: increment pointer by length of padding
				 */
				if (pad++)						/* duplicate ? */
					return(GEN_DUPOPT);
				opts += oplen;
				break;

			case CLNPOVAL_SECURE: {
				u_char	format = *opts;

				if (secure++)					/* duplicate ? */
					return(GEN_DUPOPT);
				/*
				 *	Security: high 2 bits of first octet indicate format
				 *	(00 in high bits is reserved).
				 *	Remaining bits must be 0. Remaining octets indicate
				 *	actual security
				 */
				if (((format & 0x3f) > 0) ||	/* low 6 bits set ? */
					((format & 0xc0) == 0))		/* high 2 bits zero ? */
					return(GEN_HDRSYNTAX);

				oidx->cni_securep = CLNP_OPTTOOFF(m, opts);
				oidx->cni_secure_len = oplen;
				opts += oplen;
			} break;

			case CLNPOVAL_SRCRT: {
				u_char	type, offset;	/* type of rt, offset of start */
				caddr_t	route_end;		/* address of end of route option */

				IFDEBUG(D_OPTIONS)
					printf("clnp_opt_sanity: SRC RT\n");
				ENDDEBUG

				if (srcrt++)					/* duplicate ? */
					return(GEN_DUPOPT);
				/* 
				 *	source route: There must be 2 bytes following the length
				 *	field: type and offset. The type must be either
				 *	partial route or complete route. The offset field must
				 *	be within the option. A single exception is made, however.
				 *	The offset may be 1 greater than the length. This case 
				 *	occurs when the last source route record is consumed. 
				 *	In this case, we ignore the source route option.
				 *	RAH? You should be able to set offset to 'ff' like in record
				 *	route!
				 *	Following this is a series of address fields. 
				 *	Each address field is composed of a (length, address) pair.
				 *	Insure that the offset and each address length is reasonable
				 */
				route_end = opts + oplen;

				if (opts + 2 > route_end)
					return(SRCRT_SYNTAX);

				type = *opts;
				offset = *(opts+1);


				/* type must be partial or complete */
				if (!((type == CLNPOVAL_PARTRT) || (type == CLNPOVAL_COMPRT)))
					return(SRCRT_SYNTAX);
				
				oidx->cni_srcrt_s = CLNP_OPTTOOFF(m, opts);
				oidx->cni_srcrt_len = oplen;

				opts += offset-1;	/*set opts to first addr in rt */

				/* 
				 *	Offset must be reasonable:
				 *	less than end of options, or equal to end of options
				 */
				if (opts >= route_end) {
					if (opts == route_end) {
						IFDEBUG(D_OPTIONS)
							printf("clnp_opt_sanity: end of src route info\n");
						ENDDEBUG
						break;
					} else 
						return(SRCRT_SYNTAX);
				}

				while (opts < route_end) {
					u_char	addrlen = *opts++;
					if (opts + addrlen > route_end)
						return(SRCRT_SYNTAX);
					opts += addrlen;
				}
			} break;
			case CLNPOVAL_RECRT: {
				u_char	type, offset;	/* type of rt, offset of start */
				caddr_t	record_end;		/* address of end of record option */

				if (recrt++)					/* duplicate ? */
					return(GEN_DUPOPT);
				/*
				 *	record route: after the length field, expect a
				 *	type and offset. Type must be partial or complete.
				 *	Offset indicates where to start recording. Insure it
				 *	is within the option. All ones for offset means
				 *	recording is terminated.
				 */
				record_end = opts + oplen;

				oidx->cni_recrtp = CLNP_OPTTOOFF(m, opts);
				oidx->cni_recrt_len = oplen;

				if (opts + 2 > record_end)
					return(GEN_INCOMPLETE);

				type = *opts;
				offset = *(opts+1);

				/* type must be partial or complete */
				if (!((type == CLNPOVAL_PARTRT) || (type == CLNPOVAL_COMPRT)))
					return(GEN_HDRSYNTAX);
				
				/* offset must be reasonable */
				if ((offset < 0xff) && (opts + offset > record_end))
					return(GEN_HDRSYNTAX);
				opts += oplen;
			} break;
			case CLNPOVAL_QOS: {
				u_char	format = *opts;

				if (qos++)					/* duplicate ? */
					return(GEN_DUPOPT);
				/*
				 *	qos: high 2 bits of first octet indicate format
				 *	(00 in high bits is reserved).
				 *	Remaining bits must be 0 (unless format indicates
				 *	globally unique qos, in which case remaining bits indicate
				 *	qos (except bit 6 which is reserved)).  Otherwise,
				 *	remaining octets indicate actual qos.
				 */
				if (((format & 0xc0) == 0) ||	/* high 2 bits zero ? */
					(((format & 0xc0) != CLNPOVAL_GLOBAL) && 
						((format & 0x3f) > 0))) /* not global,low bits used ? */
					return(GEN_HDRSYNTAX);
				
				oidx->cni_qos_formatp = CLNP_OPTTOOFF(m, opts);
				oidx->cni_qos_len = oplen;

				opts += oplen;
			} break;

			case CLNPOVAL_PRIOR: {
				if (prior++)				/* duplicate ? */
					return(GEN_DUPOPT);
				/*
				 *	priority: value must be one byte long
				 */
				if (oplen != 1)
					return(GEN_HDRSYNTAX);
				
				oidx->cni_priorp = CLNP_OPTTOOFF(m, opts);

				opts += oplen;
			} break;

			case CLNPOVAL_ERREAS: {
				/*
				 *	er reason: value must be two bytes long
				 */
				if (oplen != 2)
					return(GEN_HDRSYNTAX);

				oidx->cni_er_reason = *opts;

				opts += oplen;
			} break;

			default: {
				IFDEBUG(D_OPTIONS)
					printf("clnp_opt_sanity: UNKNOWN OPTION 0x%x\n", opcode);
				ENDDEBUG
				return(DISC_UNSUPPOPT);
			}
		}
	}
		IFDEBUG(D_OPTIONS)
			printf("clnp_opt_sanity: return(0)\n", opcode);
		ENDDEBUG
	return(0);
}
#endif	/* ISO */