object_identifier.c

RSA加密/解密算法源码 asn1c-0.9.12

		errno = EINVAL;
		return -1;
	}

	for(i = 0; i < oid->size; i++) {
		uint8_t b = oid->buf[i];
		if((b & 0x80))			/* Continuation expected */
			continue;

		if(num_arcs == 0) {
			/*
			 * First two arcs are encoded through the backdoor.
			 */
			unsigned LE = 1;	/* Little endian */
			int first_arc;
			num_arcs++;
			if(!arc_slots) { num_arcs++; continue; }

			if(i) first_arc = 2;
			else if(b <= 39) first_arc = 0;
			else if(b < 79)	first_arc = 1;
			else first_arc = 2;

			add = -40 * first_arc;
			memset(arcs, 0, arc_type_size);
			*(unsigned char *)((char *)arcs
				+ ((*(char *)&LE)?0:(arc_type_size - 1)))
					= first_arc;
			arcs = ((char *)arcs) + arc_type_size;
		}

		/* Decode, if has space */
		if(arcs < arcs_end) {
			if(OBJECT_IDENTIFIER_get_single_arc(&oid->buf[startn],
				i - startn + 1, add,
					arcs, arc_type_size))
				return -1;
			startn = i + 1;
			arcs = ((char *)arcs) + arc_type_size;
			add = 0;
		}
		num_arcs++;
	}

	return num_arcs;
}


/*
 * Save the single value as an object identifier arc.
 */
int
OBJECT_IDENTIFIER_set_single_arc(uint8_t *arcbuf, void *arcval, unsigned int arcval_size, int prepared_order) {
	/*
	 * The following conditions must hold:
	 * assert(arcval);
	 * assert(arcval_size > 0);
	 * assert(arcbuf);
	 */
#ifdef	WORDS_BIGENDIAN
	const unsigned isLittleEndian = 0;
#else
	unsigned LE = 1;
	unsigned isLittleEndian = *(char *)&LE;
#endif
	uint8_t *tp, *tend;
	unsigned int cache;
	uint8_t *bp = arcbuf;
	int bits;
#ifdef	__GNUC__
	uint8_t buffer[arcval_size];
#else
	uint8_t *buffer = alloca(arcval_size);
	if(!buffer) { errno = ENOMEM; return -1; }
#endif

	if(isLittleEndian && !prepared_order) {
		uint8_t *a = (unsigned char *)arcval + arcval_size - 1;
		uint8_t *aend = (uint8_t *)arcval;
		uint8_t *msb = buffer + arcval_size - 1;
		for(tp = buffer; a >= aend; tp++, a--)
			if((*tp = *a) && (tp < msb))
				msb = tp;
		tend = &buffer[arcval_size];
		tp = msb;	/* Most significant non-zero byte */
	} else {
		/* Look for most significant non-zero byte */
		tend = (unsigned char *)arcval + arcval_size;
		for(tp = (uint8_t *)arcval; tp < tend - 1; tp++)
			if(*tp) break;
	}

	/*
	 * Split the value in 7-bits chunks.
	 */
	bits = ((tend - tp) * CHAR_BIT) % 7;
	if(bits) {
		cache = *tp >> (CHAR_BIT - bits);
		if(cache) {
			*bp++ = cache | 0x80;
			cache = *tp++;
			bits = CHAR_BIT - bits;
		} else {
			bits = -bits;
		}
	} else {
		cache = 0;
	}
	for(; tp < tend; tp++) {
		cache = (cache << CHAR_BIT) + *tp;
		bits += CHAR_BIT;
		while(bits >= 7) {
			bits -= 7;
			*bp++ = 0x80 | (cache >> bits);
		}
	}
	if(bits) *bp++ = cache;
	bp[-1] &= 0x7f;	/* Clear the last bit */

	return bp - arcbuf;
}

int
OBJECT_IDENTIFIER_set_arcs(OBJECT_IDENTIFIER_t *oid, void *arcs, unsigned int arc_type_size, unsigned int arc_slots) {
	uint8_t *buf;
	uint8_t *bp;
	unsigned LE = 1;	/* Little endian (x86) */
	unsigned isLittleEndian = *((char *)&LE);
	unsigned int arc0;
	unsigned int arc1;
	unsigned size;
	unsigned i;

	if(!oid || !arcs || arc_type_size < 1 || arc_slots < 2) {
		errno = EINVAL;
		return -1;
	}

	switch(arc_type_size) {
	case sizeof(char):
		arc0 = ((unsigned char *)arcs)[0];
		arc1 = ((unsigned char *)arcs)[1];
		break;
	case sizeof(short):
		arc0 = ((unsigned short *)arcs)[0];
		arc1 = ((unsigned short *)arcs)[1];
		break;
	case sizeof(int):
		arc0 = ((unsigned int *)arcs)[0];
		arc1 = ((unsigned int *)arcs)[1];
		break;
	default:
		arc1 = arc0 = 0;
		if(isLittleEndian) {	/* Little endian (x86) */
			unsigned char *ps, *pe;
			/* If more significant bytes are present,
			 * make them > 255 quick */
			for(ps = (unsigned char *)arcs + 1, pe = ps+arc_type_size;
					ps < pe; ps++)
				arc0 |= *ps, arc1 |= *(ps + arc_type_size);
			arc0 <<= CHAR_BIT, arc1 <<= CHAR_BIT;
			arc0 = *((unsigned char *)arcs + 0);
			arc1 = *((unsigned char *)arcs + arc_type_size);
		} else {
			unsigned char *ps, *pe;
			/* If more significant bytes are present,
			 * make them > 255 quick */
			for(ps = (unsigned char *)arcs, pe = ps+arc_type_size - 1; ps < pe; ps++)
				arc0 |= *ps, arc1 |= *(ps + arc_type_size);
			arc0 = *((unsigned char *)arcs + arc_type_size - 1);
			arc1 = *((unsigned char *)arcs +(arc_type_size<< 1)-1);
		}
	}

	/*
	 * The previous chapter left us with the first and the second arcs.
	 * The values are not precise (that is, they are valid only if
	 * they're less than 255), but OK for the purposes of making
	 * the sanity test below.
	 */
	if(arc0 <= 1) {
		if(arc1 >= 39) {
			/* 8.19.4: At most 39 subsequent values (including 0) */
			errno = ERANGE;
			return -1;
		}
	} else if(arc0 > 2) {
		/* 8.19.4: Only three values are allocated from the root node */
		errno = ERANGE;
		return -1;
	}
	/*
	 * After above tests it is known that the value of arc0 is completely
	 * trustworthy (0..2). However, the arc1's value is still meaningless.
	 */

	/*
	 * Roughly estimate the maximum size necessary to encode these arcs.
	 * This estimation implicitly takes in account the following facts,
	 * that cancel each other:
	 * 	* the first two arcs are encoded in a single value.
	 * 	* the first value may require more space (+1 byte)
	 * 	* the value of the first arc which is in range (0..2)
	 */
	size = ((arc_type_size * CHAR_BIT + 6) / 7) * arc_slots;
	bp = buf = (uint8_t *)MALLOC(size + 1);
	if(!buf) {
		/* ENOMEM */
		return -1;
	}

	/*
	 * Encode the first two arcs.
	 * These require special treatment.
	 */
	{
		uint8_t *tp;
#ifdef	__GNUC__
		uint8_t first_value[1 + arc_type_size];	/* of two arcs */
		uint8_t *fv = first_value;
#else
		uint8_t *first_value = alloca(1 + arc_type_size);
		uint8_t *fv = first_value;
		if(!first_value) {
			errno = ENOMEM;
			return -1;
		}
#endif

		/*
		 * Simulate first_value = arc0 * 40 + arc1;
		 */
		/* Copy the second (1'st) arcs[1] into the first_value */
		*fv++ = 0;
		arcs = ((char *)arcs) + arc_type_size;
		if(isLittleEndian) {
			uint8_t *aend = (unsigned char *)arcs - 1;
			uint8_t *a1 = (unsigned char *)arcs + arc_type_size - 1;
			for(; a1 > aend; fv++, a1--) *fv = *a1;
		} else {
			uint8_t *a1 = (uint8_t *)arcs;
			uint8_t *aend = a1 + arc_type_size;
			for(; a1 < aend; fv++, a1++) *fv = *a1;
		}
		/* Increase the first_value by arc0 */
		arc0 *= 40;	/* (0..80) */
		for(tp = first_value + arc_type_size; tp >= first_value; tp--) {
			unsigned int v = *tp;
			v += arc0;
			*tp = v;
			if(v >= (1 << CHAR_BIT)) arc0 = v >> CHAR_BIT;
			else break;
		}

		assert(tp >= first_value);

		bp += OBJECT_IDENTIFIER_set_single_arc(bp, first_value,
			fv - first_value, 1);
 	}

	/*
	 * Save the rest of arcs.
	 */
	for(arcs = ((char *)arcs) + arc_type_size, i = 2;
		i < arc_slots;
			i++, arcs = ((char *)arcs) + arc_type_size) {
		bp += OBJECT_IDENTIFIER_set_single_arc(bp,
			arcs, arc_type_size, 0);
	}

	assert((unsigned)(bp - buf) <= size);

	/*
	 * Replace buffer.
	 */
	oid->size = bp - buf;
	bp = oid->buf;
	oid->buf = buf;
	if(bp) FREEMEM(bp);

	return 0;
}


int
OBJECT_IDENTIFIER_parse_arcs(const char *oid_text, ssize_t oid_txt_length,
	long *arcs, unsigned int arcs_slots, const char **oid_text_end) {
	unsigned int arcs_count = 0;
	const char *oid_end;
	long value = 0;
	enum {
		ST_SKIPSPACE,
		ST_WAITDIGITS,	/* Next character is expected to be a digit */
		ST_DIGITS,
	} state = ST_SKIPSPACE;

	if(!oid_text || oid_txt_length < -1 || (arcs_slots && !arcs)) {
		if(oid_text_end) *oid_text_end = oid_text;
		errno = EINVAL;
		return -1;
	}

	if(oid_txt_length == -1)
		oid_txt_length = strlen(oid_text);

	for(oid_end = oid_text + oid_txt_length; oid_text<oid_end; oid_text++) {
	    switch(*oid_text) {
	    case 0x09: case 0x0a: case 0x0d: case 0x20:	/* whitespace */
		if(state == ST_SKIPSPACE) {
			continue;
		} else {
			break;	/* Finish */
		}
	    case 0x2e:	/* '.' */
		if(state != ST_DIGITS
		|| (oid_text + 1) == oid_end) {
			state = ST_WAITDIGITS;
			break;
		}
		if(arcs_count < arcs_slots)
			arcs[arcs_count] = value;
		arcs_count++;
		state = ST_WAITDIGITS;
		continue;
	    case 0x30: case 0x31: case 0x32: case 0x33: case 0x34:
	    case 0x35: case 0x36: case 0x37: case 0x38: case 0x39:
		if(state != ST_DIGITS) {
			state = ST_DIGITS;
			value = 0;
		}
		if(1) {
			long new_value = value * 10;
			if(new_value / 10 != value
			|| (value = new_value + (*oid_text - 0x30)) < 0) {
				/* Overflow */
				state = ST_WAITDIGITS;
				break;
			}
			continue;
		}
	    default:
		/* Unexpected symbols */
		state = ST_WAITDIGITS;
		break;
	    } /* switch() */
	    break;
	} /* for() */


	if(oid_text_end) *oid_text_end = oid_text;

	/* Finalize last arc */
	switch(state) {
	case ST_WAITDIGITS:
		errno = EINVAL;
		return -1;
	case ST_DIGITS:
		if(arcs_count < arcs_slots)
			arcs[arcs_count] = value;
		arcs_count++;
		/* Fall through */
	default:
		return arcs_count;
	}
}