/*-
 * Copyright (c) 2003-2014 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#include <asn_internal.h>
#include <INTEGER.h>
#include <asn_codecs_prim.h>	/* Encoder and decoder of a primitive type */
#include <errno.h>

/*
 * INTEGER basic type description.
 */
static ber_tlv_tag_t asn_DEF_INTEGER_tags[] = {
	(ASN_TAG_CLASS_UNIVERSAL | (2 << 2))
};
asn_TYPE_descriptor_t asn_DEF_INTEGER = {
	"INTEGER",
	"INTEGER",
	ASN__PRIMITIVE_TYPE_free,
	0,
	asn_generic_no_constraint,
	ber_decode_primitive,
	INTEGER_encode_der,
	0,
	0,
	0,
	0,
	0, /* Use generic outmost tag fetcher */
	asn_DEF_INTEGER_tags,
	sizeof(asn_DEF_INTEGER_tags) / sizeof(asn_DEF_INTEGER_tags[0]),
	asn_DEF_INTEGER_tags,	/* Same as above */
	sizeof(asn_DEF_INTEGER_tags) / sizeof(asn_DEF_INTEGER_tags[0]),
	0,	/* No PER visible constraints */
	0, 0,	/* No members */
	0	/* No specifics */
};

/*
 * Encode INTEGER type using DER.
 */
asn_enc_rval_t
INTEGER_encode_der(asn_TYPE_descriptor_t *td, void *sptr,
	int tag_mode, ber_tlv_tag_t tag,
	asn_app_consume_bytes_f *cb, void *app_key) {
	INTEGER_t *st = (INTEGER_t *)sptr;

	ASN_DEBUG("%s %s as INTEGER (tm=%d)",
		cb?"Encoding":"Estimating", td->name, tag_mode);

	/*
	 * Canonicalize integer in the buffer.
	 * (Remove too long sign extension, remove some first 0x00 bytes)
	 */
	if(st->buf) {
		uint8_t *buf = st->buf;
		uint8_t *end1 = buf + st->size - 1;
		int shift;

		/* Compute the number of superfluous leading bytes */
		for(; buf < end1; buf++) {
			/*
			 * If the contents octets of an integer value encoding
			 * consist of more than one octet, then the bits of the
			 * first octet and bit 8 of the second octet:
			 * a) shall not all be ones; and
			 * b) shall not all be zero.
			 */
			switch(*buf) {
			case 0x00: if((buf[1] & 0x80) == 0)
					continue;
				break;
			case 0xff: if((buf[1] & 0x80))
					continue;
				break;
			}
			break;
		}

		/* Remove leading superfluous bytes from the integer */
		shift = buf - st->buf;
		if(shift) {
			uint8_t *nb = st->buf;
			uint8_t *end;

			st->size -= shift;	/* New size, minus bad bytes */
			end = nb + st->size;

			for(; nb < end; nb++, buf++)
				*nb = *buf;
		}

	} /* if(1) */

	return der_encode_primitive(td, sptr, tag_mode, tag, cb, app_key);
}

static int
INTEGER__compar_value2enum(const void *kp, const void *am) {
	long a = *(const long *)kp;
	const asn_INTEGER_enum_map_t *el = (const asn_INTEGER_enum_map_t *)am;
	long b = el->nat_value;
	if(a < b) return -1;
	else if(a == b) return 0;
	else return 1;
}

const asn_INTEGER_enum_map_t *
INTEGER_map_value2enum(asn_INTEGER_specifics_t *specs, long value) {
	int count = specs ? specs->map_count : 0;
	if(!count) return 0;
	return (asn_INTEGER_enum_map_t *)bsearch(&value, specs->value2enum,
		count, sizeof(specs->value2enum[0]),
		INTEGER__compar_value2enum);
}

int
asn_INTEGER2long(const INTEGER_t *iptr, long *lptr) {
	uint8_t *b, *end;
	size_t size;
	long l;

	/* Sanity checking */
	if(!iptr || !iptr->buf || iptr->size < 0 || !lptr) {
		errno = EINVAL;
		return -1;
	}

	/* Cache the begin/end of the buffer */
	b = iptr->buf;	/* Start of the INTEGER buffer */
	size = (size_t)iptr->size;
	end = b + size;	/* Where to stop */

	if(size > sizeof(long)) {
		uint8_t *end1 = end - 1;
		/*
		 * Slightly more advanced processing,
		 * able to >sizeof(long) bytes,
		 * when the actual value is small
		 * (0x0000000000abcdef would yield a fine 0x00abcdef)
		 */
		/* Skip out the insignificant leading bytes */
		for(; b < end1; b++) {
			switch(*b) {
			case 0x00: if((b[1] & 0x80) == 0) continue; break;
			case 0xff: if((b[1] & 0x80) != 0) continue; break;
			}
			break;
		}

		size = end - b;
		if(size > sizeof(long)) {
			/* Still cannot fit the long */
			errno = ERANGE;
			return -1;
		}
	}

	/* Shortcut processing of a corner case */
	if(end == b) {
		*lptr = 0;
		return 0;
	}

	/* Perform the sign initialization */
	/* Actually l = -(*b >> 7); gains nothing, yet unreadable! */
	if((*b >> 7)) l = -1; else l = 0;

	/* Conversion engine */
	for(; b < end; b++)
		l = (l << 8) | *b;

	*lptr = l;
	return 0;
}

int
asn_INTEGER2ulong(const INTEGER_t *iptr, unsigned long *lptr) {
	uint8_t *b, *end;
	unsigned long l;
	size_t size;

	if(!iptr || !iptr->buf || iptr->size < 0 || !lptr) {
		errno = EINVAL;
		return -1;
	}

	b = iptr->buf;
	size = (size_t)iptr->size;
	end = b + size;

	/* If all extra leading bytes are zeroes, ignore them */
	for(; size > sizeof(unsigned long); b++, size--) {
		if(*b) {
			/* Value won't fit unsigned long */
			errno = ERANGE;
			return -1;
		}
	}

	/* Conversion engine */
	for(l = 0; b < end; b++)
		l = (l << 8) | *b;

	*lptr = l;
	return 0;
}

int
asn_ulong2INTEGER(INTEGER_t *st, unsigned long value) {
	uint8_t *buf;
	uint8_t *end;
	uint8_t *b;
	int shr;

	if(value <= LONG_MAX)
		return asn_long2INTEGER(st, value);

	buf = (uint8_t *)MALLOC(1 + sizeof(value));
	if(!buf) return -1;

	end = buf + (sizeof(value) + 1);
	buf[0] = 0;
	for(b = buf + 1, shr = (sizeof(long)-1)*8; b < end; shr -= 8, b++)
		*b = (uint8_t)(value >> shr);

	if(st->buf) FREEMEM(st->buf);
	st->buf = buf;
	st->size = 1 + sizeof(value);

	return 0;
}

int
asn_long2INTEGER(INTEGER_t *st, long value) {
	uint8_t *buf, *bp;
	uint8_t *p;
	uint8_t *pstart;
	uint8_t *pend1;
	int littleEndian = 1;	/* Run-time detection */
	int add;

	if(!st) {
		errno = EINVAL;
		return -1;
	}

	buf = (uint8_t *)MALLOC(sizeof(value));
	if(!buf) return -1;

	if(*(char *)&littleEndian) {
		pstart = (uint8_t *)&value + sizeof(value) - 1;
		pend1 = (uint8_t *)&value;
		add = -1;
	} else {
		pstart = (uint8_t *)&value;
		pend1 = pstart + sizeof(value) - 1;
		add = 1;
	}

	/*
	 * If the contents octet consists of more than one octet,
	 * then bits of the first octet and bit 8 of the second octet:
	 * a) shall not all be ones; and
	 * b) shall not all be zero.
	 */
	for(p = pstart; p != pend1; p += add) {
		switch(*p) {
		case 0x00: if((*(p+add) & 0x80) == 0)
				continue;
			break;
		case 0xff: if((*(p+add) & 0x80))
				continue;
			break;
		}
		break;
	}
	/* Copy the integer body */
	for(pstart = p, bp = buf, pend1 += add; p != pend1; p += add)
		*bp++ = *p;

	if(st->buf) FREEMEM(st->buf);
	st->buf = buf;
	st->size = bp - buf;

	return 0;
}

/*
 * This function is going to be DEPRECATED soon.
 */
enum asn_strtol_result_e
asn_strtol(const char *str, const char *end, long *lp) {
    const char *endp = end;

    switch(asn_strtol_lim(str, &endp, lp)) {
    case ASN_STRTOL_ERROR_RANGE:
        return ASN_STRTOL_ERROR_RANGE;
    case ASN_STRTOL_ERROR_INVAL:
        return ASN_STRTOL_ERROR_INVAL;
    case ASN_STRTOL_EXPECT_MORE:
        return ASN_STRTOL_ERROR_INVAL;  /* Retain old behavior */
    case ASN_STRTOL_OK:
        return ASN_STRTOL_OK;
    case ASN_STRTOL_EXTRA_DATA:
        return ASN_STRTOL_ERROR_INVAL;  /* Retain old behavior */
    }

    return ASN_STRTOL_ERROR_INVAL;  /* Retain old behavior */
}

/*
 * Parse the number in the given string until the given *end position,
 * returning the position after the last parsed character back using the
 * same (*end) pointer.
 * WARNING: This behavior is different from the standard strtol(3).
 */
enum asn_strtol_result_e
asn_strtol_lim(const char *str, const char **end, long *lp) {
	int sign = 1;
	long l;

	const long upper_boundary = LONG_MAX / 10;
	long last_digit_max = LONG_MAX % 10;

	if(str >= *end) return ASN_STRTOL_ERROR_INVAL;

	switch(*str) {
	case '-':
		last_digit_max++;
		sign = -1;
	case '+':
		str++;
		if(str >= *end) {
			*end = str;
			return ASN_STRTOL_EXPECT_MORE;
		}
	}

	for(l = 0; str < (*end); str++) {
		switch(*str) {
		case 0x30: case 0x31: case 0x32: case 0x33: case 0x34:
		case 0x35: case 0x36: case 0x37: case 0x38: case 0x39: {
			int d = *str - '0';
			if(l < upper_boundary) {
				l = l * 10 + d;
			} else if(l == upper_boundary) {
				if(d <= last_digit_max) {
					if(sign > 0) {
						l = l * 10 + d;
					} else {
						sign = 1;
						l = -l * 10 - d;
					}
				} else {
					*end = str;
					return ASN_STRTOL_ERROR_RANGE;
				}
			} else {
				*end = str;
				return ASN_STRTOL_ERROR_RANGE;
			}
		    }
		    continue;
		default:
		    *end = str;
		    *lp = sign * l;
		    return ASN_STRTOL_EXTRA_DATA;
		}
	}

	*end = str;
	*lp = sign * l;
	return ASN_STRTOL_OK;
}