xref: /freebsd/contrib/ldns/dname.c (revision 5afab0e5e56fe90a378fb57249600e7924e1cab2)

/*
 * dname.c
 *
 * dname specific rdata implementations
 * A dname is a rdf structure with type LDNS_RDF_TYPE_DNAME
 * It is not a /real/ type! All function must therefore check
 * for LDNS_RDF_TYPE_DNAME.
 *
 * a Net::DNS like library for C
 *
 * (c) NLnet Labs, 2004-2006
 *
 * See the file LICENSE for the license
 */

#include <ldns/config.h>

#include <ldns/ldns.h>

#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif

/* Returns whether the last label in the name is a root label (a empty label).
 * Note that it is not enough to just test the last character to be 0,
 * because it may be part of the last label itself.
 */
static bool
ldns_dname_last_label_is_root_label(const ldns_rdf* dname)
{
	size_t src_pos;
	size_t len = 0;

	for (src_pos = 0; src_pos < ldns_rdf_size(dname); src_pos += len + 1) {
		len = ldns_rdf_data(dname)[src_pos];
	}
	assert(src_pos == ldns_rdf_size(dname));

	return src_pos > 0 && len == 0;
}

ldns_rdf *
ldns_dname_cat_clone(const ldns_rdf *rd1, const ldns_rdf *rd2)
{
	ldns_rdf *new;
	uint16_t new_size;
	uint8_t *buf;
	uint16_t left_size;

	if (ldns_rdf_get_type(rd1) != LDNS_RDF_TYPE_DNAME ||
			ldns_rdf_get_type(rd2) != LDNS_RDF_TYPE_DNAME) {
		return NULL;
	}

	/* remove root label if it is present at the end of the left
	 * rd, by reducing the size with 1
	 */
	left_size = ldns_rdf_size(rd1);
	if (ldns_dname_last_label_is_root_label(rd1)) {
		left_size--;
	}

	/* we overwrite the nullbyte of rd1 */
	new_size = left_size + ldns_rdf_size(rd2);
	buf = LDNS_XMALLOC(uint8_t, new_size);
	if (!buf) {
		return NULL;
	}

	/* put the two dname's after each other */
	memcpy(buf, ldns_rdf_data(rd1), left_size);
	memcpy(buf + left_size, ldns_rdf_data(rd2), ldns_rdf_size(rd2));

	new = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME, new_size, buf);

	LDNS_FREE(buf);
	return new;
}

ldns_status
ldns_dname_cat(ldns_rdf *rd1, const ldns_rdf *rd2)
{
	uint16_t left_size;
	uint16_t size;
	uint8_t* newd;

	if (ldns_rdf_get_type(rd1) != LDNS_RDF_TYPE_DNAME ||
			ldns_rdf_get_type(rd2) != LDNS_RDF_TYPE_DNAME) {
		return LDNS_STATUS_ERR;
	}

	/* remove root label if it is present at the end of the left
	 * rd, by reducing the size with 1
	 */
	left_size = ldns_rdf_size(rd1);
	if (ldns_dname_last_label_is_root_label(rd1)) {
		left_size--;
	}

	size = left_size + ldns_rdf_size(rd2);
	newd = LDNS_XREALLOC(ldns_rdf_data(rd1), uint8_t, size);
	if(!newd) {
		return LDNS_STATUS_MEM_ERR;
	}

	ldns_rdf_set_data(rd1, newd);
	memcpy(ldns_rdf_data(rd1) + left_size, ldns_rdf_data(rd2),
			ldns_rdf_size(rd2));
	ldns_rdf_set_size(rd1, size);

	return LDNS_STATUS_OK;
}

ldns_rdf*
ldns_dname_reverse(const ldns_rdf *dname)
{
	size_t rd_size;
	uint8_t* buf;
	ldns_rdf* new;
	size_t src_pos;
	size_t len ;

	assert(ldns_rdf_get_type(dname) == LDNS_RDF_TYPE_DNAME);

	rd_size = ldns_rdf_size(dname);
	buf = LDNS_XMALLOC(uint8_t, rd_size);
	if (! buf) {
		return NULL;
	}
	new = ldns_rdf_new(LDNS_RDF_TYPE_DNAME, rd_size, buf);
	if (! new) {
		LDNS_FREE(buf);
		return NULL;
	}

	/* If dname ends in a root label, the reverse should too.
	 */
	if (ldns_dname_last_label_is_root_label(dname)) {
		buf[rd_size - 1] = 0;
		rd_size -= 1;
	}
	for (src_pos = 0; src_pos < rd_size; src_pos += len + 1) {
		len = ldns_rdf_data(dname)[src_pos];
		memcpy(&buf[rd_size - src_pos - len - 1],
				&ldns_rdf_data(dname)[src_pos], len + 1);
	}
	return new;
}

ldns_rdf *
ldns_dname_clone_from(const ldns_rdf *d, uint16_t n)
{
	uint8_t *data;
	uint8_t label_size;
	size_t data_size;

	if (!d ||
	    ldns_rdf_get_type(d) != LDNS_RDF_TYPE_DNAME ||
	    ldns_dname_label_count(d) < n) {
		return NULL;
	}

	data = ldns_rdf_data(d);
	data_size = ldns_rdf_size(d);
	while (n > 0) {
		label_size = data[0] + 1;
		data += label_size;
		if (data_size < label_size) {
			/* this label is very broken */
			return NULL;
		}
		data_size -= label_size;
		n--;
	}

	return ldns_dname_new_frm_data(data_size, data);
}

ldns_rdf *
ldns_dname_left_chop(const ldns_rdf *d)
{
	uint8_t label_pos;
	ldns_rdf *chop;

	if (!d) {
		return NULL;
	}

	if (ldns_rdf_get_type(d) != LDNS_RDF_TYPE_DNAME) {
		return NULL;
	}
	if (ldns_dname_label_count(d) == 0) {
		/* root label */
		return NULL;
	}
	/* 05blaat02nl00 */
	label_pos = ldns_rdf_data(d)[0];

	chop = ldns_dname_new_frm_data(ldns_rdf_size(d) - label_pos - 1,
			ldns_rdf_data(d) + label_pos + 1);
	return chop;
}

uint8_t
ldns_dname_label_count(const ldns_rdf *r)
{
        uint16_t src_pos;
        uint16_t len;
        uint8_t i;
        size_t r_size;

	if (!r) {
		return 0;
	}

	i = 0;
	src_pos = 0;
	r_size = ldns_rdf_size(r);

	if (ldns_rdf_get_type(r) != LDNS_RDF_TYPE_DNAME) {
		return 0;
	} else {
		len = ldns_rdf_data(r)[src_pos]; /* start of the label */

		/* single root label */
		if (1 == r_size) {
			return 0;
		} else {
			while ((len > 0) && src_pos < r_size) {
				src_pos++;
				src_pos += len;
				len = ldns_rdf_data(r)[src_pos];
				i++;
			}
		}
	}
	return i;
}

ldns_rdf *
ldns_dname_new(uint16_t s, void *d)
{
        ldns_rdf *rd;

        if (!s || !d) {
                return NULL;
        }
        rd = LDNS_MALLOC(ldns_rdf);
        if (!rd) {
                return NULL;
        }
        ldns_rdf_set_size(rd, s);
        ldns_rdf_set_type(rd, LDNS_RDF_TYPE_DNAME);
        ldns_rdf_set_data(rd, d);
        return rd;
}

ldns_rdf *
ldns_dname_new_frm_str(const char *str)
{
	return ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, str);
}

ldns_rdf *
ldns_dname_new_frm_data(uint16_t size, const void *data)
{
	return ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME, size, data);
}

void
ldns_dname2canonical(const ldns_rdf *rd)
{
	uint8_t *rdd;
	uint16_t i;

	if (ldns_rdf_get_type(rd) != LDNS_RDF_TYPE_DNAME) {
		return;
	}

	rdd = (uint8_t*)ldns_rdf_data(rd);
	for (i = 0; i < ldns_rdf_size(rd); i++, rdd++) {
		*rdd = (uint8_t)LDNS_DNAME_NORMALIZE((int)*rdd);
	}
}

bool
ldns_dname_is_subdomain(const ldns_rdf *sub, const ldns_rdf *parent)
{
	uint8_t sub_lab;
	uint8_t par_lab;
	int8_t i, j;
	ldns_rdf *tmp_sub = NULL;
	ldns_rdf *tmp_par = NULL;
    ldns_rdf *sub_clone;
    ldns_rdf *parent_clone;
    bool result = true;

	if (ldns_rdf_get_type(sub) != LDNS_RDF_TYPE_DNAME ||
			ldns_rdf_get_type(parent) != LDNS_RDF_TYPE_DNAME ||
			ldns_rdf_compare(sub, parent) == 0) {
		return false;
	}

    /* would be nicer if we do not have to clone... */
    sub_clone = ldns_dname_clone_from(sub, 0);
    parent_clone = ldns_dname_clone_from(parent, 0);
    ldns_dname2canonical(sub_clone);
    ldns_dname2canonical(parent_clone);

	sub_lab = ldns_dname_label_count(sub_clone);
	par_lab = ldns_dname_label_count(parent_clone);

	/* if sub sits above parent, it cannot be a child/sub domain */
	if (sub_lab < par_lab) {
		result = false;
	} else {
		/* check all labels the from the parent labels, from right to left.
		 * When they /all/ match we have found a subdomain
		 */
		j = sub_lab - 1; /* we count from zero, thank you */
		for (i = par_lab -1; i >= 0; i--) {
			tmp_sub = ldns_dname_label(sub_clone, j);
			tmp_par = ldns_dname_label(parent_clone, i);
			if (!tmp_sub || !tmp_par) {
				/* deep free does null check */
				ldns_rdf_deep_free(tmp_sub);
				ldns_rdf_deep_free(tmp_par);
				result = false;
				break;
			}

			if (ldns_rdf_compare(tmp_sub, tmp_par) != 0) {
				/* they are not equal */
				ldns_rdf_deep_free(tmp_sub);
				ldns_rdf_deep_free(tmp_par);
				result = false;
				break;
			}
			ldns_rdf_deep_free(tmp_sub);
			ldns_rdf_deep_free(tmp_par);
			j--;
		}
	}
	ldns_rdf_deep_free(sub_clone);
	ldns_rdf_deep_free(parent_clone);
	return result;
}

int
ldns_dname_compare(const ldns_rdf *dname1, const ldns_rdf *dname2)
{
	size_t lc1, lc2, lc1f, lc2f;
	size_t i;
	int result = 0;
	uint8_t *lp1, *lp2;

	/* see RFC4034 for this algorithm */
	/* this algorithm assumes the names are normalized to case */

        /* only when both are not NULL we can say anything about them */
        if (!dname1 && !dname2) {
                return 0;
        }
        if (!dname1 || !dname2) {
                return -1;
        }
	/* asserts must happen later as we are looking in the
	 * dname, which could be NULL. But this case is handled
	 * above
	 */
	assert(ldns_rdf_get_type(dname1) == LDNS_RDF_TYPE_DNAME);
	assert(ldns_rdf_get_type(dname2) == LDNS_RDF_TYPE_DNAME);

	lc1 = ldns_dname_label_count(dname1);
	lc2 = ldns_dname_label_count(dname2);

	if (lc1 == 0 && lc2 == 0) {
		return 0;
	}
	if (lc1 == 0) {
		return -1;
	}
	if (lc2 == 0) {
		return 1;
	}
	lc1--;
	lc2--;
	/* we start at the last label */
	while (true) {
		/* find the label first */
		lc1f = lc1;
		lp1 = ldns_rdf_data(dname1);
		while (lc1f > 0) {
			lp1 += *lp1 + 1;
			lc1f--;
		}

		/* and find the other one */
		lc2f = lc2;
		lp2 = ldns_rdf_data(dname2);
		while (lc2f > 0) {
			lp2 += *lp2 + 1;
			lc2f--;
		}

		/* now check the label character for character. */
		for (i = 1; i < (size_t)(*lp1 + 1); i++) {
			if (i > *lp2) {
				/* apparently label 1 is larger */
				result = 1;
				goto done;
			}
			if (LDNS_DNAME_NORMALIZE((int) *(lp1 + i)) <
			    LDNS_DNAME_NORMALIZE((int) *(lp2 + i))) {
			    result = -1;
			    goto done;
			} else if (LDNS_DNAME_NORMALIZE((int) *(lp1 + i)) >
			    LDNS_DNAME_NORMALIZE((int) *(lp2 + i))) {
			    result = 1;
			    goto done;
			}
		}
		if (*lp1 < *lp2) {
			/* apparently label 2 is larger */
			result = -1;
			goto done;
		}
		if (lc1 == 0 && lc2 > 0) {
			result = -1;
			goto done;
		} else if (lc1 > 0 && lc2 == 0) {
			result = 1;
			goto done;
		} else if (lc1 == 0 && lc2 == 0) {
			result = 0;
			goto done;
		}
		lc1--;
		lc2--;
	}

	done:
	return result;
}

int
ldns_dname_is_wildcard(const ldns_rdf* dname)
{
	return ( ldns_dname_label_count(dname) > 0 &&
		 ldns_rdf_data(dname)[0] == 1 &&
		 ldns_rdf_data(dname)[1] == '*');
}

int
ldns_dname_match_wildcard(const ldns_rdf *dname, const ldns_rdf *wildcard)
{
	ldns_rdf *wc_chopped;
	int result;
	/* check whether it really is a wildcard */
	if (ldns_dname_is_wildcard(wildcard)) {
		/* ok, so the dname needs to be a subdomain of the wildcard
		 * without the *
		 */
		wc_chopped = ldns_dname_left_chop(wildcard);
		result = (int) ldns_dname_is_subdomain(dname, wc_chopped);
		ldns_rdf_deep_free(wc_chopped);
	} else {
		result = (ldns_dname_compare(dname, wildcard) == 0);
	}
	return result;
}

/* nsec test: does prev <= middle < next
 * -1 = yes
 * 0 = error/can't tell
 * 1 = no
 */
int
ldns_dname_interval(const ldns_rdf *prev, const ldns_rdf *middle,
		const ldns_rdf *next)
{
	int prev_check, next_check;

	assert(ldns_rdf_get_type(prev) == LDNS_RDF_TYPE_DNAME);
	assert(ldns_rdf_get_type(middle) == LDNS_RDF_TYPE_DNAME);
	assert(ldns_rdf_get_type(next) == LDNS_RDF_TYPE_DNAME);

	prev_check = ldns_dname_compare(prev, middle);
	next_check = ldns_dname_compare(middle, next);
	/* <= next. This cannot be the case for nsec, because then we would
	 * have gotten the nsec of next...
	 */
	if (next_check == 0) {
		return 0;
	}

			/* <= */
	if ((prev_check == -1 || prev_check == 0) &&
			/* < */
			next_check == -1) {
		return -1;
	} else {
		return 1;
	}
}


bool
ldns_dname_str_absolute(const char *dname_str)
{
        const char* s;
	if(dname_str && strcmp(dname_str, ".") == 0)
		return 1;
        if(!dname_str || strlen(dname_str) < 2)
                return 0;
        if(dname_str[strlen(dname_str) - 1] != '.')
                return 0;
        if(dname_str[strlen(dname_str) - 2] != '\\')
                return 1; /* ends in . and no \ before it */
        /* so we have the case of ends in . and there is \ before it */
        for(s=dname_str; *s; s++) {
                if(*s == '\\') {
                        if(s[1] && s[2] && s[3] /* check length */
                                && isdigit((unsigned char)s[1])
				&& isdigit((unsigned char)s[2])
				&& isdigit((unsigned char)s[3]))
                                s += 3;
                        else if(!s[1] || isdigit((unsigned char)s[1])) /* escape of nul,0-9 */
                                return 0; /* parse error */
                        else s++; /* another character escaped */
                }
                else if(!*(s+1) && *s == '.')
                        return 1; /* trailing dot, unescaped */
        }
        return 0;
}

bool
ldns_dname_absolute(const ldns_rdf *rdf)
{
	char *str = ldns_rdf2str(rdf);
	if (str) {
		bool r = ldns_dname_str_absolute(str);
		LDNS_FREE(str);
		return r;
	}
	return false;
}

ldns_rdf *
ldns_dname_label(const ldns_rdf *rdf, uint8_t labelpos)
{
	uint8_t labelcnt;
	uint16_t src_pos;
	uint16_t len;
	ldns_rdf *tmpnew;
	size_t s;
	uint8_t *data;

	if (ldns_rdf_get_type(rdf) != LDNS_RDF_TYPE_DNAME) {
		return NULL;
	}

	labelcnt = 0;
	src_pos = 0;
	s = ldns_rdf_size(rdf);

	len = ldns_rdf_data(rdf)[src_pos]; /* label start */
	while ((len > 0) && src_pos < s) {
		if (labelcnt == labelpos) {
			/* found our label */
			data = LDNS_XMALLOC(uint8_t, len + 2);
			if (!data) {
				return NULL;
			}
			memcpy(data, ldns_rdf_data(rdf) + src_pos, len + 1);
			data[len + 2 - 1] = 0;

			tmpnew = ldns_rdf_new( LDNS_RDF_TYPE_DNAME
					     , len + 2, data);
			if (!tmpnew) {
				LDNS_FREE(data);
				return NULL;
			}
			return tmpnew;
		}
		src_pos++;
		src_pos += len;
		len = ldns_rdf_data(rdf)[src_pos];
		labelcnt++;
	}
	return NULL;
}