wire2host.c

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/*
 * wire2host.c
 *
 * conversion routines from the wire to the host
 * format.
 * This will usually just a re-ordering of the
 * data (as we store it in network format)
 *
 * 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>
/*#include <ldns/wire2host.h>*/
 
#include <strings.h>
#include <limits.h>
 
 
 
/*
 * Set of macro's to deal with the dns message header as specified
 * in RFC1035 in portable way.
 *
 */
 
/*
 *
 *                                    1  1  1  1  1  1
 *      0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                      ID                       |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |QR|   Opcode  |AA|TC|RD|RA| Z|AD|CD|   RCODE   |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                    QDCOUNT                    |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                    ANCOUNT                    |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                    NSCOUNT                    |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                    ARCOUNT                    |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *
 */
 
 
/* allocates memory to *dname! */
ldns_status
ldns_wire2dname(ldns_rdf **dname, const uint8_t *wire, size_t max, size_t *pos)
{
        uint8_t label_size;
        uint16_t pointer_target;
        uint8_t pointer_target_buf[2];
        size_t dname_pos = 0;
        size_t uncompressed_length = 0;
        size_t compression_pos = 0;
        uint8_t tmp_dname[LDNS_MAX_DOMAINLEN];
        unsigned int pointer_count = 0;
 
        if (pos == NULL) {
                return LDNS_STATUS_WIRE_RDATA_ERR;
        }
        if (*pos >= max) {
                return LDNS_STATUS_PACKET_OVERFLOW;
        }
        label_size = wire[*pos];
        while (label_size > 0) {
                /* compression */
                while (label_size >= 192) {
                        if (compression_pos == 0) {
                                compression_pos = *pos + 2;
                        }
 
                        pointer_count++;
 
                        /* remove first two bits */
                        if (*pos + 2 > max) {
                                return LDNS_STATUS_PACKET_OVERFLOW;
                        }
                        pointer_target_buf[0] = wire[*pos] & 63;
                        pointer_target_buf[1] = wire[*pos + 1];
                        pointer_target = ldns_read_uint16(pointer_target_buf);
 
                        if (pointer_target == 0) {
                                return LDNS_STATUS_INVALID_POINTER;
                        } else if (pointer_target >= max) {
                                return LDNS_STATUS_INVALID_POINTER;
                        } else if (pointer_count > LDNS_MAX_POINTERS) {
                                return LDNS_STATUS_INVALID_POINTER;
                        }
                        *pos = pointer_target;
                        label_size = wire[*pos];
                }
                if(label_size == 0)
                        break; /* break from pointer to 0 byte */
                if (label_size > LDNS_MAX_LABELLEN) {
                        return LDNS_STATUS_LABEL_OVERFLOW;
                }
                if (*pos + 1 + label_size > max) {
                        return LDNS_STATUS_LABEL_OVERFLOW;
                }
 
                /* check space for labelcount itself */
                if (dname_pos + 1 > LDNS_MAX_DOMAINLEN) {
                        return LDNS_STATUS_DOMAINNAME_OVERFLOW;
                }
                tmp_dname[dname_pos] = label_size;
                if (label_size > 0) {
                        dname_pos++;
                }
                *pos = *pos + 1;
                if (dname_pos + label_size > LDNS_MAX_DOMAINLEN) {
                        return LDNS_STATUS_DOMAINNAME_OVERFLOW;
                }
                memcpy(&tmp_dname[dname_pos], &wire[*pos], label_size);
                uncompressed_length += label_size + 1;
                dname_pos += label_size;
                *pos = *pos + label_size;
 
                if (*pos < max) {
                        label_size = wire[*pos];
                }
        }
 
        if (compression_pos > 0) {
                *pos = compression_pos;
        } else {
                *pos = *pos + 1;
        }
 
        if (dname_pos >= LDNS_MAX_DOMAINLEN) {
                return LDNS_STATUS_DOMAINNAME_OVERFLOW;
        }
 
        tmp_dname[dname_pos] = 0;
        dname_pos++;
 
        *dname = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME,
                        (uint16_t) dname_pos, tmp_dname);
        if (!*dname) {
                return LDNS_STATUS_MEM_ERR;
        }
        return LDNS_STATUS_OK;
}
 
/* maybe make this a goto error so data can be freed or something/ */
#define LDNS_STATUS_CHECK_RETURN(st) {if (st != LDNS_STATUS_OK) { return st; }}
#define LDNS_STATUS_CHECK_GOTO(st, label) {if (st != LDNS_STATUS_OK) { /*printf("STG %s:%d: status code %d\n", __FILE__, __LINE__, st);*/  goto label; }}
 
ldns_status
ldns_wire2rdf(ldns_rr *rr, const uint8_t *wire, size_t max, size_t *pos)
{
        size_t end;
        size_t cur_rdf_length;
        uint8_t rdf_index;
        uint8_t *data;
        uint16_t rd_length;
        ldns_rdf *cur_rdf = NULL;
        ldns_rdf_type cur_rdf_type;
        const ldns_rr_descriptor *descriptor;
        ldns_status status;
 
        assert(rr != NULL);
 
        descriptor = ldns_rr_descript(ldns_rr_get_type(rr));
 
        if (*pos + 2 > max) {
                return LDNS_STATUS_PACKET_OVERFLOW;
        }
 
        rd_length = ldns_read_uint16(&wire[*pos]);
        *pos = *pos + 2;
 
        if (*pos + rd_length > max) {
                return LDNS_STATUS_PACKET_OVERFLOW;
        }
 
        end = *pos + (size_t) rd_length;
 
        rdf_index = 0;
        while (*pos < end &&
                        rdf_index < ldns_rr_descriptor_maximum(descriptor)) {
 
                cur_rdf_length = 0;
 
                cur_rdf_type = ldns_rr_descriptor_field_type(
                                descriptor, rdf_index);
 
                /* handle special cases immediately, set length
                   for fixed length rdata and do them below */
                switch (cur_rdf_type) {
                case LDNS_RDF_TYPE_DNAME:
                        status = ldns_wire2dname(&cur_rdf, wire, max, pos);
                        LDNS_STATUS_CHECK_RETURN(status);
                        break;
                case LDNS_RDF_TYPE_CLASS:
                case LDNS_RDF_TYPE_ALG:
                case LDNS_RDF_TYPE_CERTIFICATE_USAGE:
                case LDNS_RDF_TYPE_SELECTOR:
                case LDNS_RDF_TYPE_MATCHING_TYPE:
                case LDNS_RDF_TYPE_INT8:
                        cur_rdf_length = LDNS_RDF_SIZE_BYTE;
                        break;
                case LDNS_RDF_TYPE_TYPE:
                case LDNS_RDF_TYPE_INT16:
                case LDNS_RDF_TYPE_CERT_ALG:
                        cur_rdf_length = LDNS_RDF_SIZE_WORD;
                        break;
                case LDNS_RDF_TYPE_TIME:
                case LDNS_RDF_TYPE_INT32:
                case LDNS_RDF_TYPE_A:
                case LDNS_RDF_TYPE_PERIOD:
                        cur_rdf_length = LDNS_RDF_SIZE_DOUBLEWORD;
                        break;
                case LDNS_RDF_TYPE_TSIGTIME:
                case LDNS_RDF_TYPE_EUI48:
                        cur_rdf_length = LDNS_RDF_SIZE_6BYTES;
                        break;
                case LDNS_RDF_TYPE_ILNP64:
                case LDNS_RDF_TYPE_EUI64:
                        cur_rdf_length = LDNS_RDF_SIZE_8BYTES;
                        break;
                case LDNS_RDF_TYPE_AAAA:
                        cur_rdf_length = LDNS_RDF_SIZE_16BYTES;
                        break;
                case LDNS_RDF_TYPE_STR:
                case LDNS_RDF_TYPE_NSEC3_SALT:
                case LDNS_RDF_TYPE_TAG:
                        /* len is stored in first byte
                         * it should be in the rdf too, so just
                         * copy len+1 from this position
                         */
                        cur_rdf_length = ((size_t) wire[*pos]) + 1;
                        break;
 
                case LDNS_RDF_TYPE_INT16_DATA:
                        if (*pos + 2 > end) {
                                return LDNS_STATUS_PACKET_OVERFLOW;
                        }
                        cur_rdf_length =
                                (size_t) ldns_read_uint16(&wire[*pos]) + 2;
                        break;
                case LDNS_RDF_TYPE_HIP:
                        if (*pos + 4 > end) {
                                return LDNS_STATUS_PACKET_OVERFLOW;
                        }
                        cur_rdf_length =
                                (size_t) wire[*pos] + 
                                (size_t) ldns_read_uint16(&wire[*pos + 2]) + 4;
                        break;
                case LDNS_RDF_TYPE_B32_EXT:
                case LDNS_RDF_TYPE_NSEC3_NEXT_OWNER:
                        /* length is stored in first byte */
                        cur_rdf_length = ((size_t) wire[*pos]) + 1;
                        break;
                case LDNS_RDF_TYPE_APL:
                case LDNS_RDF_TYPE_B64:
                case LDNS_RDF_TYPE_HEX:
                case LDNS_RDF_TYPE_NSEC:
                case LDNS_RDF_TYPE_UNKNOWN:
                case LDNS_RDF_TYPE_SERVICE:
                case LDNS_RDF_TYPE_LOC:
                case LDNS_RDF_TYPE_WKS:
                case LDNS_RDF_TYPE_NSAP:
                case LDNS_RDF_TYPE_ATMA:
                case LDNS_RDF_TYPE_IPSECKEY:
                case LDNS_RDF_TYPE_LONG_STR:
                case LDNS_RDF_TYPE_NONE:
                        /*
                         * Read to end of rr rdata
                         */
                        cur_rdf_length = end - *pos;
                        break;
                }
 
                /* fixed length rdata */
                if (cur_rdf_length > 0) {
                        if (cur_rdf_length + *pos > end) {
                                return LDNS_STATUS_PACKET_OVERFLOW;
                        }
                        data = LDNS_XMALLOC(uint8_t, rd_length);
                        if (!data) {
                                return LDNS_STATUS_MEM_ERR;
                        }
                        memcpy(data, &wire[*pos], cur_rdf_length);
 
                        cur_rdf = ldns_rdf_new(cur_rdf_type,
                                        cur_rdf_length, data);
                        *pos = *pos + cur_rdf_length;
                }
 
                if (cur_rdf) {
                        ldns_rr_push_rdf(rr, cur_rdf);
                        cur_rdf = NULL;
                }
 
                rdf_index++;
 
        } /* while (rdf_index < ldns_rr_descriptor_maximum(descriptor)) */
 
 
        return LDNS_STATUS_OK;
}
 
 
/* TODO:
         can *pos be incremented at READ_INT? or maybe use something like
         RR_CLASS(wire)?
         uhhm Jelte??
*/
ldns_status
ldns_wire2rr(ldns_rr **rr_p, const uint8_t *wire, size_t max,
             size_t *pos, ldns_pkt_section section)
{
        ldns_rdf *owner = NULL;
        ldns_rr *rr = ldns_rr_new();
        ldns_status status;
 
        status = ldns_wire2dname(&owner, wire, max, pos);
        LDNS_STATUS_CHECK_GOTO(status, status_error);
 
        ldns_rr_set_owner(rr, owner);
 
        if (*pos + 4 > max) {
                status = LDNS_STATUS_PACKET_OVERFLOW;
                goto status_error;
        }
 
        ldns_rr_set_type(rr, ldns_read_uint16(&wire[*pos]));
        *pos = *pos + 2;
 
        ldns_rr_set_class(rr, ldns_read_uint16(&wire[*pos]));
        *pos = *pos + 2;
 
        if (section != LDNS_SECTION_QUESTION) {
                if (*pos + 4 > max) {
                        status = LDNS_STATUS_PACKET_OVERFLOW;
                        goto status_error;
                }
                ldns_rr_set_ttl(rr, ldns_read_uint32(&wire[*pos]));
 
                *pos = *pos + 4;
                status = ldns_wire2rdf(rr, wire, max, pos);
 
                LDNS_STATUS_CHECK_GOTO(status, status_error);
        ldns_rr_set_question(rr, false);
        } else {
        ldns_rr_set_question(rr, true);
    }
 
        *rr_p = rr;
        return LDNS_STATUS_OK;
 
status_error:
        ldns_rr_free(rr);
        return status;
}
 
static ldns_status
ldns_wire2pkt_hdr(ldns_pkt *packet, const uint8_t *wire, size_t max, size_t *pos)
{
        if (*pos + LDNS_HEADER_SIZE > max) {
                return LDNS_STATUS_WIRE_INCOMPLETE_HEADER;
        } else {
                ldns_pkt_set_id(packet, LDNS_ID_WIRE(wire));
                ldns_pkt_set_qr(packet, LDNS_QR_WIRE(wire));
                ldns_pkt_set_opcode(packet, LDNS_OPCODE_WIRE(wire));
                ldns_pkt_set_aa(packet, LDNS_AA_WIRE(wire));
                ldns_pkt_set_tc(packet, LDNS_TC_WIRE(wire));
                ldns_pkt_set_rd(packet, LDNS_RD_WIRE(wire));
                ldns_pkt_set_ra(packet, LDNS_RA_WIRE(wire));
                ldns_pkt_set_ad(packet, LDNS_AD_WIRE(wire));
                ldns_pkt_set_cd(packet, LDNS_CD_WIRE(wire));
                ldns_pkt_set_rcode(packet, LDNS_RCODE_WIRE(wire));
 
                ldns_pkt_set_qdcount(packet, LDNS_QDCOUNT(wire));
                ldns_pkt_set_ancount(packet, LDNS_ANCOUNT(wire));
                ldns_pkt_set_nscount(packet, LDNS_NSCOUNT(wire));
                ldns_pkt_set_arcount(packet, LDNS_ARCOUNT(wire));
 
                *pos += LDNS_HEADER_SIZE;
 
                return LDNS_STATUS_OK;
        }
}
 
ldns_status
ldns_buffer2pkt_wire(ldns_pkt **packet, const ldns_buffer *buffer)
{
        /* lazy */
        return ldns_wire2pkt(packet, ldns_buffer_begin(buffer),
                                ldns_buffer_limit(buffer));
 
}
 
ldns_status
ldns_wire2pkt(ldns_pkt **packet_p, const uint8_t *wire, size_t max)
{
        size_t pos = 0;
        uint16_t i;
        ldns_rr *rr;
        ldns_pkt *packet = ldns_pkt_new();
        ldns_status status = LDNS_STATUS_OK;
        uint8_t have_edns = 0;
 
        uint8_t data[4];
 
        status = ldns_wire2pkt_hdr(packet, wire, max, &pos);
        LDNS_STATUS_CHECK_GOTO(status, status_error);
 
        for (i = 0; i < ldns_pkt_qdcount(packet); i++) {
 
                status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_QUESTION);
                if (status == LDNS_STATUS_PACKET_OVERFLOW) {
                        status = LDNS_STATUS_WIRE_INCOMPLETE_QUESTION;
                }
                LDNS_STATUS_CHECK_GOTO(status, status_error);
                if (!ldns_rr_list_push_rr(ldns_pkt_question(packet), rr)) {
                        ldns_pkt_free(packet);
                        return LDNS_STATUS_INTERNAL_ERR;
                }
        }
        for (i = 0; i < ldns_pkt_ancount(packet); i++) {
                status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ANSWER);
                if (status == LDNS_STATUS_PACKET_OVERFLOW) {
                        status = LDNS_STATUS_WIRE_INCOMPLETE_ANSWER;
                }
                LDNS_STATUS_CHECK_GOTO(status, status_error);
                if (!ldns_rr_list_push_rr(ldns_pkt_answer(packet), rr)) {
                        ldns_pkt_free(packet);
                        return LDNS_STATUS_INTERNAL_ERR;
                }
        }
        for (i = 0; i < ldns_pkt_nscount(packet); i++) {
                status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_AUTHORITY);
                if (status == LDNS_STATUS_PACKET_OVERFLOW) {
                        status = LDNS_STATUS_WIRE_INCOMPLETE_AUTHORITY;
                }
                LDNS_STATUS_CHECK_GOTO(status, status_error);
                if (!ldns_rr_list_push_rr(ldns_pkt_authority(packet), rr)) {
                        ldns_pkt_free(packet);
                        return LDNS_STATUS_INTERNAL_ERR;
                }
        }
        for (i = 0; i < ldns_pkt_arcount(packet); i++) {
                status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ADDITIONAL);
                if (status == LDNS_STATUS_PACKET_OVERFLOW) {
                        status = LDNS_STATUS_WIRE_INCOMPLETE_ADDITIONAL;
                }
                LDNS_STATUS_CHECK_GOTO(status, status_error);
 
                if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_OPT) {
                        ldns_pkt_set_edns_udp_size(packet, ldns_rr_get_class(rr));
                        ldns_write_uint32(data, ldns_rr_ttl(rr));
                        ldns_pkt_set_edns_extended_rcode(packet, data[0]);
                        ldns_pkt_set_edns_version(packet, data[1]);
                        ldns_pkt_set_edns_z(packet, ldns_read_uint16(&data[2]));
                        /* edns might not have rdfs */
                        if (ldns_rr_rdf(rr, 0)) {
                                ldns_pkt_set_edns_data(packet, ldns_rdf_clone(ldns_rr_rdf(rr, 0)));
                        }
                        ldns_rr_free(rr);
                        have_edns += 1;
                } else if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_TSIG) {
                        ldns_pkt_set_tsig(packet, rr);
                        ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet) - 1);
                } else if (!ldns_rr_list_push_rr(ldns_pkt_additional(packet), rr)) {
                        ldns_pkt_free(packet);
                        return LDNS_STATUS_INTERNAL_ERR;
                }
        }
        ldns_pkt_set_size(packet, max);
        if(have_edns)
                ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet)
                        - have_edns);
        packet->_edns_present = have_edns;
 
        *packet_p = packet;
        return status;
 
status_error:
        ldns_pkt_free(packet);
        return status;
}