457 lines
12 KiB
C
457 lines
12 KiB
C
/*
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* wire2host.c
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*
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* conversion routines from the wire to the host
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* format.
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* This will usually just a re-ordering of the
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* data (as we store it in network format)
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*
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* a Net::DNS like library for C
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*
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* (c) NLnet Labs, 2004-2006
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*
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* See the file LICENSE for the license
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*/
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#include <ldns/config.h>
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#include <ldns/ldns.h>
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/*#include <ldns/wire2host.h>*/
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#include <strings.h>
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#include <limits.h>
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/*
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* Set of macro's to deal with the dns message header as specified
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* in RFC1035 in portable way.
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*
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*/
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/*
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*
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* 1 1 1 1 1 1
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* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | ID |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* |QR| Opcode |AA|TC|RD|RA| Z|AD|CD| RCODE |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | QDCOUNT |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | ANCOUNT |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | NSCOUNT |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | ARCOUNT |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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*
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*/
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/* allocates memory to *dname! */
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ldns_status
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ldns_wire2dname(ldns_rdf **dname, const uint8_t *wire, size_t max, size_t *pos)
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{
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uint8_t label_size;
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uint16_t pointer_target;
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uint8_t pointer_target_buf[2];
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size_t dname_pos = 0;
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size_t uncompressed_length = 0;
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size_t compression_pos = 0;
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uint8_t tmp_dname[LDNS_MAX_DOMAINLEN];
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unsigned int pointer_count = 0;
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if (*pos >= max) {
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return LDNS_STATUS_PACKET_OVERFLOW;
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}
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label_size = wire[*pos];
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while (label_size > 0) {
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/* compression */
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while (label_size >= 192) {
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if (compression_pos == 0) {
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compression_pos = *pos + 2;
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}
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pointer_count++;
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/* remove first two bits */
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if (*pos + 2 > max) {
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return LDNS_STATUS_PACKET_OVERFLOW;
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}
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pointer_target_buf[0] = wire[*pos] & 63;
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pointer_target_buf[1] = wire[*pos + 1];
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pointer_target = ldns_read_uint16(pointer_target_buf);
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if (pointer_target == 0) {
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return LDNS_STATUS_INVALID_POINTER;
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} else if (pointer_target >= max) {
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return LDNS_STATUS_INVALID_POINTER;
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} else if (pointer_count > LDNS_MAX_POINTERS) {
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return LDNS_STATUS_INVALID_POINTER;
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}
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*pos = pointer_target;
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label_size = wire[*pos];
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}
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if(label_size == 0)
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break; /* break from pointer to 0 byte */
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if (label_size > LDNS_MAX_LABELLEN) {
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return LDNS_STATUS_LABEL_OVERFLOW;
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}
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if (*pos + 1 + label_size > max) {
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return LDNS_STATUS_LABEL_OVERFLOW;
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}
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/* check space for labelcount itself */
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if (dname_pos + 1 > LDNS_MAX_DOMAINLEN) {
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return LDNS_STATUS_DOMAINNAME_OVERFLOW;
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}
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tmp_dname[dname_pos] = label_size;
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if (label_size > 0) {
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dname_pos++;
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}
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*pos = *pos + 1;
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if (dname_pos + label_size > LDNS_MAX_DOMAINLEN) {
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return LDNS_STATUS_DOMAINNAME_OVERFLOW;
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}
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memcpy(&tmp_dname[dname_pos], &wire[*pos], label_size);
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uncompressed_length += label_size + 1;
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dname_pos += label_size;
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*pos = *pos + label_size;
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if (*pos < max) {
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label_size = wire[*pos];
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}
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}
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if (compression_pos > 0) {
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*pos = compression_pos;
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} else {
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*pos = *pos + 1;
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}
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if (dname_pos >= LDNS_MAX_DOMAINLEN) {
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return LDNS_STATUS_DOMAINNAME_OVERFLOW;
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}
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tmp_dname[dname_pos] = 0;
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dname_pos++;
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*dname = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME,
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(uint16_t) dname_pos, tmp_dname);
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if (!*dname) {
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return LDNS_STATUS_MEM_ERR;
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}
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return LDNS_STATUS_OK;
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}
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/* maybe make this a goto error so data can be freed or something/ */
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#define LDNS_STATUS_CHECK_RETURN(st) {if (st != LDNS_STATUS_OK) { return st; }}
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#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; }}
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ldns_status
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ldns_wire2rdf(ldns_rr *rr, const uint8_t *wire, size_t max, size_t *pos)
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{
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size_t end;
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size_t cur_rdf_length;
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uint8_t rdf_index;
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uint8_t *data;
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uint16_t rd_length;
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ldns_rdf *cur_rdf = NULL;
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ldns_rdf_type cur_rdf_type;
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const ldns_rr_descriptor *descriptor = ldns_rr_descript(ldns_rr_get_type(rr));
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ldns_status status;
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if (*pos + 2 > max) {
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return LDNS_STATUS_PACKET_OVERFLOW;
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}
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rd_length = ldns_read_uint16(&wire[*pos]);
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*pos = *pos + 2;
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if (*pos + rd_length > max) {
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return LDNS_STATUS_PACKET_OVERFLOW;
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}
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end = *pos + (size_t) rd_length;
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for (rdf_index = 0;
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rdf_index < ldns_rr_descriptor_maximum(descriptor); rdf_index++) {
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if (*pos >= end) {
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break;
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}
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cur_rdf_length = 0;
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cur_rdf_type = ldns_rr_descriptor_field_type(descriptor, rdf_index);
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/* handle special cases immediately, set length
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for fixed length rdata and do them below */
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switch (cur_rdf_type) {
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case LDNS_RDF_TYPE_DNAME:
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status = ldns_wire2dname(&cur_rdf, wire, max, pos);
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LDNS_STATUS_CHECK_RETURN(status);
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break;
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case LDNS_RDF_TYPE_CLASS:
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case LDNS_RDF_TYPE_ALG:
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case LDNS_RDF_TYPE_INT8:
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cur_rdf_length = LDNS_RDF_SIZE_BYTE;
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break;
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case LDNS_RDF_TYPE_TYPE:
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case LDNS_RDF_TYPE_INT16:
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case LDNS_RDF_TYPE_CERT_ALG:
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cur_rdf_length = LDNS_RDF_SIZE_WORD;
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break;
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case LDNS_RDF_TYPE_TIME:
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case LDNS_RDF_TYPE_INT32:
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case LDNS_RDF_TYPE_A:
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case LDNS_RDF_TYPE_PERIOD:
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cur_rdf_length = LDNS_RDF_SIZE_DOUBLEWORD;
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break;
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case LDNS_RDF_TYPE_TSIGTIME:
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cur_rdf_length = LDNS_RDF_SIZE_6BYTES;
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break;
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case LDNS_RDF_TYPE_AAAA:
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cur_rdf_length = LDNS_RDF_SIZE_16BYTES;
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break;
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case LDNS_RDF_TYPE_STR:
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case LDNS_RDF_TYPE_NSEC3_SALT:
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/* len is stored in first byte
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* it should be in the rdf too, so just
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* copy len+1 from this position
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*/
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cur_rdf_length = ((size_t) wire[*pos]) + 1;
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break;
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case LDNS_RDF_TYPE_INT16_DATA:
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cur_rdf_length = (size_t) ldns_read_uint16(&wire[*pos]) + 2;
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break;
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case LDNS_RDF_TYPE_B32_EXT:
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case LDNS_RDF_TYPE_NSEC3_NEXT_OWNER:
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/* length is stored in first byte */
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cur_rdf_length = ((size_t) wire[*pos]) + 1;
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break;
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case LDNS_RDF_TYPE_APL:
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case LDNS_RDF_TYPE_B64:
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case LDNS_RDF_TYPE_HEX:
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case LDNS_RDF_TYPE_NSEC:
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case LDNS_RDF_TYPE_UNKNOWN:
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case LDNS_RDF_TYPE_SERVICE:
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case LDNS_RDF_TYPE_LOC:
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case LDNS_RDF_TYPE_WKS:
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case LDNS_RDF_TYPE_NSAP:
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case LDNS_RDF_TYPE_ATMA:
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case LDNS_RDF_TYPE_IPSECKEY:
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case LDNS_RDF_TYPE_TSIG:
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case LDNS_RDF_TYPE_NONE:
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/*
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* Read to end of rr rdata
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*/
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cur_rdf_length = end - *pos;
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break;
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}
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/* fixed length rdata */
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if (cur_rdf_length > 0) {
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if (cur_rdf_length + *pos > end) {
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return LDNS_STATUS_PACKET_OVERFLOW;
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}
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data = LDNS_XMALLOC(uint8_t, rd_length);
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if (!data) {
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return LDNS_STATUS_MEM_ERR;
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}
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memcpy(data, &wire[*pos], cur_rdf_length);
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cur_rdf = ldns_rdf_new(cur_rdf_type, cur_rdf_length, data);
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*pos = *pos + cur_rdf_length;
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}
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if (cur_rdf) {
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ldns_rr_push_rdf(rr, cur_rdf);
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cur_rdf = NULL;
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}
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}
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return LDNS_STATUS_OK;
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}
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/* TODO:
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can *pos be incremented at READ_INT? or maybe use something like
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RR_CLASS(wire)?
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uhhm Jelte??
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*/
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ldns_status
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ldns_wire2rr(ldns_rr **rr_p, const uint8_t *wire, size_t max,
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size_t *pos, ldns_pkt_section section)
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{
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ldns_rdf *owner = NULL;
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ldns_rr *rr = ldns_rr_new();
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ldns_status status;
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status = ldns_wire2dname(&owner, wire, max, pos);
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LDNS_STATUS_CHECK_GOTO(status, status_error);
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ldns_rr_set_owner(rr, owner);
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if (*pos + 4 > max) {
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status = LDNS_STATUS_PACKET_OVERFLOW;
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goto status_error;
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}
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ldns_rr_set_type(rr, ldns_read_uint16(&wire[*pos]));
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*pos = *pos + 2;
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ldns_rr_set_class(rr, ldns_read_uint16(&wire[*pos]));
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*pos = *pos + 2;
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if (section != LDNS_SECTION_QUESTION) {
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if (*pos + 4 > max) {
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status = LDNS_STATUS_PACKET_OVERFLOW;
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goto status_error;
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}
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ldns_rr_set_ttl(rr, ldns_read_uint32(&wire[*pos]));
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*pos = *pos + 4;
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status = ldns_wire2rdf(rr, wire, max, pos);
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LDNS_STATUS_CHECK_GOTO(status, status_error);
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ldns_rr_set_question(rr, false);
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} else {
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ldns_rr_set_question(rr, true);
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}
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*rr_p = rr;
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return LDNS_STATUS_OK;
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status_error:
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ldns_rr_free(rr);
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return status;
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}
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static ldns_status
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ldns_wire2pkt_hdr(ldns_pkt *packet, const uint8_t *wire, size_t max, size_t *pos)
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{
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if (*pos + LDNS_HEADER_SIZE > max) {
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return LDNS_STATUS_WIRE_INCOMPLETE_HEADER;
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} else {
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ldns_pkt_set_id(packet, LDNS_ID_WIRE(wire));
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ldns_pkt_set_qr(packet, LDNS_QR_WIRE(wire));
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ldns_pkt_set_opcode(packet, LDNS_OPCODE_WIRE(wire));
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ldns_pkt_set_aa(packet, LDNS_AA_WIRE(wire));
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ldns_pkt_set_tc(packet, LDNS_TC_WIRE(wire));
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ldns_pkt_set_rd(packet, LDNS_RD_WIRE(wire));
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ldns_pkt_set_ra(packet, LDNS_RA_WIRE(wire));
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ldns_pkt_set_ad(packet, LDNS_AD_WIRE(wire));
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ldns_pkt_set_cd(packet, LDNS_CD_WIRE(wire));
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ldns_pkt_set_rcode(packet, LDNS_RCODE_WIRE(wire));
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ldns_pkt_set_qdcount(packet, LDNS_QDCOUNT(wire));
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ldns_pkt_set_ancount(packet, LDNS_ANCOUNT(wire));
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ldns_pkt_set_nscount(packet, LDNS_NSCOUNT(wire));
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ldns_pkt_set_arcount(packet, LDNS_ARCOUNT(wire));
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*pos += LDNS_HEADER_SIZE;
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return LDNS_STATUS_OK;
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}
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}
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ldns_status
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ldns_buffer2pkt_wire(ldns_pkt **packet, ldns_buffer *buffer)
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{
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/* lazy */
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return ldns_wire2pkt(packet, ldns_buffer_begin(buffer),
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ldns_buffer_limit(buffer));
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}
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ldns_status
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ldns_wire2pkt(ldns_pkt **packet_p, const uint8_t *wire, size_t max)
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{
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size_t pos = 0;
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uint16_t i;
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ldns_rr *rr;
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ldns_pkt *packet = ldns_pkt_new();
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ldns_status status = LDNS_STATUS_OK;
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int have_edns = 0;
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uint8_t data[4];
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status = ldns_wire2pkt_hdr(packet, wire, max, &pos);
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LDNS_STATUS_CHECK_GOTO(status, status_error);
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for (i = 0; i < ldns_pkt_qdcount(packet); i++) {
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status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_QUESTION);
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if (status == LDNS_STATUS_PACKET_OVERFLOW) {
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status = LDNS_STATUS_WIRE_INCOMPLETE_QUESTION;
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}
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LDNS_STATUS_CHECK_GOTO(status, status_error);
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if (!ldns_rr_list_push_rr(ldns_pkt_question(packet), rr)) {
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ldns_pkt_free(packet);
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return LDNS_STATUS_INTERNAL_ERR;
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}
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}
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for (i = 0; i < ldns_pkt_ancount(packet); i++) {
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status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ANSWER);
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if (status == LDNS_STATUS_PACKET_OVERFLOW) {
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status = LDNS_STATUS_WIRE_INCOMPLETE_ANSWER;
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}
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LDNS_STATUS_CHECK_GOTO(status, status_error);
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if (!ldns_rr_list_push_rr(ldns_pkt_answer(packet), rr)) {
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ldns_pkt_free(packet);
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return LDNS_STATUS_INTERNAL_ERR;
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}
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}
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for (i = 0; i < ldns_pkt_nscount(packet); i++) {
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status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_AUTHORITY);
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if (status == LDNS_STATUS_PACKET_OVERFLOW) {
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status = LDNS_STATUS_WIRE_INCOMPLETE_AUTHORITY;
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}
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LDNS_STATUS_CHECK_GOTO(status, status_error);
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if (!ldns_rr_list_push_rr(ldns_pkt_authority(packet), rr)) {
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ldns_pkt_free(packet);
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return LDNS_STATUS_INTERNAL_ERR;
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}
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}
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for (i = 0; i < ldns_pkt_arcount(packet); i++) {
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status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ADDITIONAL);
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if (status == LDNS_STATUS_PACKET_OVERFLOW) {
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status = LDNS_STATUS_WIRE_INCOMPLETE_ADDITIONAL;
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}
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LDNS_STATUS_CHECK_GOTO(status, status_error);
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if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_OPT) {
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ldns_pkt_set_edns_udp_size(packet, ldns_rr_get_class(rr));
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ldns_write_uint32(data, ldns_rr_ttl(rr));
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ldns_pkt_set_edns_extended_rcode(packet, data[0]);
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ldns_pkt_set_edns_version(packet, data[1]);
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ldns_pkt_set_edns_z(packet, ldns_read_uint16(&data[2]));
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/* edns might not have rdfs */
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if (ldns_rr_rdf(rr, 0)) {
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ldns_pkt_set_edns_data(packet, ldns_rdf_clone(ldns_rr_rdf(rr, 0)));
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}
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ldns_rr_free(rr);
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have_edns += 1;
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} else if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_TSIG) {
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ldns_pkt_set_tsig(packet, rr);
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ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet) - 1);
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} else if (!ldns_rr_list_push_rr(ldns_pkt_additional(packet), rr)) {
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ldns_pkt_free(packet);
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return LDNS_STATUS_INTERNAL_ERR;
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}
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}
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ldns_pkt_set_size(packet, max);
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if(have_edns)
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ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet)
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- have_edns);
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*packet_p = packet;
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return status;
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status_error:
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ldns_pkt_free(packet);
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return status;
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}
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