wire2host.c

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00001  /* 
00002  * wire2host.c
00003  *
00004  * conversion routines from the wire to the host
00005  * format.
00006  * This will usually just a re-ordering of the
00007  * data (as we store it in network format)
00008  *
00009  * a Net::DNS like library for C
00010  *
00011  * (c) NLnet Labs, 2004-2006
00012  *
00013  * See the file LICENSE for the license
00014  */
00015 
00016 
00017 #include <ldns/config.h>
00018 
00019 #include <ldns/ldns.h>
00020 /*#include <ldns/wire2host.h>*/
00021 
00022 #include <strings.h>
00023 #include <limits.h>
00024 
00025 
00026 
00027 /*
00028  * Set of macro's to deal with the dns message header as specified
00029  * in RFC1035 in portable way.
00030  *
00031  */
00032 
00033 /*
00034  *
00035  *                                    1  1  1  1  1  1
00036  *      0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
00037  *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
00038  *    |                      ID                       |
00039  *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
00040  *    |QR|   Opcode  |AA|TC|RD|RA| Z|AD|CD|   RCODE   |
00041  *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
00042  *    |                    QDCOUNT                    |
00043  *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
00044  *    |                    ANCOUNT                    |
00045  *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
00046  *    |                    NSCOUNT                    |
00047  *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
00048  *    |                    ARCOUNT                    |
00049  *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
00050  *
00051  */
00052 
00053 
00054 /* allocates memory to *dname! */
00055 ldns_status
00056 ldns_wire2dname(ldns_rdf **dname, const uint8_t *wire, size_t max, size_t *pos)
00057 {
00058         uint8_t label_size;
00059         uint16_t pointer_target;
00060         uint8_t pointer_target_buf[2];
00061         size_t dname_pos = 0;
00062         size_t uncompressed_length = 0;
00063         size_t compression_pos = 0;
00064         uint8_t tmp_dname[LDNS_MAX_DOMAINLEN];
00065         unsigned int pointer_count = 0;
00066         
00067         if (*pos >= max) {
00068                 return LDNS_STATUS_PACKET_OVERFLOW;
00069         }
00070         
00071         label_size = wire[*pos];
00072         while (label_size > 0) {
00073                 /* compression */
00074                 if (label_size >= 192) {
00075                         if (compression_pos == 0) {
00076                                 compression_pos = *pos + 2;
00077                         }
00078                         
00079                         pointer_count++;
00080                         
00081                         /* remove first two bits */
00082                         if (*pos + 2 > max) {
00083                                 return LDNS_STATUS_PACKET_OVERFLOW;
00084                         }
00085                         pointer_target_buf[0] = wire[*pos] & 63;
00086                         pointer_target_buf[1] = wire[*pos + 1];
00087                         pointer_target = ldns_read_uint16(pointer_target_buf);
00088 
00089                         if (pointer_target == 0) {
00090                                 return LDNS_STATUS_INVALID_POINTER;
00091                         } else if (pointer_target > max) {
00092                                 return LDNS_STATUS_INVALID_POINTER;
00093                         } else if (pointer_count > LDNS_MAX_POINTERS) {
00094                                 return LDNS_STATUS_INVALID_POINTER;
00095                         }
00096                         *pos = pointer_target;
00097                         label_size = wire[*pos];
00098                 }
00099                 if (label_size > LDNS_MAX_LABELLEN) {
00100                         return LDNS_STATUS_LABEL_OVERFLOW;
00101                 }
00102                 if (*pos + label_size > max) {
00103                         return LDNS_STATUS_LABEL_OVERFLOW;
00104                 }
00105                 
00106                 tmp_dname[dname_pos] = label_size;
00107                 if (label_size > 0) {
00108                         dname_pos++;
00109                 }
00110                 *pos = *pos + 1;
00111                 if (dname_pos + label_size > LDNS_MAX_DOMAINLEN) {
00112                         return LDNS_STATUS_DOMAINNAME_OVERFLOW;
00113                 }
00114                 memcpy(&tmp_dname[dname_pos], &wire[*pos], label_size);
00115                 uncompressed_length += label_size + 1;
00116                 dname_pos += label_size;
00117                 *pos = *pos + label_size;
00118 
00119                 if (*pos < max) {
00120                         label_size = wire[*pos];
00121                 }
00122         }
00123 
00124         if (compression_pos > 0) {
00125                 *pos = compression_pos;
00126         } else {
00127                 *pos = *pos + 1;
00128         }
00129 
00130         tmp_dname[dname_pos] = 0;
00131         dname_pos++;
00132         
00133         *dname = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME, 
00134                         (uint16_t) dname_pos, tmp_dname);
00135         if (!*dname) {
00136                 return LDNS_STATUS_MEM_ERR;
00137         }
00138         return LDNS_STATUS_OK;
00139 }
00140 
00141 /* maybe make this a goto error so data can be freed or something/ */
00142 #define LDNS_STATUS_CHECK_RETURN(st) {if (st != LDNS_STATUS_OK) { return st; }}
00143 #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; }}
00144 
00145 ldns_status
00146 ldns_wire2rdf(ldns_rr *rr, const uint8_t *wire, size_t max, size_t *pos)
00147 {
00148         size_t end;
00149         size_t cur_rdf_length;
00150         uint8_t rdf_index;
00151         uint8_t *data;
00152         uint16_t rd_length;
00153         ldns_rdf *cur_rdf;
00154         ldns_rdf_type cur_rdf_type;
00155         const ldns_rr_descriptor *descriptor = ldns_rr_descript(ldns_rr_get_type(rr));
00156         ldns_status status;
00157         
00158         if (*pos + 2 > max) {
00159                 return LDNS_STATUS_PACKET_OVERFLOW;
00160         }
00161 
00162         rd_length = ldns_read_uint16(&wire[*pos]);
00163         *pos = *pos + 2;
00164 
00165         if (*pos + rd_length > max) {
00166                 return LDNS_STATUS_PACKET_OVERFLOW;
00167         }
00168         
00169         end = *pos + (size_t) rd_length;
00170 
00171         for (rdf_index = 0; 
00172              rdf_index < ldns_rr_descriptor_maximum(descriptor); rdf_index++) {
00173                 if (*pos >= end) {
00174                         break;
00175                 }
00176                 cur_rdf_length = 0;
00177 
00178                 cur_rdf_type = ldns_rr_descriptor_field_type(descriptor, rdf_index);
00179                 /* handle special cases immediately, set length
00180                    for fixed length rdata and do them below */
00181                 switch (cur_rdf_type) {
00182                 case LDNS_RDF_TYPE_DNAME:
00183                         status = ldns_wire2dname(&cur_rdf, wire, max, pos);
00184                         LDNS_STATUS_CHECK_RETURN(status);
00185                         break;
00186                 case LDNS_RDF_TYPE_CLASS:
00187                 case LDNS_RDF_TYPE_ALG:
00188                 case LDNS_RDF_TYPE_INT8:
00189                         cur_rdf_length = LDNS_RDF_SIZE_BYTE;
00190                         break;
00191                 case LDNS_RDF_TYPE_TYPE:
00192                 case LDNS_RDF_TYPE_INT16:
00193                 case LDNS_RDF_TYPE_CERT_ALG:
00194                         cur_rdf_length = LDNS_RDF_SIZE_WORD;
00195                         break;
00196                 case LDNS_RDF_TYPE_TIME:
00197                 case LDNS_RDF_TYPE_INT32:
00198                 case LDNS_RDF_TYPE_A:
00199                 case LDNS_RDF_TYPE_PERIOD:
00200                         cur_rdf_length = LDNS_RDF_SIZE_DOUBLEWORD;
00201                         break;
00202                 case LDNS_RDF_TYPE_TSIGTIME:
00203                         cur_rdf_length = LDNS_RDF_SIZE_6BYTES;
00204                         break;
00205                 case LDNS_RDF_TYPE_AAAA:
00206                         cur_rdf_length = LDNS_RDF_SIZE_16BYTES;
00207                         break;
00208                 case LDNS_RDF_TYPE_STR:
00209                         /* len is stored in first byte 
00210                          * it should be in the rdf too, so just
00211                          * copy len+1 from this position
00212                          */
00213                         cur_rdf_length = ((size_t) wire[*pos]) + 1;
00214                         break;
00215                 case LDNS_RDF_TYPE_INT16_DATA:
00216                         cur_rdf_length = (size_t) ldns_read_uint16(&wire[*pos]) + 2;
00217                         break;
00218                 case LDNS_RDF_TYPE_APL:
00219                 case LDNS_RDF_TYPE_B64:
00220                 case LDNS_RDF_TYPE_HEX:
00221                 case LDNS_RDF_TYPE_NSEC:
00222                 case LDNS_RDF_TYPE_UNKNOWN:
00223                 case LDNS_RDF_TYPE_SERVICE:
00224                 case LDNS_RDF_TYPE_LOC:
00225                 case LDNS_RDF_TYPE_WKS:
00226                 case LDNS_RDF_TYPE_NSAP:
00227                 case LDNS_RDF_TYPE_IPSECKEY:
00228                 case LDNS_RDF_TYPE_TSIG:
00229                 case LDNS_RDF_TYPE_NONE:
00230                         /*
00231                          * Read to end of rr rdata
00232                          */
00233                         cur_rdf_length = end - *pos;
00234                         break;
00235                 }
00236                 /* fixed length rdata */
00237                 if (cur_rdf_length > 0) {
00238                         if (cur_rdf_length + *pos > end) {
00239                                 return LDNS_STATUS_PACKET_OVERFLOW;
00240                         }
00241                         data = LDNS_XMALLOC(uint8_t, rd_length);
00242                         if (!data) {
00243                                 return LDNS_STATUS_MEM_ERR;
00244                         }
00245                         memcpy(data, &wire[*pos], cur_rdf_length);
00246                         
00247                         cur_rdf = ldns_rdf_new(cur_rdf_type, cur_rdf_length, data);
00248                         *pos = *pos + cur_rdf_length;
00249                 }       
00250 
00251                 ldns_rr_push_rdf(rr, cur_rdf);
00252         }
00253 
00254         return LDNS_STATUS_OK;
00255 }
00256 
00257 
00258 /* TODO:
00259          can *pos be incremented at READ_INT? or maybe use something like
00260          RR_CLASS(wire)?
00261          uhhm Jelte??
00262 */
00263 ldns_status
00264 ldns_wire2rr(ldns_rr **rr_p, const uint8_t *wire, size_t max, 
00265              size_t *pos, ldns_pkt_section section)
00266 {
00267         ldns_rdf *owner = NULL;
00268         ldns_rr *rr = ldns_rr_new();
00269         ldns_status status;
00270         
00271         status = ldns_wire2dname(&owner, wire, max, pos);
00272         LDNS_STATUS_CHECK_GOTO(status, status_error);
00273 
00274         ldns_rr_set_owner(rr, owner);
00275         
00276         if (*pos + 4 > max) {
00277                 status = LDNS_STATUS_PACKET_OVERFLOW;
00278                 goto status_error;
00279         }
00280         
00281         ldns_rr_set_type(rr, ldns_read_uint16(&wire[*pos]));
00282         *pos = *pos + 2;
00283 
00284         ldns_rr_set_class(rr, ldns_read_uint16(&wire[*pos]));
00285         *pos = *pos + 2;
00286 
00287         if (section != LDNS_SECTION_QUESTION) {
00288                 if (*pos + 4 > max) {
00289                         status = LDNS_STATUS_PACKET_OVERFLOW;
00290                         goto status_error;
00291                 }
00292                 ldns_rr_set_ttl(rr, ldns_read_uint32(&wire[*pos]));     
00293         
00294                 *pos = *pos + 4;
00295                 status = ldns_wire2rdf(rr, wire, max, pos);
00296         
00297                 LDNS_STATUS_CHECK_GOTO(status, status_error);
00298         }
00299         
00300         *rr_p = rr;
00301 
00302         return LDNS_STATUS_OK;
00303         
00304 status_error:
00305         ldns_rr_free(rr);
00306         return status;
00307 }
00308 
00309 static ldns_status
00310 ldns_wire2pkt_hdr(ldns_pkt *packet, const uint8_t *wire, size_t max, size_t *pos)
00311 {
00312         if (*pos + LDNS_HEADER_SIZE > max) {
00313                 return LDNS_STATUS_WIRE_INCOMPLETE_HEADER;
00314         } else {
00315                 ldns_pkt_set_id(packet, LDNS_ID_WIRE(wire));
00316                 ldns_pkt_set_qr(packet, LDNS_QR_WIRE(wire));
00317                 ldns_pkt_set_opcode(packet, LDNS_OPCODE_WIRE(wire));
00318                 ldns_pkt_set_aa(packet, LDNS_AA_WIRE(wire));
00319                 ldns_pkt_set_tc(packet, LDNS_TC_WIRE(wire));
00320                 ldns_pkt_set_rd(packet, LDNS_RD_WIRE(wire));
00321                 ldns_pkt_set_ra(packet, LDNS_RA_WIRE(wire));
00322                 ldns_pkt_set_ad(packet, LDNS_AD_WIRE(wire));
00323                 ldns_pkt_set_cd(packet, LDNS_CD_WIRE(wire));
00324                 ldns_pkt_set_rcode(packet, LDNS_RCODE_WIRE(wire));       
00325 
00326                 ldns_pkt_set_qdcount(packet, LDNS_QDCOUNT(wire));
00327                 ldns_pkt_set_ancount(packet, LDNS_ANCOUNT(wire));
00328                 ldns_pkt_set_nscount(packet, LDNS_NSCOUNT(wire));
00329                 ldns_pkt_set_arcount(packet, LDNS_ARCOUNT(wire));
00330 
00331                 *pos += LDNS_HEADER_SIZE;
00332 
00333                 return LDNS_STATUS_OK;
00334         }
00335 }
00336 
00337 ldns_status
00338 ldns_buffer2pkt_wire(ldns_pkt **packet, ldns_buffer *buffer)
00339 {
00340         /* lazy */
00341         return ldns_wire2pkt(packet, ldns_buffer_begin(buffer),
00342                                 ldns_buffer_capacity(buffer));
00343 
00344 }
00345 
00346 ldns_status
00347 ldns_wire2pkt(ldns_pkt **packet_p, const uint8_t *wire, size_t max)
00348 {
00349         size_t pos = 0;
00350         uint16_t i;
00351         ldns_rr *rr;
00352         ldns_pkt *packet = ldns_pkt_new();
00353         ldns_status status = LDNS_STATUS_OK;
00354 
00355         uint8_t data[4];
00356 
00357         status = ldns_wire2pkt_hdr(packet, wire, max, &pos);
00358         LDNS_STATUS_CHECK_GOTO(status, status_error);
00359 
00360         for (i = 0; i < ldns_pkt_qdcount(packet); i++) {
00361 
00362                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_QUESTION);
00363                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
00364                         status = LDNS_STATUS_WIRE_INCOMPLETE_QUESTION;
00365                 }
00366                 LDNS_STATUS_CHECK_GOTO(status, status_error);
00367                 if (!ldns_rr_list_push_rr(ldns_pkt_question(packet), rr)) {
00368                         ldns_pkt_free(packet);
00369                         return LDNS_STATUS_INTERNAL_ERR;
00370                 }
00371         }
00372         for (i = 0; i < ldns_pkt_ancount(packet); i++) {
00373                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ANSWER);
00374                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
00375                         status = LDNS_STATUS_WIRE_INCOMPLETE_ANSWER;
00376                 }
00377                 LDNS_STATUS_CHECK_GOTO(status, status_error);
00378                 if (!ldns_rr_list_push_rr(ldns_pkt_answer(packet), rr)) {
00379                         ldns_pkt_free(packet);
00380                         return LDNS_STATUS_INTERNAL_ERR;
00381                 }
00382         }
00383         for (i = 0; i < ldns_pkt_nscount(packet); i++) {
00384                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_AUTHORITY);
00385                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
00386                         status = LDNS_STATUS_WIRE_INCOMPLETE_AUTHORITY;
00387                 }
00388                 LDNS_STATUS_CHECK_GOTO(status, status_error);
00389                 if (!ldns_rr_list_push_rr(ldns_pkt_authority(packet), rr)) {
00390                         ldns_pkt_free(packet);
00391                         return LDNS_STATUS_INTERNAL_ERR;
00392                 }
00393         }
00394         for (i = 0; i < ldns_pkt_arcount(packet); i++) {
00395                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ADDITIONAL);
00396                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
00397                         status = LDNS_STATUS_WIRE_INCOMPLETE_ADDITIONAL;
00398                 }
00399                 LDNS_STATUS_CHECK_GOTO(status, status_error);
00400 
00401                 if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_OPT) {
00402                         ldns_pkt_set_edns_udp_size(packet, ldns_rr_get_class(rr));
00403                         ldns_write_uint32(data, ldns_rr_ttl(rr));
00404                         ldns_pkt_set_edns_extended_rcode(packet, data[0]);
00405                         ldns_pkt_set_edns_version(packet, data[1]);
00406                         ldns_pkt_set_edns_z(packet, ldns_read_uint16(&data[2]));
00407                         /* edns might not have rdfs */
00408                         if (ldns_rr_rdf(rr, 0)) {
00409                                 ldns_pkt_set_edns_data(packet, ldns_rdf_clone(ldns_rr_rdf(rr, 0)));
00410                         }
00411                         ldns_rr_free(rr);
00412                         ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet) - 1);
00413                 } else if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_TSIG) {
00414                         ldns_pkt_set_tsig(packet, rr);
00415                         ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet) - 1);
00416                 } else if (!ldns_rr_list_push_rr(ldns_pkt_additional(packet), rr)) {
00417                         ldns_pkt_free(packet);
00418                         return LDNS_STATUS_INTERNAL_ERR;
00419                 }
00420         }
00421         ldns_pkt_set_size(packet, max);
00422 
00423         *packet_p = packet;
00424         return status;
00425         
00426 status_error:
00427         ldns_pkt_free(packet);
00428         return status;
00429 }

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