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* Copyright (c) 1995 - 2006 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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#ifdef HAVE_ARPA_NAMESER_H
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#include <arpa/nameser.h>
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#ifdef _AIX /* AIX have broken res_nsearch() in 5.1 (5.0 also ?) */
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#undef HAVE_RES_NSEARCH
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#define DECL(X) {#X, rk_ns_t_##X}
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int _resolve_debug = 0;
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int ROKEN_LIB_FUNCTION
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dns_string_to_type(const char *name)
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struct stot *p = stot;
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for(p = stot; p->name; p++)
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if(strcasecmp(name, p->name) == 0)
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const char * ROKEN_LIB_FUNCTION
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dns_type_to_string(int type)
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struct stot *p = stot;
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for(p = stot; p->name; p++)
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#if (defined(HAVE_RES_SEARCH) || defined(HAVE_RES_NSEARCH)) && defined(HAVE_DN_EXPAND)
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dns_free_rr(struct resource_record *rr)
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void ROKEN_LIB_FUNCTION
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dns_free_data(struct dns_reply *r)
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struct resource_record *rr;
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for(rr = r->head; rr;){
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struct resource_record *tmp = rr;
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parse_record(const unsigned char *data, const unsigned char *end_data,
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const unsigned char **pp, struct resource_record **ret_rr)
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struct resource_record *rr;
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int type, class, ttl;
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const unsigned char *p = *pp;
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status = dn_expand(data, end_data, p, host, sizeof(host));
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if (p + status + 10 > end_data)
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type = (p[0] << 8) | p[1];
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class = (p[0] << 8) | p[1];
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ttl = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
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size = (p[0] << 8) | p[1];
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if (p + size > end_data)
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rr = calloc(1, sizeof(*rr));
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rr->domain = strdup(host);
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if(rr->domain == NULL) {
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status = dn_expand(data, end_data, p, host, sizeof(host));
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rr->u.txt = strdup(host);
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if(rr->u.txt == NULL) {
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status = dn_expand(data, end_data, p + 2, host, sizeof(host));
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if (status + 2 > size) {
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hostlen = strlen(host);
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rr->u.mx = (struct mx_record*)malloc(sizeof(struct mx_record) +
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if(rr->u.mx == NULL) {
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rr->u.mx->preference = (p[0] << 8) | p[1];
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strlcpy(rr->u.mx->domain, host, hostlen + 1);
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status = dn_expand(data, end_data, p + 6, host, sizeof(host));
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if (status + 6 > size) {
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hostlen = strlen(host);
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(struct srv_record*)malloc(sizeof(struct srv_record) +
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if(rr->u.srv == NULL) {
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rr->u.srv->priority = (p[0] << 8) | p[1];
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rr->u.srv->weight = (p[2] << 8) | p[3];
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rr->u.srv->port = (p[4] << 8) | p[5];
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strlcpy(rr->u.srv->target, host, hostlen + 1);
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if(size == 0 || size < *p + 1) {
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rr->u.txt = (char*)malloc(*p + 1);
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if(rr->u.txt == NULL) {
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strncpy(rr->u.txt, (const char*)(p + 1), *p);
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rr->u.txt[*p] = '\0';
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rr->u.key = malloc (sizeof(*rr->u.key) + key_len - 1);
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if (rr->u.key == NULL) {
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rr->u.key->flags = (p[0] << 8) | p[1];
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rr->u.key->protocol = p[2];
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rr->u.key->algorithm = p[3];
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rr->u.key->key_len = key_len;
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memcpy (rr->u.key->key_data, p + 4, key_len);
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size_t sig_len, hostlen;
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status = dn_expand (data, end_data, p + 18, host, sizeof(host));
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if (status + 18 > size) {
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/* the signer name is placed after the sig_data, to make it
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easy to free this structure; the size calculation below
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includes the zero-termination if the structure itself.
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don't you just love C?
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sig_len = size - 18 - status;
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hostlen = strlen(host);
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rr->u.sig = malloc(sizeof(*rr->u.sig)
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+ hostlen + sig_len);
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if (rr->u.sig == NULL) {
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rr->u.sig->type = (p[0] << 8) | p[1];
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rr->u.sig->algorithm = p[2];
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rr->u.sig->labels = p[3];
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rr->u.sig->orig_ttl = (p[4] << 24) | (p[5] << 16)
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| (p[6] << 8) | p[7];
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rr->u.sig->sig_expiration = (p[8] << 24) | (p[9] << 16)
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| (p[10] << 8) | p[11];
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rr->u.sig->sig_inception = (p[12] << 24) | (p[13] << 16)
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| (p[14] << 8) | p[15];
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rr->u.sig->key_tag = (p[16] << 8) | p[17];
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rr->u.sig->sig_len = sig_len;
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memcpy (rr->u.sig->sig_data, p + 18 + status, sig_len);
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rr->u.sig->signer = &rr->u.sig->sig_data[sig_len];
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strlcpy(rr->u.sig->signer, host, hostlen + 1);
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case rk_ns_t_cert : {
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rr->u.cert = malloc (sizeof(*rr->u.cert) + cert_len - 1);
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if (rr->u.cert == NULL) {
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rr->u.cert->type = (p[0] << 8) | p[1];
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rr->u.cert->tag = (p[2] << 8) | p[3];
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rr->u.cert->algorithm = p[4];
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rr->u.cert->cert_len = cert_len;
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memcpy (rr->u.cert->cert_data, p + 5, cert_len);
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case rk_ns_t_sshfp : {
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sshfp_len = size - 2;
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rr->u.sshfp = malloc (sizeof(*rr->u.sshfp) + sshfp_len - 1);
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if (rr->u.sshfp == NULL) {
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rr->u.sshfp->algorithm = p[0];
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rr->u.sshfp->type = p[1];
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rr->u.sshfp->sshfp_len = sshfp_len;
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memcpy (rr->u.sshfp->sshfp_data, p + 2, sshfp_len);
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digest_len = size - 4;
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rr->u.ds = malloc (sizeof(*rr->u.ds) + digest_len - 1);
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if (rr->u.ds == NULL) {
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rr->u.ds->key_tag = (p[0] << 8) | p[1];
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rr->u.ds->algorithm = p[2];
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rr->u.ds->digest_type = p[3];
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rr->u.ds->digest_len = digest_len;
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memcpy (rr->u.ds->digest_data, p + 4, digest_len);
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rr->u.data = (unsigned char*)malloc(size);
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if(size != 0 && rr->u.data == NULL) {
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memcpy(rr->u.data, p, size);
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parse_reply(const unsigned char *data, size_t len)
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const unsigned char *p;
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const unsigned char *end_data = data + len;
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struct resource_record **rr;
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r = calloc(1, sizeof(*r));
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r->h.id = (p[0] << 8) | p[1];
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r->h.flags |= rk_DNS_HEADER_RESPONSE_FLAG;
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r->h.opcode = (p[2] >> 1) & 0xf;
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r->h.flags |= rk_DNS_HEADER_AUTHORITIVE_ANSWER;
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r->h.flags |= rk_DNS_HEADER_TRUNCATED_MESSAGE;
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r->h.flags |= rk_DNS_HEADER_RECURSION_DESIRED;
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r->h.flags |= rk_DNS_HEADER_RECURSION_AVAILABLE;
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r->h.flags |= rk_DNS_HEADER_AUTHORITIVE_ANSWER;
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r->h.flags |= rk_DNS_HEADER_CHECKING_DISABLED;
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r->h.response_code = (p[3] >> 4) & 0xf;
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r->h.qdcount = (p[4] << 8) | p[5];
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r->h.ancount = (p[6] << 8) | p[7];
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r->h.nscount = (p[8] << 8) | p[9];
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r->h.arcount = (p[10] << 8) | p[11];
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if(r->h.qdcount != 1) {
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status = dn_expand(data, end_data, p, host, sizeof(host));
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r->q.domain = strdup(host);
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if(r->q.domain == NULL) {
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if (p + status + 4 > end_data) {
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r->q.type = (p[0] << 8 | p[1]);
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r->q.class = (p[0] << 8 | p[1]);
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for(i = 0; i < r->h.ancount; i++) {
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if(parse_record(data, end_data, &p, rr) != 0) {
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for(i = 0; i < r->h.nscount; i++) {
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if(parse_record(data, end_data, &p, rr) != 0) {
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for(i = 0; i < r->h.arcount; i++) {
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if(parse_record(data, end_data, &p, rr) != 0) {
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#ifdef HAVE_RES_NSEARCH
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#ifdef HAVE_RES_NDESTROY
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#define rk_res_free(x) res_ndestroy(x)
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#define rk_res_free(x) res_nclose(x)
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static struct dns_reply *
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dns_lookup_int(const char *domain, int rr_class, int rr_type)
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unsigned char *reply = NULL;
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#ifdef HAVE_RES_NSEARCH
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struct __res_state state;
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memset(&state, 0, sizeof(state));
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if(res_ninit(&state))
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return NULL; /* is this the best we can do? */
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#elif defined(HAVE__RES)
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u_long old_options = 0;
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if (_resolve_debug) {
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#ifdef HAVE_RES_NSEARCH
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state.options |= RES_DEBUG;
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#elif defined(HAVE__RES)
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old_options = _res.options;
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_res.options |= RES_DEBUG;
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fprintf(stderr, "dns_lookup(%s, %d, %s), buffer size %d\n", domain,
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rr_class, dns_type_to_string(rr_type), size);
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reply = malloc(size);
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#ifdef HAVE_RES_NSEARCH
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#ifdef HAVE_RES_NSEARCH
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len = res_nsearch(&state, domain, rr_class, rr_type, reply, size);
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len = res_search(domain, rr_class, rr_type, reply, size);
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if (_resolve_debug) {
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#if defined(HAVE__RES) && !defined(HAVE_RES_NSEARCH)
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_res.options = old_options;
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fprintf(stderr, "dns_lookup(%s, %d, %s) --> %d\n",
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domain, rr_class, dns_type_to_string(rr_type), len);
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#ifdef HAVE_RES_NSEARCH
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} while (size < len && len < rk_DNS_MAX_PACKET_SIZE);
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#ifdef HAVE_RES_NSEARCH
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len = min(len, size);
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r = parse_reply(reply, len);
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struct dns_reply * ROKEN_LIB_FUNCTION
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dns_lookup(const char *domain, const char *type_name)
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type = dns_string_to_type(type_name);
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fprintf(stderr, "dns_lookup: unknown resource type: `%s'\n",
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return dns_lookup_int(domain, C_IN, type);
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compare_srv(const void *a, const void *b)
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const struct resource_record *const* aa = a, *const* bb = b;
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if((*aa)->u.srv->priority == (*bb)->u.srv->priority)
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return ((*aa)->u.srv->weight - (*bb)->u.srv->weight);
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return ((*aa)->u.srv->priority - (*bb)->u.srv->priority);
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#define random() rand()
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/* try to rearrange the srv-records by the algorithm in RFC2782 */
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void ROKEN_LIB_FUNCTION
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dns_srv_order(struct dns_reply *r)
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struct resource_record **srvs, **ss, **headp;
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struct resource_record *rr;
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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int state[256 / sizeof(int)];
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for(rr = r->head; rr; rr = rr->next)
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if(rr->type == rk_ns_t_srv)
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srvs = malloc(num_srv * sizeof(*srvs));
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return; /* XXX not much to do here */
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/* unlink all srv-records from the linked list and put them in
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for(ss = srvs, headp = &r->head; *headp; )
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if((*headp)->type == rk_ns_t_srv) {
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*headp = (*headp)->next;
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headp = &(*headp)->next;
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/* sort them by priority and weight */
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qsort(srvs, num_srv, sizeof(*srvs), compare_srv);
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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oldstate = initstate(time(NULL), (char*)state, sizeof(state));
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for(ss = srvs; ss < srvs + num_srv; ) {
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struct resource_record **ee, **tt;
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/* find the last record with the same priority and count the
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sum of all weights */
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for(sum = 0, tt = ss; tt < srvs + num_srv; tt++) {
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if((*tt)->u.srv->priority != (*ss)->u.srv->priority)
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sum += (*tt)->u.srv->weight;
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/* ss is now the first record of this priority and ee is the
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rnd = random() % (sum + 1);
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for(count = 0, tt = ss; ; tt++) {
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count += (*tt)->u.srv->weight;
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/* insert the selected record at the tail (of the head) of
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(*tt)->next = *headp;
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headp = &(*tt)->next;
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sum -= (*tt)->u.srv->weight;
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while(ss < ee && *ss == NULL)
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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#else /* NOT defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND) */
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struct dns_reply * ROKEN_LIB_FUNCTION
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dns_lookup(const char *domain, const char *type_name)
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void ROKEN_LIB_FUNCTION
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dns_free_data(struct dns_reply *r)
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void ROKEN_LIB_FUNCTION
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dns_srv_order(struct dns_reply *r)