556 lines
13 KiB
C
556 lines
13 KiB
C
/*
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* Copyright (c) 1995 - 2001 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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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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* are met:
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*
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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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*
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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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*
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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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*
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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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* SUCH DAMAGE.
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include "roken.h"
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#ifdef HAVE_ARPA_NAMESER_H
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#include <arpa/nameser.h>
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#endif
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#ifdef HAVE_RESOLV_H
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#include <resolv.h>
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#endif
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#include "resolve.h"
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#include <assert.h>
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RCSID("$Id: resolve.c,v 1.1.1.3 2001/09/17 12:09:56 assar Exp $");
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#if defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND)
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#define DECL(X) {#X, T_##X}
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static struct stot{
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const char *name;
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int type;
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}stot[] = {
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DECL(A),
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DECL(NS),
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DECL(CNAME),
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DECL(SOA),
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DECL(PTR),
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DECL(MX),
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DECL(TXT),
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DECL(AFSDB),
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DECL(SIG),
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DECL(KEY),
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DECL(SRV),
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DECL(NAPTR),
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{NULL, 0}
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};
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int _resolve_debug = 0;
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int
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dns_string_to_type(const char *name)
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{
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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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return p->type;
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return -1;
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}
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const char *
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dns_type_to_string(int type)
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{
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struct stot *p = stot;
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for(p = stot; p->name; p++)
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if(type == p->type)
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return p->name;
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return NULL;
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}
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void
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dns_free_data(struct dns_reply *r)
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{
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struct resource_record *rr;
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if(r->q.domain)
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free(r->q.domain);
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for(rr = r->head; rr;){
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struct resource_record *tmp = rr;
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if(rr->domain)
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free(rr->domain);
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if(rr->u.data)
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free(rr->u.data);
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rr = rr->next;
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free(tmp);
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}
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free (r);
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}
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static struct dns_reply*
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parse_reply(unsigned char *data, int len)
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{
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unsigned char *p;
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char host[128];
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int status;
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struct dns_reply *r;
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struct resource_record **rr;
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r = calloc(1, sizeof(*r));
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if (r == NULL)
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return NULL;
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p = data;
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#if 0
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/* doesn't work on Crays */
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memcpy(&r->h, p, sizeof(HEADER));
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p += sizeof(HEADER);
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#else
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memcpy(&r->h, p, 12); /* XXX this will probably be mostly garbage */
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p += 12;
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#endif
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status = dn_expand(data, data + len, p, host, sizeof(host));
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if(status < 0){
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dns_free_data(r);
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return NULL;
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}
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r->q.domain = strdup(host);
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if(r->q.domain == NULL) {
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dns_free_data(r);
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return NULL;
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}
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p += status;
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r->q.type = (p[0] << 8 | p[1]);
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p += 2;
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r->q.class = (p[0] << 8 | p[1]);
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p += 2;
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rr = &r->head;
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while(p < data + len){
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int type, class, ttl, size;
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status = dn_expand(data, data + len, p, host, sizeof(host));
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if(status < 0){
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dns_free_data(r);
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return NULL;
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}
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p += status;
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type = (p[0] << 8) | p[1];
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p += 2;
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class = (p[0] << 8) | p[1];
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p += 2;
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ttl = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
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p += 4;
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size = (p[0] << 8) | p[1];
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p += 2;
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*rr = (struct resource_record*)calloc(1,
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sizeof(struct resource_record));
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if(*rr == NULL) {
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dns_free_data(r);
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return NULL;
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}
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(*rr)->domain = strdup(host);
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if((*rr)->domain == NULL) {
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dns_free_data(r);
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return NULL;
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}
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(*rr)->type = type;
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(*rr)->class = class;
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(*rr)->ttl = ttl;
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(*rr)->size = size;
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switch(type){
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case T_NS:
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case T_CNAME:
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case T_PTR:
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status = dn_expand(data, data + len, p, host, sizeof(host));
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if(status < 0){
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dns_free_data(r);
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return NULL;
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}
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(*rr)->u.txt = strdup(host);
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if((*rr)->u.txt == NULL) {
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dns_free_data(r);
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return NULL;
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}
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break;
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case T_MX:
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case T_AFSDB:{
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status = dn_expand(data, data + len, p + 2, host, sizeof(host));
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if(status < 0){
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dns_free_data(r);
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return NULL;
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}
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(*rr)->u.mx = (struct mx_record*)malloc(sizeof(struct mx_record) +
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strlen(host));
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if((*rr)->u.mx == NULL) {
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dns_free_data(r);
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return NULL;
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}
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(*rr)->u.mx->preference = (p[0] << 8) | p[1];
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strcpy((*rr)->u.mx->domain, host);
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break;
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}
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case T_SRV:{
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status = dn_expand(data, data + len, p + 6, host, sizeof(host));
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if(status < 0){
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dns_free_data(r);
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return NULL;
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}
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(*rr)->u.srv =
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(struct srv_record*)malloc(sizeof(struct srv_record) +
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strlen(host));
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if((*rr)->u.srv == NULL) {
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dns_free_data(r);
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return NULL;
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}
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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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strcpy((*rr)->u.srv->target, host);
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break;
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}
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case T_TXT:{
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(*rr)->u.txt = (char*)malloc(size + 1);
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if((*rr)->u.txt == NULL) {
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dns_free_data(r);
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return NULL;
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}
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strncpy((*rr)->u.txt, (char*)p + 1, *p);
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(*rr)->u.txt[*p] = 0;
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break;
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}
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case T_KEY : {
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size_t key_len;
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key_len = size - 4;
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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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dns_free_data (r);
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return NULL;
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}
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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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break;
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}
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case T_SIG : {
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size_t sig_len;
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status = dn_expand (data, data + len, p + 18, host, sizeof(host));
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if (status < 0) {
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dns_free_data (r);
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return NULL;
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}
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sig_len = len - 18 - status;
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(*rr)->u.sig = malloc(sizeof(*(*rr)->u.sig)
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+ strlen(host) + sig_len);
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if ((*rr)->u.sig == NULL) {
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dns_free_data (r);
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return NULL;
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}
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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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strcpy((*rr)->u.sig->signer, host);
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break;
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}
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case T_CERT : {
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size_t cert_len;
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cert_len = size - 5;
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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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dns_free_data (r);
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return NULL;
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}
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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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break;
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}
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default:
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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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dns_free_data(r);
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return NULL;
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}
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memcpy((*rr)->u.data, p, size);
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}
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p += size;
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rr = &(*rr)->next;
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}
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*rr = NULL;
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return r;
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}
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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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{
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unsigned char reply[1024];
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int len;
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struct dns_reply *r = NULL;
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u_long old_options = 0;
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if (_resolve_debug) {
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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)\n", domain,
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rr_class, dns_type_to_string(rr_type));
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}
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len = res_search(domain, rr_class, rr_type, reply, sizeof(reply));
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if (_resolve_debug) {
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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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}
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if (len >= 0)
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r = parse_reply(reply, len);
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return r;
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}
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struct dns_reply *
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dns_lookup(const char *domain, const char *type_name)
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{
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int type;
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type = dns_string_to_type(type_name);
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if(type == -1) {
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if(_resolve_debug)
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fprintf(stderr, "dns_lookup: unknown resource type: `%s'\n",
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type_name);
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return NULL;
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}
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return dns_lookup_int(domain, C_IN, type);
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}
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static int
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compare_srv(const void *a, const void *b)
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{
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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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}
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#ifndef HAVE_RANDOM
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#define random() rand()
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#endif
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/* try to rearrange the srv-records by the algorithm in RFC2782 */
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void
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dns_srv_order(struct dns_reply *r)
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{
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struct resource_record **srvs, **ss, **headp;
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struct resource_record *rr;
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int num_srv = 0;
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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char state[256], *oldstate;
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#endif
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for(rr = r->head; rr; rr = rr->next)
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if(rr->type == T_SRV)
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num_srv++;
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if(num_srv == 0)
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return;
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srvs = malloc(num_srv * sizeof(*srvs));
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if(srvs == NULL)
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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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a vector */
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for(ss = srvs, headp = &r->head; *headp; )
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if((*headp)->type == T_SRV) {
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*ss = *headp;
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*headp = (*headp)->next;
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(*ss)->next = NULL;
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ss++;
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} else
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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), state, sizeof(state));
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#endif
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headp = &r->head;
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for(ss = srvs; ss < srvs + num_srv; ) {
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int sum, rnd, count;
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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 == NULL)
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continue;
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if((*tt)->u.srv->priority != (*ss)->u.srv->priority)
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break;
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sum += (*tt)->u.srv->weight;
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}
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ee = tt;
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/* ss is now the first record of this priority and ee is the
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first of the next */
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while(ss < ee) {
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rnd = random() % (sum + 1);
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for(count = 0, tt = ss; ; tt++) {
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if(*tt == NULL)
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continue;
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count += (*tt)->u.srv->weight;
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if(count >= rnd)
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break;
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}
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assert(tt < ee);
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/* insert the selected record at the tail (of the head) of
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the list */
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(*tt)->next = *headp;
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*headp = *tt;
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headp = &(*tt)->next;
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sum -= (*tt)->u.srv->weight;
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*tt = NULL;
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while(*ss == NULL)
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ss++;
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}
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}
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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setstate(oldstate);
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#endif
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free(srvs);
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return;
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}
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#else /* NOT defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND) */
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struct dns_reply *
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dns_lookup(const char *domain, const char *type_name)
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{
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return NULL;
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}
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void
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dns_free_data(struct dns_reply *r)
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{
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}
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void
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dns_srv_order(struct dns_reply *r)
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{
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return 0;
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}
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#endif
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#ifdef TEST
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int
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main(int argc, char **argv)
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{
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struct dns_reply *r;
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struct resource_record *rr;
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r = dns_lookup(argv[1], argv[2]);
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if(r == NULL){
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printf("No reply.\n");
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return 1;
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}
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if(r->q.type == T_SRV)
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dns_srv_order(r);
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for(rr = r->head; rr;rr=rr->next){
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printf("%s %s %d ", rr->domain, dns_type_to_string(rr->type), rr->ttl);
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switch(rr->type){
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case T_NS:
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case T_CNAME:
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case T_PTR:
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printf("%s\n", (char*)rr->u.data);
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break;
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case T_A:
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printf("%s\n", inet_ntoa(*rr->u.a));
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break;
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case T_MX:
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case T_AFSDB:{
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printf("%d %s\n", rr->u.mx->preference, rr->u.mx->domain);
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break;
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}
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case T_SRV:{
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struct srv_record *srv = rr->u.srv;
|
|
printf("%d %d %d %s\n", srv->priority, srv->weight,
|
|
srv->port, srv->target);
|
|
break;
|
|
}
|
|
case T_TXT: {
|
|
printf("%s\n", rr->u.txt);
|
|
break;
|
|
}
|
|
case T_SIG : {
|
|
struct sig_record *sig = rr->u.sig;
|
|
const char *type_string = dns_type_to_string (sig->type);
|
|
|
|
printf ("type %u (%s), algorithm %u, labels %u, orig_ttl %u, sig_expiration %u, sig_inception %u, key_tag %u, signer %s\n",
|
|
sig->type, type_string ? type_string : "",
|
|
sig->algorithm, sig->labels, sig->orig_ttl,
|
|
sig->sig_expiration, sig->sig_inception, sig->key_tag,
|
|
sig->signer);
|
|
break;
|
|
}
|
|
case T_KEY : {
|
|
struct key_record *key = rr->u.key;
|
|
|
|
printf ("flags %u, protocol %u, algorithm %u\n",
|
|
key->flags, key->protocol, key->algorithm);
|
|
break;
|
|
}
|
|
default:
|
|
printf("\n");
|
|
break;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#endif
|