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/*
* srv_getaddrinfo.c -- SRV support for getaddrinfo
*
* Copyright 2011 Andre Grueneberg for BinkD
*
* inspired by getsrvinfo.c, Copyright 2009 Red Hat, Inc.
* and by ruli_getaddrinfo.c, Copyright (C) 2004 Goeran Weinholt
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include "sys.h"
#include "iphdr.h"
#include "srv_gai.h"
int srv_getaddrinfo(const char *node, const char *service,
const struct addrinfo *hints,
struct addrinfo **res)
{
char *srv_name;
size_t srv_name_size;
char tgt_port[6];
#ifdef WIN32
PDNS_RECORD resp, entry;
char *tgt_name;
#else
char tgt_name[BINKD_FQDNLEN + 1];
unsigned char resp[SRVGAI_DNSRESPLEN];
ns_msg nsb;
ns_rr rrb;
int rlen, i, rrlen;
const unsigned char *p;
struct in_addr dummy_addr;
#endif
int rc;
struct addrinfo *ai, **ai_last = res;
/* we need sensible information for all parameters */
if (!node || (node && !*node) || !service || (service && !*service) ||
!hints || !res)
return getaddrinfo(node, service, hints, res);
/* only domain names are supported */
if (hints->ai_flags & AI_NUMERICHOST)
return getaddrinfo(node, service, hints, res);
/* detect IP addresses */
if ((hints->ai_family == AF_INET || hints->ai_family == AF_UNSPEC) &&
#ifdef WIN32
inet_addr(node) != INADDR_NONE
#else
inet_aton(node, &dummy_addr) != 0
#endif
)
return getaddrinfo(node, service, hints, res);
#ifdef AF_INET6
if ((hints->ai_family == AF_INET6 || hints->ai_family == AF_UNSPEC) &&
strchr(node, ':'))
return getaddrinfo(node, service, hints, res);
#endif
/* only named services are supported */
if ((hints->ai_flags & AI_NUMERICSERV) || *service == '0' ||
atoi(service) > 0)
return getaddrinfo(node, service, hints, res);
/* only TCP and UDP are supported */
if (hints->ai_socktype != SOCK_STREAM && hints->ai_socktype != SOCK_DGRAM)
return getaddrinfo(node, service, hints, res);
/* _ <service> ._ tcp . <node> \0 */
srv_name_size = 1 + strlen(service) + 2 + 3 + 1 + strlen(node) + 1;
srv_name = malloc(srv_name_size);
if (!srv_name)
return EAI_MEMORY;
/* construct domain name for SRV query */
snprintf(srv_name, srv_name_size, "_%s._%s.%s", service,
hints->ai_socktype == SOCK_STREAM ? "tcp" : "udp", node);
#ifdef WIN32
rc = DnsQuery(srv_name, DNS_TYPE_SRV, DNS_QUERY_STANDARD, NULL, &resp, NULL);
#else
rlen = res_search(srv_name, ns_c_in, ns_t_srv, resp, sizeof(resp));
#endif
free(srv_name);
/* fallback if DNS query does not return a single entry */
#ifdef WIN32
if (rc != ERROR_SUCCESS)
#else
if (rlen < 1)
#endif
return getaddrinfo(node, service, hints, res);
#ifndef WIN32
/* fallback in case we cannot parse the response */
if (ns_initparse(resp, rlen, &nsb) < 0)
return getaddrinfo(node, service, hints, res);
#endif
/* iterate through result set -- might be incomplete */
#ifdef WIN32
for (entry = resp; entry != NULL; entry = entry->pNext) {
switch (entry->wType) {
case DNS_TYPE_SRV:
snprintf(tgt_port, sizeof(tgt_port), "%d", entry->Data.SRV.wPort);
tgt_name = entry->Data.SRV.pNameTarget;
#else
for (i = 0; i < ns_msg_count(nsb, ns_s_an); i++) {
rc = ns_parserr(&nsb, ns_s_an, i, &rrb);
if (rc < 0)
continue;
if (ns_rr_class(rrb) != ns_c_in)
continue;
switch (ns_rr_type(rrb)) {
case ns_t_srv:
rrlen = ns_rr_rdlen(rrb);
if (rrlen < 8) /* 2+2+2 and at least 2 for host */
break;
/* extract host and port */
p = ns_rr_rdata(rrb);
rc = dn_expand(resp, resp+rlen, p+6, tgt_name, sizeof(tgt_name));
if (rc < 2)
break;
snprintf(tgt_port, sizeof(tgt_port), "%u",
(unsigned int)p[4] << 8 | (unsigned int)p[5]);
#endif
/* resolve and add to end of list */
if (getaddrinfo(tgt_name, tgt_port, hints, ai_last) != 0)
break;
/* get end of list */
for (ai=*ai_last; ai != NULL; ai = ai->ai_next)
ai_last = &(ai->ai_next);
break;
default: /* someone stupid might use CNAME */
break;
}
}
#ifdef WIN32
/* free result set */
DnsRecordListFree(resp, DnsFreeRecordList);
#endif
/* fallback in case no resolution via SRV is possible */
if (ai_last == res)
return getaddrinfo(node, service, hints, res);
return 0;
}
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