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resolve.c
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/*
* Copyright (C) 2001-2003 FhG Fokus
* Copyright (C) 2005-2009 Voice Sistem S.R.L.
*
* This file is part of opensips, a free SIP server.
*
* opensips 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; either version 2 of the License, or
* (at your option) any later version
*
* opensips 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; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* History:
* -------
* 2003-02-13 added proto to sip_resolvehost, for SRV lookups (andrei)
* 2003-07-03 default port value set according to proto (andrei)
* 2007-01-25 support for DNS failover added (bogdan)
* 2008-07-25 support for SRV load-balancing added (bogdan)
*/
/*!
* \file
* \brief DNS resolver for OpenSIPS
*/
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include "mem/mem.h"
#include "mem/shm_mem.h"
#include "net/trans.h"
#include "resolve.h"
#include "dprint.h"
#include "ut.h"
#include "ip_addr.h"
#include "globals.h"
#include "blacklists.h"
fetch_dns_cache_f *dnscache_fetch_func=NULL;
put_dns_cache_f *dnscache_put_func=NULL;
/* stuff related to DNS failover */
#define DNS_NODE_SRV 1
#define DNS_NODE_A 2
struct dns_val {
unsigned int ival;
char *sval;
};
/* mallocs for local stuff */
#define local_malloc pkg_malloc
#define local_free pkg_free
int dns_try_ipv6=0; /*!< default off */
int dns_try_naptr=1; /*!< default on */
/* declared in globals.h */
int dns_retr_time=-1;
int dns_retr_no=-1;
int dns_servers_no=-1;
int dns_search_list=-1;
int disable_dns_blacklist=1;
static struct bl_head *failover_bl=0;
#define DNS_REVOLVER_BL_ID 17
#define DNS_REVOLVER_BL_NAME "dns"
#define DNS_BL_EXPIRE 4*60
#define MAX_BUFF_SIZE 8192
#define MAXALIASES 36
#define MAXADDRS 36
#define DNS_MAX_NAME 256
struct hostent global_he;
static char hostbuf[MAX_BUFF_SIZE];
static char *h_addr_ptrs[MAXADDRS];
static char *host_aliases[MAXALIASES];
stat_var *dns_total_queries;
stat_var *dns_slow_queries;
typedef union {
int32_t al;
char ac;
} align;
#define BOUNDED_INCR(x) \
do { \
cp += x; \
if (cp > eom) { \
LM_ERR("Bounded incr failed\n"); \
return -1; \
} \
} while (0)
#define BOUNDS_CHECK(ptr, count) \
do { \
if ((ptr) + (count) > eom) { \
LM_ERR("Bounded check failed\n"); \
return -1; \
} \
} while (0)
# define DNS_GET16(s, cp) \
do { \
uint16_t t_cp; memcpy(&t_cp, cp, sizeof(uint16_t)); \
(s) = ntohs (t_cp); \
} while (0)
# define DNS_GET32(s, cp) \
do { \
uint32_t t_cp; memcpy(&t_cp, cp, sizeof(uint32_t)); \
(s) = ntohl (t_cp); \
} while (0)
static inline unsigned int dns_get16(const u_char *src) {
unsigned int dst;
DNS_GET16(dst, src);
return dst;
}
static inline unsigned int dns_get32(const u_char *src) {
unsigned int dst;
DNS_GET32(dst, src);
return dst;
}
int get_dns_answer(union dns_query *answer,int anslen,char *qname,int qtype,int *min_ttl)
{
register const HEADER *hp;
register int n;
register const unsigned char *cp;
const char* tname;
const unsigned char *eom,*erdata;
int type, class,ttl, buflen, ancount;
int haveanswer, had_error;
char *bp,**ap,**hap;
char tbuf[DNS_MAX_NAME];
int toobig=0;
tname = qname;
global_he.h_name = NULL;
eom = answer->buff + anslen;
hp = &answer->hdr;
ancount = ntohs(hp->ancount);
bp = hostbuf;
buflen = sizeof hostbuf;
cp = answer->buff;
BOUNDED_INCR(DNS_HDR_SIZE);
n = dn_expand(answer->buff, eom, cp, bp, buflen);
if (n < 0) {
LM_ERR("Error expanding name\n");
return -1;
}
BOUNDED_INCR(n+4);
if (qtype == T_A || qtype == T_AAAA) {
n = strlen(bp) + 1;
if (n >= DNS_MAX_NAME) {
LM_ERR("Name too large\n");
return -1;
}
global_he.h_name = bp;
bp += n;
buflen -= n;
/* The qname can be abbreviated, but h_name is now absolute. */
qname = global_he.h_name;
}
ap = host_aliases;
*ap = NULL;
global_he.h_aliases = host_aliases;
hap = h_addr_ptrs;
*hap = NULL;
global_he.h_addr_list = h_addr_ptrs;
haveanswer = 0;
had_error = 0;
while (ancount-- > 0 && cp < eom && !had_error) {
n = dn_expand(answer->buff, eom, cp, bp, buflen);
if (n < 0) {
had_error++;
continue;
}
cp += n; /* name */
BOUNDS_CHECK(cp,3*2+4);
type = dns_get16(cp);
cp += 2; /* type */
class = dns_get16(cp);
cp += 2; /* class*/
ttl = dns_get32(cp);
if (ttl<*min_ttl)
*min_ttl=ttl;
cp +=4;
n = dns_get16(cp);
cp += 2; /* len */
BOUNDS_CHECK(cp, n);
erdata = cp + n;
if (class != C_IN) {
LM_ERR("Got response class != C_IN");
had_error++;
continue;
}
if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
if (ap >= &host_aliases[MAXALIASES-1])
continue;
n = dn_expand(answer->buff, eom, cp, tbuf, sizeof tbuf);
if (n < 0) {
LM_ERR("failed to expand alias\n");
had_error++;
continue;
}
cp += n;
if (cp != erdata)
return -1;
/* Store alias. */
*ap++ = bp;
n = strlen(bp) + 1;
if (n >= DNS_MAX_NAME) {
LM_ERR("alias too long\n");
had_error++;
continue;
}
bp += n;
buflen -= n;
/* Get canonical name. */
n = strlen(tbuf) + 1;
if (n > buflen || n >= DNS_MAX_NAME) {
had_error++;
continue;
}
strcpy(bp, tbuf);
global_he.h_name = bp;
bp += n;
buflen -= n;
continue;
}
if (qtype == T_PTR && type == T_CNAME) {
n = dn_expand(answer->buff, eom, cp, tbuf, sizeof tbuf);
if (n < 0) {
LM_ERR("failed to expand for t_ptr\n");
had_error++;
continue;
}
cp += n;
if (cp != erdata) {
LM_ERR("failure\n");
return -1;
}
/* Get canonical name. */
n = strlen(tbuf) + 1;
if (n > buflen || n >= DNS_MAX_NAME) {
LM_ERR("ptr name too long\n");
had_error++;
continue;
}
strcpy(bp, tbuf);
tname = bp;
bp += n;
buflen -= n;
continue;
}
if (type != qtype) {
LM_ERR("asked for %d, got %d\n",qtype,type);
cp+=n;
continue;
}
switch (type) {
case T_PTR:
if (strcasecmp(tname, bp) != 0) {
LM_ERR("asked for %s, got %s\n",tname,bp);
cp += n;
continue; /* XXX - had_error++ ? */
}
n = dn_expand(answer->buff, eom, cp, bp, buflen);
if (n < 0) {
had_error++;
break;
}
cp += n;
if (cp != erdata) {
LM_ERR("errdata err\n");
return -1;
}
if (!haveanswer)
global_he.h_name = bp;
else if (ap < &host_aliases[MAXALIASES-1])
*ap++ = bp;
else
n = -1;
if (n != -1) {
n = strlen(bp) + 1; /* for the \0 */
if (n >= MAXHOSTNAMELEN) {
had_error++;
break;
}
bp += n;
buflen -= n;
}
break;
case T_A:
case T_AAAA:
if (strcasecmp(global_he.h_name, bp) != 0) {
LM_ERR("asked for %s, got %s\n",global_he.h_name,bp);
cp += n;
continue; /* XXX - had_error++ ? */
}
if (n != global_he.h_length) {
cp += n;
continue;
}
if (!haveanswer) {
register int nn;
global_he.h_name = bp;
nn = strlen(bp) + 1;
bp += nn;
buflen -= nn;
}
buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
bp += sizeof(align) - ((u_long)bp % sizeof(align));
if (bp + n >= &hostbuf[sizeof hostbuf]) {
LM_ERR("size (%d) too big\n", n);
had_error++;
continue;
}
if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
if (!toobig++)
LM_ERR("Too many addresses (%d)\n",MAXADDRS);
cp += n;
continue;
}
memmove(*hap++ = bp, cp, n);
bp += n;
buflen -= n;
cp += n;
if (cp != erdata) {
LM_ERR("failure\n");
return -1;
}
break;
default:
LM_ERR("should never get here\n");
return -1;
}
if (!had_error)
haveanswer++;
}
if (haveanswer) {
*ap = NULL;
*hap = NULL;
if (!global_he.h_name) {
n = strlen(qname) + 1;
if (n > buflen || n >= DNS_MAX_NAME) {
LM_ERR("name too long\n");
return -1;
}
strcpy(bp, qname);
global_he.h_name = bp;
bp += n;
buflen -= n;
}
}
return 0;
}
struct hostent* own_gethostbyname2(char *name,int af)
{
int size,type;
struct hostent *cached_he;
static union dns_query buff;
int min_ttl = INT_MAX;
switch (af) {
case AF_INET:
size=4;
type=T_A;
break;
case AF_INET6:
size=16;
type=T_AAAA;
break;
default:
LM_ERR("Only A and AAAA queries\n");
return NULL;
}
cached_he = (struct hostent *)dnscache_fetch_func(name,af==AF_INET?T_A:T_AAAA,0);
if (cached_he == NULL) {
LM_DBG("not found in cache or other internal error\n");
goto query;
} else if (cached_he == (void *)-1) {
LM_DBG("previously failed query\n");
return NULL;
} else {
LM_DBG("cache hit for %s - %d\n",name,af);
return cached_he;
}
query:
global_he.h_addrtype=af;
global_he.h_length=size;
size=res_search(name, C_IN, type, buff.buff, sizeof(buff));
if (size < 0) {
LM_DBG("Domain name not found\n");
if (dnscache_put_func(name,af==AF_INET?T_A:T_AAAA,NULL,0,1,0) < 0)
LM_ERR("Failed to store %s - %d in cache\n",name,af);
return NULL;
}
if (get_dns_answer(&buff,size,name,type,&min_ttl) < 0) {
LM_ERR("Failed to get dns answer\n");
return NULL;
}
if (dnscache_put_func(name,af==AF_INET?T_A:T_AAAA,&global_he,-1,0,min_ttl) < 0)
LM_ERR("Failed to store %s - %d in cache\n",name,af);
return &global_he;
}
inline struct hostent* resolvehost(char* name, int no_ip_test)
{
static struct hostent *he = NULL;
#ifdef HAVE_GETIPNODEBYNAME
int err;
static struct hostent *he2 = NULL;
#endif
struct timeval start;
struct ip_addr *ip;
str s;
if (!no_ip_test) {
s.s = (char *)name;
s.len = strlen(name);
/* check if it's an ip address */
if ((ip = str2ip(&s)) || (ip = str2ip6(&s))) {
/* we are lucky, this is an ip address */
return ip_addr2he(&s, ip);
}
}
start_expire_timer(start, execdnsthreshold);
if (dns_try_ipv6) {
/* try ipv6 */
#ifdef HAVE_GETHOSTBYNAME2
if (dnscache_fetch_func)
he = own_gethostbyname2(name,AF_INET6);
else
he = gethostbyname2(name, AF_INET6);
#elif defined HAVE_GETIPNODEBYNAME
/* on solaris 8 getipnodebyname has a memory leak,
* after some time calls to it will fail with err=3
* solution: patch your solaris 8 installation */
if (he2) freehostent(he2);
he = he2 = getipnodebyname(name, AF_INET6, 0, &err);
#else
#error "neither gethostbyname2 or getipnodebyname present"
#endif
if (he != 0)
/* return the inet6 result if exists */
goto out;
}
if (dnscache_fetch_func)
he = own_gethostbyname2(name,AF_INET);
else
he = gethostbyname(name);
out:
_stop_expire_timer(start, execdnsthreshold, "dns",
name, strlen(name), 0, dns_slow_queries, dns_total_queries);
return he;
}
struct hostent * own_gethostbyaddr(void *addr, socklen_t len, int af)
{
const unsigned char *uaddr = (const u_char *)addr;
static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
int n;
int ret;
static union dns_query ptr_buff;
socklen_t size;
char qbuf[DNS_MAX_NAME+1];
char *qp=NULL;
int min_ttl=INT_MAX;
struct hostent *cached_he;
if (af == AF_INET6 && len == 16 &&
(!memcmp(uaddr, mapped, sizeof mapped) ||
!memcmp(uaddr, tunnelled, sizeof tunnelled))) {
/* Unmap. */
addr += sizeof mapped;
uaddr += sizeof mapped;
af = AF_INET;
len = 4;
}
switch (af) {
case AF_INET:
size = 4;
break;
case AF_INET6:
size = 16;
break;
default:
LM_ERR("unexpected af = %d\n",af);
return NULL;
}
if (size != len) {
LM_ERR("size = %d, len = %d\n",size,len);
return NULL;
}
cached_he = (struct hostent *)dnscache_fetch_func(addr,T_PTR,af==AF_INET?4:16);
if (cached_he == NULL) {
LM_DBG("not found in cache or other internal error\n");
goto query;
} else if (cached_he == (void *)-1) {
LM_DBG("previously failed query\n");
return NULL;
} else {
LM_DBG("cache hit for PTR - %d\n",af);
return cached_he;
}
query:
switch (af) {
case AF_INET:
sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
(uaddr[3] & 0xff),
(uaddr[2] & 0xff),
(uaddr[1] & 0xff),
(uaddr[0] & 0xff));
break;
case AF_INET6:
qp = qbuf;
for (n = 15; n >= 0; n--) {
qp += sprintf(qp, "%x.%x.",
uaddr[n] & 0xf,
(uaddr[n] >> 4) & 0xf);
}
strcpy(qp, "ip6.arpa");
break;
}
global_he.h_addrtype=af;
global_he.h_length=len;
ret=res_search(qbuf,C_IN,T_PTR,ptr_buff.buff,sizeof(ptr_buff.buff));
if (ret < 0) {
LM_DBG("ptr not found\n");
if (dnscache_put_func(addr,T_PTR,NULL,len,1,0) < 0)
LM_ERR("Failed to store PTR in cache\n");
return NULL;
}
if (get_dns_answer(&ptr_buff,ret,qbuf,T_PTR,&min_ttl) < 0) {
LM_ERR("Failed to get dns answer\n");
return NULL;
}
if (dnscache_put_func(addr,T_PTR,&global_he,len,0,min_ttl) < 0)
LM_ERR("Failed to store PTR in cache\n");
return &global_he;
}
struct hostent* rev_resolvehost(struct ip_addr *ip)
{
if (dnscache_fetch_func != NULL) {
return own_gethostbyaddr((char*)(ip)->u.addr, (ip)->len, (ip)->af);
} else
return gethostbyaddr((char*)(ip)->u.addr, (ip)->len, (ip)->af);
}
/*! \brief checks if ip is in host(name) and ?host(ip)=name?
* ip must be in network byte order!
* resolver = DO_DNS | DO_REV_DNS; if 0 no dns check is made
* \return 0 if equal */
int check_ip_address(struct ip_addr* ip, str *name,
unsigned short port, unsigned short proto, int resolver)
{
struct ip_addr *ip2;
struct hostent* he;
int i;
/* maybe we are lucky and host (name) is an IP */
if ( (ip2=str2ip(name))!=NULL || (ip2=str2ip6(name))!=NULL ) {
/* It's an IP :D */
if (ip_addr_cmp(ip, ip2))
return 0;
return -1;
}
/* host is not an IP, do the DNS lookups on it :(*/
if (port==0) port=SIP_PORT;
if (resolver&DO_DNS){
LM_DBG("doing dns lookup\n");
/* try all names ips */
he=sip_resolvehost(name, &port, &proto, 0, 0);
if (he && (int)ip->af==he->h_addrtype){
for(i=0;he && he->h_addr_list[i];i++){
if ( memcmp(&he->h_addr_list[i], ip->u.addr, ip->len)==0)
return 0;
}
}
}
if (resolver&DO_REV_DNS){
LM_DBG("doing rev. dns lookup\n");
/* try reverse dns */
he=rev_resolvehost(ip);
if (he && (strncmp(he->h_name, name->s, name->len)==0))
return 0;
for (i=0; he && he->h_aliases[i];i++){
if (strncmp(he->h_aliases[i],name->s, name->len)==0)
return 0;
}
}
return -1;
}
/*! \brief Initialize the DNS resolver
* retr_time - time before retransmitting (must be >0)
* retr_no - retransmissions number
* servers_no - how many dns servers will be used
* (from the one listed in /etc/resolv.conf)
* search - if 0 the search list in /etc/resolv.conf will
* be ignored (HINT: even if you don't have a
* search list in resolv.conf, it's still better
* to set search to 0, because an empty searchlist
* means in fact search "" => it takes more time)
* If any of the parameters <0, the default (system specific) value
* will be used. See also resolv.conf(5).
* \return 0 on success, -1 on error
*/
int resolv_init(void)
{
res_init();
#ifdef HAVE_RESOLV_RES
if (dns_retr_time>0)
_res.retrans=dns_retr_time;
if (dns_retr_no>0)
_res.retry=dns_retr_no;
if (dns_servers_no>=0)
_res.nscount=dns_servers_no;
if (dns_search_list==0)
_res.options&=~(RES_DEFNAMES|RES_DNSRCH);
#else
#warning "no resolv timeout support"
LM_WARN("no resolv options support - resolv options will be ignored\n");
#endif
if (register_stat("dns", "dns_total_queries", &dns_total_queries, 0) ||
register_stat("dns", "dns_slow_queries", &dns_slow_queries, 0)) {
LM_ERR("failed to register DNS stats\n");
return -1;
}
return 0;
}
/*! \brief Initialize blacklist */
int resolv_blacklist_init(void)
{
str name = str_init(DNS_REVOLVER_BL_NAME);
if (!disable_dns_blacklist) {
failover_bl = create_bl_head( DNS_REVOLVER_BL_ID,
BL_DO_EXPIRE|BL_BY_DEFAULT, 0, 0, &name);
if (failover_bl==NULL) {
LM_ERR("failed to create blacklist\n");
return -1;
}
}
return 0;
}
/*! \brief Skips over a domain name in a dns message
* (it can be a sequence of labels ending in \\0, a pointer or
* a sequence of labels ending in a pointer -- see rfc1035
* returns pointer after the domain name or null on error
*/
unsigned char* dns_skipname(unsigned char* p, unsigned char* end)
{
while(p<end) {
/* check if \0 (root label length) */
if (*p==0){
p+=1;
break;
}
/* check if we found a pointer */
if (((*p)&0xc0)==0xc0){
/* if pointer skip over it (2 bytes) & we found the end */
p+=2;
break;
}
/* normal label */
p+=*p+1;
}
return (p>=end)?0:p;
}
/*! \brief parses the srv record into a srv_rdata structure
* \param msg - pointer to the dns message
* \param end - pointer to the end of the message
* \param rdata - pointer to the rdata part of the srv answer
* \return 0 on error, or a dyn. alloc'ed srv_rdata structure
*
* SRV rdata format:
* 111111
* 0123456789012345
* +----------------+
* | priority |
* |----------------|
* | weight |
* |----------------|
* | port number |
* |----------------|
* | |
* ~ name ~
* | |
* +----------------+
*/
struct srv_rdata* dns_srv_parser( unsigned char* msg, unsigned char* end,
unsigned char* rdata)
{
struct srv_rdata* srv;
int len;
srv=0;
if ((rdata+6)>=end) goto error;
srv=(struct srv_rdata*)local_malloc(sizeof(struct srv_rdata));
if (srv==0){
LM_ERR("out of pkg memory\n");
goto error;
}
memcpy((void*)&srv->priority, rdata, 2);
memcpy((void*)&srv->weight, rdata+2, 2);
memcpy((void*)&srv->port, rdata+4, 2);
rdata+=6;
srv->priority=ntohs(srv->priority);
srv->weight=ntohs(srv->weight);
srv->port=ntohs(srv->port);
if ((len=dn_expand(msg, end, rdata, srv->name, MAX_DNS_NAME-1))==-1)
goto error;
/* add terminating 0 ? (warning: len=compressed name len) */
srv->name_len=strlen(srv->name);
return srv;
error:
if (srv) local_free(srv);
return 0;
}
/*! \brief parses the naptr record into a naptr_rdata structure
* \param msg - pointer to the dns message
* \param end - pointer to the end of the message
* \param rdata - pointer to the rdata part of the naptr answer
* \return 0 on error, or a dyn. alloc'ed naptr_rdata structure
*
* NAPTR rdata format:
* 111111
* 0123456789012345
* +----------------+
* | order |
* |----------------|
* | preference |
* |----------------|
* ~ flags ~
* | (string) |
* |----------------|
* ~ services ~
* | (string) |
* |----------------|
* ~ regexp ~
* | (string) |
* |----------------|
* ~ replacement ~
| (name) |
* +----------------+
*/
struct naptr_rdata* dns_naptr_parser( unsigned char* msg, unsigned char* end,
unsigned char* rdata)
{
struct naptr_rdata* naptr;
naptr = 0;
if ((rdata + 7) >= end)
goto error;
naptr=(struct naptr_rdata*)local_malloc(sizeof(struct naptr_rdata));
if (naptr == 0){
LM_ERR("out of pkg memory\n");
goto error;
}
memcpy((void*)&naptr->order, rdata, 2);
naptr->order=ntohs(naptr->order);
memcpy((void*)&naptr->pref, rdata + 2, 2);
naptr->pref=ntohs(naptr->pref);
naptr->flags_len = (int)rdata[4];
if ((rdata + 7 + naptr->flags_len) >= end)
goto error;
memcpy((void*)&naptr->flags, rdata + 5, naptr->flags_len);
naptr->services_len = (int)rdata[5 + naptr->flags_len];
if ((rdata + 7 + naptr->flags_len + naptr->services_len) >= end) goto error;
memcpy((void*)&naptr->services, rdata + 6 + naptr->flags_len, naptr->services_len);
naptr->regexp_len = (int)rdata[6 + naptr->flags_len + naptr->services_len];
if ((rdata + 7 + naptr->flags_len + naptr->services_len + naptr->regexp_len) >= end)
goto error;
memcpy((void*)&naptr->regexp, rdata + 7 + naptr->flags_len +
naptr->services_len, naptr->regexp_len);
rdata = rdata + 7 + naptr->flags_len + naptr->services_len + naptr->regexp_len;
naptr->repl_len=dn_expand(msg, end, rdata, naptr->repl, MAX_DNS_NAME-1);
if ( naptr->repl_len==(unsigned int)-1 )
goto error;
/* add terminating 0 ? (warning: len=compressed name len) */
return naptr;
error:
if (naptr)
local_free(naptr);
return 0;
}
/*! \brief Parses a CNAME record into a cname_rdata structure */
struct cname_rdata* dns_cname_parser( unsigned char* msg, unsigned char* end,
unsigned char* rdata)
{
struct cname_rdata* cname;
int len;
cname=0;
cname=(struct cname_rdata*)local_malloc(sizeof(struct cname_rdata));
if(cname==0){
LM_ERR("out of pkg memory\n");
goto error;
}
if ((len=dn_expand(msg, end, rdata, cname->name, MAX_DNS_NAME-1))==-1)
goto error;
return cname;
error:
if (cname) local_free(cname);
return 0;
}
/*! \brief Parses an A record rdata into an a_rdata structure
* \return 0 on error or a dyn. alloc'ed a_rdata struct
*/
struct a_rdata* dns_a_parser(unsigned char* rdata, unsigned char* end)
{
struct a_rdata* a;
if (rdata+4>=end) goto error;
a=(struct a_rdata*)local_malloc(sizeof(struct a_rdata));
if (a==0){
LM_ERR("out of pkg memory\n");
goto error;
}
memcpy(a->ip, rdata, 4);
return a;
error:
return 0;
}
/*! \brief Parses an AAAA (ipv6) record rdata into an aaaa_rdata structure
* \return 0 on error or a dyn. alloc'ed aaaa_rdata struct
*/
struct aaaa_rdata* dns_aaaa_parser(unsigned char* rdata, unsigned char* end)
{
struct aaaa_rdata* aaaa;
if (rdata+16>=end) goto error;
aaaa=(struct aaaa_rdata*)local_malloc(sizeof(struct aaaa_rdata));
if (aaaa==0){
LM_ERR("out of pkg memory\n");
goto error;
}
memcpy(aaaa->ip6, rdata, 16);
return aaaa;
error:
return 0;
}
/*! \brief Parses a TXT record into a txt_rdata structure
* \note RFC1035:
* - <character-string> is a single length octet followed by that number of characters.
* - TXT-DATA One or more <character-string>s.
*
* We only take the first string here.
*/
struct txt_rdata* dns_txt_parser( unsigned char* msg, unsigned char* end,
unsigned char* rdata)
{
struct txt_rdata* txt;
unsigned int len;
txt=0;
txt=(struct txt_rdata*)local_malloc(sizeof(struct txt_rdata));
if(txt==0){
LM_ERR("out of pkg memory\n");
goto error;
}
len = *rdata;
if (rdata + 1 + len >= end)
goto error; /* something fishy in the record */
#if 0
/* Comparison is always false because len <= 255. */
if (len >= sizeof(txt->txt))
goto error; /* not enough space? */
#endif
memcpy(txt->txt, rdata+1, len);
txt->txt[len] = 0; /* 0-terminate string */
return txt;
error:
if (txt)
local_free(txt);
return 0;
}
/*! \brief parses a EBL record into a ebl_rdata structure
*
* EBL Record
*
* 0 1 2 3 4 5 6 7
* +--+--+--+--+--+--+--+--+
* | POSITION |
* +--+--+--+--+--+--+--+--+
* / SEPARATOR /
* +--+--+--+--+--+--+--+--+
* / APEX /
* +--+--+--+--+--+--+--+--+
*/
struct ebl_rdata* dns_ebl_parser( unsigned char* msg, unsigned char* end,
unsigned char* rdata)
{
struct ebl_rdata* ebl;
int len;
ebl=0;
ebl=(struct ebl_rdata*)local_malloc(sizeof(struct ebl_rdata));
if(ebl==0){
LM_ERR("out of pkg memory\n");
goto error;
}
len = *rdata;
if (rdata + 1 + len >= end)
goto error; /* something fishy in the record */