int
ares_parse_soa_reply(const unsigned char *abuf, int alen,
struct ares_soa_reply **soa_out)
{
const unsigned char *aptr;
long len;
char *qname = NULL, *rr_name = NULL;
struct ares_soa_reply *soa = NULL;
int qdcount, ancount;
int status;
if (alen < HFIXEDSZ)
return ARES_EBADRESP;
/* parse message header */
qdcount = DNS_HEADER_QDCOUNT(abuf);
ancount = DNS_HEADER_ANCOUNT(abuf);
if (qdcount != 1 || ancount != 1)
return ARES_EBADRESP;
aptr = abuf + HFIXEDSZ;
/* query name */
status = ares__expand_name_for_response(aptr, abuf, alen, &qname, &len);
if (status != ARES_SUCCESS)
goto failed_stat;
aptr += len;
/* skip qtype & qclass */
if (aptr + QFIXEDSZ > abuf + alen)
goto failed;
aptr += QFIXEDSZ;
/* rr_name */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len);
if (status != ARES_SUCCESS)
goto failed_stat;
aptr += len;
/* skip rr_type, rr_class, rr_ttl, rr_rdlen */
if (aptr + RRFIXEDSZ > abuf + alen)
goto failed;
aptr += RRFIXEDSZ;
/* allocate result struct */
soa = ares_malloc_data(ARES_DATATYPE_SOA_REPLY);
if (!soa)
{
status = ARES_ENOMEM;
goto failed_stat;
}
/* nsname */
status = ares__expand_name_for_response(aptr, abuf, alen, &soa->nsname, &len);
if (status != ARES_SUCCESS)
goto failed_stat;
aptr += len;
/* hostmaster */
status = ares__expand_name_for_response(aptr, abuf, alen, &soa->hostmaster, &len);
if (status != ARES_SUCCESS)
goto failed_stat;
aptr += len;
/* integer fields */
if (aptr + 5 * 4 > abuf + alen)
goto failed;
soa->serial = DNS__32BIT(aptr + 0 * 4);
soa->refresh = DNS__32BIT(aptr + 1 * 4);
soa->retry = DNS__32BIT(aptr + 2 * 4);
soa->expire = DNS__32BIT(aptr + 3 * 4);
soa->minttl = DNS__32BIT(aptr + 4 * 4);
free(qname);
free(rr_name);
*soa_out = soa;
return ARES_SUCCESS;
failed:
status = ARES_EBADRESP;
failed_stat:
ares_free_data(soa);
if (qname)
free(qname);
if (rr_name)
free(rr_name);
return status;
}
int ares_parse_ns_reply( const unsigned char* abuf, int alen,
struct hostent** host )
{
unsigned int qdcount, ancount;
int status, i, rr_type, rr_class, rr_len;
int nameservers_num;
long len;
const unsigned char *aptr;
char* hostname, *rr_name, *rr_data, **nameservers;
struct hostent *hostent;
/* Set *host to NULL for all failure cases. */
*host = NULL;
/* Give up if abuf doesn't have room for a header. */
if ( alen < HFIXEDSZ )
return ARES_EBADRESP;
/* Fetch the question and answer count from the header. */
qdcount = DNS_HEADER_QDCOUNT( abuf );
ancount = DNS_HEADER_ANCOUNT( abuf );
if ( qdcount != 1 )
return ARES_EBADRESP;
/* Expand the name from the question, and skip past the question. */
aptr = abuf + HFIXEDSZ;
status = ares__expand_name_for_response( aptr, abuf, alen, &hostname, &len);
if ( status != ARES_SUCCESS )
return status;
if ( aptr + len + QFIXEDSZ > abuf + alen )
{
free( hostname );
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Allocate nameservers array; ancount gives an upper bound */
nameservers = malloc( ( ancount + 1 ) * sizeof( char * ) );
if ( !nameservers )
{
free( hostname );
return ARES_ENOMEM;
}
nameservers_num = 0;
/* Examine each answer resource record (RR) in turn. */
for ( i = 0; i < ( int ) ancount; i++ )
{
/* Decode the RR up to the data field. */
status = ares__expand_name_for_response( aptr, abuf, alen, &rr_name, &len );
if ( status != ARES_SUCCESS )
break;
aptr += len;
if ( aptr + RRFIXEDSZ > abuf + alen )
{
status = ARES_EBADRESP;
free(rr_name);
break;
}
rr_type = DNS_RR_TYPE( aptr );
rr_class = DNS_RR_CLASS( aptr );
rr_len = DNS_RR_LEN( aptr );
aptr += RRFIXEDSZ;
if ( rr_class == C_IN && rr_type == T_NS )
{
/* Decode the RR data and add it to the nameservers list */
status = ares__expand_name_for_response( aptr, abuf, alen, &rr_data,
&len);
if ( status != ARES_SUCCESS )
{
free(rr_name);
break;
}
nameservers[nameservers_num] = malloc(strlen(rr_data)+1);
if (nameservers[nameservers_num]==NULL)
{
free(rr_name);
free(rr_data);
status=ARES_ENOMEM;
break;
}
strcpy(nameservers[nameservers_num],rr_data);
free(rr_data);
nameservers_num++;
}
free( rr_name );
aptr += rr_len;
if ( aptr > abuf + alen )
{
status = ARES_EBADRESP;
break;
}
}
if ( status == ARES_SUCCESS && nameservers_num == 0 )
{
status = ARES_ENODATA;
}
if ( status == ARES_SUCCESS )
{
/* We got our answer. Allocate memory to build the host entry. */
nameservers[nameservers_num] = NULL;
hostent = malloc( sizeof( struct hostent ) );
if ( hostent )
{
hostent->h_addr_list = malloc( 1 * sizeof( char * ) );
if ( hostent->h_addr_list )
{
/* Fill in the hostent and return successfully. */
hostent->h_name = hostname;
hostent->h_aliases = nameservers;
hostent->h_addrtype = AF_INET;
hostent->h_length = sizeof( struct in_addr );
hostent->h_addr_list[0] = NULL;
*host = hostent;
return ARES_SUCCESS;
}
free( hostent );
}
status = ARES_ENOMEM;
}
for ( i = 0; i < nameservers_num; i++ )
free( nameservers[i] );
free( nameservers );
free( hostname );
return status;
}
int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
struct hostent **host, struct ares_addr6ttl *addrttls,
int *naddrttls)
{
unsigned int qdcount, ancount;
int status, i, rr_type, rr_class, rr_len, rr_ttl, naddrs;
int cname_ttl = INT_MAX; /* the TTL imposed by the CNAME chain */
int naliases;
long len;
const unsigned char *aptr;
char *hostname, *rr_name, *rr_data, **aliases;
struct ares_in6_addr *addrs;
struct hostent *hostent;
const int max_addr_ttls = (addrttls && naddrttls) ? *naddrttls : 0;
/* Set *host to NULL for all failure cases. */
if (host)
*host = NULL;
/* Same with *naddrttls. */
if (naddrttls)
*naddrttls = 0;
/* Give up if abuf doesn't have room for a header. */
if (alen < HFIXEDSZ)
return ARES_EBADRESP;
/* Fetch the question and answer count from the header. */
qdcount = DNS_HEADER_QDCOUNT(abuf);
ancount = DNS_HEADER_ANCOUNT(abuf);
if (qdcount != 1)
return ARES_EBADRESP;
/* Expand the name from the question, and skip past the question. */
aptr = abuf + HFIXEDSZ;
status = ares__expand_name_for_response(aptr, abuf, alen, &hostname, &len);
if (status != ARES_SUCCESS)
return status;
if (aptr + len + QFIXEDSZ > abuf + alen)
{
free(hostname);
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Allocate addresses and aliases; ancount gives an upper bound for both. */
if (host)
{
addrs = malloc(ancount * sizeof(struct ares_in6_addr));
if (!addrs)
{
free(hostname);
return ARES_ENOMEM;
}
aliases = malloc((ancount + 1) * sizeof(char *));
if (!aliases)
{
free(hostname);
free(addrs);
return ARES_ENOMEM;
}
}
else
{
addrs = NULL;
aliases = NULL;
}
naddrs = 0;
naliases = 0;
/* Examine each answer resource record (RR) in turn. */
for (i = 0; i < (int)ancount; i++)
{
/* Decode the RR up to the data field. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len);
if (status != ARES_SUCCESS)
break;
aptr += len;
if (aptr + RRFIXEDSZ > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
rr_type = DNS_RR_TYPE(aptr);
rr_class = DNS_RR_CLASS(aptr);
rr_len = DNS_RR_LEN(aptr);
rr_ttl = DNS_RR_TTL(aptr);
aptr += RRFIXEDSZ;
if (rr_class == C_IN && rr_type == T_AAAA
&& rr_len == sizeof(struct ares_in6_addr)
&& strcasecmp(rr_name, hostname) == 0)
{
if (addrs)
{
if (aptr + sizeof(struct ares_in6_addr) > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
memcpy(&addrs[naddrs], aptr, sizeof(struct ares_in6_addr));
}
if (naddrs < max_addr_ttls)
{
struct ares_addr6ttl * const at = &addrttls[naddrs];
if (aptr + sizeof(struct ares_in6_addr) > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
memcpy(&at->ip6addr, aptr, sizeof(struct ares_in6_addr));
at->ttl = rr_ttl;
}
naddrs++;
status = ARES_SUCCESS;
}
if (rr_class == C_IN && rr_type == T_CNAME)
{
/* Record the RR name as an alias. */
if (aliases)
aliases[naliases] = rr_name;
else
free(rr_name);
naliases++;
/* Decode the RR data and replace the hostname with it. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len);
if (status != ARES_SUCCESS)
break;
free(hostname);
hostname = rr_data;
/* Take the min of the TTLs we see in the CNAME chain. */
if (cname_ttl > rr_ttl)
cname_ttl = rr_ttl;
}
else
free(rr_name);
aptr += rr_len;
if (aptr > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
}
if (status == ARES_SUCCESS && naddrs == 0)
status = ARES_ENODATA;
if (status == ARES_SUCCESS)
{
/* We got our answer. */
if (naddrttls)
{
const int n = naddrs < max_addr_ttls ? naddrs : max_addr_ttls;
for (i = 0; i < n; i++)
{
/* Ensure that each A TTL is no larger than the CNAME TTL. */
if (addrttls[i].ttl > cname_ttl)
addrttls[i].ttl = cname_ttl;
}
*naddrttls = n;
}
if (aliases)
aliases[naliases] = NULL;
if (host)
{
/* Allocate memory to build the host entry. */
hostent = malloc(sizeof(struct hostent));
if (hostent)
{
hostent->h_addr_list = malloc((naddrs + 1) * sizeof(char *));
if (hostent->h_addr_list)
{
/* Fill in the hostent and return successfully. */
hostent->h_name = hostname;
hostent->h_aliases = aliases;
hostent->h_addrtype = AF_INET6;
hostent->h_length = sizeof(struct ares_in6_addr);
for (i = 0; i < naddrs; i++)
hostent->h_addr_list[i] = (char *) &addrs[i];
hostent->h_addr_list[naddrs] = NULL;
*host = hostent;
return ARES_SUCCESS;
}
free(hostent);
}
status = ARES_ENOMEM;
}
}
if (aliases)
{
for (i = 0; i < naliases; i++)
free(aliases[i]);
free(aliases);
}
free(addrs);
free(hostname);
return status;
}
int ares_parse_ptr_reply(const unsigned char *abuf, int alen, const void *addr,
int addrlen, int family, struct hostent **host)
{
unsigned int qdcount, ancount;
int status, i, rr_type, rr_class, rr_len;
long len;
const unsigned char *aptr;
char *ptrname, *hostname, *rr_name, *rr_data;
struct hostent *hostent;
int aliascnt = 0;
int alias_alloc = 8;
char ** aliases;
/* Set *host to NULL for all failure cases. */
*host = NULL;
/* Give up if abuf doesn't have room for a header. */
if (alen < HFIXEDSZ)
return ARES_EBADRESP;
/* Fetch the question and answer count from the header. */
qdcount = DNS_HEADER_QDCOUNT(abuf);
ancount = DNS_HEADER_ANCOUNT(abuf);
if (qdcount != 1)
return ARES_EBADRESP;
/* Expand the name from the question, and skip past the question. */
aptr = abuf + HFIXEDSZ;
status = ares__expand_name_for_response(aptr, abuf, alen, &ptrname, &len);
if (status != ARES_SUCCESS)
return status;
if (aptr + len + QFIXEDSZ > abuf + alen)
{
free(ptrname);
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Examine each answer resource record (RR) in turn. */
hostname = NULL;
aliases = malloc(alias_alloc * sizeof(char *));
if (!aliases)
{
free(ptrname);
return ARES_ENOMEM;
}
for (i = 0; i < (int)ancount; i++)
{
/* Decode the RR up to the data field. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len);
if (status != ARES_SUCCESS)
break;
aptr += len;
if (aptr + RRFIXEDSZ > abuf + alen)
{
free(rr_name);
status = ARES_EBADRESP;
break;
}
rr_type = DNS_RR_TYPE(aptr);
rr_class = DNS_RR_CLASS(aptr);
rr_len = DNS_RR_LEN(aptr);
aptr += RRFIXEDSZ;
if (rr_class == C_IN && rr_type == T_PTR
&& strcasecmp(rr_name, ptrname) == 0)
{
/* Decode the RR data and set hostname to it. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len);
if (status != ARES_SUCCESS)
{
free(rr_name);
break;
}
if (hostname)
free(hostname);
hostname = rr_data;
aliases[aliascnt] = malloc((strlen(rr_data)+1) * sizeof(char));
if (!aliases[aliascnt])
{
free(rr_name);
status = ARES_ENOMEM;
break;
}
strncpy(aliases[aliascnt], rr_data, strlen(rr_data)+1);
aliascnt++;
if (aliascnt >= alias_alloc) {
char **ptr;
alias_alloc *= 2;
ptr = realloc(aliases, alias_alloc * sizeof(char *));
if(!ptr) {
free(rr_name);
status = ARES_ENOMEM;
break;
}
aliases = ptr;
}
}
if (rr_class == C_IN && rr_type == T_CNAME)
{
/* Decode the RR data and replace ptrname with it. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len);
if (status != ARES_SUCCESS)
{
free(rr_name);
break;
}
free(ptrname);
ptrname = rr_data;
}
free(rr_name);
aptr += rr_len;
if (aptr > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
}
if (status == ARES_SUCCESS && !hostname)
status = ARES_ENODATA;
if (status == ARES_SUCCESS)
{
/* We got our answer. Allocate memory to build the host entry. */
hostent = malloc(sizeof(struct hostent));
if (hostent)
{
hostent->h_addr_list = malloc(2 * sizeof(char *));
if (hostent->h_addr_list)
{
hostent->h_addr_list[0] = malloc(addrlen);
if (hostent->h_addr_list[0])
{
hostent->h_aliases = malloc((aliascnt+1) * sizeof (char *));
if (hostent->h_aliases)
{
/* Fill in the hostent and return successfully. */
hostent->h_name = hostname;
for (i=0 ; i<aliascnt ; i++)
hostent->h_aliases[i] = aliases[i];
hostent->h_aliases[aliascnt] = NULL;
hostent->h_addrtype = aresx_sitoss(family);
hostent->h_length = aresx_sitoss(addrlen);
memcpy(hostent->h_addr_list[0], addr, addrlen);
hostent->h_addr_list[1] = NULL;
*host = hostent;
free(aliases);
free(ptrname);
return ARES_SUCCESS;
}
free(hostent->h_addr_list[0]);
}
free(hostent->h_addr_list);
}
free(hostent);
}
status = ARES_ENOMEM;
}
for (i=0 ; i<aliascnt ; i++)
if (aliases[i])
free(aliases[i]);
free(aliases);
if (hostname)
free(hostname);
free(ptrname);
return status;
}
