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addns: Async ads_dns_lookup_ns
Use dns_lookup_send/recv to get NS records Signed-off-by: Volker Lendecke <vl@samba.org> Reviewed-by: Jeremy Allison <jra@samba.org> Autobuild-User(master): Volker Lendecke <vl@samba.org> Autobuild-Date(master): Tue Jan 15 11:16:00 CET 2019 on sn-devel-144
This commit is contained in:
Volker Lendecke
parent
4b4ae005b2
commit
f2d8308c22
@ -76,140 +76,6 @@
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# define T_SRV 33
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#endif
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/*********************************************************************
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*********************************************************************/
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static bool ads_dns_parse_query( TALLOC_CTX *ctx, uint8_t *start, uint8_t *end,
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uint8_t **ptr, struct dns_query *q )
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{
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uint8_t *p = *ptr;
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char hostname[MAX_DNS_NAME_LENGTH];
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int namelen;
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ZERO_STRUCTP( q );
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if ( !start || !end || !q || !*ptr)
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return false;
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/* See RFC 1035 for details. If this fails, then return. */
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namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
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if ( namelen < 0 ) {
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return false;
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}
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p += namelen;
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q->hostname = talloc_strdup( ctx, hostname );
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/* check that we have space remaining */
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if ( PTR_DIFF(p+4, end) > 0 )
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return false;
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q->type = RSVAL( p, 0 );
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q->in_class = RSVAL( p, 2 );
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p += 4;
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*ptr = p;
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return true;
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}
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/*********************************************************************
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*********************************************************************/
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static bool ads_dns_parse_rr( TALLOC_CTX *ctx, uint8_t *start, uint8_t *end,
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uint8_t **ptr, struct dns_rr *rr )
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{
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uint8_t *p = *ptr;
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char hostname[MAX_DNS_NAME_LENGTH];
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int namelen;
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if ( !start || !end || !rr || !*ptr)
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return -1;
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ZERO_STRUCTP( rr );
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/* pull the name from the answer */
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namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
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if ( namelen < 0 ) {
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return -1;
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}
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p += namelen;
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rr->hostname = talloc_strdup( ctx, hostname );
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/* check that we have space remaining */
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if ( PTR_DIFF(p+10, end) > 0 )
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return false;
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/* pull some values and then skip onto the string */
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rr->type = RSVAL(p, 0);
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rr->in_class = RSVAL(p, 2);
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rr->ttl = RIVAL(p, 4);
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rr->rdatalen = RSVAL(p, 8);
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p += 10;
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/* sanity check the available space */
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if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
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return false;
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}
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/* save a point to the rdata for this section */
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rr->rdata = p;
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p += rr->rdatalen;
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*ptr = p;
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return true;
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}
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/*********************************************************************
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*********************************************************************/
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static bool ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8_t *start, uint8_t *end,
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uint8_t **ptr, struct dns_rr_ns *nsrec )
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{
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struct dns_rr rr;
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uint8_t *p;
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char nsname[MAX_DNS_NAME_LENGTH];
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int namelen;
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if ( !start || !end || !nsrec || !*ptr)
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return -1;
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/* Parse the RR entry. Coming out of the this, ptr is at the beginning
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of the next record */
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if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
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DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n"));
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return false;
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}
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if ( rr.type != T_NS ) {
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DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n",
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rr.type));
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return false;
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}
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p = rr.rdata;
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/* ame server hostname */
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namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
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if ( namelen < 0 ) {
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DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
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return false;
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}
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nsrec->hostname = talloc_strdup( ctx, nsname );
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return true;
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}
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/*********************************************************************
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Sort SRV record list based on weight and priority. See RFC 2782.
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*********************************************************************/
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@ -235,106 +101,6 @@ static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
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return 1;
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}
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/*********************************************************************
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Simple wrapper for a DNS query
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*********************************************************************/
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#define DNS_FAILED_WAITTIME 30
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static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
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uint8_t **buf, int *resp_length )
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{
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uint8_t *buffer = NULL;
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size_t buf_len = 0;
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int resp_len = NS_PACKETSZ;
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static time_t last_dns_check = 0;
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static NTSTATUS last_dns_status = NT_STATUS_OK;
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time_t now = time_mono(NULL);
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/* Try to prevent bursts of DNS lookups if the server is down */
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/* Protect against large clock changes */
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if ( last_dns_check > now )
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last_dns_check = 0;
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/* IF we had a DNS timeout or a bad server and we are still
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in the 30 second cache window, just return the previous
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status and save the network timeout. */
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if ( (NT_STATUS_EQUAL(last_dns_status,NT_STATUS_IO_TIMEOUT) ||
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NT_STATUS_EQUAL(last_dns_status,NT_STATUS_CONNECTION_REFUSED)) &&
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(last_dns_check+DNS_FAILED_WAITTIME) > now )
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{
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DEBUG(10,("dns_send_req: last dns check returning cached status (%s)\n",
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nt_errstr(last_dns_status) ));
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return last_dns_status;
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}
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/* Send the Query */
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do {
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if ( buffer )
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TALLOC_FREE( buffer );
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buf_len = resp_len * sizeof(uint8_t);
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if (buf_len) {
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if ((buffer = talloc_array(ctx, uint8_t, buf_len))
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== NULL ) {
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DEBUG(0,("dns_send_req: "
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"talloc() failed!\n"));
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last_dns_status = NT_STATUS_NO_MEMORY;
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last_dns_check = time_mono(NULL);
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return last_dns_status;
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}
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}
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if ((resp_len = res_query(name, C_IN, q_type, buffer, buf_len))
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< 0 ) {
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DEBUG(3,("dns_send_req: "
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"Failed to resolve %s (%s)\n",
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name, strerror(errno)));
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TALLOC_FREE( buffer );
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last_dns_status = NT_STATUS_UNSUCCESSFUL;
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if (errno == ETIMEDOUT) {
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last_dns_status = NT_STATUS_IO_TIMEOUT;
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}
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if (errno == ECONNREFUSED) {
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last_dns_status = NT_STATUS_CONNECTION_REFUSED;
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}
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last_dns_check = time_mono(NULL);
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return last_dns_status;
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}
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/* On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8)
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truncated replies never give back a resp_len > buflen
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which ends up causing DNS resolve failures on large tcp DNS replies */
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if (buf_len == resp_len) {
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if (resp_len == MAX_DNS_PACKET_SIZE) {
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DEBUG(1,("dns_send_req: DNS reply too large when resolving %s\n",
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name));
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TALLOC_FREE( buffer );
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last_dns_status = NT_STATUS_BUFFER_TOO_SMALL;
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last_dns_check = time_mono(NULL);
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return last_dns_status;
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}
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resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE);
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}
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} while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE );
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*buf = buffer;
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*resp_length = resp_len;
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last_dns_check = time_mono(NULL);
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last_dns_status = NT_STATUS_OK;
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return last_dns_status;
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}
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struct ads_dns_lookup_srv_state {
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struct dns_rr_srv *srvs;
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size_t num_srvs;
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@ -509,6 +275,118 @@ fail:
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return status;
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}
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struct ads_dns_lookup_ns_state {
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struct dns_rr_ns *nss;
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size_t num_nss;
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};
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static void ads_dns_lookup_ns_done(struct tevent_req *subreq);
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struct tevent_req *ads_dns_lookup_ns_send(TALLOC_CTX *mem_ctx,
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struct tevent_context *ev,
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const char *name)
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{
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struct tevent_req *req, *subreq;
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struct ads_dns_lookup_ns_state *state;
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req = tevent_req_create(mem_ctx, &state,
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struct ads_dns_lookup_ns_state);
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if (req == NULL) {
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return NULL;
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}
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subreq = dns_lookup_send(state, ev, NULL, name, DNS_QCLASS_IN,
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DNS_QTYPE_NS);
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if (tevent_req_nomem(subreq, req)) {
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return tevent_req_post(req, ev);
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}
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tevent_req_set_callback(subreq, ads_dns_lookup_ns_done, req);
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return req;
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}
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static void ads_dns_lookup_ns_done(struct tevent_req *subreq)
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{
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struct tevent_req *req = tevent_req_callback_data(
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subreq, struct tevent_req);
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struct ads_dns_lookup_ns_state *state = tevent_req_data(
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req, struct ads_dns_lookup_ns_state);
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int ret;
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struct dns_name_packet *reply;
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uint16_t i, idx;
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ret = dns_lookup_recv(subreq, state, &reply);
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TALLOC_FREE(subreq);
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if (ret != 0) {
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tevent_req_nterror(req, map_nt_error_from_unix_common(ret));
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return;
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}
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for (i=0; i<reply->ancount; i++) {
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if (reply->answers[i].rr_type == DNS_QTYPE_NS) {
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state->num_nss += 1;
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}
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}
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state->nss = talloc_array(state, struct dns_rr_ns, state->num_nss);
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if (tevent_req_nomem(state->nss, req)) {
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return;
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}
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idx = 0;
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for (i=0; i<reply->ancount; i++) {
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struct dns_res_rec *an = &reply->answers[i];
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if (an->rr_type != DNS_QTYPE_NS) {
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continue;
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}
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state->nss[idx].hostname = talloc_move(state->nss,
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&an->rdata.ns_record);
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idx += 1;
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}
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for (i=0; i<reply->arcount; i++) {
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struct dns_res_rec *ar = &reply->additional[i];
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struct sockaddr_storage addr;
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bool ok;
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size_t j;
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ok = dns_res_rec_get_sockaddr(ar, &addr);
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if (!ok) {
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continue;
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}
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for (j=0; j<state->num_nss; j++) {
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struct dns_rr_ns *ns = &state->nss[j];
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if (strcmp(ns->hostname, ar->name) == 0) {
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ns->ss = addr;
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}
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}
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}
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tevent_req_done(req);
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}
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NTSTATUS ads_dns_lookup_ns_recv(struct tevent_req *req,
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TALLOC_CTX *mem_ctx,
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struct dns_rr_ns **nss,
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size_t *num_nss)
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{
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struct ads_dns_lookup_ns_state *state = tevent_req_data(
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req, struct ads_dns_lookup_ns_state);
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NTSTATUS status;
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if (tevent_req_is_nterror(req, &status)) {
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return status;
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}
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*nss = talloc_move(mem_ctx, &state->nss);
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*num_nss = state->num_nss;
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tevent_req_received(req);
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return NT_STATUS_OK;
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}
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/*********************************************************************
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Simple wrapper for a DNS NS query
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*********************************************************************/
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@ -518,152 +396,30 @@ NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx,
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struct dns_rr_ns **nslist,
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int *numns)
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{
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uint8_t *buffer = NULL;
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int resp_len = 0;
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struct dns_rr_ns *nsarray = NULL;
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int query_count, answer_count, auth_count, additional_count;
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uint8_t *p;
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int rrnum;
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int idx = 0;
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NTSTATUS status;
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struct tevent_context *ev;
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struct tevent_req *req;
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NTSTATUS status = NT_STATUS_NO_MEMORY;
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size_t num_ns = 0;
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if ( !ctx || !dnsdomain || !nslist ) {
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return NT_STATUS_INVALID_PARAMETER;
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ev = samba_tevent_context_init(ctx);
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if (ev == NULL) {
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goto fail;
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}
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/* Send the request. May have to loop several times in case
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of large replies */
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status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
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if ( !NT_STATUS_IS_OK(status) ) {
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DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
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nt_errstr(status)));
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return status;
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req = ads_dns_lookup_ns_send(ev, ev, dnsdomain);
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if (req == NULL) {
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goto fail;
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}
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p = buffer;
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/* For some insane reason, the ns_initparse() et. al. routines are only
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available in libresolv.a, and not the shared lib. Who knows why....
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So we have to parse the DNS reply ourselves */
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/* Pull the answer RR's count from the header.
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* Use the NMB ordering macros */
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query_count = RSVAL( p, 4 );
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answer_count = RSVAL( p, 6 );
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auth_count = RSVAL( p, 8 );
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additional_count = RSVAL( p, 10 );
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DEBUG(4,("ads_dns_lookup_ns: "
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"%d records returned in the answer section.\n",
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answer_count));
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if (answer_count) {
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if ((nsarray = talloc_array(ctx, struct dns_rr_ns,
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answer_count)) == NULL ) {
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DEBUG(0,("ads_dns_lookup_ns: "
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"talloc() failure for %d char*'s\n",
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answer_count));
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return NT_STATUS_NO_MEMORY;
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}
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} else {
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nsarray = NULL;
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if (!tevent_req_poll_ntstatus(req, ev, &status)) {
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goto fail;
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}
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/* now skip the header */
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p += NS_HFIXEDSZ;
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/* parse the query section */
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for ( rrnum=0; rrnum<query_count; rrnum++ ) {
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struct dns_query q;
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if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len,
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&p, &q)) {
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DEBUG(1,("ads_dns_lookup_ns: "
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" Failed to parse query record!\n"));
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return NT_STATUS_UNSUCCESSFUL;
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}
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}
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/* now we are at the answer section */
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for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
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if (!ads_dns_parse_rr_ns(ctx, buffer, buffer+resp_len,
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&p, &nsarray[rrnum])) {
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DEBUG(1,("ads_dns_lookup_ns: "
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"Failed to parse answer record!\n"));
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return NT_STATUS_UNSUCCESSFUL;
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}
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}
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idx = rrnum;
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/* Parse the authority section */
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/* just skip these for now */
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for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
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struct dns_rr rr;
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if ( !ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
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&p, &rr)) {
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DEBUG(1,("ads_dns_lookup_ns: "
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"Failed to parse authority record!\n"));
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return NT_STATUS_UNSUCCESSFUL;
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}
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}
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/* Parse the additional records section */
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for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
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struct dns_rr rr;
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int i;
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if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
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&p, &rr)) {
|
||||
DEBUG(1,("ads_dns_lookup_ns: Failed "
|
||||
"to parse additional records section!\n"));
|
||||
return NT_STATUS_UNSUCCESSFUL;
|
||||
}
|
||||
|
||||
/* only interested in A records as a shortcut for having to come
|
||||
back later and lookup the name */
|
||||
|
||||
if (rr.type != T_A || rr.rdatalen != 4) {
|
||||
#if defined(HAVE_IPV6)
|
||||
if (rr.type != T_AAAA || rr.rdatalen != 16)
|
||||
#endif
|
||||
continue;
|
||||
}
|
||||
|
||||
for ( i=0; i<idx; i++ ) {
|
||||
if (strcmp(rr.hostname, nsarray[i].hostname) == 0) {
|
||||
if (rr.type == T_A) {
|
||||
struct in_addr ip;
|
||||
memcpy(&ip, rr.rdata, 4);
|
||||
in_addr_to_sockaddr_storage(
|
||||
&nsarray[i].ss,
|
||||
ip);
|
||||
}
|
||||
#if defined(HAVE_IPV6)
|
||||
if (rr.type == T_AAAA) {
|
||||
struct in6_addr ip6;
|
||||
memcpy(&ip6, rr.rdata, rr.rdatalen);
|
||||
in6_addr_to_sockaddr_storage(
|
||||
&nsarray[i].ss,
|
||||
ip6);
|
||||
}
|
||||
#endif
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
*nslist = nsarray;
|
||||
*numns = idx;
|
||||
|
||||
return NT_STATUS_OK;
|
||||
status = ads_dns_lookup_ns_recv(req, ctx, nslist, &num_ns);
|
||||
*numns = num_ns;
|
||||
fail:
|
||||
TALLOC_FREE(ev);
|
||||
return status;
|
||||
}
|
||||
|
||||
|
||||
/********************************************************************
|
||||
Query with optional sitename.
|
||||
********************************************************************/
|
||||
|
||||
@ -37,6 +37,13 @@ NTSTATUS ads_dns_lookup_srv(TALLOC_CTX *ctx,
|
||||
const char *name,
|
||||
struct dns_rr_srv **dclist,
|
||||
int *numdcs);
|
||||
struct tevent_req *ads_dns_lookup_ns_send(TALLOC_CTX *mem_ctx,
|
||||
struct tevent_context *ev,
|
||||
const char *name);
|
||||
NTSTATUS ads_dns_lookup_ns_recv(struct tevent_req *req,
|
||||
TALLOC_CTX *mem_ctx,
|
||||
struct dns_rr_ns **nss,
|
||||
size_t *num_nss);
|
||||
NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx,
|
||||
const char *dnsdomain,
|
||||
struct dns_rr_ns **nslist,
|
||||
|
||||
Loading…
Reference in New Issue
Block a user