/* Unix SMB/CIFS implementation. DNS utility library Copyright (C) Gerald (Jerry) Carter 2006. Copyright (C) Jeremy Allison 2007. 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; either version 3 of the License, or (at your option) any later version. 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. If not, see <http://www.gnu.org/licenses/>. */ #include "includes.h" #include "libads/dns.h" /* AIX resolv.h uses 'class' in struct ns_rr */ #if defined(AIX) # if defined(class) # undef class # endif #endif /* AIX */ /* resolver headers */ #include <sys/types.h> #include <netinet/in.h> #include <arpa/nameser.h> #include <resolv.h> #include <netdb.h> #define MAX_DNS_PACKET_SIZE 0xffff #ifdef NS_HFIXEDSZ /* Bind 8/9 interface */ #if !defined(C_IN) /* AIX 5.3 already defines C_IN */ # define C_IN ns_c_in #endif #if !defined(T_A) /* AIX 5.3 already defines T_A */ # define T_A ns_t_a #endif #if defined(HAVE_IPV6) #if !defined(T_AAAA) # define T_AAAA ns_t_aaaa #endif #endif # define T_SRV ns_t_srv #if !defined(T_NS) /* AIX 5.3 already defines T_NS */ # define T_NS ns_t_ns #endif #else # ifdef HFIXEDSZ # define NS_HFIXEDSZ HFIXEDSZ # else # define NS_HFIXEDSZ sizeof(HEADER) # endif /* HFIXEDSZ */ # ifdef PACKETSZ # define NS_PACKETSZ PACKETSZ # else /* 512 is usually the default */ # define NS_PACKETSZ 512 # endif /* PACKETSZ */ # define T_SRV 33 #endif /********************************************************************* *********************************************************************/ static bool ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end, uint8 **ptr, struct dns_query *q ) { uint8 *p = *ptr; char hostname[MAX_DNS_NAME_LENGTH]; int namelen; ZERO_STRUCTP( q ); if ( !start || !end || !q || !*ptr) return False; /* See RFC 1035 for details. If this fails, then return. */ namelen = dn_expand( start, end, p, hostname, sizeof(hostname) ); if ( namelen < 0 ) { return False; } p += namelen; q->hostname = talloc_strdup( ctx, hostname ); /* check that we have space remaining */ if ( PTR_DIFF(p+4, end) > 0 ) return False; q->type = RSVAL( p, 0 ); q->in_class = RSVAL( p, 2 ); p += 4; *ptr = p; return True; } /********************************************************************* *********************************************************************/ static bool ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end, uint8 **ptr, struct dns_rr *rr ) { uint8 *p = *ptr; char hostname[MAX_DNS_NAME_LENGTH]; int namelen; if ( !start || !end || !rr || !*ptr) return -1; ZERO_STRUCTP( rr ); /* pull the name from the answer */ namelen = dn_expand( start, end, p, hostname, sizeof(hostname) ); if ( namelen < 0 ) { return -1; } p += namelen; rr->hostname = talloc_strdup( ctx, hostname ); /* check that we have space remaining */ if ( PTR_DIFF(p+10, end) > 0 ) return False; /* pull some values and then skip onto the string */ rr->type = RSVAL(p, 0); rr->in_class = RSVAL(p, 2); rr->ttl = RIVAL(p, 4); rr->rdatalen = RSVAL(p, 8); p += 10; /* sanity check the available space */ if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) { return False; } /* save a point to the rdata for this section */ rr->rdata = p; p += rr->rdatalen; *ptr = p; return True; } /********************************************************************* *********************************************************************/ static bool ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end, uint8 **ptr, struct dns_rr_srv *srv ) { struct dns_rr rr; uint8 *p; char dcname[MAX_DNS_NAME_LENGTH]; int namelen; if ( !start || !end || !srv || !*ptr) return -1; /* Parse the RR entry. Coming out of the this, ptr is at the beginning of the next record */ if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) { DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n")); return False; } if ( rr.type != T_SRV ) { DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n", rr.type)); return False; } p = rr.rdata; srv->priority = RSVAL(p, 0); srv->weight = RSVAL(p, 2); srv->port = RSVAL(p, 4); p += 6; namelen = dn_expand( start, end, p, dcname, sizeof(dcname) ); if ( namelen < 0 ) { DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n")); return False; } srv->hostname = talloc_strdup( ctx, dcname ); DEBUG(10,("ads_dns_parse_rr_srv: Parsed %s [%u, %u, %u]\n", srv->hostname, srv->priority, srv->weight, srv->port)); return True; } /********************************************************************* *********************************************************************/ static bool ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8 *start, uint8 *end, uint8 **ptr, struct dns_rr_ns *nsrec ) { struct dns_rr rr; uint8 *p; char nsname[MAX_DNS_NAME_LENGTH]; int namelen; if ( !start || !end || !nsrec || !*ptr) return -1; /* Parse the RR entry. Coming out of the this, ptr is at the beginning of the next record */ if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) { DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n")); return False; } if ( rr.type != T_NS ) { DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n", rr.type)); return False; } p = rr.rdata; /* ame server hostname */ namelen = dn_expand( start, end, p, nsname, sizeof(nsname) ); if ( namelen < 0 ) { DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n")); return False; } nsrec->hostname = talloc_strdup( ctx, nsname ); return True; } /********************************************************************* Sort SRV record list based on weight and priority. See RFC 2782. *********************************************************************/ static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b ) { if ( a->priority == b->priority ) { /* randomize entries with an equal weight and priority */ if ( a->weight == b->weight ) return 0; /* higher weights should be sorted lower */ if ( a->weight > b->weight ) return -1; else return 1; } if ( a->priority < b->priority ) return -1; return 1; } /********************************************************************* Simple wrapper for a DNS query *********************************************************************/ #define DNS_FAILED_WAITTIME 30 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type, uint8 **buf, int *resp_length ) { uint8 *buffer = NULL; size_t buf_len = 0; int resp_len = NS_PACKETSZ; static time_t last_dns_check = 0; static NTSTATUS last_dns_status = NT_STATUS_OK; time_t now = time_mono(NULL); /* Try to prevent bursts of DNS lookups if the server is down */ /* Protect against large clock changes */ if ( last_dns_check > now ) last_dns_check = 0; /* IF we had a DNS timeout or a bad server and we are still in the 30 second cache window, just return the previous status and save the network timeout. */ if ( (NT_STATUS_EQUAL(last_dns_status,NT_STATUS_IO_TIMEOUT) || NT_STATUS_EQUAL(last_dns_status,NT_STATUS_CONNECTION_REFUSED)) && (last_dns_check+DNS_FAILED_WAITTIME) > now ) { DEBUG(10,("last_dns_check: Returning cached status (%s)\n", nt_errstr(last_dns_status) )); return last_dns_status; } /* Send the Query */ do { if ( buffer ) TALLOC_FREE( buffer ); buf_len = resp_len * sizeof(uint8); if (buf_len) { if ((buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) { DEBUG(0,("ads_dns_lookup_srv: " "talloc() failed!\n")); last_dns_status = NT_STATUS_NO_MEMORY; last_dns_check = time_mono(NULL); return last_dns_status; } } if ((resp_len = res_query(name, C_IN, q_type, buffer, buf_len)) < 0 ) { DEBUG(3,("ads_dns_lookup_srv: " "Failed to resolve %s (%s)\n", name, strerror(errno))); TALLOC_FREE( buffer ); last_dns_status = NT_STATUS_UNSUCCESSFUL; if (errno == ETIMEDOUT) { last_dns_status = NT_STATUS_IO_TIMEOUT; } if (errno == ECONNREFUSED) { last_dns_status = NT_STATUS_CONNECTION_REFUSED; } last_dns_check = time_mono(NULL); return last_dns_status; } /* On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8) truncated replies never give back a resp_len > buflen which ends up causing DNS resolve failures on large tcp DNS replies */ if (buf_len == resp_len) { if (resp_len == MAX_DNS_PACKET_SIZE) { DEBUG(1,("dns_send_req: DNS reply too large when resolving %s\n", name)); TALLOC_FREE( buffer ); last_dns_status = NT_STATUS_BUFFER_TOO_SMALL; last_dns_check = time_mono(NULL); return last_dns_status; } resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE); } } while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE ); *buf = buffer; *resp_length = resp_len; last_dns_check = time_mono(NULL); last_dns_status = NT_STATUS_OK; return last_dns_status; } /********************************************************************* Simple wrapper for a DNS SRV query *********************************************************************/ static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dns_rr_srv **dclist, int *numdcs) { uint8 *buffer = NULL; int resp_len = 0; struct dns_rr_srv *dcs = NULL; int query_count, answer_count, auth_count, additional_count; uint8 *p = buffer; int rrnum; int idx = 0; NTSTATUS status; if ( !ctx || !name || !dclist ) { return NT_STATUS_INVALID_PARAMETER; } /* Send the request. May have to loop several times in case of large replies */ status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len ); if ( !NT_STATUS_IS_OK(status) ) { DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n", nt_errstr(status))); return status; } p = buffer; /* For some insane reason, the ns_initparse() et. al. routines are only available in libresolv.a, and not the shared lib. Who knows why.... So we have to parse the DNS reply ourselves */ /* Pull the answer RR's count from the header. * Use the NMB ordering macros */ query_count = RSVAL( p, 4 ); answer_count = RSVAL( p, 6 ); auth_count = RSVAL( p, 8 ); additional_count = RSVAL( p, 10 ); DEBUG(4,("ads_dns_lookup_srv: " "%d records returned in the answer section.\n", answer_count)); if (answer_count) { if ((dcs = TALLOC_ZERO_ARRAY(ctx, struct dns_rr_srv, answer_count)) == NULL ) { DEBUG(0,("ads_dns_lookup_srv: " "talloc() failure for %d char*'s\n", answer_count)); return NT_STATUS_NO_MEMORY; } } else { dcs = NULL; } /* now skip the header */ p += NS_HFIXEDSZ; /* parse the query section */ for ( rrnum=0; rrnum<query_count; rrnum++ ) { struct dns_query q; if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len, &p, &q)) { DEBUG(1,("ads_dns_lookup_srv: " "Failed to parse query record [%d]!\n", rrnum)); return NT_STATUS_UNSUCCESSFUL; } } /* now we are at the answer section */ for ( rrnum=0; rrnum<answer_count; rrnum++ ) { if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len, &p, &dcs[rrnum])) { DEBUG(1,("ads_dns_lookup_srv: " "Failed to parse answer recordi [%d]!\n", rrnum)); return NT_STATUS_UNSUCCESSFUL; } } idx = rrnum; /* Parse the authority section */ /* just skip these for now */ for ( rrnum=0; rrnum<auth_count; rrnum++ ) { struct dns_rr rr; if (!ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr)) { DEBUG(1,("ads_dns_lookup_srv: " "Failed to parse authority record! [%d]\n", rrnum)); return NT_STATUS_UNSUCCESSFUL; } } /* Parse the additional records section */ for ( rrnum=0; rrnum<additional_count; rrnum++ ) { struct dns_rr rr; int i; if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len, &p, &rr)) { DEBUG(1,("ads_dns_lookup_srv: Failed " "to parse additional records section! [%d]\n", rrnum)); return NT_STATUS_UNSUCCESSFUL; } /* Only interested in A or AAAA records as a shortcut for having * to come back later and lookup the name. For multi-homed * hosts, the number of additional records and exceed the * number of answer records. */ if (rr.type != T_A || rr.rdatalen != 4) { #if defined(HAVE_IPV6) /* RFC2874 defines A6 records. This * requires recusive and horribly complex lookups. * Bastards. Ignore this for now.... JRA. * Luckily RFC3363 reprecates A6 records. */ if (rr.type != T_AAAA || rr.rdatalen != 16) #endif continue; } for ( i=0; i<idx; i++ ) { if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) { int num_ips = dcs[i].num_ips; struct sockaddr_storage *tmp_ss_s; /* allocate new memory */ if (dcs[i].num_ips == 0) { if ((dcs[i].ss_s = TALLOC_ARRAY(dcs, struct sockaddr_storage, 1 )) == NULL ) { return NT_STATUS_NO_MEMORY; } } else { if ((tmp_ss_s = TALLOC_REALLOC_ARRAY(dcs, dcs[i].ss_s, struct sockaddr_storage, dcs[i].num_ips+1)) == NULL ) { return NT_STATUS_NO_MEMORY; } dcs[i].ss_s = tmp_ss_s; } dcs[i].num_ips++; /* copy the new IP address */ if (rr.type == T_A) { struct in_addr ip; memcpy(&ip, rr.rdata, 4); in_addr_to_sockaddr_storage( &dcs[i].ss_s[num_ips], 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( &dcs[i].ss_s[num_ips], ip6); } #endif } } } TYPESAFE_QSORT(dcs, idx, dnssrvcmp ); *dclist = dcs; *numdcs = idx; return NT_STATUS_OK; } /********************************************************************* Simple wrapper for a DNS NS query *********************************************************************/ NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx, const char *dnsdomain, struct dns_rr_ns **nslist, int *numns) { uint8 *buffer = NULL; int resp_len = 0; struct dns_rr_ns *nsarray = NULL; int query_count, answer_count, auth_count, additional_count; uint8 *p; int rrnum; int idx = 0; NTSTATUS status; if ( !ctx || !dnsdomain || !nslist ) { return NT_STATUS_INVALID_PARAMETER; } /* Send the request. May have to loop several times in case of large replies */ status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len ); if ( !NT_STATUS_IS_OK(status) ) { DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n", nt_errstr(status))); return status; } p = buffer; /* For some insane reason, the ns_initparse() et. al. routines are only available in libresolv.a, and not the shared lib. Who knows why.... So we have to parse the DNS reply ourselves */ /* Pull the answer RR's count from the header. * Use the NMB ordering macros */ query_count = RSVAL( p, 4 ); answer_count = RSVAL( p, 6 ); auth_count = RSVAL( p, 8 ); additional_count = RSVAL( p, 10 ); DEBUG(4,("ads_dns_lookup_ns: " "%d records returned in the answer section.\n", answer_count)); if (answer_count) { if ((nsarray = TALLOC_ARRAY(ctx, struct dns_rr_ns, answer_count)) == NULL ) { DEBUG(0,("ads_dns_lookup_ns: " "talloc() failure for %d char*'s\n", answer_count)); return NT_STATUS_NO_MEMORY; } } else { nsarray = NULL; } /* now skip the header */ p += NS_HFIXEDSZ; /* parse the query section */ for ( rrnum=0; rrnum<query_count; rrnum++ ) { struct dns_query q; if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len, &p, &q)) { DEBUG(1,("ads_dns_lookup_ns: " " Failed to parse query record!\n")); return NT_STATUS_UNSUCCESSFUL; } } /* now we are at the answer section */ for ( rrnum=0; rrnum<answer_count; rrnum++ ) { if (!ads_dns_parse_rr_ns(ctx, buffer, buffer+resp_len, &p, &nsarray[rrnum])) { DEBUG(1,("ads_dns_lookup_ns: " "Failed to parse answer record!\n")); return NT_STATUS_UNSUCCESSFUL; } } idx = rrnum; /* Parse the authority section */ /* just skip these for now */ for ( rrnum=0; rrnum<auth_count; rrnum++ ) { struct dns_rr rr; if ( !ads_dns_parse_rr(ctx, buffer, buffer+resp_len, &p, &rr)) { DEBUG(1,("ads_dns_lookup_ns: " "Failed to parse authority record!\n")); return NT_STATUS_UNSUCCESSFUL; } } /* Parse the additional records section */ for ( rrnum=0; rrnum<additional_count; rrnum++ ) { struct dns_rr rr; int i; if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len, &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; } /******************************************************************** Query with optional sitename. ********************************************************************/ static NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx, const char *servicename, const char *dc_pdc_gc_domains, const char *realm, const char *sitename, struct dns_rr_srv **dclist, int *numdcs ) { char *name; if (sitename) { name = talloc_asprintf(ctx, "%s._tcp.%s._sites.%s._msdcs.%s", servicename, sitename, dc_pdc_gc_domains, realm); } else { name = talloc_asprintf(ctx, "%s._tcp.%s._msdcs.%s", servicename, dc_pdc_gc_domains, realm); } if (!name) { return NT_STATUS_NO_MEMORY; } return ads_dns_lookup_srv( ctx, name, dclist, numdcs ); } /******************************************************************** Query for AD DC's. ********************************************************************/ NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx, const char *realm, const char *sitename, struct dns_rr_srv **dclist, int *numdcs ) { NTSTATUS status; status = ads_dns_query_internal(ctx, "_ldap", "dc", realm, sitename, dclist, numdcs); if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) || NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) { return status; } if (sitename && ((!NT_STATUS_IS_OK(status)) || (NT_STATUS_IS_OK(status) && (numdcs == 0)))) { /* Sitename DNS query may have failed. Try without. */ status = ads_dns_query_internal(ctx, "_ldap", "dc", realm, NULL, dclist, numdcs); } return status; } /******************************************************************** Query for AD GC's. ********************************************************************/ NTSTATUS ads_dns_query_gcs(TALLOC_CTX *ctx, const char *realm, const char *sitename, struct dns_rr_srv **dclist, int *numdcs ) { NTSTATUS status; status = ads_dns_query_internal(ctx, "_ldap", "gc", realm, sitename, dclist, numdcs); if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) || NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) { return status; } if (sitename && ((!NT_STATUS_IS_OK(status)) || (NT_STATUS_IS_OK(status) && (numdcs == 0)))) { /* Sitename DNS query may have failed. Try without. */ status = ads_dns_query_internal(ctx, "_ldap", "gc", realm, NULL, dclist, numdcs); } return status; } /******************************************************************** Query for AD KDC's. Even if our underlying kerberos libraries are UDP only, this is pretty safe as it's unlikely that a KDC supports TCP and not UDP. ********************************************************************/ NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx, const char *dns_forest_name, const char *sitename, struct dns_rr_srv **dclist, int *numdcs ) { NTSTATUS status; status = ads_dns_query_internal(ctx, "_kerberos", "dc", dns_forest_name, sitename, dclist, numdcs); if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) || NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) { return status; } if (sitename && ((!NT_STATUS_IS_OK(status)) || (NT_STATUS_IS_OK(status) && (numdcs == 0)))) { /* Sitename DNS query may have failed. Try without. */ status = ads_dns_query_internal(ctx, "_kerberos", "dc", dns_forest_name, NULL, dclist, numdcs); } return status; } /******************************************************************** Query for AD PDC. Sitename is obsolete here. ********************************************************************/ NTSTATUS ads_dns_query_pdc(TALLOC_CTX *ctx, const char *dns_domain_name, struct dns_rr_srv **dclist, int *numdcs ) { return ads_dns_query_internal(ctx, "_ldap", "pdc", dns_domain_name, NULL, dclist, numdcs); } /******************************************************************** Query for AD DC by guid. Sitename is obsolete here. ********************************************************************/ NTSTATUS ads_dns_query_dcs_guid(TALLOC_CTX *ctx, const char *dns_forest_name, const struct GUID *domain_guid, struct dns_rr_srv **dclist, int *numdcs ) { /*_ldap._tcp.DomainGuid.domains._msdcs.DnsForestName */ const char *domains; char *guid_string; guid_string = GUID_string(ctx, domain_guid); if (!guid_string) { return NT_STATUS_NO_MEMORY; } /* little hack */ domains = talloc_asprintf(ctx, "%s.domains", guid_string); if (!domains) { return NT_STATUS_NO_MEMORY; } TALLOC_FREE(guid_string); return ads_dns_query_internal(ctx, "_ldap", domains, dns_forest_name, NULL, dclist, numdcs); }