/* Unix SMB/CIFS implementation. DNS utility library Copyright (C) Gerald (Jerry) Carter 2006. 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 2 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, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include "includes.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 # 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; pstring hostname; 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; pstring hostname; 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; pstring dcname; 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 ); 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; pstring nsname; 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 *********************************************************************/ 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; int resp_len = NS_PACKETSZ; do { if ( buffer ) TALLOC_FREE( buffer ); buf_len = resp_len * sizeof(uint8); if ( (buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) { DEBUG(0,("ads_dns_lookup_srv: talloc() failed!\n")); return NT_STATUS_NO_MEMORY; } 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 ); if (errno == ETIMEDOUT) { return NT_STATUS_IO_TIMEOUT; } if (errno == ECONNREFUSED) { return NT_STATUS_CONNECTION_REFUSED; } return NT_STATUS_UNSUCCESSFUL; } } while ( buf_len < resp_len && resp_len < MAX_DNS_PACKET_SIZE ); *buf = buffer; *resp_length = resp_len; return NT_STATUS_OK; } /********************************************************************* 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 ( (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; } /* 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!\n")); 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 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_srv: 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_srv: 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. For multi-homed hosts, the number of additional records and exceed the number of answer records. */ if ( (rr.type != T_A) || (rr.rdatalen != 4) ) continue; for ( i=0; i<idx; i++ ) { if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) { int num_ips = dcs[i].num_ips; uint8 *buf; struct in_addr *tmp_ips; /* allocate new memory */ if ( dcs[i].num_ips == 0 ) { if ( (dcs[i].ips = TALLOC_ARRAY( dcs, struct in_addr, 1 )) == NULL ) { return NT_STATUS_NO_MEMORY; } } else { if ( (tmp_ips = TALLOC_REALLOC_ARRAY( dcs, dcs[i].ips, struct in_addr, dcs[i].num_ips+1)) == NULL ) { return NT_STATUS_NO_MEMORY; } dcs[i].ips = tmp_ips; } dcs[i].num_ips++; /* copy the new IP address */ buf = (uint8*)&dcs[i].ips[num_ips].s_addr; memcpy( buf, rr.rdata, 4 ); } } } qsort( dcs, idx, sizeof(struct dns_rr_srv), QSORT_CAST 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 ( (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; } /* 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) ) continue; for ( i=0; i<idx; i++ ) { if ( strcmp( rr.hostname, nsarray[i].hostname ) == 0 ) { uint8 *buf = (uint8*)&nsarray[i].ip.s_addr; memcpy( buf, rr.rdata, 4 ); } } } *nslist = nsarray; *numns = idx; return NT_STATUS_OK; } /**************************************************************************** Store and fetch the AD client sitename. ****************************************************************************/ #define SITENAME_KEY "AD_SITENAME/DOMAIN/%s" static char *sitename_key(const char *realm) { char *keystr; if (asprintf(&keystr, SITENAME_KEY, strupper_static(realm)) == -1) { return NULL; } return keystr; } /**************************************************************************** Store the AD client sitename. We store indefinately as every new CLDAP query will re-write this. If the sitename is "Default-First-Site-Name" we don't store it as this isn't a valid DNS name. ****************************************************************************/ BOOL sitename_store(const char *realm, const char *sitename) { time_t expire; BOOL ret = False; char *key; if (!gencache_init()) { return False; } if (!realm || (strlen(realm) == 0)) { DEBUG(0,("no realm\n")); return False; } key = sitename_key(realm); if (!sitename || (sitename && !*sitename)) { DEBUG(5,("sitename_store: deleting empty sitename!\n")); ret = gencache_del(key); SAFE_FREE(key); return ret; } expire = get_time_t_max(); /* Store indefinately. */ DEBUG(10,("sitename_store: realm = [%s], sitename = [%s], expire = [%u]\n", realm, sitename, (unsigned int)expire )); ret = gencache_set( key, sitename, expire ); SAFE_FREE(key); return ret; } /**************************************************************************** Fetch the AD client sitename. Caller must free. ****************************************************************************/ char *sitename_fetch(const char *realm) { char *sitename = NULL; time_t timeout; BOOL ret = False; const char *query_realm; char *key; if (!gencache_init()) { return False; } if (!realm || (strlen(realm) == 0)) { query_realm = lp_realm(); } else { query_realm = realm; } key = sitename_key(query_realm); ret = gencache_get( key, &sitename, &timeout ); SAFE_FREE(key); if ( !ret ) { DEBUG(5,("sitename_fetch: No stored sitename for %s\n", query_realm)); } else { DEBUG(5,("sitename_fetch: Returning sitename for %s: \"%s\"\n", query_realm, sitename )); } return sitename; } /**************************************************************************** Did the sitename change ? ****************************************************************************/ BOOL stored_sitename_changed(const char *realm, const char *sitename) { BOOL ret = False; char *new_sitename; if (!realm || (strlen(realm) == 0)) { DEBUG(0,("no realm\n")); return False; } new_sitename = sitename_fetch(realm); if (sitename && new_sitename && !strequal(sitename, new_sitename)) { ret = True; } else if ((sitename && !new_sitename) || (!sitename && new_sitename)) { ret = True; } SAFE_FREE(new_sitename); return ret; } /******************************************************************** Query with optional sitename. ********************************************************************/ NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx, const char *servicename, 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.dc._msdcs.%s", servicename, sitename, realm ); } else { name = talloc_asprintf(ctx, "%s._tcp.dc._msdcs.%s", servicename, 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", 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)) { /* Sitename DNS query may have failed. Try without. */ status = ads_dns_query_internal(ctx, "_ldap", 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 *realm, const char *sitename, struct dns_rr_srv **dclist, int *numdcs ) { NTSTATUS status; status = ads_dns_query_internal(ctx, "_kerberos", 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)) { /* Sitename DNS query may have failed. Try without. */ status = ads_dns_query_internal(ctx, "_kerberos", realm, NULL, dclist, numdcs); } return status; }