r18006: Actually a smaller change than it looks. Leverage

the get_dc_list code to get the _kerberos. names
for site support. This way we don't depend on one
KDC to do ticket refresh. Even though we know it's
up when we add it, it may go down when we're trying
to refresh.
Jeremy.
(This used to be commit 77fe2a3d7418012a8dbfb6aaeb2a8dd57c6e1a5d)

5 files changed, 155 insertions, 17 deletions

diff --git a/source3/include/smb.h b/source3/include/smb.h
index c5115a551f..5a9d0f7d15 100644
--- a/source3/include/smb.h
+++ b/source3/include/smb.h
@@ -1789,6 +1789,9 @@ struct ip_service {
 	unsigned port;
 };
 
+/* Special name type used to cause a _kerberos DNS lookup. */
+#define KDC_NAME_TYPE 0xDCDC
+
 /* Used by the SMB signing functions. */
 
 typedef struct smb_sign_info {
diff --git a/source3/libads/dns.c b/source3/libads/dns.c
index 579296ea1f..d5c851d5ca 100644
--- a/source3/libads/dns.c
+++ b/source3/libads/dns.c
@@ -649,18 +649,20 @@ BOOL stored_sitename_changed(const char *sitename)
  Query with optional sitename.
 ********************************************************************/
 
-NTSTATUS ads_dns_query_dcs_internal(TALLOC_CTX *ctx,
-				const char *domain,
+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, "_ldap._tcp.%s._sites.dc._msdcs.%s",
-				sitename, domain );
+		name = talloc_asprintf(ctx, "%s._tcp.%s._sites.dc._msdcs.%s",
+				servicename, sitename, realm );
 	} else {
-		name = talloc_asprintf(ctx, "_ldap._tcp.dc._msdcs.%s", domain );
+		name = talloc_asprintf(ctx, "%s._tcp.dc._msdcs.%s",
+				servicename, realm );
 	}
 	if (!name) {
 		return NT_STATUS_NO_MEMORY;
@@ -673,17 +675,44 @@ NTSTATUS ads_dns_query_dcs_internal(TALLOC_CTX *ctx,
 ********************************************************************/
 
 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
-			const char *domain,
+			const char *realm,
 			struct dns_rr_srv **dclist,
 			int *numdcs )
 {
 	NTSTATUS status;
 	char *sitename = sitename_fetch();
 
-	status = ads_dns_query_dcs_internal(ctx, domain, sitename, dclist, numdcs);
+	status = ads_dns_query_internal(ctx, "_ldap", realm, sitename,
+					dclist, numdcs);
 	if (sitename && !NT_STATUS_IS_OK(status)) {
 		/* Sitename DNS query may have failed. Try without. */
-		status = ads_dns_query_dcs_internal(ctx, domain, NULL, dclist, numdcs);
+		status = ads_dns_query_internal(ctx, "_ldap", realm, NULL,
+						dclist, numdcs);
+	}
+	SAFE_FREE(sitename);
+	return status;
+}
+
+/********************************************************************
+ Query for AD KDC's. Transparently use sitename.
+ 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,
+			struct dns_rr_srv **dclist,
+			int *numdcs )
+{
+	NTSTATUS status;
+	char *sitename = sitename_fetch();
+
+	status = ads_dns_query_internal(ctx, "_kerberos", realm, sitename,
+					dclist, numdcs);
+	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);
 	}
 	SAFE_FREE(sitename);
 	return status;
diff --git a/source3/libads/kerberos.c b/source3/libads/kerberos.c
index 4801aec23e..c872508fe8 100644
--- a/source3/libads/kerberos.c
+++ b/source3/libads/kerberos.c
@@ -465,6 +465,46 @@ int kerberos_kinit_password(const char *principal,
 }
 
 /************************************************************************
+ Create a string list of available kdc's, possibly searching by sitename.
+ Does DNS queries.
+************************************************************************/
+
+static char *get_kdc_ip_string(char *mem_ctx, const char *realm, struct in_addr primary_ip)
+{
+	struct ip_service *ip_srv;
+	int count, i;
+	char *kdc_str = talloc_asprintf(mem_ctx, "\tkdc = %s\n",
+					inet_ntoa(primary_ip));
+
+	if (kdc_str == NULL) {
+		return NULL;
+	}
+
+	if (!NT_STATUS_IS_OK(get_kdc_list(realm, &ip_srv, &count))) {
+		DEBUG(10,("get_kdc_ip_string: get_kdc_list failed. Returning %s\n",
+			kdc_str ));
+		return kdc_str;
+	}
+
+	for (i = 0; i < count; i++) {
+		if (ip_equal(ip_srv[i].ip, primary_ip)) {
+			continue;
+		}
+		/* Append to the string - inefficient but not done often. */
+		kdc_str = talloc_asprintf(mem_ctx, "%s\tkdc = %s\n",
+			kdc_str, inet_ntoa(ip_srv[i].ip));
+		if (!kdc_str) {
+			return NULL;
+		}
+	}
+
+	DEBUG(10,("get_kdc_ip_string: Returning %s\n",
+		kdc_str ));
+
+	return kdc_str;
+}
+
+/************************************************************************
  Create  a specific krb5.conf file in the private directory pointing
  at a specific kdc for a realm. Keyed off domain name. Sets
  KRB5_CONFIG environment variable to point to this file. Must be
@@ -477,6 +517,7 @@ BOOL create_local_private_krb5_conf_for_domain(const char *realm, const char *do
 	char *dname = talloc_asprintf(NULL, "%s/smb_krb5", lp_lockdir());
 	char *fname = NULL;
 	char *file_contents = NULL;
+	char *kdc_ip_string;
 	size_t flen = 0;
 	size_t ret;
 	char *realm_upper = NULL;
@@ -505,10 +546,16 @@ BOOL create_local_private_krb5_conf_for_domain(const char *realm, const char *do
 	realm_upper = talloc_strdup(fname, realm);
 	strupper_m(realm_upper);
 
+	kdc_ip_string = get_kdc_ip_string(dname, realm, ip);
+	if (!kdc_ip_string) {
+		TALLOC_FREE(dname);
+		return False;
+	}
+		
 	file_contents = talloc_asprintf(fname, "[libdefaults]\n\tdefault_realm = %s\n\n"
 				"[realms]\n\t%s = {\n"
-				"\t\tkdc = %s\n\t}\n",
-				realm_upper, realm_upper, inet_ntoa(ip));
+				"\t\t%s\t}\n",
+				realm_upper, realm_upper, kdc_ip_string);
 
 	if (!file_contents) {
 		TALLOC_FREE(dname);
diff --git a/source3/libsmb/namecache.c b/source3/libsmb/namecache.c
index ec8a1900d8..afbd807198 100644
--- a/source3/libsmb/namecache.c
+++ b/source3/libsmb/namecache.c
@@ -126,6 +126,10 @@ BOOL namecache_store(const char *name, int name_type,
 	 */
 	if (!gencache_init()) return False;
 
+	if (name_type > 255) {
+		return False; /* Don't store non-real name types. */
+	}
+
 	if ( DEBUGLEVEL >= 5 ) {
 		DEBUG(5, ("namecache_store: storing %d address%s for %s#%02x: ",
 			num_names, num_names == 1 ? "": "es", name, name_type));
@@ -184,6 +188,10 @@ BOOL namecache_fetch(const char *name, int name_type, struct ip_service **ip_lis
 	if (!gencache_init())
 		return False;
 
+	if (name_type > 255) {
+		return False; /* Don't fetch non-real name types. */
+	}
+
 	*num_names = 0;
 
 	/* 
diff --git a/source3/libsmb/namequery.c b/source3/libsmb/namequery.c
index 4c361a3716..af3ac319cc 100644
--- a/source3/libsmb/namequery.c
+++ b/source3/libsmb/namequery.c
@@ -1030,7 +1030,7 @@ static BOOL resolve_ads(const char *name, int name_type,
 	int			numdcs = 0;
 	int			numaddrs = 0;
 
-	if ( name_type != 0x1c )
+	if ((name_type != 0x1c) && (name_type != KDC_NAME_TYPE))
 		return False;
 		
 	DEBUG(5,("resolve_hosts: Attempting to resolve DC's for %s using DNS\n",
@@ -1040,8 +1040,12 @@ static BOOL resolve_ads(const char *name, int name_type,
 		DEBUG(0,("resolve_ads: talloc_init() failed!\n"));
 		return False;
 	}
-		
-	status = ads_dns_query_dcs( ctx, name, &dcs, &numdcs );
+
+	if (name_type == KDC_NAME_TYPE) {
+		status = ads_dns_query_kdcs(ctx, name, &dcs, &numdcs);
+	} else {
+		status = ads_dns_query_dcs(ctx, name, &dcs, &numdcs);
+	}
 	if ( !NT_STATUS_IS_OK( status ) ) {
 		talloc_destroy(ctx);
 		return False;
@@ -1188,6 +1192,13 @@ BOOL internal_resolve_name(const char *name, int name_type,
 				result = True;
 				goto done;
 			}
+		} else if(strequal( tok, "kdc")) {
+			/* deal with KDC_NAME_TYPE names here.  This will result in a
+				SRV record lookup */
+			if (resolve_ads(name, KDC_NAME_TYPE, return_iplist, return_count)) {
+				result = True;
+				goto done;
+			}
 		} else if(strequal( tok, "ads")) {
 			/* deal with 0x1c names here.  This will result in a
 				SRV record lookup */
@@ -1355,13 +1366,17 @@ BOOL get_pdc_ip(const char *domain, struct in_addr *ip)
 	return True;
 }
 
+/* Private enum type for lookups. */
+
+enum dc_lookup_type { DC_NORMAL_LOOKUP, DC_ADS_ONLY, DC_KDC_ONLY };
+
 /********************************************************
  Get the IP address list of the domain controllers for
  a domain.
 *********************************************************/
 
 static NTSTATUS get_dc_list(const char *domain, struct ip_service **ip_list, 
-                            int *count, BOOL ads_only, int *ordered)
+                            int *count, enum dc_lookup_type lookup_type, int *ordered)
 {
 	fstring resolve_order;
 	char *saf_servername;
@@ -1387,7 +1402,7 @@ static NTSTATUS get_dc_list(const char *domain, struct ip_service **ip_list,
 
 	fstrcpy( resolve_order, lp_name_resolve_order() );
 	strlower_m( resolve_order );
-	if ( ads_only )  {
+	if ( lookup_type == DC_ADS_ONLY)  {
 		if ( strstr( resolve_order, "host" ) ) {
 			fstrcpy( resolve_order, "ads" );
 
@@ -1397,6 +1412,11 @@ static NTSTATUS get_dc_list(const char *domain, struct ip_service **ip_list,
 		} else {
                         fstrcpy( resolve_order, "NULL" );
 		}
+	} else if (lookup_type == DC_KDC_ONLY) {
+		/* DNS SRV lookups used by the ads/kdc resolver
+		   are already sorted by priority and weight */
+		*ordered = True;
+		fstrcpy( resolve_order, "kdc" );
 	}
 
 	/* fetch the server we have affinity for.  Add the 
@@ -1558,11 +1578,16 @@ NTSTATUS get_sorted_dc_list( const char *domain, struct ip_service **ip_list, in
 {
 	BOOL ordered;
 	NTSTATUS status;
-	
+	enum dc_lookup_type lookup_type = DC_NORMAL_LOOKUP;
+
 	DEBUG(8,("get_sorted_dc_list: attempting lookup using [%s]\n",
 		(ads_only ? "ads" : lp_name_resolve_order())));
 	
-	status = get_dc_list(domain, ip_list, count, ads_only, &ordered);
+	if (ads_only) {
+		lookup_type = DC_ADS_ONLY;
+	}
+
+	status = get_dc_list(domain, ip_list, count, lookup_type, &ordered);
 	if (!NT_STATUS_IS_OK(status)) {
 		return status; 
 	}
@@ -1574,3 +1599,29 @@ NTSTATUS get_sorted_dc_list( const char *domain, struct ip_service **ip_list, in
 		
 	return NT_STATUS_OK;
 }
+
+/*********************************************************************
+ Get the KDC list - re-use all the logic in get_dc_list.
+*********************************************************************/
+
+NTSTATUS get_kdc_list( const char *realm, struct ip_service **ip_list, int *count)
+{
+	BOOL ordered;
+	NTSTATUS status;
+
+	*count = 0;
+	*ip_list = NULL;
+
+	status = get_dc_list(realm, ip_list, count, DC_KDC_ONLY, &ordered);
+
+	if (!NT_STATUS_IS_OK(status)) {
+		return status; 
+	}
+
+	/* only sort if we don't already have an ordered list */
+	if ( !ordered ) {
+		sort_ip_list2( *ip_list, *count );
+	}
+
+	return NT_STATUS_OK;
+}