s3:winbind: Add a lower-cost alternative to wbinfo -t: wbinfo --ping-dc

This just does a NULL RPC call through an existing NETLOGON connection. If
someone knows an operation that "just works" and does not return NOT_SUPPORTED,
please tell me :-)

13 files changed, 442 insertions, 5 deletions

diff --git a/source3/Makefile.in b/source3/Makefile.in
index 071cb8cf94..59ffa24e27 100644
--- a/source3/Makefile.in
+++ b/source3/Makefile.in
@@ -1225,6 +1225,7 @@ WINBINDD_OBJ1 = \
 		winbindd/winbindd_list_groups.o \
 		winbindd/winbindd_check_machine_acct.o \
 		winbindd/winbindd_change_machine_acct.o \
+		winbindd/winbindd_ping_dc.o \
 		winbindd/winbindd_set_mapping.o \
 		winbindd/winbindd_remove_mapping.o \
 		winbindd/winbindd_set_hwm.o \
diff --git a/source3/librpc/gen_ndr/cli_wbint.c b/source3/librpc/gen_ndr/cli_wbint.c
index 3115a20d9d..592b27b50d 100644
--- a/source3/librpc/gen_ndr/cli_wbint.c
+++ b/source3/librpc/gen_ndr/cli_wbint.c
@@ -2901,6 +2901,136 @@ NTSTATUS rpccli_wbint_ChangeMachineAccount(struct rpc_pipe_client *cli,
 	return r.out.result;
 }
 
+struct rpccli_wbint_PingDc_state {
+	struct wbint_PingDc orig;
+	struct wbint_PingDc tmp;
+	TALLOC_CTX *out_mem_ctx;
+	NTSTATUS (*dispatch_recv)(struct tevent_req *req, TALLOC_CTX *mem_ctx);
+};
+
+static void rpccli_wbint_PingDc_done(struct tevent_req *subreq);
+
+struct tevent_req *rpccli_wbint_PingDc_send(TALLOC_CTX *mem_ctx,
+					    struct tevent_context *ev,
+					    struct rpc_pipe_client *cli)
+{
+	struct tevent_req *req;
+	struct rpccli_wbint_PingDc_state *state;
+	struct tevent_req *subreq;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct rpccli_wbint_PingDc_state);
+	if (req == NULL) {
+		return NULL;
+	}
+	state->out_mem_ctx = NULL;
+	state->dispatch_recv = cli->dispatch_recv;
+
+	/* In parameters */
+
+	/* Out parameters */
+
+	/* Result */
+	ZERO_STRUCT(state->orig.out.result);
+
+	/* make a temporary copy, that we pass to the dispatch function */
+	state->tmp = state->orig;
+
+	subreq = cli->dispatch_send(state, ev, cli,
+				    &ndr_table_wbint,
+				    NDR_WBINT_PINGDC,
+				    &state->tmp);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, rpccli_wbint_PingDc_done, req);
+	return req;
+}
+
+static void rpccli_wbint_PingDc_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct rpccli_wbint_PingDc_state *state = tevent_req_data(
+		req, struct rpccli_wbint_PingDc_state);
+	NTSTATUS status;
+	TALLOC_CTX *mem_ctx;
+
+	if (state->out_mem_ctx) {
+		mem_ctx = state->out_mem_ctx;
+	} else {
+		mem_ctx = state;
+	}
+
+	status = state->dispatch_recv(subreq, mem_ctx);
+	TALLOC_FREE(subreq);
+	if (!NT_STATUS_IS_OK(status)) {
+		tevent_req_nterror(req, status);
+		return;
+	}
+
+	/* Copy out parameters */
+
+	/* Copy result */
+	state->orig.out.result = state->tmp.out.result;
+
+	/* Reset temporary structure */
+	ZERO_STRUCT(state->tmp);
+
+	tevent_req_done(req);
+}
+
+NTSTATUS rpccli_wbint_PingDc_recv(struct tevent_req *req,
+				  TALLOC_CTX *mem_ctx,
+				  NTSTATUS *result)
+{
+	struct rpccli_wbint_PingDc_state *state = tevent_req_data(
+		req, struct rpccli_wbint_PingDc_state);
+	NTSTATUS status;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		tevent_req_received(req);
+		return status;
+	}
+
+	/* Steal possbile out parameters to the callers context */
+	talloc_steal(mem_ctx, state->out_mem_ctx);
+
+	/* Return result */
+	*result = state->orig.out.result;
+
+	tevent_req_received(req);
+	return NT_STATUS_OK;
+}
+
+NTSTATUS rpccli_wbint_PingDc(struct rpc_pipe_client *cli,
+			     TALLOC_CTX *mem_ctx)
+{
+	struct wbint_PingDc r;
+	NTSTATUS status;
+
+	/* In parameters */
+
+	status = cli->dispatch(cli,
+				mem_ctx,
+				&ndr_table_wbint,
+				NDR_WBINT_PINGDC,
+				&r);
+
+	if (!NT_STATUS_IS_OK(status)) {
+		return status;
+	}
+
+	if (NT_STATUS_IS_ERR(status)) {
+		return status;
+	}
+
+	/* Return variables */
+
+	/* Return result */
+	return r.out.result;
+}
+
 struct rpccli_wbint_SetMapping_state {
 	struct wbint_SetMapping orig;
 	struct wbint_SetMapping tmp;
diff --git a/source3/librpc/gen_ndr/cli_wbint.h b/source3/librpc/gen_ndr/cli_wbint.h
index b08ef3fef1..4528d43efc 100644
--- a/source3/librpc/gen_ndr/cli_wbint.h
+++ b/source3/librpc/gen_ndr/cli_wbint.h
@@ -248,6 +248,14 @@ NTSTATUS rpccli_wbint_ChangeMachineAccount_recv(struct tevent_req *req,
 						NTSTATUS *result);
 NTSTATUS rpccli_wbint_ChangeMachineAccount(struct rpc_pipe_client *cli,
 					   TALLOC_CTX *mem_ctx);
+struct tevent_req *rpccli_wbint_PingDc_send(TALLOC_CTX *mem_ctx,
+					    struct tevent_context *ev,
+					    struct rpc_pipe_client *cli);
+NTSTATUS rpccli_wbint_PingDc_recv(struct tevent_req *req,
+				  TALLOC_CTX *mem_ctx,
+				  NTSTATUS *result);
+NTSTATUS rpccli_wbint_PingDc(struct rpc_pipe_client *cli,
+			     TALLOC_CTX *mem_ctx);
 struct tevent_req *rpccli_wbint_SetMapping_send(TALLOC_CTX *mem_ctx,
 						struct tevent_context *ev,
 						struct rpc_pipe_client *cli,
diff --git a/source3/librpc/gen_ndr/ndr_wbint.c b/source3/librpc/gen_ndr/ndr_wbint.c
index 97b29761ee..50f781cc20 100644
--- a/source3/librpc/gen_ndr/ndr_wbint.c
+++ b/source3/librpc/gen_ndr/ndr_wbint.c
@@ -2232,6 +2232,47 @@ _PUBLIC_ void ndr_print_wbint_ChangeMachineAccount(struct ndr_print *ndr, const
 	ndr->depth--;
 }
 
+static enum ndr_err_code ndr_push_wbint_PingDc(struct ndr_push *ndr, int flags, const struct wbint_PingDc *r)
+{
+	if (flags & NDR_IN) {
+	}
+	if (flags & NDR_OUT) {
+		NDR_CHECK(ndr_push_NTSTATUS(ndr, NDR_SCALARS, r->out.result));
+	}
+	return NDR_ERR_SUCCESS;
+}
+
+static enum ndr_err_code ndr_pull_wbint_PingDc(struct ndr_pull *ndr, int flags, struct wbint_PingDc *r)
+{
+	if (flags & NDR_IN) {
+	}
+	if (flags & NDR_OUT) {
+		NDR_CHECK(ndr_pull_NTSTATUS(ndr, NDR_SCALARS, &r->out.result));
+	}
+	return NDR_ERR_SUCCESS;
+}
+
+_PUBLIC_ void ndr_print_wbint_PingDc(struct ndr_print *ndr, const char *name, int flags, const struct wbint_PingDc *r)
+{
+	ndr_print_struct(ndr, name, "wbint_PingDc");
+	ndr->depth++;
+	if (flags & NDR_SET_VALUES) {
+		ndr->flags |= LIBNDR_PRINT_SET_VALUES;
+	}
+	if (flags & NDR_IN) {
+		ndr_print_struct(ndr, "in", "wbint_PingDc");
+		ndr->depth++;
+		ndr->depth--;
+	}
+	if (flags & NDR_OUT) {
+		ndr_print_struct(ndr, "out", "wbint_PingDc");
+		ndr->depth++;
+		ndr_print_NTSTATUS(ndr, "result", r->out.result);
+		ndr->depth--;
+	}
+	ndr->depth--;
+}
+
 static enum ndr_err_code ndr_push_wbint_SetMapping(struct ndr_push *ndr, int flags, const struct wbint_SetMapping *r)
 {
 	if (flags & NDR_IN) {
@@ -2567,6 +2608,14 @@ static const struct ndr_interface_call wbint_calls[] = {
 		false,
 	},
 	{
+		"wbint_PingDc",
+		sizeof(struct wbint_PingDc),
+		(ndr_push_flags_fn_t) ndr_push_wbint_PingDc,
+		(ndr_pull_flags_fn_t) ndr_pull_wbint_PingDc,
+		(ndr_print_function_t) ndr_print_wbint_PingDc,
+		false,
+	},
+	{
 		"wbint_SetMapping",
 		sizeof(struct wbint_SetMapping),
 		(ndr_push_flags_fn_t) ndr_push_wbint_SetMapping,
@@ -2619,7 +2668,7 @@ const struct ndr_interface_table ndr_table_wbint = {
 		NDR_WBINT_VERSION
 	},
 	.helpstring	= NDR_WBINT_HELPSTRING,
-	.num_calls	= 23,
+	.num_calls	= 24,
 	.calls		= wbint_calls,
 	.endpoints	= &wbint_endpoints,
 	.authservices	= &wbint_authservices
diff --git a/source3/librpc/gen_ndr/ndr_wbint.h b/source3/librpc/gen_ndr/ndr_wbint.h
index e163ff3674..4a381ccfb2 100644
--- a/source3/librpc/gen_ndr/ndr_wbint.h
+++ b/source3/librpc/gen_ndr/ndr_wbint.h
@@ -51,13 +51,15 @@ extern const struct ndr_interface_table ndr_table_wbint;
 
 #define NDR_WBINT_CHANGEMACHINEACCOUNT (0x13)
 
-#define NDR_WBINT_SETMAPPING (0x14)
+#define NDR_WBINT_PINGDC (0x14)
 
-#define NDR_WBINT_REMOVEMAPPING (0x15)
+#define NDR_WBINT_SETMAPPING (0x15)
 
-#define NDR_WBINT_SETHWM (0x16)
+#define NDR_WBINT_REMOVEMAPPING (0x16)
 
-#define NDR_WBINT_CALL_COUNT (23)
+#define NDR_WBINT_SETHWM (0x17)
+
+#define NDR_WBINT_CALL_COUNT (24)
 enum ndr_err_code ndr_push_wbint_userinfo(struct ndr_push *ndr, int ndr_flags, const struct wbint_userinfo *r);
 enum ndr_err_code ndr_pull_wbint_userinfo(struct ndr_pull *ndr, int ndr_flags, struct wbint_userinfo *r);
 void ndr_print_wbint_userinfo(struct ndr_print *ndr, const char *name, const struct wbint_userinfo *r);
@@ -99,6 +101,7 @@ void ndr_print_wbint_DsGetDcName(struct ndr_print *ndr, const char *name, int fl
 void ndr_print_wbint_LookupRids(struct ndr_print *ndr, const char *name, int flags, const struct wbint_LookupRids *r);
 void ndr_print_wbint_CheckMachineAccount(struct ndr_print *ndr, const char *name, int flags, const struct wbint_CheckMachineAccount *r);
 void ndr_print_wbint_ChangeMachineAccount(struct ndr_print *ndr, const char *name, int flags, const struct wbint_ChangeMachineAccount *r);
+void ndr_print_wbint_PingDc(struct ndr_print *ndr, const char *name, int flags, const struct wbint_PingDc *r);
 void ndr_print_wbint_SetMapping(struct ndr_print *ndr, const char *name, int flags, const struct wbint_SetMapping *r);
 void ndr_print_wbint_RemoveMapping(struct ndr_print *ndr, const char *name, int flags, const struct wbint_RemoveMapping *r);
 void ndr_print_wbint_SetHWM(struct ndr_print *ndr, const char *name, int flags, const struct wbint_SetHWM *r);
diff --git a/source3/librpc/gen_ndr/srv_wbint.c b/source3/librpc/gen_ndr/srv_wbint.c
index 0f39cd93e1..efd9be6b7a 100644
--- a/source3/librpc/gen_ndr/srv_wbint.c
+++ b/source3/librpc/gen_ndr/srv_wbint.c
@@ -1610,6 +1610,79 @@ static bool api_wbint_ChangeMachineAccount(pipes_struct *p)
 	return true;
 }
 
+static bool api_wbint_PingDc(pipes_struct *p)
+{
+	const struct ndr_interface_call *call;
+	struct ndr_pull *pull;
+	struct ndr_push *push;
+	enum ndr_err_code ndr_err;
+	DATA_BLOB blob;
+	struct wbint_PingDc *r;
+
+	call = &ndr_table_wbint.calls[NDR_WBINT_PINGDC];
+
+	r = talloc(talloc_tos(), struct wbint_PingDc);
+	if (r == NULL) {
+		return false;
+	}
+
+	if (!prs_data_blob(&p->in_data.data, &blob, r)) {
+		talloc_free(r);
+		return false;
+	}
+
+	pull = ndr_pull_init_blob(&blob, r, NULL);
+	if (pull == NULL) {
+		talloc_free(r);
+		return false;
+	}
+
+	pull->flags |= LIBNDR_FLAG_REF_ALLOC;
+	ndr_err = call->ndr_pull(pull, NDR_IN, r);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		talloc_free(r);
+		return false;
+	}
+
+	if (DEBUGLEVEL >= 10) {
+		NDR_PRINT_IN_DEBUG(wbint_PingDc, r);
+	}
+
+	r->out.result = _wbint_PingDc(p, r);
+
+	if (p->rng_fault_state) {
+		talloc_free(r);
+		/* Return true here, srv_pipe_hnd.c will take care */
+		return true;
+	}
+
+	if (DEBUGLEVEL >= 10) {
+		NDR_PRINT_OUT_DEBUG(wbint_PingDc, r);
+	}
+
+	push = ndr_push_init_ctx(r, NULL);
+	if (push == NULL) {
+		talloc_free(r);
+		return false;
+	}
+
+	ndr_err = call->ndr_push(push, NDR_OUT, r);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		talloc_free(r);
+		return false;
+	}
+
+	blob = ndr_push_blob(push);
+	if (!prs_copy_data_in(&p->out_data.rdata, (const char *)blob.data, (uint32_t)blob.length)) {
+		talloc_free(r);
+		return false;
+	}
+
+	talloc_free(r);
+
+	return true;
+}
+
 static bool api_wbint_SetMapping(pipes_struct *p)
 {
 	const struct ndr_interface_call *call;
@@ -1853,6 +1926,7 @@ static struct api_struct api_wbint_cmds[] =
 	{"WBINT_LOOKUPRIDS", NDR_WBINT_LOOKUPRIDS, api_wbint_LookupRids},
 	{"WBINT_CHECKMACHINEACCOUNT", NDR_WBINT_CHECKMACHINEACCOUNT, api_wbint_CheckMachineAccount},
 	{"WBINT_CHANGEMACHINEACCOUNT", NDR_WBINT_CHANGEMACHINEACCOUNT, api_wbint_ChangeMachineAccount},
+	{"WBINT_PINGDC", NDR_WBINT_PINGDC, api_wbint_PingDc},
 	{"WBINT_SETMAPPING", NDR_WBINT_SETMAPPING, api_wbint_SetMapping},
 	{"WBINT_REMOVEMAPPING", NDR_WBINT_REMOVEMAPPING, api_wbint_RemoveMapping},
 	{"WBINT_SETHWM", NDR_WBINT_SETHWM, api_wbint_SetHWM},
@@ -2115,6 +2189,12 @@ NTSTATUS rpc_wbint_dispatch(struct rpc_pipe_client *cli, TALLOC_CTX *mem_ctx, co
 			return NT_STATUS_OK;
 		}
 
+		case NDR_WBINT_PINGDC: {
+			struct wbint_PingDc *r = (struct wbint_PingDc *)_r;
+			r->out.result = _wbint_PingDc(cli->pipes_struct, r);
+			return NT_STATUS_OK;
+		}
+
 		case NDR_WBINT_SETMAPPING: {
 			struct wbint_SetMapping *r = (struct wbint_SetMapping *)_r;
 			r->out.result = _wbint_SetMapping(cli->pipes_struct, r);
diff --git a/source3/librpc/gen_ndr/srv_wbint.h b/source3/librpc/gen_ndr/srv_wbint.h
index c8c04fb3cc..716f1ac9d1 100644
--- a/source3/librpc/gen_ndr/srv_wbint.h
+++ b/source3/librpc/gen_ndr/srv_wbint.h
@@ -21,6 +21,7 @@ NTSTATUS _wbint_DsGetDcName(pipes_struct *p, struct wbint_DsGetDcName *r);
 NTSTATUS _wbint_LookupRids(pipes_struct *p, struct wbint_LookupRids *r);
 NTSTATUS _wbint_CheckMachineAccount(pipes_struct *p, struct wbint_CheckMachineAccount *r);
 NTSTATUS _wbint_ChangeMachineAccount(pipes_struct *p, struct wbint_ChangeMachineAccount *r);
+NTSTATUS _wbint_PingDc(pipes_struct *p, struct wbint_PingDc *r);
 NTSTATUS _wbint_SetMapping(pipes_struct *p, struct wbint_SetMapping *r);
 NTSTATUS _wbint_RemoveMapping(pipes_struct *p, struct wbint_RemoveMapping *r);
 NTSTATUS _wbint_SetHWM(pipes_struct *p, struct wbint_SetHWM *r);
@@ -46,6 +47,7 @@ NTSTATUS _wbint_DsGetDcName(pipes_struct *p, struct wbint_DsGetDcName *r);
 NTSTATUS _wbint_LookupRids(pipes_struct *p, struct wbint_LookupRids *r);
 NTSTATUS _wbint_CheckMachineAccount(pipes_struct *p, struct wbint_CheckMachineAccount *r);
 NTSTATUS _wbint_ChangeMachineAccount(pipes_struct *p, struct wbint_ChangeMachineAccount *r);
+NTSTATUS _wbint_PingDc(pipes_struct *p, struct wbint_PingDc *r);
 NTSTATUS _wbint_SetMapping(pipes_struct *p, struct wbint_SetMapping *r);
 NTSTATUS _wbint_RemoveMapping(pipes_struct *p, struct wbint_RemoveMapping *r);
 NTSTATUS _wbint_SetHWM(pipes_struct *p, struct wbint_SetHWM *r);
diff --git a/source3/librpc/gen_ndr/wbint.h b/source3/librpc/gen_ndr/wbint.h
index 962a87ea26..96b7800624 100644
--- a/source3/librpc/gen_ndr/wbint.h
+++ b/source3/librpc/gen_ndr/wbint.h
@@ -303,6 +303,14 @@ struct wbint_ChangeMachineAccount {
 };
 
 
+struct wbint_PingDc {
+	struct {
+		NTSTATUS result;
+	} out;
+
+};
+
+
 struct wbint_SetMapping {
 	struct {
 		struct dom_sid *sid;/* [ref] */
diff --git a/source3/librpc/idl/wbint.idl b/source3/librpc/idl/wbint.idl
index e44f179723..432d59e086 100644
--- a/source3/librpc/idl/wbint.idl
+++ b/source3/librpc/idl/wbint.idl
@@ -150,6 +150,9 @@ interface wbint
     NTSTATUS wbint_ChangeMachineAccount(
 	);
 
+    NTSTATUS wbint_PingDc(
+	);
+
     typedef [public] enum {
 	WBINT_ID_TYPE_NOT_SPECIFIED,
 	WBINT_ID_TYPE_UID,
diff --git a/source3/winbindd/winbindd.c b/source3/winbindd/winbindd.c
index e09374c5cb..597957d9d6 100644
--- a/source3/winbindd/winbindd.c
+++ b/source3/winbindd/winbindd.c
@@ -532,6 +532,8 @@ static struct winbindd_async_dispatch_table async_nonpriv_table[] = {
 	  winbindd_list_groups_send, winbindd_list_groups_recv },
 	{ WINBINDD_CHECK_MACHACC, "CHECK_MACHACC",
 	  winbindd_check_machine_acct_send, winbindd_check_machine_acct_recv },
+	{ WINBINDD_PING_DC, "PING_DC",
+	  winbindd_ping_dc_send, winbindd_ping_dc_recv },
 
 	{ 0, NULL, NULL, NULL }
 };
diff --git a/source3/winbindd/winbindd_dual_srv.c b/source3/winbindd/winbindd_dual_srv.c
index cecbb61051..b247d5a233 100644
--- a/source3/winbindd/winbindd_dual_srv.c
+++ b/source3/winbindd/winbindd_dual_srv.c
@@ -510,6 +510,54 @@ again:
 	return status;
 }
 
+NTSTATUS _wbint_PingDc(pipes_struct *p, struct wbint_PingDc *r)
+{
+	NTSTATUS status;
+	struct winbindd_domain *domain;
+	struct rpc_pipe_client *netlogon_pipe;
+	union netr_CONTROL_QUERY_INFORMATION info;
+	WERROR werr;
+	fstring logon_server;
+
+	domain = wb_child_domain();
+	if (domain == NULL) {
+		return NT_STATUS_REQUEST_NOT_ACCEPTED;
+	}
+
+	status = cm_connect_netlogon(domain, &netlogon_pipe);
+        if (!NT_STATUS_IS_OK(status)) {
+                DEBUG(3, ("could not open handle to NETLOGON pipe\n"));
+		return status;
+        }
+
+	fstr_sprintf(logon_server, "\\\\%s", domain->dcname);
+
+	/*
+	 * This provokes a WERR_NOT_SUPPORTED error message. This is
+	 * documented in the wspp docs. I could not get a successful
+	 * call to work, but the main point here is testing that the
+	 * netlogon pipe works.
+	 */
+	status = rpccli_netr_LogonControl(netlogon_pipe, p->mem_ctx,
+					  logon_server, NETLOGON_CONTROL_QUERY,
+					  2, &info, &werr);
+
+	if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
+		DEBUG(2, ("rpccli_netr_LogonControl timed out\n"));
+		invalidate_cm_connection(&domain->conn);
+		return status;
+	}
+
+	if (!NT_STATUS_EQUAL(status, NT_STATUS_CTL_FILE_NOT_SUPPORTED)) {
+		DEBUG(2, ("rpccli_netr_LogonControl returned %s, expected "
+			  "NT_STATUS_CTL_FILE_NOT_SUPPORTED\n",
+			  nt_errstr(status)));
+		return status;
+	}
+
+	DEBUG(5, ("winbindd_dual_ping_dc succeeded\n"));
+	return NT_STATUS_OK;
+}
 
 NTSTATUS _wbint_SetMapping(pipes_struct *p, struct wbint_SetMapping *r)
 {
diff --git a/source3/winbindd/winbindd_ping_dc.c b/source3/winbindd/winbindd_ping_dc.c
new file mode 100644
index 0000000000..e06e5896c2
--- /dev/null
+++ b/source3/winbindd/winbindd_ping_dc.c
@@ -0,0 +1,96 @@
+/*
+   Unix SMB/CIFS implementation.
+   async implementation of WINBINDD_PING_DC
+   Copyright (C) Volker Lendecke 2009
+
+   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 "winbindd.h"
+#include "librpc/gen_ndr/cli_wbint.h"
+
+struct winbindd_ping_dc_state {
+	uint8_t dummy;
+};
+
+static void winbindd_ping_dc_done(struct tevent_req *subreq);
+
+struct tevent_req *winbindd_ping_dc_send(TALLOC_CTX *mem_ctx,
+					 struct tevent_context *ev,
+					 struct winbindd_cli_state *cli,
+					 struct winbindd_request *request)
+{
+	struct tevent_req *req, *subreq;
+	struct winbindd_ping_dc_state *state;
+	struct winbindd_domain *domain;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct winbindd_ping_dc_state);
+	if (req == NULL) {
+		return NULL;
+	}
+
+	if (request->domain_name[0] == '\0') {
+		/* preserve old behavior, when no domain name is given */
+		domain = find_our_domain();
+	} else {
+		domain = find_domain_from_name(request->domain_name);
+	}
+	if (domain == NULL) {
+		tevent_req_nterror(req, NT_STATUS_NO_SUCH_DOMAIN);
+		return tevent_req_post(req, ev);
+	}
+	if (domain->internal) {
+		/*
+		 * Internal domains are passdb based, we can always
+		 * contact them.
+		 */
+		tevent_req_done(req);
+		return tevent_req_post(req, ev);
+	}
+
+	subreq = rpccli_wbint_PingDc_send(state, ev, domain->child.rpccli);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, winbindd_ping_dc_done, req);
+	return req;
+}
+
+static void winbindd_ping_dc_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct winbindd_ping_dc_state *state = tevent_req_data(
+		req, struct winbindd_ping_dc_state);
+	NTSTATUS status, result;
+
+	status = rpccli_wbint_PingDc_recv(subreq, state, &result);
+	if (!NT_STATUS_IS_OK(status)) {
+		tevent_req_nterror(req, status);
+		return;
+	}
+	if (!NT_STATUS_IS_OK(result)) {
+		tevent_req_nterror(req, result);
+		return;
+	}
+	tevent_req_done(req);
+}
+
+NTSTATUS winbindd_ping_dc_recv(struct tevent_req *req,
+			       struct winbindd_response *presp)
+{
+	return tevent_req_simple_recv_ntstatus(req);
+}
diff --git a/source3/winbindd/winbindd_proto.h b/source3/winbindd/winbindd_proto.h
index 5a03f5d3b8..fab31ba60b 100644
--- a/source3/winbindd/winbindd_proto.h
+++ b/source3/winbindd/winbindd_proto.h
@@ -848,6 +848,13 @@ struct tevent_req *winbindd_check_machine_acct_send(TALLOC_CTX *mem_ctx,
 NTSTATUS winbindd_check_machine_acct_recv(struct tevent_req *req,
 					  struct winbindd_response *presp);
 
+struct tevent_req *winbindd_ping_dc_send(TALLOC_CTX *mem_ctx,
+					 struct tevent_context *ev,
+					 struct winbindd_cli_state *cli,
+					 struct winbindd_request *request);
+NTSTATUS winbindd_ping_dc_recv(struct tevent_req *req,
+			       struct winbindd_response *presp);
+
 struct tevent_req *winbindd_change_machine_acct_send(TALLOC_CTX *mem_ctx,
 						     struct tevent_context *ev,
 						     struct winbindd_cli_state *cli,