s3: Add msg_channel

This is a tevent_based variant of messaging_register

1 files changed, 369 insertions, 0 deletions

diff --git a/source3/lib/msg_channel.c b/source3/lib/msg_channel.c
new file mode 100644
index 0000000000..9a174c0ed6
--- /dev/null
+++ b/source3/lib/msg_channel.c
@@ -0,0 +1,369 @@
+/*
+   Unix SMB/CIFS implementation.
+   Samba3 message channels
+   Copyright (C) Volker Lendecke 2012
+
+   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 "msg_channel.h"
+#include "ctdb_conn.h"
+#include "lib/util/tevent_unix.h"
+
+struct msg_channel {
+	struct ctdb_msg_channel *ctdb_channel;
+	struct messaging_context *msg;
+	uint32_t msg_type;
+
+	struct tevent_req *pending_req;
+	struct tevent_context *ev;
+
+	struct messaging_rec **msgs;
+};
+
+struct msg_channel_init_state {
+	struct msg_channel *channel;
+};
+
+static void msg_channel_init_got_ctdb(struct tevent_req *subreq);
+static void msg_channel_init_got_msg(struct messaging_context *msg,
+			       void *priv, uint32_t msg_type,
+			       struct server_id server_id, DATA_BLOB *data);
+static void msg_channel_trigger(struct tevent_context *ev,
+				struct tevent_immediate *im,
+				void *priv);
+static int msg_channel_init_destructor(struct msg_channel *s);
+
+struct tevent_req *msg_channel_init_send(TALLOC_CTX *mem_ctx,
+				    struct tevent_context *ev,
+				    struct messaging_context *msg,
+				    uint32_t msg_type)
+{
+	struct tevent_req *req, *subreq;
+	struct msg_channel_init_state *state;
+	struct server_id pid;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct msg_channel_init_state);
+	if (req == NULL) {
+		return NULL;
+	}
+
+	state->channel = talloc_zero(state, struct msg_channel);
+	if (tevent_req_nomem(state->channel, req)) {
+		return tevent_req_post(req, ev);
+	}
+	state->channel->msg = msg;
+	state->channel->msg_type = msg_type;
+
+	pid = messaging_server_id(msg);
+	subreq = ctdb_msg_channel_init_send(state, ev, lp_ctdbd_socket(),
+					    pid.pid);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, msg_channel_init_got_ctdb, req);
+	return req;
+}
+
+static void msg_channel_init_got_ctdb(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct msg_channel_init_state *state = tevent_req_data(
+		req, struct msg_channel_init_state);
+	struct msg_channel *s = state->channel;
+	NTSTATUS status;
+	int ret;
+
+	ret = ctdb_msg_channel_init_recv(subreq, s, &s->ctdb_channel);
+	TALLOC_FREE(subreq);
+
+	if (ret == ENOSYS) {
+		s->ctdb_channel = NULL;
+		ret = 0;
+	}
+
+	if (tevent_req_error(req, ret)) {
+		return;
+	}
+	status = messaging_register(s->msg, s, s->msg_type,
+				    msg_channel_init_got_msg);
+	if (!NT_STATUS_IS_OK(status)) {
+		tevent_req_error(req, map_errno_from_nt_status(status));
+		return;
+	}
+	talloc_set_destructor(s, msg_channel_init_destructor);
+	tevent_req_done(req);
+}
+
+static int msg_channel_init_destructor(struct msg_channel *s)
+{
+	messaging_deregister(s->msg, s->msg_type, s);
+	return 0;
+}
+
+int msg_channel_init_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
+			  struct msg_channel **pchannel)
+{
+	struct msg_channel_init_state *state = tevent_req_data(
+		req, struct msg_channel_init_state);
+	int err;
+
+	if (tevent_req_is_unix_error(req, &err)) {
+		return err;
+	}
+	*pchannel = talloc_move(mem_ctx, &state->channel);
+	return 0;
+}
+
+int msg_channel_init(TALLOC_CTX *mem_ctx, struct messaging_context *msg,
+		     uint32_t msgtype, struct msg_channel **pchannel)
+{
+	TALLOC_CTX *frame = talloc_stackframe();
+	struct tevent_context *ev;
+	struct tevent_req *req;
+	int err = ENOMEM;
+	bool ok;
+
+	ev = tevent_context_init(frame);
+	if (ev == NULL) {
+		goto fail;
+	}
+	req = msg_channel_init_send(frame, ev, msg, msgtype);
+	if (req == NULL) {
+		goto fail;
+	}
+	ok = tevent_req_poll(req, ev);
+	if (!ok) {
+		err = errno;
+		goto fail;
+	}
+	err = msg_channel_init_recv(req, mem_ctx, pchannel);
+fail:
+	TALLOC_FREE(frame);
+	return err;
+}
+
+static void msg_channel_init_got_msg(struct messaging_context *msg,
+				     void *priv, uint32_t msg_type,
+				     struct server_id server_id,
+				     DATA_BLOB *data)
+{
+	struct msg_channel *s = talloc_get_type_abort(
+		priv, struct msg_channel);
+	struct messaging_rec *rec;
+	struct messaging_rec **msgs;
+	size_t num_msgs;
+	struct tevent_immediate *im;
+
+	rec = talloc(s, struct messaging_rec);
+	if (rec == NULL) {
+		goto fail;
+	}
+	rec->msg_version = 1;
+	rec->msg_type = msg_type;
+	rec->dest = server_id;
+	rec->src = messaging_server_id(msg);
+	rec->buf.data = (uint8_t *)talloc_memdup(rec, data->data,
+						 data->length);
+	if (rec->buf.data == NULL) {
+		goto fail;
+	}
+	rec->buf.length = data->length;
+
+	num_msgs = talloc_array_length(s->msgs);
+	msgs = talloc_realloc(s, s->msgs, struct messaging_rec *, num_msgs+1);
+	if (msgs == NULL) {
+		goto fail;
+	}
+	s->msgs = msgs;
+	s->msgs[num_msgs] = talloc_move(s->msgs, &rec);
+
+	if (s->pending_req == NULL) {
+		return;
+	}
+
+	im = tevent_create_immediate(s->ev);
+	if (im == NULL) {
+		goto fail;
+	}
+	tevent_schedule_immediate(im, s->ev, msg_channel_trigger, s);
+	return;
+fail:
+	TALLOC_FREE(rec);
+}
+
+struct msg_read_state {
+	struct tevent_context *ev;
+	struct tevent_req *req;
+	struct msg_channel *channel;
+	struct messaging_rec *rec;
+};
+
+static int msg_read_state_destructor(struct msg_read_state *s);
+static void msg_read_got_ctdb(struct tevent_req *subreq);
+
+struct tevent_req *msg_read_send(TALLOC_CTX *mem_ctx,
+				 struct tevent_context *ev,
+				 struct msg_channel *channel)
+{
+	struct tevent_req *req;
+	struct tevent_immediate *im;
+	struct msg_read_state *state;
+	void *msg_tdb_event;
+	size_t num_msgs;
+
+	req = tevent_req_create(mem_ctx, &state, struct msg_read_state);
+	if (req == NULL) {
+		return NULL;
+	}
+	state->ev = ev;
+	state->req = req;
+	state->channel = channel;
+
+	if (channel->pending_req != NULL) {
+		tevent_req_error(req, EBUSY);
+		return tevent_req_post(req, ev);
+	}
+	channel->pending_req = req;
+	channel->ev = ev;
+	talloc_set_destructor(state, msg_read_state_destructor);
+
+	num_msgs = talloc_array_length(channel->msgs);
+	if (num_msgs != 0) {
+		im = tevent_create_immediate(channel->ev);
+		if (tevent_req_nomem(im, req)) {
+			return tevent_req_post(req, ev);
+		}
+		tevent_schedule_immediate(im, channel->ev, msg_channel_trigger,
+					  channel);
+		return req;
+	}
+
+	msg_tdb_event = messaging_tdb_event(state, channel->msg, ev);
+	if (tevent_req_nomem(msg_tdb_event, req)) {
+		return tevent_req_post(req, ev);
+
+	}
+	if (channel->ctdb_channel != NULL) {
+		struct tevent_req *subreq;
+
+		subreq = ctdb_msg_read_send(state, ev,
+					    channel->ctdb_channel);
+		if (tevent_req_nomem(subreq, req)) {
+			return tevent_req_post(req, ev);
+		}
+		tevent_req_set_callback(subreq, msg_read_got_ctdb, req);
+	}
+	return req;
+}
+
+static int msg_read_state_destructor(struct msg_read_state *s)
+{
+	assert(s->channel->pending_req == s->req);
+	s->channel->pending_req = NULL;
+	return 0;
+}
+
+static void msg_channel_trigger(struct tevent_context *ev,
+			       struct tevent_immediate *im,
+			       void *priv)
+{
+	struct msg_channel *channel;
+	struct tevent_req *req;
+	struct msg_read_state *state;
+	size_t num_msgs;
+
+	channel = talloc_get_type_abort(priv, struct msg_channel);
+	req = channel->pending_req;
+	state = tevent_req_data(req, struct msg_read_state);
+
+	talloc_set_destructor(state, NULL);
+	msg_read_state_destructor(state);
+
+	num_msgs = talloc_array_length(channel->msgs);
+	assert(num_msgs > 0);
+
+	state->rec = talloc_move(state, &channel->msgs[0]);
+
+	memmove(channel->msgs, channel->msgs+1,
+		sizeof(struct messaging_rec) * (num_msgs-1));
+	channel->msgs = talloc_realloc(
+		channel, channel->msgs, struct messaging_rec *, num_msgs - 1);
+
+	tevent_req_done(req);
+}
+
+static void msg_read_got_ctdb(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct msg_read_state *state = tevent_req_data(
+		req, struct msg_read_state);
+	DATA_BLOB blob;
+	enum ndr_err_code ndr_err;
+	int ret;
+
+	ret = ctdb_msg_read_recv(subreq, talloc_tos(),
+				 &blob.data, &blob.length);
+	TALLOC_FREE(subreq);
+	if (tevent_req_error(req, ret)) {
+		return;
+	}
+
+	state->rec = talloc(state, struct messaging_rec);
+	if (tevent_req_nomem(state->rec, req)) {
+		return;
+	}
+
+	ndr_err = ndr_push_struct_blob(
+		&blob, state->rec, state->rec,
+		(ndr_push_flags_fn_t)ndr_push_messaging_rec);
+
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		DEBUG(0, ("ndr_push_struct_blob failed: %s\n",
+			  ndr_errstr(ndr_err)));
+		tevent_req_error(req, ndr_map_error2errno(ndr_err));
+		return;
+	}
+	if (state->rec->msg_type == state->channel->msg_type) {
+		tevent_req_done(req);
+		return;
+	}
+	/*
+	 * Got some unexpected msg type, wait for the next one
+	 */
+	subreq = ctdb_msg_read_send(state, state->ev,
+				    state->channel->ctdb_channel);
+	if (tevent_req_nomem(subreq, req)) {
+		return;
+	}
+	tevent_req_set_callback(subreq, msg_read_got_ctdb, req);
+}
+
+int msg_read_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
+		  struct messaging_rec **prec)
+{
+	struct msg_read_state *state = tevent_req_data(
+		req, struct msg_read_state);
+	int err;
+
+	if (tevent_req_is_unix_error(req, &err)) {
+		return err;
+	}
+	*prec = talloc_move(mem_ctx, &state->rec);
+	return 0;
+}