Add new async libsmb infrastructure

I know this is just yet another iteration, but I like this one much better than
the one that exists right now :-)

It will do trans and echo requests without a _recv helper and without
unnecessary memcpy().

4 files changed, 807 insertions, 0 deletions

diff --git a/source3/include/async_smb.h b/source3/include/async_smb.h
index 2ac1101a1e..adbfc6e5ca 100644
--- a/source3/include/async_smb.h
+++ b/source3/include/async_smb.h
@@ -151,4 +151,31 @@ NTSTATUS cli_pull_error(char *buf);
 
 void cli_set_error(struct cli_state *cli, NTSTATUS status);
 
+struct tevent_req *cli_smb_req_create(TALLOC_CTX *mem_ctx,
+				      struct event_context *ev,
+				      struct cli_state *cli,
+				      uint8_t smb_command,
+				      uint8_t additional_flags,
+				      uint8_t wct, uint16_t *vwv,
+				      int iov_count,
+				      struct iovec *bytes_iov);
+bool cli_smb_req_send(struct tevent_req *req);
+size_t cli_smb_wct_ofs(struct tevent_req **reqs, int num_reqs);
+bool cli_smb_chain_send(struct tevent_req **reqs, int num_reqs);
+uint8_t *cli_smb_inbuf(struct tevent_req *req);
+bool cli_has_async_calls(struct cli_state *cli);
+void cli_smb_req_unset_pending(struct tevent_req *req);
+bool cli_smb_req_set_pending(struct tevent_req *req);
+uint16_t cli_smb_req_mid(struct tevent_req *req);
+void cli_smb_req_set_mid(struct tevent_req *req, uint16_t mid);
+struct tevent_req *cli_smb_send(TALLOC_CTX *mem_ctx, struct event_context *ev,
+				struct cli_state *cli,
+				uint8_t smb_command, uint8_t additional_flags,
+				uint8_t wct, uint16_t *vwv,
+				uint32_t num_bytes,
+				const uint8_t *bytes);
+NTSTATUS cli_smb_recv(struct tevent_req *req, uint8_t min_wct,
+		      uint8_t *pwct, uint16_t **pvwv,
+		      uint32_t *pnum_bytes, uint8_t **pbytes);
+
 #endif
diff --git a/source3/include/client.h b/source3/include/client.h
index 73a1d7b554..c10d2109d8 100644
--- a/source3/include/client.h
+++ b/source3/include/client.h
@@ -291,6 +291,9 @@ struct cli_state {
 
 	/* Where (if anywhere) this is mounted under DFS. */
 	char *dfs_mountpoint;
+
+	struct tevent_queue *outgoing;
+	struct tevent_req **pending;
 };
 
 typedef struct file_info {
diff --git a/source3/libsmb/async_smb.c b/source3/libsmb/async_smb.c
index 86fd5c8bef..4f88cdbd80 100644
--- a/source3/libsmb/async_smb.c
+++ b/source3/libsmb/async_smb.c
@@ -1133,3 +1133,768 @@ static void cli_state_handler(struct event_context *event_ctx,
 	close(cli->fd);
 	cli->fd = -1;
 }
+
+#define MAX_SMB_IOV 5
+
+struct cli_smb_state {
+	struct tevent_context *ev;
+	struct cli_state *cli;
+	uint8_t header[smb_wct+1]; /* Space for the header including the wct */
+
+	/*
+	 * For normal requests, cli_smb_req_send chooses a mid. Secondary
+	 * trans requests need to use the mid of the primary request, so we
+	 * need a place to store it. Assume it's set if != 0.
+	 */
+	uint16_t mid;
+
+	uint16_t *vwv;
+	uint8_t bytecount_buf[2];
+
+	struct iovec iov[MAX_SMB_IOV+3];
+	int iov_count;
+
+	uint8_t *inbuf;
+	uint32_t seqnum;
+	int chain_num;
+	struct tevent_req **chained_requests;
+};
+
+static uint16_t cli_alloc_mid(struct cli_state *cli)
+{
+	int num_pending = talloc_array_length(cli->pending);
+	uint16_t result;
+
+	while (true) {
+		int i;
+
+		result = cli->mid++;
+		if (result == 0) {
+			continue;
+		}
+
+		for (i=0; i<num_pending; i++) {
+			if (result == cli_smb_req_mid(cli->pending[i])) {
+				break;
+			}
+		}
+
+		if (i == num_pending) {
+			return result;
+		}
+	}
+}
+
+void cli_smb_req_unset_pending(struct tevent_req *req)
+{
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+	struct cli_state *cli = state->cli;
+	int num_pending = talloc_array_length(cli->pending);
+	int i;
+
+	if (num_pending == 1) {
+		/*
+		 * The pending read_smb tevent_req is a child of
+		 * cli->pending. So if nothing is pending anymore, we need to
+		 * delete the socket read fde.
+		 */
+		TALLOC_FREE(cli->pending);
+		return;
+	}
+
+	for (i=0; i<num_pending; i++) {
+		if (req == cli->pending[i]) {
+			break;
+		}
+	}
+	if (i == num_pending) {
+		/*
+		 * Something's seriously broken. Just returning here is the
+		 * right thing nevertheless, the point of this routine is to
+		 * remove ourselves from cli->pending.
+		 */
+		return;
+	}
+
+	/*
+	 * Remove ourselves from the cli->pending array
+	 */
+	if (num_pending > 1) {
+		cli->pending[i] = cli->pending[num_pending-1];
+	}
+
+	/*
+	 * No NULL check here, we're shrinking by sizeof(void *), and
+	 * talloc_realloc just adjusts the size for this.
+	 */
+	cli->pending = talloc_realloc(NULL, cli->pending, struct tevent_req *,
+				      num_pending - 1);
+	return;
+}
+
+static int cli_smb_req_destructor(struct tevent_req *req)
+{
+	cli_smb_req_unset_pending(req);
+	return 0;
+}
+
+static void cli_smb_received(struct tevent_req *subreq);
+
+bool cli_smb_req_set_pending(struct tevent_req *req)
+{
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+	struct cli_state *cli;
+	struct tevent_req **pending;
+	int num_pending;
+	struct tevent_req *subreq;
+
+	cli = state->cli;
+	num_pending = talloc_array_length(cli->pending);
+
+	pending = talloc_realloc(cli, cli->pending, struct tevent_req *,
+				 num_pending+1);
+	if (pending == NULL) {
+		return false;
+	}
+	pending[num_pending] = req;
+	cli->pending = pending;
+	talloc_set_destructor(req, cli_smb_req_destructor);
+
+	if (num_pending > 0) {
+		return true;
+	}
+
+	/*
+	 * We're the first ones, add the read_smb request that waits for the
+	 * answer from the server
+	 */
+	subreq = read_smb_send(cli->pending, state->ev, cli->fd);
+	if (subreq == NULL) {
+		cli_smb_req_unset_pending(req);
+		return false;
+	}
+	tevent_req_set_callback(subreq, cli_smb_received, cli);
+	return true;
+}
+
+/*
+ * Fetch a smb request's mid. Only valid after the request has been sent by
+ * cli_smb_req_send().
+ */
+uint16_t cli_smb_req_mid(struct tevent_req *req)
+{
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+	return SVAL(state->header, smb_mid);
+}
+
+void cli_smb_req_set_mid(struct tevent_req *req, uint16_t mid)
+{
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+	state->mid = mid;
+}
+
+static size_t iov_len(const struct iovec *iov, int count)
+{
+	size_t result = 0;
+	int i;
+	for (i=0; i<count; i++) {
+		result += iov[i].iov_len;
+	}
+	return result;
+}
+
+static uint8_t *iov_concat(TALLOC_CTX *mem_ctx, const struct iovec *iov,
+			   int count)
+{
+	size_t len = iov_len(iov, count);
+	size_t copied;
+	uint8_t *buf;
+	int i;
+
+	buf = talloc_array(mem_ctx, uint8_t, len);
+	if (buf == NULL) {
+		return NULL;
+	}
+	copied = 0;
+	for (i=0; i<count; i++) {
+		memcpy(buf+copied, iov[i].iov_base, iov[i].iov_len);
+		copied += iov[i].iov_len;
+	}
+	return buf;
+}
+
+struct tevent_req *cli_smb_req_create(TALLOC_CTX *mem_ctx,
+				      struct event_context *ev,
+				      struct cli_state *cli,
+				      uint8_t smb_command,
+				      uint8_t additional_flags,
+				      uint8_t wct, uint16_t *vwv,
+				      int iov_count,
+				      struct iovec *bytes_iov)
+{
+	struct tevent_req *result;
+	struct cli_smb_state *state;
+
+	if (iov_count > MAX_SMB_IOV) {
+		/*
+		 * Should not happen :-)
+		 */
+		return NULL;
+	}
+
+	result = tevent_req_create(mem_ctx, &state, struct cli_smb_state);
+	if (result == NULL) {
+		return NULL;
+	}
+	state->ev = ev;
+	state->cli = cli;
+	state->mid = 0;		/* Set to auto-choose in cli_smb_req_send */
+	state->chain_num = 0;
+	state->chained_requests = NULL;
+
+	cli_setup_packet_buf(cli, (char *)state->header);
+	SCVAL(state->header, smb_com, smb_command);
+	SSVAL(state->header, smb_tid, cli->cnum);
+	SCVAL(state->header, smb_wct, wct);
+
+	state->vwv = vwv;
+
+	SSVAL(state->bytecount_buf, 0, iov_len(bytes_iov, iov_count));
+
+	state->iov[0].iov_base = state->header;
+	state->iov[0].iov_len  = sizeof(state->header);
+	state->iov[1].iov_base = state->vwv;
+	state->iov[1].iov_len  = wct * sizeof(uint16_t);
+	state->iov[2].iov_base = state->bytecount_buf;
+	state->iov[2].iov_len  = sizeof(uint16_t);
+
+	if (iov_count != 0) {
+		memcpy(&state->iov[3], bytes_iov,
+		       iov_count * sizeof(*bytes_iov));
+	}
+	state->iov_count = iov_count + 3;
+
+	return result;
+}
+
+static bool cli_signv(struct cli_state *cli, struct iovec *iov, int count,
+		      uint32_t *seqnum)
+{
+	uint8_t *buf;
+
+	/*
+	 * Obvious optimization: Make cli_calculate_sign_mac work with struct
+	 * iovec directly. MD5Update would do that just fine.
+	 */
+
+	if ((count <= 0) || (iov[0].iov_len < smb_wct)) {
+		return false;
+	}
+
+	buf = iov_concat(talloc_tos(), iov, count);
+	if (buf == NULL) {
+		return false;
+	}
+
+	cli_calculate_sign_mac(cli, (char *)buf, seqnum);
+	memcpy(iov[0].iov_base, buf, iov[0].iov_len);
+
+	TALLOC_FREE(buf);
+	return true;
+}
+
+static void cli_smb_sent(struct tevent_req *subreq);
+
+static bool cli_smb_req_iov_send(struct tevent_req *req,
+				 struct cli_smb_state *state,
+				 struct iovec *iov, int iov_count)
+{
+	struct tevent_req *subreq;
+
+	if (iov[0].iov_len < smb_wct) {
+		return false;
+	}
+
+	if (state->mid != 0) {
+		SSVAL(iov[0].iov_base, smb_mid, state->mid);
+	} else {
+		SSVAL(iov[0].iov_base, smb_mid, cli_alloc_mid(state->cli));
+	}
+
+	smb_setlen((char *)iov[0].iov_base, iov_len(iov, iov_count) - 4);
+
+	if (!cli_signv(state->cli, iov, iov_count, &state->seqnum)) {
+		return false;
+	}
+
+	if (cli_encryption_on(state->cli)) {
+		NTSTATUS status;
+		char *buf, *enc_buf;
+
+		buf = (char *)iov_concat(talloc_tos(), iov, iov_count);
+		if (buf == NULL) {
+			return false;
+		}
+		status = cli_encrypt_message(state->cli, (char *)buf,
+					     &enc_buf);
+		TALLOC_FREE(buf);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(0, ("Error in encrypting client message: %s\n",
+				  nt_errstr(status)));
+			return false;
+		}
+		buf = (char *)talloc_memdup(state, enc_buf,
+					    smb_len(enc_buf)+4);
+		SAFE_FREE(enc_buf);
+		if (buf == NULL) {
+			return false;
+		}
+		iov[0].iov_base = buf;
+		iov[0].iov_len = talloc_get_size(buf);
+		subreq = writev_send(state, state->ev, state->cli->outgoing,
+				     state->cli->fd, iov, 1);
+	} else {
+		subreq = writev_send(state, state->ev, state->cli->outgoing,
+				     state->cli->fd, iov, iov_count);
+	}
+	if (subreq == NULL) {
+		return false;
+	}
+	tevent_req_set_callback(subreq, cli_smb_sent, req);
+	return true;
+}
+
+bool cli_smb_req_send(struct tevent_req *req)
+{
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+
+	return cli_smb_req_iov_send(req, state, state->iov, state->iov_count);
+}
+
+struct tevent_req *cli_smb_send(TALLOC_CTX *mem_ctx,
+				struct event_context *ev,
+				struct cli_state *cli,
+				uint8_t smb_command,
+				uint8_t additional_flags,
+				uint8_t wct, uint16_t *vwv,
+				uint32_t num_bytes,
+				const uint8_t *bytes)
+{
+	struct tevent_req *req;
+	struct iovec iov;
+
+	iov.iov_base = CONST_DISCARD(char *, bytes);
+	iov.iov_len = num_bytes;
+
+	req = cli_smb_req_create(mem_ctx, ev, cli, smb_command,
+				 additional_flags, wct, vwv, 1, &iov);
+	if (req == NULL) {
+		return NULL;
+	}
+	if (!cli_smb_req_send(req)) {
+		TALLOC_FREE(req);
+	}
+	return req;
+}
+
+static void cli_smb_sent(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+	ssize_t nwritten;
+	int err;
+
+	nwritten = writev_recv(subreq, &err);
+	TALLOC_FREE(subreq);
+	if (nwritten == -1) {
+		tevent_req_nterror(req, map_nt_error_from_unix(err));
+		return;
+	}
+
+	switch (CVAL(state->header, smb_com)) {
+	case SMBtranss:
+	case SMBtranss2:
+	case SMBnttranss:
+	case SMBntcancel:
+		state->inbuf = NULL;
+		tevent_req_done(req);
+		return;
+	case SMBlockingX:
+		if ((CVAL(state->header, smb_wct) == 8) &&
+		    (CVAL(state->vwv+3, 0) == LOCKING_ANDX_OPLOCK_RELEASE)) {
+			state->inbuf = NULL;
+			tevent_req_done(req);
+			return;
+		}
+	}
+
+	if (!cli_smb_req_set_pending(req)) {
+		tevent_req_nterror(req, NT_STATUS_NO_MEMORY);
+		return;
+	}
+}
+
+static void cli_smb_received(struct tevent_req *subreq)
+{
+	struct cli_state *cli = tevent_req_callback_data(
+		subreq, struct cli_state);
+	struct tevent_req *req;
+	struct cli_smb_state *state;
+	struct tevent_context *ev;
+	NTSTATUS status;
+	uint8_t *inbuf;
+	ssize_t received;
+	int num_pending;
+	int i, err;
+	uint16_t mid;
+
+	received = read_smb_recv(subreq, talloc_tos(), &inbuf, &err);
+	TALLOC_FREE(subreq);
+	if (received == -1) {
+		status = map_nt_error_from_unix(err);
+		goto fail;
+	}
+
+	if ((IVAL(inbuf, 4) != 0x424d53ff) /* 0xFF"SMB" */
+	    && (SVAL(inbuf, 4) != 0x45ff)) /* 0xFF"E" */ {
+		DEBUG(10, ("Got non-SMB PDU\n"));
+		status = NT_STATUS_INVALID_NETWORK_RESPONSE;
+		goto fail;
+	}
+
+	if (cli_encryption_on(cli) && (CVAL(inbuf, 0) == 0)) {
+		uint16_t enc_ctx_num;
+
+		status = get_enc_ctx_num(inbuf, &enc_ctx_num);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(10, ("get_enc_ctx_num returned %s\n",
+				   nt_errstr(status)));
+			goto fail;
+		}
+
+		if (enc_ctx_num != cli->trans_enc_state->enc_ctx_num) {
+			DEBUG(10, ("wrong enc_ctx %d, expected %d\n",
+				   enc_ctx_num,
+				   cli->trans_enc_state->enc_ctx_num));
+			status = NT_STATUS_INVALID_HANDLE;
+			goto fail;
+		}
+
+		status = common_decrypt_buffer(cli->trans_enc_state,
+					       (char *)inbuf);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(10, ("common_decrypt_buffer returned %s\n",
+				   nt_errstr(status)));
+			goto fail;
+		}
+	}
+
+	mid = SVAL(inbuf, smb_mid);
+	num_pending = talloc_array_length(cli->pending);
+
+	for (i=0; i<num_pending; i++) {
+		if (mid == cli_smb_req_mid(cli->pending[i])) {
+			break;
+		}
+	}
+	if (i == num_pending) {
+		/* Dump unexpected reply */
+		TALLOC_FREE(inbuf);
+		goto done;
+	}
+
+	req = cli->pending[i];
+	state = tevent_req_data(req, struct cli_smb_state);
+	ev = state->ev;
+
+	if (!cli_check_sign_mac(cli, (char *)inbuf, state->seqnum+1)) {
+		DEBUG(10, ("cli_check_sign_mac failed\n"));
+		TALLOC_FREE(inbuf);
+		status = NT_STATUS_ACCESS_DENIED;
+		goto fail;
+	}
+
+	if (state->chained_requests == NULL) {
+		state->inbuf = talloc_move(state, &inbuf);
+		talloc_set_destructor(req, NULL);
+		cli_smb_req_destructor(req);
+		tevent_req_done(req);
+	} else {
+		struct tevent_req **chain = talloc_move(
+			talloc_tos(), &state->chained_requests);
+		int num_chained = talloc_array_length(chain);
+
+		for (i=0; i<num_chained; i++) {
+			state = tevent_req_data(chain[i], struct
+						cli_smb_state);
+			state->inbuf = inbuf;
+			state->chain_num = i;
+			tevent_req_done(chain[i]);
+		}
+		TALLOC_FREE(inbuf);
+		TALLOC_FREE(chain);
+	}
+ done:
+	if (talloc_array_length(cli->pending) > 0) {
+		/*
+		 * Set up another read request for the other pending cli_smb
+		 * requests
+		 */
+		state = tevent_req_data(cli->pending[0], struct cli_smb_state);
+		subreq = read_smb_send(cli->pending, state->ev, cli->fd);
+		if (subreq == NULL) {
+			status = NT_STATUS_NO_MEMORY;
+			goto fail;
+		}
+		tevent_req_set_callback(subreq, cli_smb_received, cli);
+	}
+	return;
+ fail:
+	/*
+	 * Cancel all pending requests. We don't do a for-loop walking
+	 * cli->pending because that array changes in
+	 * cli_smb_req_destructor().
+	 */
+	while (talloc_array_length(cli->pending) > 0) {
+		req = cli->pending[0];
+		talloc_set_destructor(req, NULL);
+		cli_smb_req_destructor(req);
+		tevent_req_nterror(req, status);
+	}
+}
+
+NTSTATUS cli_smb_recv(struct tevent_req *req, uint8_t min_wct,
+		      uint8_t *pwct, uint16_t **pvwv,
+		      uint32_t *pnum_bytes, uint8_t **pbytes)
+{
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+	NTSTATUS status = NT_STATUS_OK;
+	uint8_t cmd, wct;
+	uint16_t num_bytes;
+	size_t wct_ofs, bytes_offset;
+	int i;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		return status;
+	}
+
+	if (state->inbuf == NULL) {
+		/* This was a request without a reply */
+		return NT_STATUS_OK;
+	}
+
+	wct_ofs = smb_wct;
+	cmd = CVAL(state->inbuf, smb_com);
+
+	for (i=0; i<state->chain_num; i++) {
+		if (i < state->chain_num-1) {
+			if (cmd == 0xff) {
+				return NT_STATUS_REQUEST_ABORTED;
+			}
+			if (!is_andx_req(cmd)) {
+				return NT_STATUS_INVALID_NETWORK_RESPONSE;
+			}
+		}
+
+		if (!have_andx_command((char *)state->inbuf, wct_ofs)) {
+			/*
+			 * This request was not completed because a previous
+			 * request in the chain had received an error.
+			 */
+			return NT_STATUS_REQUEST_ABORTED;
+		}
+
+		wct_ofs = SVAL(state->inbuf, wct_ofs + 3);
+
+		/*
+		 * Skip the all-present length field. No overflow, we've just
+		 * put a 16-bit value into a size_t.
+		 */
+		wct_ofs += 4;
+
+		if (wct_ofs+2 > talloc_get_size(state->inbuf)) {
+			return NT_STATUS_INVALID_NETWORK_RESPONSE;
+		}
+
+		cmd = CVAL(state->inbuf, wct_ofs + 1);
+	}
+
+	status = cli_pull_error((char *)state->inbuf);
+
+	if (!have_andx_command((char *)state->inbuf, wct_ofs)
+	    && NT_STATUS_IS_ERR(status)) {
+		/*
+		 * The last command takes the error code. All further commands
+		 * down the requested chain will get a
+		 * NT_STATUS_REQUEST_ABORTED.
+		 */
+		return status;
+	}
+
+	wct = CVAL(state->inbuf, wct_ofs);
+	bytes_offset = wct_ofs + 1 + wct * sizeof(uint16_t);
+	num_bytes = SVAL(state->inbuf, bytes_offset);
+
+	if (wct < min_wct) {
+		return NT_STATUS_INVALID_NETWORK_RESPONSE;
+	}
+
+	/*
+	 * wct_ofs is a 16-bit value plus 4, wct is a 8-bit value, num_bytes
+	 * is a 16-bit value. So bytes_offset being size_t should be far from
+	 * wrapping.
+	 */
+	if ((bytes_offset + 2 > talloc_get_size(state->inbuf))
+	    || (bytes_offset > 0xffff)) {
+		return NT_STATUS_INVALID_NETWORK_RESPONSE;
+	}
+
+	if (pwct != NULL) {
+		*pwct = wct;
+	}
+	if (pvwv != NULL) {
+		*pvwv = (uint16_t *)(state->inbuf + wct_ofs + 1);
+	}
+	if (pnum_bytes != NULL) {
+		*pnum_bytes = num_bytes;
+	}
+	if (pbytes != NULL) {
+		*pbytes = (uint8_t *)state->inbuf + bytes_offset + 2;
+	}
+
+	return NT_STATUS_OK;
+}
+
+size_t cli_smb_wct_ofs(struct tevent_req **reqs, int num_reqs)
+{
+	size_t wct_ofs;
+	int i;
+
+	wct_ofs = smb_wct - 4;
+
+	for (i=0; i<num_reqs; i++) {
+		struct cli_smb_state *state;
+		state = tevent_req_data(reqs[i], struct cli_smb_state);
+		wct_ofs += iov_len(state->iov+1, state->iov_count-1);
+		wct_ofs = (wct_ofs + 3) & ~3;
+	}
+	return wct_ofs;
+}
+
+bool cli_smb_chain_send(struct tevent_req **reqs, int num_reqs)
+{
+	struct cli_smb_state *first_state = tevent_req_data(
+		reqs[0], struct cli_smb_state);
+	struct cli_smb_state *last_state = tevent_req_data(
+		reqs[num_reqs-1], struct cli_smb_state);
+	struct cli_smb_state *state;
+	size_t wct_offset;
+	size_t chain_padding = 0;
+	int i, iovlen;
+	struct iovec *iov = NULL;
+	struct iovec *this_iov;
+
+	iovlen = 0;
+	for (i=0; i<num_reqs; i++) {
+		state = tevent_req_data(reqs[i], struct cli_smb_state);
+		iovlen += state->iov_count;
+	}
+
+	iov = talloc_array(last_state, struct iovec, iovlen);
+	if (iov == NULL) {
+		goto fail;
+	}
+
+	first_state->chained_requests = (struct tevent_req **)talloc_memdup(
+		last_state, reqs, sizeof(*reqs) * num_reqs);
+	if (first_state->chained_requests == NULL) {
+		goto fail;
+	}
+
+	wct_offset = smb_wct - 4;
+	this_iov = iov;
+
+	for (i=0; i<num_reqs; i++) {
+		size_t next_padding = 0;
+		uint16_t *vwv;
+
+		state = tevent_req_data(reqs[i], struct cli_smb_state);
+
+		if (i < num_reqs-1) {
+			if (!is_andx_req(CVAL(state->header, smb_com))
+			    || CVAL(state->header, smb_wct) < 2) {
+				goto fail;
+			}
+		}
+
+		wct_offset += iov_len(state->iov+1, state->iov_count-1) + 1;
+		if ((wct_offset % 4) != 0) {
+			next_padding = 4 - (wct_offset % 4);
+		}
+		wct_offset += next_padding;
+		vwv = state->vwv;
+
+		if (i < num_reqs-1) {
+			struct cli_smb_state *next_state = tevent_req_data(
+				reqs[i+1], struct cli_smb_state);
+			SCVAL(vwv+0, 0, CVAL(next_state->header, smb_com));
+			SCVAL(vwv+0, 1, 0);
+			SSVAL(vwv+1, 0, wct_offset);
+		} else if (is_andx_req(CVAL(state->header, smb_com))) {
+			/* properly end the chain */
+			SCVAL(vwv+0, 0, 0xff);
+			SCVAL(vwv+0, 1, 0xff);
+			SSVAL(vwv+1, 0, 0);
+		}
+
+		if (i == 0) {
+			this_iov[0] = state->iov[0];
+		} else {
+			/*
+			 * This one is a bit subtle. We have to add
+			 * chain_padding bytes between the requests, and we
+			 * have to also include the wct field of the
+			 * subsequent requests. We use the subsequent header
+			 * for the padding, it contains the wct field in its
+			 * last byte.
+			 */
+			this_iov[0].iov_len = chain_padding+1;
+			this_iov[0].iov_base = &state->header[
+				sizeof(state->header) - this_iov[0].iov_len];
+			memset(this_iov[0].iov_base, 0, this_iov[0].iov_len-1);
+		}
+		memcpy(this_iov+1, state->iov+1,
+		       sizeof(struct iovec) * (state->iov_count-1));
+		this_iov += state->iov_count;
+		chain_padding = next_padding;
+	}
+
+	if (!cli_smb_req_iov_send(reqs[0], last_state, iov, iovlen)) {
+		goto fail;
+	}
+	return true;
+ fail:
+	TALLOC_FREE(iov);
+	return false;
+}
+
+uint8_t *cli_smb_inbuf(struct tevent_req *req)
+{
+	struct cli_smb_state *state = tevent_req_data(
+		req, struct cli_smb_state);
+	return state->inbuf;
+}
+
+bool cli_has_async_calls(struct cli_state *cli)
+{
+	return ((tevent_queue_length(cli->outgoing) != 0)
+		|| (talloc_array_length(cli->pending) != 0));
+}
diff --git a/source3/libsmb/clientgen.c b/source3/libsmb/clientgen.c
index 6186387076..450a7cf4cd 100644
--- a/source3/libsmb/clientgen.c
+++ b/source3/libsmb/clientgen.c
@@ -650,6 +650,12 @@ struct cli_state *cli_initialise_ex(int signing_state)
 		goto error;
 	}
 
+	cli->outgoing = tevent_queue_create(cli, "cli_outgoing");
+	if (cli->outgoing == NULL) {
+		goto error;
+	}
+	cli->pending = NULL;
+
 	cli->initialised = 1;
 
 	return cli;
@@ -740,6 +746,12 @@ void cli_shutdown(struct cli_state *cli)
 	cli->fd = -1;
 	cli->smb_rw_error = SMB_READ_OK;
 
+	/*
+	 * Need to free pending first, they remove themselves
+	 */
+	while (cli->pending) {
+		talloc_free(cli->pending[0]);
+	}
 	TALLOC_FREE(cli);
 }