s3: Basic infrastructure for /tmp/.nmbd/unexpected

This provides the framework to replace the unexpected.tdb file. Nmbd will
listen on /tmp/.nmbd/unexpected. A client interested in unexpected packets
connects there. It sends a nb_packet_query plus a potential mailslot name for
dgram packets. It waits for a single ack byte to avoid races. After that has
happened, nmbd will pass down all matching packets through that socket.

nb_packet_server_create and nb_packet_dispatch are the nmbd routines,
nb_packet_reader_send/recv and nb_packet_read_send/recv are the client ones.

1 files changed, 677 insertions, 0 deletions

diff --git a/source3/libsmb/unexpected.c b/source3/libsmb/unexpected.c
index 3934cba13d..ce1e31dc59 100644
--- a/source3/libsmb/unexpected.c
+++ b/source3/libsmb/unexpected.c
@@ -19,6 +19,7 @@
 */
 
 #include "includes.h"
+#include "lib/async_req/async_sock.h"
 
 static struct tdb_wrap *tdbd = NULL;
 
@@ -333,3 +334,679 @@ struct packet_struct *receive_unexpected(enum packet_type packet_type, int id,
 
 	return state.matched_packet;
 }
+
+static const char *nmbd_socket_dir(void)
+{
+	return lp_parm_const_string(-1, "nmbd", "socket dir", "/tmp/.nmbd");
+}
+
+struct nb_packet_query {
+	enum packet_type type;
+	size_t mailslot_namelen;
+	int trn_id;
+};
+
+struct nb_packet_client;
+
+struct nb_packet_server {
+	struct tevent_context *ev;
+	int listen_sock;
+	int max_clients;
+	int num_clients;
+	struct nb_packet_client *clients;
+};
+
+struct nb_packet_client {
+	struct nb_packet_client *prev, *next;
+	struct nb_packet_server *server;
+
+	enum packet_type type;
+	int trn_id;
+	char *mailslot_name;
+
+	int sock;
+	struct tevent_req *read_req;
+	struct tevent_queue *out_queue;
+};
+
+static int nb_packet_server_destructor(struct nb_packet_server *s);
+static void nb_packet_server_listener(struct tevent_context *ev,
+				      struct tevent_fd *fde,
+				      uint16_t flags,
+				      void *private_data);
+
+NTSTATUS nb_packet_server_create(TALLOC_CTX *mem_ctx,
+				 struct tevent_context *ev,
+				 int max_clients,
+				 struct nb_packet_server **presult)
+{
+	struct nb_packet_server *result;
+	struct tevent_fd *fde;
+	NTSTATUS status;
+
+	result = TALLOC_ZERO_P(mem_ctx, struct nb_packet_server);
+	if (result == NULL) {
+		status = NT_STATUS_NO_MEMORY;
+		goto fail;
+	}
+	result->ev = ev;
+	result->max_clients = max_clients;
+
+	result->listen_sock = create_pipe_sock(
+		nmbd_socket_dir(), "unexpected", 0755);
+	if (result->listen_sock == -1) {
+		status = map_nt_error_from_unix(errno);
+		goto fail;
+	}
+	talloc_set_destructor(result, nb_packet_server_destructor);
+
+	fde = tevent_add_fd(ev, result, result->listen_sock, TEVENT_FD_READ,
+			    nb_packet_server_listener, result);
+	if (fde == NULL) {
+		status = NT_STATUS_NO_MEMORY;
+		goto fail;
+	}
+
+	*presult = result;
+	return NT_STATUS_OK;
+fail:
+	TALLOC_FREE(result);
+	return status;
+}
+
+static int nb_packet_server_destructor(struct nb_packet_server *s)
+{
+	if (s->listen_sock != -1) {
+		close(s->listen_sock);
+		s->listen_sock = -1;
+	}
+	return 0;
+}
+
+static int nb_packet_client_destructor(struct nb_packet_client *c);
+static ssize_t nb_packet_client_more(uint8_t *buf, size_t buflen,
+				     void *private_data);
+static void nb_packet_got_query(struct tevent_req *req);
+static void nb_packet_client_read_done(struct tevent_req *req);
+
+static void nb_packet_server_listener(struct tevent_context *ev,
+				      struct tevent_fd *fde,
+				      uint16_t flags,
+				      void *private_data)
+{
+	struct nb_packet_server *server = talloc_get_type_abort(
+		private_data, struct nb_packet_server);
+	struct nb_packet_client *client;
+	struct tevent_req *req;
+	struct sockaddr_un sunaddr;
+	socklen_t len;
+	int sock;
+
+	len = sizeof(sunaddr);
+
+	sock = accept(server->listen_sock, (struct sockaddr *)(void *)&sunaddr,
+		      &len);
+	if (sock == -1) {
+		return;
+	}
+	DEBUG(6,("accepted socket %d\n", sock));
+
+	client = TALLOC_ZERO_P(server, struct nb_packet_client);
+	if (client == NULL) {
+		DEBUG(10, ("talloc failed\n"));
+		close(sock);
+		return;
+	}
+	client->sock = sock;
+	client->server = server;
+	talloc_set_destructor(client, nb_packet_client_destructor);
+
+	client->out_queue = tevent_queue_create(
+		client, "unexpected packet output");
+	if (client->out_queue == NULL) {
+		DEBUG(10, ("tevent_queue_create failed\n"));
+		TALLOC_FREE(client);
+		return;
+	}
+
+	req = read_packet_send(client, ev, client->sock,
+			       sizeof(struct nb_packet_query),
+			       nb_packet_client_more, NULL);
+	if (req == NULL) {
+		DEBUG(10, ("read_packet_send failed\n"));
+		TALLOC_FREE(client);
+		return;
+	}
+	tevent_req_set_callback(req, nb_packet_got_query, client);
+
+	DLIST_ADD(server->clients, client);
+	server->num_clients += 1;
+}
+
+static ssize_t nb_packet_client_more(uint8_t *buf, size_t buflen,
+				     void *private_data)
+{
+	struct nb_packet_query q;
+	if (buflen > sizeof(struct nb_packet_query)) {
+		return 0;
+	}
+	/* Take care of alignment */
+	memcpy(&q, buf, sizeof(q));
+	if (q.mailslot_namelen > 1024) {
+		DEBUG(10, ("Got invalid mailslot namelen %d\n",
+			   (int)q.mailslot_namelen));
+		return -1;
+	}
+	return q.mailslot_namelen;
+}
+
+static int nb_packet_client_destructor(struct nb_packet_client *c)
+{
+	if (c->sock != -1) {
+		close(c->sock);
+		c->sock = -1;
+	}
+	DLIST_REMOVE(c->server->clients, c);
+	c->server->num_clients -= 1;
+	return 0;
+}
+
+static void nb_packet_got_query(struct tevent_req *req)
+{
+	struct nb_packet_client *client = tevent_req_callback_data(
+		req, struct nb_packet_client);
+	struct nb_packet_query q;
+	uint8_t *buf;
+	ssize_t nread, nwritten;
+	int err;
+	char c;
+
+	nread = read_packet_recv(req, talloc_tos(), &buf, &err);
+	TALLOC_FREE(req);
+	if (nread < sizeof(struct nb_packet_query)) {
+		DEBUG(10, ("read_packet_recv returned %d (%s)\n",
+			   (int)nread,
+			   (nread == -1) ? strerror(err) : "wrong length"));
+		TALLOC_FREE(client);
+		return;
+	}
+
+	/* Take care of alignment */
+	memcpy(&q, buf, sizeof(q));
+
+	if (nread != sizeof(struct nb_packet_query) + q.mailslot_namelen) {
+		DEBUG(10, ("nb_packet_got_query: Invalid mailslot namelength\n"));
+		TALLOC_FREE(client);
+		return;
+	}
+
+	client->trn_id = q.trn_id;
+	client->type = q.type;
+	if (q.mailslot_namelen > 0) {
+		client->mailslot_name = talloc_strndup(
+			client, (char *)buf + sizeof(q),
+			q.mailslot_namelen);
+		if (client->mailslot_name == NULL) {
+			TALLOC_FREE(client);
+			return;
+		}
+	}
+
+	/*
+	 * Yes, this is a blocking write of 1 byte into a unix
+	 * domain socket that has never been written to. Highly
+	 * unlikely that this actually blocks.
+	 */
+	c = 0;
+	nwritten = sys_write(client->sock, &c, sizeof(c));
+	if (nwritten != sizeof(c)) {
+		DEBUG(10, ("Could not write success indicator to client: %s\n",
+			   strerror(errno)));
+		TALLOC_FREE(client);
+		return;
+	}
+
+	client->read_req = read_packet_send(client, client->server->ev,
+					    client->sock, 1, NULL, NULL);
+	if (client->read_req == NULL) {
+		DEBUG(10, ("Could not activate reader for client exit "
+			   "detection\n"));
+		TALLOC_FREE(client);
+		return;
+	}
+	tevent_req_set_callback(client->read_req, nb_packet_client_read_done,
+				client);
+}
+
+static void nb_packet_client_read_done(struct tevent_req *req)
+{
+	struct nb_packet_client *client = tevent_req_callback_data(
+		req, struct nb_packet_client);
+	ssize_t nread;
+	uint8_t *buf;
+	int err;
+
+	nread = read_packet_recv(req, talloc_tos(), &buf, &err);
+	TALLOC_FREE(req);
+	if (nread == 1) {
+		DEBUG(10, ("Protocol error, received data on write-only "
+			   "unexpected socket: 0x%2.2x\n", (*buf)));
+	}
+	TALLOC_FREE(client);
+}
+
+static void nb_packet_client_send(struct nb_packet_client *client,
+				  struct packet_struct *p);
+
+void nb_packet_dispatch(struct nb_packet_server *server,
+			struct packet_struct *p)
+{
+	struct nb_packet_client *c;
+	uint16_t trn_id;
+
+	switch (p->packet_type) {
+	case NMB_PACKET:
+		trn_id = p->packet.nmb.header.name_trn_id;
+		break;
+	case DGRAM_PACKET:
+		trn_id = p->packet.dgram.header.dgm_id;
+		break;
+	default:
+		DEBUG(10, ("Got invalid packet type %d\n",
+			   (int)p->packet_type));
+		return;
+	}
+	for (c = server->clients; c != NULL; c = c->next) {
+
+		if (c->type != p->packet_type) {
+			DEBUG(10, ("client expects packet %d, got %d\n",
+				   c->type, p->packet_type));
+			continue;
+		}
+
+		if (p->packet_type == NMB_PACKET) {
+			/*
+			 * See if the client specified transaction
+			 * ID. Filter if it did.
+			 */
+			if ((c->trn_id != -1) &&
+			    (c->trn_id != trn_id)) {
+				DEBUG(10, ("client expects trn %d, got %d\n",
+					   c->trn_id, trn_id));
+				continue;
+			}
+		} else {
+			/*
+			 * See if the client specified a mailslot
+			 * name. Filter if it did.
+			 */
+			if ((c->mailslot_name != NULL) &&
+			    !match_mailslot_name(p, c->mailslot_name)) {
+				continue;
+			}
+		}
+		nb_packet_client_send(c, p);
+	}
+}
+
+struct nb_packet_client_header {
+	size_t len;
+	enum packet_type type;
+	time_t timestamp;
+	struct in_addr ip;
+	int port;
+};
+
+struct nb_packet_client_state {
+	struct nb_packet_client *client;
+	struct iovec iov[2];
+	struct nb_packet_client_header hdr;
+	char buf[1024];
+};
+
+static void nb_packet_client_send_done(struct tevent_req *req);
+
+static void nb_packet_client_send(struct nb_packet_client *client,
+				  struct packet_struct *p)
+{
+	struct nb_packet_client_state *state;
+	struct tevent_req *req;
+
+	state = TALLOC_ZERO_P(client, struct nb_packet_client_state);
+	if (state == NULL) {
+		DEBUG(10, ("talloc failed\n"));
+		return;
+	}
+
+	state->client = client;
+
+	state->hdr.ip = p->ip;
+	state->hdr.port = p->port;
+	state->hdr.timestamp = p->timestamp;
+	state->hdr.type = p->packet_type;
+	state->hdr.len = build_packet(state->buf, sizeof(state->buf), p);
+
+	state->iov[0].iov_base = &state->hdr;
+	state->iov[0].iov_len = sizeof(state->hdr);
+	state->iov[1].iov_base = state->buf;
+	state->iov[1].iov_len = state->hdr.len;
+
+	TALLOC_FREE(client->read_req);
+
+	req = writev_send(client, client->server->ev, client->out_queue,
+			  client->sock, true, state->iov, 2);
+	if (req == NULL) {
+		DEBUG(10, ("writev_send failed\n"));
+		return;
+	}
+	tevent_req_set_callback(req, nb_packet_client_send_done, state);
+}
+
+static void nb_packet_client_send_done(struct tevent_req *req)
+{
+	struct nb_packet_client_state *state = tevent_req_callback_data(
+		req, struct nb_packet_client_state);
+	struct nb_packet_client *client = state->client;
+	ssize_t nwritten;
+	int err;
+
+	nwritten = writev_recv(req, &err);
+
+	TALLOC_FREE(req);
+	TALLOC_FREE(state);
+
+	if (nwritten == -1) {
+		DEBUG(10, ("writev failed: %s\n", strerror(err)));
+		TALLOC_FREE(client);
+	}
+
+	if (tevent_queue_length(client->out_queue) == 0) {
+		client->read_req = read_packet_send(client, client->server->ev,
+						    client->sock, 1,
+						    NULL, NULL);
+		if (client->read_req == NULL) {
+			DEBUG(10, ("Could not activate reader for client exit "
+				   "detection\n"));
+			TALLOC_FREE(client);
+			return;
+		}
+		tevent_req_set_callback(client->read_req,
+					nb_packet_client_read_done,
+					client);
+	}
+}
+
+struct nb_packet_reader {
+	int sock;
+};
+
+struct nb_packet_reader_state {
+	struct tevent_context *ev;
+	struct sockaddr_un addr;
+	struct nb_packet_query query;
+	const char *mailslot_name;
+	struct iovec iov[2];
+	char c;
+	struct nb_packet_reader *reader;
+};
+
+static int nb_packet_reader_destructor(struct nb_packet_reader *r);
+static void nb_packet_reader_connected(struct tevent_req *subreq);
+static void nb_packet_reader_sent_query(struct tevent_req *subreq);
+static void nb_packet_reader_got_ack(struct tevent_req *subreq);
+
+struct tevent_req *nb_packet_reader_send(TALLOC_CTX *mem_ctx,
+					 struct tevent_context *ev,
+					 enum packet_type type,
+					 int trn_id,
+					 const char *mailslot_name)
+{
+	struct tevent_req *req, *subreq;
+	struct nb_packet_reader_state *state;
+	char *path;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct nb_packet_reader_state);
+	if (req == NULL) {
+		return NULL;
+	}
+	state->ev = ev;
+	state->query.trn_id = trn_id;
+	state->query.type = type;
+	state->mailslot_name = mailslot_name;
+
+	if (mailslot_name != NULL) {
+		state->query.mailslot_namelen = strlen(mailslot_name);
+	}
+
+	state->reader = TALLOC_ZERO_P(state, struct nb_packet_reader);
+	if (tevent_req_nomem(state->reader, req)) {
+		return tevent_req_post(req, ev);
+	}
+
+	path = talloc_asprintf(talloc_tos(), "%s/%s", nmbd_socket_dir(),
+			       "unexpected");
+	if (tevent_req_nomem(path, req)) {
+		return tevent_req_post(req, ev);
+	}
+	state->addr.sun_family = AF_UNIX;
+	strlcpy(state->addr.sun_path, path, sizeof(state->addr.sun_path));
+	TALLOC_FREE(path);
+
+	state->reader->sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (state->reader->sock == -1) {
+		tevent_req_nterror(req, map_nt_error_from_unix(errno));
+		return tevent_req_post(req, ev);
+	}
+	talloc_set_destructor(state->reader, nb_packet_reader_destructor);
+
+	subreq = async_connect_send(state, ev, state->reader->sock,
+				    (struct sockaddr *)(void *)&state->addr,
+				    sizeof(state->addr));
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, nb_packet_reader_connected, req);
+	return req;
+}
+
+static int nb_packet_reader_destructor(struct nb_packet_reader *r)
+{
+	if (r->sock != -1) {
+		close(r->sock);
+		r->sock = -1;
+	}
+	return 0;
+}
+
+static void nb_packet_reader_connected(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct nb_packet_reader_state *state = tevent_req_data(
+		req, struct nb_packet_reader_state);
+	int res, err;
+	int num_iovecs = 1;
+
+	res = async_connect_recv(subreq, &err);
+	TALLOC_FREE(subreq);
+	if (res == -1) {
+		DEBUG(10, ("async_connect failed: %s\n", strerror(err)));
+		tevent_req_nterror(req, map_nt_error_from_unix(err));
+		return;
+	}
+
+	state->iov[0].iov_base = &state->query;
+	state->iov[0].iov_len = sizeof(state->query);
+
+	if (state->mailslot_name != NULL) {
+		num_iovecs = 2;
+		state->iov[1].iov_base = discard_const_p(
+			char, state->mailslot_name);
+		state->iov[1].iov_len = state->query.mailslot_namelen;
+	}
+
+	subreq = writev_send(state, state->ev, NULL, state->reader->sock,
+			     true, state->iov, num_iovecs);
+	if (tevent_req_nomem(subreq, req)) {
+		return;
+	}
+	tevent_req_set_callback(subreq, nb_packet_reader_sent_query, req);
+}
+
+static void nb_packet_reader_sent_query(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct nb_packet_reader_state *state = tevent_req_data(
+		req, struct nb_packet_reader_state);
+	ssize_t written;
+	int err;
+
+	written = writev_recv(subreq, &err);
+	TALLOC_FREE(subreq);
+	if (written == -1) {
+		tevent_req_nterror(req, map_nt_error_from_unix(err));
+		return;
+	}
+	if (written != sizeof(state->query) + state->query.mailslot_namelen) {
+		tevent_req_nterror(req, NT_STATUS_UNEXPECTED_IO_ERROR);
+		return;
+	}
+	subreq = read_packet_send(state, state->ev, state->reader->sock,
+				  sizeof(state->c), NULL, NULL);
+	if (tevent_req_nomem(subreq, req)) {
+		return;
+	}
+	tevent_req_set_callback(subreq, nb_packet_reader_got_ack, req);
+}
+
+static void nb_packet_reader_got_ack(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct nb_packet_reader_state *state = tevent_req_data(
+		req, struct nb_packet_reader_state);
+	ssize_t nread;
+	int err;
+	uint8_t *buf;
+
+	nread = read_packet_recv(subreq, state, &buf, &err);
+	TALLOC_FREE(subreq);
+	if (nread == -1) {
+		DEBUG(10, ("read_packet_recv returned %s\n",
+			   strerror(err)));
+		tevent_req_nterror(req, map_nt_error_from_unix(err));
+		return;
+	}
+	if (nread != sizeof(state->c)) {
+		DEBUG(10, ("read = %d, expected %d\n", (int)nread,
+			   (int)sizeof(state->c)));
+		tevent_req_nterror(req, NT_STATUS_UNEXPECTED_IO_ERROR);
+		return;
+	}
+	tevent_req_done(req);
+}
+
+NTSTATUS nb_packet_reader_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
+			       struct nb_packet_reader **preader)
+{
+	struct nb_packet_reader_state *state = tevent_req_data(
+		req, struct nb_packet_reader_state);
+	NTSTATUS status;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		return status;
+	}
+	*preader = talloc_move(mem_ctx, &state->reader);
+	return NT_STATUS_OK;
+}
+
+struct nb_packet_read_state {
+	struct nb_packet_client_header hdr;
+	uint8_t *buf;
+	size_t buflen;
+};
+
+static ssize_t nb_packet_read_more(uint8_t *buf, size_t buflen, void *p);
+static void nb_packet_read_done(struct tevent_req *subreq);
+
+struct tevent_req *nb_packet_read_send(TALLOC_CTX *mem_ctx,
+				       struct tevent_context *ev,
+				       struct nb_packet_reader *reader)
+{
+	struct tevent_req *req, *subreq;
+	struct nb_packet_read_state *state;
+
+	req = tevent_req_create(mem_ctx, &state, struct nb_packet_read_state);
+	if (req == NULL) {
+		return NULL;
+	}
+	subreq = read_packet_send(state, ev, reader->sock,
+				  sizeof(struct nb_packet_client_header),
+				  nb_packet_read_more, state);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, nb_packet_read_done, req);
+	return req;
+}
+
+static ssize_t nb_packet_read_more(uint8_t *buf, size_t buflen, void *p)
+{
+	struct nb_packet_read_state *state = talloc_get_type_abort(
+		p, struct nb_packet_read_state);
+
+	if (buflen > sizeof(struct nb_packet_client_header)) {
+		/*
+		 * Been here, done
+		 */
+		return 0;
+	}
+	memcpy(&state->hdr, buf, sizeof(struct nb_packet_client_header));
+	return state->hdr.len;
+}
+
+static void nb_packet_read_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct nb_packet_read_state *state = tevent_req_data(
+		req, struct nb_packet_read_state);
+	ssize_t nread;
+	int err;
+
+	nread = read_packet_recv(subreq, state, &state->buf, &err);
+	if (nread == -1) {
+		tevent_req_nterror(req, map_nt_error_from_unix(err));
+		return;
+	}
+	state->buflen = nread;
+	tevent_req_done(req);
+}
+
+NTSTATUS nb_packet_read_recv(struct tevent_req *req,
+			     struct packet_struct **ppacket)
+{
+	struct nb_packet_read_state *state = tevent_req_data(
+		req, struct nb_packet_read_state);
+	struct nb_packet_client_header hdr;
+	struct packet_struct *packet;
+	NTSTATUS status;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		return status;
+	}
+
+	memcpy(&hdr, state->buf, sizeof(hdr));
+
+	packet = parse_packet(
+		(char *)state->buf + sizeof(struct nb_packet_client_header),
+		state->buflen - sizeof(struct nb_packet_client_header),
+		state->hdr.type, state->hdr.ip, state->hdr.port);
+	if (packet == NULL) {
+		return NT_STATUS_INVALID_NETWORK_RESPONSE;
+	}
+	*ppacket = packet;
+	return NT_STATUS_OK;
+}