r7782: fixed an ordering problem with smb requests. I found this when I had "sam database"

set to the internal ldap server over loopback. The following happened:

  - DCERPC_AUTH3 request
     - auth requests calls ldb
     - ldb calls ldap
     - ldap calls our internal ldap server, triggering events
  - samrConnect from client
     - connect refused
  - SMBclose from client
     - causes dcerpc_pipe to be destroyed
  - AUTH3 continues
     - dies on freed pipe

I chose this solution as it provides a guarantee that backends only have to think about
async issues when they mark a request async. When they don't, this code guarantees that
a second request won't happen on the same connection while processing the first one

2 files changed, 16 insertions, 0 deletions

diff --git a/source/smb_server/smb_server.c b/source/smb_server/smb_server.c
index 3b4d06f3b27..7e0aa2c0cbd 100644
--- a/source/smb_server/smb_server.c
+++ b/source/smb_server/smb_server.c
@@ -665,7 +665,18 @@ static void smbsrv_recv(struct stream_connection *conn, uint16_t flags)
 
 	DEBUG(10,("smbsrv_recv\n"));
 
+	/* our backends are designed to process one request at a time,
+	   unless they deliberately mark the request as async and
+	   process it later on a timer or other event. This enforces
+	   that ordering. */
+	if (smb_conn->processing) {
+		EVENT_FD_NOT_READABLE(conn->event.fde);
+		return;
+	}
+
+	smb_conn->processing = True;
 	status = receive_smb_request(smb_conn);
+	smb_conn->processing = False;
 	if (NT_STATUS_IS_ERR(status)) {
 		talloc_free(conn->event.fde);
 		conn->event.fde = NULL;
@@ -673,6 +684,8 @@ static void smbsrv_recv(struct stream_connection *conn, uint16_t flags)
 		return;
 	}
 
+	EVENT_FD_READABLE(conn->event.fde);
+
 	/* free up temporary memory */
 	lp_talloc_free();
 }
@@ -749,6 +762,7 @@ static void smbsrv_accept(struct stream_connection *conn)
 	smbsrv_tcon_init(smb_conn);
 
 	smb_conn->connection = conn;
+	smb_conn->processing = False;
 
 	conn->private = smb_conn;
 }
diff --git a/source/smb_server/smb_server.h b/source/smb_server/smb_server.h
index 01222adc0c4..a8e9d7ed341 100644
--- a/source/smb_server/smb_server.h
+++ b/source/smb_server/smb_server.h
@@ -254,4 +254,6 @@ struct smbsrv_connection {
 		struct smb_trans2 *trans;
 		uint8_t command;
 	} *trans_partial;
+
+	BOOL processing;
 };