windows-nt-4.0/private/ntos/lpc/lpccreat.c

/*++

Copyright (c) 1989  Microsoft Corporation

Module Name:

    lpccreat.c

Abstract:

    Local Inter-Process Communication (LPC) connection system services.

Author:

    Steve Wood (stevewo) 15-May-1989

Revision History:

--*/

#include "lpcp.h"

#ifdef ALLOC_PRAGMA
#pragma alloc_text(PAGE,NtCreatePort)
#endif

NTSTATUS
NtCreatePort(
    OUT PHANDLE PortHandle,
    IN POBJECT_ATTRIBUTES ObjectAttributes,
    IN ULONG MaxConnectionInfoLength,
    IN ULONG MaxMessageLength,
    IN ULONG MaxPoolUsage
    )

/*++

Routine Description:

    A server process can create a named connection port with the
    NtCreatePort service.

    A connection port is created with the name and SECURITY_DESCRIPTOR specified in the
    ObjectAttributes structure.  A handle to the connection port object
    is returned in the location pointed to by the PortHandle parameter.
    The returned handle can then be used to listen for connection
    requests to that port name, using the NtListenPort service.

    The standard object architecture defined desired access parameter is
    not necessary since this service can only create a new port, not
    access an existing port.

    Connection ports cannot be used to send and receive messages.  They
    are only valid as a parameter to the NtListenPort service.

Arguments:

    PortHandle - A pointer to a variable that will receive the
        connection port object handle value.

    ObjectAttributes - A pointer to a structure that specifies the
        name of the object, an access control list (SECURITY_DESCRIPTOR) to be applied
        to the object, and a set of object attribute flags.

    !b !u ObjectAttributes Structure

        PSTRING !f ObjectName - An optional pointer to a null terminated
            port name string.  The form of the name is
            [\name...\name]\port_name.  If no name is specified
            then an unconnected communication port is created rather
            than a connection port.  This is useful for sending and
            receiving messages between threads of a single process.

        PSECURITY_DESCRIPTOR !f AccessControlList - An optional pointer to an SECURITY_DESCRIPTOR.
            If an SECURITY_DESCRIPTOR is specified then it will be used to control
            access to the port object. If no SECURITY_DESCRIPTOR is specified, then
            any process will be allowed to access the port.

        ULONG !f Attributes - A set of flags that control the port
            object attributes.

            !_ None of the standard values are relevant for this call. !_-
            Connection ports cannot be inherited, are always placed in
            the system handle table and are exclusive to the creating
            process.  This field must be zero.  Future implementations
            might support specifying the !c OBJ_PERMANENT attribute.

    MaxMessageLength - Specifies the maximum length of messages sent or
        received on communication ports created from this connection
        port.  The value of this parameter cannot exceed
        MAX_PORTMSG_LENGTH bytes.

    MaxPoolUsage - Specifies the maximum amount of NonPaged pool used for
        message storage.

Return Value:

    return-value - Description of conditions needed to return value. - or -
    None.

--*/

{
    PLPCP_PORT_OBJECT ConnectionPort;
    HANDLE Handle;
    KPROCESSOR_MODE PreviousMode;
    NTSTATUS Status;
    BOOLEAN UnNamedPort;

    PAGED_CODE();

    //
    // Get previous processor mode and probe output arguments if necessary.
    //

    PreviousMode = KeGetPreviousMode();
    UnNamedPort = FALSE;
    if (PreviousMode != KernelMode) {
        try {
            ProbeForWriteHandle( PortHandle );

            if (ObjectAttributes->ObjectName == NULL ||
                ObjectAttributes->ObjectName->Length == 0 ||
                ObjectAttributes->ObjectName->Buffer == NULL
               ) {
                UnNamedPort = TRUE;
                }
            }
        except( EXCEPTION_EXECUTE_HANDLER ) {
            return( GetExceptionCode() );
            }
        }
    else {
        if (ObjectAttributes->ObjectName == NULL ||
            ObjectAttributes->ObjectName->Length == 0 ||
            ObjectAttributes->ObjectName->Buffer == NULL
           ) {
            UnNamedPort = TRUE;
            }
        }

    //
    // Allocate and initialize a port object.  If an object name was
    // specified, then this is a connection port.  Otherwise this is an
    // unconnected communication port that a process can use to communicate
    // between threads.
    //

    Status = ObCreateObject( PreviousMode,
                             LpcPortObjectType,
                             ObjectAttributes,
                             PreviousMode,
                             NULL,
                             (ULONG)sizeof( LPCP_PORT_OBJECT ),
                             0,
                             0,
                             (PVOID *)&ConnectionPort
                           );
    if (!NT_SUCCESS( Status )) {
        return( Status );
        }

    RtlZeroMemory( ConnectionPort, (ULONG)sizeof( LPCP_PORT_OBJECT ) );

    ConnectionPort->Length = sizeof( LPCP_PORT_OBJECT );
    ConnectionPort->ConnectionPort = ConnectionPort;
    ConnectionPort->Creator = PsGetCurrentThread()->Cid;
    InitializeListHead( &ConnectionPort->LpcReplyChainHead );
    InitializeListHead( &ConnectionPort->LpcDataInfoChainHead );

    //
    // Named ports get a connection message queue.
    //

    if (UnNamedPort) {
        ConnectionPort->Flags = UNCONNECTED_COMMUNICATION_PORT;
        ConnectionPort->ConnectedPort = ConnectionPort;
        }
    else {
        ConnectionPort->Flags = SERVER_CONNECTION_PORT;
        }

    //
    // All ports get a request message queue.
    //

    Status = LpcpInitializePortQueue( ConnectionPort );
    if (!NT_SUCCESS(Status)) {
        ObDereferenceObject( ConnectionPort );
        return(Status);
    }

    //
    // Initialize the port zone
    //

    ConnectionPort->MaxMessageLength =
        LpcpZone.Zone.BlockSize - FIELD_OFFSET( LPCP_MESSAGE, Request );
    ConnectionPort->MaxConnectionInfoLength =
        ConnectionPort->MaxMessageLength -
        sizeof( PORT_MESSAGE ) -
        sizeof( LPCP_CONNECTION_MESSAGE );

#if DBG
    LpcpTrace(( "Created port %ws (%x) - MaxMsgLen == %x  MaxConnectInfoLen == %x\n",
                UnNamedPort ? L"** UnNamed **" : ObjectAttributes->ObjectName->Buffer,
                ConnectionPort,
                ConnectionPort->MaxMessageLength,
                ConnectionPort->MaxConnectionInfoLength
             ));
#endif

    if (ConnectionPort->MaxMessageLength < MaxMessageLength) {
#if DBG
        LpcpPrint(( "MaxMessageLength granted is %x but requested %x\n",
                    ConnectionPort->MaxMessageLength,
                    MaxMessageLength
                 ));
        DbgBreakPoint();
#endif
        ObDereferenceObject( ConnectionPort );
        return STATUS_INVALID_PARAMETER_4;
        }

    if (ConnectionPort->MaxConnectionInfoLength < MaxConnectionInfoLength) {
#if DBG
        LpcpPrint(( "MaxConnectionInfoLength granted is %x but requested %x\n",
                    ConnectionPort->MaxConnectionInfoLength,
                    MaxConnectionInfoLength
                 ));
        DbgBreakPoint();
#endif
        ObDereferenceObject( ConnectionPort );
        return STATUS_INVALID_PARAMETER_3;
        }

    //
    // Insert connection port object in specified object table.  Set port
    // handle value if successful.  If not successful, then the port will
    // have been dereferenced, which will cause it to be freed, after our
    // delete procedure is called.  The delete procedure will undo the work
    // done to initialize the port.  Finally, return the system server status.
    //

    Status = ObInsertObject( ConnectionPort,
                             NULL,
                             PORT_ALL_ACCESS,
                             0,
                             (PVOID *)NULL,
                             &Handle
                           );

    if (NT_SUCCESS( Status )) {
        try {
            *PortHandle = Handle;
            }
        except( EXCEPTION_EXECUTE_HANDLER ) {
            NtClose( Handle );
            Status = GetExceptionCode();
            }
        }

    return( Status );
}