RpcServerUseProtseqEx function (rpcdce.h)

Article
08/19/2022

The RpcServerUseProtseqEx function tells the RPC run-time library to use the specified protocol sequence for receiving remote procedure calls.

Syntax

RPC_STATUS RpcServerUseProtseqEx(
  RPC_CSTR     Protseq,
  unsigned int MaxCalls,
  void         *SecurityDescriptor,
  PRPC_POLICY  Policy
);

Parameters

Protseq

Pointer to a string identifier of the protocol sequence to register with the RPC run-time library.

MaxCalls

Backlog queue length for the ncacn_ip_tcp protocol sequence. All other protocol sequences ignore this parameter. Use RPC_C_PROTSEQ_MAX_REQS_DEFAULT to specify the default value. See Remarks.

SecurityDescriptor

Pointer to an optional parameter provided for the Windows XP/2000/NT security subsystem. Used only for ncacn_np and ncalrpc protocol sequences. All other protocol sequences ignore this parameter. Using a security descriptor on the endpoint in order to make a server secure is not recommended. This parameter does not appear in the DCE specification for this API.

Policy

Pointer to the RPC_POLICY structure, which contains flags to restrict port allocation for dynamic ports and allow multihomed computers to selectively bind to network interface cards. The RPC_POLICY structure enables the caller to direct the RPC run-time library to use an intranet port or an Internet port, among other options.

Return value

Value	Meaning
RPC_S_OK	The call succeeded.
RPC_S_PROTSEQ_NOT_SUPPORTED	The protocol sequence is not supported on this host.
RPC_S_INVALID_RPC_PROTSEQ	The protocol sequence.
RPC_S_OUT_OF_MEMORY	The system is out of memory.
RPC_S_INVALID_SECURITY_DESC	The security descriptor is invalid.

Note For a list of valid error codes, see RPC Return Values.

Remarks

The parameters and effects of RpcServerUseProtseqEx subsume those of RpcServerUseProtseq. The difference is the Policy field, which allows you to restrict port allocation for dynamic ports and allows multihomed machines to selectively bind to network interface cards.

Setting the NICFlags field of the RPC_POLICY structure to zero makes this extended function functionally equivalent to the original RpcServerUseProtseq, and the server will bind to NICs based on the settings in the system registry. For information, see Configuring the Registry for Port Allocations and Selective Binding.

Note The flag settings in the Policy field are effective only when the ncacn_ip_tcp or ncadg_ip_udp protocol sequence is in use. For all other protocol sequences, the RPC run time ignores these values.

A server application calls RpcServerUseProtseqEx to register one protocol sequence with the RPC run-time library. To receive remote procedure call requests, a server must register at least one protocol sequence with the RPC run-time library. A server application can call RpcServerUseProtseqEx multiple times to register additional protocol sequences.

For each protocol sequence registered by a server, the RPC run-time library creates one or more endpoints through which the server receives remote procedure call requests. The RPC run-time library creates different endpoints for each protocol sequence. The endpoint name is generated by the RPC run time or the operating system. For example, for ncacn_ip_tcp, the port number is dynamically determined by the RPC run time, depending on availability and registry settings.

For MaxCalls, the value provided by the application is only a hint. The RPC run time or the Windows Sockets provider may override the value. For example, on Windows XP or Windows 2000 Professional, the value is limited to 5. Values greater than 5 are ignored and 5 is used instead. On Windows Server 2003 and Windows 2000 Server, the value will be honored.

Applications must be careful to pass reasonable values in MaxCalls. Large values on Server, Advanced Server, or Datacenter Server can cause a large amount of non-paged pool memory to be used. Using too small a value is also unfavorable, as it may result in TCP SYN packets being met by TCP RST from the server if the backlog queue gets exhausted. An application developer should balance memory footprint versus scalability requirements when determining the proper value for MaxCalls.

When the computer is configured to use selective binding, successful return does not guarantee that the server has created endpoints for all the network interfaces present on the computer. The RPC run-time may not listen on some network interfaces depending on the selective binding settings. In addition, if an interface has not yet received an IP address using DHCP, the RPC server does not listen on the network interface until a DHCP address is assigned to it. A successful return implies that the server is listening on at least one network interface; the full list of the binding handles over which remote procedure calls can be received can be obtained with a call to the RpcServerInqBindings function.

To register all protocol sequences, a server calls RpcServerUseAllProtseqsEx routine.

For more information, see Server-Side Binding.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	rpcdce.h (include Rpc.h)
Library	Rpcrt4.lib
DLL	Rpcrt4.dll