svctcp_create Subroutine

Important: The subroutine is exported from both the libc and the libnsl libraries.

svctcp_create Subroutine Exported from the libc Library

Purpose

Creates a Transmission Control Protocol/Internet Protocol (TCP/IP) service transport handle.

Library

C Library (libc.a)

Syntax

#include <rpc/rpc.h>

SVCXPRT *svctcp_create ( sock, sendsz, recvsz) int sock; u_int sendsz, rcvcsz;

Description

The svctcp_create subroutine creates a Remote Procedure Call (RPC) service transport handle based on TCP/IP and returns a pointer to it.

Since TCP/IP remote procedure calls use buffered I/O, users can set the size of the send and receive buffers with the sendsz and recvsz parameters, respectively. If the size of either buffer is set to a value of 0, the svctcp_create subroutine picks suitable default values.

By default, the RPC server uses nonblocking I/O with TCP. This behavior can be changed by setting the environment variable RPC_TCP_MODE to USEBLOCKING, which causes the TCP RPC server to use blocking I/O.

Note: Using blocking I/O leaves the server vulnerable to disruption by malicious or misconfigured clients.

Parameters

Item	Description
sock	Specifies the socket associated with the transport. If the value of the sock parameter is RPC_ANYSOCK, the svctcp_create subroutine creates a new socket. The service transport handle socket number is set to xprt->xp_sock. If the socket is not bound to a local TCP/IP port, then this routine binds the socket to an arbitrary port. Its port number is set to xprt->xp_port.
sendsz	Specifies the size of the send buffer.
recvsz	Specifies the size of the receive buffer.

Restrictions

In AIX® 5.2, the maximum number of open file descriptors that an RPC server can use has been set to 32767 so that compatibility can be maintained with RPC-server applications built on earlier releases of AIX.

Return Values

Upon successful completion, this subroutine returns a valid RPC service transport handle. If unsuccessful, it returns a value of null.

svctcp_create Subroutine Exported from the libnsl Library

Purpose

Creates a Transmission Control Protocol/Internet Protocol (TCP/IP) service transport handle.

Library

Network Services Library (libnsl.a)

Syntax

#include <rpc/rpc.h>

SVCXPRT *svctcp_create (fd, sendsz, recvsz)
int fd;
uint_t sendsz;
uint_t recvsz;

Description

The svctcp_create subroutine creates a Remote Procedure Call (RPC) service transport handle based on TCP/IP and returns a pointer to it.

Because TCP/IP remote procedure calls use buffered I/O, you can set the size of the send and receive buffers with the sendsz and recvsz parameters. If the size of either buffer is set to a value of 0, the svctcp_create subroutine picks suitable default values. The fd parameter specifies a file descriptor on a TCP transport. You can set the value of the fd parameter to RPC_ANYSOCK, so that the svctcp_create subroutine creates a new file descriptor on the TCP transport and binds the file descriptor to a port.

Use the svc_create subroutine instead of the svctcp_create subroutine. The svctcp_create subroutine is compatible only with earlier versions of AIX.

Parameters

Item	Description
fd	Specifies the file descriptor that is associated with the TCP transport.
sendsz	Specifies the size of the send buffer.
recvsz	Specifies the size of the receive buffer.

Return Values

Item	Description
a valid RPC service transport handle	successful
a null value	unsuccessful

Examples

#include <rpc/rpc.h>

static void dispatch(struct svc_req *, SVCXPRT *);

int main()
{
  SVCXPRT    *svc=NULL;
  int     fd;
  uint_t     sendsz, recvsz; 
  int     protocol = IPPROTO_TCP;

  /* Set send and recieve buffer sizes to 0 so that they are set to 
   * default values when svctcp_create() is called    
   */
  sendsz = 0;
  recvsz = 0;

  /* Set the file descriptor to RPC_ANYFD */
  fd = RPC_ANYSOCK;

  svc = (SVCXPRT *) svctcp_create(fd, sendsz, recvsz);
  if(svc==NULL)
  {
    fprintf(stderr,"svctcp_create() failed");
    exit(1);
  }

  /* create association between program & version number and dispatch routine */
  if(svc_register(svc, prognum, versnum, dispatch, protocol) == 0)
  {
    fprintf(stderr,"svc_register() failed");
    exit(1);
  }
  
  /* Accept client requests */
  svc_run();

  return 1;
}

static void dispatch(rqstp, transp)    /* remote procedure */
  struct svc_req *rqstp;
  SVCXPRT        *transp;
{
  /* Dispatch Routine Code */
}