Re: Retrieving IP address of Client

Hi,

I wanted to retrieve the IP address of client signing on to the AS400. I
took this code from IBM technical document (# 457529679) and compiled it and
ran it.

It did not work. The data area was created, but it was blanks. I am a
complete novice in the world of API's. Anyone has any ideas, what the
problem could be? Running it in debug mode showed that the retrieveIPAddress
function was unsuccessful (returned a -1). I compiled it on V5R3 (did not
get it from the ftp site).

************************************************************************************************
Document Title:Retrieving the Client IP Address in a User Exit Program
Document Description:
A common request for exit programs that monitor the IBM(R) i5/OS™ host
servers is how the IP address of the client that is making the connection
can be determined. This used to be a very difficult programming challenge
and, for the most part, exit program designers elected to not require the
IP address in an exit program. However, there is a behavior of the i5/OS™
sockets code that can be taken advantage of to obtain the IP address of the
client without too much difficulty. In current releases of i5/OS™, socket
descriptors (a programming handle to a TCP socket) are issued beginning at
number 0 for each job. Because the host server opens the first socket in
the job, it is known that socket descriptor 0 can be used to obtain
information about the TCP socket over which the host server is
communicating. By issuing a call to the getpeername API using socket
descriptor 0, the IP address of the client can be determined.

Following is the source code for a C program that could be called by an
exit program. It logs the IP address of the client in a data area in the
QTEMP library. The exit program could then read the data area to determine
if there are any restrictions for that particular IP address. A typical
usage would be to use a CL program and the RTVDTAARA command to read the
contents of the data area.
/* Licensed Material - Property of IBM */

/******************************************************************************/

/* RTVIPA is a sample program that demonstrates how the remote IP address
can */
/* be retrieved when running in the context of a host server job. This
*/
/* sample will create a data area named QTEMP/IPADDRESS that can be
easily */
/* read by a CL exit program. The CL program should call this sample
program */
/* to retrieve the IP address, and then read the data area for any checks
of */
/* the address. */

/******************************************************************************/

#include <string.h> /* Used for memset() API */
#include <stdlib.h> /* Used for the system() API */
#include <stdio.h> /* Used for sprintf() API */
#include <xxdtaa.h> /* Used for the QXXCHDA() API */
#include <sys/socket.h> /* Used for the getpeername() API */
#include <sys/types.h> /* Co-req for the getpeername() API */


/******************************************************************************/

/* Function prototypes. */

/******************************************************************************/

int createDataArea();
void retrieveIPAddress();
void writeAddressToDataArea(char* ipaddr);


/******************************************************************************/

/* Main method. */

/******************************************************************************/

void main()
{
int rc;
rc = createDataArea();
if(rc==0) retrieveIPAddress();
}


/******************************************************************************/

/* Create the data area to store the IP address that will be retrieved
from */
/* the sockets API. */
/* @return int Negative if create fails. Otherwise 0. */

/******************************************************************************/

int createDataArea()
{
int rc;
system("DLTDTAARA DTAARA(QTEMP/IPADDRESS)");
/* Longest possible address '111.111.111.111' (at least for IPv4) */
rc = system("CRTDTAARA DTAARA(QTEMP/IPADDRESS) TYPE(*CHAR) LEN
(15)");
if(rc!=0) return -1; /* System returns 1 for unsuccessful
command */
else return 0;
}


/******************************************************************************/

/* Attempt to retrieve the remote IP address associated with socket */
/* descriptor 0, and update the data area if successful. */

/******************************************************************************/

void retrieveIPAddress()
{
int rc; /* Return code variable */
struct sockaddr address; /* Pointer to address structure */
int avail = sizeof(address); /* Needed for API call */
rc = getpeername(0, /* Use socket
descriptor 0 */
&address, /* Address structure.
*/
&avail); /* Amount of data
avail. */
if(rc==0) writeAddressToDataArea(((char*)&address)+4);
}


/******************************************************************************/

/* Write the retrieved IP address to the data area in QTEMP for later
*/
/* retrieval by the calling program.
*/
/* @param char* A char pointer that points to the 4 byte IPv4 address.
*/

/******************************************************************************/

void writeAddressToDataArea(char* ipaddr)
{
char buffer[16]; /* Create a buffer to build
string.*/
_DTAA_NAME_T dtaname = {"IPADDRESS ", "QTEMP "};
memset(buffer, '\0', sizeof(buffer)); /* Initialize data buffer to
nulls */
sprintf(buffer, "%d.%d.%d.%d",
*((unsigned char*)(ipaddr)),
*((unsigned char*)(ipaddr+1)),
*((unsigned char*)(ipaddr+2)),
*((unsigned char*)(ipaddr+3)));
QXXCHGDA(dtaname, /* Name of data area */
1, /* Starting position in data
area */
strlen(buffer), /* Number of chars to write.
*/
buffer); /* Data buffer */
}




A compiled version may also be found for V5R3 at the following location:

ftp://testcase.software.ibm.com/fromibm/os400/ApiSamples/RTVIPA.SAVF


*********************************************************************************************

Thanks in advance for any help.