ibm-information-center/dist/eclipse/plugins/i5OS.ic.rzab6_5.4.0.1/xip6client.htm

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<title>Example: IPv4 or IPv6 client </title>
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<h1 class="topictitle1">Example: IPv4 or IPv6 client </h1>
<div><p>This sample program can be used with the server application that
accepts requests from either IPv4 or IPv6 clients. </p>
<div class="section"><div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
<pre>/**************************************************************************/
/* This is an IPv4 or IPv6 client. */
/**************************************************************************/
/**************************************************************************/
/* Header files needed for this sample program */
/**************************************************************************/
#include &lt;stdio.h&gt;
#include &lt;string.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netdb.h&gt;
/**************************************************************************/
/* Constants used by this program */
/**************************************************************************/
#define BUFFER_LENGTH 250
#define FALSE 0
#define SERVER_NAME "ServerHostName"
/* Pass in 1 parameter which is either the */
/* address or host name of the server, or */
/* set the server name in the #define */
/* SERVER_NAME. */
void main(int argc, char *argv[])
{
/***********************************************************************/
/* Variable and structure definitions. */
/***********************************************************************/
int sd=-1, rc, bytesReceived=0;
char buffer[BUFFER_LENGTH];
char server[NETDB_MAX_HOST_NAME_LENGTH];
char servport[] = "3005";
struct in6_addr serveraddr;
struct addrinfo hints, *res=NULL;
/***********************************************************************/
/* A do/while(FALSE) loop is used to make error cleanup easier. The */
/* close() of the socket descriptor is only done once at the very end */
/* of the program along with the free of the list of addresses. */
/***********************************************************************/
do
{
/********************************************************************/
/* If an argument was passed in, use this as the server, otherwise */
/* use the #define that is located at the top of this program. */
/********************************************************************/
if (argc &gt; 1)
strcpy(server, argv[1]);
else
strcpy(server, SERVER_NAME);
memset(&amp;hints, 0x00, sizeof(hints));
hints.ai_flags = AI_NUMERICSERV;
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
/********************************************************************/
/* Check if we were provided the address of the server using */
/* inet_pton() to convert the text form of the address to binary */
/* form. If it is numeric then we want to prevent getaddrinfo() */
/* from doing any name resolution. */
/********************************************************************/
rc = inet_pton(AF_INET, server, &amp;serveraddr);
if (rc == 1) /* valid IPv4 text address? */
{
hints.ai_family = AF_INET;
hints.ai_flags |= AI_NUMERICHOST;
}
else
{
rc = inet_pton(AF_INET6, server, &amp;serveraddr);
if (rc == 1) /* valid IPv6 text address? */
{
hints.ai_family = AF_INET6;
hints.ai_flags |= AI_NUMERICHOST;
}
}
/********************************************************************/
/* Get the address information for the server using getaddrinfo(). */
/********************************************************************/
rc = getaddrinfo(server, servport, &amp;hints, &amp;res);
if (rc != 0)
{
printf("Host not found --&gt; %s\n", gai_strerror(rc));
if (rc == EAI_SYSTEM)
perror("getaddrinfo() failed");
break;
}
/********************************************************************/
/* The socket() function returns a socket descriptor representing */
/* an endpoint. The statement also identifies the address family, */
/* socket type, and protocol using the information returned from */
/* getaddrinfo(). */
/********************************************************************/
sd = socket(res-&gt;ai_family, res-&gt;ai_socktype, res-&gt;ai_protocol);
if (sd &lt; 0)
{
perror("socket() failed");
break;
}
/********************************************************************/
/* Use the connect() function to establish a connection to the */
/* server. */
/********************************************************************/
rc = connect(sd, res-&gt;ai_addr, res-&gt;ai_addrlen);
if (rc &lt; 0)
{
/*****************************************************************/
/* Note: the res is a linked list of addresses found for server. */
/* If the connect() fails to the first one, subsequent addresses */
/* (if any) in the list can be tried if required. */
/*****************************************************************/
perror("connect() failed");
break;
}
/********************************************************************/
/* Send 250 bytes of a's to the server */
/********************************************************************/
memset(buffer, 'a', sizeof(buffer));
rc = send(sd, buffer, sizeof(buffer), 0);
if (rc &lt; 0)
{
perror("send() failed");
break;
}
/********************************************************************/
/* In this example we know that the server is going to respond with */
/* the same 250 bytes that we just sent. Since we know that 250 */
/* bytes are going to be sent back to us, we can use the */
/* SO_RCVLOWAT socket option and then issue a single recv() and */
/* retrieve all of the data. */
/* */
/* The use of SO_RCVLOWAT is already illustrated in the server */
/* side of this example, so we will do something different here. */
/* The 250 bytes of the data may arrive in separate packets, */
/* therefore we will issue recv() over and over again until all */
/* 250 bytes have arrived. */
/********************************************************************/
while (bytesReceived &lt; BUFFER_LENGTH)
{
rc = recv(sd, &amp; buffer[bytesReceived],
BUFFER_LENGTH - bytesReceived, 0);
if (rc &lt; 0)
{
perror("recv() failed");
break;
}
else if (rc == 0)
{
printf("The server closed the connection\n");
break;
}
/*****************************************************************/
/* Increment the number of bytes that have been received so far */
/*****************************************************************/
bytesReceived += rc;
}
} while (FALSE);
/***********************************************************************/
/* Close down any open socket descriptors */
/***********************************************************************/
if (sd != -1)
close(sd);
/***********************************************************************/
/* Free any results returned from getaddrinfo */
/***********************************************************************/
if (res != NULL)
freeaddrinfo(res);
}</pre>
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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="ip6scen.htm" title="This topic describes a typical situation in which you might want to use the AF_INET6 address family.">Socket scenario: Create an application to accept IPv4 and IPv6 clients</a></div>
</div>
<div class="relref"><strong>Related reference</strong><br />
<div><a href="xacceptboth.htm" title="Use this sample program to create a server/client model that accepts requests from both IPv4 (those socket applications that use the AF_INET address family) and IPv6 (those applications that use the AF_INET6 address family).">Example: Accept connections from both IPv6 and IPv4 clients</a></div>
<div><a href="generic.htm" title="This code example contains the code for a common client job.">Example: Generic client</a></div>
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