143 lines
5.9 KiB
HTML
143 lines
5.9 KiB
HTML
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Example: Worker program used for sendmsg() and recvmsg()" />
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<meta name="abstract" content="This example shows how to use the recvmsg() API client job to receive the worker jobs." />
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<meta name="description" content="This example shows how to use the recvmsg() API client job to receive the worker jobs." />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Example: Worker program used for sendmsg() and recvmsg()</title>
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</head>
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<body id="x2descriptors"><a name="x2descriptors"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Example: Worker program used for <span class="apiname">sendmsg()</span> and <span class="apiname">recvmsg()</span></h1>
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<div><p>This example shows how to use the <span class="apiname">recvmsg()</span> API
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client job to receive the worker jobs.</p>
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<div class="section"><div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms
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of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
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<pre>/**************************************************************************/
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/* Worker job that uses the recvmsg to process client requests */
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/**************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/socket.h>
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main (int argc, char *argv[])
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{
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int rc, len;
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int worker_sd, pass_sd;
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char buffer[80];
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struct iovec iov[1];
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struct msghdr msg;
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/*************************************************/
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/* One of the socket descriptors that was */
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/* returned by socketpair(), is passed to this */
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/* worker job as descriptor 0. */
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/*************************************************/
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worker_sd = 0;
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/*************************************************/
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/* Initialize message header structure */
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/*************************************************/
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memset(&msg, 0, sizeof(msg));
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memset(iov, 0, sizeof(iov));
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/*************************************************/
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/* The recvmsg() call will NOT block unless a */
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/* non-zero length data buffer is specified */
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/*************************************************/
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iov[0].iov_base = buffer;
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iov[0].iov_len = sizeof(buffer);
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msg.msg_iov = iov;
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msg.msg_iovlen = 1;
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/*************************************************/
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/* Fill in the msg_accrights fields so that we */
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/* can receive the descriptor */
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/*************************************************/
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msg.msg_accrights = (char *)&pass_sd;
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msg.msg_accrightslen = sizeof(pass_sd);
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/*************************************************/
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/* Wait for the descriptor to arrive */
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/*************************************************/
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printf("Waiting on recvmsg\n");
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rc = recvmsg(worker_sd, &msg, 0);
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if (rc < 0)
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{
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perror("recvmsg() failed");
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close(worker_sd);
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exit(-1);
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}
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else if (msg.msg_accrightslen <= 0)
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{
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printf("Descriptor was not received\n");
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close(worker_sd);
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exit(-1);
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}
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else
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{
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printf("Received descriptor = %d\n", pass_sd);
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}
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/*************************************************/
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/* Receive a message from the client */
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/*************************************************/
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printf("Wait for client to send us a message\n");
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rc = recv(pass_sd, buffer, sizeof(buffer), 0);
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if (rc <= 0)
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{
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perror("recv() failed");
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close(worker_sd);
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close(pass_sd);
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exit(-1);
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}
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printf("<%s>\n", buffer);
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/*************************************************/
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/* Echo the data back to the client */
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/*************************************************/
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printf("Echo it back\n");
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len = rc;
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rc = send(pass_sd, buffer, len, 0);
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if (rc <= 0)
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{
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perror("send() failed");
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close(worker_sd);
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close(pass_sd);
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exit(-1);
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}
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/*************************************************/
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/* Close down the descriptors */
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/*************************************************/
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close(worker_sd);
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close(pass_sd);
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}</pre>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="xdescriptors.htm" title="The sendmsg() and recvmsg() examples show how to design a server program that uses these APIs to handle incoming connections.">Example: Pass descriptors between processes</a></div>
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</div>
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</div>
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