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<title>PTypes: networking: examples</title>
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<p><a href="../index.html"><img src="title-21.png" width="253" height="39" alt="C++ Portable Types Library (PTypes) Version 2.1" border="0"></a>
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<p class="hpath"><a href="index.html">Top</a>: <a href="inet.html">Networking</a>:
Examples</p>
<p><b><br>
Example 1</b>. A simple IP client that tries to retrieve the main page at www.yahoo.com via an HTTP request. </p>
<blockquote>
<pre>
#include <pinet.h>
USING_PTYPES
int main()
{
ipstream client("www.yahoo.com", 80);
try
{
client.open();
<span class="comment">// send a valid HTTP/1.1 request</span>
client.put("GET / HTTP/1.1\r\n"<br> "Accept: * /*\r\n"<br> "User-Agent: TestAgent/1.0\r\n"<br> "Host: www.yahoo.com\r\n"<br> "Connection: close\r\n\r\n");
client.flush();
<span class="comment">// receive the response and print it line by line</span>
while (!client.get_eof())
pout.putline(client.line());
client.close();
}
catch(estream* e)
{
perr.putf("Error: %s\n", pconst(e->get_message()));
delete e;
}
return 0;
}</pre>
</blockquote>
<p><b>Example 2 </b>. This example demonstrates the basic usage of streaming network
interfaces <span class="lang">ipstream</span> and <span class="lang">ipstmserver</span>.
It consists of two programs: test client and test server. The
server handles requests that contain a single word "Hello" by sending
a response greeting back to the client. This example would work for named pipes
as well, i.e. if you replace the class names <span class="lang">ipstream</span>
and <span class="lang">ipstmserver</span> with <span class="lang">namedpipe</span>
and <span class="lang">npserver</span> and fix the construction parameters.</p>
<p><u>Client:</u></p>
<blockquote>
<pre>
#include <pinet.h>
USING_PTYPES
const int testport = 8085;
const int maxtoken = 4096;
int main()
{
<span class="comment">// create a client socket and send a greeting to the server
// assuming that the server is on the same host (127.0.0.1)</span>
ipstream client(ipaddress(127, 0, 0, 1), testport);
try
{
client.open();
pout.put("Sending a request to the server...\n");
client.putline("Hello");
client.flush();
<span class="comment">// receive the response</span>
string rsp = client.line(maxtoken);
pout.putf("Received: %s\n", pconst(rsp));
<span class="comment">// need to close the socket explicitly to gracefully shutdown
// the peer host too. otherwise, ~ipstream() will call cancel()
// and leave the peer in a waiting state (not forever though)</span>.
client.close();
}
catch(estream* e)
{
perr.putf("Error: %s\n", pconst(e->get_message()));
delete e;
}
return 0;
}</pre>
</blockquote>
<p> </p>
<p><u>Server:</u></p>
<blockquote>
<pre>
#include <ptime.h>
#include <pinet.h>
USING_PTYPES
const int testport = 8085;
const int maxtoken = 4096;
void servermain(ipstmserver& svr)
{
ipstream client;
pout.putf("Ready to answer queries on port %d\n", testport);
while(true)
{
<span class="comment">// serve() will wait for a connection request and will prepare
// the supplied ipstream object for talking to the peer.
// note that (unlikely) exceptions thrown in serve() will be
// caught in main()</span>
svr.serve(client);
<span class="comment">// for better performance the server would start a new thread
// for each client request. for simplicity, we serve the request
// in-place. see multithreading examples for the full multithreaded
// server template.</span>
if (client.get_active())
{
try
{
<span class="comment">// read the request line:
// real-world network applications should limit input data
// to prevent potential denial-of-service attacks</span>
string req = lowercase(client.line(maxtoken));
if (req == "hello")
{
<span class="comment">// try to reverse-lookup the client's IP</span>
string host = phostbyaddr(client.get_ip());
if (isempty(host))
host = iptostring(client.get_ip());
<span class="comment">// now send our greeting to the client</span>
client.putline("Hello, " + host + " ("
+ iptostring(client.get_ip()) + "), nice to see you!");
client.flush();
<span class="comment">// log this request</span>
pout.putf("%t greeting received from %s (%a)\n",
now(), pconst(host), long(client.get_ip()));
}
client.close();
}
catch(estream* e)
{
perr.putf("Error: %s\n", pconst(e->get_message()));
delete e;
}
}
}
}
int main()
{
ipstmserver svr;
try
{
<span class="comment">// bind to all local addresses on port 8085</span>
svr.bindall(testport);
<span class="comment"> // enter an infinite loop of serving requests</span>
servermain(svr);
}
catch(estream* e)
{
perr.putf("FATAL: %s\n", pconst(e->get_message()));
delete e;
}
return 0;
}
</pre>
</blockquote>
<p><b>Example 3 </b>. This example demonstrates the use of message-oriented networking
interfaces <span class="lang">ipmessage</span> and <span class="lang">ipmsgserver</span>.
The client sends a broadcast message to the local network and waits for a response.
It may retry the request several times.</p>
<p><u>Client:</u></p>
<blockquote>
<pre>
#include <pinet.h>
USING_PTYPES
const int testport = 8085;
const int maxtoken = 4096;
const int tries = 3;
const int firsttimeout = 2000;
bool dorequest(int timeout)
{
ipmessage msg(ipbcast, testport);
try
{
pout.put("Broadcasting a request...\n");
msg.send("Hello");
<span class="comment">// wait for a response the specified amount of time</span>
if (!msg.waitfor(timeout))
return false;
ipaddress src;
string rsp = msg.receive(maxtoken, src);
pout.putf("Received: '%s' (from %a)\n", pconst(rsp), long(src));
}
catch(estream* e)
{
perr.putf("Error: %s\n", pconst(e->get_message()));
delete e;
}
return true;
}
int main()
{
int timeout = firsttimeout;
for (int i = 0; i < tries; i++)
{
if (dorequest(timeout))
break;
<span class="comment">// double the timeout value</span>
timeout *= 2;
}
return 0;
}
</pre>
</blockquote>
<p> </p>
<p><u>Server:</u></p>
<blockquote>
<pre>
#include <ptime.h>
#include <pinet.h>
USING_PTYPES
const int testport = 8085;
const int maxtoken = 4096;
void servermain(ipmsgserver& svr)
{
pout.putf("Ready to answer queries on port %d\n", testport);
bool quit = false;
do
{
try
{
<span class="comment">// receive the "hello" request and send a simple answer
// back to the client</span>
string req = lowercase(svr.receive(maxtoken));
if (req == "hello")
{
string host = svr.get_host();
if (isempty(host))
host = iptostring(svr.get_ip());
svr.send("Hello, " + host + " ("
+ iptostring(svr.get_ip()) + "), nice to see you!");
<span class="comment">// log this request</span>
pout.putf("%t greeting received from %s (%a)\n",
now(), pconst(host), long(svr.get_ip()));
}
}
catch(estream* e)
{
perr.putf("Server error: %s\n", pconst(e->get_message()));
delete e;
}
} while (!quit);
}
int main()
{
ipmsgserver svr;
try
{
svr.bindall(testport);
<span class="comment">// try to listen on socket once to generate an error right away,
// before entering the main server loop</span>
svr.poll();
<span class="comment">// enter an infinite loop of serving requests</span>
servermain(svr);
}
catch(estream* e)
{
perr.putf("FATAL: %s\n", pconst(e->get_message()));
delete e;
}
return 0;
}
</pre>
</blockquote>
<p class="seealso">See also: <a href="inet.ipstream.html">ipstream</a>, <a href="inet.ipstmserver.html">ipstmserver</a>,
<a href="inet.ipmessage.html">ipmessage</a>, <a href="inet.ipmsgserver.html">ipmsgserver</a>,
<a href="inet.utils.html">Utilities</a>, <a href="async.examples.html">Multithreading
examples</a></p>
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