14. Appendix A PHP examples

14.1 PostgreSQL large object Example

Submitted by: PHP code exchange px@sklar.com To get this file, in the web-browser, save this file as 'Text' type as pgsql_largeobj.lib

PX: PHP Code Exchange - PostgreSQL large object access

<?
        $database = pg_Connect ( "",  "",  "",  "",  "jacarta");
        pg_exec ($database,  "BEGIN");
        $oid = pg_locreate ($database);
        echo ( "$oid\n");
        $handle = pg_loopen ($database, $oid,  "w");
        echo ( "$handle\n");
        pg_lowrite ($handle,  "foo");
        pg_loclose ($handle);
        pg_exec ($database,  "COMMIT");
        pg_close ($database);
?>

14.2 User authentication Example

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From the PHP 3 Manual: Works only if PHP is an Apache module. Instead of simply printing out the $PHP_AUTH_USER and $PHP_AUTH_PW, you would probably want to check the username and password for validity. Perhaps by sending a query to a database, or by looking up the user in a dbm file.

<?php
        if (!$PHP_AUTH_USER)
        {
                Header("WWW-authenticate: basic realm=\"My Realm\"");
                Header("HTTP/1.0 401 Unauthorized");
                echo "Text to send if user hits Cancel button\n";
                exit;
        }
        else
        {
                echo "Hello $PHP_AUTH_USER.<P>";
                echo "You entered $PHP_AUTH_PW as your password.<P>";
        }
?>

14.3 Network admin Example

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PHP: network adminstrator's best friend from http://www.htmlWizard.net

As a web-developer, you're probably used to such lovely tools as ping, whois, nslookup etc. But what when you need one of those utilities at a client's office and have no access to telnet? Good guess. Time to look up the functions in the "Network" section of the PHP manual.

Socket operations:

The most important function there is fsockopen(). Using this function, you can connect to any open port on a server and establish a socket connection with it. The function's syntax is as following:

        int fsockopen(string hostname, int port, int [errno], string [errstr]);

So, you could use this function to open a connection to a webserver and print out the headers:

function get_headers($host, $path = "/")
{
        $fp = fsockopen ("$host", 80, &$errnr, &$errstr) or die("$errno: $errstr");
        fputs($fp,"GET $path HTTP/1.0\n\n");
        while (!$end)
        {
                $line = fgets($fp, 2048);
                if (trim($line) == "")
                        $end = true;
                else
                        echo $line;
        }
        fclose($fp);
}

Finger: Naturally, you can also open connections to other ports. Writing a small finger client with PHP is trivial therefore. Let's change the example from above to query a finger daemon:

function finger ($host, $user)
{
        $fp = fsockopen($host, 79, &$errno, &$errstr) or die("$errno: $errstr");
        fputs($fp, "$user\n");
        while (!feof($fp))
                echo fgets($fp, 128);
        fclose($fp);
}

Whois: Querying a whois server uses the same concept:

// domain is like "phpwizard.net"
function whois($domain, $server="whois.internic.net")
{
        $fp = fsockopen ($server, 43, &$errnr, &$errstr) or die("$errno: $errstr");
        fputs($fp, "$domain\n");
        while (!feof($fp))
                echo fgets($fp, 2048);
        fclose($fp);
}

Blocking and non-blocking operations: But there's a problem with all those functions. They work fine if

1. You have a connection with low latency and
2. If the server you're connecting to is up and running.

        $fp = fsockopen($host, 79, &$errno, &$errstr) or die("$errno: [ ] $errstr");
        set_socket_blocking($fp, 0);
        fputs($fp, "$user\n");

        $stop = time() + $timeout;
        while (!feof($fp) && time() < $stop )
                echo fgets($fp, 128);
        fclose($fp);