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Hartmut Holzgraefe
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37
features/cookies.xml
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37
features/cookies.xml
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|
|
@ -0,0 +1,37 @@
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<chapter id="features.cookies">
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<title>Cookies</title>
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||||
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<para>
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PHP transparently supports HTTP cookies. Cookies are a mechanism
|
||||
for storing data in the remote browser and thus tracking
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||||
or identifying return users. You can set cookies using the
|
||||
<function>setcookie</function> function. Cookies are part of the
|
||||
HTTP header, so <function>setcookie</function> must be called before
|
||||
any output is sent to the browser. This is the same limitation that
|
||||
<function>header</function> has.</para>
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||||
|
||||
<para>
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||||
Any cookies sent to you from the client will automatically be
|
||||
turned into a PHP variable just like GET and POST method data. If
|
||||
you wish to assign multiple values to a single cookie, just add
|
||||
<emphasis>[]</emphasis> to the cookie name. For more details see
|
||||
the <function>setcookie</function> function.</para>
|
||||
|
||||
</chapter>
|
||||
|
||||
<!-- Keep this comment at the end of the file
|
||||
Local variables:
|
||||
mode: sgml
|
||||
sgml-omittag:t
|
||||
sgml-shorttag:t
|
||||
sgml-minimize-attributes:nil
|
||||
sgml-always-quote-attributes:t
|
||||
sgml-indent-step:1
|
||||
sgml-indent-data:t
|
||||
sgml-parent-document:nil
|
||||
sgml-default-dtd-file:"../manual.ced"
|
||||
sgml-exposed-tags:nil
|
||||
sgml-local-catalogs:nil
|
||||
sgml-local-ecat-files:nil
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||||
End:
|
||||
-->
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||||
305
features/error-handling.xml
Normal file
305
features/error-handling.xml
Normal file
|
|
@ -0,0 +1,305 @@
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|||
<chapter id="features.error-handling">
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||||
<title>Error Handling</title>
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||||
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<para>
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||||
There are several types of errors and warnings in PHP. They are:
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|
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<table>
|
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<title>PHP error types</title>
|
||||
<tgroup cols="4">
|
||||
<thead>
|
||||
<row>
|
||||
<entry>Value</entry>
|
||||
<entry>Constant</entry>
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<entry>Description</entry>
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<entry>Note</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>1</entry>
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<entry>E_ERROR</entry>
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||||
<entry>fatal run-time errors</entry>
|
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<entry></entry>
|
||||
</row>
|
||||
<row>
|
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<entry>2</entry>
|
||||
<entry>E_WARNING</entry>
|
||||
<entry>run-time warnings (non fatal errors)</entry>
|
||||
<entry></entry>
|
||||
</row>
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<row>
|
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<entry>4</entry>
|
||||
<entry>E_PARSE</entry>
|
||||
<entry>compile-time parse errors</entry>
|
||||
<entry></entry>
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</row>
|
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<row>
|
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<entry>8</entry>
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||||
<entry>E_NOTICE </entry>
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||||
<entry>
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run-time notices (less serious than warnings)
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</entry>
|
||||
<entry></entry>
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</row>
|
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<row>
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<entry>16</entry>
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<entry>E_CORE_ERROR</entry>
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<entry>fatal errors that occur during PHP's initial startup</entry>
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<entry>PHP 4 only</entry>
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</row>
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<row>
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<entry>32</entry>
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<entry>E_CORE_WARNING</entry>
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||||
<entry>
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warnings (non fatal errors) that occur during PHP's initial
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||||
startup
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||||
</entry>
|
||||
<entry>PHP 4 only</entry>
|
||||
</row>
|
||||
<row>
|
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<entry>64</entry>
|
||||
<entry>E_COMPILE_ERROR</entry>
|
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<entry>fatal compile-time errors</entry>
|
||||
<entry>PHP 4 only</entry>
|
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</row>
|
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<row>
|
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<entry>128</entry>
|
||||
<entry>E_COMPILE_WARNING</entry>
|
||||
<entry>compile-time warnings (non fatal errors)</entry>
|
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<entry>PHP 4 only</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>256</entry>
|
||||
<entry>E_USER_ERROR</entry>
|
||||
<entry>user-generated error message</entry>
|
||||
<entry>PHP 4 only</entry>
|
||||
</row>
|
||||
<row>
|
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<entry>512</entry>
|
||||
<entry>E_USER_WARNING</entry>
|
||||
<entry>user-generated warning message</entry>
|
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<entry>PHP 4 only</entry>
|
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</row>
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||||
<row>
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<entry>1024</entry>
|
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<entry>E_USER_NOTICE </entry>
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<entry>user-generated notice message</entry>
|
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<entry>PHP 4 only</entry>
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</row>
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<row>
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<entry></entry>
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<entry>E_ALL</entry>
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<entry>all of the above, as supported</entry>
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<entry></entry>
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</row>
|
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</tbody>
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</tgroup>
|
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</table>
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</para>
|
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|
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<para>
|
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The above values (either numerical or symbolic) are used to build
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up a bitmask that specifies which errors to report. You can use the
|
||||
<link linkend="language.operators.bitwise">bitwise operators</link>
|
||||
to combine these values or mask out certain types of errors. Note
|
||||
that only '|', '~', '!', and '&' will be understood within
|
||||
<filename>php.ini</filename>, however, and that no bitwise
|
||||
operators will be understood within <filename>php3.ini</filename>.
|
||||
</para>
|
||||
<para>
|
||||
In PHP 4, the default <link
|
||||
linkend="ini.error-reporting">error_reporting</link> setting is
|
||||
<literal>E_ALL & ~E_NOTICE</literal>, meaning to display all errors
|
||||
and warnings which are not E_NOTICE-level. In PHP 3, the default
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||||
setting is <literal>(E_ERROR | E_WARNING | E_PARSE)</literal>,
|
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meaning the same thing. Note, however, that since constants are not
|
||||
supported in PHP 3's <filename>php3.ini</filename>, the <link
|
||||
linkend="ini.error-reporting">error_reporting</link> setting there
|
||||
must be numeric; hence, it is <literal>7</literal>.
|
||||
</para>
|
||||
|
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<para>
|
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The initial setting can be changed in the ini file with the <link
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||||
linkend="ini.error-reporting">error_reporting</link> directive, in
|
||||
your Apache <filename>httpd.conf</filename> file with the
|
||||
php_error_reporting (php3_error_reporting for PHP 3) directive, and
|
||||
lastly it may be set at runtime within a script by using the
|
||||
<function>error_reporting</function> function.
|
||||
</para>
|
||||
|
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<warning>
|
||||
<para>
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||||
When upgrading code or servers from PHP 3 to PHP 4 you should
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check these settings and calls to
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||||
<function>error_reporting</function> or you might disable
|
||||
reporting the new error types, especially E_COMPILE_ERROR. This
|
||||
may lead to empty documents without any feedback of what happened
|
||||
or where to look for the problem.
|
||||
</para>
|
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</warning>
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||||
|
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<para>
|
||||
All <link linkend="language.expressions">PHP expressions</link> can
|
||||
also be called with the "@" prefix, which turns off error reporting
|
||||
for that particular expression. If an error occurred during such
|
||||
an expression and the <link
|
||||
linkend="ini.track-errors">track_errors</link> feature is enabled,
|
||||
you can find the error message in the global variable
|
||||
$php_errormsg.
|
||||
</para>
|
||||
|
||||
<warning>
|
||||
<para>
|
||||
Currently the <link linkend="language.operators.errorcontrol">@
|
||||
error-control operator</link> prefix will even disable error
|
||||
reporting for critical errors that will terminate script
|
||||
execution. Among other things, this means that if you use <link
|
||||
linkend="language.operators.errorcontrol">@</link> to suppress
|
||||
errors from a certain function and either it isn't available or
|
||||
has been mistyped, the script will die right there with no
|
||||
indication as to why.
|
||||
</para>
|
||||
</warning>
|
||||
|
||||
<para>
|
||||
Below we can see an example of using the error handling capabilities in
|
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PHP. We define a error handling function which logs the information into
|
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a file (using an XML format), and e-mails the developer in case a critical
|
||||
error in the logic happens.
|
||||
<example>
|
||||
<title>Using error handling in a script</title>
|
||||
<programlisting role="php">
|
||||
<?php
|
||||
// we will do our own error handling
|
||||
error_reporting(0);
|
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|
||||
// user defined error handling function
|
||||
function userErrorHandler ($errno, $errmsg, $filename, $linenum, $vars) {
|
||||
// timestamp for the error entry
|
||||
$dt = date("Y-m-d H:i:s (T)");
|
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|
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// define an assoc array of error string
|
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// in reality the only entries we should
|
||||
// consider are 2,8,256,512 and 1024
|
||||
$errortype = array (
|
||||
1 => "Error",
|
||||
2 => "Warning",
|
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4 => "Parsing Error",
|
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8 => "Notice",
|
||||
16 => "Core Error",
|
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32 => "Core Warning",
|
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64 => "Compile Error",
|
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128 => "Compile Warning",
|
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256 => "User Error",
|
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512 => "User Warning",
|
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1024=> "User Notice"
|
||||
);
|
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// set of errors for which a var trace will be saved
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$user_errors = array(E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE);
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|
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$err = "<errorentry>\n";
|
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$err .= "\t<datetime>".$dt."</datetime>\n";
|
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$err .= "\t<errornum>".$errno."</errnumber>\n";
|
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$err .= "\t<errortype>".$errortype[$errno]."</errortype>\n";
|
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$err .= "\t<errormsg>".$errmsg."</errormsg>\n";
|
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$err .= "\t<scriptname>".$filename."</scriptname>\n";
|
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$err .= "\t<scriptlinenum>".$linenum."</scriptlinenum>\n";
|
||||
|
||||
if (in_array($errno, $user_errors))
|
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$err .= "\t<vartrace>".wddx_serialize_value($vars,"Variables")."</vartrace>\n";
|
||||
$err .= "</errorentry>\n\n";
|
||||
|
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// for testing
|
||||
// echo $err;
|
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|
||||
// save to the error log, and e-mail me if there is a critical user error
|
||||
error_log($err, 3, "/usr/local/php4/error.log");
|
||||
if ($errno == E_USER_ERROR)
|
||||
mail("phpdev@mydomain.com","Critical User Error",$err);
|
||||
}
|
||||
|
||||
|
||||
function distance ($vect1, $vect2) {
|
||||
if (!is_array($vect1) || !is_array($vect2)) {
|
||||
trigger_error("Incorrect parameters, arrays expected", E_USER_ERROR);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
if (count($vect1) != count($vect2)) {
|
||||
trigger_error("Vectors need to be of the same size", E_USER_ERROR);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
for ($i=0; $i<count($vect1); $i++) {
|
||||
$c1 = $vect1[$i]; $c2 = $vect2[$i];
|
||||
$d = 0.0;
|
||||
if (!is_numeric($c1)) {
|
||||
trigger_error("Coordinate $i in vector 1 is not a number, using zero",
|
||||
E_USER_WARNING);
|
||||
$c1 = 0.0;
|
||||
}
|
||||
if (!is_numeric($c2)) {
|
||||
trigger_error("Coordinate $i in vector 2 is not a number, using zero",
|
||||
E_USER_WARNING);
|
||||
$c2 = 0.0;
|
||||
}
|
||||
$d += $c2*$c2 - $c1*$c1;
|
||||
}
|
||||
return sqrt($d);
|
||||
}
|
||||
|
||||
$old_error_handler = set_error_handler("userErrorHandler");
|
||||
|
||||
// undefined constant, generates a warning
|
||||
$t = I_AM_NOT_DEFINED;
|
||||
|
||||
// define some "vectors"
|
||||
$a = array(2,3,"foo");
|
||||
$b = array(5.5, 4.3, -1.6);
|
||||
$c = array (1,-3);
|
||||
|
||||
// generate a user error
|
||||
$t1 = distance($c,$b)."\n";
|
||||
|
||||
// generate another user error
|
||||
$t2 = distance($b,"i am not an array")."\n";
|
||||
|
||||
// generate a warning
|
||||
$t3 = distance($a,$b)."\n";
|
||||
|
||||
?>
|
||||
</programlisting>
|
||||
</example>
|
||||
This is just a simple example showing how to use the
|
||||
<link linkend="ref.errorfunc">Error Handling and Logging
|
||||
functions</link>.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
See also <function>error_reporting</function>,
|
||||
<function>error_log</function>,
|
||||
<function>set_error_handler</function>,
|
||||
<function>restore_error_handler</function>,
|
||||
<function>trigger_error</function>,
|
||||
<function>user_error</function>
|
||||
</para>
|
||||
|
||||
</chapter>
|
||||
|
||||
<!-- Keep this comment at the end of the file
|
||||
Local variables:
|
||||
mode: sgml
|
||||
sgml-omittag:t
|
||||
sgml-shorttag:t
|
||||
sgml-minimize-attributes:nil
|
||||
sgml-always-quote-attributes:t
|
||||
sgml-indent-step:1
|
||||
sgml-indent-data:t
|
||||
sgml-parent-document:nil
|
||||
sgml-default-dtd-file:"../../manual.ced"
|
||||
sgml-exposed-tags:nil
|
||||
sgml-local-catalogs:nil
|
||||
sgml-local-ecat-files:nil
|
||||
End:
|
||||
-->
|
||||
125
features/http-auth.xml
Normal file
125
features/http-auth.xml
Normal file
|
|
@ -0,0 +1,125 @@
|
|||
<chapter id="features.http-auth">
|
||||
<title>HTTP authentication with PHP</title>
|
||||
|
||||
<simpara>
|
||||
The HTTP Authentication hooks in PHP are only available when it is
|
||||
running as an Apache module and is hence not available in the CGI version.
|
||||
In an Apache module PHP script, it is possible to use the
|
||||
<function>Header</function> function to send an "Authentication Required"
|
||||
message to the client browser causing it to pop up a Username/Password
|
||||
input window. Once the user has filled in a username and a password,
|
||||
the URL containing the PHP script will be called again with the variables,
|
||||
$PHP_AUTH_USER, $PHP_AUTH_PW and $PHP_AUTH_TYPE set to the user
|
||||
name, password and authentication type respectively. Only "Basic"
|
||||
authentication is supported at this point. See the <function>Header</function>
|
||||
function for more information.</simpara>
|
||||
|
||||
<para>
|
||||
An example script fragment which would force client authentication
|
||||
on a page would be the following:
|
||||
|
||||
<example>
|
||||
<title>HTTP Authentication example</title>
|
||||
<programlisting role="php">
|
||||
<?php
|
||||
if(!isset($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>";
|
||||
}
|
||||
?>
|
||||
</programlisting>
|
||||
</example></para>
|
||||
|
||||
<para>
|
||||
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.</para>
|
||||
|
||||
<para>
|
||||
Watch out for buggy Internet Explorer browsers out there. They
|
||||
seem very picky about the order of the headers. Sending the
|
||||
<emphasis>WWW-Authenticate</emphasis> header before the
|
||||
<errorcode>HTTP/1.0 401</errorcode> header seems to do the trick
|
||||
for now.</para>
|
||||
|
||||
<simpara>
|
||||
In order to prevent someone from writing a script which reveals
|
||||
the password for a page that was authenticated through a
|
||||
traditional external mechanism, the PHP_AUTH variables will not be
|
||||
set if external authentication is enabled for that particular
|
||||
page. In this case, the $REMOTE_USER variable can be used to
|
||||
identify the externally-authenticated user.</simpara>
|
||||
|
||||
<simpara>
|
||||
Note, however, that the above does not prevent someone who
|
||||
controls a non-authenticated URL from stealing passwords from
|
||||
authenticated URLs on the same server.</simpara>
|
||||
<simpara>
|
||||
Both Netscape and Internet Explorer will clear the local browser
|
||||
window's authentication cache for the realm upon receiving a
|
||||
server response of 401. This can effectively "log out" a user,
|
||||
forcing them to re-enter their username and password. Some people
|
||||
use this to "time out" logins, or provide a "log-out" button.</simpara>
|
||||
<simpara></simpara>
|
||||
<example>
|
||||
<title>HTTP Authentication example forcing a new name/password</title>
|
||||
<programlisting role="php">
|
||||
<?php
|
||||
function authenticate() {
|
||||
Header( "WWW-authenticate: basic realm=\"Test Authentication System\"");
|
||||
Header( "HTTP/1.0 401 Unauthorized");
|
||||
echo "You must enter a valid login ID and password to access this resource\n";
|
||||
exit;
|
||||
}
|
||||
|
||||
if(!isset($PHP_AUTH_USER) || ($SeenBefore == 1 && !strcmp($OldAuth, $PHP_AUTH_USER)) ) {
|
||||
authenticate();
|
||||
}
|
||||
else {
|
||||
echo "Welcome: $PHP_AUTH_USER<BR>";
|
||||
echo "Old: $OldAuth";
|
||||
echo "<FORM ACTION=\"$PHP_SELF\" METHOD=POST>\n";
|
||||
echo "<INPUT TYPE=HIDDEN NAME=\"SeenBefore\" VALUE=\"1\">\n";
|
||||
echo "<INPUT TYPE=HIDDEN NAME=\"OldAuth\" VALUE=\"$PHP_AUTH_USER\">\n";
|
||||
echo "<INPUT TYPE=Submit VALUE=\"Re Authenticate\">\n";
|
||||
echo "</FORM>\n";
|
||||
|
||||
}
|
||||
?>
|
||||
</programlisting>
|
||||
</example>
|
||||
<simpara>
|
||||
This behavior is not required by the HTTP Basic authentication
|
||||
standard, so you should never depend on this. Testing with Lynx
|
||||
has shown that Lynx does not clear the authentication credentials
|
||||
with a 401 server response, so pressing back and then forward
|
||||
again will open the resource (as long as the credential
|
||||
requirements haven't changed).</simpara>
|
||||
<simpara>
|
||||
Also note that this does not work using Microsoft's IIS server and
|
||||
the CGI version of PHP due to a limitation of IIS.</simpara>
|
||||
|
||||
</chapter>
|
||||
|
||||
<!-- Keep this comment at the end of the file
|
||||
Local variables:
|
||||
mode: sgml
|
||||
sgml-omittag:t
|
||||
sgml-shorttag:t
|
||||
sgml-minimize-attributes:nil
|
||||
sgml-always-quote-attributes:t
|
||||
sgml-indent-step:1
|
||||
sgml-indent-data:t
|
||||
sgml-parent-document:nil
|
||||
sgml-default-dtd-file:"../manual.ced"
|
||||
sgml-exposed-tags:nil
|
||||
sgml-local-catalogs:nil
|
||||
sgml-local-ecat-files:nil
|
||||
End:
|
||||
-->
|
||||
59
features/images.xml
Normal file
59
features/images.xml
Normal file
|
|
@ -0,0 +1,59 @@
|
|||
<chapter id="features.images">
|
||||
<title>Creating and manipulating images</title>
|
||||
|
||||
<simpara>
|
||||
PHP is not limited to creating just HTML output. It can also be
|
||||
used to create and manipulate image files in a variety of different
|
||||
image formats, including gif, png, jpg, wbmp, and xpm. Even more
|
||||
convenient, php can output image streams directly to a browser. You
|
||||
will need to compile PHP with the GD library of image functions for
|
||||
this to work. GD and PHP may also require other libraries, depending
|
||||
on which image formats you want to work with. GD stopped supporting
|
||||
Gif images in version 1.6.
|
||||
</simpara>
|
||||
|
||||
<para>
|
||||
<example>
|
||||
<title>PNG creation with PHP</title>
|
||||
<programlisting role="php">
|
||||
<?php
|
||||
Header("Content-type: image/png");
|
||||
$string=implode($argv," ");
|
||||
$im = imageCreateFromPng("images/button1.png");
|
||||
$orange = ImageColorAllocate($im, 220, 210, 60);
|
||||
$px = (imagesx($im)-7.5*strlen($string))/2;
|
||||
ImageString($im,3,$px,9,$string,$orange);
|
||||
ImagePng($im);
|
||||
ImageDestroy($im);
|
||||
?>
|
||||
</programlisting>
|
||||
</example>
|
||||
|
||||
This example would be called from a page with a tag like: <img
|
||||
src="button.php?text"> The above button.php script
|
||||
then takes this "text" string an overlays it on top of a
|
||||
base image which in this case is "images/button1.png"
|
||||
and outputs the resulting image. This is a very convenient way to
|
||||
avoid having to draw new button images every time you want to
|
||||
change the text of a button. With this method they are
|
||||
dynamically generated.
|
||||
</para>
|
||||
|
||||
</chapter>
|
||||
|
||||
<!-- Keep this comment at the end of the file
|
||||
Local variables:
|
||||
mode: sgml
|
||||
sgml-omittag:t
|
||||
sgml-shorttag:t
|
||||
sgml-minimize-attributes:nil
|
||||
sgml-always-quote-attributes:t
|
||||
sgml-indent-step:1
|
||||
sgml-indent-data:t
|
||||
sgml-parent-document:nil
|
||||
sgml-default-dtd-file:"../manual.ced"
|
||||
sgml-exposed-tags:nil
|
||||
sgml-local-catalogs:nil
|
||||
sgml-local-ecat-files:nil
|
||||
End:
|
||||
-->
|
||||
Loading…
Reference in a new issue