Catching fwrite() / socket errors - php

Question

I am creating a library which is making a socket connection:
public function __construct(Options $options)
{
$this->responseBuffer = new Response();
$this->connection = stream_socket_client($options->fullSocketAddress());
if (!$this->isAlive($this->connection)) {
throw new DeadSocket();
}
stream_set_timeout($this->connection, $this->timeout);
$this->options = $options;
}
Sending the data to the server goes through send() method which looks like this:
public function send(string $xml)
{
try {
fwrite($this->connection, $xml);
} catch (Exception $e) {
$this->options->getLogger()->error(__METHOD__ . '::' . __LINE__ . " fwrite() failed " . $e->getMessage());
return;
}
}
The problem being here that catch doesn't capture PHP notice errors which seem to be the indicator in my case that connection itself is broken.
In case the server error happened, I am getting a <stream:error> (XMPP standard), however if socket broke or some timeout happened like this one, I can't catch it:
[22-May-2019 12:35:07 UTC] PHP Notice: fwrite(): send of 94 bytes failed with errno=110 Connection timed out in .../Socket.php on line 52
At this time I would like to know if error happened so that I can trigger reconnection, however doing any of these didn't seem helpful:
if (!is_resource($this->connection)) $this->reconnect();
if (!$this->connection) $this->reconnect();
As well as checking any of the socket_get_status() properties since socket_get_status($this->connection)['timed_out'] can be true even with alive connection.
Is there a way to catch this notice?
Also is there a way to simulate the behavior so I can reproduce it even when the connection doesn't time out?

Answer 1

You can set just the level by calling error_reporting, like:
error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);
Or, you can set your own error handler, using set_error_handler. You can find an example on the page as well:
<?php
// error handler function
function myErrorHandler($errno, $errstr, $errfile, $errline)
{
if (!(error_reporting() & $errno)) {
// This error code is not included in error_reporting, so let it fall
// through to the standard PHP error handler
return false;
}
switch ($errno) {
case E_USER_ERROR:
echo "<b>My ERROR</b> [$errno] $errstr<br />\n";
echo " Fatal error on line $errline in file $errfile";
echo ", PHP " . PHP_VERSION . " (" . PHP_OS . ")<br />\n";
echo "Aborting...<br />\n";
exit(1);
break;
case E_USER_WARNING:
echo "<b>My WARNING</b> [$errno] $errstr<br />\n";
break;
case E_USER_NOTICE:
echo "<b>My NOTICE</b> [$errno] $errstr<br />\n";
break;
default:
echo "Unknown error type: [$errno] $errstr<br />\n";
break;
}
/* Don't execute PHP internal error handler */
return true;
}
// function to test the error handling
function scale_by_log($vect, $scale)
{
if (!is_numeric($scale) || $scale <= 0) {
trigger_error("log(x) for x <= 0 is undefined, you used: scale = $scale", E_USER_ERROR);
}
if (!is_array($vect)) {
trigger_error("Incorrect input vector, array of values expected", E_USER_WARNING);
return null;
}
$temp = array();
foreach($vect as $pos => $value) {
if (!is_numeric($value)) {
trigger_error("Value at position $pos is not a number, using 0 (zero)", E_USER_NOTICE);
$value = 0;
}
$temp[$pos] = log($scale) * $value;
}
return $temp;
}
// set to the user defined error handler
$old_error_handler = set_error_handler("myErrorHandler");
// trigger some errors, first define a mixed array with a non-numeric item
echo "vector a\n";
$a = array(2, 3, "foo", 5.5, 43.3, 21.11);
print_r($a);
// now generate second array
echo "----\nvector b - a notice (b = log(PI) * a)\n";
/* Value at position $pos is not a number, using 0 (zero) */
$b = scale_by_log($a, M_PI);
print_r($b);
// this is trouble, we pass a string instead of an array
echo "----\nvector c - a warning\n";
/* Incorrect input vector, array of values expected */
$c = scale_by_log("not array", 2.3);
var_dump($c); // NULL
// this is a critical error, log of zero or negative number is undefined
echo "----\nvector d - fatal error\n";
/* log(x) for x <= 0 is undefined, you used: scale = $scale" */
$d = scale_by_log($a, -2.5);
var_dump($d); // Never reached
?>