PHP Trying to get property of non-object nodeValue

Question

I'm trying to scan all URL (i.e., from http://0.0.0.1 to http://255.255.255.255) and fetch all Titles and Description, and store them in database. I know this is the wrong method, but i'm unable to find better solution. The following code is executed as Cron Job every 5 minutes.

scan.php

#!/usr/bin/php
<?php
error_reporting(E_ALL);
$db_host = "localhost";
$db_username = "root";
$db_password = "*****"; //Connection works fine, hidden for security purpose
$db_name = "lab";
$conn = new mysqli($db_host, $db_username, $db_password, $db_name);
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
function file_get_contents_curl($url)
{
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT ,0); 
    curl_setopt($ch, CURLOPT_TIMEOUT, 10);

    $data = curl_exec($ch);
    curl_close($ch);

    return $data;
}
$sql="SELECT wid FROM websites";
$result=$conn->query($sql);
$num_rows=$result->num_rows;
$nrs=4228250625-$num_rows; //255*255*255*255, going in reverse order
$url_4=$nrs%255;
$nrs=$nrs/255;
$url_3=$nrs%255;
$nrs=$nrs/255;
$url_2=$nrs%255;
$nrs=$nrs/255;
$url_1=$nrs%255;
for($i=1;$i<=5;$i++){
    $url=$url_1.".".$url_2.".".$url_3.".".($url_4-$i);
    try{
    $html = file_get_contents_curl("http://".$url);
    $doc = new DOMDocument();
    @$doc->loadHTML($html);
    $nodes = $doc->getElementsByTagName('title');

    //get and display what you need:
    $title = 'Undefined';
    try {
        if($nodes){
            $title = $nodes->item(0)->nodeValue; //#45 This is where error lies
        }
    }
    catch (Exception $e) {
    }
    $description='';

    $metas = $doc->getElementsByTagName('meta');

    for ($i = 0; $i < $metas->length; $i++)
    {
        $meta = $metas->item($i);
        if($meta->getAttribute('name') == 'description')
            $description = $meta->getAttribute('content');
    }
    $wtime=time();
    $sql="INSERT INTO websites (`url`,`title`,`description`,`wtime`) VALUES ('$url','$title','$description','$wtime')";
    mysqli_query($conn,$sql);
    }
    catch(Exception $e){

    }
}

?>

I'm getting the following error in log file:

[17-Nov-2016 06:22:09 Etc/GMT] PHP Notice:  Trying to get property of non-object in /home/roboca6g/public_html/lab/scan.php on line 48
[17-Nov-2016 06:22:10 Etc/GMT] PHP Notice:  Trying to get property of non-object in /home/roboca6g/public_html/lab/scan.php on line 48
[17-Nov-2016 06:22:11 Etc/GMT] PHP Notice:  Trying to get property of non-object in /home/roboca6g/public_html/lab/scan.php on line 48

Please help me solve this issue, and also if possible, suggest better method to perform similar task.

@wuno I removed the loop and tried `var_dump($doc);`, it returned some output. But when I added the loop back, it gave me 500 Error. Now I cant get it back to work. — Manikiran, Nov 17 '16 at 06:59
If it returned an output then its because it is working. Sounds like you are just not parsing the data correctly. Please see my answer. You need to parse it as a string. — wuno, Nov 17 '16 at 07:03
I'm getting this error now `[17-Nov-2016 07:06:37 Etc/GMT] PHP Parse error: syntax error, unexpected end of file in /home/roboca6g/public_html/lab/scan.php on line 91` — Manikiran, Nov 17 '16 at 07:07
Sorry, i forgot to remove for statement. Its giving out now. `object(DOMDocument)#3 (34) { ["doctype"]=> NULL ["implementation"]=> string(22) "(object value omitted)" ["documentElement"]=> ...` — Manikiran, Nov 17 '16 at 07:11
See? Length is `0`, you don't have `` element. That's why `items(0)` returns NULL — u_mulder, Nov 17 '16 at 07:18
I guess, most of urls wont have title, because those urls dont even exist. — Manikiran, Nov 17 '16 at 07:19
So check length of `$nodes` before using `->items(0)->nodeValue` — u_mulder, Nov 17 '16 at 07:23
http://stackoverflow.com/a/34280920/2218253 and this http://stackoverflow.com/a/24815016/2218253 — wuno, Nov 17 '16 at 07:28
@u_mulder Its taking lot of time to perform curl, can you guys help me limit the time. I added timeout in 10 seconds, not working. — Manikiran, Nov 17 '16 at 07:33
@wuno, sorry couldn't tag two users, please help me limit the time — Manikiran, Nov 17 '16 at 07:33
I am sorry man. I do not understand why I cant read tonight. — wuno, Nov 17 '16 at 07:36

mariusag · Answer 1 · 2019-06-11T11:29:22.590

3

Based on @winston86 answer:

if(is_object($nodes ->item(0))) {
$title = $nodes->item(0)->nodeValue; 
}

Working in my case.

edited Jun 11 '19 at 11:29

answered Jun 11 '19 at 10:33

mariusag

66
6

score 1 · Answer 2 · answered Nov 17 '16 at 06:50

1

Try to check is actually an object the element you working with. Try:

if(is_object($nodes)){
   //do your stuff
}

answered Nov 17 '16 at 06:50

winston86

159
1
8

Sorry i'm unable to verify if your answer works, 'cause i'm getting a 500 error. – Manikiran Nov 17 '16 at 06:58

PHP Trying to get property of non-object nodeValue

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