Edit report at https://bugs.php.net/bug.php?id=81516&edit=1
ID: 81516
Updated by: requinix@php.net
Reported by: roland at nextendweb dot com
Summary: Curl used with CURLOPT_WRITEFUNCTION rarely corrupts
the response
-Status: Open
+Status: Feedback
Type: Bug
-Package: Streams related
+Package: cURL related
PHP Version: 7.4.24
Block user comment: N
Private report: N
New Comment:
Are you sure this is related to CURLOPT_WRITEFUNCTION? Can you confirm that stream_body is not being
called for some chunk in the middle of the response? Would be nice if you could modify cURL.php to
not need the write function, but with a casual glance at the code I don't think it would be
easy.
How about varying the buffer size to some fraction/multiple of 1160, like 580 or 2320?
And, of course, are there any relevant differences in configuration between the servers? How about
with the files or paths being written to?
No offense but this doesn't really sound like a bug in PHP, or even in cURL itself, but rather
some weird hiccup or fault with those specific servers.
Previous Comments:
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[2021-10-08 17:52:08] roland at nextendweb dot com
Description:
------------
This issue happened through WordPress update system during plugin update. Our update url points to
our private server and serving a zip file. We had tens of thousands updates for this very same file
and there were only 2 sites which had this issue, so I think it is not related how we serve the
file.
The error is md5_mismatch: The checksum of the file (4a3b968a44c585a2883e687d61c251fb) does not
match the expected checksum value (231732259d67fe83ed6fc02d7ad9be57).
I started to debug this issue, I had the original zip file and the corrupted one which WordPress
downloaded. I diffed the files and at some point it seems like some part is missing in the corrupted
file. Like the stream lost a piece from the buffer. And it happens all the time on those servers.
https://i.imgur.com/Nx0SKeK.png
Curl transport handled this download, so I head over to /wp-includes/Requests/Transport/cURL.php: https://github.com/WordPress/WordPress/blob/master/wp-includes/Requests/Transport/cURL.php
And when I removed CURLOPT_BUFFERSIZE or changed anything else (Requests::BUFFER_SIZE+1,
Requests::BUFFER_SIZE-1), download_url function started to behave as it should and the file was not
corrupted anymore.
<?php
curl_setopt($this->handle, CURLOPT_BUFFERSIZE, Requests::BUFFER_SIZE);
Requests::BUFFER_SIZE value is 1160 in WordPress.
Exactly one 1160 bytes block is missing in the middle of the file, which is the value of
Requests::BUFFER_SIZE.
https://i.imgur.com/KoWkzco.png
Both site had the following configuration:
WordPress 5.8.1
PHP 7.4.24
Curl 7.71.0
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Edit this bug report at https://bugs.php.net/bug.php?id=81516&edit=1