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Core PHP function dns_get_record is undefined #1042

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wojtekn opened this issue Feb 20, 2024 · 4 comments · May be fixed by #1067
Open

Core PHP function dns_get_record is undefined #1042

wojtekn opened this issue Feb 20, 2024 · 4 comments · May be fixed by #1067
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@bgrgicak
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[Feature] PHP.wasm [Type] Bug An existing feature does not function as intended
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Zero Crashes

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@wojtekn
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wojtekn commented Feb 20, 2024

The dns_get_record() function, which is a core PHP function, is undefined in PHP-WASM. It results in throwing fatal errors when it's used in code.

Steps to reproduce:

  1. Open https://playground.wordpress.net/ and enable network access
  2. Navigate to Dashboard -> Plugins
  3. Click Add New Plugin
  4. Locate the Jetpack plugin, click Install Now
  5. When the plugin is installed, click Activate

Notice the fatal error:

Fatal error: Uncaught Error: Call to undefined function Automattic\Jetpack\Status\dns_get_record() in /wordpress/wp-content/plugins/jetpack/jetpack_vendor/automattic/jetpack-status/src/class-host.php:145
@wojtekn
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wojtekn commented Feb 20, 2024

Possible clue:

https://forum.aapanel.com/d/12374-help-how-fix-call-to-undefined-function-dns-get-record/7

@adamziel adamziel added [Type] Bug An existing feature does not function as intended [Feature] PHP.wasm labels Feb 20, 2024
@sejas
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sejas commented Feb 20, 2024

Here is a quick link to trigger the same error:
https://playground.wordpress.net/?networking=yes&plugin=jetpack&url=/wp-admin/plugins.php

@p-jackson
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Looking at the PHP source for dns_get_record it looks like the function is only defined if HAVE_DNS_SEARCH_FUNC is defined.

This forum post implies that the dns_get_record() function depends on functions from libc. I suspect if those functions aren't available then HAVE_DNS_SEARCH_FUNC won't be defined.

So it may come down to what's available when PHP is being compiled to wasm. Usually there's a ./configure script which sets up constants like HAVE_DNS_SEARCH_FUNC based on which functions are available on the current system. Are all these libc functions available to the web assembly target we're compiling to?

adamziel added a commit that referenced this issue Feb 27, 2024
@adamziel
Polyfill dns_check_record(), dns_get_record(), and dns_get_mx()
2b10aa2 
Closes #1042 by
polyfilling the dns_* functions that are missing in the WebAssembly
build of PHP. In the PHP source code, these functions are included
conditionally when the HAVE_DNS_SEARCH_FUNC constant is true, which it
isn't in the Emscripten build.

The polyfills return either `false` or an empty array and do not
actually perform any DNS checks.

In Node.js, we could support actual dns checks. Let's leave that for a
subsequent iteration. In the browser, there isn't much we can do.

 ## Remaining work

Rebuild the browser versions of PHP

 ## Testing instructions

Confirm the CI checks pass

CC @p-jackson @sejas @wojtekn
@adamziel adamziel linked a pull request Feb 27, 2024 that will close this issue
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@jeherve jeherve mentioned this issue Feb 28, 2024
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@bgrgicak
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https://playground.wordpress.net/#{%22landingPage%22:%20%22/%22,%22steps%22:%20[{%22step%22:%20%22writeFile%22,%22path%22:%20%22/wordpress/wp-content/mu-plugins/error.php%22,%22data%22:%20%22%3C?php%20$result%20=%20dns_get_record('php.net');%20error_log(print_r($result,%20true));%22}]}

@bgrgicak bgrgicak assigned bgrgicak and unassigned bgrgicak Apr 18, 2024
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Labels
[Feature] PHP.wasm [Type] Bug An existing feature does not function as intended
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Zero Crashes
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Successfully merging a pull request may close this issue.

Polyfill dns_check_record(), dns_get_record(), and dns_get_mx() WordPress/wordpress-playground
5 participants
@adamziel @wojtekn @sejas @bgrgicak @p-jackson