What is the best way to download an external file to a server via a program.

Question

I have written a WordPress plugin, and I am trying to find the best way of having the program check for updates on my server, and downloading them automatically at the user's request. This will basically be used to download extra features that I don't want to put into the WordPress repository due them not having the GNU license.

I've coded the program to check for updates, what I am not sure about is the download part.

Should I use file_get_contents() and then fwrite() to write the results to a directory? I'm sure that's a way of doing it, but I am looking for the most cross-server safe way of doing this because the plugin is used by thousands of people on different setups, although they are all PHP, and most of them are PHP5+. I am afraid certain hosts may have some sort of security preventing me from doing this. Would cURL be a better option?

Thank you.

Answer 1

You can use file_put_contents, which is much more efficient than loading everything into memory with file_get_contents and then calling fwrite. The second parameter accepts a stream resource, which you can open with fopen or (if you want to get around allow_url_fopen restrictions, fsockopen).

Therefore, the simplest option that uses only core functions (no curl extension, etc) and works in almost evry configuration is:

• Open a transport stream with fsockopen
• Send the HTTP headers manually with fwrite
• Write the response with file_put_contents

Answer 2

Don't re-invent the wheel! WordPress has an HTTP API for this exact purpose!

Check out the codex for the essentials - http://codex.wordpress.org/HTTP_API

You can also browse the source in wp-includes/class-http.php