How to Make Safari Download Files Properly with Laravel

I'm building a file upload/download feature into my SaaS app Sikrt, and after working out the kinks in a prototype version of the feature, to my consternation I discovered that clicking the download link in Safari produced a different outcome than in other browsers.

The expected behavior when downloading, say, a .jpg file is for the file to be saved with the designated name and the .jpg extension. Well, turns out that Safari appends a .html at the end, thus saving the file as filename.jpg.html instead of filename.jpg.

After a little googling I came across this discussion that helped me isolate and fix the problem. The interesting bit here is the curl -I command.

Running this command against my download link, I got the following (in this particular case I'm trying to download an icon file with an .ico extension):

curl -I http://sikrt.test/d/oc6anhsjt

HTTP/1.1 200 OK
Server: nginx/1.15.0
Content-Type: text/html; charset=UTF-8
Connection: keep-alive
Vary: Accept-Encoding
X-Powered-By: PHP/7.2.12
0: Content-Type: application/octet-stream
1: Content-Disposition: attachment; filename="oc6anhsjt.ico"
Cache-Control: no-cache, private
Date: Mon, 03 Jun 2019 02:23:03 GMT
Content-Disposition: attachment; filename=oc6anhsjt.ico
Set-Cookie: XSRF-TOKEN=eyJpdiI6IlVoXC8yOTVtQWRVT3ZuUmVqWitOcWhBPT0iLCJ2YWx1ZSI6InA3aHpSWE5pR0o3cUV5cEdjQXJySE4yVFJsdFVqQk5UOUtyXC9UQTZ2TXRLYlBUYWk1aFJ3UU5hVWk4TE5ibTdYIiwibWFjIjoiODY3ZmQ4ZTU1YzNjODRmODU2ZTgyNDJhN2Q2YjczNzRjY2MyZGIwZDVhMjFhZmMxNDU1NDJlNjZhOGM0NzYyZSJ9; expires=Tue, 04-Jun-2019 02:23:03 GMT; Max-Age=86400; path=/
Set-Cookie: sikrt_session=eyJpdiI6IkpRWjhlUEJvTTltWTBkUGFGa1h5bWc9PSIsInZhbHVlIjoicTdycmQ1U3czSGhoS3BFNER5SGo3bFo4OG1yMFFwRGxWZTdmSmZcL1dPNVdTUmROY1VPMUV2YXRNOW9HK1pUb2oiLCJtYWMiOiIzMjMxYjIwODE4NjVhNGQ3OTRmN2ViZTgxMDRmYTMyOGFkMzA1ZTM3YTNiNzZmMGUxYjc5MjdiYmYwZGQ0MWU1In0%3D; expires=Tue, 04-Jun-2019 02:23:03 GMT; Max-Age=86400; path=/; httponly

The trick to get Safari to download the file with the proper extension is to send the correct headers, in this case Content-Type: application/octet-stream.

Right off the bat you might notice this bit:

0: Content-Type: application/octet-stream
1: Content-Disposition: attachment; filename="oc6anhsjt.ico"

Something looks funky here, and that's because there shouldn't be a 0: in front of the header. Why is that? Because I was passing the headers as an array of strings instead of an associative array. Laravel's documentation doesn't explain how the headers array should be structured. Running the curl command helped me diagnose the issue.

Before

[
    'Content-Type: application/octet-stream',
    ...
]

After

[
    'Content-Type' => 'application/octet-stream',
    ...
]

Following this fix, Safari was able to download the file with the correct extension.

Running curl -I again produced the correct output:

curl -I http://sikrt.test/d/oc6anhsjt

HTTP/1.1 200 OK
Server: nginx/1.15.0
Content-Type: application/octet-stream
Content-Length: 610
Connection: keep-alive
X-Powered-By: PHP/7.2.12
Content-Disposition: attachment; filename=oc6anhsjt.ico
Cache-Control: no-cache, private
Date: Mon, 03 Jun 2019 02:27:05 GMT
Set-Cookie: XSRF-TOKEN=eyJpdiI6InIySU1uOEJcL0hDMFdyaUk3Q3BIKzB3PT0iLCJ2YWx1ZSI6IjVFaG9Iem1zeXY5UVdPeCtWdFkzXC95cVcwU2Njd0ZyMHFaMXd6bDQrUnJYNkJtRUV5THk4UlFPcjRXaTMzd2F0IiwibWFjIjoiZDA1MWU1YzEzYzVlMGE0OWZjMTIxNzdhOTNmMGU1YTY1MzRkMWYzMWU5M2RmYWZjMDVlZWU5YmUzYTU3ZjNhNCJ9; expires=Tue, 04-Jun-2019 02:27:05 GMT; Max-Age=86400; path=/
Set-Cookie: sikrt_session=eyJpdiI6IkxGT0lUZytKSXFuUWltOXZqSzAySHc9PSIsInZhbHVlIjoiazRDUHlUUHNEMTI3cGtkRktGVVFEMmo1QXRhc1MyVGE1OEdCNE9SZHJPWXRLbVowSXJLZDRcL3QwYTg4MVZFbFwvIiwibWFjIjoiNWU1NDllNDJiNTBiZDFiYzY0NThlNThjYTg4NmM0OGEyNzFmYmYwZjg1ODdhYzQzZjJjMzJhY2MyOWI0NThjOCJ9; expires=Tue, 04-Jun-2019 02:27:05 GMT; Max-Age=86400; path=/; httponly

The piece of code that handles the download looks something like this:

use League\Flysystem\Filesystem;
use League\Flysystem\Memory\MemoryAdapter;

// ...

$filesystem = new Filesystem(new MemoryAdapter()); // keep the file in memory
$filesystem->write('file', $filedata);

return response()->streamDownload(function () use ($filesystem) {
    echo $filesystem->read('file');
}, $filename, [
    'Content-Type' => 'application/octet-stream',
    'Content-Length' => $filesystem->getSize('file'),
    'Content-Disposition' => "attachment; filename=\"{$filename}\"",
]);