How to serve part of a file with Nginx? - nginx

Question

I'm using X-Accel to serve protected content, using X-Accel-Redirect.
Is it possible to serve only a part of the file? for example, bytes range 0-x, or first 5 minutes of a video (my final goal)
It's important to do that on the server-side, so the client will not have access to the rest of the file.
Currently this is how I send the whole file:
X-Accel-Cache-Control: no-store, no-cache, must-revalidate
Pragma: no-cache
Content-Type: application/octet-stream
Content-Length: {file_size}
Content-Disposition: attachment; filename="myfile.mp4"
Accept-Ranges: bytes
X-Accel-Buffering: yes
X-Accel-Redirect: /protected/myfile.mp4
Nginx conf:
location /protected {
internal;
alias /dir/of/protected/files/;
if_modified_since off;
output_buffers 2 1m;
open_file_cache max=50000 inactive=10m;
open_file_cache_valid 15m;
open_file_cache_min_uses 1;
open_file_cache_errors off;
}

Answer 1

The massive hack would be to use nginx to proxy to itself with a Range header that would limit the request to a range of bytes
something like this (not tested so this probably wont work, but the idea should work):
{
... snip config ...
server {
listen 80 default_server;
listen [::]:80 default_server;
root /html;
index index.html;
location / {
proxy_pass http://localhost/content;
add_header Range btyes=0,100000;
}
location /content {
try_files $uri $uri/ =404;
}
}
}

Answer 2

I haven't tested Slice and X-Accel together. If each file can have a different limit defined by the backend you might configure Slice in the location and send the limit with the X-Accel-Redirect URL as below:
X-Accel-Cache-Control: no-store, no-cache, must-revalidate
Pragma: no-cache
Content-Type: application/octet-stream
Content-Length: {file_size}
Content-Disposition: attachment; filename="myfile.mp4"
Accept-Ranges: bytes
X-Accel-Buffering: yes
X-Accel-Redirect: /protected/myfile.mp4?s=0&e=$PHP_VAR
Nginx.conf
location /protected {
slice; # enable slicing
slice_start_arg s;
slice_end_arg e;
internal;
alias /dir/of/protected/files/;
if_modified_since off;
output_buffers 2 1m;
open_file_cache max=50000 inactive=10m;
open_file_cache_valid 15m;
open_file_cache_min_uses 1;
open_file_cache_errors off;
}
A global file limit
You would need to redirect the original request including the Slice parameters to truncate the file being served.
Nginx conf:
location /sample {
slice; # enable slicing
slice_start_arg s;
slice_end_arg e;
internal;
alias /dir/of/protected/files/;
if_modified_since off;
output_buffers 2 1m;
open_file_cache max=50000 inactive=10m;
open_file_cache_valid 15m;
open_file_cache_min_uses 1;
open_file_cache_errors off;
}
location /protected {
rewrite ^ /sample&s=0&e=1024; # replace for the desired file limit in bytes
}
If the rewrite directive above doesn't work, I suggest the following option using proxy_pass.
location /protected {
set $file_limit 1024 # replace for the desired file limit in bytes
set $delimiter "";
if ($is_args) {
set $delimiter "&";
}
set $args $args${delimiter}s=0&e=$file_limit;
proxy_pass $scheme://127.0.0.1/sample;
}