68 lines
1.7 KiB
Markdown
68 lines
1.7 KiB
Markdown
Image Proxy
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===========
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To prevent mixed content warnings on SSL pages served from your RSS reader you might want to use an assets proxy.
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Images url will be rewritten to be downloaded through the proxy.
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Example:
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```html
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<img src="http://example.org/image.png"/>
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```
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Can be rewritten like that:
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```html
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<img src="http://myproxy.example.org/?url=http%3A%2F%2Fexample.org%2Fimage.png"/>
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```
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Currently this feature is only compatible with images.
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There is several open source SSL image proxy available like [Camo](https://github.com/atmos/camo).
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You can also write your own proxy.
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Usage
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-----
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There two different ways to use this feature, define a proxy url or a callback.
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### Define a proxy url
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A proxy url must be defined with a placeholder `%s`.
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The placeholder will be replaced by the image source url encoded (RFC 3986).
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In PHP, the url can be decoded with the function `rawurldecode()`.
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```php
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$config = new Config;
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$config->setFilterImageProxyUrl('http://myproxy.example.org/?url=%s');
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```
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Will rewrite the image source like that:
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```html
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<img src="http://myproxy.example.org/?url=http%3A%2F%2Fexample.org%2Fimage.png"/>
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```
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### Define a callback
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Your callback will be called each time an image url need to be rewritten.
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The first argument is the original image url and your function must returns the new image url.
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Here an example if your proxy need a shared secret key:
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```php
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$config = new Config;
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$config->setFilterImageProxyCallback(function ($image_url) {
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$key = hash_hmac('sha1', $image_url, 'secret');
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return 'https://mypublicproxy/'.$key.'/'.rawurlencode($image_url);
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});
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```
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Will generate an image url like that:
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```html
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<img src="https://mypublicproxy/4924964043f3119b3cf2b07b1922d491bcc20092/http%3A%2F%2Ffoo%2Fimage.png"/>
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```
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