Improve event source IP reporting

[kasparsd]

Feature Request

Determining user's IP reliably is difficult when the web server is behind layers of proxies as the request is made by the intermediary on behalf of the client. Here is how various services pass the origin IP to the server:

• Cloudflare https://developers.cloudflare.com/support/troubleshooting/restoring-visitor-ips/restoring-original-visitor-ips/
• WordPress VIP https://docs.wpvip.com/how-tos/configure-a-reverse-proxy/
• AWS CloudFront https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/example-function-add-true-client-ip-header.html

There is no reliable way for the WP plugin or WP core to detect the client IP so it would be useful to offer a filter for the current logic here:

stream/classes/class-log.php

Lines 45 to 49 in bfc0530

	// Support proxy mode by checking the `X-Forwarded-For` header first.
	$ip_address = wp_stream_filter_input( INPUT_SERVER, 'HTTP_X_FORWARDED_FOR', FILTER_VALIDATE_IP );
	$ip_address = $ip_address ? $ip_address : wp_stream_filter_input( INPUT_SERVER, 'REMOTE_ADDR', FILTER_VALIDATE_IP );
	$this->ip_address = $ip_address;

[kasparsd]

Version 4.0.0 has been tagged https://github.com/xwp/stream/releases/tag/4.0.0 and deployed to WP.org https://plugins.trac.wordpress.org/changeset/3019411/stream