WAF integration

[ennetech]

it could be interesting to integrate coraza (https://github.com/corazawaf/coraza) directly in fabio?

before starting the implementation I would like some feedback

[nathanejohnson]

This looks very interesting. What did you have in mind?

[ennetech]

• create a global configuration "all request go trough WAF"
• create label "waf" for per-route configuration
• find the best way to load the directives (i am thinking a global rule definition with the coreruleset, but i would like also per-route specific rules)
• if the connection should pass thru waf fabio should run the parser and return an error if an intrusion is detected

Also i am working on a distributed firewall written in golang and i would like to report waf failures to it

[nathanejohnson]

I would love to see a PR around this! I'm not yet familiar with the coraza project, but I might play it with next week when things are slow with the holiday.

[ennetech]

@nathanejohnson #915 this is the bare minimum to get it working