Poor handling of HTTP error codes

[krizhanovsky]

Use configuration from https://github.com/tempesta-tech/tempesta/wiki/Web-security#dns-rebinding and send a request like:

$ strace -s512 wget http://192.168.100.4/

(no Host header). In the strace output you'll see

HTTP/1.1 502 Bad Gateway\r\n
Date: Mon, 05 Feb 2018 10:09:34 GMT\r\n
Content-Length: 0\r\n
Connection: keep-alive\r\n\r\n

, no Server header, which is very wished. Moreover, Tempesta FW doesn't log anything in dmesg - all HTTP error responses must be logged with net ratelimiting.