New function ngx_http_get_forwarded_addr() to look up real client address. On input it takes an original address, string in the X-Forwarded-For format and its length, list of trusted proxies, and a flag indicating to perform the recursive search. On output it returns NGX_OK and the "deepest" valid address in a chain, or NGX_DECLINED. It supports AF_INET and AF_INET6. Additionally, original address and/or proxy may be specified as AF_UNIX.