Now a new structure ngx_proxy_protocol_t holds these fields. This allows
to add more PROXY protocol fields in the future without modifying the
connection structure.
Previously, unix sockets were treated as AF_INET ones, and this may
result in buffer overread on Linux, where unbound unix sockets have
2-byte addresses.
Note that it is not correct to use just sun_path as a binary representation
for unix sockets. This will result in an empty string for unbound unix
sockets, and thus behaviour of limit_req and limit_conn will change when
switching from $remote_addr to $binary_remote_addr. As such, normal text
representation is used.
Reported by Stephan Dollberg.
The stream session status is one of the following:
200 - normal completion
403 - access forbidden
500 - internal server error
502 - bad gateway
503 - limit conn
