Hi Tim, On Fri, Feb 21, 2020 at 11:37:42AM +0100, Tim Düsterhus wrote: > Hi List > > I'm currently attempting to extend Proxy Protocol v2 by a new TLV to > send a unique ID for TCP connections, similar to the unique-id-header > for HTTP. > > I'm currently struggling to get the `struct stream` within > `make_proxy_line_v2`. I could find out that I can get the `struct > session` via `remote->owner`, but from there I have no idea how to get a > `struct stream`. By printing the allocations it appears that a stream > should already exist by the time the proxy line is sent.
You will not get back to a stream based on a connection because there may be many streams per connection. A connection will lead you to a mux (H1,H2,FCGI) and from there depending on the mux's protocol and internals you'll have 0 to many streams above. However in many cases you could know the stream that requested the outgoing connection. That's what is used when you see that "remote" thing. In conn_si_send_proxy(), there's a test to see if the the first connection's conn_stream's owner is a stream_interface, and if so it uses si_opposite() to find the other side. From this stream interface you can get the requesting stream using si_strm(). > So questions: > 1. Would it generally work to send a unique ID within the proxy line or > will that cause issues? I'm not seeing any particular issues, however this would require a strict definition of how the unique-id is built. I'm assuming you want to use the same unique-id as the one built per-stream, but the problem is that you'll get many streams over a connection, and that at most one of them will have the same ID as the connection (and possibly even none of them), and the other ones will remain unrelated. In this context one can wonder what's the benefit of building an ID at the stream level to use it at the connection level. Maybe you just need a per-connection unique ID. But in this case we might need a way similar to the existing one to define the format. Or maybe you should just resort to a UUID that is sent only when some option is used ? > 2. How can I grab the `struct stream` from the `struct connection > remote` or more general: How can I get the correct `struct stream` from > within `make_proxy_line_v2`? >From within make_proxy_line_v2() you're too low for this but in conn_si_send_proxy() it's OK. Just be careful about what I mentioned above regarding unicity vs streams. Cheers, Willy
