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Re: [MirageOS-devel] Thoughts on the STACKV4 interface


(my only caveat being that removing STACK will require updating many many code 
samples etc, so this might take a while to merge. but i am generally in favour 
of making the apis more uniform, and of having a good high-level api.)

On 25 Nov 2014, at 10:41, Nicolas Ojeda Bar <no263@xxxxxxxxxxxxxxx> wrote:

> Hi list,
> TL;DR- With the addition of IPv6 the interface V1.STACKV4 (renamed
> NETSTACK) looks like an overgrown garden of weed and grass. I propose
> (see below) to completely eliminate this interface and to shift its
> role to the existing Udp & Tcp signatures/implementations.
> Right now STACKV4 performs two roles:
> 1) Keeps track of open ports for Tcp & Udp
> 2) Connects together the whole stack of TCP/UDP over IP, ARP over
> Remarks:
> - 1) this can be done independently for Tcp and Udp and there doesn't
> seem to be a problem keeping the `port -> callback` table in those
> modules directly.
> - 2) boils down to calling `Ethif.input`, `Ipv{4,6}.input` with
> arguments specifying the callbacks for each protocol.  With the
> current signatures one needs to have all the callback functions "at
> once".  It is not possible to register, say, the `tcp` callback
> independently of the `udp` callback or the `ipv4` callback
> independently of the `ipv6` one.  But this is easily solved by making
> the implementations keep a table `protocol -> callback` and exposing a
> function in the signatures to register such a callback.
> - STACKV4 is neither a good low-level nor a good high-level
> abstraction to the network stack.  We should let the existing
> ETHIF/IP/TCP/UDP provide a low-level interface and start thinking how
> to make a good high-level interface (maybe in the style of `launchd`
> or `systemd`) to all network services (and maybe other Mirage
> services?) that hides these modules.
> If we make the above changes then there is no more a raison d'etre for
> STACKV4 and we can eliminate it altogether.  The current unikernels
> that depend on stackv4 will instead depend on a subset of {udp,tcp} x
> {ipv4,ipv6}. Instead of having a DIRECT/SOCKET network stack we would
> have DIRECT/SOCKET UDP & TCP implementations.
> Thoughts ?
> Cheers,
> Nicolas
> _______________________________________________
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