Supporting multiple network interfaces

[PetrichorIT]

This PR changes:

• adds NodeIdentifiers to decouple node addresses and node identities
• adds IpSubnets to model different subnets (subnets are not yet supported, see #132 for progress)
• adds 1:n mappings between names and IpAddr in dns.rs
• decouple dns registration from dns lookups (lookups of nonexistent names will no longer return a newly allocated address)
• integrales reverse dns lookups into ToIpAddr trait

relates to #132

[mcches]

Apologies for the delay in review. I have this queued up for tomorrow morning (08/15).

[PetrichorIT]

So in the spirit of breaking things, this PR fully supports multiple IP subnets, thus multiple bound addresses.

Changes

• Nodes are identified by a NodeIdentifier, thus they always have a human-readable name
• All nodes in the simulation are now connected through a list of subnets provided to Builder::ip_subnets
  • The default subnets are (IPv4 192.168.0.0/16 + IPv6 fe80::/64)
  • Each node is assigned an address in every subnet. Addresses can be specified with NodeBuilder::with_addr or are automatically assigned in the node creation process
• Node creation can now be managed using the NodeBuilder API
  • Sim::client and Sim::host are still supported, but may be removed
  • Sim::client and Sim::host no longer support impl ToIpAddr as input, only impl AsRef<str> is supported, since every node needs are name (provided input is only used as a name, not longer as an addr)
• DNS changes
  • lookup will no longer be used to register nodes (consider it read-only from now on)
  • Dns::register can be used to register new nodes in the DNS resolution
  • since every node has a name, every node is represented in the DNS struct
  • Reverse lookups now return a node identifier, instead of a string
  • removed trait ToIpAddr, since all queries may return multiple IP address
  • the public API was already using trait ToIpAddrs, so no changes there
  • internally for_pairs was replaced by for_connected_pairs, since only IPs in the same subnet are connected
  • trait ToSocketAddrs can now return multiple addrs
• Topology
  • Only IPs in the same subnet are connected in the topology
  • endpoints keeps track of all addresses in one subnet, for easier node creation (maybe broadcast in the future?)
• Host specific
  • Hosts are now bound to multiple addrs
  • net::tcp and net::udp bind / connect to appropriate addresses
• removed IpVersion and Builder::ip_version
• removed *_many APIs

Open questions

Builder API

The node builder API is somewhat cumbersome, when creating very simple nodes. Notably build_client or build_host seems very verbose.

sim.node("my-simple-node").build_client(async { ... });

We could implement the API in such a way to allow these statements,

sim.client("my-simple-node").build(async { ... });
sim.host("my-simple-host").build(async { ... });

but that would use up the fn names Sim::client and Sim::host. Alternatively we could keep the original Sim::client / Sim::host as simple aliases to the fully qualified form.

[mcches]

I've not gotten the time to review this, many applogies. Another issue just came up that can provide further motivation for prioritizing this work.

See #153

[progwriter]

Hi folks, any update here?

This looks like a super useful feature for modeling systems in networking, where multi-interfaces are a must. Would be great to see this available in turmoil!

[mcches]

Hi folks, any update here?

This looks like a super useful feature for modeling systems in networking, where multi-interfaces are a must. Would be great to see this available in turmoil!

Thanks for checking in. This is low priority at the moment. I've got a decent refactor underway for the net modules and after that is in I can pick up contributing to this or guiding the changes.

Can you please elaborate on your use cases/requirements so that we take them into consideration?

[progwriter]

Can you please elaborate on your use cases/requirements so that we take them into consideration?

At a high level, doing some testing of a network routing protocol. Since the protocol uses a mix of tcp + udp, was hoping to use turmoil to remove networking non-determinism and enable contained testing + fault injection.

Being able to treat routers as having multiple interfaces is pretty important (for link-local and loopback-to-loopback communication)

[mcches]

Closing due to inactivity and because we need to refactor some core things for this to work.