Enable advanced dialing requests both on `Swarm` and via
`NetworkBehaviourAction`. Users can now trigger a dial with a specific
set of addresses, optionally extended via
`NetworkBehaviour::addresses_of_peer`. In addition the whole process is
now modelled in a type safe way via the builder pattern.
Example of a `NetworkBehaviour` requesting a dial to a specific peer
with a set of addresses additionally extended through
`NetworkBehaviour::addresses_of_peer`:
```rust
NetworkBehaviourAction::Dial {
opts: DialOpts::peer_id(peer_id)
.condition(PeerCondition::Always)
.addresses(addresses)
.extend_addresses_through_behaviour()
.build(),
handler,
}
```
Example of a user requesting a dial to an unknown peer with a single
address via `Swarm`:
```rust
swarm1.dial(
DialOpts::unknown_peer_id()
.address(addr2.clone())
.build()
)
```
Concurrently dial address candidates within a single dial attempt.
Main motivation for this feature is to increase success rate on hole punching
(see https://github.com/libp2p/rust-libp2p/issues/1896#issuecomment-885894496
for details). Though, as a nice side effect, as one would expect, it does
improve connection establishment time.
Cleanups and fixes done along the way:
- Merge `pool.rs` and `manager.rs`.
- Instead of manually implementing state machines in `task.rs` use
`async/await`.
- Fix bug where `NetworkBehaviour::inject_connection_closed` is called without a
previous `NetworkBehaviour::inject_connection_established` (see
https://github.com/libp2p/rust-libp2p/issues/2242).
- Return handler to behaviour on incoming connection limit error. Missed in
https://github.com/libp2p/rust-libp2p/issues/2242.
Basic file sharing application with peers either providing or locating
and getting files by name.
While obviously showcasing how to build a basic file sharing
application, the actual goal of this example is **to show how to
integrate rust-libp2p into a larger application**.
Architectural properties
- Clean clonable async/await interface ([`Client`]) to interact with the
network layer.
- Single task driving the network layer, no locks required.
