Crate netsim[−][src]
netsim
is a crate for simulating networks for the sake of testing network-oriented Rust
code. You can use it to run Rust functions in network-isolated containers, and assemble
virtual networks for these functions to communicate over.
Spawning threads into isolated network namespaces
Network namespaces are a linux feature which can provide a thread or process with its own view
of the system's network interfaces and routing table. This crate's spawn
module provides the
new_namespace
function for spawning threads into their own network namespaces. In this
demonstration we list the visible network interfaces using the
get_if_addrs
crate.
extern crate netsim; extern crate get_if_addrs; extern crate tokio_core; use netsim::spawn; use tokio_core::reactor::Core; use get_if_addrs::get_if_addrs; // First, check that there is more than one network interface. This will generally be true // since there will at least be the loopback interface. let interfaces = get_if_addrs().unwrap(); assert!(interfaces.len() > 0); // Now check how many network interfaces we can see inside a fresh network namespace. There // should be zero. let spawn_complete = spawn::new_namespace(|| { get_if_addrs().unwrap() }); let mut core = Core::new().unwrap(); let interfaces = core.run(spawn_complete).unwrap(); assert!(interfaces.is_empty());
This demonstrates how to launch a thread - perhaps running an automated test - into a sandboxed environment. However an environment with no network interfaces is pretty useless...
Creating virtual interfaces
We can create virtual IP and Ethernet interfaces using the types in the iface
module. For
example, IpIface
lets you create a new IP (TUN) interface and implements futures::{Stream, Sink}
so that you can read/write raw packets to it.
extern crate netsim; extern crate tokio_core; extern crate futures; use std::net::Ipv4Addr; use tokio_core::reactor::Core; use futures::{Future, Stream}; use netsim::iface::IpIfaceBuilder; use netsim::spawn; let mut core = Core::new().unwrap(); let handle = core.handle(); // Create a network interface named "netsim" // Note: This will likely fail with "permission denied" unless we run it in a fresh network // environment let iface = { IpIfaceBuilder::new() .name("netsim") .ipv4_addr(Ipv4Addr::new(192, 168, 0, 24), 24) .build(&handle) .unwrap() }; // Read the first `Ipv4Packet` sent from the interface. let packet = core.run({ iface .into_future() .map_err(|(e, _)| e) .map(|(packet_opt, _)| packet_opt.unwrap()) }).unwrap();
However, for simply testing network code, you don't need to create interfaces manually like this.
Sandboxing network code
Rather than performing the above two steps individually, you can use the spawn::ipv4_tree
function along with the node
module to set up a namespace with an IPv4 interface for you.
extern crate netsim; extern crate tokio_core; extern crate futures; use std::net::UdpSocket; use tokio_core::reactor::Core; use futures::{Future, Stream}; use netsim::{spawn, node, Network, Ipv4Range}; use netsim::wire::Ipv4Payload; // Create an event loop and a network to bind devices to. let mut core = Core::new().unwrap(); let network = Network::new(&core.handle()); let handle = network.handle(); // Spawn a network with a single node - a machine with an IPv4 interface in the 10.0.0.0/8 // range, running the given callback. let (spawn_complete, ipv4_plug) = spawn::ipv4_tree( &handle, Ipv4Range::local_subnet_10(), node::ipv4::machine(|ipv4_addr| { // Send a packet out the interface let socket = UdpSocket::bind("0.0.0.0:0").unwrap(); socket.send_to(b"hello world", "10.1.2.3:4567").unwrap(); }), ); let (packet_tx, packet_rx) = ipv4_plug.split(); // Inspect the packet sent out the interface. core.run({ packet_rx .into_future() .map_err(|(v, _)| v) .map(|(packet_opt, _)| { let packet = packet_opt.unwrap(); match packet.payload() { Ipv4Payload::Udp(udp) => { assert_eq!(&udp.payload()[..], &b"hello world"[..]); }, _ => panic!("unexpected payload"), } }) }).unwrap()
Simulating networks of communicating nodes
Using the spawn
and node
modules you can set up a bunch of nodes connected over a virtual
network.
extern crate tokio_core; extern crate future_utils; extern crate netsim; use std::net::UdpSocket; use tokio_core::reactor::Core; use netsim::{spawn, node, Network, Ipv4Range}; // Create an event loop and a network to bind devices to. let mut core = Core::new().unwrap(); let network = Network::new(&core.handle()); let handle = network.handle(); let (tx, rx) = std::sync::mpsc::channel(); // Create a machine which will receive a UDP packet and return its contents let receiver_node = node::ipv4::machine(move |ipv4_addr| { let socket = UdpSocket::bind(("0.0.0.0", 1234)).unwrap(); /// Tell the sending node our IP address tx.send(ipv4_addr).unwrap(); let mut buffer = [0; 1024]; let (n, _sender_addr) = socket.recv_from(&mut buffer).unwrap(); buffer[..n].to_owned() }); // Create the machine which will send the UDP packet let sender_node = node::ipv4::machine(move |_ipv4_addr| { let receiver_ip = rx.recv().unwrap(); let socket = UdpSocket::bind("0.0.0.0:0").unwrap(); socket.send_to(b"hello world", (receiver_ip, 1234)).unwrap(); }); // Connect the sending and receiving nodes via a router let router_node = node::ipv4::router((receiver_node, sender_node)); // Run the network with the router as the top-most node. `_plug` could be used send/receive // packets from/to outside the network let (spawn_complete, _plug) = spawn::ipv4_tree(&handle, Ipv4Range::global(), router_node); // Drive the network on the event loop and get the data returned by the receiving node. let (received, ()) = core.run(spawn_complete).unwrap(); assert_eq!(&received[..], b"hello world");
All the rest
It's possible to set up more complicated (non-hierarchical) network topologies, ethernet
networks, namespaces with multiple interfaces etc. by directly using the primitives in the
device
module. Have an explore of the API, and if anything needs clarification or could be
better designed then let us know on the bug tracker :)
Modules
device |
The types in this module allow you to construct arbitrary network topologies. Have a look at
the |
iface |
Contains utilities for creating virtual TUN/TAP network interfaces. |
node |
This module is for use with the |
spawn |
The |
wire |
Types for ethernet/IP packets. |
Structs
IpLog |
A sink for IP packets which writes the packets to a pcap file. |
Ipv4Range |
A range of IPv4 addresses with a common prefix |
Ipv4Route |
Represents an IPv4 route. |
Ipv6Range |
A range of IPv6 addresses with a common prefix |
Ipv6Route |
Represents an IPv6 route. |
Network |
A |
NetworkHandle |
A handle to a |
SpawnComplete |
A handle to the spawned network-isolated thread. Implements |
Enums
AddRouteError |
Errors returned by |
IpRangeParseError |
Errors returned by |
Traits
Ipv4AddrExt |
Extension methods for IPv4 addresses |
Ipv6AddrExt |
Extension methods for IPv6 addresses |