Added a way to enable host-only networking through tart using --net-host (#32)

* Added a way to enable host-only networking through tart using SOFTNET_NET_TYPE=host

* Removed env variable and moved to Enum instead of str

* Fixed defaults & restricted publicity of host

* Fixed usage of NetType

lib/host.rs

@@ -1,3 +1,4 @@
+use clap::ArgEnum;
 use anyhow::{anyhow, Context, Result};
 use std::net::Ipv4Addr;
 use std::os::unix::io::{AsRawFd, RawFd};
@@ -8,6 +9,18 @@ use vmnet::mode::Mode;
 use vmnet::parameters::{Parameter, ParameterKind};
 use vmnet::{Events, Options};
 
+#[derive(ArgEnum, Clone, Debug)]
+pub enum NetType {
+    /// Shared network
+    ///
+    /// Uses NAT-translation to give guests access to the global network
+    Nat,
+    /// Host network
+    ///
+    /// Guests will be able to talk only to the host without access to global network
+    Host,
+}
+
 pub struct Host {
     interface: vmnet::Interface,
     new_packets_rx: UnixDatagram,
@@ -18,10 +31,13 @@ pub struct Host {
 }
 
 impl Host {
-    pub fn new() -> Result<Host> {
-        // Initialize a vmnet.framework NAT interface with isolation enabled
+    pub fn new(vm_net_type: NetType) -> Result<Host> {
+        // Initialize a vmnet.framework NAT or Host interface with isolation enabled
         let mut interface = vmnet::Interface::new(
-            Mode::Shared(Default::default()),
+            match vm_net_type {
+                NetType::Nat => Mode::Shared(Default::default()),
+                NetType::Host => Mode::Host(Default::default()),
+            },
             Options {
                 enable_isolation: Some(true),
                 ..Default::default()

lib/mod.rs

@@ -1,5 +1,6 @@
 mod dhcp_snooper;
 mod host;
+pub use host::NetType;
 mod poller;
 pub mod proxy;
 mod vm;

lib/proxy/mod.rs

@@ -4,6 +4,7 @@ mod vm;
 
 use crate::dhcp_snooper::DhcpSnooper;
 use crate::host::Host;
+use crate::host::NetType;
 use crate::poller::Poller;
 use crate::vm::VM;
 use anyhow::Result;
@@ -22,9 +23,9 @@ pub struct Proxy {
 }
 
 impl Proxy {
-    pub fn new(vm_fd: RawFd, vm_mac_address: MacAddress) -> Result<Proxy> {
+    pub fn new(vm_fd: RawFd, vm_mac_address: MacAddress, vm_net_type: NetType) -> Result<Proxy> {
         let vm = VM::new(vm_fd)?;
-        let host = Host::new()?;
+        let host = Host::new(vm_net_type)?;
         let poller = Poller::new(vm.as_raw_fd(), host.as_raw_fd())?;
 
         Ok(Proxy {

src/main.rs

@@ -2,6 +2,7 @@ use anyhow::{anyhow, Context};
 use clap::Parser;
 use nix::sys::signal::{signal, SigHandler, Signal};
 use privdrop::PrivDrop;
+use softnet::NetType;
 use softnet::proxy::Proxy;
 use std::borrow::Cow;
 use std::env;
@@ -28,6 +29,9 @@ struct Args {
     #[clap(long, help = "MAC address to enforce for the VM")]
     vm_mac_address: mac_address::MacAddress,
 
+    #[clap(long, arg_enum, help = "type of network to use for the VM", default_value_t=NetType::Nat)]
+    vm_net_type: NetType,
+
     #[clap(
         long,
         help = "set bootpd(8) lease time to this value (in seconds) before starting the VM",
@@ -140,7 +144,7 @@ fn try_main() -> anyhow::Result<()> {
     set_bootpd_lease_time(args.bootpd_lease_time);
 
     // Initialize the proxy while still having the root privileges
-    let mut proxy = Proxy::new(args.vm_fd as RawFd, args.vm_mac_address)
+    let mut proxy = Proxy::new(args.vm_fd as RawFd, args.vm_mac_address, args.vm_net_type)
         .context("failed to initialize proxy")?;
 
     // Drop effective privileges to the user