Add cmd module

This module implements basic "ip" commands to add and remove IP addresses
on network interfaces and to bring interfaces up before use.

Author: Techassi

crates/lib-dhcp/src/client/cmd.rs

@@ -0,0 +1,59 @@
+use std::{
+    net::Ipv4Addr,
+    process::{Command, ExitStatus},
+};
+
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum CmdError {
+    #[error("Unexpected exist status: {0}")]
+    UnexpectedStatus(ExitStatus),
+
+    #[error("IO error: {0}")]
+    IoError(#[from] std::io::Error),
+}
+
+pub fn set_interface_up(interface_name: &String) -> Result<(), CmdError> {
+    let status = Command::new("ip")
+        .args(["link", "set"])
+        .args(["dev", interface_name, "up"])
+        .status()?;
+
+    if !status.success() {
+        return Err(CmdError::UnexpectedStatus(status));
+    }
+
+    Ok(())
+}
+
+/// Flushes the IP address of the interface with `interface_name`.
+pub fn flush_ip_address(interface_name: &String) -> Result<(), CmdError> {
+    // ip -4 addr flush dev ${interface}
+    let status = Command::new("ip")
+        .arg("-4")
+        .args(["addr", "flush"])
+        .args(["dev", interface_name])
+        .status()?;
+
+    if !status.success() {
+        return Err(CmdError::UnexpectedStatus(status));
+    }
+
+    Ok(())
+}
+
+/// Adds an IP address to the interface with `interface_name`.
+pub fn add_ip_address(ip_addr: &Ipv4Addr, interface_name: &String) -> Result<(), CmdError> {
+    let status = Command::new("ip")
+        .arg("-4")
+        .args(["addr", "add", &ip_addr.to_string()])
+        .args(["dev", interface_name])
+        .status()?;
+
+    if !status.success() {
+        return Err(CmdError::UnexpectedStatus(status));
+    }
+
+    Ok(())
+}

crates/lib-dhcp/src/client/error.rs

@@ -4,7 +4,7 @@ use network_interface::Error as InterfaceError;
 use thiserror::Error;
 
 use crate::{
-    client::state::DhcpStateError,
+    client::{cmd::CmdError, state::DhcpStateError},
     types::{MessageError, ParseHardwareAddrError},
 };
 
@@ -34,6 +34,9 @@ pub enum ClientError {
     #[error("Message error: {0}")]
     MessageError(#[from] MessageError),
 
+    #[error("Command error: {0}")]
+    CmdError(#[from] CmdError),
+
     #[error("Invalid message format or length: {0}")]
     Invalid(String),
 }

crates/lib-dhcp/src/client/mod.rs

@@ -20,6 +20,7 @@ use crate::{
     utils, TimeoutResult, DHCP_MINIMUM_LEGAL_MAX_MESSAGE_SIZE, DHCP_SERVER_PORT,
 };
 
+mod cmd;
 mod error;
 mod state;