feat(opnsense-config): dnsmasq dhcp static mappings (#130)

Co-authored-by: Jean-Gabriel Gill-Couture <jeangabriel.gc@gmail.com>
Co-authored-by: Ian Letourneau <ian@noma.to>
Reviewed-on: #130
Reviewed-by: Ian Letourneau <ian@noma.to>
Co-authored-by: Jean-Gabriel Gill-Couture <jg@nationtech.io>
Co-committed-by: Jean-Gabriel Gill-Couture <jg@nationtech.io>

opnsense-config/src/modules/dhcp.rs

@@ -1,4 +1,4 @@
-#[derive(Debug)]
+#[derive(Debug, PartialEq)]
 pub enum DhcpError {
     InvalidMacAddress(String),
     InvalidIpAddress(String),

opnsense-config/src/modules/dns.rs

@@ -1,10 +1,10 @@
 use opnsense_config_xml::{Host, OPNsense};
 
-pub struct DnsConfig<'a> {
+pub struct UnboundDnsConfig<'a> {
     opnsense: &'a mut OPNsense,
 }
 
-impl<'a> DnsConfig<'a> {
+impl<'a> UnboundDnsConfig<'a> {
     pub fn new(opnsense: &'a mut OPNsense) -> Self {
         Self { opnsense }
     }

opnsense-config/src/modules/dnsmasq.rs

@@ -1,9 +1,12 @@
 // dnsmasq.rs
 use crate::modules::dhcp::DhcpError;
-use log::{debug, info};
+use log::{debug, info, warn};
+use opnsense_config_xml::dnsmasq::{DhcpRange, DnsMasq, DnsmasqHost}; // Assuming DhcpRange is defined in opnsense_config_xml::dnsmasq
 use opnsense_config_xml::{MaybeString, StaticMap};
+use std::collections::HashSet;
 use std::net::Ipv4Addr;
 use std::sync::Arc;
+use uuid::Uuid;
 
 use opnsense_config_xml::OPNsense;
 
@@ -25,74 +28,167 @@ impl<'a> DhcpConfigDnsMasq<'a> {
         }
     }
 
-    /// Removes a static mapping by its MAC address.
-    /// Static mappings are stored in the <dhcpd> section of the config, shared with the ISC module.
-    pub fn remove_static_mapping(&mut self, mac: &str) {
-        let lan_dhcpd = self.get_lan_dhcpd();
-        lan_dhcpd
-            .staticmaps
-            .retain(|static_entry| static_entry.mac != mac);
+    /// Removes a MAC address from a static mapping.
+    /// If the mapping has no other MAC addresses associated with it, the entire host entry is removed.
+    pub fn remove_static_mapping(&mut self, mac_to_remove: &str) {
+        let dnsmasq = self.get_dnsmasq();
+
+        // Update hwaddr fields for hosts that contain the MAC, removing it from the comma-separated list.
+        for host in dnsmasq.hosts.iter_mut() {
+            let mac = host.hwaddr.content_string();
+            let original_macs: Vec<&str> = mac.split(',').collect();
+            if original_macs
+                .iter()
+                .any(|m| m.eq_ignore_ascii_case(mac_to_remove))
+            {
+                let updated_macs: Vec<&str> = original_macs
+                    .into_iter()
+                    .filter(|m| !m.eq_ignore_ascii_case(mac_to_remove))
+                    .collect();
+                host.hwaddr = updated_macs.join(",").into();
+            }
+        }
+
+        // Remove any host entries that no longer have any MAC addresses.
+        dnsmasq
+            .hosts
+            .retain(|host_entry| !host_entry.hwaddr.content_string().is_empty());
     }
 
-    /// Retrieves a mutable reference to the LAN interface's DHCP configuration.
-    /// This is located in the shared <dhcpd> section of the config.
-    fn get_lan_dhcpd(&mut self) -> &mut opnsense_config_xml::DhcpInterface {
-        &mut self
-            .opnsense
-            .dhcpd
-            .elements
-            .iter_mut()
-            .find(|(name, _config)| name == "lan")
-            .expect("Interface lan should have dhcpd activated")
-            .1
+    /// Retrieves a mutable reference to the DnsMasq configuration.
+    /// This is located in the <dnsmasq> section of the OPNsense config.
+    fn get_dnsmasq(&mut self) -> &mut DnsMasq {
+        self.opnsense
+            .dnsmasq
+            .as_mut()
+            .expect("Dnsmasq config must be initialized")
     }
 
-    /// Adds a new static DHCP mapping.
-    /// Validates the MAC address and checks for existing mappings to prevent conflicts.
+    /// Adds or updates a static DHCP mapping.
+    ///
+    /// This function implements specific logic to handle existing entries:
+    /// - If no host exists for the given IP or hostname, a new entry is created.
+    /// - If exactly one host exists for the IP and/or hostname, the new MAC is appended to it.
+    /// - It will error if the IP and hostname exist but point to two different host entries,
+    ///   as this represents an unresolvable conflict.
+    /// - It will also error if multiple entries are found for the IP or hostname, indicating an
+    ///   ambiguous state.
     pub fn add_static_mapping(
         &mut self,
-        mac: &str,
-        ipaddr: Ipv4Addr,
+        mac: &Vec<String>,
+        ipaddr: &Ipv4Addr,
         hostname: &str,
     ) -> Result<(), DhcpError> {
-        let mac = mac.to_string();
-        let hostname = hostname.to_string();
-        let lan_dhcpd = self.get_lan_dhcpd();
-        let existing_mappings: &mut Vec<StaticMap> = &mut lan_dhcpd.staticmaps;
+        let mut hostname_split = hostname.split(".");
+        let hostname = hostname_split.next().expect("hostname cannot be empty");
+        let domain_name = hostname_split.collect::<Vec<&str>>().join(".");
 
-        if !Self::is_valid_mac(&mac) {
-            return Err(DhcpError::InvalidMacAddress(mac));
+        if let Some(m) = mac.iter().find(|m| !Self::is_valid_mac(m)) {
+            return Err(DhcpError::InvalidMacAddress(m.to_string()));
         }
 
-        // TODO: Validate that the IP address is within a configured DHCP range.
+        let ip_str = ipaddr.to_string();
+        let hosts = &mut self.get_dnsmasq().hosts;
 
-        if existing_mappings
+        let ip_indices: Vec<usize> = hosts
             .iter()
-            .any(|m| m.ipaddr == ipaddr.to_string() && m.mac == mac)
-        {
-            info!("Mapping already exists for {} [{}], skipping", ipaddr, mac);
-            return Ok(());
-        }
+            .enumerate()
+            .filter(|(_, h)| h.ip.content_string() == ip_str)
+            .map(|(i, _)| i)
+            .collect();
 
-        if existing_mappings
+        let hostname_indices: Vec<usize> = hosts
             .iter()
-            .any(|m| m.ipaddr == ipaddr.to_string())
+            .enumerate()
+            .filter(|(_, h)| h.host == hostname)
+            .map(|(i, _)| i)
+            .collect();
+
+        let ip_set: HashSet<usize> = ip_indices.iter().cloned().collect();
+        let hostname_set: HashSet<usize> = hostname_indices.iter().cloned().collect();
+
+        if !ip_indices.is_empty()
+            && !hostname_indices.is_empty()
+            && ip_set.intersection(&hostname_set).count() == 0
         {
-            return Err(DhcpError::IpAddressAlreadyMapped(ipaddr.to_string()));
+            return Err(DhcpError::Configuration(format!(
+                "Configuration conflict: IP {} and hostname '{}' exist, but in different static host entries.",
+                ipaddr, hostname
+            )));
         }
 
-        if existing_mappings.iter().any(|m| m.mac == mac) {
-            return Err(DhcpError::MacAddressAlreadyMapped(mac));
+        let mut all_indices: Vec<&usize> = ip_set.union(&hostname_set).collect();
+        all_indices.sort();
+
+        let mac_list = mac.join(",");
+
+        match all_indices.len() {
+            0 => {
+                info!(
+                    "Creating new static host for {} ({}) with MAC {}",
+                    hostname, ipaddr, mac_list
+                );
+                let new_host = DnsmasqHost {
+                    uuid: Uuid::new_v4().to_string(),
+                    host: hostname.to_string(),
+                    ip: ip_str.into(),
+                    hwaddr: mac_list.into(),
+                    local: MaybeString::from("1"),
+                    ignore: Some(0),
+                    domain: domain_name.into(),
+                    ..Default::default()
+                };
+                hosts.push(new_host);
+            }
+            1 => {
+                let host_index = *all_indices[0];
+                let host_to_modify = &mut hosts[host_index];
+                let host_to_modify_ip = host_to_modify.ip.content_string();
+                if host_to_modify_ip != ip_str {
+                    warn!(
+                        "Hostname '{}' already exists with a different IP ({}). Setting new IP {ip_str}. Appending MAC {}.",
+                        hostname, host_to_modify_ip, mac_list
+                    );
+                    host_to_modify.ip.content = Some(ip_str);
+                } else if host_to_modify.host != hostname {
+                    warn!(
+                        "IP {} already exists with a different hostname ('{}'). Setting hostname to {hostname}. Appending MAC {}.",
+                        ipaddr, host_to_modify.host, mac_list
+                    );
+                    host_to_modify.host = hostname.to_string();
+                }
+
+                for single_mac in mac.iter() {
+                    if !host_to_modify
+                        .hwaddr
+                        .content_string()
+                        .split(',')
+                        .any(|m| m.eq_ignore_ascii_case(single_mac))
+                    {
+                        info!(
+                            "Appending MAC {} to existing static host for {} ({})",
+                            single_mac, host_to_modify.host, host_to_modify_ip
+                        );
+                        let mut updated_macs = host_to_modify.hwaddr.content_string().to_string();
+                        updated_macs.push(',');
+                        updated_macs.push_str(single_mac);
+                        host_to_modify.hwaddr.content = updated_macs.into();
+                    } else {
+                        debug!(
+                        "MAC {} already present in static host entry for {} ({}). No changes made.",
+                        single_mac, host_to_modify.host, host_to_modify_ip
+                    );
+                    }
+                }
+            }
+            _ => {
+                return Err(DhcpError::Configuration(format!(
+                    "Configuration conflict: Found multiple host entries matching IP {} and/or hostname '{}'. Cannot resolve automatically.",
+                    ipaddr, hostname
+                )));
+            }
         }
 
-        let static_map = StaticMap {
-            mac,
-            ipaddr: ipaddr.to_string(),
-            hostname: hostname,
-            ..Default::default()
-        };
-
-        existing_mappings.push(static_map);
         Ok(())
     }
 
@@ -110,13 +206,20 @@ impl<'a> DhcpConfigDnsMasq<'a> {
     /// Retrieves the list of current static mappings by shelling out to `configctl`.
     /// This provides the real-time state from the running system.
     pub async fn get_static_mappings(&self) -> Result<Vec<StaticMap>, Error> {
+        // Note: This command is for the 'dhcpd' service. If dnsmasq uses a different command
+        // or key, this will need to be adjusted.
         let list_static_output = self
             .opnsense_shell
             .exec("configctl dhcpd list static")
             .await?;
 
-        let value: serde_json::Value = serde_json::from_str(&list_static_output)
-            .unwrap_or_else(|_| panic!("Got invalid json from configctl {list_static_output}"));
+        let value: serde_json::Value = serde_json::from_str(&list_static_output).map_err(|e| {
+            Error::Command(format!(
+                "Got invalid json from configctl {list_static_output} : {e}"
+            ))
+        })?;
+
+        // The JSON output key might be 'dhcpd' even when dnsmasq is the backend.
         let static_maps = value["dhcpd"]
             .as_array()
             .ok_or(Error::Command(format!(
@@ -135,6 +238,36 @@ impl<'a> DhcpConfigDnsMasq<'a> {
         Ok(static_maps)
     }
 
+    pub async fn set_dhcp_range(&mut self, start: &str, end: &str) -> Result<(), DhcpError> {
+        let dnsmasq = self.get_dnsmasq();
+        let ranges = &mut dnsmasq.dhcp_ranges;
+
+        // Assuming DnsMasq has dhcp_ranges: Vec<DhcpRange>
+        // Find existing range for "lan" interface
+        if let Some(range) = ranges
+            .iter_mut()
+            .find(|r| r.interface == Some("lan".to_string()))
+        {
+            // Update existing range
+            range.start_addr = Some(start.to_string());
+            range.end_addr = Some(end.to_string());
+        } else {
+            // Create new range
+            let new_range = DhcpRange {
+                uuid: Some(Uuid::new_v4().to_string()),
+                interface: Some("lan".to_string()),
+                start_addr: Some(start.to_string()),
+                end_addr: Some(end.to_string()),
+                domain_type: Some("range".to_string()),
+                nosync: Some(0),
+                ..Default::default()
+            };
+            ranges.push(new_range);
+        }
+
+        Ok(())
+    }
+
     pub async fn set_pxe_options(
         &self,
         tftp_ip: Option<String>,
@@ -142,9 +275,9 @@ impl<'a> DhcpConfigDnsMasq<'a> {
         efi_filename: String,
         ipxe_filename: String,
     ) -> Result<(), DhcpError> {
-        // As of writing this opnsense does not support negative tags, and the dnsmasq config is a
-        // bit complicated anyways. So we are writing directly a dnsmasq config file to
-        // /usr/local/etc/dnsmasq.conf.d
+        // OPNsense does not support negative tags via its API for dnsmasq, and the required
+        // logic is complex. Therefore, we write a configuration file directly to the
+        // dnsmasq.conf.d directory to achieve the desired PXE boot behavior.
         let tftp_str = tftp_ip.map_or(String::new(), |i| format!(",{i},{i}"));
 
         let config = format!(
@@ -163,7 +296,7 @@ dhcp-boot=tag:efi,tag:!ipxe,{efi_filename}{tftp_str}
 dhcp-boot=tag:ipxe,{ipxe_filename}{tftp_str}
 
 # Provide undionly to legacy bios clients
-dhcp-boot=tag:bios,{bios_filename}{tftp_str}
+dhcp-boot=tag:bios,tag:!ipxe,{bios_filename}{tftp_str}
 "
         );
         info!("Writing configuration file to {DNS_MASQ_PXE_CONFIG_FILE}");
@@ -185,3 +318,302 @@ dhcp-boot=tag:bios,{bios_filename}{tftp_str}
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod test {
+    use crate::config::DummyOPNSenseShell;
+
+    use super::*;
+    use opnsense_config_xml::OPNsense;
+    use std::net::Ipv4Addr;
+    use std::sync::Arc;
+
+    /// Helper function to create a DnsmasqHost with minimal boilerplate.
+    fn create_host(uuid: &str, host: &str, ip: &str, hwaddr: &str) -> DnsmasqHost {
+        DnsmasqHost {
+            uuid: uuid.to_string(),
+            host: host.to_string(),
+            ip: ip.into(),
+            hwaddr: hwaddr.into(),
+            local: MaybeString::from("1"),
+            ignore: Some(0),
+            ..Default::default()
+        }
+    }
+
+    /// Helper to set up the test environment with an initial OPNsense configuration.
+    fn setup_test_env(initial_hosts: Vec<DnsmasqHost>) -> DhcpConfigDnsMasq<'static> {
+        let opnsense_config = Box::leak(Box::new(OPNsense {
+            dnsmasq: Some(DnsMasq {
+                hosts: initial_hosts,
+                ..Default::default()
+            }),
+            ..Default::default()
+        }));
+
+        DhcpConfigDnsMasq::new(opnsense_config, Arc::new(DummyOPNSenseShell {}))
+    }
+
+    #[test]
+    fn test_add_first_static_mapping() {
+        let mut dhcp_config = setup_test_env(vec![]);
+        let ip = Ipv4Addr::new(192, 168, 1, 10);
+        let mac = "00:11:22:33:44:55";
+        let hostname = "new-host";
+
+        dhcp_config
+            .add_static_mapping(&vec![mac.to_string()], &ip, hostname)
+            .unwrap();
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        let host = &hosts[0];
+        assert_eq!(host.host, hostname);
+        assert_eq!(host.ip, ip.to_string().into());
+        assert_eq!(host.hwaddr.content_string(), mac);
+        assert!(Uuid::parse_str(&host.uuid).is_ok());
+    }
+
+    #[test]
+    fn test_hostname_split_into_host_domain() {
+        let mut dhcp_config = setup_test_env(vec![]);
+        let ip = Ipv4Addr::new(192, 168, 1, 10);
+        let mac = "00:11:22:33:44:55";
+        let hostname = "new-host";
+        let domain = "some.domain";
+
+        dhcp_config
+            .add_static_mapping(&vec![mac.to_string()], &ip, &format!("{hostname}.{domain}"))
+            .unwrap();
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        let host = &hosts[0];
+        assert_eq!(host.host, hostname);
+        assert_eq!(host.domain.content_string(), domain);
+        assert_eq!(host.ip, ip.to_string().into());
+        assert_eq!(host.hwaddr.content_string(), mac);
+        assert!(Uuid::parse_str(&host.uuid).is_ok());
+    }
+
+    #[test]
+    fn test_add_mac_to_existing_host_by_ip_and_hostname() {
+        let initial_host = create_host(
+            "uuid-1",
+            "existing-host",
+            "192.168.1.20",
+            "AA:BB:CC:DD:EE:FF",
+        );
+        let mut dhcp_config = setup_test_env(vec![initial_host]);
+        let ip = Ipv4Addr::new(192, 168, 1, 20);
+        let new_mac = "00:11:22:33:44:55";
+        let hostname = "existing-host";
+
+        dhcp_config
+            .add_static_mapping(&vec![new_mac.to_string()], &ip, hostname)
+            .unwrap();
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        let host = &hosts[0];
+        assert_eq!(
+            host.hwaddr.content_string(),
+            "AA:BB:CC:DD:EE:FF,00:11:22:33:44:55"
+        );
+    }
+
+    #[test]
+    fn test_add_mac_to_existing_host_by_ip_only() {
+        let initial_host = create_host(
+            "uuid-1",
+            "existing-host",
+            "192.168.1.20",
+            "AA:BB:CC:DD:EE:FF",
+        );
+        let mut dhcp_config = setup_test_env(vec![initial_host]);
+        let ip = Ipv4Addr::new(192, 168, 1, 20);
+        let new_mac = "00:11:22:33:44:55";
+
+        // Using a different hostname should still find the host by IP and log a warning.
+        let new_hostname = "different-host-name";
+        dhcp_config
+            .add_static_mapping(&vec![new_mac.to_string()], &ip, new_hostname)
+            .unwrap();
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        let host = &hosts[0];
+        assert_eq!(
+            host.hwaddr.content_string(),
+            "AA:BB:CC:DD:EE:FF,00:11:22:33:44:55"
+        );
+        assert_eq!(host.host, new_hostname); // hostname should be updated
+    }
+
+    #[test]
+    fn test_add_mac_to_existing_host_by_hostname_only() {
+        let initial_host = create_host(
+            "uuid-1",
+            "existing-host",
+            "192.168.1.20",
+            "AA:BB:CC:DD:EE:FF",
+        );
+        let mut dhcp_config = setup_test_env(vec![initial_host]);
+        let new_mac = "00:11:22:33:44:55";
+        let hostname = "existing-host";
+
+        // Using a different IP should still find the host by hostname and log a warning.
+        dhcp_config
+            .add_static_mapping(
+                &vec![new_mac.to_string()],
+                &Ipv4Addr::new(192, 168, 1, 99),
+                hostname,
+            )
+            .unwrap();
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        let host = &hosts[0];
+        assert_eq!(
+            host.hwaddr.content_string(),
+            "AA:BB:CC:DD:EE:FF,00:11:22:33:44:55"
+        );
+        assert_eq!(host.ip.content_string(), "192.168.1.99"); // Original IP should be preserved.
+    }
+
+    #[test]
+    fn test_add_duplicate_mac_to_host() {
+        let initial_mac = "AA:BB:CC:DD:EE:FF";
+        let initial_host = create_host("uuid-1", "host-1", "192.168.1.20", initial_mac);
+        let mut dhcp_config = setup_test_env(vec![initial_host]);
+
+        dhcp_config
+            .add_static_mapping(
+                &vec![initial_mac.to_string()],
+                &Ipv4Addr::new(192, 168, 1, 20),
+                "host-1",
+            )
+            .unwrap();
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        assert_eq!(hosts[0].hwaddr.content_string(), initial_mac); // No change, no duplication.
+    }
+
+    #[test]
+    fn test_add_invalid_mac_address() {
+        let mut dhcp_config = setup_test_env(vec![]);
+        let result = dhcp_config.add_static_mapping(
+            &vec!["invalid-mac".to_string()],
+            &Ipv4Addr::new(10, 0, 0, 1),
+            "host",
+        );
+        assert!(matches!(result, Err(DhcpError::InvalidMacAddress(_))));
+    }
+
+    #[test]
+    fn test_error_on_conflicting_ip_and_hostname() {
+        let host_a = create_host("uuid-a", "host-a", "192.168.1.10", "AA:AA:AA:AA:AA:AA");
+        let host_b = create_host("uuid-b", "host-b", "192.168.1.20", "BB:BB:BB:BB:BB:BB");
+        let mut dhcp_config = setup_test_env(vec![host_a, host_b]);
+
+        let result = dhcp_config.add_static_mapping(
+            &vec!["CC:CC:CC:CC:CC:CC".to_string()],
+            &Ipv4Addr::new(192, 168, 1, 10),
+            "host-b",
+        );
+        // This IP belongs to host-a, but the hostname belongs to host-b.
+        assert_eq!(result, Err(DhcpError::Configuration("Configuration conflict: IP 192.168.1.10 and hostname 'host-b' exist, but in different static host entries.".to_string())));
+    }
+
+    #[test]
+    fn test_error_on_multiple_ip_matches() {
+        let host_a = create_host("uuid-a", "host-a", "192.168.1.30", "AA:AA:AA:AA:AA:AA");
+        let host_b = create_host("uuid-b", "host-b", "192.168.1.30", "BB:BB:BB:BB:BB:BB");
+        let mut dhcp_config = setup_test_env(vec![host_a, host_b]);
+
+        // This IP is ambiguous.
+        let result = dhcp_config.add_static_mapping(
+            &vec!["CC:CC:CC:CC:CC:CC".to_string()],
+            &Ipv4Addr::new(192, 168, 1, 30),
+            "new-host",
+        );
+        assert_eq!(result, Err(DhcpError::Configuration("Configuration conflict: Found multiple host entries matching IP 192.168.1.30 and/or hostname 'new-host'. Cannot resolve automatically.".to_string())));
+    }
+
+    #[test]
+    fn test_remove_mac_from_multi_mac_host() {
+        let host = create_host("uuid-1", "host-1", "192.168.1.50", "mac-1,mac-2,mac-3");
+        let mut dhcp_config = setup_test_env(vec![host]);
+
+        dhcp_config.remove_static_mapping("mac-2");
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        assert_eq!(hosts[0].hwaddr.content_string(), "mac-1,mac-3");
+    }
+
+    #[test]
+    fn test_remove_last_mac_from_host() {
+        let host = create_host("uuid-1", "host-1", "192.168.1.50", "mac-1");
+        let mut dhcp_config = setup_test_env(vec![host]);
+
+        dhcp_config.remove_static_mapping("mac-1");
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert!(hosts.is_empty());
+    }
+
+    #[test]
+    fn test_remove_non_existent_mac() {
+        let host = create_host("uuid-1", "host-1", "192.168.1.50", "mac-1,mac-2");
+        let mut dhcp_config = setup_test_env(vec![host.clone()]);
+
+        dhcp_config.remove_static_mapping("mac-nonexistent");
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 1);
+        assert_eq!(hosts[0], host); // The host should be unchanged.
+    }
+
+    #[test]
+    fn test_remove_mac_case_insensitively() {
+        let host = create_host("uuid-1", "host-1", "192.168.1.50", "AA:BB:CC:DD:EE:FF");
+        let mut dhcp_config = setup_test_env(vec![host]);
+
+        dhcp_config.remove_static_mapping("aa:bb:cc:dd:ee:ff");
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert!(hosts.is_empty());
+    }
+
+    #[test]
+    fn test_remove_mac_from_correct_host_only() {
+        let host1 = create_host(
+            "uuid-1",
+            "host-1",
+            "192.168.1.50",
+            "AA:AA:AA:AA:AA:AA,BB:BB:BB:BB:BB:BB",
+        );
+        let host2 = create_host(
+            "uuid-2",
+            "host-2",
+            "192.168.1.51",
+            "CC:CC:CC:CC:CC:CC,DD:DD:DD:DD:DD:DD",
+        );
+        let mut dhcp_config = setup_test_env(vec![host1.clone(), host2.clone()]);
+
+        dhcp_config.remove_static_mapping("AA:AA:AA:AA:AA:AA");
+
+        let hosts = &dhcp_config.opnsense.dnsmasq.as_ref().unwrap().hosts;
+        assert_eq!(hosts.len(), 2);
+        let updated_host1 = hosts.iter().find(|h| h.uuid == "uuid-1").unwrap();
+        let unchanged_host2 = hosts.iter().find(|h| h.uuid == "uuid-2").unwrap();
+
+        assert_eq!(updated_host1.hwaddr.content_string(), "BB:BB:BB:BB:BB:BB");
+        assert_eq!(
+            unchanged_host2.hwaddr.content_string(),
+            "CC:CC:CC:CC:CC:CC,DD:DD:DD:DD:DD:DD"
+        );
+    }
+}