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/config/manager/local_file.rs

@@ -1,3 +1,4 @@
+use crate::config::check_hash;
 use crate::config::manager::ConfigManager;
 use crate::error::Error;
 use async_trait::async_trait;
@@ -20,11 +21,17 @@ impl ConfigManager for LocalFileConfigManager {
         Ok(fs::read_to_string(&self.file_path)?)
     }
 
-    async fn save_config(&self, content: &str) -> Result<(), Error> {
+    async fn save_config(&self, content: &str, hash: &str) -> Result<(), Error> {
+        let current_content = self.load_as_str().await?;
+        if !check_hash(&current_content, hash) {
+            return Err(Error::Config(format!(
+                "OPNSense config file changed since loading it! Hash when loading : {hash}"
+            )));
+        }
         Ok(fs::write(&self.file_path, content)?)
     }
 
-    async fn apply_new_config(&self, content: &str) -> Result<(), Error> {
-        self.save_config(content).await
+    async fn apply_new_config(&self, content: &str, hash: &str) -> Result<(), Error> {
+        self.save_config(content, hash).await
     }
 }