Allow sendmail to be configurable

This reverts a previous change which removed the sendmail to be configurable.
We now set the config to be read-only, and omit all read-only values from being stored during a save action from the admin interface.

Signed-off-by: BlackDex <black.dex@gmail.com>

.env.template

@@ -534,6 +534,8 @@
 
 # Whether to send mail via the `sendmail` command
 # USE_SENDMAIL=false
+# Which sendmail command to use. The one found in the $PATH is used if not specified.
+# SENDMAIL_COMMAND="/path/to/sendmail"
 
 ## Defaults for SSL is "Plain" and "Login" and nothing for Non-SSL connections.
 ## Possible values: ["Plain", "Login", "Xoauth2"].

src/api/admin.rs

@@ -747,7 +747,7 @@ fn get_diagnostics_http(code: u16, _token: AdminToken) -> EmptyResult {
 #[post("/config", format = "application/json", data = "<data>")]
 fn post_config(data: Json<ConfigBuilder>, _token: AdminToken) -> EmptyResult {
     let data: ConfigBuilder = data.into_inner();
-    if let Err(e) = CONFIG.update_config(data) {
+    if let Err(e) = CONFIG.update_config(data, true) {
         err!(format!("Unable to save config: {e:?}"))
     }
     Ok(())

src/config.rs

@@ -116,6 +116,14 @@ macro_rules! make_config {
                 serde_json::from_str(&config_str).map_err(Into::into)
             }
 
+            fn clear_non_editable(&mut self) {
+                $($(
+                    if !$editable {
+                        self.$name = None;
+                    }
+                )+)+
+            }
+
             /// Merges the values of both builders into a new builder.
             /// If both have the same element, `other` wins.
             fn merge(&self, other: &Self, show_overrides: bool, overrides: &mut Vec<String>) -> Self {
@@ -678,6 +686,8 @@ make_config! {
         _enable_smtp:                  bool,   true,   def,     true;
         /// Use Sendmail |> Whether to send mail via the `sendmail` command
         use_sendmail:                  bool,   true,   def,     false;
+        /// Sendmail Command |> Which sendmail command to use. The one found in the $PATH is used if not specified.
+        sendmail_command:              String, false,  option;
         /// Host
         smtp_host:                     String, true,   option;
         /// DEPRECATED smtp_ssl |> DEPRECATED - Please use SMTP_SECURITY
@@ -890,12 +900,16 @@ fn validate_config(cfg: &ConfigItems) -> Result<(), Error> {
         }
 
         if cfg.use_sendmail {
-            let command = format!("sendmail{EXE_SUFFIX}");
+            let command = cfg.sendmail_command.clone().unwrap_or_else(|| format!("sendmail{EXE_SUFFIX}"));
 
-            // Check if we can find the sendmail command to execute
+            let mut path = std::path::PathBuf::from(&command);
-            let Ok(path) = which::which(&command) else {
+            // Check if we can find the sendmail command to execute when no absolute path is given
+            if !path.is_absolute() {
+                let Ok(which_path) = which::which(&command) else {
                     err!(format!("sendmail command {command} not found in $PATH"))
                 };
+                path = which_path;
+            }
 
             match path.metadata() {
                 Err(err) if err.kind() == std::io::ErrorKind::NotFound => {
@@ -1142,12 +1156,17 @@ impl Config {
         })
     }
 
-    pub fn update_config(&self, other: ConfigBuilder) -> Result<(), Error> {
+    pub fn update_config(&self, other: ConfigBuilder, ignore_non_editable: bool) -> Result<(), Error> {
         // Remove default values
         //let builder = other.remove(&self.inner.read().unwrap()._env);
 
         // TODO: Remove values that are defaults, above only checks those set by env and not the defaults
-        let builder = other;
+        let mut builder = other;
+
+        // Remove values that are not editable
+        if ignore_non_editable {
+            builder.clear_non_editable();
+        }
 
         // Serialize now before we consume the builder
         let config_str = serde_json::to_string_pretty(&builder)?;
@@ -1182,7 +1201,7 @@ impl Config {
             let mut _overrides = Vec::new();
             usr.merge(&other, false, &mut _overrides)
         };
-        self.update_config(builder)
+        self.update_config(builder, false)
     }
 
     /// Tests whether an email's domain is allowed. A domain is allowed if it

src/mail.rs

@@ -22,7 +22,11 @@ use crate::{
 };
 
 fn sendmail_transport() -> AsyncSendmailTransport<Tokio1Executor> {
+    if let Some(command) = CONFIG.sendmail_command() {
+        AsyncSendmailTransport::new_with_command(command)
+    } else {
         AsyncSendmailTransport::new_with_command(format!("sendmail{EXE_SUFFIX}"))
+    }
 }
 
 fn smtp_transport() -> AsyncSmtpTransport<Tokio1Executor> {