Add support for tcp_user_timeout (#503)

* Add support for tcp_user_timeout

* option

* duration

* Some()

* docs

* fmt, compile

CONFIG.md

@@ -151,7 +151,13 @@ path: general.tcp_keepalives_interval
 default: 5
 ```
 
-Number of seconds between keepalive packets.
+### tcp_user_timeout
+```
+path: general.tcp_user_timeout
+default: 10000
+```
+A linux-only parameters that defines the amount of time in milliseconds that transmitted data may remain unacknowledged or buffered data may remain untransmitted (due to zero window size) before TCP will forcibly disconnect
+
 
 ### tls_certificate
 ```

src/config.rs

@@ -261,6 +261,8 @@ pub struct General {
     pub tcp_keepalives_count: u32,
     #[serde(default = "General::default_tcp_keepalives_interval")]
     pub tcp_keepalives_interval: u64,
+    #[serde(default = "General::default_tcp_user_timeout")]
+    pub tcp_user_timeout: u64,
 
     #[serde(default)] // False
     pub log_client_connections: bool,
@@ -360,6 +362,10 @@ impl General {
         5 // 5 seconds
     }
 
+    pub fn default_tcp_user_timeout() -> u64 {
+        10000 // 10000 milliseconds
+    }
+
     pub fn default_idle_timeout() -> u64 {
         600000 // 10 minutes
     }
@@ -427,6 +433,7 @@ impl Default for General {
             tcp_keepalives_idle: Self::default_tcp_keepalives_idle(),
             tcp_keepalives_count: Self::default_tcp_keepalives_count(),
             tcp_keepalives_interval: Self::default_tcp_keepalives_interval(),
+            tcp_user_timeout: Self::default_tcp_user_timeout(),
             log_client_connections: false,
             log_client_disconnections: false,
             autoreload: None,

src/messages.rs

@@ -669,6 +669,13 @@ pub fn configure_socket(stream: &TcpStream) {
     let sock_ref = SockRef::from(stream);
     let conf = get_config();
 
+    #[cfg(target_os = "linux")]
+    match sock_ref.set_tcp_user_timeout(Some(Duration::from_millis(conf.general.tcp_user_timeout)))
+    {
+        Ok(_) => (),
+        Err(err) => error!("Could not configure tcp_user_timeout for socket: {}", err),
+    }
+
     match sock_ref.set_keepalive(true) {
         Ok(_) => {
             match sock_ref.set_tcp_keepalive(
@@ -678,7 +685,7 @@ pub fn configure_socket(stream: &TcpStream) {
                     .with_time(Duration::from_secs(conf.general.tcp_keepalives_idle)),
             ) {
                 Ok(_) => (),
-                Err(err) => error!("Could not configure socket: {}", err),
+                Err(err) => error!("Could not configure tcp_keepalive for socket: {}", err),
             }
         }
         Err(err) => error!("Could not configure socket: {}", err),