console: check parameter mutual exclusivity

- Introduce `InvalidCmdlineOption` error type to handle conflicting parameters
- Implement backend-specific parameter checks:
  * Nested backend:
    - Require single socket (socket_count=1)
    - Disallow TCP port/UDS path
  * Network backend: Disallow UDS path
  * UDS backend: Disallow TCP port
- Remove default TCP port value to enforce explicit configuration

Signed-off-by: Hang SU <[email protected]>

Author: Hang SU

vhost-device-console/src/backend.rs

@@ -42,6 +42,8 @@ pub enum Error {
     ThreadPanic(String, Box<dyn Any + Send>),
     #[error("Error using multiple sockets with Nested backend")]
     WrongBackendSocket,
+    #[error("Invalid cmdline option")]
+    InvalidCmdlineOption,
     #[error("Invalid uds file")]
     InvalidUdsFile,
 }
@@ -217,7 +219,7 @@ mod tests {
             socket_path: String::from("/tmp/vhost.sock").into(),
             uds_path: None,
             backend: BackendType::Nested,
-            tcp_port: String::from("12345"),
+            tcp_port: None,
             socket_count: 1,
             max_queue_size: DEFAULT_QUEUE_SIZE,
         };
@@ -231,7 +233,7 @@ mod tests {
             socket_path: String::from("/tmp/vhost.sock").into(),
             uds_path: None,
             backend: BackendType::Nested,
-            tcp_port: String::from("12345"),
+            tcp_port: None,
             socket_count: 0,
             max_queue_size: DEFAULT_QUEUE_SIZE,
         };
@@ -248,7 +250,7 @@ mod tests {
             socket_path: String::from("/tmp/vhost.sock").into(),
             uds_path: None,
             backend: BackendType::Nested,
-            tcp_port: String::from("12345"),
+            tcp_port: None,
             socket_count: 2,
             max_queue_size: DEFAULT_QUEUE_SIZE,
         };
@@ -265,7 +267,7 @@ mod tests {
             socket_path: String::from("/tmp/vhost.sock").into(),
             uds_path: None,
             backend: BackendType::Network,
-            tcp_port: String::from("12345"),
+            tcp_port: Some(String::from("12345")),
             socket_count: 1,
             max_queue_size: DEFAULT_QUEUE_SIZE,
         };
@@ -279,7 +281,7 @@ mod tests {
             socket_path: String::from("/tmp/vhost.sock").into(),
             uds_path: None,
             backend: BackendType::Network,
-            tcp_port: String::from("12345"),
+            tcp_port: Some(String::from("12345")),
             socket_count: 2,
             max_queue_size: DEFAULT_QUEUE_SIZE,
         };
@@ -310,7 +312,7 @@ mod tests {
             socket_path: String::from("/not_a_dir/vhost.sock").into(),
             uds_path: None,
             backend: BackendType::Network,
-            tcp_port: String::from("12345"),
+            tcp_port: Some(String::from("12345")),
             socket_count: 1,
             max_queue_size: DEFAULT_QUEUE_SIZE,
         };
@@ -338,7 +340,7 @@ mod tests {
             socket_path: PathBuf::from("/tmp/vhost.sock"),
             uds_path: Some("/non_existing_dir/test.sock".to_string().into()),
             backend: BackendType::Uds,
-            tcp_port: String::new(),
+            tcp_port: Some(String::new()),
             socket_count: 1,
             max_queue_size: 128,
         };

vhost-device-console/src/main.rs

@@ -70,8 +70,8 @@ struct ConsoleArgs {
     /// Initial tcp port to be used with `network` backend. If socket_count is
     /// `N` then the following tcp ports will be created: `tcp_port`,
     /// `tcp_port + 1`, ... , `tcp_port + (N - 1)`.
-    #[clap(short = 'p', long, value_name = "PORT", default_value = "12345")]
-    tcp_port: String,
+    #[clap(short = 'p', long, value_name = "PORT")]
+    tcp_port: Option<String>,
 
     /// Specify the maximum size of virtqueue, the default is 128.
     #[clap(short = 'q', long, default_value_t = DEFAULT_QUEUE_SIZE)]
@@ -86,8 +86,34 @@ impl TryFrom<ConsoleArgs> for VuConsoleConfig {
             return Err(Error::SocketCountInvalid(0));
         }
 
-        if (args.backend == BackendType::Nested) && (args.socket_count != 1) {
-            return Err(Error::WrongBackendSocket);
+        if args.backend == BackendType::Nested {
+            if args.socket_count != 1 {
+                return Err(Error::WrongBackendSocket);
+            }
+
+            if (args.tcp_port.as_ref().map_or(false, |s| !s.is_empty()))
+                || (args
+                    .uds_path
+                    .as_ref()
+                    .map_or(false, |path| !path.as_os_str().is_empty()))
+            {
+                return Err(Error::InvalidCmdlineOption);
+            }
+        }
+
+        if args.backend == BackendType::Network
+            && args
+                .uds_path
+                .as_ref()
+                .map_or(false, |path| !path.as_os_str().is_empty())
+        {
+            return Err(Error::InvalidCmdlineOption);
+        }
+
+        if args.backend == BackendType::Uds
+            && args.tcp_port.as_ref().map_or(false, |s| !s.is_empty())
+        {
+            return Err(Error::InvalidCmdlineOption);
         }
 
         let ConsoleArgs {
@@ -117,7 +143,7 @@ impl TryFrom<ConsoleArgs> for VuConsoleConfig {
             socket_path,
             uds_path: uds_path.unwrap_or_default(),
             backend,
-            tcp_port,
+            tcp_port: tcp_port.unwrap_or_default(),
             socket_count,
             max_queue_size,
         })