Support host-config login users

docs/NATIVE_V1_SPEC.md

@@ -69,7 +69,7 @@ Must work in v1:
 - Encrypted OpenSSH private-key authentication with prompt.
 - `~/.ssh/config` host aliases for `Host`, `HostName`, `User`, `Port`,
   `IdentityFile`, `ProxyJump`, `UserKnownHostsFile`, and `IdentitiesOnly`.
-- Dosh host config overrides for Dosh-specific UDP host/port/auth policy.
+- Dosh host config overrides for user, Dosh-specific UDP host/port/auth policy.
 - Clear host-key trust and mismatch errors.
 - Clear auth failure errors that name the attempted key source.
 - Stable reconnect after sleep, network switch, NAT rebinding, and server packet loss.

src/bin/dosh-client.rs

@@ -173,7 +173,8 @@ async fn main() -> Result<()> {
         .get(&requested_server)
         .cloned()
         .unwrap_or_default();
-    let server = host.ssh.clone().unwrap_or_else(|| requested_server.clone());
+    let raw_server = host.ssh.clone().unwrap_or_else(|| requested_server.clone());
+    let server = ssh_with_user(&raw_server, host.user.as_deref());
     let startup_command = startup_command(&args.command).or_else(|| {
         host.default_command
             .as_deref()
@@ -490,7 +491,8 @@ fn run_trust_command(config: &dosh::config::ClientConfig, args: &Args) -> Result
 
     let hosts = load_hosts_config(None).unwrap_or_default();
     let host_config = hosts.hosts.get(host).cloned().unwrap_or_default();
-    let server = host_config.ssh.clone().unwrap_or_else(|| host.to_string());
+    let raw_server = host_config.ssh.clone().unwrap_or_else(|| host.to_string());
+    let server = ssh_with_user(&raw_server, host_config.user.as_deref());
     let ssh_port = args.ssh_port.or(host_config.ssh_port).or(config.ssh_port);
     let ssh_auth_command = args
         .ssh_auth_command
@@ -531,7 +533,8 @@ async fn run_doctor_command(config: &dosh::config::ClientConfig, args: &Args) ->
         .ok_or_else(|| anyhow!("usage: dosh doctor <host>"))?;
     let hosts = load_hosts_config(None).unwrap_or_default();
     let host_config = hosts.hosts.get(&requested).cloned().unwrap_or_default();
-    let server = host_config.ssh.clone().unwrap_or_else(|| requested.clone());
+    let raw_server = host_config.ssh.clone().unwrap_or_else(|| requested.clone());
+    let server = ssh_with_user(&raw_server, host_config.user.as_deref());
     let ssh_port = args.ssh_port.or(host_config.ssh_port).or(config.ssh_port);
     let dosh_port = args
         .dosh_port
@@ -994,6 +997,9 @@ fn run_import_ssh(config: &dosh::config::ClientConfig, aliases: &[String]) -> Re
         raw.push_str(&format!("ssh = {}\n", toml_string(alias)));
         raw.push_str(&format!("dosh_host = {}\n", toml_string(&udp_host)));
         raw.push_str(&format!("port = {}\n", config.dosh_port));
+        if let Some(user) = &ssh_config.user {
+            raw.push_str(&format!("user = {}\n", toml_string(user)));
+        }
         if let Some(port) = ssh_config.port
             && port != 22
         {
@@ -1183,6 +1189,17 @@ fn ssh_username(server: &str) -> Option<String> {
     }
 }
 
+fn ssh_with_user(server: &str, user: Option<&str>) -> String {
+    let Some(user) = user else {
+        return server.to_string();
+    };
+    if user.is_empty() || ssh_username(server).is_some() || server.starts_with("ssh://") {
+        server.to_string()
+    } else {
+        format!("{user}@{server}")
+    }
+}
+
 #[derive(Debug, Clone, Default)]
 struct SshConfig {
     hostname: Option<String>,
@@ -2964,8 +2981,8 @@ mod tests {
         DynamicForward, FrameBuffer, LocalForward, Predictor, RemoteForward, SshConfig,
         auth_allows, load_first_native_identity_with_prompt, parse_dynamic_forward,
         parse_local_forward, parse_remote_forward, parse_ssh_config, raw_contains_host_table,
-        recv_response_until, requested_env, ssh_destination_host, ssh_username, startup_command,
+        recv_response_until, requested_env, ssh_destination_host, ssh_username, ssh_with_user,
-        toml_bare_key_or_quoted,
+        startup_command, toml_bare_key_or_quoted,
     };
     use dosh::config::{ClientConfig, HostConfig};
     use dosh::native::EnvVar;
@@ -3108,6 +3125,22 @@ mod tests {
         assert_eq!(ssh_username("example.com"), None);
     }
 
+    #[test]
+    fn applies_host_config_user_to_plain_ssh_destination() {
+        assert_eq!(
+            ssh_with_user("example.com", Some("palav")),
+            "palav@example.com"
+        );
+        assert_eq!(
+            ssh_with_user("root@example.com", Some("palav")),
+            "root@example.com"
+        );
+        assert_eq!(
+            ssh_with_user("ssh://example.com", Some("palav")),
+            "ssh://example.com"
+        );
+    }
+
     #[test]
     fn auth_preference_accepts_auto_or_named_method() {
         assert!(auth_allows("native,ssh", "native"));

src/config.rs

@@ -106,6 +106,7 @@ pub struct ClientConfig {
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct HostConfig {
     pub ssh: Option<String>,
+    pub user: Option<String>,
     pub dosh_host: Option<String>,
     pub port: Option<u16>,
     pub ssh_port: Option<u16>,