improve ssh domain support for ssh_config

This tidies up how we pass the ssh config to the connection ui
logic, by moving the ssh_config setup to the two callers.

A couple of notable adjustments:

* SshDomain::username is now optional; it will default to the
  values computed by the ssh config file loader
* no_agent_auth value wasn't hooked up to anything, but now it is

refs: https://github.com/wez/wezterm/issues/730

config/src/ssh.rs

@@ -16,7 +16,7 @@ pub struct SshDomain {
     pub no_agent_auth: bool,
 
     /// The username to use for authenticating with the remote host
-    pub username: String,
+    pub username: Option<String>,
 
     /// If true, connect to this domain automatically at startup
     #[serde(default)]

mux/src/ssh.rs

@@ -52,33 +52,14 @@ impl LineEditorHost for PasswordPromptHost {
 }
 
 pub fn ssh_connect_with_ui(
-    remote_address: &str,
-    username: Option<&str>,
+    ssh_config: wezterm_ssh::ConfigMap,
     ui: &mut ConnectionUI,
 ) -> anyhow::Result<Session> {
     let cloned_ui = ui.clone();
     cloned_ui.run_and_log_error(move || {
-        let mut ssh_config = wezterm_ssh::Config::new();
-        ssh_config.add_default_config_files();
-
-        let (remote_host_name, port) = {
-            let parts: Vec<&str> = remote_address.split(':').collect();
-
-            if parts.len() == 2 {
-                (parts[0], Some(parts[1].parse::<u16>()?))
-            } else {
-                (remote_address, None)
-            }
-        };
-
-        let mut ssh_config = ssh_config.for_host(&remote_host_name);
-        if let Some(username) = username {
-            ssh_config.insert("user".to_string(), username.to_string());
-        }
-        if let Some(port) = port {
-            ssh_config.insert("port".to_string(), port.to_string());
-        }
-
+        let remote_address = ssh_config
+            .get("hostname")
+            .expect("ssh config to always set hostname");
         ui.output_str(&format!("Connecting to {} using SSH\n", remote_address));
         let (session, events) = Session::connect(ssh_config.clone())?;
 

wezterm-client/src/client.rs

@@ -427,7 +427,31 @@ impl Reconnectable {
         initial: bool,
         ui: &mut ConnectionUI,
     ) -> anyhow::Result<()> {
-        let sess = ssh_connect_with_ui(&ssh_dom.remote_address, Some(&ssh_dom.username), ui)?;
+        let mut ssh_config = wezterm_ssh::Config::new();
+        ssh_config.add_default_config_files();
+
+        let (remote_host_name, port) = {
+            let parts: Vec<&str> = ssh_dom.remote_address.split(':').collect();
+
+            if parts.len() == 2 {
+                (parts[0], Some(parts[1].parse::<u16>()?))
+            } else {
+                (ssh_dom.remote_address.as_str(), None)
+            }
+        };
+
+        let mut ssh_config = ssh_config.for_host(&remote_host_name);
+        if let Some(username) = &ssh_dom.username {
+            ssh_config.insert("user".to_string(), username.to_string());
+        }
+        if let Some(port) = port {
+            ssh_config.insert("port".to_string(), port.to_string());
+        }
+        if ssh_dom.no_agent_auth {
+            ssh_config.insert("identitiesonly".to_string(), "yes".to_string());
+        }
+
+        let sess = ssh_connect_with_ui(ssh_config, ui)?;
         let proxy_bin = Self::wezterm_bin_path(&ssh_dom.remote_wezterm_path);
 
         let cmd = if initial {
@@ -579,11 +603,25 @@ impl Reconnectable {
         if let Some(Ok(ssh_params)) = tls_client.ssh_parameters() {
             if self.tls_creds.is_none() {
                 // We need to bootstrap via an ssh session
-                let sess = ssh_connect_with_ui(
-                    &ssh_params.host_and_port,
-                    ssh_params.username.as_ref().map(|s| s.as_str()),
-                    ui,
-                )?;
+
+                let mut ssh_config = wezterm_ssh::Config::new();
+                ssh_config.add_default_config_files();
+
+                let mut fields = ssh_params.host_and_port.split(':');
+                let host = fields
+                    .next()
+                    .ok_or_else(|| anyhow::anyhow!("no host component somehow"))?;
+                let port = fields.next();
+
+                let mut ssh_config = ssh_config.for_host(host);
+                if let Some(username) = &ssh_params.username {
+                    ssh_config.insert("user".to_string(), username.to_string());
+                }
+                if let Some(port) = port {
+                    ssh_config.insert("port".to_string(), port.to_string());
+                }
+
+                let sess = ssh_connect_with_ui(ssh_config, ui)?;
 
                 let creds = ui.run_and_log_error(|| {
                     // The `tlscreds` command will start the server if needed and then

wezterm-client/src/domain.rs

@@ -129,7 +129,11 @@ impl ClientDomainConfig {
             ClientDomainConfig::Unix(unix) => format!("unix mux {}", unix.socket_path().display()),
             ClientDomainConfig::Tls(tls) => format!("TLS mux {}", tls.remote_address),
             ClientDomainConfig::Ssh(ssh) => {
-                format!("SSH mux {}@{}", ssh.username, ssh.remote_address)
+                if let Some(user) = &ssh.username {
+                    format!("SSH mux {}@{}", user, ssh.remote_address)
+                } else {
+                    format!("SSH mux {}", ssh.remote_address)
+                }
             }
         }
     }