Expand SSH identity path tokens

Cargo.lock

@@ -436,7 +436,7 @@ dependencies = [
 
 [[package]]
 name = "dosh"
-version = "1.0.0-rc27"
+version = "1.0.0-rc28"
 dependencies = [
  "anyhow",
  "base64",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dosh"
-version = "1.0.0-rc27"
+version = "1.0.0-rc28"
 edition = "2024"
 license = "MIT"
 

src/bin/dosh-client.rs

@@ -4032,7 +4032,7 @@ async fn try_native_auth(
     let auth = sign_native_user_auth(
         config,
         cli_identity,
-        ssh_config,
+        &NativeIdentityContext::new(server, ssh_port, ssh_config),
         &hello,
         &server_hello.hello,
         requested_forwardings,
@@ -4183,7 +4183,7 @@ async fn try_native_auth_check(
     let auth = sign_native_user_auth(
         config,
         cli_identity,
-        ssh_config,
+        &NativeIdentityContext::new(server, ssh_port, ssh_config),
         &hello,
         &server_hello.hello,
         Vec::new(),
@@ -4218,13 +4218,14 @@ async fn try_native_auth_check(
 fn sign_native_user_auth(
     config: &dosh::config::ClientConfig,
     cli_identity: Option<&Path>,
-    ssh_config: &SshConfig,
+    identity_context: &NativeIdentityContext<'_>,
     hello: &dosh::native::NativeClientHello,
     server_hello: &dosh::native::NativeServerHello,
     requested_forwardings: Vec<ForwardingRequest>,
     allow_passphrase_prompt: bool,
 ) -> Result<dosh::native::NativeUserAuth> {
     let mut errors = Vec::new();
+    let ssh_config = identity_context.ssh_config;
     if config.use_ssh_agent && !ssh_config.identities_only {
         match ssh_agent::sign_user_auth_with_agent(
             hello,
@@ -4239,9 +4240,9 @@ fn sign_native_user_auth(
     }
 
     let identity = if allow_passphrase_prompt {
-        load_first_native_identity(config, cli_identity, ssh_config)
+        load_first_native_identity(config, cli_identity, identity_context)
     } else {
-        load_first_native_identity_noninteractive(config, cli_identity, ssh_config)
+        load_first_native_identity_noninteractive(config, cli_identity, identity_context)
     };
     match identity {
         Ok(identity) => {
@@ -4260,12 +4261,12 @@ fn sign_native_user_auth(
 fn load_first_native_identity(
     config: &dosh::config::ClientConfig,
     cli_identity: Option<&Path>,
-    ssh_config: &SshConfig,
+    identity_context: &NativeIdentityContext<'_>,
 ) -> Result<ssh_key::PrivateKey> {
     load_first_native_identity_with_prompt(
         config,
         cli_identity,
-        ssh_config,
+        identity_context,
         prompt_identity_passphrase,
     )
 }
@@ -4273,9 +4274,9 @@ fn load_first_native_identity(
 fn load_first_native_identity_noninteractive(
     config: &dosh::config::ClientConfig,
     cli_identity: Option<&Path>,
-    ssh_config: &SshConfig,
+    identity_context: &NativeIdentityContext<'_>,
 ) -> Result<ssh_key::PrivateKey> {
-    load_first_native_identity_with_prompt(config, cli_identity, ssh_config, |path| {
+    load_first_native_identity_with_prompt(config, cli_identity, identity_context, |path| {
         Err(anyhow!(
             "{} is encrypted; unlock it in ssh-agent or use an unencrypted key for proxy-stdio",
             path.display()
@@ -4286,22 +4287,30 @@ fn load_first_native_identity_noninteractive(
 fn load_first_native_identity_with_prompt<F>(
     config: &dosh::config::ClientConfig,
     cli_identity: Option<&Path>,
-    ssh_config: &SshConfig,
+    identity_context: &NativeIdentityContext<'_>,
     mut prompt: F,
 ) -> Result<ssh_key::PrivateKey>
 where
     F: FnMut(&Path) -> Result<String>,
 {
+    let ssh_config = identity_context.ssh_config;
+    let token_context = &identity_context.path_tokens;
     let mut paths = Vec::new();
     if let Some(path) = cli_identity {
         push_identity_path(&mut paths, path.to_path_buf());
     }
     for path in &ssh_config.identity_files {
-        push_identity_path(&mut paths, expand_tilde(path));
+        push_identity_path(
+            &mut paths,
+            expand_tilde(&expand_ssh_path_tokens(path, token_context)),
+        );
     }
     if !ssh_config.identities_only {
         for path in &config.identity_files {
-            push_identity_path(&mut paths, expand_tilde(path));
+            push_identity_path(
+                &mut paths,
+                expand_tilde(&expand_ssh_path_tokens(path, token_context)),
+            );
         }
     }
 
@@ -4339,6 +4348,98 @@ fn push_identity_path(paths: &mut Vec<PathBuf>, path: PathBuf) {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct SshPathTokenContext {
+    original_host: String,
+    hostname: String,
+    port: u16,
+    remote_user: String,
+    local_user: String,
+    home_dir: Option<String>,
+}
+
+struct NativeIdentityContext<'a> {
+    ssh_config: &'a SshConfig,
+    path_tokens: SshPathTokenContext,
+}
+
+impl<'a> NativeIdentityContext<'a> {
+    fn new(server: &str, ssh_port: Option<u16>, ssh_config: &'a SshConfig) -> Self {
+        Self {
+            ssh_config,
+            path_tokens: ssh_path_token_context(server, ssh_port, ssh_config),
+        }
+    }
+}
+
+fn ssh_path_token_context(
+    server: &str,
+    ssh_port: Option<u16>,
+    ssh_config: &SshConfig,
+) -> SshPathTokenContext {
+    let original_host = ssh_destination_host(server);
+    let hostname = ssh_config
+        .hostname
+        .clone()
+        .unwrap_or_else(|| original_host.clone());
+    let port = ssh_config.port.or(ssh_port).unwrap_or(22);
+    let remote_user = ssh_username(server)
+        .or(ssh_config.user.clone())
+        .unwrap_or_else(local_username);
+    let local_user = local_username();
+    let home_dir = dirs::home_dir().map(|path| path.to_string_lossy().to_string());
+    SshPathTokenContext {
+        original_host,
+        hostname,
+        port,
+        remote_user,
+        local_user,
+        home_dir,
+    }
+}
+
+fn local_username() -> String {
+    std::env::var("USER")
+        .or_else(|_| std::env::var("USERNAME"))
+        .unwrap_or_else(|_| "unknown".to_string())
+}
+
+fn expand_ssh_path_tokens(path: &str, context: &SshPathTokenContext) -> String {
+    let mut out = String::with_capacity(path.len());
+    let mut chars = path.chars();
+    while let Some(ch) = chars.next() {
+        if ch != '%' {
+            out.push(ch);
+            continue;
+        }
+        let Some(token) = chars.next() else {
+            out.push('%');
+            break;
+        };
+        match token {
+            '%' => out.push('%'),
+            'd' => {
+                if let Some(home_dir) = &context.home_dir {
+                    out.push_str(home_dir);
+                } else {
+                    out.push('%');
+                    out.push(token);
+                }
+            }
+            'h' => out.push_str(&context.hostname),
+            'n' => out.push_str(&context.original_host),
+            'p' => out.push_str(&context.port.to_string()),
+            'r' => out.push_str(&context.remote_user),
+            'u' => out.push_str(&context.local_user),
+            other => {
+                out.push('%');
+                out.push(other);
+            }
+        }
+    }
+    out
+}
+
 fn prompt_identity_passphrase(path: &Path) -> Result<String> {
     rpassword::prompt_password(format!("Enter passphrase for {}: ", path.display()))
         .with_context(|| format!("read passphrase for {}", path.display()))
@@ -7941,27 +8042,27 @@ mod tests {
     use super::{
         ALT_SCREEN_IDLE_REPAINT_AFTER, CachedCredential, DisconnectStatus, DynamicForward,
         FRAME_GAP_RESYNC_AFTER_MS, FrameBuffer, LocalForward, MAX_PENDING_USER_INPUT_BYTES,
-        POST_SUBMIT_ALL_INPUT_HOLD, PendingStreamOpen, PredictMode, Predictor,
-        RESTART_STATUS_SCRIPT, RemoteForward, STARTUP_INPUT_HOLD, SshConfig, StartupGateMode,
-        StatusAction, UpdateOptions, UpdateRole, auth_allows, cache_key, cache_server_prefix,
-        cleanup_stream_state, clear_cached_credentials, ensure_tui_safe_status_overlay,
-        input_contains_focus_in, input_matches_escape, is_local_status_target,
-        is_resume_response_for_client, latest_release_download_url,
-        load_first_native_identity_with_prompt, native_proxy_udp_warning, parse_dynamic_forward,
-        parse_escape_key, parse_local_forward, parse_remote_forward, parse_ssh_config,
-        parse_update_options, post_submit_hold_duration, queue_pending_user_input,
-        raw_contains_host_table, recv_response_until, refresh_live_addr, release_tag_download_url,
-        release_tag_from_effective_url, release_version_from_tag, render_status_clear,
-        render_status_overlay, requested_env, resolved_startup_command, retire_stream_state,
-        retransmit_stream_opens, rewrite_forward_command, selected_predict_mode, selected_udp_host,
-        server_version_mismatch, should_flush_terminal_input_after_contact,
-        should_hold_during_startup_gate, should_hold_post_submit_input,
-        should_repaint_idle_alternate_screen, split_after_command_submit, ssh_command_target,
-        ssh_config_uses_proxy, ssh_destination_host, ssh_username, ssh_with_user, startup_command,
-        status_ssh_target, strip_stale_mouse_reports, strip_terminal_focus_reports,
-        terminal_private_mode_transition, toml_bare_key_or_quoted, unix_update_script,
-        update_installer_url, update_version_status, upsert_managed_block, valid_forward_host,
-        vscode_safe_alias, windows_update_script,
+        NativeIdentityContext, POST_SUBMIT_ALL_INPUT_HOLD, PendingStreamOpen, PredictMode,
+        Predictor, RESTART_STATUS_SCRIPT, RemoteForward, STARTUP_INPUT_HOLD, SshConfig,
+        SshPathTokenContext, StartupGateMode, StatusAction, UpdateOptions, UpdateRole, auth_allows,
+        cache_key, cache_server_prefix, cleanup_stream_state, clear_cached_credentials,
+        ensure_tui_safe_status_overlay, expand_ssh_path_tokens, input_contains_focus_in,
+        input_matches_escape, is_local_status_target, is_resume_response_for_client,
+        latest_release_download_url, load_first_native_identity_with_prompt,
+        native_proxy_udp_warning, parse_dynamic_forward, parse_escape_key, parse_local_forward,
+        parse_remote_forward, parse_ssh_config, parse_update_options, post_submit_hold_duration,
+        queue_pending_user_input, raw_contains_host_table, recv_response_until, refresh_live_addr,
+        release_tag_download_url, release_tag_from_effective_url, release_version_from_tag,
+        render_status_clear, render_status_overlay, requested_env, resolved_startup_command,
+        retire_stream_state, retransmit_stream_opens, rewrite_forward_command,
+        selected_predict_mode, selected_udp_host, server_version_mismatch,
+        should_flush_terminal_input_after_contact, should_hold_during_startup_gate,
+        should_hold_post_submit_input, should_repaint_idle_alternate_screen,
+        split_after_command_submit, ssh_command_target, ssh_config_uses_proxy,
+        ssh_destination_host, ssh_username, ssh_with_user, startup_command, status_ssh_target,
+        strip_stale_mouse_reports, strip_terminal_focus_reports, terminal_private_mode_transition,
+        toml_bare_key_or_quoted, unix_update_script, update_installer_url, update_version_status,
+        upsert_managed_block, valid_forward_host, vscode_safe_alias, windows_update_script,
     };
     use dosh::config::{ClientConfig, CommandExtension, HostConfig};
     use dosh::native::EnvVar;
@@ -8346,6 +8447,26 @@ mod tests {
         }));
     }
 
+    #[test]
+    fn ssh_identity_paths_expand_common_openssh_tokens() {
+        let context = SshPathTokenContext {
+            original_host: "prod".to_string(),
+            hostname: "10.0.0.5".to_string(),
+            port: 2222,
+            remote_user: "deploy".to_string(),
+            local_user: "palav".to_string(),
+            home_dir: Some("/home/palav".to_string()),
+        };
+        assert_eq!(
+            expand_ssh_path_tokens("~/.ssh/%r@%h:%p-%n-%u-%%-%x", &context),
+            "~/.ssh/deploy@10.0.0.5:2222-prod-palav-%-%x"
+        );
+        assert_eq!(
+            expand_ssh_path_tokens("%d/.ssh/%r_%h", &context),
+            "/home/palav/.ssh/deploy_10.0.0.5"
+        );
+    }
+
     #[test]
     fn native_proxy_udp_warning_requires_missing_explicit_dosh_host() {
         let proxied = SshConfig {
@@ -8403,13 +8524,14 @@ mod tests {
         write_encrypted_identity(&path, &signing, "let-me-in");
         let mut config = ClientConfig::default();
         config.identity_files.clear();
-        let loaded = load_first_native_identity_with_prompt(
-            &config,
-            Some(&path),
-            &SshConfig::default(),
-            |_| Ok("let-me-in".to_string()),
-        )
-        .unwrap();
+        let ssh_config = SshConfig::default();
+        let identity_context =
+            NativeIdentityContext::new("alice@example.com", Some(2222), &ssh_config);
+        let loaded =
+            load_first_native_identity_with_prompt(&config, Some(&path), &identity_context, |_| {
+                Ok("let-me-in".to_string())
+            })
+            .unwrap();
 
         assert_eq!(
             loaded.public_key().key_data().ed25519().unwrap().as_ref(),
@@ -8425,13 +8547,14 @@ mod tests {
         write_encrypted_identity(&path, &signing, "correct");
         let mut config = ClientConfig::default();
         config.identity_files.clear();
-        let err = load_first_native_identity_with_prompt(
-            &config,
-            Some(&path),
-            &SshConfig::default(),
-            |_| Ok("wrong".to_string()),
-        )
-        .unwrap_err();
+        let ssh_config = SshConfig::default();
+        let identity_context =
+            NativeIdentityContext::new("alice@example.com", Some(2222), &ssh_config);
+        let err =
+            load_first_native_identity_with_prompt(&config, Some(&path), &identity_context, |_| {
+                Ok("wrong".to_string())
+            })
+            .unwrap_err();
 
         assert!(err.to_string().contains("no usable native identity"));
     }
@@ -8450,7 +8573,9 @@ mod tests {
             identities_only: true,
             ..SshConfig::default()
         };
-        let err = load_first_native_identity_with_prompt(&config, None, &ssh_config, |_| {
+        let identity_context =
+            NativeIdentityContext::new("alice@example.com", Some(2222), &ssh_config);
+        let err = load_first_native_identity_with_prompt(&config, None, &identity_context, |_| {
             unreachable!("unencrypted key should not prompt")
         })
         .unwrap_err();
@@ -8471,10 +8596,41 @@ mod tests {
             identities_only: true,
             ..SshConfig::default()
         };
-        let loaded = load_first_native_identity_with_prompt(&config, None, &ssh_config, |_| {
-            unreachable!("unencrypted key should not prompt")
-        })
-        .unwrap();
+        let identity_context =
+            NativeIdentityContext::new("alice@example.com", Some(2222), &ssh_config);
+        let loaded =
+            load_first_native_identity_with_prompt(&config, None, &identity_context, |_| {
+                unreachable!("unencrypted key should not prompt")
+            })
+            .unwrap();
+
+        assert_eq!(
+            loaded.public_key().key_data().ed25519().unwrap().as_ref(),
+            VerifyingKey::from(&signing).as_bytes()
+        );
+    }
+
+    #[test]
+    fn ssh_config_identity_file_tokens_are_expanded_for_native_auth() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("deploy_10.0.0.5_2222");
+        let signing = SigningKey::from_bytes(&[65u8; 32]);
+        write_identity(&path, &signing);
+        let mut config = ClientConfig::default();
+        config.identity_files.clear();
+        let ssh_config = SshConfig {
+            hostname: Some("10.0.0.5".to_string()),
+            identity_files: vec![format!("{}/%r_%h_%p", dir.path().display())],
+            identities_only: true,
+            port: Some(2222),
+            ..SshConfig::default()
+        };
+        let identity_context = NativeIdentityContext::new("deploy@prod", None, &ssh_config);
+        let loaded =
+            load_first_native_identity_with_prompt(&config, None, &identity_context, |_| {
+                unreachable!("unencrypted key should not prompt")
+            })
+            .unwrap();
 
         assert_eq!(
             loaded.public_key().key_data().ed25519().unwrap().as_ref(),