Harden Windows SSH config quoting

src/bin/dosh-client.rs

@@ -4711,13 +4711,46 @@ fn shell_word(value: &str) -> String {
 }
 
 fn ssh_config_word(value: &str) -> String {
-    if cfg!(windows) {
-        format!("\"{}\"", value.replace('"', "\\\""))
+    ssh_config_word_for_os(std::env::consts::OS, value)
+}
+
+fn ssh_config_word_for_os(os: &str, value: &str) -> String {
+    if os == "windows" {
+        windows_command_word(value)
     } else {
         shell_word(value)
     }
 }
 
+fn windows_command_word(value: &str) -> String {
+    let mut out = String::from("\"");
+    let mut backslashes = 0usize;
+    for ch in value.chars() {
+        if ch == '\\' {
+            backslashes += 1;
+            continue;
+        }
+        if ch == '"' {
+            for _ in 0..(backslashes * 2 + 1) {
+                out.push('\\');
+            }
+            out.push('"');
+            backslashes = 0;
+            continue;
+        }
+        for _ in 0..backslashes {
+            out.push('\\');
+        }
+        backslashes = 0;
+        out.push(ch);
+    }
+    for _ in 0..(backslashes * 2) {
+        out.push('\\');
+    }
+    out.push('"');
+    out
+}
+
 fn local_bootstrap(
     session: &str,
     mode: &str,
@@ -10135,12 +10168,13 @@ mod tests {
         should_hold_post_submit_input, should_reconnect_before_input_for_local_sleep,
         should_repaint_idle_terminal, should_strip_unowned_terminal_reports,
         split_after_command_submit, split_trace_tokens, 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, strip_unowned_terminal_reports,
-        summarize_trace_file, summarize_trace_file_with_mode, terminal_private_mode_transition,
-        toml_bare_key_or_quoted, top_trace_events, trace_report_warnings, unix_update_script,
-        update_binary_version_for_installer, update_installer_url, update_version_status,
-        upsert_managed_block, valid_forward_host, vscode_safe_alias, wake_repaint_retry_deadline,
+        ssh_config_word_for_os, ssh_destination_host, ssh_username, ssh_with_user, startup_command,
+        status_ssh_target, strip_stale_mouse_reports, strip_terminal_focus_reports,
+        strip_unowned_terminal_reports, summarize_trace_file, summarize_trace_file_with_mode,
+        terminal_private_mode_transition, toml_bare_key_or_quoted, top_trace_events,
+        trace_report_warnings, unix_update_script, update_binary_version_for_installer,
+        update_installer_url, update_version_status, upsert_managed_block, valid_forward_host,
+        vscode_safe_alias, wake_repaint_retry_deadline, windows_command_word,
         windows_mode_from_readonly, windows_readonly_from_mode, windows_update_script,
     };
     use dosh::config::{ClientConfig, CommandExtension, HostConfig};
@@ -10503,6 +10537,31 @@ mod tests {
         );
     }
 
+    #[test]
+    fn ssh_config_word_quotes_for_unix_and_windows() {
+        assert_eq!(
+            ssh_config_word_for_os("linux", "/Users/palav/My App/dosh"),
+            "'/Users/palav/My App/dosh'"
+        );
+        assert_eq!(
+            ssh_config_word_for_os("windows", r#"C:\Users\palav\My App\dosh.exe"#),
+            r#""C:\Users\palav\My App\dosh.exe""#
+        );
+    }
+
+    #[test]
+    fn windows_command_word_escapes_quotes_and_trailing_backslashes() {
+        assert_eq!(
+            windows_command_word(r#"C:\Program Files\dosh\"#),
+            r#""C:\Program Files\dosh\\""#
+        );
+        assert_eq!(windows_command_word(r#"say "hi""#), r#""say \"hi\"""#);
+        assert_eq!(
+            windows_command_word(r#"C:\path\before"quote"#),
+            r#""C:\path\before\"quote""#
+        );
+    }
+
     #[test]
     fn parses_ssh_config_native_parity_options() {
         let parsed = parse_ssh_config(