auto-detect enrolled key, --email only needed for enroll/remove

src/main.rs

@@ -6,9 +6,6 @@ mod ipc;
 mod log;
 mod storage;
 
-use std::fs;
-use std::path::PathBuf;
-
 use clap::Parser;
 use sha2::{Digest, Sha256};
 use zeroize::Zeroize;
@@ -42,27 +39,6 @@ struct Args {
     remove: bool,
 }
 
-fn config_dir() -> PathBuf {
-    let home = std::env::var("HOME").unwrap_or_else(|_| "/tmp".into());
-    PathBuf::from(home).join(".cache").join("com.bitwarden.desktop")
-}
-
-fn config_path() -> PathBuf {
-    config_dir().join("agent.conf")
-}
-
-fn save_email(email: &str) {
-    fs::create_dir_all(config_dir()).ok();
-    fs::write(config_path(), email).ok();
-}
-
-fn load_email() -> Option<String> {
-    fs::read_to_string(config_path())
-        .ok()
-        .map(|s| s.trim().to_string())
-        .filter(|s| !s.is_empty())
-}
-
 fn user_hash(email: &str) -> String {
     let mut hasher = Sha256::new();
     hasher.update(email.to_lowercase().trim().as_bytes());
@@ -72,29 +48,17 @@ fn user_hash(email: &str) -> String {
 
 fn main() {
     let args = Args::parse();
-
-    let email = args
-        .email
-        .clone()
-        .or_else(load_email)
-        .unwrap_or_else(|| log::fatal("no email provided (use --email on first run)"));
-
-    let uid = user_hash(&email);
     let store = get_backend(args.backend.as_deref());
     let prompt = get_prompter(args.askpass.as_deref());
     log::info(&format!("backend: {}", store.name()));
 
-    if args.remove {
-        if store.has_key(&uid) {
-            store.remove(&uid);
-            log::info(&format!("key removed for {email}"));
-        } else {
-            log::info(&format!("no key found for {email}"));
-        }
-        return;
-    }
+    if args.enroll {
+        let email = args
+            .email
+            .as_deref()
+            .unwrap_or_else(|| log::fatal("--email required for enrollment"));
+        let uid = user_hash(email);
 
-    if !store.has_key(&uid) || args.enroll {
         log::info(if !store.has_key(&uid) {
             "enrolling"
         } else {
@@ -108,7 +72,7 @@ fn main() {
             .unwrap_or_else(|| log::fatal("no password provided"));
 
         log::info(&format!("logging in as {email}"));
-        let (mut key_bytes, server_uid) = auth::login(&email, &pw, &args.server, &prompt);
+        let (mut key_bytes, server_uid) = auth::login(email, &pw, &args.server, &prompt);
         log::info(&format!("authenticated, uid={server_uid}"));
 
         let auth = prompt(&format!("choose {} password:", store.name()))
@@ -123,13 +87,34 @@ fn main() {
             .store(&uid, &key_bytes, &auth)
             .unwrap_or_else(|e| log::fatal(&format!("store failed: {e}")));
         key_bytes.zeroize();
-        save_email(&email);
         log::info(&format!("key sealed via {}", store.name()));
         log::info("wiped key from memory");
-    } else {
-        log::info(&format!("key ready for {email}"));
+        return;
     }
 
+    if args.remove {
+        let email = args
+            .email
+            .as_deref()
+            .unwrap_or_else(|| log::fatal("--email required for --remove"));
+        let uid = user_hash(email);
+        if store.has_key(&uid) {
+            store.remove(&uid);
+            log::info(&format!("key removed for {email}"));
+        } else {
+            log::info(&format!("no key found for {email}"));
+        }
+        return;
+    }
+
+    let uid = match store.find_key() {
+        Some(uid) => {
+            log::info(&format!("found key: {uid}"));
+            uid
+        }
+        None => log::fatal("no enrolled key found (run with --email <email> --enroll first)"),
+    };
+
     let mut bridge = BiometricBridge::new(store, uid, prompt);
     let sock = ipc::socket_path();
     log::info(&format!("listening on {}", sock.display()));

src/storage/mod.rs

@@ -8,6 +8,7 @@ pub trait KeyStore {
     fn store(&self, uid: &str, data: &[u8], auth: &str) -> Result<(), String>;
     fn load(&self, uid: &str, auth: &str) -> Result<Vec<u8>, String>;
     fn remove(&self, uid: &str);
+    fn find_key(&self) -> Option<String>;
 }
 
 pub fn get_backend(preferred: Option<&str>) -> Box<dyn KeyStore> {

src/storage/pin.rs

@@ -114,6 +114,17 @@ impl KeyStore for PinKeyStore {
             fs::remove_file(p).ok();
         }
     }
+
+    fn find_key(&self) -> Option<String> {
+        let entries = fs::read_dir(&self.dir).ok()?;
+        for entry in entries.flatten() {
+            let path = entry.path();
+            if path.extension().and_then(|e| e.to_str()) == Some("enc") {
+                return path.file_stem().and_then(|s| s.to_str()).map(|s| s.to_string());
+            }
+        }
+        None
+    }
 }
 
 fn derive(password: &str, salt: &[u8]) -> Result<Zeroizing<Vec<u8>>, String> {