Add hasInternetCredentials (#150)

This checks if the username/password combination for server is available in the secure storage.
Resolves to `true` if an entry exists or `false` if it doesn't.

README.md

@@ -61,6 +61,10 @@ Will remove the username/password combination from the secure storage.
 
 Will store the server/username/password combination in the secure storage.
 
+### `hasInternetCredentials(server, [{ authenticationPrompt }])`
+
+Will check if the username/password combination for server is available in the secure storage. Resolves to `true` if an entry exists or `false` if it doesn't.
+
 ### `getInternetCredentials(server, [{ authenticationPrompt }])`
 
 Will retreive the server/username/password combination from the secure storage. Resolves to `{ username, password }` if an entry exists or `false` if it doesn't. It will reject only if an unexpected error is encountered like lacking entitlements or permission.

RNKeychainManager/RNKeychainManager.m

@@ -372,6 +372,35 @@ RCT_EXPORT_METHOD(setInternetCredentialsForServer:(NSString *)server withUsernam
   [self insertKeychainEntry:attributes withOptions:options resolver:resolve rejecter:reject];
 }
 
+RCT_EXPORT_METHOD(hasInternetCredentialsForServer:(NSString *)server resolver:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject)
+{
+  NSMutableDictionary *queryParts = [[NSMutableDictionary alloc] init];
+  queryParts[(__bridge NSString *)kSecClass] = (__bridge id)(kSecClassInternetPassword);
+  queryParts[(__bridge NSString *)kSecAttrServer] = server;
+  queryParts[(__bridge NSString *)kSecMatchLimit] = (__bridge NSString *)kSecMatchLimitOne;
+
+  if (@available(iOS 9, *)) {
+    queryParts[(__bridge NSString *)kSecUseAuthenticationUI] = (__bridge NSString *)kSecUseAuthenticationUIFail;
+  }
+
+  NSDictionary *query = [queryParts copy];
+
+  // Look up server in the keychain
+  OSStatus osStatus = SecItemCopyMatching((__bridge CFDictionaryRef) query, nil);
+
+  switch (osStatus) {
+    case noErr:
+    case errSecInteractionNotAllowed:
+      return resolve(@(YES));
+
+    case errSecItemNotFound:
+      return resolve(@(NO));
+  }
+
+  NSError *error = [NSError errorWithDomain:NSOSStatusErrorDomain code:osStatus userInfo:nil];
+  return rejectWithError(reject, error);
+}
+
 RCT_EXPORT_METHOD(getInternetCredentialsForServer:(NSString *)server withOptions:(NSDictionary *)options resolver:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject)
 {
   NSDictionary *query = @{

android/src/main/java/com/oblador/keychain/KeychainModule.java

@@ -149,6 +149,19 @@ public class KeychainModule extends ReactContextBaseJavaModule {
         }
     }
 
+    public void hasInternetCredentialsForServer(@NonNull String server, Promise promise) {
+        final String defaultService = getDefaultServiceIfNull(server);
+
+        ResultSet resultSet = prefsStorage.getEncryptedEntry(defaultService);
+        if (resultSet == null) {
+            Log.e(KEYCHAIN_MODULE, "No entry found for service: " + defaultService);
+            promise.resolve(false);
+            return;
+        }
+
+        promise.resolve(true);
+    }
+
     @ReactMethod
     public void setInternetCredentialsForServer(@NonNull String server, String username, String password, ReadableMap unusedOptions, Promise promise) {
         setGenericPasswordForOptions(server, username, password, promise);

index.js

@@ -108,6 +108,17 @@ export function setInternetCredentials(
   );
 }
 
+/**
+ * Checks if we have a login combination for `server`.
+ * @param {string} server URL to server.
+ * @return {Promise} Resolves to `true` when successful
+ */
+export function hasInternetCredentials(
+  server: string,
+): Promise {
+  return RNKeychainManager.hasInternetCredentialsForServer(server);
+}
+
 /**
  * Fetches login combination for `server`.
  * @param {string} server URL to server.

typings/react-native-keychain.d.ts

@@ -63,6 +63,10 @@ declare module 'react-native-keychain' {
         server: string
     ): Promise<UserCredentials>;
 
+    function hasInternetCredentials(
+        server: string
+    ): Promise<boolean>;
+
     function resetInternetCredentials(
         server: string
     ): Promise<void>;