auth: Add ssh_userauth_publickey_auto_get_current_identity()

Signed-off-by: Marius Vollmer <mvollmer@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/auth.c

@@ -975,6 +975,55 @@ struct ssh_auth_auto_state_struct {
     ssh_key pubkey;
 };
 
+/**
+ * @brief Get the identity that is currenly being processed by
+ * ssh_userauth_publickey_auto()
+ *
+ * This is meant to be used by a callback that happens as part of the
+ * execution of ssh_userauth_publickey_auto().  The auth_function
+ * callback might want to know which key a passphrase is needed for,
+ * for example.
+ *
+ * @param[in]  session     The SSH session.
+ *
+ * @param[out] value       The value to get into. As a char**, space will be
+ *                         allocated by the function for the value, it is
+ *                         your responsibility to free the memory using
+ *                         ssh_string_free_char().
+ *
+ * @return  SSH_OK on success, SSH_ERROR on error.
+ */
+int ssh_userauth_publickey_auto_get_current_identity(ssh_session session,
+                                                     char** value)
+{
+    const char *id = NULL;
+
+    if (session == NULL) {
+        return SSH_ERROR;
+    }
+
+    if (value == NULL) {
+        ssh_set_error_invalid(session);
+        return SSH_ERROR;
+    }
+
+    if (session->auth.auto_state != NULL && session->auth.auto_state->it != NULL) {
+        id = session->auth.auto_state->it->data;
+    }
+
+    if (id == NULL) {
+        return SSH_ERROR;
+    }
+
+    *value = strdup(id);
+    if (*value == NULL) {
+        ssh_set_error_oom(session);
+        return SSH_ERROR;
+    }
+
+    return SSH_OK;
+}
+
 /**
  * @brief Tries to automatically authenticate with public key and "none"
  *