Sputnik DAO工廠合約解讀

1. Sputnik-DAO工廠合約

Sputnik-DAO採用創建型工廠設計模式實現了該平台下去中心化自治組織(DAO)的統一創建與管理。

本文將詳細介紹Sputnik-DAO平台工廠模式(sputnikdao-factory)的設計實現。

對應合約的原始碼倉庫位於:

2. DAPP模塊功能介紹

Sputnik DAO平台的DAPP頁面已有不少去中心化自治組織創建並定制了屬於自己的DAO實例對象(Sputnikdaov2合約)。

截至2022年3月,該平台下創建最活躍的DAO爲news.sputnik-dao.near,其中已有3051個提案(proposals)正在公開投票中或狀態已結。

通過NEAR Explorer探索可發現,該平台各DAO實例合約由NEAR帳戶sputnik-dao.near(sputnikdao-factory合約)統一部署。

即所有基於Sputnik DAO平台創建的DAO實例合約分別被部署在該NEAR帳戶的子帳戶下,例如:

• pcp.sputnik-dao.near
• test-dao-bro.sputnik-dao.near
• blaqkstereo.sputnik-dao.near
• octopode-dao.sputnik-dao.near

去中心化組織可在NEAR主網中公開發起交易,通過調用sputnikdao-factory合約所提供的create()方法,創建新的DAO實例。

3. sputnikdao-factory合約代碼解讀

3.1 創建DAO

sputnikdao-factory合約狀態主要由如下兩個部分組成:

rust pub struct SputnikDAOFactory { factory_manager: FactoryManager, daos: UnorderedSet, }

• factory_manager:合約主要的內部功能邏輯實現,提供了一系列創建/刪除/更新DAO實例的方法。

• daos:採用集合數據結構,記錄了該平台歷史上所有已創建DAO實例的NEAR帳戶地址。

創建DAO實例所使用的sputnikdao-factory合約方法create()定義如下:

rust #[payable] pub fn create(&mut self, name: AccountId, args: Base64VecU8) { let account_id: AccountId = format!('{}.{}', name, env::current_account_id()) .parse() .unwrap(); let callback_args = serde_json::to_vec(&json!({ 'account_id': account_id, 'attached_deposit': U128(env::attached_deposit()), 'predecessor_account_id': env::predecessor_account_id() })) .expect('Failed to serialize'); self.factory_manager.create_contract( self.get_default_code_hash(), account_id, 'new', &args.0, 'on_create', &callback_args, ); }

factory_manager.create_contract的具體實現:

rust pub fn create_contract( &self, code_hash: Base58CryptoHash, account_id: AccountId, new_method: &str, args: &[u8], callback_method: &str, callback_args: &[u8], ) { let code_hash: CryptoHash = code_hash.into(); let attached_deposit = env::attached_deposit(); let factory_account_id = env::current_account_id().as_bytes().to_vec(); let account_id = account_id.as_bytes().to_vec(); unsafe { // Check that such contract exists. assert_eq!( sys::storage_has_key(code_hash.len() as _, code_hash.as_ptr() as _), 1, 'Contract doesn't exist' ); // Load input (wasm code) into register 0. sys::storage_read(code_hash.len() as _, code_hash.as_ptr() as _, 0); // schedule a Promise tx to account_id let promise_id = sys::promise_batch_create(account_id.len() as _, account_id.as_ptr() as _); // create account first. sys::promise_batch_action_create_account(promise_id); // transfer attached deposit. sys::promise_batch_action_transfer(promise_id, &attached_deposit as *const u128 as _); // deploy contract (code is taken from register 0). sys::promise_batch_action_deploy_contract(promise_id, u64::MAX as _, 0); // call new with given arguments. sys::promise_batch_action_function_call( promise_id, new_method.len() as _, new_method.as_ptr() as _, args.len() as _, args.as_ptr() as _, &NO_DEPOSIT as *const u128 as _, CREATE_CALL_GAS.0, ); // attach callback to the factory. let _ = sys::promise_then( promise_id, factory_account_id.len() as _, factory_account_id.as_ptr() as _, callback_method.len() as _, callback_method.as_ptr() as _, callback_args.len() as _, callback_args.as_ptr() as _, &NO_DEPOSIT as *const u128 as _, ON_CREATE_CALL_GAS.0, ); sys::promise_return(promise_id); } }

回調函數on_create的內部代碼實現:

rust #[private] pub fn on_create( &mut self, account_id: AccountId, attached_deposit: U128, predecessor_account_id: AccountId, ) -> bool { if near_sdk::is_promise_success() { self.daos.insert(&account_id); true } else { Promise::new(predecessor_account_id).transfer(attached_deposit.0); false } }

3.2 更新DAO

工廠合約所提供的合約接口update():

rust /// Tries to update given account created by this factory to the specified code. pub fn update(&self, account_id: AccountId, code_hash: Base58CryptoHash) { let caller_id = env::predecessor_account_id(); assert!( caller_id == self.get_owner() || caller_id == account_id, 'Must be updated by the factory owner or the DAO itself' ); assert!( self.daos.contains(&account_id), 'Must be contract created by factory' ); self.factory_manager .update_contract(account_id, code_hash, 'update'); }

factory_manager.update_contract()處理細節:

rust /// Forces update on the given contract. /// Contract must support update by factory for this via permission check. pub fn update_contract( &self, account_id: AccountId, code_hash: Base58CryptoHash, method_name: &str, ) { let code_hash: CryptoHash = code_hash.into(); let account_id = account_id.as_bytes().to_vec(); unsafe { // Check that such contract exists. assert!(env::storage_has_key(&code_hash), 'Contract doesn't exist'); // Load the hash from storage. sys::storage_read(code_hash.len() as _, code_hash.as_ptr() as _, 0); // Create a promise toward given account. let promise_id = sys::promise_batch_create(account_id.len() as _, account_id.as_ptr() as _); // Call update method, which should also handle migrations. sys::promise_batch_action_function_call( promise_id, method_name.len() as _, method_name.as_ptr() as _, u64::MAX as _, 0, &NO_DEPOSIT as *const u128 as _, (env::prepaid_gas() - env::used_gas() - GAS_UPDATE_LEFTOVER).0,); sys::promise_return(promise_id); } }

4. Sputnik-DAO Factory合約安全性分析

Sputnik-DAO Factory合約的安全性主要從如下幾個方面進行保證:

• 權限控制:合約開放的view類方法,不應修改合約的狀態變量,即方法定義中的第一個參數需設置爲&self,而非&mut self。

• 權限控制:合約開放的特權函數,這些函數只能由合約owner(或DAO合約帳戶)執行,並在方法中存在相應的assertion。

• 錯誤處理:Sputnik-DAO Factory合約對可能發生的異常情況都實現了相應合理的錯誤處理機制。例如用戶使用Factory合約創建新DAO實例合約最後會檢查創建所有的步驟時候都已正常完整地執行,否則不應對用戶造成損失。