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[EOS源码分析] EOS智能合约开发实践之合约调用合约(inline action)

首先,目前dawn-4.1, dawn-4.2使用inline action是会报如下错误

transaction declares authority '{"actor":"hello.code","permission":"active"}', but does not have signatures for it under a provided delay of 0 ms

这个问题是4.0以后inline action的权限发生变化导致的。这个改动在eos官网的#3013这个issue讨论BM有提到过

核心是为智能合约账号添加eosio.code permission,比如hello.code调用hello.target智能合约,需要添加如下permission

cleos set account permission args.user active '{"threshold": 1,"keys": [{"key":"EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV", "weight":1}],"accounts": [{"permission":{"actor":"hello.code","permission":"eosio.code"},"weight":1}]}' owner -p args.user@owner

代码

新建两个contract: hello.code和hello.target

  • hello.target代码如下

     #include <eosiolib/eosio.hpp>
     #include <eosiolib/print.hpp>
     using namespace eosio;
    
     class target : public eosio::contract {
       public:
         using contract::contract;
    
         /// @abi action 
         void callme( account_name user ) {
             require_auth(user);
             print( "Call me from, ", name{user} );
         }
     };
    
     EOSIO_ABI( target, (callme) )
  • hello.code的代码:

     class hello : public eosio::contract {
       public:
         using contract::contract;
         /// @abi action
         void hi( account_name from, account_name to) {
             require_auth(from);
             print( "Hello, from:", name{from}, ", to:", name{to});
             action(
                 //这里{to, active}必须授权给{_self, eosio.code}
                 permission_level{to, N(active)},
                 //调用 hello.target合约 的'callme' action
                 N(hello.target), N(callme),
                 std::make_tuple(to)
              ).send();
         }
     };

    核心就是上面的红色字体的内容action(xx).send(),具体参数的含义是:

    Action(permssion_level, other_contract_account_name, method, args)

    所以:

    action(permission_level{to, N(active)},
            N(hello.target), N(callme), 
            std::make_tuple(to)
    ).send();

    这个等价于如下命令

    $cleos push action hello.target callme '["to"]' -p to

    测试

    $cleos create account eosio hello.code $KEY_PUB_1 $KEY_PUB_1
    $cleos set contract hello.code ./hello -p hello.code
    $cleos create account eosio args.user $KEY_PUB_2 $KEY_PUB_2
    $cleos create account eosio hello.target $KEY_PUB_3 $KEY_PUB_3
    $cleos create account eosio args.user1 $KEY_PUB_4 $KEY_PUB_4
    $cleos set contract hello.target ./hello.target -p hello.target
    $cleos set account permission args.user1 active '{"threshold": 1,"keys": [],"accounts": [{"permission":{"actor":"hello.code","permission":"eosio.code"},"weight":1}]}' owner -p args.user1@owner
    $cleos push action hello.code hi '["args.user", "args.user1"]' -p args.user

    源码一键实践

    https://github.com/itleaks/eos-contract/tree/master/callcontract-exp

    转载自:http://blog.csdn.net/itleaks

[EOS源码分析] EOS特殊智能合约eosio

这里说的eosio智能合约不是泛指eos的智能合约,它是一个特殊的具体的合约。它本事可大了,我们一起来看看它有哪些功能

负责智能合约部署

$ cleos set contract hello.code ../eos-contract/hello -p hello.code
Publishing contract...
executed transaction: daabe65267af4b9a11e5ff90a165bbaac68469630f499bcea1ef0eb7da6d970c  1792 bytes  2558 us
#         eosio <= eosio::setcode               {"account":"hello.code","vmtype":0,"vmversion":0,"code":"0061736d01000000013b0c60027f7e006000017e600...
#         eosio <= eosio::setabi                {"account":"hello.code","abi":"00010c6163636f756e745f6e616d65046e616d6501026869000104757365720c61636...

注意下 eosio <= eosio::setcodeeosio <= eosio::setabi
这段log很明显的说明了

$ cleos set contract eosio build/contracts/eosio.bios -p eosio

等价于调用eosio智能合约的setcode和setabi函数

$ cleos push action eosio setcode '[eosio.bios.wasm]' -p eosio
$ cleos push action eosio setabi eosio '[eosio.bios.abi] -p eosio

也就说合约部署是通过调用eosio合约来实现的
对应的源码:
set contract会产生setcode和setabi两个action

add_standard_transaction_options(contractSubcommand, "account@active");
   add_standard_transaction_options(codeSubcommand, "account@active");
   add_standard_transaction_options(abiSubcommand, "account@active");
   contractSubcommand->set_callback([&] {
      shouldSend = false;
      set_code_callback();
      set_abi_callback();
      std::cout << localized("Publishing contract...") << std::endl;
      send_actions(std::move(actions), 10000, packed_transaction::zlib);
   });

chain::action create_setcode(const name& account, const bytes& code) {
   return action {
      tx_permission.empty() ? vector<chain::permission_level>{{account,config::active_name}} : get_account_permissions(tx_permission),
      setcode{
         .account   = account,
         .vmtype    = 0,
         .vmversion = 0,
         .code      = code
      }
   };
}

struct setcode {
   account_name                     account;
   uint8_t                          vmtype = 0;
   uint8_t                          vmversion = 0;
   bytes                            code;

   static account_name get_account() {
      return config::system_account_name;
   }

   static action_name get_name() {
      return N(setcode);
   }
};

const static uint64_t system_account_name    = N(eosio);

set_code和set_abi都是通过调用system_account_name即eosio智能合约来执行的

负责账号创建

同样我们看看create account,其实就是调用eosio合约的newaccount函数

$ cleos create account eosio hello.code EOS7KBTMkUq4VPakqsZUnZfBbMbS2U7cn9qSa3q6G5ZzEeUeNSVgv EOS7KBTMkUq4VPakqsZUnZfBbMbS2U7cn9qSa3q6G5ZzEeUeNSVgv
executed transaction: 01aff4356a6277eec777494fc6aeaf97164c53997c46fe853247ed7e100f4987  200 bytes  911 us
#         eosio <= eosio::newaccount            {"creator":"eosio","name":"hello.code","owner":{"threshold":1,"keys":[{"key":"EOS7KBTMkUq4VPakqsZUnZ...

负责权限管理

这次是调用eosio的updateauth函数

$ cleos set account permission testaccount active '{"threshold" : 1, "keys" : [], "accounts" : [{"permission":{"actor":"bob","permission":"active"},"weight":1}, {"permission":{"actor":"stacy","permission":"active"},"weight":1}]}’ owner
executed transaction: b1bc9680a9ba615a6de8c3f7c692d7d28ff97edae245bb40f948692b14ea6c15  160 bytes  189 us
#         eosio <= eosio::updateauth            {"account":"testaccount","permission":"active","parent":"owner","auth":{"threshold":1,"keys":[],"acc...
warning: transaction executed locally, but may not be confirmed by the network yet

蛋生鸡,鸡生蛋问题

既然eosio是一个智能合约,而它又负责合约部署,那它自己是谁部署的呢?我们先来看下这个结构图

eosio contract负责系统服务,比如部署合约,创建账号。infra contracts层比如eosio.token和eosio.msig类似库作用的合约,比如多签名,发行代币,方便dapp层使用。Dapp才是用户直接接触的,每个开发人员编写程序然后部署,这些程序都是DApp。

eosio contract由3个部分构成
  • nativeaction
    nativeactions就是前面提到的setcode, setabi, newaccount功能的函数集。这部分代码是hardcode在EOS系统代码里的,也就说不需要部署这一步骤,所以就解决了蛋生鸡,鸡生蛋问题。
  • eosio.bios, eosio.system
    eosio.bios是一个智能合约的代码,是通过智能合约部署方式绑定到eosio contract上的。那你可能会说,eosio.bios部署后,nativeactions部分是不是就失效了啊。确实可以这样实现,由于setcode这些action需要永久生效,这就需要eosio.bios包含nativeactions这些函数,这样就出现了相同一份代码分散在两个模块,独立性和维护不够好。所以,目前的实现是通过特殊处理让nativeactions的函数有最高优先级,永不覆盖,哪怕eosio.bios实现了同样的函数(比如set_code, set_abi)。但是eosio.system和eosio.bios是一个级别的,都是contract, 是水火不相容的,一旦将eosio.system绑定到eosio这个账号,eosio.bios就失效了,所以eosio.bios的函数要么是临时用途的,要么就需要bios.system重新实现,比如setalimits会失效,而setpriv会在eosio.system重新实现。这个和cpu启动一样,一开始bios(bootloader)代码运行,然后引导system代码,当system加载后,bios(bootloader)代码失效。所以从这个设计和名字可以看出,EOS确实是在按照操作系统的逻辑设计。
    eosio.bios的接口
    EOSIO_ABI( eosio::bios, (setpriv)(setalimits)(setglimits)(setprods)(reqauth) )

    eosio.sytem的接口

    EOSIO_ABI( eosiosystem::system_contract,
    (setram)
    // delegate_bandwith.cpp
    (delegatebw)(undelegatebw)(refund)
    (buyram)(buyrambytes)(sellram)
    // voting.cpp
    // producer_pay.cpp
    (regproxy)(regproducer)(unregprod)(voteproducer)
    (claimrewards)
    // native.hpp
    (onblock)
    (newaccount)(updateauth)(deleteauth)(linkauth)(unlinkauth)(postrecovery)(passrecovery)(vetorecovery)(onerror)(canceldelay)
    //this file
    (setpriv)
    )

nativeaction解读

  • nativeaction注册
    nativeaction是通过SET_APP_HANDLER注册的

    #define SET_APP_HANDLER( receiver, contract, action) \
     set_apply_handler( #receiver, #contract, #action, &BOOST_PP_CAT(apply_, BOOST_PP_CAT(contract, BOOST_PP_CAT(_,action) ) ) )
    
     SET_APP_HANDLER( eosio, eosio, newaccount );
     SET_APP_HANDLER( eosio, eosio, setcode );
     SET_APP_HANDLER( eosio, eosio, setabi );
     SET_APP_HANDLER( eosio, eosio, updateauth );
     SET_APP_HANDLER( eosio, eosio, deleteauth );
     SET_APP_HANDLER( eosio, eosio, linkauth );
     SET_APP_HANDLER( eosio, eosio, unlinkauth );
    /*
     SET_APP_HANDLER( eosio, eosio, postrecovery );
     SET_APP_HANDLER( eosio, eosio, passrecovery );
     SET_APP_HANDLER( eosio, eosio, vetorecovery );
    */
    
     SET_APP_HANDLER( eosio, eosio, canceldelay );
     void set_apply_handler( account_name receiver, account_name contract, action_name action, apply_handler v ) {
        apply_handlers[receiver][make_pair(contract,action)] = v;
     }

    对应的函数名是apply_eosio_xxx,比如apply_eosio_setcode,apply_eosio_newaccount

  • nativeaction函数调用
    系统会先检测action的名字是否注册在native handler里,如果在则直接调用,不在的话,执行合约代码,并跳转到相应的action函数

      class apply_context { 
          { 
          public:
            apply_context(controller& con, transaction_context& trx_ctx, const action& a, uint32_t depth=0)
            :control(con)
            ,db(con.db())
            ,trx_context(trx_ctx)
            ,act(a)
            //合约的账号
            ,receiver(act.account)
            ,used_authorizations(act.authorization.size(), false)
      }
    
      action_trace apply_context::exec_one()
      {
         auto start = fc::time_point::now();
    
         const auto& cfg = control.get_global_properties().configuration;
         try {
            //获取智能合约对象
            const auto &a = control.get_account(receiver);
            privileged = a.privileged;
            //检测该action是否是native action,如果是则调用native handler
            auto native = control.find_apply_handler(receiver, act.account, act.name);
            if (native) {
               //hative handler(action)存在,则调用
               (*native)(*this);
            }
            //只要不是setcode调用,允许nativehandler和contract部署的代码都执行
            if( a.code.size() > 0
                && !(act.account == config::system_account_name && act.name == N(setcode) && receiver == config::system_account_name) ) {
               try {
                  control.get_wasm_interface().apply(a.code_version, a.code, *this);
               } catch ( const wasm_exit& ){}
            }
           ….
    
         } FC_CAPTURE_AND_RETHROW((_pending_console_output.str()));
      }
    转载自:http://blog.csdn.net/itleaks

[EOS源码分析] EOS编写HelloWorld智能合约

HelloWorld源码

#include <eosiolib/eosio.hpp>
#include <eosiolib/print.hpp>
using namespace eosio;

class hello : public eosio::contract {
  public:
      using contract::contract;

      /// @abi action 
      void hi( account_name user ) {
         print( "Hello, ", name{user} );
      }
};

EOSIO_ABI( hello, (hi) )

EOSIO_ABI是一个生成智能合约初始化函数apply的宏,生成的apply函数是智能合约的入口,它采用switch case的方式调用具体action对应的函数

#define EOSIO_ABI( TYPE, MEMBERS ) \
extern "C" { \
   void apply( uint64_t receiver, uint64_t code, uint64_t action ) { \
      auto self = receiver; \
      if( code == self ) { \
         TYPE thiscontract( self ); \
         switch( action ) { \
            EOSIO_API( TYPE, MEMBERS ) \
         } \
         /* does not allow destructor of thiscontract to run: eosio_exit(0); */ \
      } \
   } \
} \

编译

  • 生成wast文件
    $ eosiocpp -o hello.wast hello.cpp

    编译完成后,会生成两个新文件,hello.wast, hello.wasm
    .wast文件是wasm的代码文本格式,.wasm是汇编代码二级制格式

  • 生成abi文件
    eosiocpp -g hello.abi hello.cpp

部署智能合约

  • 创建新账号
    我们知道智能合约是附着在账号上的,因而需要为合约准备一个账号
    创建key并导入到钱包

    $ cleos create key
    Private key: 5JdchMrwMwD1PsZKCjpbaCQ4aJ3cFKzSWmCQfRzKCiGrDWds3PU
    Public key: EOS7KBTMkUq4VPakqsZUnZfBbMbS2U7cn9qSa3q6G5ZzEeUeNSVgv
    $ cleos wallet import 5JdchMrwMwD1PsZKCjpbaCQ4aJ3cFKzSWmCQfRzKCiGrDWds3PU

    以上面的key创建账号

    $ cleos create account eosio hello.code EOS7KBTMkUq4VPakqsZUnZfBbMbS2U7cn9qSa3q6G5ZzEeUeNSVgv EOS7KBTMkUq4VPakqsZUnZfBbMbS2U7cn9qSa3q6G5ZzEeUeNSVgv
    executed transaction: 9cdfd59700f8fb13b9a3b330d75f9e1d6a014d54f5bec21cee9afe35c8c49b99  200 bytes  5304 us
    #         eosio <= eosio::newaccount            {"creator":"eosio","name":"hello.code","owner":{"threshold":1,"keys":[{"key":"EOS7KBTMkUq4VPakqsZUnZ...
    warning: transaction executed locally, but may not be confirmed by the network yet
  • 将合约代码绑定到账号
    这里需要注意的是,xxx.wasm文件的目录必须是xxx,这里的hello.cpp, hello.wasm的目录就必须是hello,因为该命令会搜索xx/xx.wasm文件,这里会搜索hello/hello.wasm文件

    $ cleos set contract hello.code ./hello -p hello.code
    Reading WAST/WASM from ./hello/hello.wasm...
    Using already assembled WASM...
    Publishing contract...
    executed transaction: b26872e44b439ce289f7c449f959a7c9ad574045f69c53039ff365e79e1b8494  1800 bytes  5647 us
    #         eosio <= eosio::setcode               {"account":"hello.code","vmtype":0,"vmversion":0,"code":"0061736d01000000013b0c60027f7e006000017e600...
    #         eosio <= eosio::setabi                {"account":"hello.code","abi":"00010c6163636f756e745f6e616d650675696e74363401026869000104757365720c6...
    warning: transaction executed locally, but may not be confirmed by the network yet
  • 执行智能合约函数

    $ cleos push action hello.code hi '["args.user"]' -p args.user
    executed transaction: f694bfbc0c4d26751aa35a57bc1695fb24ff1a7606934dea64edd1e15f79664d  104 bytes  2444 us
    #    hello.code <= hello.code::hi               {"user":"args.user"}
    >> Hello, args.user

    智能合约权限检测实践

    前面的智能合约没有执行任何权限检测,因而在hi函数里新增一个权限检测

    class hello : public eosio::contract {
    public:
        using contract::contract;
    
        /// @abi action
        void hi( account_name user) {
           require_auth(user);
           print( "Hello, ", name{user} );
        }
    };

    红色字体的意思是执行"hi" action的权限必须是作为参数传进来的user
    如果使用hello.code账号执行则会报错

    $ cleos push action hello.code hi '["args.user"]' -p hello.code
    Error 3090004: missing required authority
    Ensure that you have the related authority inside your transaction!;
    If you are currently using 'cleos push action' command, try to add the relevant authority using -p option.
    Error Details:
    missing authority of args.user

    将参数换成hello.code执行成功

    $ cleos push action hello.code hi '["hello.code"]' -p hello.code
    executed transaction: 49db2db96c3719992af6e31d378385ac99ff611453ef81fd03cbcb822d223bd5  104 bytes  1752 us
    #    hello.code <= hello.code::hi               {"user":"hello.code"}
    >> Hello, hello.code
    warning: transaction executed locally, but may not be confirmed by the network yet

    源码一键实践

    https://github.com/itleaks/eos-contract下载源码,即可一键实践执行该智能合约

转载自:http://blog.csdn.net/itleaks

[EOS源码分析] EOS源码调试 (Mac OS)

编译带调试信息的EOS

编译可以调试(带源码信息)的EOS程序,增加-o Debug参数即可,即

$./eosio_build.sh -o Debug

下载VSCode

和比特币,以太坊源码调试一样,vscode是最佳的调试EOS源码的调试工具
下载地址https://code.visualstudio.com/Download

调试配置流程

导入源码

  • 配置调试文件
  • 执行后,会生成launch.json, 然后修改program字段值为对应的程序即可,比如要调试nodeos, 则修改为如下

    添加断点并开始调试

    在行号左边点击即可添加断点

    点击调试界面的右三角开始调试程序

    注意

    如果你曾经执行过release版本的nodeos,需要将数据清空,否则会报错
    database created by a different compiler, build, boost version, or operating system
    执行如下命令清空老数据
    $ rm -rf ~/Library/Application\ Support/eosio

    转载自:http://blog.csdn.net/itleaks

[EOS源码分析] EOS权限模型机制分析

cleos涉及account和contract的命令都会产生一个action,进而生成一个transaction,所有的action都需要指定permission权限
权限验证流程图如下

主要分为三个部分:

  • permission声明:1~3

  • permission授权证明:4~9

  • 权限检测:10~14,其中本地节点的nodeos和miner节点的nodeos都会执行权限检测,10~11(本地节点)和12~14(外部矿工节点)的工作内容是一样

    权限声明

    所有action相关命令都是通过通过-p/--permission声明permission参数,permission参数有几种表达形式:account, account@permission, publickey, account等价于account@active

    cleos create account -j eosio testaccount -p eosio@owner
    cleos set account permission testaccount active -p eosio@active
    cleos push action contractaccount method 'data' -p account@publish
    cleos push action contractaccount method1 'data' -p publickey

    如果用户没有输入该参数,cleos会自动添加默认permission,各种action的默认permission是不一样的

  • create account命令的默认permission是creator@active

  • set account permission命令的默认permission是account@active

  • push action contractaccount命令的默认permission是contractaccount@active

      chain::action create_newaccount(const name& creator, const name& newaccount, public_key_type owner, public_key_type active) {
         return action {
            //tx_permission就是-p参数的值,如果没有account@permission这个值,则默认为creater@active
            tx_permission.empty() ? vector<chain::permission_level>{{creator,config::active_name}} : get_account_permissions(tx_permission),
            eosio::chain::newaccount{
               .creator      = creator,
               .name         = newaccount,
               .owner        = eosio::chain::authority{1, {{owner, 1}}, {}},
               .active       = eosio::chain::authority{1, {{active, 1}}, {}}
            }
         };
      }
    
      chain::action create_updateauth(const name& account, const name& permission, const name& parent, const authority& auth) {
         return action { tx_permission.empty() ? vector<chain::permission_level>{{account,config::active_name}} : get_account_permissions(tx_permission),
                         updateauth{account, permission, parent, auth}};
      }

    如果-p account@permission只带了account,则默认为account@active

    vector<chain::permission_level> get_account_permissions(const vector<string>& permissions) {
     auto fixedPermissions = permissions | boost::adaptors::transformed([](const string& p) {
        vector<string> pieces;
        split(pieces, p, boost::algorithm::is_any_of("@"));
        //如果没有@permission这个声明,则默认为@active
        if( pieces.size() == 1 ) pieces.push_back( "active" );
        return chain::permission_level{ .actor = pieces[0], .permission = pieces[1] };
     });
     vector<chain::permission_level> accountPermissions;
     boost::range::copy(fixedPermissions, back_inserter(accountPermissions));
     return accountPermissions;
    }

    权限授权证明

    用户在执行cleos相关命令时通过-p声明了permission,这个permission只是一个字符串,谁都可以伪造的,因而需要提交真实可验证的证据,这个证据就是permission的授权(authority)信息。一个permission的authority可以是public key,也可以是子permission(另一个账号的permission, anotheraccount@permission), 这样就形成了一颗树, 叶子节点是public key, 只有该叶子节点的public key才有该权限。

    所以提交授权证明的过程由两部分构成

    收集权限permission的public key

    搜集permission生成的授权树的叶子节点的public key,即找出哪些public key被授予该权限
    比如上图的account@publish权限展开后得到如下叶子节点public key集合【key1, key10, key11, key20, key21, key60, key61】,只要用户拥有这些key集合中的一个public key对应的私钥就可以证明该用户可以以该account@publish权限提交action.

    cleos端:

      fc::variant push_transaction( signed_transaction& trx, int32_t extra_kcpu = 1000, packed_transaction::compression_type compression = packed_transaction::none ) {
         auto required_keys = determine_required_keys(trx);
      }
    
      fc::variant determine_required_keys(const signed_transaction& trx) {
         // TODO better error checking
         //wdump((trx));
         //拿到本地所有的public keys,这些key中可能拥有account@publish权限
         const auto& public_keys = call(wallet_url, wallet_public_keys);
         //trx包含action,action包含account@publish权限信息
         auto get_arg = fc::mutable_variant_object
                 ("transaction", (transaction)trx)
                 ("available_keys", public_keys);
         //调用keosd的服务获取本地满足account@publish权限的public key
         const auto& required_keys = call(get_required_keys, get_arg);
         return required_keys["required_keys"];
      }

    nodeos端:

    flat_set<public_key_type> authorization_manager::get_required_keys( const transaction& trx,
    const flat_set<public_key_type>& candidate_keys,
    fc::microseconds provided_delay)const
     {
        auto checker = make_auth_checker( [&](const permission_level& p){ return get_permission(p).auth; },
                                          _control.get_global_properties().configuration.max_authority_depth,
                                          candidate_keys,
                                          {},
                                          provided_delay,
                                          _noop_checktime
                                        );
    
        for (const auto& act : trx.actions ) {
           for (const auto& declared_auth : act.authorization) {
              //判断candidate_keys是否有合适的key被授予了act.authorization
              EOS_ASSERT( checker.satisfied(declared_auth), unsatisfied_authorization,
                          "transaction declares authority '${auth}', but does not have signatures for it.",
                          ("auth", declared_auth) );
           }
        }
        //返回满足条件的public key
        return checker.used_keys();
     }

    通过私钥签名提供授权证明

    搜索上一步收集到的public key,检测是否含有本用户的key,如果存在,则用相应的private key 签名交易,这样就可以证明该交易的具备account@publish这一permission

      fc::variant push_transaction( signed_transaction& trx, int32_t extra_kcpu = 1000, packed_transaction::compression_type compression = packed_transaction::none ) {
         //上一步获取到的被授权的public key
         auto required_keys = determine_required_keys(trx);
         if (!tx_skip_sign) {
            //通过签名交易提交permission证明
            sign_transaction(trx, required_keys);
         }
    
         if (!tx_dont_broadcast) {
            //广播交易
            return call(push_txn_func, packed_transaction(trx, compression));
         } else {
            return fc::variant(trx);
         }
      }
    
      void sign_transaction(signed_transaction& trx, fc::variant& required_keys) {
         // TODO determine chain id
         fc::variants sign_args = {fc::variant(trx), required_keys, fc::variant(chain_id_type{})};
         //cleos调用keosd的sign_trx api来执行签名操作
         const auto& signed_trx = call(wallet_url, wallet_sign_trx, sign_args);
         trx = signed_trx.as<signed_transaction>();
      }
    
      chain::signed_transaction
      wallet_manager::sign_transaction(const chain::signed_transaction& txn, const flat_set<public_key_type>& keys, const chain::chain_id_type& id) {
         check_timeout();
         chain::signed_transaction stxn(txn);
    
         for (const auto& pk : keys) {
            bool found = false;
            for (const auto& i : wallets) {
               if (!i.second->is_locked()) {
                  //根据public key拿到private key并签名,这个是没法伪造的
                  const auto& k = i.second->try_get_private_key(pk);
                  if (k) {
                     stxn.sign(*k, id);
                     found = true;
                     break; // inner for
                  }
               }
            }
         }
    
         return stxn;
      }

    节点验证权限授权证明

    用权限permission授权的私钥签名(授权证明)的交易发布到网络后,矿工收到该交易后,还需要解释签名并验证权限。验证分为两部分

  • 声明的权限是否满足action的最低权限要求

    transaction_trace_ptr push_transaction( const transaction_metadata_ptr& trx,
                                             fc::time_point deadline,
                                             bool implicit,
                                             uint32_t billed_cpu_time_us  )
     {
        FC_ASSERT(deadline != fc::time_point(), "deadline cannot be uninitialized");
    
        transaction_trace_ptr trace;
        try {
              if (!implicit) {
                 //检验权限和
                 authorization.check_authorization(
                         trx->trx.actions,
                         trx->recover_keys(),
                         {},
                         trx_context.delay,
                         [](){}
              }
    
        } FC_CAPTURE_AND_RETHROW((trace))
     } /// push_transaction
    
       //从签名里获取action发起者拥有的public key
        const flat_set<public_key_type>& recover_keys() {
           // TODO: Update caching logic below when we use a proper chain id setup for the particular blockchain rather than just chain_id_type()
           if( !signing_keys )
              signing_keys = trx.get_signature_keys( chain_id_type() );
           return *signing_keys;
        }
      void
         authorization_manager::check_authorization( const vector<action>&                actions,
                                                     const flat_set<public_key_type>&     provided_keys,
                                                     const 
      flat_set<permission_level>&    provided_permissions,
                                                    )const
         {
            map<permission_level, fc::microseconds> permissions_to_satisfy;
    
            for( const auto& act : actions ) {
               bool special_case = false;
               fc::microseconds delay = effective_provided_delay;
    
               if( act.account == config::system_account_name ) {
                  special_case = true;
                  //系统级action,比如修改权限的授权,链接授权等action,它的执行权限permission是固定的,需要在这里检测签名的keys是否具备相应的permission
                  if( act.name == updateauth::get_name() ) {
                     check_updateauth_authorization( act.data_as<updateauth>(), act.authorization );
                  } else if( act.name == deleteauth::get_name() ) {
                     check_deleteauth_authorization( act.data_as<deleteauth>(), act.authorization );
                  ……..
                  }
               }
    
               //authorization
               //其他action,检测授权是否正确
               for( const auto& declared_auth : act.authorization ) {
                  //对于上面的case,这里的declared_auth=account@publish
                  checktime();
    
                  if( !special_case ) {
                     //获取该action需要的最低权限
                     auto min_permission_name = lookup_minimum_permission(declared_auth.actor, act.account, act.name);
                     if( min_permission_name ) { // since special cases were already handled, it should only be false if the permission is eosio.any
                        //从区块中取出最低权限数据
                        const auto& min_permission = get_permission({declared_auth.actor, *min_permission_name});
                        //比较声明的权限是否满足最低权限
                        EOS_ASSERT( get_permission(declared_auth).satisfies( min_permission,
                                                                             _db.get_index<permission_index>().indices() ),
                                    irrelevant_auth_exception,
                                    "action declares irrelevant authority '${auth}'; minimum authority is ${min}",
                                    ("auth", declared_auth)("min", permission_level{min_permission.owner, min_permission.name}) );
                     }
                  }
    
         }

    声明的权限的授权签名是否正确

    void
     authorization_manager::check_authorization( const vector<action>&                actions,
                                                 const flat_set<public_key_type>&     provided_keys,
                                                 const flat_set<permission_level>&    provided_permissions,
                                                )const
     { 
       auto checker = make_auth_checker( [&](const permission_level& p){ return get_permission(p).auth; },
                                          _control.get_global_properties().configuration.max_authority_depth,
                                          provided_keys,
                                          provided_permissions,
                                          effective_provided_delay,
                                          checktime
                                        );
      …..
      for( const auto& p : permissions_to_satisfy ) {
           checktime(); // TODO: this should eventually move into authority_checker instead
           //验证
           EOS_ASSERT( checker.satisfied( p.first, p.second ), unsatisfied_authorization,
                       "transaction declares authority '${auth}', "
                       "but does not have signatures for it under a provided delay of ${provided_delay} ms",
                       ("auth", p.first)("provided_delay", provided_delay.count()/1000)
                       ("delay_max_limit_ms", delay_max_limit.count()/1000)
                     );
    
        }

    权限验证实例

    修改权限,命令如下:

    $cleos set account permission testaccount active '{"threshold" : 1, "keys" : [], "accounts" : [{"permission":{"actor":"bob","permission":"active"},"weight":1}, {"permission":{"actor":"stacy","permission":"active"},"weight":1}]}’ owner

    该命令没有添加permission参数,cleos会自动添加默认权限声明,其等价于

    $cleos set account permission testaccount active '{"threshold" : 1, "keys" : [], "accounts" : [{"permission":{"actor":"bob","permission":"active"},"weight":1}, {"permission":{"actor":"stacy","permission":"active"},"weight":1}]}’ owner
    -p testaccount@active

    -p testaccount@active是cleos自动补全的
    该action打包到transaction然后进入到了某一个矿工节点,然后就会执行上面的authorization_manager::check_authorization函数来验证权限,而对于该系统action,会调用check_updateauth_authorization来检验

    void authorization_manager::check_updateauth_authorization( const updateauth& update,
                                                                 const vector<permission_level>& auths
                                                               )const
     {
        EOS_ASSERT( auths.size() == 1, irrelevant_auth_exception,
                    "updateauth action should only have one declared authorization" );
        const auto& auth = auths[0];
        EOS_ASSERT( auth.actor == update.account, irrelevant_auth_exception,
                    "the owner of the affected permission needs to be the actor of the declared authorization" );
        //检测对应的permission是否存在
        const auto* min_permission = find_permission({update.account, update.permission});
        if( !min_permission ) { // creating a new permission
           //不存在则以父permission为min_permission检测
           min_permission = &get_permission({update.account, update.parent});
        }
        //示例中,testaccount.active存在,所以min_permission=testaccount@active
        //声明的也是testaccount@ative,所以能通过验证
        EOS_ASSERT( get_permission(auth).satisfies( *min_permission,
                                                    _db.get_index<permission_index>().indices() ),
                    irrelevant_auth_exception,
                    "updateauth action declares irrelevant authority '${auth}'; minimum authority is ${min}",
                    ("auth", auth)("min", permission_level{update.account, min_permission->name}) );
     }

    contract函数执行类型的action, 权限检测由contract代码激发,比如下面的例子

    void hi( account_name user ) {
     require_auth( user );
     print( "Hello, ", name{user} );
    }

    require_auth(user)就会激发对‘user@active’权限的检测

    转载自:http://blog.csdn.net/itleaks