Zhuang's Diary

言之有物，持之以恒

Posted on Edited on

Corda的共识容错能力较弱

Version 1～5，Corda会分享交易直接相关的前一笔交易信息，可以防止的错误包括：

  1. 前一笔交易的签名错误；
  2. 前一笔交易的金额错误；

不能够发现的错误包括：

  1. 前一笔交易双方共同伪造交易，用以欺骗第三方；
  2. 间隔多笔的伪造交易，用以欺骗第三方；
  3. 交易的排序由Kafka决定，或者如ABC均提出向D购买某资产，D可以不按照合约逻辑，或者时间顺序，而是按照D在规则外的某种喜好，来完成交易，进而欺骗其他参与方。

可能发生的效率问题：

  1. 如若某节点在接收到某交易时，想校验其前序交易，不仅仅是前一个交易，而是全部的前序交易，首先是及其困难的，而且随着链的增高，其校验时间也在升高。
  2. 即使增加校验节点，但并不能够解决上述问题。另外，校验节点的可信性，效率等都成为新的系统问题。

综上，针对需要区块链的共识机制来增强信任的场景，Corda不是一个好的选择。但是，如果在无需算法来建立信任（如工农中建四大行的某种资产交易系统，他们相互之间的欺诈风险非常低），而是需要某种账本系统，来减少对账摩擦的话，Corda可以帮助到企业，完成分别记账的任务。

参考：如上，多年的困惑，得到Corda的指导和确认，感谢。

Posted on Edited on

Terraform - https://www.terraform.io/

Terraform is a provisioning focus tool.

provisioning - 置备是创建和设置 IT 基础架构的过程，包括为管理用户和系统对各种资源访问权限所需执行的步骤。置备是部署服务器、应用、网络组件、存储、边缘设备等的早期阶段。

置备与配置管理 - configuration-management 不同，但它们都属于部署过程中的步骤。一旦置备了系统，下一步就是配置系统，并在一段时间内使其保持一致。

如何组合使用

  • Provisioning + Config management = Terraform + Ansible

  • Provisioning + Server Templating = Terraform + packer

  • Provisioning + Orchestration Tool = Terraform + kubernetes，通常在AWS中会使用EKS服务。

Terraform Architecture

如何编写Terraform的代码？

根据上图架构中，我们需要参考如下，AWS Provider 的文档，通过其中的代码，provisioning地构建AWS的IT基础设施。

https://registry.terraform.io/providers/hashicorp/aws/latest/docs

如何执行Terraform？

all terraform cli docs are here ==> https://developer.hashicorp.com/terraform/tutorials/cli

1.terraform init

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➜  02-overview git:(main) pwd
/Users/xxx/Documents/source_code/devops-directive-terraform-course/02-overview
➜  02-overview git:(main) ls
README.md main.tf
➜  02-overview git:(main) terraform -help  
Usage: terraform [global options] <subcommand> [args]

The available commands for execution are listed below.
The primary workflow commands are given first, followed by
less common or more advanced commands.

Main commands:
  init          Prepare your working directory for other commands
  validate      Check whether the configuration is valid
  plan          Show changes required by the current configuration
  apply         Create or update infrastructure
  destroy       Destroy previously-created infrastructure

All other commands:
  console       Try Terraform expressions at an interactive command prompt
  fmt           Reformat your configuration in the standard style
  force-unlock  Release a stuck lock on the current workspace
  get           Install or upgrade remote Terraform modules
  graph         Generate a Graphviz graph of the steps in an operation
  import        Associate existing infrastructure with a Terraform resource
  login         Obtain and save credentials for a remote host
  logout        Remove locally-stored credentials for a remote host
  metadata      Metadata related commands
  output        Show output values from your root module
  providers     Show the providers required for this configuration
  refresh       Update the state to match remote systems
  show          Show the current state or a saved plan
  state         Advanced state management
  taint         Mark a resource instance as not fully functional
  test          Experimental support for module integration testing
  untaint       Remove the 'tainted' state from a resource instance
  version       Show the current Terraform version
  workspace     Workspace management

Global options (use these before the subcommand, if any):
  -chdir=DIR    Switch to a different working directory before executing the
                given subcommand.
  -help         Show this help output, or the help for a specified subcommand.
  -version      An alias for the "version" subcommand.
➜  02-overview git:(main) terraform init 

Initializing the backend...

Initializing provider plugins...
- Finding hashicorp/aws versions matching "~> 3.0"...
- Installing hashicorp/aws v3.76.1...
- Installed hashicorp/aws v3.76.1 (signed by HashiCorp)

Terraform has created a lock file .terraform.lock.hcl to record the provider
selections it made above. Include this file in your version control repository
so that Terraform can guarantee to make the same selections by default when
you run "terraform init" in the future.

Terraform has been successfully initialized!

You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.

If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your working directory. If you forget, other
commands will detect it and remind you to do so if necessary.

➜  02-overview git:(main) tree
.
|____main.tf
|____.terraform
| |____providers
| | |____registry.terraform.io
| | | |____hashicorp
| | | | |____aws
| | | | | |____3.76.1
| | | | | | |____darwin_arm64
| | | | | | | |____terraform-provider-aws_v3.76.1_x5
|____README.md
|____.terraform.lock.hcl

2.terraform plan

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# terraform plan
An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # aws_instance.example will be created
  + resource "aws_instance" "example" {
      + ami                          = "ami-0829e595217a759b9"
      + arn                          = (known after apply)
           + tags                         = {
          + "Name"  = "int32bit-test-ft"
          + "Owner" = "int32bit"
        }
      + vpc_security_group_ids       = (known after apply)
      + ...

Plan: 1 to add, 0 to change, 0 to destroy.

3.terraform apply

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# terraform apply
Plan: 1 to add, 0 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

aws_instance.example: Creating...
aws_instance.example: Still creating... [10s elapsed]
aws_instance.example: Still creating... [20s elapsed]
aws_instance.example: Creation complete after 20s [id=i-0bb96d24b6e6d37eb]

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

4.terraform destroy

5.adfs

在实际企业环境中，aws 的使用通常是需要多重身份验证的，所以多数使用 ADFS (multi factor authentication with active directory)。

其中最常用的工具是 https://github.com/venth/aws-adfs，通过 证书 / 身份（如SSO）/ 密码 登陆aws，terraform也是如此。

实际项目结构

而且，在复杂的系统部署中，可以针对每一个module的tf中，添加 shell 脚本，如针对compute.tf单独运行的shell脚本，让每一个脚本（手动）执行，即每一terraform部署完成后，确认执行结果。分步骤地，解耦地完成复杂系统的部署工作，切能够按照企业要求，完成安全，网络，EKS等规则要求。

Reference

all terraform providers ==> https://registry.terraform.io/browse/providers

terraform Course ==> https://www.youtube.com/watch?v=7xngnjfIlK4&t=8s

Posted on
Feature Golang database/sql GORM SQLC SQLX
Type Standard library ORM library Code generation tool Library extension
Ease of use Low - manual mapping SQL fields to variables High Medium Medium
SQL Abstraction None High Medium (Type-safe SQL) Low
Query Building No Yes No Yes
Automatic Struct Mapping No Yes Yes Yes
Type Safety No Yes Yes No
Supported Databases Any (with driver) MySQL, PostgreSQL, SQLite, SQL Server PostgreSQL, MySQL, SQLite Any (with driver)
Learning Curve Low Medium Medium Low
External Dependency No Yes Yes Yes
Performance on high load High Low High High
Code generation No No Yes - Catch SQL query errors before generating codes Yes - Failure won’t occur until runtime

SQLC + migrate is the prefect choice if the database is PostgreSQL.

This is the detail guide movie here ==> https://www.youtube.com/watch?v=0CYkrGIJkpw (Generate CRUD Golang code from SQL | Compare db/sql, gorm, sqlx & sqlc)

Posted on

问题描述

早期空头 NFT/ERC20 Token 的话，更多需要用户来做 withdraw。本文章的设计模式是由发行方来发送 NFT/ERC20 Token 给到用户。同样适用于多个资产同时转账的场景。

解决方案

合约接口：

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pragma solidity ^0.8.0;

interface IMulticall {
    /// @notice           Takes an array of abi-encoded call data, delegatecalls itself with each calldata, and returns the abi-encoded result
    /// @dev              Reverts if any delegatecall reverts
    /// @param    data    The abi-encoded data
    /// @returns  results The abi-encoded return values
    function multicall(bytes[] calldata data) external virtual returns (bytes[] memory results);

    /// @notice           OPTIONAL. Takes an array of abi-encoded call data, delegatecalls itself with each calldata, and returns the abi-encoded result
    /// @dev              Reverts if any delegatecall reverts
    /// @param    data    The abi-encoded data
    /// @param    values  The effective msg.values. These must add up to at most msg.value
    /// @returns  results The abi-encoded return values
    function multicallPayable(bytes[] calldata data, uint256[] values) external payable virtual returns (bytes[] memory results);
}

multicallPayable 是可选的，因为由于 msg.value，它并不总是可行的。

以下是最为简陋的实现方式。

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pragma solidity ^0.8.0;

/// Derived from OpenZeppelin's implementation
abstract contract Multicall is IMulticall {
    function multicall(bytes[] calldata data) external virtual returns (bytes[] memory results) {
        results = new bytes[](data.length);
        for (uint256 i = 0; i < data.length; i++) {
            (bool success, bytes memory returndata) = address(this).delegatecall(data);
            require(success);
            results[i] = returndata;
        }
        return results;
    }
}

multicallPayable 只应在合约能够支持时使用。以上实现可能允许攻击者使用相同的以太币多次调用支付函数。

调用方法/测试方法

以下 JavaScript 代码使用 Ethers 库，应自动将 ERC-20 Token 的 amt 单位传输到地址 A 和地址 B。

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await token.multicall(await Promise.all([
    token.interface.encodeFunctionData('transfer', [ addressA, amt ]),
    token.interface.encodeFunctionData('transfer', [ addressB, amt ]),
]));

完整工程

如下：

https://github.com/willzhuang/multicall

https://github.com/ethereum/EIPs/blob/master/EIPS/eip-6357.md