端口扫描应用开发：主机列表管理与命令实现

### 端口扫描应用开发：主机列表管理与命令实现 在开发端口扫描应用时，我们需要实现主机列表管理的功能。下面将详细介绍如何创建主机列表管理的包、编写相关代码以及实现命令行工具的测试。 #### 1. 创建扫描包 首先，我们要创建一个名为 `scan` 的包来实现主机列表管理的业务逻辑。具体操作步骤如下： 1. 进入应用的根目录，创建 `scan` 目录并切换到该目录： ```bash $ cd $HOME/pragprog.com/rggo/cobra/pScan $ mkdir scan $ cd scan ``` 2. 创建并编辑 `hostsList.go` 文件，定义包名和导入所需的包： ```go // Package scan provides types and functions to perform TCP port // scans on a list of hosts package scan import ( "bufio" "errors" "fmt" "io/ioutil" "os" "sort" ) ``` 3. 定义两个错误变量，分别表示主机已存在和主机不存在： ```go var ( ErrExists = errors.New("Host already in the list") ErrNotExists = errors.New("Host not in the list") ) ``` 4. 定义 `HostsList` 结构体来表示主机列表： ```go // HostsList represents a list of hosts to run port scan type HostsList struct { Hosts []string } ``` 5. 为 `HostsList` 结构体定义方法： - `search` 方法：用于在列表中搜索主机： ```go // search searches for hosts in the list func (hl *HostsList) search(host string) (bool, int) { sort.Strings(hl.Hosts) i := sort.SearchStrings(hl.Hosts, host) if i < len(hl.Hosts) && hl.Hosts[i] == host { return true, i } return false, -1 } ``` - `Add` 方法：用于向列表中添加主机： ```go // Add adds a host to the list func (hl *HostsList) Add(host string) error { if found, _ := hl.search(host); found { return fmt.Errorf("%w: %s", ErrExists, host) } hl.Hosts = append(hl.Hosts, host) return nil } ``` - `Remove` 方法：用于从列表中删除主机： ```go // Remove deletes a host from the list func (hl *HostsList) Remove(host string) error { if found, i := hl.search(host); found { hl.Hosts = append(hl.Hosts[:i], hl.Hosts[i+1:]...) return nil } return fmt.Errorf("%w: %s", ErrNotExists, host) } ``` - `Load` 方法：用于从文件中加载主机列表： ```go // Load obtains hosts from a hosts file func (hl *HostsList) Load(hostsFile string) error { f, err := os.Open(hostsFile) if err != nil { if errors.Is(err, os.ErrNotExist) { return nil } return err } defer f.Close() scanner := bufio.NewScanner(f) for scanner.Scan() { hl.Hosts = append(hl.Hosts, scanner.Text()) } return nil } ``` - `Save` 方法：用于将主机列表保存到文件中： ```go // Save saves hosts to a hosts file func (hl *HostsList) Save(hostsFile string) error { output := "" for _, h := range hl.Hosts { output += fmt.Sprintln(h) } return ioutil.WriteFile(hostsFile, []byte(output), 0644) } ``` #### 2. 编写测试用例 为了确保 `scan` 包的功能正常，我们需要编写测试用例。具体步骤如下： 1. 保存 `hostsList.go` 文件，创建并编辑 `hostsList_test.go` 文件，定义包名和导入所需的包： ```go package scan_test import ( "errors" "io/ioutil" "os" "testing" "pragprog.com/rggo/cobra/pScan/scan" ) ``` 2. 编写 `TestAdd` 函数来测试 `Add` 方法： ```go func TestAdd(t *testing.T) { testCases := []struct { name string host string expectLen int expectErr error }{ {"AddNew", "host2", 2, nil}, {"AddExisting", "host1", 1, scan.ErrExists}, } for _, tc := range testCases { t.Run(tc.name, func(t *testing.T) { hl := &scan.HostsList{} // Initialize list if err := hl.Add("host1"); err != nil { t.Fatal(err) } err := hl.Add(tc.host) if tc.expectErr != nil { if err == nil { t.Fatalf("Expected error, got nil instead\n") } if !errors.Is(err, tc.expectErr) { t.Errorf("Expected error %q, got %q instead\n", tc.expectErr, err) } return } if err != nil { t.Fatalf("Expected no error, got %q instead\n", err) } if len(hl.Hosts) != tc.expectLen { t.Errorf("Expected list length %d, got %d instead\n", tc.expectLen, len(hl.Hosts)) } if hl.Hosts[1] != tc.host { t.Errorf("Expected host name %q as index 1, got %q instead\n", tc.host, hl.Hosts[1]) } }) } } ``` 3. 编写 `TestRemove` 函数来测试 `Remove` 方法： ```go func TestRemove(t *testing.T) { testCases := []struct { name string host string expectLen int expectErr error }{ {"RemoveExisting", "host1", 1, nil}, {"RemoveNotFound", "host3", 1, scan.ErrNotExists}, } for _, tc := range testCases { t.Run(tc.name, func(t *testing.T) { hl := &scan.HostsList{} // Initialize list for _, h := range []string{"host1", "host2"} { if err := hl.Add(h); err != nil { t.Fatal(err) } } err := hl.Remove(tc.host) if tc.expectErr != nil { if err == nil { t.Fatalf("Expected error, got nil instead\n") } if !errors.Is(err, tc.expectErr) { t.Errorf("Expected error %q, got %q instead\n", tc.expectErr, err) } return } if err != nil { t.Fatalf("Expected no error, got %q instead\n", err) } if len(hl.Hosts) != tc.expectLen { t.Errorf("Expected list length %d, got %d instead\n", tc.expectLen, len(hl.Hosts)) } if hl.Hosts[0] == tc.host { t.Errorf("Host name %q should not be in the list\n", tc.host) } ```