feat(admin): add administrator sessions

admin/internal/server/router.go

@@ -2,18 +2,164 @@
 package server
 
 import (
+	"crypto/subtle"
+	"errors"
 	"net/http"
+	"net/url"
+	"strings"
+
+	"cmbuyer/admin/internal/auth"
+	"cmbuyer/admin/internal/transport/webui"
 
 	"github.com/gin-gonic/gin"
+	"golang.org/x/crypto/bcrypt"
 )
 
-// NewRouter 返回当前服务范围内的完整 HTTP 路由。
-func NewRouter() *gin.Engine {
-	router := gin.New()
+const maxFormBytes = 8 << 10
 
-	router.GET("/healthz", func(context *gin.Context) {
-		context.JSON(http.StatusOK, gin.H{"status": "ok"})
-	})
+// Options 是路由层需要的安全依赖。凭据由启动配置注入，不能在路由中设置默认值。
+type Options struct {
+	AdminUsername       string
+	AdminPasswordBcrypt string
+	Sessions            *auth.Manager
+}
 
-	return router
+// NewRouter 返回当前服务范围内的完整 HTTP 路由。
+func NewRouter(options Options) (*gin.Engine, error) {
+	if options.AdminUsername == "" || options.AdminPasswordBcrypt == "" || options.Sessions == nil {
+		return nil, errors.New("server authentication options are incomplete")
+	}
+
+	router := gin.New()
+	router.Use(gin.Recovery())
+	router.Use(securityHeaders())
+	router.GET("/healthz", healthz)
+	router.GET("/login", loginPage(options))
+	router.POST("/login", login(options))
+	router.POST("/logout", logout(options))
+	router.GET("/tasks", tasksPage(options))
+
+	return router, nil
+}
+
+func healthz(context *gin.Context) {
+	context.JSON(http.StatusOK, gin.H{"status": "ok"})
+}
+
+func securityHeaders() gin.HandlerFunc {
+	return func(context *gin.Context) {
+		context.Header("Cache-Control", "no-store")
+		context.Header("X-Content-Type-Options", "nosniff")
+		context.Header("Referrer-Policy", "no-referrer")
+		context.Header("Content-Security-Policy", "default-src 'self'; style-src 'self' 'unsafe-inline'; script-src 'none'; object-src 'none'; base-uri 'none'; frame-ancestors 'none'; form-action 'self'")
+		context.Next()
+	}
+}
+
+func loginPage(options Options) gin.HandlerFunc {
+	return func(context *gin.Context) {
+		csrfToken, authenticated := options.Sessions.Ensure(context.Writer, context.Request)
+		if authenticated {
+			context.Redirect(http.StatusSeeOther, "/tasks")
+			return
+		}
+
+		renderLogin(context, http.StatusOK, csrfToken, returnTo(context.Query("return_to")), "", "")
+	}
+}
+
+func login(options Options) gin.HandlerFunc {
+	return func(context *gin.Context) {
+		limitFormBody(context)
+		csrfToken := context.PostForm("csrf_token")
+		returnPath := returnTo(context.PostForm("return_to"))
+		username := context.PostForm("username")
+		password := context.PostForm("password")
+
+		if _, ok := options.Sessions.VerifyCSRF(context.Request, csrfToken); !ok {
+			newCSRF, _ := options.Sessions.Ensure(context.Writer, context.Request)
+			renderLogin(context, http.StatusForbidden, newCSRF, returnPath, "", "请求已过期，请重新登录。")
+			return
+		}
+
+		usernameMatches := subtle.ConstantTimeCompare([]byte(options.AdminUsername), []byte(username)) == 1
+		passwordMatches := bcrypt.CompareHashAndPassword([]byte(options.AdminPasswordBcrypt), []byte(password)) == nil
+		if !usernameMatches || !passwordMatches {
+			csrf, _ := options.Sessions.Ensure(context.Writer, context.Request)
+			renderLogin(context, http.StatusUnauthorized, csrf, returnPath, "", "账号或密码不正确，请检查后重试。")
+			return
+		}
+
+		options.Sessions.RotateAuthenticated(context.Writer, context.Request)
+		context.Redirect(http.StatusSeeOther, returnPath)
+	}
+}
+
+func logout(options Options) gin.HandlerFunc {
+	return func(context *gin.Context) {
+		limitFormBody(context)
+		authenticated, ok := options.Sessions.VerifyCSRF(context.Request, context.PostForm("csrf_token"))
+		if !ok || !authenticated {
+			context.Status(http.StatusForbidden)
+			return
+		}
+
+		options.Sessions.Logout(context.Writer, context.Request)
+		context.Redirect(http.StatusSeeOther, "/login")
+	}
+}
+
+func tasksPage(options Options) gin.HandlerFunc {
+	return func(context *gin.Context) {
+		csrfToken, authenticated := options.Sessions.Ensure(context.Writer, context.Request)
+		if !authenticated {
+			context.Redirect(http.StatusSeeOther, "/login?return_to="+url.QueryEscape(context.Request.URL.RequestURI()))
+			return
+		}
+
+		context.Header("Content-Type", "text/html; charset=utf-8")
+		if err := webui.RenderTasks(context.Writer, webui.TasksData{CSRFToken: csrfToken}); err != nil {
+			_ = context.Error(err)
+		}
+	}
+}
+
+func renderLogin(context *gin.Context, status int, csrfToken, returnPath, username, message string) {
+	context.Header("Content-Type", "text/html; charset=utf-8")
+	context.Status(status)
+	if err := webui.RenderLogin(context.Writer, webui.LoginData{
+		CSRFToken: csrfToken,
+		ReturnTo:  returnPath,
+		Username:  username,
+		Error:     message,
+	}); err != nil {
+		_ = context.Error(err)
+	}
+}
+
+func limitFormBody(context *gin.Context) {
+	context.Request.Body = http.MaxBytesReader(context.Writer, context.Request.Body, maxFormBytes)
+}
+
+func returnTo(value string) string {
+	if value == "/tasks" || strings.HasPrefix(value, "/tasks/") || strings.HasPrefix(value, "/tasks?") {
+		if strings.Contains(value, "\\") || strings.Contains(value, "%") || strings.HasPrefix(value, "//") {
+			return "/tasks"
+		}
+		parsed, err := url.ParseRequestURI(value)
+		if err == nil && parsed.IsAbs() == false && parsed.Host == "" && hasSafeTaskPath(parsed.Path) {
+			return value
+		}
+	}
+
+	return "/tasks"
+}
+
+func hasSafeTaskPath(path string) bool {
+	for _, segment := range strings.Split(path, "/") {
+		if segment == "." || segment == ".." {
+			return false
+		}
+	}
+	return true
 }