started working on the backend

backend/pkg/router/router.go

@@ -0,0 +1,221 @@
+package router
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/golang-jwt/jwt/v5"
+	_config "github.com/johannesbuehl/golunteer/backend/pkg/config"
+	"github.com/johannesbuehl/golunteer/backend/pkg/db"
+	_logger "github.com/johannesbuehl/golunteer/backend/pkg/logger"
+)
+
+var logger = _logger.Logger
+var config = _config.Config
+
+var app *fiber.App
+
+// general message for REST-responses
+type responseMessage struct {
+	Status  int
+	Message string
+	Data    any
+}
+
+// answer the client request with the response-message
+func (result responseMessage) send(c *fiber.Ctx) error {
+	// if the status-code is in the error-region, return an error
+	if result.Status >= 400 {
+		// if available, include the message
+		if result.Message != "" {
+			return fiber.NewError(result.Status, result.Message)
+		} else {
+			return fiber.NewError(result.Status)
+		}
+	} else {
+		// if there is data, send it as JSON
+		if result.Data != nil {
+			c.JSON(result.Data)
+
+			// if there is a message, send it instead
+		} else if result.Message != "" {
+			c.SendString(result.Message)
+		}
+
+		return c.SendStatus(result.Status)
+	}
+}
+
+func init() {
+	// setup fiber
+	app = fiber.New(fiber.Config{
+		AppName:               "johannes-pv",
+		DisableStartupMessage: true,
+	})
+
+	// map with the individual methods
+	handleMethods := map[string]func(path string, handlers ...func(*fiber.Ctx) error) fiber.Router{
+		"GET":    app.Get,
+		"POST":   app.Post,
+		"PATCH":  app.Patch,
+		"DELETE": app.Delete,
+	}
+
+	// map with the individual registered endpoints
+	endpoints := map[string]map[string]func(*fiber.Ctx) responseMessage{
+		"GET":    {"events": getEvents},
+		"POST":   {},
+		"PATCH":  {},
+		"DELETE": {},
+	}
+
+	// handle specific requests special
+	app.Get("/api/welcome", handleWelcome)
+	app.Post("/api/login", handleLogin)
+	app.Get("/api/logout", handleLogout)
+
+	// register the registered endpoints
+	for method, handlers := range endpoints {
+		for address, handler := range handlers {
+			handleMethods[method]("/api/"+address, func(c *fiber.Ctx) error {
+				logger.Debug().Msgf("HTTP %s request: %q", c.Method(), c.OriginalURL())
+
+				return handler(c).send(c)
+			})
+		}
+	}
+}
+
+func Listen() {
+	// start the server
+	err := app.Listen(fmt.Sprintf(":%d", config.Server.Port))
+
+	fmt.Println(err)
+}
+
+func setSessionCookie(c *fiber.Ctx, jwt *string) {
+	var value string
+
+	if jwt == nil {
+		value = c.Cookies("session")
+	} else {
+		value = *jwt
+	}
+
+	c.Cookie(&fiber.Cookie{
+		Name:     "session",
+		Value:    value,
+		HTTPOnly: true,
+		SameSite: "strict",
+		MaxAge:   int(config.SessionExpire.Seconds()),
+	})
+}
+
+// removes the session-coockie from a request
+func removeSessionCookie(c *fiber.Ctx) {
+	c.Cookie(&fiber.Cookie{
+		Name:     "session",
+		Value:    "",
+		HTTPOnly: true,
+		SameSite: "strict",
+		Expires:  time.Unix(0, 0),
+	})
+}
+
+// payload of the JSON webtoken
+type JWTPayload struct {
+	UserID  int    `json:"userID"`
+	TokenID string `json:"tokenID"`
+}
+
+// complete JSON webtoken
+type JWT struct {
+	_config.Payload
+	CustomClaims JWTPayload
+}
+
+// extracts the json webtoken from the request
+//
+// @returns (userID, tokenID, error)
+func extractJWT(c *fiber.Ctx) (int, string, error) {
+	// get the session-cookie
+	cookie := c.Cookies("session")
+
+	token, err := jwt.ParseWithClaims(cookie, &JWT{}, func(token *jwt.Token) (any, error) {
+		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, fmt.Errorf("unexpected JWT signing method: %v", token.Header["alg"])
+		}
+
+		return []byte(config.ClientSession.JwtSignature), nil
+	})
+
+	if err != nil {
+		return -1, "", err
+	}
+
+	// extract the claims from the JWT
+	if claims, ok := token.Claims.(*JWT); ok && token.Valid {
+		return claims.CustomClaims.UserID, claims.CustomClaims.TokenID, nil
+	} else {
+		return -1, "", fmt.Errorf("invalid JWT")
+	}
+}
+
+// user-entry in the database
+type UserDB struct {
+	UserID   int    `json:"userID"`
+	Name     string `json:"name"`
+	Password []byte `json:"password"`
+	Admin    bool   `json:"admin"`
+	TokenID  string `json:"tokenID"`
+}
+
+// checks wether the request is from a valid user
+func checkUser(c *fiber.Ctx) (bool, error) {
+	uid, tid, err := extractJWT(c)
+
+	if err != nil {
+		return false, nil
+	}
+
+	// retrieve the user from the database
+	response, err := db.SelectOld[UserDB]("users", "uid = ? LIMIT 1", uid)
+
+	if err != nil {
+		return false, err
+	}
+
+	// if exactly one user came back and the tID is valid, the user is authorized
+	if len(response) == 1 && response[0].TokenID == tid {
+		// reset the expiration of the cookie
+		setSessionCookie(c, nil)
+
+		return true, err
+	} else {
+		return false, err
+	}
+}
+
+// checks wether the request is from the admin
+func checkAdmin(c *fiber.Ctx) (bool, error) {
+	uid, tokenID, err := extractJWT(c)
+
+	if err != nil {
+		return false, err
+	}
+
+	// retrieve the user from the database
+	response, err := db.SelectOld[UserDB]("users", "uid = ? LIMIT 1", uid)
+
+	if err != nil {
+		return false, err
+	}
+
+	// if exactly one user came back and its name is "admin", the user is the admin
+	if len(response) != 1 {
+		return false, fmt.Errorf("user doesn't exist")
+	} else {
+		return response[0].Name == "admin" && response[0].TokenID == tokenID, err
+	}
+}