backend/auth/auth.go

package auth

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"time"

	"acooldomain.co/backend/models"
	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"golang.org/x/crypto/bcrypt"
)

var secret []byte
var method string

type Connection struct {
	connection *mongo.Client
}

type TokenInfo struct {
	Username    string            `json:"username"`
	Permissions models.Permission `json:"permissions"`
}

type AuthClaims struct {
	*jwt.StandardClaims
	TokenInfo
}

type InviteToken struct {
	Email       string              `bson:"Email"`
	Permissions []models.Permission `bson:"Permissions"`
	Token       string              `bson:"Token"`
}

func signToken(token TokenInfo) (string, error) {

	t := jwt.New(jwt.GetSigningMethod(method))

	t.Claims = &AuthClaims{
		&jwt.StandardClaims{
			ExpiresAt: time.Now().Add(time.Hour * 24 * 30).Unix(),
		},
		token,
	}

	return t.SignedString(secret)
}

func hashPassword(password string) (string, error) {
	bytes, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	return string(bytes), err
}

func AuthorizedTo(requiredPermissions models.Permission, overwriters ...func(*gin.Context) bool) gin.HandlerFunc {
	return func(ctx *gin.Context) {
		authCookie, err := ctx.Request.Cookie("auth")
		if err != nil {
			ctx.AbortWithError(403, err)
			return
		}

		token, err := jwt.ParseWithClaims(authCookie.Value, &AuthClaims{}, func(token *jwt.Token) (interface{}, error) {
			// Don't forget to validate the alg is what you expect:
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
			}

			// hmacSampleSecret is a []byte containing your secret, e.g. []byte("my_secret_key")
			return secret, nil
		})
		if err != nil {
			ctx.AbortWithError(403, err)
			return
		}
		if claims, ok := token.Claims.(*AuthClaims); ok && token.Valid {
			ctx.Set("claims", claims)
			if requiredPermissions&claims.Permissions != requiredPermissions && models.Admin&claims.Permissions != models.Admin {
				for _, overwrite := range overwriters {
					if overwrite(ctx) {
						return
					}
				}
				ctx.AbortWithStatus(403)
				return
			}
		} else {
			ctx.AbortWithStatus(500)
		}
	}
}

type SignUpRequest struct {
	Token    string
	Username string
	Password string
}

func (con Connection) signUp(c *gin.Context) {
	var token TokenInfo

	err := json.NewDecoder(c.Request.Body).Decode(&token)
	if err != nil {
		c.AbortWithError(500, err)
	}

	signedToken, err := signToken(token)
	if err != nil {
		c.AbortWithError(500, err)
	}

	c.SetCookie("auth", signedToken, -1, "", "", false, false)
	c.IndentedJSON(http.StatusOK, signedToken)
}

type SignInRequest struct {
	Username string `json:"username"`
	Password string `json:"password"`
}

func (con Connection) signIn(c *gin.Context) {

	var request SignInRequest
	err := json.NewDecoder(c.Request.Body).Decode(&request)

	if err != nil {
		c.AbortWithError(500, err)
		return
	}
	var userItem models.User
	err = con.connection.Database("Backend").Collection("Users").FindOne(context.TODO(), bson.D{{Key: "Username", Value: request.Username}}).Decode(&userItem)
	if err != nil {
		c.AbortWithError(403, err)
		return
	}

	if bcrypt.CompareHashAndPassword([]byte(userItem.HashedPass), []byte(request.Password)) != nil {
		c.AbortWithStatus(403)
		return
	}

	token := TokenInfo{
		Username:    userItem.Username,
		Permissions: userItem.Permissions,
	}

	signedToken, err := signToken(token)
	if err != nil {
		c.AbortWithError(500, err)
		return
	}

	c.SetCookie("auth", signedToken, -1, "", "", false, false)
	c.IndentedJSON(http.StatusOK, signedToken)
}

func (con Connection) test(c *gin.Context) {
	claims, exists := c.Get("claims")
	if !exists {
		fmt.Println("No Claims")
		c.AbortWithStatus(403)
		return
	}
	c.IndentedJSON(http.StatusOK, claims)
}

func LoadGroup(group *gin.RouterGroup, client *mongo.Client, config models.GlobalConfig) {
	connection := Connection{connection: client}

	secret = []byte(config.Key)
	method = config.Algorithm

	group.POST("/signin", connection.signIn)
	group.POST("/signup", AuthorizedTo(models.Admin), connection.signUp)
	group.GET("/test", AuthorizedTo(models.Admin), connection.test)
}