jfa-go/auth.go

package main

import (
	"encoding/base64"
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/dgrijalva/jwt-go"
	"github.com/gin-gonic/gin"
	"github.com/lithammer/shortuuid/v3"
)

func (app *appContext) webAuth() gin.HandlerFunc {
	return app.authenticate
}

func (app *appContext) authenticate(gc *gin.Context) {
	header := strings.SplitN(gc.Request.Header.Get("Authorization"), " ", 2)
	if header[0] != "Basic" {
		app.debug.Println("Invalid authentication header")
		respond(401, "Unauthorized", gc)
		return
	}
	auth, _ := base64.StdEncoding.DecodeString(header[1])
	creds := strings.SplitN(string(auth), ":", 2)
	token, err := jwt.Parse(creds[0], func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			app.debug.Printf("Invalid JWT signing method %s", token.Header["alg"])
			return nil, fmt.Errorf("Unexpected signing method %v", token.Header["alg"])
		}
		return []byte(os.Getenv("JFA_SECRET")), nil
	})
	if err != nil {
		app.debug.Printf("Auth denied: %s", err)
		respond(401, "Unauthorized", gc)
		return
	}
	claims, ok := token.Claims.(jwt.MapClaims)
	var userId string
	var jfId string
	expiryUnix, err := strconv.ParseInt(claims["exp"].(string), 10, 64)
	if err != nil {
		app.debug.Printf("Auth denied: %s", err)
		respond(401, "Unauthorized", gc)
		return
	}
	expiry := time.Unix(expiryUnix, 0)
	if ok && token.Valid && claims["type"].(string) == "bearer" && expiry.After(time.Now()) {
		userId = claims["id"].(string)
		jfId = claims["jfid"].(string)
	} else {
		app.debug.Printf("Invalid token")
		respond(401, "Unauthorized", gc)
		return
	}
	match := false
	for _, user := range app.users {
		if user.UserID == userId {
			match = true
		}
	}
	if !match {
		app.debug.Printf("Couldn't find user ID %s", userId)
		respond(401, "Unauthorized", gc)
		return
	}
	gc.Set("jfId", jfId)
	gc.Set("userId", userId)
	app.debug.Println("Authentication successful")
	gc.Next()
}

func (app *appContext) GetToken(gc *gin.Context) {
	app.info.Println("Token requested (login attempt)")
	header := strings.SplitN(gc.Request.Header.Get("Authorization"), " ", 2)
	if header[0] != "Basic" {
		app.debug.Println("Invalid authentication header")
		respond(401, "Unauthorized", gc)
		return
	}
	auth, _ := base64.StdEncoding.DecodeString(header[1])
	creds := strings.SplitN(string(auth), ":", 2)
	match := false
	var userId, jfId string
	for _, user := range app.users {
		if user.Username == creds[0] && user.Password == creds[1] {
			if creds[0] != "" && creds[1] != "" {
				match = true
				app.debug.Println("Found existing user")
				userId = user.UserID
			}
		}
	}
	if !match {
		if !app.jellyfinLogin {
			app.info.Println("Auth failed: Invalid username and/or password")
			respond(401, "Unauthorized", gc)
			return
		}
		cookie, err := gc.Cookie("refresh")
		if err == nil && cookie != "" && creds[0] == "" && creds[1] == "" {
			fmt.Println("Checking:", cookie)
			for _, token := range app.invalidTokens {
				if cookie == token {
					app.debug.Printf("Auth denied: Refresh token in blocklist")
					respond(401, "Unauthorized", gc)
					return
				}
			}
			token, err := jwt.Parse(cookie, func(token *jwt.Token) (interface{}, error) {
				if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
					app.debug.Printf("Invalid JWT signing method %s", token.Header["alg"])
					return nil, fmt.Errorf("Unexpected signing method %v", token.Header["alg"])
				}
				return []byte(os.Getenv("JFA_SECRET")), nil
			})
			if err != nil {
				app.debug.Printf("Auth denied: %s", err)
				respond(401, "Unauthorized", gc)
				return
			}
			claims, ok := token.Claims.(jwt.MapClaims)
			expiryUnix, err := strconv.ParseInt(claims["exp"].(string), 10, 64)
			if err != nil {
				app.debug.Printf("Auth denied: %s", err)
				respond(401, "Unauthorized", gc)
				return
			}
			expiry := time.Unix(expiryUnix, 0)
			if ok && token.Valid && claims["type"].(string) == "refresh" && expiry.After(time.Now()) {
				userId = claims["id"].(string)
				jfId = claims["jfid"].(string)
			} else {
				app.debug.Printf("Invalid token (invalid or not refresh type)")
				respond(401, "Unauthorized", gc)
				return
			}
		} else {
			var status int
			var err error
			var user map[string]interface{}
			user, status, err = app.authJf.authenticate(creds[0], creds[1])
			if status != 200 || err != nil {
				if status == 401 || status == 400 {
					app.info.Println("Auth failed: Invalid username and/or password")
					respond(401, "Invalid username/password", gc)
					return
				}
				app.err.Printf("Auth failed: Couldn't authenticate with Jellyfin: Code %d", status)
				respond(500, "Jellyfin error", gc)
				return
			} else {
				jfId = user["Id"].(string)
				if app.config.Section("ui").Key("admin_only").MustBool(true) {
					if !user["Policy"].(map[string]interface{})["IsAdministrator"].(bool) {
						app.debug.Printf("Auth failed: User \"%s\" isn't admin", creds[0])
						respond(401, "Unauthorized", gc)
					}
				}
				newuser := User{}
				newuser.UserID = shortuuid.New()
				userId = newuser.UserID
				// uuid, nothing else identifiable!
				app.debug.Printf("Token generated for user \"%s\"", creds[0])
				app.users = append(app.users, newuser)
			}
		}
	}
	token, refresh, err := CreateToken(userId, jfId)
	if err != nil {
		respond(500, "Error generating token", gc)
	}
	resp := map[string]string{"token": token}
	gc.SetCookie("refresh", refresh, (3600 * 24), "/", gc.Request.URL.Hostname(), true, true)
	gc.JSON(200, resp)
}

func CreateToken(userId string, jfId string) (string, string, error) {
	var token, refresh string
	var err error
	claims := jwt.MapClaims{
		"valid": true,
		"id":    userId,
		"exp":   strconv.FormatInt(time.Now().Add(time.Minute*20).Unix(), 10),
		"jfid":  jfId,
		"type":  "bearer",
	}

	tk := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	token, err = tk.SignedString([]byte(os.Getenv("JFA_SECRET")))
	if err != nil {
		return "", "", err
	}

	claims = jwt.MapClaims{
		"valid": true,
		"id":    userId,
		"exp":   strconv.FormatInt(time.Now().Add(time.Hour*24).Unix(), 10),
		"jfid":  jfId,
		"type":  "refresh",
	}

	tk = jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	refresh, err = tk.SignedString([]byte(os.Getenv("JFA_SECRET")))
	if err != nil {
		return "", "", err
	}

	return token, refresh, nil
}

func respond(code int, message string, gc *gin.Context) {
	resp := map[string]string{"error": message}
	gc.JSON(code, resp)
	gc.Abort()
}