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
}

// CreateToken returns a web token as well as a refresh token, which can be used to obtain new tokens.
func CreateToken(userId, jfId string) (string, string, error) {
	var token, refresh string
	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["exp"] = strconv.FormatInt(time.Now().Add(time.Hour*24).Unix(), 10)
	claims["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
}

// Check header for token
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], checkToken)
	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) == "bearer" && expiry.After(time.Now())) {
		app.debug.Printf("Auth denied: Invalid token")
		respond(401, "Unauthorized", gc)
		return
	}
	userID := claims["id"].(string)
	jfID := claims["jfid"].(string)
	match := false
	for _, user := range app.users {
		if user.UserID == userID {
			match = true
			break
		}
	}
	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("Auth succeeded")
	gc.Next()
}

func checkToken(token *jwt.Token) (interface{}, error) {
	if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
		return nil, fmt.Errorf("Unexpected signing method %v", token.Header["alg"])
	}
	return []byte(os.Getenv("JFA_SECRET")), nil
}

type getTokenDTO struct {
	Token string `json:"token" example:"kjsdklsfdkljfsjsdfklsdfkldsfjdfskjsdfjklsdf"` // API token for use with everything else.
}

// getToken checks the header for a username and password, as well as checking the refresh cookie.

// @Summary Grabs an API token using username & password, or via a refresh cookie.
// @description Click the lock icon next to this, login with your normal jfa-go credentials. Click 'try it out', then 'execute' and an API Key will be returned, copy it (not including quotes). On any of the other routes, click the lock icon and use the token as your -Username-. The password can be anything.
// @Produce json
// @Success 200 {object} getTokenDTO
// @Failure 401 {object} stringResponse
// @Router /getToken [get]
// @tags Auth
// @Security getTokenAuth
func (app *appContext) getToken(gc *gin.Context) {
	app.info.Println("Token requested (login attempt)")
	header := strings.SplitN(gc.Request.Header.Get("Authorization"), " ", 2)
	auth, _ := base64.StdEncoding.DecodeString(header[1])
	creds := strings.SplitN(string(auth), ":", 2)
	// check cookie first
	var userID, jfID string
	valid := false
	noLogin := false
	checkLogin := func() {
		if creds[0] == "" || creds[1] == "" {
			app.debug.Println("Auth denied: blank username/password")
			respond(401, "Unauthorized", gc)
			return
		}
		match := false
		for _, user := range app.users {
			if user.Username == creds[0] && user.Password == creds[1] {
				match = true
				app.debug.Println("Found existing user")
				userID = user.UserID
				break
			}
		}
		if !app.jellyfinLogin && !match {
			app.info.Println("Auth denied: Invalid username/password")
			respond(401, "Unauthorized", gc)
			return
		}
		if !match {
			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 denied: Invalid username/password (Jellyfin)")
					respond(401, "Unauthorized", gc)
					return
				}
				app.err.Printf("Auth failed: Couldn't authenticate with Jellyfin (%d/%s)", status, err)
				respond(500, "Jellyfin error", gc)
				return
			}
			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 denied: Users \"%s\" isn't admin", creds[0])
					respond(401, "Unauthorized", gc)
					return
				}
			}
			// New users are only added when using jellyfinLogin.
			userID = shortuuid.New()
			newUser := User{
				UserID: userID,
			}
			app.debug.Printf("Token generated for user \"%s\"", creds[0])
			app.users = append(app.users, newUser)
		}
		valid = true
	}
	checkCookie := func() {
		cookie, err := gc.Cookie("refresh")
		if err == nil && cookie != "" {
			for _, token := range app.invalidTokens {
				if cookie == token {
					if creds[0] == "" || creds[1] == "" {
						app.debug.Println("getToken denied: Invalid refresh token and no username/password provided")
						respond(401, "Unauthorized", gc)
						noLogin = true
						return
					}
					app.debug.Println("getToken: Invalid token but username/password provided")
					return
				}
			}
			token, err := jwt.Parse(cookie, checkToken)
			if err != nil {
				if creds[0] == "" || creds[1] == "" {
					app.debug.Println("getToken denied: Invalid refresh token and no username/password provided")
					respond(401, "Unauthorized", gc)
					noLogin = true
					return
				}
				app.debug.Println("getToken: Invalid token but username/password provided")
				return
			}
			claims, ok := token.Claims.(jwt.MapClaims)
			expiryUnix, err := strconv.ParseInt(claims["exp"].(string), 10, 64)
			if err != nil {
				if creds[0] == "" || creds[1] == "" {
					app.debug.Printf("getToken denied: Invalid token (%s) and no username/password provided", err)
					respond(401, "Unauthorized", gc)
					noLogin = true
					return
				}
				app.debug.Printf("getToken: Invalid token (%s) but username/password provided", err)
				return
			}
			expiry := time.Unix(expiryUnix, 0)
			if !(ok && token.Valid && claims["type"].(string) == "refresh" && expiry.After(time.Now())) {
				if creds[0] == "" || creds[1] == "" {
					app.debug.Printf("getToken denied: Invalid token (%s) and no username/password provided", err)
					respond(401, "Unauthorized", gc)
					noLogin = true
					return
				}
				app.debug.Printf("getToken: Invalid token (%s) but username/password provided", err)
				return
			}
			userID = claims["id"].(string)
			jfID = claims["jfid"].(string)
			valid = true
		}
	}
	checkCookie()
	if !valid && !noLogin {
		checkLogin()
	}
	if valid {
		token, refresh, err := CreateToken(userID, jfID)
		if err != nil {
			app.err.Printf("getToken failed: Couldn't generate token (%s)", err)
			respond(500, "Couldn't generate token", gc)
			return
		}
		gc.SetCookie("refresh", refresh, (3600 * 24), "/", gc.Request.URL.Hostname(), true, true)
		gc.JSON(200, getTokenDTO{token})
	} else {
		gc.AbortWithStatus(401)
	}
}