contrib: 🐛 [Bug]: i18n middleware panics

Bug Description

While running multiple requests in parallel fiber panics due to i18n translations. Of course it can be handled with recover package but this is not ideal in my case.

panic: runtime error: slice bounds out of range [:-1]

goroutine 63 [running]:
github.com/valyala/fasthttp.releaseArg(...)
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/args.go:469
github.com/valyala/fasthttp.(*Args).ParseBytes(0x1400028a200, {0x0?, 0x140004218b8?, 0x104cf4fc8?})
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/args.go:102 +0x30c
github.com/valyala/fasthttp.(*URI).parseQueryArgs(...)
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/uri.go:895
github.com/valyala/fasthttp.(*URI).QueryArgs(...)
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/uri.go:887
github.com/valyala/fasthttp.(*RequestCtx).QueryArgs(0x1400028a000)
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/server.go:989 +0x4c
github.com/gofiber/fiber/v2.(*Ctx).Query(0x1400044e000, {0x104d29384, 0x4}, {0x0, 0x0, 0x0?})
        /Users/kacper/go/pkg/mod/github.com/gofiber/fiber/v2@v2.48.0/ctx.go:1050 +0x38
github.com/gofiber/contrib/fiberi18n.defaultLangHandler(0x860086?, {0x104d48450, 0x2})
        /Users/kacper/go/pkg/mod/github.com/gofiber/contrib/fiberi18n@v1.0.0/config.go:82 +0x40
github.com/gofiber/contrib/fiberi18n.GetMessage({0x104e186a0?, 0x104e98b50})
        /Users/kacper/go/pkg/mod/github.com/gofiber/contrib/fiberi18n@v1.0.0/i18n.go:101 +0x78
github.com/gofiber/contrib/fiberi18n.MustGetMessage(...)
        /Users/kacper/go/pkg/mod/github.com/gofiber/contrib/fiberi18n@v1.0.0/i18n.go:83
main.main.func1(0x1400044e000)
        /Users/kacper/GolandProjects/i18nbugfix/main.go:20 +0x30
github.com/gofiber/fiber/v2.(*App).next(0x14000080d80, 0x1400044e000)
        /Users/kacper/go/pkg/mod/github.com/gofiber/fiber/v2@v2.48.0/router.go:144 +0x184
github.com/gofiber/fiber/v2.(*Ctx).Next(0x14000028488?)
        /Users/kacper/go/pkg/mod/github.com/gofiber/fiber/v2@v2.48.0/ctx.go:909 +0x5c
github.com/gofiber/contrib/fiberi18n.New.func1(0x104e343c0?)
        /Users/kacper/go/pkg/mod/github.com/gofiber/contrib/fiberi18n@v1.0.0/i18n.go:31 +0x78
github.com/gofiber/fiber/v2.(*App).next(0x14000080d80, 0x1400044e000)
        /Users/kacper/go/pkg/mod/github.com/gofiber/fiber/v2@v2.48.0/router.go:144 +0x184
github.com/gofiber/fiber/v2.(*App).handler(0x14000080d80, 0x104c69dc0?)
        /Users/kacper/go/pkg/mod/github.com/gofiber/fiber/v2@v2.48.0/router.go:171 +0x74
github.com/valyala/fasthttp.(*Server).serveConn(0x140001c6000, {0x104e9e838?, 0x1400048e180})
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/server.go:2363 +0xdd0
github.com/valyala/fasthttp.(*workerPool).workerFunc(0x140000d2fa0, 0x14000068360)
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/workerpool.go:224 +0x70
github.com/valyala/fasthttp.(*workerPool).getCh.func1()
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/workerpool.go:196 +0x38
created by github.com/valyala/fasthttp.(*workerPool).getCh
        /Users/kacper/go/pkg/mod/github.com/valyala/fasthttp@v1.48.0/workerpool.go:195 +0x220

How to Reproduce

Steps to reproduce the behavior:

Run server
Run command ab -n 10000 -c 50 http://127.0.0.1:3000/ few times (just wait for each of it to finish)

Expected Behavior

Program should work and return translated response without panicking

Contrib package Version

v1.0.0

Code Snippet (optional)

package main

import (
	"github.com/gofiber/contrib/fiberi18n"
	"github.com/gofiber/fiber/v2"
	"golang.org/x/text/language"
)

func main() {
  app := fiber.New()
	app.Use(
		fiberi18n.New(&fiberi18n.Config{
			RootPath:         "./localize",
			AcceptLanguages:  []language.Tag{language.English, language.Polish},
			FormatBundleFile: "json",
			DefaultLanguage:  language.English,
		}),
	)
	app.Get("/", func(c *fiber.Ctx) error {
		return c.SendString(fiberi18n.MustGetMessage("hello"))
	})

	app.Listen("127.0.0.1:3000")
}

Checklist:

I agree to follow Fiber’s Code of Conduct.
I have checked for existing issues that describe my problem prior to opening this one.
I understand that improperly formatted bug reports may be closed without explanation.

About this issue

Original URL
State: closed
Created 10 months ago
Comments: 17 (14 by maintainers)

Most upvoted comments

@gaby @efectn which one looks best for you?

I vote for option 2, although we should rename the functions, they are too verbose.

From:

c.SendString(fiberi18n.MustGetMessage(c, "welcome"))

To:

c.SendString(fiberi18n.Get(c, "welcome"))

gaby on Aug 27, 2023

Or just wait for a new version of middleware to be released?

we are currently working on a fix, this will unfortunately take a few days to ensure that this problem is completely solved this time after that we will publish a new version and you will switch to this one

ReneWerner87 on Aug 29, 2023

@ReneWerner87 @KompocikDot

I’ve decided to give up appCfg.ctx = ctx

Use ctx.Local to store configuration information, which not only binds to the ctx, but also avoids using appCfg globally and reduces the risk of panic.

// New creates a new middleware handler
func New(config ...*Config) fiber.Handler {
	appCfg := configDefault(config...)
	// init bundle
	bundle := i18n.NewBundle(appCfg.DefaultLanguage)
	bundle.RegisterUnmarshalFunc(appCfg.FormatBundleFile, appCfg.UnmarshalFunc)
	appCfg.bundle = bundle

	appCfg.loadMessages().initLocalizerMap()

	return func(c *fiber.Ctx) error {
		if appCfg.Next != nil && appCfg.Next(c) {
			return c.Next()
		}
               // appCfg.Ctx = c
		c.Locals("fiberi18n", appCfg)
		return c.Next()
	}
}

func GetMessage(ctx *fiber.Ctx, params interface{}) (string, error) {
        // lang := appCfg.LangHandler(appCfg.ctx, appCfg.DefaultLanguage.String()
	appCfg := ctx.Locals("fiberi18n").(*Config)
	lang := appCfg.LangHandler(ctx, appCfg.DefaultLanguage.String())
        // ...
}

And I found out that the main cause of the panic is the defaultLangHandler. Where *fiber.Ctx is most possibly nil.

So I think there needs to be a break change to the api, which is clearly a problem with the design I started with

func defaultLangHandler(c *fiber.Ctx, defaultLang string) string {
	if c == nil || c.Request() == nil {
		return defaultLang
	}
	var lang string
	lang = utils.CopyString(c.Query("lang"))
	if lang != "" {
		return lang
	}
	lang = utils.CopyString(c.Get("Accept-Language"))
	if lang != "" {
		return lang
	}

	return defaultLang
}

Skyenought on Aug 26, 2023