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hey, I created a jwttoken, and the token is expired, so when GET the backend url, the server throws ...
# ktor
k
hey, I created a jwttoken, and the token is expired, so when GET the backend url, the server throws an error
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com.auth0.jwt.exceptions.TokenExpiredException: The Token has expired on 2024-01-16T08:48:32Z.
I want to know how can I return a json response instead of throwing an error
t
hi, StatusPages allows you to map specific exceptions to specific responses
k
ok, I got it
hey, it seems not working, here is the stacktrace
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2024-01-16 19:22:57.999 [DefaultDispatcher-worker-5] TRACE io.ktor.server.auth.Authentication - Trying to authenticate / with auth-jwt
2024-01-16 19:22:58.050 [DefaultDispatcher-worker-5] TRACE io.ktor.auth.jwt - Token verification failed
com.auth0.jwt.exceptions.TokenExpiredException: The Token has expired on 2024-01-16T08:48:32Z.
	at com.auth0.jwt.JWTVerifier$BaseVerification.assertValidInstantClaim(JWTVerifier.java:346)
	at com.auth0.jwt.JWTVerifier$BaseVerification.lambda$addMandatoryClaimChecks$17(JWTVerifier.java:308)
and this is the code
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install(StatusPages) {
        exception(TokenExpiredException::class) { call, _ ->
            call.respond(Response.Err("token expired"))
        }
    }
where is the error of my code ?
t
you can also have a look at the minimal status pages example from the documentation: https://github.com/ktorio/ktor-documentation/tree/2.3.7/codeSnippets/snippets/status-pages
k
eh, does statuspage just catch the error from routing ?
t
thats the main usecase yes, “when GET the backend url” sounds a lot like routing 😅 your authentication setup is also something that is happening inside the routing, right?
k
nope, I am still looking for where the error throws, please hang on
eh, the error is from
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authenticate("auth-jwt") {
            get("/") {
                val principal = call.principal<UserIdPrincipal>()
                if (principal == null) {
                    call.respond(HttpStatusCode.Unauthorized, Response.Err("not login"))
                } else {
                    val username = principal.name
                    call.respond(Response.Ok("get ok", "you are $username"))
                }
            }
        }
but I can't catch the error by StatusPages
t
can you change the exception you are catching to throwable (exceptionThrowable)? just to be sure you are looking at the correct exception… this should catch everything
k
really ? actually I have written this code
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install(StatusPages) {
        exception<Throwable> { call, cause ->
            call.respond(Response.Err("Fuck"))
        }

        status(HttpStatusCode.NotFound) { call, status ->
            call.respondText(text = "404: Page Not Found", status = status)
        }

        exception<TokenExpiredException> { call, cause ->
            call.respond(HttpStatusCode.Unauthorized, Response.Err(cause.message ?: "Fuck"))
        }
    }
but still not work
if you don't mind, talk is cheap, can you check the code, it is very simple, don't worry 😋
jwtdemo.zip
t
do you have multiple modules? your authentication plugin seems to work, but it seems like your StatusPages plugin is not applied at all 🤔
k
yes, but actually the StatusPages works well on this code
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fun Application.configureException() {
    install(StatusPages) {
        exception<Throwable> { call, cause ->
            call.respond(Response.Err("Fuck"))
        }

        status(HttpStatusCode.NotFound) { call, status ->
            call.respondText(text = "404: Page Not Found", status = status)
        }

        exception<TokenExpiredException> { call, cause ->
            call.respond(HttpStatusCode.Unauthorized, Response.Err(cause.message ?: "Fuck"))
        }
    }

    routing {
        get("/error/") {
            call.respondText("Hello, world!")
        }
        get("/error/internal-error") {
            throw Exception("Internal Server Error")
        }
        get("/error/authorization-error") {
            throw Exception("Forbidden Error")
        }
        get("/error/authentication-error") {
            call.respond(HttpStatusCode.Unauthorized)
        }
        get("/error/payment-error") {
            call.respond(HttpStatusCode.PaymentRequired)
        }
    }
}
t
i am busy right now, i might check your zip later 🤞
k
thank you, I will be waitting for your response 🙂
t
your StatusPages work perfectly fine (e.g. seen when using a path that is not routed) seems like the authentication part is not throwing an exception, the easiest fix would be to configure StatusPages for the Unauthorized Http Code
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status(HttpStatusCode.Unauthorized) { call, status ->
    call.respondText(text = "401: Unauthorized!", status = status)
}
If you need more control i think using challenge in the authentication and throwing the exceptions yourself would be an option, as seen here
k
thanks, I choose using challenge
by the way, can I think the challenge as the interceptor of validate ?
I think the TokenExpiredException is not thrown, but printed and catched, right ? so I can't catch this error
t
hm i see it more as a different behaviour than the default in case the authentication fails
k
may be I should make a issue of ktor, anyway thanks for your help
t
k
ok
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