kotlin - Ktor 客户端身份验证功能不发送授权 header

Question

我试图在 Kotlin/MPP(多平台)项目和 JVM 目标功能中使用 ktor client 似乎没有效果。

下面是一个重现的例子:

import io.ktor.client.HttpClient
import io.ktor.client.features.ResponseException
import io.ktor.client.features.auth.Auth
import io.ktor.client.features.auth.providers.basic
import io.ktor.client.features.json.JsonFeature
import io.ktor.client.features.json.serializer.KotlinxSerializer
import io.ktor.client.features.logging.DEFAULT
import io.ktor.client.features.logging.LogLevel
import io.ktor.client.features.logging.Logger
import io.ktor.client.features.logging.Logging
import io.ktor.client.request.get
import io.ktor.client.request.header
import kotlinx.coroutines.runBlocking
import java.util.*

fun main() = runBlocking {
    val client = HttpClient {
        install(Logging) {
            logger = Logger.DEFAULT
            level = LogLevel.HEADERS
        }
        install(JsonFeature) {
            serializer = KotlinxSerializer()
        }
        install(Auth) {
            basic {
                username = "user"
                password = "pass"
            }
        }
    }
    val url = "https://en.wikipedia.org/wiki/Main_Page"

    val failing = try {
        client.get<String>(url)
    } catch (e: ResponseException) {
        "failed"
    }

    val succeeding = try {
        client.get<String>(url) {
            header("Authorization", "Basic ${Base64.getEncoder().encodeToString("user:pass".toByteArray())}")
        }
    } catch (e: ResponseException) {
        "failed"
    }
}

观察

从记录器输出中，您可以看到客户端不发送 Authorization header ，但是当我手动提供此类 header 时，我没有遇到任何问题:

第一个请求(失败的例子:)

[main] INFO io.ktor.client.HttpClient - REQUEST: https://en.wikipedia.org/wiki/Main_Page
[main] INFO io.ktor.client.HttpClient - METHOD: HttpMethod(value=GET)
[main] INFO io.ktor.client.HttpClient - COMMON HEADERS
[main] INFO io.ktor.client.HttpClient - -> Accept: application/json
[main] INFO io.ktor.client.HttpClient - -> Accept-Charset: UTF-8
[main] INFO io.ktor.client.HttpClient - CONTENT HEADERS

第二个请求(后续示例:)

[main] INFO io.ktor.client.HttpClient - REQUEST: https://en.wikipedia.org/wiki/Main_Page
[main] INFO io.ktor.client.HttpClient - METHOD: HttpMethod(value=GET)
[main] INFO io.ktor.client.HttpClient - COMMON HEADERS
[main] INFO io.ktor.client.HttpClient - -> Authorization: Basic dXNlcjpwYXNz
[main] INFO io.ktor.client.HttpClient - -> Accept: application/json
[main] INFO io.ktor.client.HttpClient - -> Accept-Charset: UTF-8
[main] INFO io.ktor.client.HttpClient - CONTENT HEADERS

环境

Kotlin:1.4-M1

Ktor Artifacts 1.3.1 版:

ktor-client-core

ktor-client-logging

ktor-client-json

ktor 客户端序列化

ktor-client-auth-basic

我错过了什么？

Answer 1

请添加 sendWithoutRequest = true

https://api.ktor.io/1.3.1/io.ktor.client.features.auth.providers/-basic-auth-config/send-without-request.html

 install(Auth) {
            basic {
                sendWithoutRequest = true
                username = "user"
                password = "pass"
            }
        }

结果:

sending with sendWithoutRequest set to true
[main] INFO io.ktor.client.HttpClient - REQUEST: https://en.wikipedia.org/wiki/Main_Page
[main] INFO io.ktor.client.HttpClient - METHOD: HttpMethod(value=GET)
[main] INFO io.ktor.client.HttpClient - COMMON HEADERS
[main] INFO io.ktor.client.HttpClient - -> Authorization: Basic dXNlcjpwYXNz
[main] INFO io.ktor.client.HttpClient - -> Accept: application/json
[main] INFO io.ktor.client.HttpClient - -> Accept-Charset: UTF-8
[main] INFO io.ktor.client.HttpClient - CONTENT HEADERS

解释:

By default, Ktor will wait for the server to respond with 401, Unauthorized, and only then send the authentication header. In your example, wiki never responds with a 401, as it is not a protected resource. Therefore, adding sendWithoutRequest is required. If you tried with some url that does respond with a 401, you would see that Ktor will then send a second request (after receiving 401) with the authentication header. You can try with this url to see - https://api.sumologic.com/api/v1/collectors.

这是在关闭 sendWithoutRequest 的情况下针对该 protected api 完成的日志记录，即您的原始输入。如您所见，现在有 2 个请求，第一个没有授权 header ，第二个有授权 header ，在服务器响应 401 之后。

sending with sendWithoutRequest set to false and hitting a protected resource
    [main] INFO io.ktor.client.HttpClient - REQUEST: https://api.sumologic.com/api/v1/collectors
    [main] INFO io.ktor.client.HttpClient - METHOD: HttpMethod(value=GET)
    [main] INFO io.ktor.client.HttpClient - COMMON HEADERS
    [main] INFO io.ktor.client.HttpClient - -> Accept: application/json
    [main] INFO io.ktor.client.HttpClient - -> Accept-Charset: UTF-8
    [main] INFO io.ktor.client.HttpClient - CONTENT HEADERS
    [main] INFO io.ktor.client.HttpClient - REQUEST: https://api.sumologic.com/api/v1/collectors
    [main] INFO io.ktor.client.HttpClient - METHOD: HttpMethod(value=GET)
    [main] INFO io.ktor.client.HttpClient - COMMON HEADERS
    [main] INFO io.ktor.client.HttpClient - -> Accept: application/json
    [main] INFO io.ktor.client.HttpClient - -> Accept-Charset: UTF-8
    [main] INFO io.ktor.client.HttpClient - -> Authorization: Basic dXNlcjpwYXNz
    [main] INFO io.ktor.client.HttpClient - CONTENT HEADERS

注意:我刚刚看到 Andylamax 的评论说新版本“修复”了它。也许，我不知道，因为我还没有尝试过那个新版本。但我想补充一点，这不是 Ktor 独有的东西，至少在这方面不是错误(但也许他们改变了主意？再说一次，我不知道)。事实上，正是我使用 C# 的经验让我怀疑这里发生了什么并找到答案。 C# 中的 WebRequest 的行为方式相同，您需要将 PreAuthenticate 设置为 true 以立即发送凭据。见这里 https://docs.microsoft.com/en-us/dotnet/api/system.net.webrequest.preauthenticate?view=netcore-3.1 。