Ktor 客户端身份验证功能不发送授权标头

Question

我试图在 Kotlin/MPP（多平台）项目和 JVM 目标功能中使用ktor 客户端，基本身份验证似乎没有效果。

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标头，但是当我手动提供此类标头时，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

• 科特林：1.4-M1

Ktor Artifacts 1.3.1 版：

• ktor-客户端-核心
• ktor-client-logging
• ktor-client-json
• ktor-client-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：

默认情况下，Ktor 将等待服务器响应 401（未经授权），然后才发送身份验证标头。在您的示例中，wiki 永远不会响应 401，因为它不是受保护的资源。因此，需要添加sendWithoutRequest。如果您尝试使用某些确实以 401 响应的 url，您会看到 Ktor 将发送带有身份验证标头的第二个请求（在收到 401 后）。您可以尝试使用此网址查看 - https://api.sumologic.com/api/v1/collectors。

这是在关闭 sendWithoutRequest 的情况下针对受保护的 api 完成的日志记录，即您的原始输入。正如您所看到的，现在发出了 2 个请求，第一个请求没有授权标头，第二个请求在服务器响应 401 后带有授权标头。

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，这并不是 Ktor 独有的东西，至少在这方面不是一个错误（但也许他们改变了主意？同样，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了答案。C# 中的 WebRequest 的行为方式相同，您需要将 PreAuthenticate 设置为 true 才能立即发送凭据。请参阅此处https://docs.microsoft.com/en-us/dotnet/api/system.net.webrequest.preauthenticate?view=netcore-3.1。