c# - 切换到 IPV6 时 HttpClient 抛出异常 - 被 iOS 商店拒绝

Question

我正在处理的 Xamarin 项目遇到一个奇怪的问题，我很困惑......

我使用 HTTPClient 发出异步请求。但是，我的应用程序因未能满足 Apple 的 IPV6 要求而被应用程序商店拒绝。也就是说，当通过 IPV6 连接时，我使用 HTTPClient 发出的请求失败。奇怪的是，只有当应用程序在 IPV4 网络上启动然后切换到 IPV6 网络时，它才会失败。如果我在连接到 IPV6 网络时重新启动应用程序，它会成功!另外，如果我启动连接到 IPV6 的应用程序然后切换到 IPV4 网络，它也会成功。只有在 IPV4 中启动然后切换到 IPV6 时才会失败。

这非常奇怪 - 就像 HttpClient 正在缓存一些东西，但我们为每个请求创建一个新的客户端。我没有使用 IP 地址 - 只是一个地址，正如我所提到的，当应用程序启动连接到仅 IPV6 网络时它可以工作。似乎只是从 IPV4 切换到 IPV6 导致了这个问题。

PCL中存在的代码:

var client = new HttpClient();
var urlToCall = new Uri("https://www.something.com/someapi/v1");
// Add some headers
...
response = client.GetAsync(urlToCall);

和堆栈跟踪:

Trace.Message": "Error: ConnectFailure (Network is unreachable)
at System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult) [0x00065] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/System/System.Net/HttpWebRequest.cs:946 
at System.Threading.Tasks.TaskFactory`1[TResult].FromAsyncCoreLogic (IAsyncResult iar, System.Func`2 endFunction, System.Action`1 endAction, System.Threading.Tasks.Task`1 promise, Boolean requiresSynchronization) <0x10019c730 + 0x0005b> in <filename unknown>:0 
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x0003b] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:199 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[TResult].GetResult () <0x10013ccc0 + 0x0001b> in <filename unknown>:0 
at System.Net.Http.HttpClientHandler+<SendAsync>c__async0.MoveNext () [0x003d6] in /Library/Frameworks/Xamarin.iOS.framework/Versions/9.6.1.9/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClientHandler.cs:372 
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x0003b] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:199 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[TResult].GetResult () <0x10013ccc0 + 0x0001b> in <filename unknown>:0 
at System.Net.Http.HttpClient+<SendAsyncWorker>c__async0.MoveNext () [0x000a9] in /Library/Frameworks/Xamarin.iOS.framework/Versions/9.6.1.9/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClient.cs:274 
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x0003b] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:199 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:170 
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:142 
at System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () <0x10013c8c0 + 0x0001b> in <filename unknown>:0 
at MyApp.RestClient.RestService`2+<SendHttpRequest>d__10[TInput,TOutput].MoveNext () [0x00259] in <filename unknown>:0 
Network is unreachable
at System.Net.Sockets.Socket.Connect (System.Net.EndPoint remoteEP) [0x000bc] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/System/System.Net.Sockets/Socket.cs:1235 
at System.Net.WebConnection.Connect (System.Net.HttpWebRequest request) [0x001c2] in /Users/builder/data/lanes/3051/5f11db87/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/System/System.Net/WebConnection.cs:213 

有没有人见过这样的事情？有没有人知道如何修复甚至调试这个问题？

Answer 1

在 iOS build设置中，将 HttpClient Implementation 设置为使用 NSURLSession。

Link to Xamarin Documentation

The default continues to be an HttpClient that is powered by HttpWebRequest, while you can now optionally switch to an implementation that uses iOS’s, tvOS's or OS X's native transports (NSUrlSession or CFNetwork depending on the OS). The upside is smaller binaries, and faster downloads, the downside is that it requires the event loop to be running for async operations to be executed.

您使用的是主机名，而不是硬编码的 IPv4 IP 地址，这是个好消息!如果您使用硬编码的 IPv4 IP 地址，Apple 将拒绝您的应用。

确保检查您的主机名是否可以解析 IPv6 IP 地址。 System.Net.Dns 中还有一些有用的方法可以帮助您解析 IP 地址，以查看 IPv6 是否可用。

您也可以尝试使用 .MapToIPv6() 扩展方法:Link to MSDN documentation .