【Azure 服务总线】使用Azure Service Bus 时，出现证书错误: 所使用的证书具有无法验证的信任链

问题描述

在Azure中连接 Service Bus 服务发送消息时发生证书错误，抛出证书异常消息：

或

The X.509 certificate CN=servicebus.chinacloudapi.cn, OU=Azure, O=Shanghai Blue Cloud Technology Co Ltd, L=Shanghai, S=Shanghai, C=CN is not in the trusted people store. 
The X.509 certificate CN=servicebus.chinacloudapi.cn, OU=Azure, O=Shanghai Blue Cloud Technology Co Ltd, L=Shanghai, S=Shanghai, C=CN chain building failed. 
The certificate that was used has a trust chain that cannot be verified. 
Replace the certificate or change the certificateValidationMode. 
A certificate chain could not be built to a trusted root authority.

问题解答

如果在连接Service Bus的代码中不对 ConnectivityMode 做预先设置，Service Bus SDK默认使用了 AutoDetect 模式 连接 Service Bus 服务。 

AutoDetect 会优先使用 TCP 连接模式，由于 TCP 连接模式也是加密的，所以客户端需要首先验证 service bus 服务器证书 CN = servicebus.chinacloudapi.cn 的有效性，证书链信息在 SSL 协议的 server hello 消息中返回。

如果证书链中的某些中间证书没有安装在 web 应用实例上，web 应用需要发起额外的请求到 CA 服务器上下载中间证书并安装。当下面任何一种情况发生时，web 应用无法对 service bus 服务器证书建立信任的证书链，随后会报告上述的证书错误：

1. 运行Service Bus客户端代码的实例和 CA 服务器之间存在网络问题，导致无法下载证书.
2. 运行Service Bus客户端代码的实例无法成功安装证书，如权限问题等。

推荐在代码中强制使用 HTTPS 模式连接 Service Bus 服务，HTTPS 模式有不同的设计，因此会很大程度上避免上述错误发生。

示例代码如下：

string connectionString = "servicebus connection string";

ServiceBusEnvironment.SystemConnectivity.Mode = ConnectivityMode.Https

var namespaceManager = NamespaceManager.CreateFromConnectionString(connectionString);

if (!namespaceManager.TopicExists("TestTopic"))
{
    namespaceManager.CreateTopic("TestTopic");
}

TopicClient client = TopicClient.CreateFromConnectionString(connectionString, "TestTopic");

BrokeredMessage testMessage = new BrokeredMessage("test message");
testMessage.MessageId = "message id";

client.Send(testMessage);

另外，以上代码代码使用很旧的Service Bus SDK，强烈建议升级SDK代码，使用新的AMQP协议连接Service Bus

using Azure.Messaging.ServiceBus;

// the client that owns the connection and can be used to create senders and receivers
ServiceBusClient client;
// The Service Bus client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when messages are being published or read
// regularly.
//
// set the transport type to AmqpWebSockets so that the ServiceBusClient uses the port 443. 
// If you use the default AmqpTcp, you will need to make sure that the ports 5671 and 5672 are open

// TODO: Replace the <NAMESPACE-CONNECTION-STRING> and <QUEUE-NAME> placeholders
var clientOptions = new ServiceBusClientOptions()
{ 
    TransportType = ServiceBusTransportType.AmqpWebSockets
};
client = new ServiceBusClient("<NAMESPACE-CONNECTION-STRING>", clientOptions);

参考文档

添加将消息发送到队列的代码  : ​​https://learn.microsoft.com/zh-cn/azure/service-bus-messaging/service-bus-dotnet-get-started-with-queues?tabs=passwordless#add-code-to-send-messages-to-the-queue​​ 

当在复杂的环境中面临问题，格物之道需：浊而静之徐清，安以动之徐生。 云中，恰是如此!