无法检索纯文本，pako.ungzip(message) 抛出异常：标头检查不正确

Question

我有一个服务（用java堆栈编写），它将加密和压缩字符串文本并发送到云服务（在Typescript中）。然后，加密的消息被解压缩和解密，以便在云端进一步处理。

在云中，消息在 Eventhub 上发送并使用 Azure function-eventhub 触发器读取，函数基于 typescript 中的编程模型 V4。

加密（java中）：

 private static byte[] compress(String str) throws IOException {
    ByteArrayOutputStream obj = new ByteArrayOutputStream();
    GZIPOutputStream gzip = new GZIPOutputStream(obj);
    gzip.write(str.getBytes(StandardCharsets.UTF_8));
    gzip.close();
    return obj.toByteArray();
}

在Azure函数eventhub触发器上解密（在打字稿中）：

app.eventHub('EventTrigger', {
  connection: 'connectionString',
  eventHubName: 'eventHubName',
  consumerGroup: 'cg',
  cardinality: 'one',
  extraOutputs: [Output],
  extraInputs: [cosmosInput],
  handler: EventTrigger
});

export async function EventTrigger(message: any, context: InvocationContext): Promise<void> {
  const mh: Handler = new Handler();
  const deviceMessage = mh.decompressBuf(message, context);
  .....
  ....

}

export class Handler {

  decompressBuf(message: string, context?: InvocationContext): MessageObj {
    const decodedMessage=Buffer.from(message);  
    return this.decom(new Uint8Array(decodedMessage) , context);
  }

  decom(message: Uint8Array, context?: InvocationContext): MessageObj {
    let resultGZipArray = pako.ungzip(message);
    var dec:TextDecoderLite = new TextDecoderLite('utf-8');
    const text= dec.decode(resultGZipArray);       
    return JSON.parse(text) as MessageObj;
  }
}

错误如下，

[2024-01-08T08:57:11.082Z] System.Private.CoreLib: Exception while executing function: Functions.EventTrigger. System.Private.CoreLib: Result: Failure
Exception: incorrect header check
Stack: Error: incorrect header check
    at t.ensureErrorType (C:\Program Files\Microsoft\Azure Functions Core Tools\workers\node\dist\src\worker-bundle.js:2:29312)
    at C:\Program Files\Microsoft\Azure Functions Core Tools\workers\node\dist\src\worker-bundle.js:2:45931
    at Generator.throw (<anonymous>)
    at a (C:\Program Files\Microsoft\Azure Functions Core Tools\workers\node\dist\src\worker-bundle.js:2:44362)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5).

任何帮助将不胜感激。

Answer 1

• 确保压缩和解码时使用的编码一致。在 Java 代码中，压缩字符串时使用

  StandardCharsets.UTF_8

  。确保在 TypeScript 中解码时使用相同的编码。

• 向 TypeScript 函数添加更多日志记录，以在尝试解压缩之前显示原始压缩数据和其他相关信息。 解码前的输出：

import { AzureFunction, Context } from  "@azure/functions"

  

const eventHubTrigger: AzureFunction = async  function (context: Context, eventHubMessages: any[]): Promise<void> {

context.log(`Eventhub trigger function called for message array ${eventHubMessages}`);

eventHubMessages.forEach((message, index) => {

context.log(`Processed message ${message}`);

});

};

  

export  default eventHubTrigger;

“解码后输出：”

下面的示例代码适用于事件中心中收到的消息，这些消息采用 Base64 编码，使用 Gzip 压缩，内容预计为 JSON 格式。

import { AzureFunction, Context } from "@azure/functions";
import * as pako from 'pako';

const eventHubTrigger: AzureFunction = async function (context: Context, eventHubMessages: any[]): Promise<void> {
    context.log(`Eventhub trigger function called for message array ${eventHubMessages}`);
    
    eventHubMessages.forEach((message, index) => {
        context.log(`Processing message ${message}`);
        
        const mh: Handler = new Handler();
        const deviceMessage = mh.decompressBuf(message, context);

        // Your further processing logic here with 'deviceMessage'
        if (deviceMessage) {
            context.log(`Device message: ${JSON.stringify(deviceMessage)}`);

            // Continue with your processing logic, e.g., storing in a database, triggering other functions, etc.
        } else {
            context.log.warn('Skipping processing due to empty device message.');
        }
    });
};

class Handler {
    decompressBuf(message: string, context?: Context): any {
        try {
            const decodedMessage = Buffer.from(message, 'base64'); // Assuming the message is base64 encoded
            return this.decompress(new Uint8Array(decodedMessage), context);
        } catch (error) {
            context.log.error(`Error decoding message: ${error}`);
            throw error;
        }
    }

    private decompress(message: Uint8Array, context?: Context): any {
        try {
            if (message.length === 0) {
                context.log.warn('Empty message received. Skipping decompression.');
                return null; // or handle accordingly
            }

            let resultGZipArray = pako.ungzip(message);
            const text = new TextDecoder('utf-8').decode(resultGZipArray);

            return JSON.parse(text);
        } catch (error) {
            context.log.error(`Error during decompression: ${error}`);
            throw error;
        }
    }
}

export default eventHubTrigger;