Wireshark中C#/Python/CURL调用Azure API的HTTP可见性不一致问题

我使用Azure TTS API生成文字对应的音频，C#代码原本运行正常，但发现部分词汇会返回空音频。尝试用Python和CURL调用同一API，却能正常获取这些词汇的音频。

为排查请求差异，我配置Wireshark通过SSLKEYLOGFILE解密TLS流量，结果运行Python代码时能看到完整HTTP请求，但运行C#和CURL时仅能看到TCP和TLS流量，无法查看HTTP请求内容，想了解不同语言/工具抓包结果存在差异的原因。

C# 代码片段 #

string subscriptionKey = Environment.GetEnvironmentVariable("STT_API_KEY");
Authentication auth = new Authentication("https://eastus.api.cognitive.microsoft.com/sts/v1.0/issueToken", subscriptionKey);
try
{
    accessToken = await auth.FetchTokenAsync().ConfigureAwait(false);
    //Console.WriteLine("Successfully obtained an access token. \n");
}
catch (Exception ex)
{
    //Console.WriteLine("Failed to obtain an access token.");
    //Console.WriteLine(ex.ToString());
    //Console.WriteLine(ex.Message);
    return null;
}

string host = "https://eastus.tts.speech.microsoft.com/cognitiveservices/v1";

// Create SSML document.
XDocument body = new XDocument(
        new XElement("speak",
            new XAttribute("version", "1.0"),
            new XAttribute(XNamespace.Xml + "lang", "en-US"),
            new XElement("voice",
                new XAttribute(XNamespace.Xml + "lang", "en-US"),
                new XAttribute(XNamespace.Xml + "gender", "Female"),
                new XAttribute("name", "en-US-AvaNeural"), // Short name for "Microsoft Server Speech Text to Speech Voice (en-US, Jessa24KRUS)"
                text)));

using (HttpClient client = new HttpClient())
{
    using (HttpRequestMessage request = new HttpRequestMessage())
    {
        // Set the HTTP method
        request.Method = HttpMethod.Post;
        // Construct the URI
        request.RequestUri = new Uri(host);
        // Set the content type header
        request.Content = new StringContent(body.ToString(), Encoding.UTF8, "application/ssml+xml");
        // Set additional header, such as Authorization and User-Agent
        request.Headers.Add("Authorization", "Bearer " + accessToken);
        request.Headers.Add("Connection", "Keep-Alive");
        // Update your resource name
        request.Headers.Add("User-Agent", "YOUR_RESOURCE_NAME");
        // Audio output format. See API reference for full list.
        request.Headers.Add("X-Microsoft-OutputFormat", "riff-24khz-16bit-mono-pcm");
        // Create a request
        //Console.WriteLine("Calling the TTS service. Please wait... \n");
        using (HttpResponseMessage response = await client.SendAsync(request).ConfigureAwait(false))
}

Python 代码片段 #

endpoint = 'https://eastus.tts.speech.microsoft.com/cognitiveservices/v1'
ssml = """
<speak version='1.0' xml:lang='en-US'>
  <voice xml:lang='en-US' xml:gender='Female' name='en-US-AvaNeural'>
    black
  </voice>
</speak>
"""

headers = {
    'Ocp-Apim-Subscription-Key': subscription_key,
    'Content-Type': 'application/ssml+xml',
    'X-Microsoft-OutputFormat': 'audio-16khz-32kbitrate-mono-mp3'
}

response = requests.post(endpoint, headers=headers, data=ssml, verify=False)

内容的提问来源于stack exchange，提问作者tzviya