Capturing HTTP traffic using Fiddler from Java applicaiton

Question

I'm having difficulty using Fiddler to diagnose a problem in a Java application to connect to Microsoft Graph's API. Here's my basic environment:

JDK: 1.8.0_131 Apache HttpClient: 4.4 Fiddler: 4.6

The endpoint I'm trying to reach is https://login.microsoftonline.com/common/oauth2/authorize The problem I have is that the traffic is not captured by Fiddler.

I've tried various things as suggested by Googling for this problem, but have not got it to work. In my application, I set the proxy settings as follows:

httpClientBuilder.setProxy(new HttpHost(proxyServer, proxyPort, proxyScheme));
httpClientBuilder.build();

• If I use ("127.0.0.1", 8888, "https"): then the error that I see is: Unrecognized SSL message, plaintext connection?
• If I use ("127.0.0.1", 8888, "http"): then the error that I see is: I/O exception (org.apache.http.conn.UnsupportedSchemeException) caught when processing request to {tls}->http://127.0.0.1:8888->https://login.microsoftonline.com:443: http protocol is not supported

I've tried other things (for example "localhost", "localhost.", and so on as suggested, and setting: -Djsse.enableSNIExtension=false), but so far no luck. Hopefully I am missing something obvious! Thanks for any help.

Answer 1

It turns out that the second configuration for the proxy is the correct one to use (using "http"), but what I had forgotten was that I was setting a ConnectionSocketFactoryRegistry in my HttpClientBuilder. I had not registered a ConnectionSocketFactory for "http" and this caused the second configuration to fail. I added this to the HttpClientBuilder, and now I can see traffic being captured by Fiddler:

connectionSocketFactoryRegistryBuilder.register("http", new PlainConnectionSocketFactory());