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NullPointerException in Http1ExchangeCodec.readResponseHeaders() in OkHttp 3.14.0

See original GitHub issue

Since upgrading OkHttp from 3.13.1 to 3.14.0 in our Android app, some of our users experience crashes because of a NullPointerException in Http1ExchangeCodec line 233.

Relevant stacktrace:

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'okhttp3.Route okhttp3.internal.connection.RealConnection.route()' on a null object reference
       at okhttp3.internal.http1.Http1ExchangeCodec.readResponseHeaders(Http1ExchangeCodec.java:233)
       at okhttp3.internal.connection.RealConnection.createTunnel(RealConnection.java:400)
       at okhttp3.internal.connection.RealConnection.connectTunnel(RealConnection.java:236)
       at okhttp3.internal.connection.RealConnection.connect(RealConnection.java:177)
       at okhttp3.internal.connection.ExchangeFinder.findConnection(ExchangeFinder.java:224)
       at okhttp3.internal.connection.ExchangeFinder.findHealthyConnection(ExchangeFinder.java:107)
       at okhttp3.internal.connection.ExchangeFinder.find(ExchangeFinder.java:87)
       at okhttp3.internal.connection.Transmitter.newExchange(Transmitter.java:162)
       at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:41)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)
...

The majority of the crashes occur on Motorola devices. We have not been able to reproduce the issue on a test device, but it seems related to the app forcing a request over WiFi, and users having a proxy set on the device.

The cause of the NullPointerException is easy to find from the stacktrace, though. From RealConnection:

      Http1ExchangeCodec tunnelCodec = new Http1ExchangeCodec(null, null, source, sink);
      source.timeout().timeout(readTimeout, MILLISECONDS);
      sink.timeout().timeout(writeTimeout, MILLISECONDS);
      tunnelCodec.writeRequest(tunnelRequest.headers(), requestLine);
      tunnelCodec.finishRequest();
      Response response = tunnelCodec.readResponseHeaders(false)
          .request(tunnelRequest)
          .build();

The second argument to Http1ExchangeCodec() (realConnection) is passed as null, which causes readResponseHeaders() to throw a NullPointerException when an EOFException is encountered.