Expose the status of requests

[jpatel531]

Hi there,

Whenever I got 401 errors, the library would panic. The GCM response for 401s are in HTML, whereas the library was trying to parse the body from JSON regardless of the status.

This PR adds a Status field to the HttpResponse struct, and also returns an error upon a non-200 response.

Let me know what you think

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[jpatel531]

I've also signed the license agreement

[googlebot]

CLAs look good, thanks!

[bolshoy]

@jpatel531 You are ditching the response body, which can contain useful info. A better way on my opinion is to always read the body, try to unmarshal it, and if failed return the body as is.

[jpatel531]

Fair point @bolshoy - although from reading the reference ( https://developers.google.com/cloud-messaging/http-server-ref#error-codes ) it doesn't look like non-200 bodies contain anything particularly interesting. How would you suggest we return a raw body? Include a RawBody []byte in the HttpResponse struct?

[bolshoy]

@jpatel531 I don't think the upstream client is really interested in the response status code and its meaning, it needs either a response object or an error explaining why there's no object. So in case of http statuses 400,401,5xx in the spec, it would be something along the lines of

gcmResp := &HttpResponse{}
body, err := ioutil.ReadAll(httpResp.Body)
defer httpResp.Body.Close()
if err != nil {
        return nil, fmt.Errorf("error reading http response body: %v", err)
}
if httpResp.StatusCode >= http.StatusBadRequest { // Not sure about 3xx 
        return nil, fmt.Errorf(fmt.Sprintf("http error: %s (%s)", httpResp.Status, string(body)))
}
err = json.Unmarshal(body, &gcmResp)
if err != nil {
        return nil, fmt.Errorf("error unmarshaling json from body: %v %s", err, string(body))
}