Add more debugging info to server logs for failed OAuth requests (#7039)

app/oauth.go

@@ -672,23 +672,26 @@ func AuthorizeOAuthUser(w http.ResponseWriter, r *http.Request, service, code, s
 	req.Header.Set("Accept", "application/json")
 
 	var ar *model.AccessResponse
-	var respBody []byte
+	var bodyBytes []byte
 	if resp, err := utils.HttpClient().Do(req); err != nil {
 		return nil, "", nil, model.NewLocAppError("AuthorizeOAuthUser", "api.user.authorize_oauth_user.token_failed.app_error", nil, err.Error())
 	} else {
+		bodyBytes, _ = ioutil.ReadAll(resp.Body)
+		resp.Body = ioutil.NopCloser(bytes.NewBuffer(bodyBytes))
+
 		ar = model.AccessResponseFromJson(resp.Body)
 		defer CloseBody(resp)
 		if ar == nil {
-			return nil, "", nil, model.NewLocAppError("AuthorizeOAuthUser", "api.user.authorize_oauth_user.bad_response.app_error", nil, "")
+			return nil, "", nil, model.NewLocAppError("AuthorizeOAuthUser", "api.user.authorize_oauth_user.bad_response.app_error", nil, "response_body="+string(bodyBytes))
 		}
 	}
 
 	if strings.ToLower(ar.TokenType) != model.ACCESS_TOKEN_TYPE {
-		return nil, "", nil, model.NewLocAppError("AuthorizeOAuthUser", "api.user.authorize_oauth_user.bad_token.app_error", nil, "token_type="+ar.TokenType+", response_body="+string(respBody))
+		return nil, "", nil, model.NewLocAppError("AuthorizeOAuthUser", "api.user.authorize_oauth_user.bad_token.app_error", nil, "token_type="+ar.TokenType+", response_body="+string(bodyBytes))
 	}
 
 	if len(ar.AccessToken) == 0 {
-		return nil, "", nil, model.NewLocAppError("AuthorizeOAuthUser", "api.user.authorize_oauth_user.missing.app_error", nil, "")
+		return nil, "", nil, model.NewLocAppError("AuthorizeOAuthUser", "api.user.authorize_oauth_user.missing.app_error", nil, "response_body="+string(bodyBytes))
 	}
 
 	p = url.Values{}