Retriving data from http request,

How do I get the raw data from a http request? i.e. in a post request, the content that will be submitted is followed after the request header and the request header contains the CONTENT-LENGTH specifying the length of the data. I know PHP will parse the submitted content so that each "key=value" pair will become variable name $key holding value. Now my question is, is there a way in PHP that I can just get those "non-parse" content from the request only? I have found the documentation it seems that there is no obivous to do so, get the env. variable "QUERY_STRING" seems match my needs but it only work for GET/string appended in the URL only. I need to do so since I need to handle the such post request that don't use "key=value" pair. Thanks a lot