Get all of the headers added to a response.
Invoke the iterator callback for each header in the response, using iterator_cls as first argument. Return number of entries iterated over. iterator can be
NULL: in this case the function just counts headers.
iterator should not modify the its key and value arguments, unless we know what we are doing.
Find and return a pointer to the value of a particular header from the response. key must reference a zero-terminated string representing the header to look for. The search is case sensitive. Return
NULLif header does not exist or key is
We should not modify the value, unless we know what we are doing.