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Date: Mon, 24 Sep 2012 16:50:10 +0200
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Subject: Re: [PHP-DEV] POST, content-type: application/json and json_decode
From: ivan.enderlin@hoa-project.net ("Ivan Enderlin @ Hoa")

On 24/09/12 16:48, jpauli wrote:
> On Mon, Sep 24, 2012 at 4:21 PM, Ivan Enderlin @ Hoa
> <ivan.enderlin@hoa-project.net> wrote:
>> On 21/09/12 16:16, jpauli wrote:
>>> On Fri, Sep 21, 2012 at 1:05 PM, Ivan Enderlin @ Hoa
>>> <ivan.enderlin@hoa-project.net> wrote:
>>>> Hello,
>>>>
>>>> If PHP receives a HTTP request with the method POST and with the header
>>>> Content-Type: application/x-www-form-encoded, then, it automatically
>>>> parses
>>>> the request body to populate an array in $_POST. If the Content-Type is
>>>> different (e.g. text/plain or application/json), the request body is
>>>> reachable by reading php://input. Well, it is ok.
>>>>
>>>> But is there any plans to consider application/json by parsing the
>>>> request
>>>> body and populate the result in $_POST (with the help of json_decode()
>>>> maybe)?
>>>>
>>>> If so, I would like to propose a patch but I don't find in the source
>>>> code
>>>> where request body is caugth and parsed (for POST). Any ideas?
>>>> Maybe a RFC would also be welcome to complete my suggestion?
>>>>
>>>> Thanks.
>>> Hi !
>>>
>>> Reading and parsing post data function is defined as a SAPI struct
>>> function pointer.
>>> You should look at sapi_module_struct definition
>>> (http://lxr.php.net/xref/PHP_5_4/main/SAPI.h#251).
>>>
>>> When a request comes in, sapi_activate() is called. It then calls
>>> sapi_read_post_data() http://lxr.php.net/xref/PHP_5_4/main/SAPI.c#459
>>> that itself invokes handlers.
>>> Default handlers are defined here :
>>> http://lxr.php.net/xref/PHP_5_4/main/php_content_types.c#29 and for
>>> POST, by default, sapi_read_standard_form_data() is called (defined
>>> here http://lxr.php.net/xref/PHP_5_4/main/SAPI.c#253)
>>> This function is in fact just a bridge, it tells PHP to call
>>> sapi.read_post() which is a function pointer defined by each SAPI.
>>> Finally, later on, sapi.default_post_reader() is called (again, a
>>> function pointer defined by each SAPI)
>> I have some questions. Julien told me in private that he didn't know, hope
>> other could reply.
>>
>> By reading the code, I understand that each SAPI is responsible of parsing
>> the body of a POST request if it is application/x-www-form-urlencoded. Am I
>> right? In SAPI.c, I read that it delegates this task to
>> sapi_module.read_post by giving SG(request_info).post_data (please, see
>> main/SAPI.c#266).
>>
>> It implies that if we would like to add the support of application/json,
>> then we have to do it for each SAPI? Not very nice :-/.
>>
>> When I will locate the code to edit, I'm planning to use php_json_decode_ex
>> & co.  (please, see ext/json/json.c#633), but the hash collision risk is
>> always present. In every case, json_decode() must be protected again hash
>> collision (please, see https://bugs.php.net/60655).
> The hash collision is a behavior our HashTable implementation carries anyway.
> Removing it can only be done safely by changing the hash algorithm,
> which is not such an easy task in case of PHP.
>
> I suggest you start your POC writting the json handler without
> worrying about hash collisions :)
It was my goal, yup.

-- 
Ivan Enderlin
Developer of Hoa
http://hoa.42/ or http://hoa-project.net/

PhD. student at DISC/Femto-ST (Vesontio) and INRIA (Cassis)
http://disc.univ-fcomte.fr/ and http://www.inria.fr/

Member of HTML and WebApps Working Group of W3C
http://w3.org/