On Thu, Apr 2, 2009 at 15:44, Xiaobin <xiaobin...@gmail.com> wrote: > > > > Sorin Manolache wrote: >> >> On Thu, Apr 2, 2009 at 13:28, Xiaobin <xiaobin...@gmail.com> wrote: >>> >>> Hi, everyone. >>> >>> I new to modlue developemnt of the Apache http server, and I have googled >>> this question and can't find the answer. Hope you can help me. Thx. >>> >>> I am confused with the order of the processing of the http request. >>> >>> Without the input/output filters, the order seems quick clear, when one >>> http >>> request comes, it will go through different kinds of hooks like "map to >>> storage", "fixups" and "handler". And we can set some handlers to deal >>> with >>> these hooks. >>> >>> But what's the order after the introduction of the filter mechanism？ >>> >>> When will the input filters begin to work? >>> After the handlers of the fixups hook has been called and before the >>> handlers of the "handler" hook begin to work? >>> Or in some other order? >>> And how can we specify the order of the input filters? >>> >>> And for the output filters, when did they begin to work? Before or after >>> the >>> "log transaction" hook ? >>> And also how can we specify the order of the output filters? >>> >>> Thank you very much for your help! >> >> There are several types of filters: network, protocol, connection, >> resource (the list is not exhaustive, check util_filters.h in the >> apache sources). >> >> The input headers of the request are read after the create_request >> hook and before the post_read_request, quick_handler, translate_name, >> map_to_storage, header_parser, access_checker, ..., fixups, >> insert_filter, and handler hooks. >> >> The output headers of the request are written during the handler >> execution. >> >> When the headers are read/written, the protocol filters are called. >> >> The resource input/output filters are called only when you explicitly >> read/write the body of the request. If you add filters with the >> SetInputFilter/SetOutputFilter directives, the filter is added in the >> insert_filter hook. This one is called after fixups and before >> handler. Thus, you cannot use a filter added with >> SetInputFilter/SetOutputFilter before the handler hook. >> >> log_transaction is called after the request was served and the >> response was written to the socket and the socket flushed. >> >> If the filters are of the same type, they are run in the order they >> were added. If they are of different types, then I think their type >> takes precedence, but I am not sure of that. For output filters, >> resource filters are called before network filters. >> >> S >> -- >> A: Because it reverses the logical flow of conversation. >> Q: Why is top-posting frowned upon? >> A: Top-posting. >> Q: What is the most annoying thing in e-mail? >> >> > > > Thank you very much! > > So, the resouce/content input filter will be called after fixups hook and > before > handler hook, is this right?
No. They are run _after_ the fixup hook. They are invoked _from_ (not before) the handler hook. In the handler you call ap_get_brigade and it is this call that invokes the input filters. Remember that the filters are not automatically invoked. You need to call ap_get_brigade to call the input filters and ap_pass_brigade to call the output filters. So simply adding a filter in translate_name will not read anything. If, for example, you don't care about the body of the POST request and you don't call ap_get_brigade from the handler, the input filters are not called, even if they are present. > If this is right, is it possible to make the input filter run earlier? Like > after the translate_name hook and before the map_to_storage hook? Yes, it is possible. You hook the translate_name or the map_to_storage hook. In your callback you call ap_add_input_filter, you do what you want, and then you remove the filters. If you do not remove them, insert_filter in ap_invoke_handler (which is called after fixups) will add them a second time and then chances are that you won't get what you want. > And I am not so understand about this part: > "Thus, you cannot use a filter added with SetInputFilter/SetOutputFilter > before the handler hook." > > Do you mean that in the httpd.conf file, the SetHandler instruction should > be set before the SetInputFilter/SetOutputFilter instructions ? No. It means that code that is run before the handler hook works in the _absence_ of the filters. The filters are added just before the handler hook. Only the handler hook will benefit of the presence of the filters. S -- A: Because it reverses the logical flow of conversation. Q: Why is top-posting frowned upon? A: Top-posting. Q: What is the most annoying thing in e-mail?
