Re: Apache modification questions
Hi, A post doesn't normally have anything in the > QUERY_STRING. Rather a POSTed form has the stuff > being sent in the request body, which is read from > STDIN by a script. QUERY_STRING is still available > for use. Consider this form: > > form method=post action=myscript.cgi > input name=emailaddress > > The "emailaddress" input would NOT appear > in QUERY_STRING, but rather would appear to > the script as STDIN, or to another module as > the request body. You can still do: > > form method=post action=myscript.cgi?id=reallyunique > input name=emailaddress U yeah you are right, I am not thinking. Cheers, Andrej
Re: Apache modification questions
> This is a bit awkward since the QUERY_STRING in POST > can be anything, for example an XML-documents. .. > Though, how should I deal with, for example, an > XML-document in a POST requests? Where should I > "hide" the transaction identifier? A post doesn't normally have anything in the QUERY_STRING. Rather a POSTed form has the stuff being sent in the request body, which is read from STDIN by a script. QUERY_STRING is still available for use. Consider this form: form method=post action=myscript.cgi input name=emailaddress The "emailaddress" input would NOT appear in QUERY_STRING, but rather would appear to the script as STDIN, or to another module as the request body. You can still do: form method=post action=myscript.cgi?id=reallyunique input name=emailaddress -- Ray Morris
Re: Apache modification questions
Hi, > > 1) What is the "recommended" way to carry the > > GET/POST request identifier (inserted by the > > developer of the web page) from the client > > to Apache? > >You're not going to get the browser to send > a custom header by any changes you make to the > page, except possibly using Ajax. Javascript isn't > enabled on all browsers, so that's out for a > public web site. Cookies also are often turned > off, so that's out, if it's a public site. > That leaves the QUERY_STRING, mainly. (What > you're calling GET variables). We have another > way that's better for many sites, but there are > patent issues with that method. (My company > is seeking a patent.) Now I am curious, but I bet you are not going to tell me! > Using the query string > means rewriting the content of each page, so > one could do what PHP does and use cookies if > they are available, then failover to query string > if cookies are not sent by the browser. > > This is a bit awkward since the QUERY_STRING in POST can be anything, for example an XML-documents. I wonder why it is impossible to add a HTTP Request Header in Javascript. Does anybody know? With AJAX and ActionScript (or Flex 3) it can be done with a few lines of code. Anyway, I guess I could write an Apache module with a hook-method that attemps to get the identifier from 1) Custom HTTP request header 2) A Cookie 3) QUERY_STRING In this order and DECLINE if not found. Though, how should I deal with, for example, an XML-document in a POST requests? Where should I "hide" the transaction identifier? Best regards, Andrej
Re: Apache modification questions
As another poster said, a standard CGI script runs in a different processes and you can't generally muck with the address space of that process. To effect that script, what you can do is change it's inputs and it's outputs. Your module can add, remove, or alter the query string, path info, translate the URL, etc. Then you can also filter the output from the script to change it before it's sent to to the browser. I get an odd feeling here about something. I get the feeling that you may get better results by going back to a higher level view of your problem. You're thinking about how to attach to the CGI process but you don't yet have enough information to know if that would be a good way to achieve your goal, for example. As a matter of fact an Apache module may well not be what you need. I suggest that you go back and look at the actual business goal you're trying to achieve and perhaps email me about it off list as I may be able to help you find the right general approach and then point you in the right direction. -- Ray B. Morris [EMAIL PROTECTED]
Re: Apache modification questions
On Fri, 2008-09-05 at 18:49 +0900, Andrej van der Zee wrote: > Hi, > > > > > A CGI script is run by the code of a module, mod_perl, mod_php5, etc. > > In their register_hooks function they register their handler, which is > > a script interpreter basically. The handler callback is invoked in the > > same thread that did the rest of the request processing (URL parsing, > > authentication, fixups, etc). I think there seems to be a confusion about terminology here: a CGI-script by definition runs in its own process, _not_ within the process address space of the webserver (hence the need for a defined "Common Gateway Interface" to pass request information to the external application. See http://en.wikipedia.org/wiki/Common_Gateway_Interface). Now, since the forking/spanwing is a rather time consuming operation there are embedded interpreters for most of the commons scripting languages (like perl/python etc.). Those often have a compatibility layer to run unmodified CGI code within the webservers address/process space (with sometimes strage side efects :-/). > However, I don't know if the handler > > callback (of mod_perl, mod_php5, etc), which can be seen as a sort of > > third-party black box, spawns new processes/threads in which they > > parse the script, compile, etc. I guess they do not spawn new > > threads/processes but you have to read their docs or their sources in > > order to be sure. If they do not spawn new threads/processes, then the > > CGI is executed in the same thread as fixups and the rest of the > > request processing. > > > > Thanks that makes sense. > > If understood correctly, this means that I can add my own module to > the chain of request processors that executes in the same thread as > the hook function in mod_php5/mod_perl that executes CGI scripts. For the embedded interpreters that's true. > Though, if the module's hook function spawns a new process/thread for > handling the CGI script is dependent on the module. CGIs are handled by mod_cgi. > Does anybody know if the hook functions of such modules usually > spawning a new thread/process? My guess is that at least for compiled > CGI application written in C/C++ a new process is forked in the hook > function. Iff those are real CGIs (applications) that's true. HTH Ralf Mattes > Cheers, > Andrej > >
Re: Apache modification questions
Andrej van der Zee wrote: > Does anybody know if the hook functions of such modules usually > spawning a new thread/process? My guess is that at least for compiled > CGI application written in C/C++ a new process is forked in the hook > function. > This is just off the top of my head, so I have no solid proof for this, and please correct me if I'm wrong. I would think that the reason for having an Apache module for PHP/Perl would be to avoid the overhead of initialising the interpreter for every page - it initialises itself once at Apache start, and then resets its state for each request. Or so I would hope. Using a module also gives them access to some Apache internals that CGI applications can't reach. CGI applications (including mod_suphp and PHP/Perl run as CGI scripts) would be forked. Dave
Re: Apache modification questions
Hi, > > A CGI script is run by the code of a module, mod_perl, mod_php5, etc. > In their register_hooks function they register their handler, which is > a script interpreter basically. The handler callback is invoked in the > same thread that did the rest of the request processing (URL parsing, > authentication, fixups, etc). However, I don't know if the handler > callback (of mod_perl, mod_php5, etc), which can be seen as a sort of > third-party black box, spawns new processes/threads in which they > parse the script, compile, etc. I guess they do not spawn new > threads/processes but you have to read their docs or their sources in > order to be sure. If they do not spawn new threads/processes, then the > CGI is executed in the same thread as fixups and the rest of the > request processing. > Thanks that makes sense. If understood correctly, this means that I can add my own module to the chain of request processors that executes in the same thread as the hook function in mod_php5/mod_perl that executes CGI scripts. Though, if the module's hook function spawns a new process/thread for handling the CGI script is dependent on the module. Does anybody know if the hook functions of such modules usually spawning a new thread/process? My guess is that at least for compiled CGI application written in C/C++ a new process is forked in the hook function. Cheers, Andrej -- Andrej van der Zee 2-40-19 Koenji-minami Suginami-ku, Tokyo 166-0003 JAPAN Mobile: 0031-(0)80-65251092 Phone/Fax: 0031-(0)3-3318-3155
Re: Apache modification questions
On Fri, Sep 5, 2008 at 11:19, Andrej van der Zee <[EMAIL PROTECTED]> wrote: > Hi, > > Thanks for your comments. > >> >> child_init is not the appropriate hook for your purpose. Use >> ap_hook_fixups for getting the ID and ap_hook_log_transaction for >> logging. > > In ap_hook_fixups, is it possible to get the thread/process ID of the > CGI application serving the request? Moreover, is this thread/process > already created? Or maybe the hook function is executed in the same > thread/process as the CGI application? A CGI script is run by the code of a module, mod_perl, mod_php5, etc. In their register_hooks function they register their handler, which is a script interpreter basically. The handler callback is invoked in the same thread that did the rest of the request processing (URL parsing, authentication, fixups, etc). However, I don't know if the handler callback (of mod_perl, mod_php5, etc), which can be seen as a sort of third-party black box, spawns new processes/threads in which they parse the script, compile, etc. I guess they do not spawn new threads/processes but you have to read their docs or their sources in order to be sure. If they do not spawn new threads/processes, then the CGI is executed in the same thread as fixups and the rest of the request processing. S
Re: Apache modification questions
Hi, Thanks for your comments. > > child_init is not the appropriate hook for your purpose. Use > ap_hook_fixups for getting the ID and ap_hook_log_transaction for > logging. In ap_hook_fixups, is it possible to get the thread/process ID of the CGI application serving the request? Moreover, is this thread/process already created? Or maybe the hook function is executed in the same thread/process as the CGI application? > > Every module has a "register_hooks" function. There, you call the two > ap_hook functions above in order to hook your callbacks to the fixups > and log_transaction events. Next you implement the two callbacks and > that's it. > That's clear. Cheers, Andrej -- Andrej van der Zee 2-40-19 Koenji-minami Suginami-ku, Tokyo 166-0003 JAPAN Mobile: 0031-(0)80-65251092 Phone/Fax: 0031-(0)3-3318-3155
Re: Apache modification questions
Thanks for your comments. Until I get the book, can you tell if a module's hook function can execute in the same thread as the CGI application that serves the request? Also, I am unable to find the apache2 API for building modules. I found some documentation for developers on the apache2 website, but the link for "Autogenerated Apache 2 code documentation" is not working. Thank you, Andrej -- Andrej van der Zee 2-40-19 Koenji-minami Suginami-ku, Tokyo 166-0003 JAPAN Mobile: 0031-(0)80-65251092 Phone/Fax: 0031-(0)3-3318-3155
Re: Apache modification questions
On Fri, Sep 5, 2008 at 05:11, Andrej van der Zee <[EMAIL PROTECTED]> wrote: > 2) I do need to "attach" to the thread/process handling the request to > extract information just after starting and just before ending. Can I > do this in an Apache module? I found the ap_hook_child_init() function > but no similar exit()-function. Moreover, I need to access the request > identifier and log to a file. Can all this be done in an Apache > module? child_init is not the appropriate hook for your purpose. Use ap_hook_fixups for getting the ID and ap_hook_log_transaction for logging. Every module has a "register_hooks" function. There, you call the two ap_hook functions above in order to hook your callbacks to the fixups and log_transaction events. Next you implement the two callbacks and that's it. S
Re: Apache modification questions
> Can all this be done in an Apache module? Yes, just about anything can be done in an Apache module. Based on your other questions, it sounds like you need a thorough exposition of the Apache API and probably the HTTP protocol, so I'd suggets your next step is to study some good documentation, such as the Apache Modules book. > 1) What is the "recommended" way to carry the > GET/POST request identifier (inserted by the > developer of the web page) from the client > to Apache? You're not going to get the browser to send a custom header by any changes you make to the page, except possibly using Ajax. Javascript isn't enabled on all browsers, so that's out for a public web site. Cookies also are often turned off, so that's out, if it's a public site. That leaves the QUERY_STRING, mainly. (What you're calling GET variables). We have another way that's better for many sites, but there are patent issues with that method. (My company is seeking a patent.) Using the query string means rewriting the content of each page, so one could do what PHP does and use cookies if they are available, then failover to query string if cookies are not sent by the browser. -- Ray B. Morris [EMAIL PROTECTED] Strongbox - The next generation in site security: http://www.bettercgi.com/strongbox/ Throttlebox - Intelligent Bandwidth Control http://www.bettercgi.com/throttlebox/ Strongbox / Throttlebox affiliate program: http://www.bettercgi.com/affiliates/user/register.php On 09/04/2008 10:11:39 PM, Andrej van der Zee wrote: > Hi, > > I am about to modify Apache with some custom logging for GET/POST > requests (and more). It is for the purpose of research. If possible, > I > would like to get some guidance in how to implement my ideas. I will > explain... > > Every GET/POST request to Apache will carry a request identifier. > Adding the identifier to the request is the responsibility of the > developer of the web page. In Apache (NOT the CGI application) I > would like to extract the identifier from the request and write it to > a log together with timestamp, request serve time and some specific > information about the thread/process that handles the request. The > CGI > application serving the request should be untouched! I have two > issues > I would like to get some comments about, if possible: > > 1) What is the "recommended" way to carry the GET/POST request > identifier (inserted by the developer of the web page) from the > client > to Apache? Add a custom HTTP header? Or should I do it in GET/POST > variables? Any other alternatives? > 2) I do need to "attach" to the thread/process handling the request > to > extract information just after starting and just before ending. Can I > do this in an Apache module? I found the ap_hook_child_init() > function > but no similar exit()-function. Moreover, I need to access the > request > identifier and log to a file. Can all this be done in an Apache > module? > > Hope you can help! > > Cheers, > Andrej > > -- > Andrej van der Zee > 2-40-19 Koenji-minami > Suginami-ku, Tokyo > 166-0003 JAPAN > Mobile: 0031-(0)80-65251092 > Phone/Fax: 0031-(0)3-3318-3155 >
Apache modification questions
Hi, I am about to modify Apache with some custom logging for GET/POST requests (and more). It is for the purpose of research. If possible, I would like to get some guidance in how to implement my ideas. I will explain... Every GET/POST request to Apache will carry a request identifier. Adding the identifier to the request is the responsibility of the developer of the web page. In Apache (NOT the CGI application) I would like to extract the identifier from the request and write it to a log together with timestamp, request serve time and some specific information about the thread/process that handles the request. The CGI application serving the request should be untouched! I have two issues I would like to get some comments about, if possible: 1) What is the "recommended" way to carry the GET/POST request identifier (inserted by the developer of the web page) from the client to Apache? Add a custom HTTP header? Or should I do it in GET/POST variables? Any other alternatives? 2) I do need to "attach" to the thread/process handling the request to extract information just after starting and just before ending. Can I do this in an Apache module? I found the ap_hook_child_init() function but no similar exit()-function. Moreover, I need to access the request identifier and log to a file. Can all this be done in an Apache module? Hope you can help! Cheers, Andrej -- Andrej van der Zee 2-40-19 Koenji-minami Suginami-ku, Tokyo 166-0003 JAPAN Mobile: 0031-(0)80-65251092 Phone/Fax: 0031-(0)3-3318-3155
