Not to be argumentative, but what you're trying to do is just so amazingly much more complicated than any of my suggestions. Maybe I haven't communicated it well, it maybe there's some requirement to your project that I don't understand.
Why not just write a listener in PHP and redirect to it? It's basically no work. Handcrafting packets for this purpose is like building a car out of paper clips and cat hair because the car that's freely available to you is red - and you don't like the color red because your old girlfriend used to wear it a lot. miguel On 23 May 2002, Vinod Panicker wrote: > What you said did make sense, and complements my knowledge of > sockets. > > But what i'm not sure of is this - if i construct my own packet > and send it across, presuming that i do have the ip address and > port number of the client on which it is reading, will the client > accept it as a legitimate packet? > > I suspect that since the packets would be having some kind of > session identifier / sequence number. > > Getting the ip address and port number is no problem. I already > have that getting stored on the server. But from what i know of > sockets, i'm sceptical if the client will accept the packet. > > Guess the only way to go ahead is to try this out. > > Would someone pls pls pls write a PHP interface to libnet?? > > Tx, > Vinod. > > On Thu, 23 May 2002 Evan Nemerson wrote : > >You're right- this is getting interesting ;) > > > >http://www.packetfactory.net/libnet/manual/4.html#s4.1.5 > > > >Unless I'm mistaken, you don't need to actually hijack the > >socket- you merely > >need to write to the network. Check out section 3.1 of RFC 793. > >There is > >source and destination port- that is how they are routed. Okay > >anyone PLEASE > >correct me if i'm wrong... > > > >My understanding is a socket is an interface to the kernel. So > >basically, you > >talk to a socket, which the kernel associates with source and > >destination > >ports, and destination IP address. Thats why you can just write > >to a socket > >instead of explicitly stating all the information. The kernel > >then sends out > >then creates the packet and send it to the destination IP. > > > >libnet would allow you to bypass the socket phase, and manually > >create a > >socket. Think of a socket as a GUI for the network, and libnet is > >like a > >console ;) > > > >Hope that helps, and once again anyone PLEASE correct any > >inaccuracies, since > >I want to know. > > > > > > > > > >On Tuesday 21 May 2002 23:53 pm, Vinod Panicker wrote: > > > Thanks for the reply Miguel, but here i'm not trying to > >implement > > > my own multi-threaded server - exactly the reason why i'm > >using > > > Apache / PHP. > > > > > > I could have made a listening server which is based on a > > > multi-threaded or multi-forked model, but the time and > > > complexities involved would be huge. Thats why I chose Apache > >/ > > > PHP. > > > > > > Now if what i'm asking for can be done, developers can > >easily > > > leverage existing efficient server technologies (Apache) to > >build > > > their own App servers. > > > > > > I know that there is no existing function in PHP that would > >allow > > > it to retrieve the socket from Apache ;), all i'm asking for > >is a > > > hack that would allow me to do it. > > > > > > I thought that i'd just as well post it on the mailing list > >before > > > diving into the source code and trying to figure out for > >myself. > > > No point trying to re-invent the wheel, right? > > > > > > Evan, that lib will allow me to create my own packets, but > >which > > > socket do i send it to? Thats been the question all along. > > > > > > I think this is getting really interesting :) > > > > > > Tx, > > > Vinod. > > > > > > On Wed, 22 May 2002 Miguel Cruz wrote : > > > >I don't think you're going to get Apache to hand you the > > > >socket. > > > > > > > >However, you can write a program using the standalone (CGI) > >PHP > > > >interpreter that will act like a server - check out > > > >http://php.net/socket_create_listen for more info. > > > > > > > >You could redirect from your standard web server to your > > > >listening PHP app > > > >running on another port. You'll then have to implement at > >least a > > > >subset > > > >of the HTTP protocol in order to get browsers to talk to > >you. > > > > > > > >Unfortunately, since you can't - to the best of my knowledge > >- > > > >fork a PHP > > > >program, you're going to have to do your own homebrew > >threading > > > >which will > > > >make life slightly complicated. > > > > > > > >miguel > > > > > > > >On 22 May 2002, Vinod Panicker wrote: > > > > > It still seems like I havent made the problem clear > >enough. > > > > > > > > > > I am aware of the print(), echo() and flush() functions > >and > > > > > > > >what > > > > > > > > > they do. It does not fit in as a solution. Let me > >explain > > > > > > > >my > > > > > > > > > problem more elaborately - > > > > > The client calls a PHP script, script_a.php on the > >Apache > > > > > > > >web > > > > > > > > > server, using a Keep-Alive connection. The script > >returns > > > > > > > >some > > > > > > > > > response to the client which it uses. Now since the > > > > > > > >connection is > > > > > > > > > a Keep-alive, apache still has it open for reading and > > > > > > > >writing. > > > > > > > > > When the client wants to call other scripts, it just > >sends > > > > > > > >the > > > > > > > > > request over the same connection. Now the thing is that > >if > > > > > > > >the > > > > > > > > > server needs to send some ASYNCHRONOUS data to the > >client, > > > > > > > >without > > > > > > > > > the client requesting for anything, a normal PHP script > >wont > > > > > > > >be > > > > > > > > > able to do it, since the script would get executed by > >the > > > > > > > >web > > > > > > > > > server ONLY on a client request (coz thats the way HTTP > > > > > > > >works). > > > > > > > > > Now what i was thinking was - if i could get hold of the > > > > > > > >socket > > > > > > > > > that is being used by apache to send data to the client, > >I > > > > > > > >could > > > > > > > > > effectively write() to it, from a C++ app or a PHP > >script > > > > > > > >(which > > > > > > > > > gets invoked from lets say another server). print(), > >echo() > > > > > > > >etc > > > > > > > > > are functions that write to the output stream, which is > >opened > > > > > > > >as > > > > > > > > > a result of the clients request, by the web server. > > > > > > > > > > I want the ability to write to a socket thats been > >created > > > > > > > >earlier > > > > > > > > > - i want to steal it from Apache, so that i can use it > >when > > > > > > > >and > > > > > > > > > where i like. > > > > > > > > > > Functions like echo() and print() are not going to work > >here, > > > > > > > >i > > > > > > > > > will have to use write() so that i can specify the socket > >to > > > > > > > >which > > > > > > > > > the data has to be written! > > > > > > > > > > Hope the problem is understood now. > > > > > > > > > > Now for your question - > > > > > When the client wants to send data to the server, it just > >has > > > > > > > >to > > > > > > > > > open a socket connection with the web server, and issue a > >GET > > > > > > > >or a > > > > > > > > > POST request! if the connection is a keep-alive > >connection, > > > > > > > >and > > > > > > > > > it has already been created, the client just has to do a > >GET > > > > > > > >or a > > > > > > > > > POST without the need to connect(). > > > > > > > > > > This mechanism, where the client frequently connects() > >to > > > > > > > >the > > > > > > > > > server and checks for messages is called polling. One > >way > > > > > > > >of > > > > > > > > > reducing the high overhead of this is to reuse the > >connection > > > > > > > >by > > > > > > > > > using a keep-alive connection. A still better > >improvement > > > > > > > >would > > > > > > > > > be to remove the need for a poll altogether, by doing > > > > > > > >something > > > > > > > > > (thats what my question is all about) on the server so > >that it > > > > > > > >can > > > > > > > > > send data asynchronously to the server. > > > > > > > > > > > > > > > Tx, > > > > > Vinod. > > > > > > > > > > On Wed, 22 May 2002 Bogdan Stancescu wrote : > > > > > >For your specific problem, I think Mr. Lemos has provided > >a > > > > > >viable solution (using print() or echo() and flush() > >whenever > > > > > > > >you > > > > > > > > > >need to, instead of grabbing the socket and write() to > >it). > > > > > > > >My > > > > > > > > > >problem however is how you envision solving the > >communication > > > > > > > >the > > > > > > > > > >other way around (i.e. when the CLIENT wants to send data > >to > > > > > > > >the > > > > > > > > > >server). > > > > > > > > > > > >Bogdan > > > > > > > > > > > >Vinod Panicker wrote: > > > > > >>Hi, > > > > > >> > > > > > >>Tx for your very prompt reply. > > > > > >> > > > > > >>Yeah, I'll post the solution as soon as I find it > > > > > > > >someplace. > > > > > > > > > >>Let me outline the problem in more detail - > > > > > >> > > > > > >>Client (VC++) calls a PHP script on the server, > >specifies > > > > > > > >the > > > > > > > > > >>connection type as Keep-Alive. The PHP script, > >somehow > > > > > > > >(still a > > > > > > > > > >>big question) gets the socket on which the apache > >server > > > > > > > >has > > > > > > > > > >>received the client request (so that it can send data > >to > > > > > > > >the > > > > > > > > > >>client later) and stores it in a database. > > > > > >> > > > > > >>Now whenever another PHP script wants to send data > > > > > >>asynchronously to the client, it gets the socket from > >the > > > > > >>database, and just calls a write() on it. Since the > > > > > > > >connection > > > > > > > > > >>is still open (Keep-Alive), the client receives the > > > > > > > >information, > > > > > > > > > >>and doesnt have to poll the server periodically. > > > > > >> > > > > > >>The application of this is indeed destined for a > >messaging > > > > > >>product, and could benefit a lot of other areas as > >well. > > > > > >> > > > > > >>The only thing that is needed is the socket from > >apache. > > > > > >> > > > > > >>Someone somewhere knows how to get this done, i'm sure > >:) > > > > > >> > > > > > >>Possibly a hack into the PHP module can get this done, > >i'm > > > > > > > >open > > > > > > > > > >>to suggestions. > > > > > >> > > > > > >>Tx, > > > > > >>Vinod. > > > > > >> > > > > > >>On Tue, 21 May 2002 Bogdan Stancescu wrote : > > > > > >>>Hi! > > > > > >>> > > > > > >>>I'm looking for an answer to your questions as well, so > >if > > > > > > > >you > > > > > > > > > >>>do find a solution on other lists, could you please > >post > > > > > > > >it > > > > > > > > > >>>here as well? > > > > > >>> > > > > > >>>Regarding the issue, your proposal wouldn't make for > > > > > >>>full-duplex as far as I understand since I don't see > >how > > > > > > > >the > > > > > > > > > >>>client would be able to send any data on the same > > > > > > > >connection > > > > > > > > > >>>_after_ getting connected. > > > > > >>> > > > > > >>>What are you using on the other end of the pipe (on > >the > > > > > >>>client)? Plain HTML? Flash? Java? Something else? > > > > > >>> > > > > > >>>Bogdan > > > > > >>> > > > > > >>>Vinod Panicker wrote: > > > > > >>>>Hi, > > > > > >>>> > > > > > >>>>We have developed a client-server application where > >the > > > > > > > >server > > > > > > > > > >>>>needs to send asynchronous data to the client. Now > >since > > > > > > > >we > > > > > > > > > >>>>are using Apache/PHP/MySQL, the client needs to poll > >the > > > > > >>>>server periodically for information. > > > > > >>>> > > > > > >>>>I was thinking if there was some way to get around > >this > > > > > > > >basic > > > > > > > > > >>>>problem. I understand that this is how things are > > > > > > > >supposed to > > > > > > > > > >>>>work, but it would be just great if i could PUSH data > > from > > > > > > > >the > > > > > > > > > >>>>server to the client, using HTTP. > > > > > >>>> > > > > > >>>>Since HTTP is a request/response based protocol, > >Apache > > > > > > > >would > > > > > > > > > >>>>not send any data to the client asynchronously. So > >what i > > > > > > > >was > > > > > > > > > >>>>thinking was - If i tell the server to allow > >Keep-Alive > > > > > >>>>connections, and increase the timeout value and max > > > > > > > >requests, > > > > > > > > > >>>>I would effectively have a constant TCP connection. > >Now > > > > > > > >the > > > > > > > > > >>>>only problem would be of sending asynchronous data > >to > > > > > > > >the > > > > > > > > > >>>>client. Solution? Here goes - If there was some way > >in > > > > > > > >which > > > > > > > > > >>>>i could get hold of the file descriptor(socket) that > >is > > > > > > > >being > > > > > > > > > >>>>used by apache to write data to the client, then i > >could, > > > > > > > > from > > > > > > > > > >>>>a PHP script also send any data to the client using > >the > > > > > > > >socket > > > > > > > > > >>>>functions of PHP since i already have the socket > >with > > > > > > > >me. > > > > > > > > > >>>>This would mean that the client doesnt have to poll > >the > > > > > > > >server > > > > > > > > > >>>>for data any more... and if the connection does get > > > > > > > >closed, > > > > > > > > > >>>>the client could reconnect to the server asking for > > > > > > > >another > > > > > > > > > >>>>keep-alive connection. > > > > > >>>> > > > > > >>>>Now I know that this is probably the wrong place to > >put > > > > > > > >such a > > > > > > > > > >>>>query - maybe the apache list would have been > >better. > > > > > > > >But > > > > > > > > > >>>>since I'm using PHP out here, i thought i'd give it > >a > > > > > > > >try. > > > > > > > > > >>>>Does the solution sound very outlandish? Are there > >any > > > > > >>>>pitfalls? And finally, how do i get hold of the > >socket? > > _________________________________________________________ > Click below to visit monsterindia.com and review jobs in India or > Abroad > http://monsterindia.rediff.com/jobs > > > -- PHP Development Mailing List <http://www.php.net/> To unsubscribe, visit: http://www.php.net/unsub.php
