1. Socket Program For Echo Ping Talk Commands In C 5
2. Socket Program For Echo Ping Talk Commands In Computer
3. Socket Program For Echo Ping Talk Commands In C 3

EJP286 2-Apr-13 18:292-Apr-13 18:29'Although the listen function is the easiest way to listen on a port and act as the server, it is not the most desirable.' This is complete nonsense. Listen is the only way to 'listen on a port and act as a server'.You will quickly find out when you attempt it that your program will freeze until an incoming connection is made.No, you won't find that out. Your program will not freeze at that point.because listen is a 'blocking' function – it can only perform one task at a time, and will not return until a connection is pending.No it isn't. Listen is not a blocking function, and it returns immediately.This is definitely a problemNo it isn't.You can then specify, with the next and final parameter, how many remote computers can communicate with your server at the same timeNo you can't. That's not what the parameter is for.

It suggests a value for the size of the backlog queue.we just pass SOMAXCONN (SOcket MAX CONNection) as the final parameter to listen.No we don't, not unless we want to drive the kernel crazy and waste huge amounts of memory. SOMAXCONN is 0x7fffffff. The usual size for the backlog queue is a few hundred.when a connection request received, listen will returnlisten returns immediately whether there is a connection request or not.//Now we can start listening (allowing as many connections as possible to //be made at the same time using SOMAXCONN). You could specify any //integer value equal to or lesser than SOMAXCONN instead for custom //purposes).

The function will not //return until a connection request is //madeComplete nonsense.If you compile and run this code, as mentioned before, your program will freeze until a connection request is made.Complete and utter nonsense. Obviously you never even tried it.Because using blocking functions such as listen is so impracticalIt isn't a blocking function and it isn't impractical. I'm obliged to keep repeating myself here because you have repeated the error so often that it requires attention called to it.making a socket asynchronous simply requires an additional line of code after the listen function.A moment's thought should have revealed to you that this implies that listen does not block.Do read the documentation some time, for heaven's sake. So MSDN is wrong as well.

Socket Program For Echo Ping Talk Commands In C 5

Try it and see. NB you have also confused 'asynchronous' with 'non-blocking'. You also haven't addressed all the other points I made. Your notion of a 'thread stretched from one computer to another' is ridiculous: that's a connection.

A thread is a unit of execution in one computer. Port numbers are not there to distinguish sockets from threads.

There is no 'network computer', there is a network byte order, which is simply a standard. You cannot 'replace the listen function with asynchronous sockets', and the code you've posted doesn't actually do so. It still has the listen function, and the changes start afterwards, which proves it doesn't block. You've misdescribed the second parameter to listen. You have confused listen with accept almost throughout. The server cannot 'decide whether or not to accept the connection': it has already been accepted by the TCP stack and placed on the backlog queue.

That's what the backlog queue is for, and the backlog parameter to listen; and it is also why the client can connect before the server calls accept. Now that you've had several more years experience I suggest you reread your article, and fix it. It needs it, badly. Dilip K Sharma 27-Mar-Mar-13 21:15It's a very good article to understand basics of Socket programming with windows.But, could have been better, if you had talked about Socket programming with Unix.Can a Windows server/client talk to Unix Client/Server.What are the changes we need to do in the existing code, given by you, to do the same in Unix.Thanks,Dilip SharmaLast Visit: 12-Jan-20 18:35 Last Update: 12-Jan-20 18:351General News Suggestion Question Bug Answer Joke Praise Rant AdminUse Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

. Hadri RahmanI got the multithreaded code to work, but when I send a message using the client, I get this:$./echoclient.outSocket createdConnectedEnter message: HelloServer reply:Hi There! I’m the connection handler.Type the message and the server shall repeat it.Enter message: HelloServer reply:Hellohere! I’m the connection handler.Type the message and the server shall repeat it.Enter message: HelpServer reply:Hellohere!

I’m the connection handler.Type the message and the server shall repeat it.Enter message: this is stupidServer reply:Helpohere! I’m the connection handler.Type the message and the server shall repeat it.Enter message: Server reply:thisisere! I’m the connection handler.Type the message and the server shall repeat it.Enter message: Server reply:stupidere! I’m the connection handler.Type the message and the server shall repeat it.Any idea what to do?. MartinI solved that issue adding a “+1″ after every use of the function strlen, i.e.write(clientsock, clientmessage, strlen(clientmessage) + 1);strlen returns the length of the c string omitting the the terminating null character, so write sends the string without it. You receive it fine in the receive buffer, but when you try to read from it you read all the characters from the beginning of buffer until it finds a random occurring null character.

Socket Program For Echo Ping Talk Commands In Computer

You could null out your buffer before reading or writing like so:memset(clientmessage,”n”,sizeof(clientmessage));I think sending the null character is simpler. jimmyHi Silver,first of all thanks a lot for sharing this. I really appreciate it, so thanks again.Here come my questions, just in order to clarify:1.

You declare newsock as a pointer and dynamically allocate e new byte each time a new client connects. Why didn’t you just declared it as a normal int, assigning the pointer to clientsock as you already did?2.

Snifferthread is only declared once and no dynamic allocation happens after a client connects, so I assume more than one thread (or threadhandler) can refer to the same pthreadt variable without any influence on the previously created/started threads. Am I right?3. When passing arguments to the thread handler function (I see you pass the new socket variable as a pointer), these become thread variables, thus are not shared by the different threads, am I right?4. This would also be valid if passing a client address to the thread handler, thus it would not affect the client address of any other connection handled by the other threads, right?Again, thanks a lot for the code snippet.well, the thread handling shown in the code, may not be fully correct, I just wrote it as an experiment and it worked.1. I created newsock as a pointer to allocate memory separately for each thread, otherwise it would get overwritten across threads.2. The snifferthread (should have named it something better) variable is created everytime in the while loop, so a new one gets created for every client.

Socket Program For Echo Ping Talk Commands In C 3

Its address is the first parameter to pthreadcreate function.3. Not exactly, the newsock is created by doing a malloc(1); in the main thread, so a new one is created for every thread.4. You can pass any custom structure variable to the thread function and store anything in it. Like create a struct, fill it in the main thread with socket pointer, address variables, and then pass to thread. Just make sure that in the main thread it does not get over-written (by using malloc for example).

jimmyHi Silver,thanks once again for the prompt answer. You are right for what concerns point 4: as long as the thread copies the passed struct in an own local struct, so it gets not over-written by the next thread operation, everything should be fine.Still, for what concerns points 1 to 3, I’m not quite sure the dynamic allocation was the best choice and also the constant declaration of a new pthreadt var in the while loop sounds a little weird to me.

I compared a couple of other threaded server sources and many of them declare the newsock variable as a global one, passing it as an argument and not caring anymore about it (as it gets copied in a local thread variable) and only declare the pthreadt var once (in the main function variables). It then gets handled by the OS (?) in order to create all the needed and independent threadsas far as I got. Am I missing something or did I get it right?Thanks again for the clarifications.I gave the code a little thought.

Your arguments are probably right.Since we are accept and create a thread for only 1 incoming connection at a time, it is okay to use the same newsock and pthreadt variable. The thread would create its local copy of newsock and work fine.I guess its all right to declare pthreadt variable only once and reuse it.According to###Before returning, a successful call to pthreadcreate stores the IDof the new thread in the buffer pointed to by thread; this identifieris used to refer to the thread in subsequent calls to other pthreadsfunctions.###Therefore you can use the same variable again and again.I wrote another version of the server following your ideas and it works fine.