Login or Register to Ask a Question and Join Our Community


Programming

write on Non Blocking Socket

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums Programming write on Non Blocking Socket
# 1  
Old 09-06-2010
write on Non Blocking Socket
How to know whether socket is ready for write.
Code:
select(maxfds, (fd_set *)NULL, &writefds, NULL, &timeout);

By default socket is set for write without checking whether it would block or not? If so how do I know my FD is ready for writing.
# 2  
Old 09-07-2010
1. select returns > 0 if there are available sockets

2. FD_ISSET(sock, &writefds) returns true if sock is in the FDSET and the sock descriptor is ready to write. sock is an integer and is one of the sockets you intend to write.
# 3  
Old 09-08-2010
I am connecting to port 7(echo service) in the remote machine.
suppose port 7 is not running in the remote machine I do not want to wait in connect call for long time.. so I am using non blocking connect with timeout of 3 seconds. But I am always getting the return code 1 from select call though the echo service is not running incase of write falgs set.

Code:
x=fcntl(S,F_GETFL,0);
fcntl(s,F_SETFL,x | O_NONBLOCK);
rc=connect(s, (struct sockaddr *)&sin, sizeof(sin));
if( errno == EINPROGRESS)
{        
     FD_ZERO(&writeFDs);
     FD_SET(s, &writeFDs);
     rc=select(maxFDs, (fd_set *) NULL, &writeFDs,  (fd_set *)NULL, 
                                                                (struct timeval *)(&timeout));
     if( rc ==0 || rc == -1)
       printf(" Timed out -- Not connected even after 3 secs wait");
    else
    {
	if(FD_ISSET(s,&writeFDs))
       	write(s,"service",7);
    }
}

In the above FD_ISSET is returning true and when it tries to write it retrun EPIPE, because of not connected. How we decide that service is ready for writing?
# 4  
Old 09-08-2010
Closing this thread - looks basically like a double post to me. Continue here:
non blocking connect
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Programming

Which are blocking and non-blocking api's in sockets in C ?

among the below socket programming api's, please let me know which are blocking and non-blocking. socket accept bind listen write read close (2 Replies)
Discussion started by: VSSajjan
2 Replies

2. Programming

Looping connect call for a non blocking socket

will there be any unexpected results on looping connect call for a non blocking socket to determine the connection based on error code. I am getting connection unsuccessful intermittently and so wondering whether is the timeout 500 millisec not sufficient or looping connect cause any unexpected. ... (7 Replies)
Discussion started by: satish@123
7 Replies

3. Shell Programming and Scripting

Read and write to tcp socket

Hello all, I have a requirement to read and write to a tcp socket from an HP-UX shell script. I see a /dev/tcp character device on my servers: crw-rw-rw- 1 root root 72 0x00004f Mar 28 18:37 /dev/tcp So I believe this is what I should use. The problem is that all the... (2 Replies)
Discussion started by: lupin..the..3rd
2 Replies

4. IP Networking

Clarification - Setting socket options at the same time when socket is listening

I need clarification on whether it is okay to set socket options on a listening socket simultaneously when it is being used in an accept() call? Following is the scenario:- -- Task 1 - is executing in a loop - polling a listen socket, lets call it 'fd', (whose file descriptor is global)... (2 Replies)
Discussion started by: jake24
2 Replies

5. Programming

Write-Write on a socket

Can anyone tell what happens if each end writes at the same time on the same socket ? - if one of them issues a read() after write() has completed, will it record into the buffer what the other sent ? ex. e1 writes to e2 - - - while - - - e2 writes to e1 (at the same time) e1 read () - what... (1 Reply)
Discussion started by: gendaox
1 Replies

6. Programming

socket function to read a webpage (socket.h)

Why does this socket function only read the first 1440 chars of the stream. Why not the whole stream ? I checked it with gdm and valgrind and everything seems correct... #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/stat.h> #include <string.h> #include... (3 Replies)
Discussion started by: cyler
3 Replies

7. UNIX for Advanced & Expert Users

connect problem for sctp socket (ipv6 socket) - Runtime fail Invalid Arguments

Hi, I was porting ipv4 application to ipv6; i was done with TCP transports. Now i am facing problem with SCTp transport at runtime. To test SCTP transport I am using following server and client socket programs. Server program runs fine, but client program fails giving Invalid Arguments for... (0 Replies)
Discussion started by: chandrutiptur
0 Replies

8. IP Networking

Can we write a multiple thread to receive from a single socket file descriptor

Hi Friends, I have written a program which will listener for more than 1000 requests per second from a single socket descriptor and then it will process those requestes. Its taking X amount of time. Now i want to reduce that time. Will I can write multiple threads to receive the... (2 Replies)
Discussion started by: pa.chidhambaram
2 Replies

9. Programming

How to Write Linux Friendly Async Socket I/O

I am presently refactoring a windows deamon with an eye towards porting it to linux someday. Presently the application uses a single background thread and asynchronous socket I/O to implement FTP and HTTP clients in a single switch statement (2000 lines and 100 cases just for the switch... (3 Replies)
Discussion started by: siegfried
3 Replies

10. Programming

read/write socket error

I have client and server connected. client write and read from csock. server write and read from ssock suppose the server does : .... close(ssock); //send FIN to client othertask(); .... READ ERROR if after the server close() the client does: ... read(csock,...); ...... (2 Replies)
Discussion started by: gio
2 Replies
Login or Register to Ask a Question