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Top Forums Programming Linux BSD sockets blocking issue Post 302222186 by johnmb on Wednesday 6th of August 2008 07:19:41 AM
Old 08-06-2008
my code

The following is my code for both server and client sockets: -
Code:
    bzero(&sa,sizeof(struct sockaddr_in)); /* clear our address */ 

    if (master) {

        if (gethostname(myname,MAXHOSTNAME) < 0) std::cerr << "Error hostname: " << myname; /* who are we? */ 
        hp= gethostbyname(myname); /* get our address info */     

        if (hp != NULL)  { 
            sa.sin_family= hp->h_addrtype; /* this is our host address */ 
            sa.sin_port= htons(port); /* this is our port number */ 
        }

        if ((s= socket(AF_INET,SOCK_STREAM,0)) >= 0)  {          /* create socket */  

            int on = 1;
            setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); 

            if (bind(s, reinterpret_cast<struct sockaddr*>(&sa), sizeof sa) >= 0)  {    /* bind address to socket */ 

                listen(s, 3); /* max # of queued connects */ 
                established = true;
                master_socket_ref = s;

                int flags = fcntl(master_socket_ref, F_GETFL, 0);
                fcntl(master_socket_ref, F_SETFL, flags | O_NONBLOCK | O_NOCTTY | O_NDELAY | O_RDWR | O_ASYNC); 

            }
            else close(s);
        } 
    }
    else {

        if ((hp= gethostbyname(node_name(node_ref).c_str())) != NULL)  {
  
            bzero(&sa,sizeof(sa)); 
            bcopy(hp->h_addr, (char *)&sa.sin_addr, hp->h_length); /* set address */ 

            sa.sin_family= hp->h_addrtype; 
            sa.sin_port= htons(port); 

            if ((s= socket(hp->h_addrtype,SOCK_STREAM,0)) >= 0)  {   /* get socket */ 

                int on = 1;
                setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); 

                if (connect(s, reinterpret_cast<struct sockaddr*>(&sa), sizeof sa) >= 0)  {       /* Connect */
                    established = true;
                    socket_ref = s;

                    int flags = fcntl(socket_ref, F_GETFL, 0);
                    fcntl(socket_ref, F_SETFL, flags | O_NONBLOCK | O_NOCTTY | O_NDELAY | O_RDWR | O_ASYNC); 
                }
                else close(s);   
            }
        }
    }

If I have set up a server listening socket using the above code, I accept a client as follows :-
Code:
    getsockname(master_socket_ref, reinterpret_cast<struct sockaddr*>(&isa), reinterpret_cast<socklen_t*>(&i));           /* for accept() */ 

    int on = 1;
    socket_ref = accept(master_socket_ref, reinterpret_cast<struct sockaddr*>(&isa), reinterpret_cast<socklen_t*>(&i));
    setsockopt(socket_ref, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); 

    int flags = fcntl(socket_ref, F_GETFL, 0);
    fcntl(socket_ref, F_SETFL, flags | O_NONBLOCK | O_NOCTTY | O_NDELAY | O_RDWR | O_ASYNC);


Last edited by jim mcnamara; 08-06-2008 at 08:22 AM.. Reason: please use code tags
 

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SOCKETPAIR(2)						     Linux Programmer's Manual						     SOCKETPAIR(2)

NAME
socketpair - create a pair of connected sockets SYNOPSIS
#include <sys/types.h> /* See NOTES */ #include <sys/socket.h> int socketpair(int domain, int type, int protocol, int sv[2]); DESCRIPTION
The socketpair() call creates an unnamed pair of connected sockets in the specified domain, of the specified type, and using the optionally specified protocol. For further details of these arguments, see socket(2). The descriptors used in referencing the new sockets are returned in sv[0] and sv[1]. The two sockets are indistinguishable. RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately. ERRORS
EAFNOSUPPORT The specified address family is not supported on this machine. EFAULT The address sv does not specify a valid part of the process address space. EMFILE Too many descriptors are in use by this process. ENFILE The system limit on the total number of open files has been reached. EOPNOTSUPP The specified protocol does not support creation of socket pairs. EPROTONOSUPPORT The specified protocol is not supported on this machine. CONFORMING TO
4.4BSD, POSIX.1-2001. The socketpair() function call appeared in 4.2BSD. It is generally portable to/from non-BSD systems supporting clones of the BSD socket layer (including System V variants). NOTES
On Linux, the only supported domain for this call is AF_UNIX (or synonymously, AF_LOCAL). (Most implementations have the same restric- tion.) Since Linux 2.6.27, socketpair() supports the SOCK_NONBLOCK and SOCK_CLOEXEC flags described in socket(2). POSIX.1-2001 does not require the inclusion of <sys/types.h>, and this header file is not required on Linux. However, some historical (BSD) implementations required this header file, and portable applications are probably wise to include it. SEE ALSO
pipe(2), read(2), socket(2), write(2), socket(7), unix(7) COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2008-10-11 SOCKETPAIR(2)
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