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Top Forums Programming Looping connect call for a non blocking socket Post 302705101 by satish@123 on Monday 24th of September 2012 08:41:01 AM
Old 09-24-2012
So connect, select and again connect based on the return codes and errno indications achieve smooth non blocking connection but I am still thinking of looping connect call and I verified the truss to see the return code of connect when I loop -

First remote connect said - EINPROGRESS as expected.
Next try indicated - EISCONN. Indicating already connected.
Even if not then would have indicated EALREADY. Having 100 milli secods each time before trying to connect, there should not be any issue except that the last retry may indicate connect = 0 and will not update errno (The only chance of failure in the loop after 400 milli seconds, mostly in bad network cases). Other case If connect returned 0 will not update errno but the next try to same connected socket would indicate error - EISCONN, correct?

connect(4, 0x080453E0, 16, SOV_DEFAULT) Err#150 EINPROGRESS
pollsys(0x00000000, 0, 0x08045330, 0x00000000) = 0
connect(4, 0x080453E0, 16, SOV_DEFAULT) Err#133 EISCONN
 

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connect(2)							System Calls Manual							connect(2)

Name
       connect - initiate a connection on a socket

Syntax
       #include <sys/types.h>
       #include <sys/socket.h>

       connect(s, name, namelen)
       int s;
       struct sockaddr *name;
       int namelen;

Description
       The  call  initiates  a	connection  on a socket.  The parameter s is a socket.	If the socket is of type SOCK_DGRAM, this call permanently
       specifies the peer to which datagrams are sent.	If it is of type SOCK_STREAM, this call attempts to make a connection to  another  socket.
       The other socket is specified by name, which is an address in the communications space of the socket.  Each communications space interprets
       the name parameter in its own way.  The size of the structure sockaddr is namelen.

Return Values
       If the connection or binding succeeds, then 0 is returned.  Otherwise, a -1 is returned, and a more specific error code is stored in errno.

Diagnostics
       The call fails under the following conditions:

       [EBADF]	      The s is not a valid descriptor.

       [ENOTSOCK]     The s is a descriptor for a file, not a socket.

       [EADDRNOTAVAIL]
		      The specified address is not available on this machine.

       [EAFNOSUPPORT] Addresses in the specified address family cannot be used with this socket.

       [EINPROGRESS]  The connection is requested on a socket with FNDELAY set (using

       [EISCONN]      The socket is already connected.

       [ETIMEDOUT]    Connection establishment timed out without establishing a connection.

       [ECONNREFUSED] The attempt to connect was forcefully rejected.

       [ENETUNREACH]  The network is not reachable from this host.

       [EADDRINUSE]   The address is already in use.

       [EFAULT]       The name parameter specifies an area outside the process address space.

       [EWOULDBLOCK]  The socket is nonblocking, and the connection cannot be completed immediately.  You can select the  socket  for  writing	by
		      using the system call while it is connecting.

       The following errors are specific to connecting names in the ULTRIX domain:

       [ENOTDIR]      A component of the path prefix is not a directory.

       [ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

       [ENOENT]       The named socket does not exist.

       [EACCES]       Search permission is denied for a component of the path prefix.

       [ELOOP]	      Too many symbolic links were encountered in translating the pathname.

See Also
       accept(2), fcntl(2), getsockname(2), select(2), shutdown(2), socket(2)

																	connect(2)
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