Address already in use

 

When the client is connected to the server, the server is disconnected and the server is started, the following error occurs: address already in USR.
You can use netstat-anp | more to see that the client is still connected to the server (the port of the Server Bind is still used ). This is because the client does not execute close, and the connection will wait for the client's Fin package for a while. The solution is to use setsockopt so that the socket can be reused, which is the most common Server programming point. The specific method is to add a socket setting between the socket call and the bind Call:
Int opt = 1;
Setsockopt (socket_fd, sol_socket, so_reuseaddr, & OPT, sizeof (OPT ));
Appendix: setsockopt usage.

Setsockopt (set socket status)
Related functions
Getsockopt
Header file
# Include <sys/types. h>;
# Include <sys/socket. h>;
Define functions
Int setsockopt (int s, int level, int optname, const void * optval, socklen_toptlen );
Function Description
Setsockopt () is used to set the socket status specified by parameter S. The level parameter indicates the network layer to be set. It is generally set to sol_socket to access the socket layer. The optname parameter indicates the option to be set, which has the following values:
So_debug enable or disable the troubleshooting Mode
So_reuseaddr allows repeated use of local addresses during the BIND () Process
So_type returns the socket format.
So_error: the cause of the socket error is returned.
Do not transmit data packets sent by so_dontroute using routing devices.
So_broadcast is transmitted through broadcast.
So_sndbuf
So_rcvbuf: set the size of the temporary storage area for receiving
So_keepalive regularly determines whether the connection is terminated.
So_oobinline is immediately sent to the standard input device when OOB data is received
So_linger ensures secure and reliable data transmission.
Parameters
Optval indicates the value to be set, and optlen indicates the length of optval.
Return Value
If the call succeeds, 0 is returned. If an error exists,-1 is returned. The error cause is stored in errno.
Additional instructions
The ebadf parameter S is not a valid socket processing code.
The enotsock parameter S is a file description, not a socket
The option specified by the enoprotoopt parameter optname is incorrect.
The efault parameter optval Pointer Points to the memory space that cannot be accessed.

 

From:Http://dev.firnow.com/course/6_system/linux/Linuxjs/2008630/129368.html

Www.firnow.com time: 2008-06-30 Author: anonymous name Edit:Http://www.firnow.com/