Notes How to determine the client socket disconnection in a Linux server

Here's a list of ways to judge if the remote has been disconnected: (from http://blog.csdn.net/god2469/article/details/8801356)

Law One:

When the recv () return value is less than or equal to 0 o'clock, the socket connection is broken. But also need to determine whether errno equals eintr, if errno = = Eintr that the recv function is because the program received the signal returned, the socket connection is normal, should not close the socket connection.

Law II:

struct Tcp_info info;
int len=sizeof (info);
GetSockOpt (sock, Ipproto_tcp, Tcp_info, &info, (socklen_t *) &len);
if ((info.tcpi_state==tcp_established)) indicates that the else fracture is not disconnected

Fahsarm

If a system function such as SELECT is used, if the remote disconnects, select returns 1,RECV returns 0 to disconnect. Other considerations are the same as law I.

Law IV:

int keepAlive = 1; Turn on the KeepAlive property
int keepidle = 60; If the connection does not have any data in 60 seconds, the probe
int keepinterval = 5; The time interval for the packet to be detected is 5 seconds
int keepcount = 3; The number of attempts to probe. If the 1th probe packet receives a response, it will not be sent 2 times.

SetSockOpt (RS, Sol_socket, so_keepalive, (void *) &keepalive, sizeof (KEEPALIVE));
SetSockOpt (RS, Sol_tcp, Tcp_keepidle, (void*) &keepidle, sizeof (Keepidle));
SetSockOpt (RS, Sol_tcp, TCP_KEEPINTVL, (void *) &keepinterval, sizeof (Keepinterval));
SetSockOpt (RS, Sol_tcp, tcp_keepcnt, (void *) &keepcount, sizeof (Keepcount));

When set, if disconnected, fails immediately when using the socket to read and write, and returns a etimedout error

Law V:

Self-realization of a heartbeat detection, not received within a certain time the custom heartbeat package is marked as disconnected.

Notes How to determine the client socket disconnection in a Linux server