Socket close, socket

Socket close, socket

#include <iostream>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <unistd.h>#include <errno.h>#include <stdio.h>#include <string.h>#include <stdlib.h>bool server(char *ip,int port){    int socketfd = 0;    if(-1 ==(socketfd = socket(AF_INET,SOCK_STREAM,0))){        printf("create socket faile,errno:%d\n",errno);        return false;    }    sockaddr_in serverAddr;    memset(&serverAddr,0,sizeof(serverAddr));    serverAddr.sin_family = AF_INET;    serverAddr.sin_port = htons(port);    serverAddr.sin_addr.s_addr = inet_addr(ip);    if(-1==bind(socketfd,(struct sockaddr *)&serverAddr,sizeof(serverAddr))){        printf("bind socket fail,errno:%d\n",errno);        return false;    }    if(-1==listen(socketfd,10)){        printf("listen socket fail,errno:%d\n",errno);        return false;    }    printf("server has started...\n");    int confd = 0;    sockaddr_in clientAddr;    memset(&clientAddr,0,sizeof(clientAddr));    int sockLen = 0;    if(-1==(confd = accept(socketfd,(struct sockaddr *)&clientAddr,(socklen_t*)&sockLen))){        printf("accept socket fail,errno:%d\n",errno);        return false;    }    int len = 0;    while(1){        char recvBuf[64]={0};        len = recv(confd,recvBuf,sizeof(recvBuf),0);        printf("len:%d,str:%s\n",len,recvBuf);        if(len ==0){            printf("client shutdown socket...\n");            break;        }    }    while(1){        sleep(3);    }    return true;}bool client(char *ip,int port){    int socketfd = 0;    if(-1 == (socketfd = socket(AF_INET,SOCK_STREAM,0))){        printf("create socket fail,errno:%d\n",errno);        return false;    }    sockaddr_in serverAddr;    memset(&serverAddr,0,sizeof(serverAddr));    serverAddr.sin_family = AF_INET;    serverAddr.sin_port = htons(port);    serverAddr.sin_addr.s_addr = inet_addr(ip);    if(-1==connect(socketfd,(struct sockaddr*)&serverAddr,sizeof(serverAddr))){        printf("connect socket fail,errno:%d\n",errno);        return false;    }    char * sendBuf = "hello world";    send(socketfd,sendBuf,strlen(sendBuf)+1,0);    while(1){        sleep(3);    }    return true;}int main(int argc, char *argv[]){    if(argc!=4){        printf("usage:CloseWaitTest [0|1] ip port. 0:server,1:client\n");        return 1;    }    if(atoi(argv[1])==0){        server(argv[2],atoi(argv[3]));    }    if(atoi(argv[1])==1){        client(argv[2],atoi(argv[3]));    }    return 0;}

Test 1: the connection is closed when the process exits. If the client process is shut down normally, the server will receive a request from the client. The connection socket status of the server enters CLOSE_WAIT. Because the server does not actively send a request to close the client, the client socket status is in FIN_WAIT2.

Normal Operation

The listening socket on the server side is in the LISTEN state, and the direct connection socket between the server and client is in the ESTABLISHED state.

Ctrl + c Exit the client

The server socket is in the CLOSE_WAIT state, and the client process socket is in the FIN_WAIT2 state. After the FIN_WAIT2 times out, the system recycles the socket resource. The default timeout value is 60 seconds, you can view it through/sbin/sysctl-a | grep fin_timeout.

The server has not been active, so it is always in the CLOSE_WAIT status.

 

Test 2: