Linux socket program Demo1(client & server)

client  and  server Demo of socket.

client send data to server.

server send data to client.

// this is client

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

#define BUFF_SIZE  1024

int main(int argc, char* argv[])
{
    if(argc<=)
    {
        printf("usage:%s ip_address port_number \r\n", basename(argv[]));
        return ;
    }

    char* ip = argv[];
    int port = atoi(argv[]);

    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    address.sin_port = htons(port);
    inet_pton(AF_INET,ip, &address.sin_addr);

    int sockfd = socket(PF_INET, SOCK_STREAM, );
    assert(sockfd>=);

    struct sockaddr_in client;

    int connfd = connect(sockfd, (struct sockaddr*)&address, sizeof(address));
    if(connfd < )
    {
        printf("errno is : %d...connection failed.\r\n", errno );
    }
    else
    {        

        printf("client:----send-----start\r\n");
        char  data1[] = "C2S:hello server..";
        char  data2[] = "C2S:I am client.";
        char  data3[] = "C2S:centos6 system.Bye-Bye";
        send(sockfd, data1, strlen(data1)+, );
        sleep();
        send(sockfd, data2, strlen(data2)+, );
        sleep();
        send(sockfd, data3, strlen(data3)+, );
        sleep();
        printf("client:----send-----finish\r\n");

        printf("client:----recv-----start\r\n");
        char buffer[BUFF_SIZE];
        memset(buffer, '\0', sizeof(buffer));
        int ret = recv(sockfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);

        memset(buffer, '\0', sizeof(buffer));
        ret = recv(sockfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);

        memset(buffer, '\0', sizeof(buffer));
        ret = recv(sockfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);
        printf("client:----recv-----finish\r\n");

        //==========================================

        buffer[BUFF_SIZE];
        memset(buffer, '\0', sizeof(buffer));
        ret = recv(sockfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);

        memset(buffer, '\0', sizeof(buffer));
        ret = recv(sockfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);

        memset(buffer, '\0', sizeof(buffer));
        ret = recv(sockfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);

        close(connfd);
    }

    printf("-----connect closed----\r\n");

    close(sockfd);

    return ;
}

this is  server:

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

#define BUFF_SIZE  1024

int main(int argc, char* argv[])
{
    if(argc<=)
    {
        printf("usage:%s ip_address port_number \r\n", basename(argv[]));
        return ;
    }

    char* ip = argv[];
    int port = atoi(argv[]);

    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    address.sin_port = htons(port);
    inet_pton(AF_INET,ip, &address.sin_addr);

    int sockfd = socket(PF_INET, SOCK_STREAM, );
    assert(sockfd>=);

    int ret = bind(sockfd,(struct sockaddr*)&address, sizeof(address));
    assert(ret!=-);

    ret = listen(sockfd,);
    assert(ret!=-);

    struct sockaddr_in client;
    socklen_t client_addlength = sizeof(client);
    int connfd = accept(sockfd, (struct sockaddr*)&client, &client_addlength);
    if(connfd < )
    {
        printf("errno is : %d\r\n", errno );
    }
    else
    {
        printf("server:----recv-----start\r\n");
        char buffer[BUFF_SIZE];
        memset(buffer, '\0', sizeof(buffer));
        int ret = recv(connfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);

        memset(buffer, '\0', sizeof(buffer));
        ret = recv(connfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);

        memset(buffer, '\0', sizeof(buffer));
        ret = recv(connfd,buffer,sizeof(buffer)-,);
        printf("get %d bytes. data:[%s]\r\n", ret, buffer);
        printf("server:----recv-----finish\r\n");
        sleep();

        printf("server:----send-----start\r\n");
        char  data1[] = "S2C:hello client..";
        char  data2[] = "S2C:I am server.";
        char  data3[] = "S2C:centos7 system.Bye-Bye";
        send(connfd, data1, strlen(data1)+, );

        sleep();
        send(connfd, data2, strlen(data2)+, );
        sleep();
        send(connfd, data3, strlen(data3)+, );
        sleep();
        printf("server:----send-----finish\r\n");

        //========================================       

        close(STDOUT_FILENO);
        dup(connfd);  //N messages , once recv.
        printf("S2C:==dup==I am server.centos7.");
        printf("S2C:==dup==Hello client...");
        printf("S2C:==dup==bye-bye.");

        close(connfd);
    }

    printf("server----------connection closed--------");

    close(sockfd);

    return ;
}