06Linux Socket Demo (Tcp 长连接)

服务器端代码：server.c

服务器，启动后，就处于 监听状态
每当有一个客户端进行连接时，server 都会单独 fork() 一个子进程， 在子进程中，进行具体的数据收发处理

// server.c

#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <netinet/in.h>
#include <linux/ipc.h>
#include <linux/msg.h>
#include <sys/types.h>
#define MYPORT 6666
#define MYIP "192.168.45.11"

  // 定义信息传输的格式

struct msg{
    long mtype;
    int cmd;
    char s[3000];
};
struct msg m1,m2;

int main()
{
    pid_t pid;
    int sock;
    int conn;
    int addrlen;
    int ret;
    int opt;
    int optlen;
    struct sockaddr_in addr;


    memset(&addr, 0x0, sizeof(addr));
    addr.sin_family=AF_INET;
    addr.sin_port=htons(MYPORT);
    addr.sin_addr.s_addr=htonl(INADDR_ANY);

    sock=socket(PF_INET, SOCK_STREAM, 0);
    if(sock<0)
    {
        perror("socket"); return(-1);
    }

    /*绑定端口前，清除之前的绑定*/
    opt=1;
    optlen=sizeof(opt);
    setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &opt, optlen);

    /* the next is bind the port */
    ret=bind(sock, (struct sockaddr *)&addr, sizeof(struct sockaddr));
    if(ret)
    {
        perror("bind"); return(-1);
    }
    ret=listen(sock, 5);
    if(ret)
    {
        perror("listen"); return(-1);
    }

    while(1)
    {
        conn=accept(sock, (struct sockaddr *)&addr, &addrlen);
        if(conn<0)
        {
            perror("accept");
            break;
        }
        pid=fork();
        if(pid==0)
        {    /* children */
            close(sock);
            ret=read(conn, &m1, sizeof(struct msg));

            disp(&m1);
            msg_contrl();
            write(conn, &m2, sizeof(struct msg));
            fflush(stdout);
            close(conn);
            exit(0);
        }
        close(conn);
    }
}


disp(struct msg *m)
{
    printf("\nreceive from client:\n");
    printf("\nm.cmd=%d",m->cmd);
    printf("\n---------------------------------------\n");
    fflush(stdout);
    return(0);
}
msg_contrl()
{
        int msgid1;
        key_t key1;
        m1.mtype=1234;
        key1=ftok("/tmp",'b');
        msgid1=msgget(key1, IPC_CREAT|0666);
        msgsnd(msgid1, &m1, sizeof(struct msg)-sizeof(long),0);



        int msgid2;
        key_t key2;
        m2.mtype=1235;
        key2=ftok("/tmp",'c');
        msgid2=msgget(key2, IPC_CREAT|0666);
        msgrcv(msgid2, &m2, sizeof(struct msg)-sizeof(long),m2.mtype,0);
        //printf("\nm2.s:%s",m2.s);
        //printf("\nm2.cmd:%d",m2.cmd);

        return 0;

}

客户端代码：client.c

// client.c

#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <netinet/in.h>
#define MYPORT 6666
#define MYIP "192.168.45.11"
/* this is set the package form*/
struct msg{
    long mtype;
    int cmd;
    char s[3000];
};
struct msg m1,m2;

int main()
{
    pid_t pid;
    int sock;
    int conn;
    int addrlen;
    int ret;
    struct sockaddr_in addr;

    memset(&addr, 0x0, sizeof(addr));
    addr.sin_family=AF_INET;
    addr.sin_port=htons(MYPORT);
    addr.sin_addr.s_addr=inet_addr(MYIP);

    sock=socket(PF_INET, SOCK_STREAM, 0);
    if(sock<0)
    {
        perror("socket"); return(-1);
    }
    ret=connect(sock, (struct sockaddr *)&addr, sizeof(struct sockaddr));
    if(ret)
    {
        perror("connect");
        return(-1);
    }
    input(&m1);
    write(sock, &m1, sizeof(struct msg));
    read(sock, &m2, sizeof(struct msg));
    display(&m2);
    return 0;

}

//this is what you want to input
input(struct msg *m)
{
    printf("\ncmd:");
    scanf("%d",&m->cmd);
}
display(struct msg *m)
{
    printf("\nrecieved from server:\n");
    printf("\n m.s:%s\n",&m->s);
}