Linux c==網絡編程、循環服務器、併發服務器、I/O多路轉接

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netdb.h>

#define PORT 3333
#define MAX_SIZE 1024

int main()
{
    int sockfd;
    int new_fd;

    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;

    int n_read;
    int ser_size;
    int opt = 1;

    char buffer[MAX_SIZE];

    if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
    {
        perror("socket error!\n");
    exit(1);
    }

    printf("socket success.............!\n");

    if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt)) < 0)
    {
        perror("set socket option error!\n");
    exit(1);
    }

    bzero(&server_addr,0);
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = inet_addr("192.168.1.10"); 

    if(bind(sockfd,(struct sockaddr *)&server_addr,sizeof server_addr) < 0)
    {
        perror("bind error!\n");
    exit(1);
    }

    printf("bind success.............!\n");
    listen(sockfd,5);

    printf("listen success.............!\n");

    printf("accepting..................!\n");

    while(1)
    {
        ser_size = sizeof client_addr;

        if((new_fd = accept(sockfd,(struct sockaddr *)&client_addr,&ser_size)) < 0)
        {
            perror("accept error!\n");
        exit(1);
        }

        printf("accept success.................!\n");

    //read\recv

        printf("reading............!\n");
        n_read = read(new_fd,buffer,sizeof(buffer));

        if(n_read < 0)
        {
            perror("read client msg error!\n");
        exit(1);
        }

        buffer[n_read] = '\0';

        printf("recv msg = %s\n",buffer);
    }

    return 0;
}

客戶端：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

#define PORT 3333
#define MAX_SIZE 1024

int main(int argc, char *argv[])
{
    if(argc != 2)
    {
        printf("Please input server ip!\n");
    exit(1);
    }

    int sockfd;
    int n_write;

    struct sockaddr_in server_addr;

    char buffer[MAX_SIZE];

    if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
    {
        perror("client socket error!\n");
    exit(1);
    }

    bzero(&server_addr,0);

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = inet_addr(argv[1]);

    if(connect(sockfd,(struct sockaddr *)&server_addr,sizeof server_addr) < 0)
    {
        perror("connect server error!\n");
    exit(1);
    }

    while(1)
    {
        memset(buffer,0,sizeof(buffer));
    printf("Please input send msg:\n");
        gets(buffer);

        n_write = write(sockfd,buffer,strlen(buffer));

    if(n_write == -1)
    {
        perror("send to server msg error!\n");
        exit(1);
    }
    }

    return 0;
}

缺點：只能接收到一個客戶端，且等待其結束後才能接受下一個客戶端

併發服務器：

服務器：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netdb.h>

#define PORT 3333
#define MAX_SIZE 1024

void * read_msg(void *arg)
{
    int n_read;

    int new_fd = *((int *)arg);

    char buffer[MAX_SIZE];

    printf("new_fd = %d\n",new_fd);

    while(1)
    {
        memset(buffer,0,sizeof(buffer));

    n_read = read(new_fd,buffer,sizeof(buffer));

    if(n_read < 0)
    {
        perror("recv client msg error!\n");
        exit(1);
    }

    if(n_read == 0)
    {
        printf("client is close!!\n");
        close(new_fd);
        pthread_exit(NULL);
    }

    buffer[n_read] = '\0';

    printf("recv msg:%s\n",buffer);
    }
}

int main()
{
    int sockfd;
    int new_fd;

    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;

    int n_read;
    int ser_size;
    int opt = 1;

    char buffer[MAX_SIZE];

    pthread_t id;

    if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
    {
        perror("socket error!\n");
    exit(1);
    }

    printf("socket success.............!\n");

    if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt)) < 0)
    {
        perror("set socket option error!\n");
    exit(1);
    }

    bzero(&server_addr,0);
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = inet_addr("192.168.1.10"); 

    if(bind(sockfd,(struct sockaddr *)&server_addr,sizeof server_addr) < 0)
    {
        perror("bind error!\n");
    exit(1);
    }

    printf("bind success.............!\n");
    listen(sockfd,5);

    printf("listen success.............!\n");

    printf("accepting..................!\n");

    while(1)
    {
        ser_size = sizeof client_addr;

        if((new_fd = accept(sockfd,(struct sockaddr *)&client_addr,&ser_size)) < 0)
        {
            perror("accept error!\n");
        exit(1);
        }

        printf("accept success.................!\n");

    pthread_create(&id,NULL,read_msg,&new_fd);
    }

    return 0;
}

客戶端：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

#define PORT 3333
#define MAX_SIZE 1024

int main(int argc, char *argv[])
{
    if(argc != 2)
    {
        printf("Please input server ip!\n");
    exit(1);
    }

    int sockfd;
    int n_write;

    struct sockaddr_in server_addr;

    char buffer[MAX_SIZE];

    if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
    {
        perror("client socket error!\n");
    exit(1);
    }

    bzero(&server_addr,0);

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = inet_addr(argv[1]);

    if(connect(sockfd,(struct sockaddr *)&server_addr,sizeof server_addr) < 0)
    {
        perror("connect server error!\n");
    exit(1);
    }

    while(1)
    {
        memset(buffer,0,sizeof(buffer));
    printf("Please input send msg:\n");
        gets(buffer);

        n_write = write(sockfd,buffer,strlen(buffer));

    if(n_write == -1)
    {
        perror("send to server msg error!\n");
        exit(1);
    }
    }

    return 0;
}

缺點：在客戶端沒有發送數據時，每個線程仍需輪流切換，浪費CPU資源

I/O多路轉接：

服務器：

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

/* 宏定義端口號 */
#define portnumber 8000

#define MAX_LINE 80



int main(void)
{
    int  lfd;
    int cfd;
    int sfd;
    int rdy;

    struct sockaddr_in sin;
    struct sockaddr_in cin;

    int client[FD_SETSIZE];  /* 客戶端連接的套接字描述符數組 */

    int maxi;
    int maxfd;                        /* 最大連接數 */

    fd_set rset;
    fd_set allset;

    socklen_t addr_len;         /* 地址結構長度 */

    char buffer[MAX_LINE];

    int i;
    int n;
    int len;
    int opt = 1;   /* 套接字選項 */

    char addr_p[20];



    /* 對server_addr_in  結構進行賦值  */
    bzero(&sin,sizeof(struct sockaddr_in));   /* 先清零 */
    sin.sin_family=AF_INET;                 //
    sin.sin_addr.s_addr=htonl(INADDR_ANY);  //表示接受任何ip地址   將ip地址轉換成網絡字節序
    sin.sin_port=htons(portnumber);         //將端口號轉換成網絡字節序

    /* 調用socket函數創建一個TCP協議套接口 */
    if((lfd=socket(AF_INET,SOCK_STREAM,0))==-1) // AF_INET:IPV4;SOCK_STREAM:TCP
    {
        fprintf(stderr,"Socket error:%s\n\a",strerror(errno));
        exit(1);
    }
    printf("socket!\n");

    /*設置套接字選項 使用默認選項*/
    setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    /* 調用bind函數 將serer_addr結構綁定到sockfd上  */
    if(bind(lfd,(struct sockaddr *)(&sin),sizeof(struct sockaddr))==-1)
    {
        fprintf(stderr,"Bind error:%s\n\a",strerror(errno));
        exit(1);
    }
    printf("bind!\n");

    /* 開始監聽端口   等待客戶的請求 */
    if(listen(lfd,20)==-1)
    {
        fprintf(stderr,"Listen error:%s\n\a",strerror(errno));
        exit(1);
    }
    printf("listen!\n");
    printf("Accepting connections .......\n");

    maxfd = lfd;                                /*對最大文件描述符進行初始化*/
    maxi = -1;

    /*初始化客戶端連接描述符集合*/
    for(i = 0;i < FD_SETSIZE;i++)
    {
        client[i] = -1;
    }

    FD_ZERO(&allset);                     /* 清空文件描述符集合 */
    FD_SET(lfd,&allset);                    /* 將監聽字設置在集合內 */


    /* 開始服務程序的死循環 */
    while(1)
    {
        rset = allset;
        printf("selecting!\n");
        /*得到當前可以讀的文件描述符數*/
        rdy = select(maxfd + 1, &rset, NULL, NULL, NULL);

        printf("selected!\n");
        if(FD_ISSET(lfd, &rset))
        {

            addr_len = sizeof(sin);
            printf("accepting!\n");
            /* 接受客戶端的請求 */
            if((cfd=accept(lfd,(struct sockaddr *)(&cin),&addr_len))==-1)
            {
                fprintf(stderr,"Accept error:%s\n\a",strerror(errno));
                exit(1);
            }
            printf("accepted!\n");


                     /*查找一個空閒位置*/
            for(i = 0; i<FD_SETSIZE; i++)
            {       //printf("%d\t",client[i]);
                if(client[i] <= 0)
                {
                    client[i] = cfd;   /* 將處理該客戶端的連接套接字設置到該位置 */
                    break;
                }
            }

        /* 太多的客戶端連接   服務器拒絕俄請求  跳出循環 */
            if(i == FD_SETSIZE)
            {
                printf("too many clients");
                exit(1);
            }

            FD_SET(cfd, &allset);     /* 設置連接集合 */

            if(cfd > maxfd)                  /* 新的連接描述符 */
            {
                maxfd = cfd;
            }

            if(i > maxi)
            {
                maxi = i;
            }

            if(--rdy <= 0)                /* 減少一個連接描述符 */
            {
                continue;
            }

        }

        /* 對每一個連接描述符做處理 */
        for(i = 0;i< FD_SETSIZE;i++)
        {
            if((sfd = client[i]) < 0)
            {
                continue;
            }

            if(FD_ISSET(sfd, &rset))
            {
                printf("reading!\n");
                n = read(sfd,buffer,MAX_LINE);
                printf("%s\n",buffer);
                printf("read!\n");
                if(n == 0)
                {
                    printf("the other side has been closed. \n");
                    fflush(stdout);                                    /* 刷新 輸出終端 */
                    close(sfd);

                    FD_CLR(sfd, &allset);                        /*清空連接描述符數組*/
                    client[i] = -1;
                }

                else
                {
                    /* 將客戶端地址轉換成字符串 */
                    inet_ntop(AF_INET, &cin.sin_addr, addr_p, sizeof(addr_p));
                    addr_p[strlen(addr_p)] = '\0';

                    /*打印客戶端地址 和 端口號*/
                    printf("Client Ip is %s, port is %d\n",addr_p,ntohs(cin.sin_port));


                    /* 諧函數出錯 */
                    if(n == 1)
                    {
                        exit(1);
                    }
                }

                /*如果沒有可以讀的套接字   退出循環*/
                if(--rdy <= 0)
                {
                    break;


            }
        }

    }

    close(lfd);       /* 關閉鏈接套接字 */
    return 0;
}

客戶端：

#include <stdlib.h> 
#include <stdio.h> 
#include <errno.h> 
#include <string.h> 
#include <netdb.h> 
#include <sys/types.h> 
#include <netinet/in.h> 
#include <sys/socket.h> 

#define portnumber 8000

int main(int argc, char *argv[]) 
{ 
    int nbytes;
    int sockfd; 
    char buffer[80]; 
    char buffer_2[80];
    struct sockaddr_in server_addr; 
    struct hostent *host; 

    if(argc!=2) 
    { 
        fprintf(stderr,"Usage:%s hostname \a\n",argv[0]); 
        exit(1); 
    } 

    if((host=gethostbyname(argv[1]))==NULL) 
    { 
        fprintf(stderr,"Gethostname error\n"); 
        exit(1); 
    } 

     /* 調用socket函數創建一個TCP協議套接口 */ 
    if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1) // AF_INET:Internet;SOCK_STREAM:TCP
    { 
        fprintf(stderr,"Socket Error:%s\a\n",strerror(errno)); 
        exit(1); 
    } 


    bzero(&server_addr,sizeof(server_addr)); // 
    server_addr.sin_family=AF_INET;
    server_addr.sin_port=htons(portnumber);
    server_addr.sin_addr = *((struct in_addr *)host->h_addr);//?


    if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1) 
    { 
        fprintf(stderr,"Connect Error:%s\a\n",strerror(errno)); 
        exit(1); 
    } 

    while(1){

    printf("Please input char:\n");


    fgets(buffer,1024,stdin); 
    write(sockfd,buffer,strlen(buffer));
       #if 1
    if((nbytes=read(sockfd,buffer_2,81))==-1) 
        { 
            fprintf(stderr,"Read Error:%s\n",strerror(errno));
            exit(1); 
        }

        buffer_2[nbytes]='\0';
        printf("Client received from Server %s\n",buffer_2);
        #endif


    }   
    close(sockfd);
    exit(0); 
}

優點：使用select來充當監管作用

Linux c==網絡編程、循環服務器、併發服務器、I/O多路轉接

併發服務器：

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