网络编程：OSI协议，TCP/IP协议，IP地址，UDP编程

目录

国际网络通信协议标准：

1.OSI协议：

 2.TCP/IP协议模型：

 应用层  ：

 传输层：

  网络层：             IPV4协议            IP地址

 IP地址的划分：            公有地址            私有地址

        MAC地址：

        端口号：

 UDP编程

1.套接字：

2.流程  

3.函数接口

（1） socket

 （2）sendto 

（3） inet_addr

（4） htons 

（5） bind 

（6）recvfrom 

 主机作为发送端

主机作为接收端

 网络：
协议：通信双方约定的一套标准 

国际网络通信协议标准：

1.OSI协议：

 2.TCP/IP协议模型：

 应用层  ：

 传输层：

  网络层： 
            IPV4协议
            IP地址

 IP地址的划分：
            公有地址
            私有地址

        MAC地址：

 设备自带网卡的地址（该地址是唯一的）

        端口号：

 找到同一台主机不同的应用程序

 UDP编程

1.套接字：

        实现Linux系统下的网络通信
        套接字：一次通信对象的抽象

2.流程  

发送端流程：1.创建套接字
               2.发送信息
               3.关闭套接字

    接收端流程： 1.创建套接字       
                2.绑定IP和Port
                3.接收信息 
                4.关闭套接字

3.函数接口

（1） socket

 （2）sendto 

（3） inet_addr

（4） htons 

（5） bind 

（6）recvfrom 

 练习一：

主机作为发送端

#include "../head.h"
//主机作为发送方
int main()
{
    int sockfd=0;
    ssize_t nsize=0;
    struct sockaddr_in recvaddr;
    struct sockaddr_in sendaddr;
    //创建用来通信的套接字
    sockfd=socket(AF_INET,SOCK_DGRAM,0);//AF_INET：IPV4协议族，SOCK_DGRAM：UDP数据报套接字
    if(sockfd==-1)
    {
        perror("failed to socket");
        return -1;
    }
    //将发送端套接字与IP地址和端口号绑定
    sendaddr.sin_family=AF_INET;
    sendaddr.sin_port=htons(30000);
    sendaddr.sin_addr.s_addr=inet_addr("192.168.0.185");
    bind(sockfd,(struct sockaddr *)&sendaddr,sizeof(sendaddr));

    //为目的地址赋值
    recvaddr.sin_family=AF_INET;//协议族为IPV4
    recvaddr.sin_port=htons(8080);//端口号（ htons() 将本地字节序（小端）转换为网络字节序（大端））（发送给wltszs4.3.29网络调试助手）
    recvaddr.sin_addr.s_addr=inet_addr("192.168.0.135");//IP地址（ inet_addr() 将字符串类型转换为二进制地址类型）
    
    //向目的地址发送数据
    nsize=sendto(sockfd,"66666666666",12,0,(struct sockaddr *)&recvaddr,sizeof(recvaddr));//注意强制类型转换
    if(nsize==-1)
    {
        perror("failed to sendto");
        return 0;
    }
    printf("发送成功\n");
    //关闭套接字
    close(sockfd);
    return 0;
}

主机作为接收端

#include "../head.h"
int main()
{

    int sockfd=0;
    int ret=0;
    char tmpbuff[200]={0};
    ssize_t nsize=0;
    struct sockaddr_in recvaddr;
    //创建套接字
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd==-1)
    {
        perror("failed to socket");
        return -1;
    }
    //将套接字和IP地址与端口号绑定
    recvaddr.sin_family=AF_INET;
    recvaddr.sin_port=htons(20000);
    recvaddr.sin_addr.s_addr=inet_addr("192.168.0.185");
    ret=bind(sockfd,(struct sockaddr *)&recvaddr,sizeof(recvaddr));

    if(ret==-1)
    {
        perror("failed to bind");
        return 0;
    }
    //接受数据
    nsize=recvfrom(sockfd,tmpbuff,sizeof(tmpbuff),0,NULL,NULL);
    if(nsize==-1)
    {
        perror("failed to recvfrom");
        return 0;
    }
    //打印数据
    printf("接收到字节数:%ld,内容为:%s\n",nsize,tmpbuff);
    //关闭套接字
    close(sockfd);
    return 0;
}

练习二：利用UDP编程发送文件

发送端send.c

#include "../head.h"
int main()
{
    int sockfd;
    int ret=0;
    FILE *fp=NULL;
    struct sockaddr_in recvaddr;
    char readbuff[1024]={0};
    size_t size=0;
    ssize_t nsize=0;

   //创建套接字
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd==-1)
    {
        perror("failed to socket");
        return -1;
    }
    
    //为目的地址赋值
    recvaddr.sin_family=AF_INET;
    recvaddr.sin_port=htons(30000);
    recvaddr.sin_addr.s_addr=inet_addr("192.168.0.187");
    //输入要发送的文件名
    printf("请输入要发送的文件名：");
    fgets(readbuff,sizeof(readbuff),stdin);
    readbuff[strlen(readbuff)-1]='\0';
    //打开该文件
    fp=fopen(readbuff,"r");
    if(fp==NULL)
    {
        perror("failed to fopen send.txt");
        return -1;
    }
    
   //发送文件名
    nsize=sendto(sockfd,readbuff,strlen(readbuff)+1,0,(struct sockaddr *)&recvaddr,sizeof(recvaddr));
     if(nsize==-1)
    {
         perror("failed to sendto");
         return -1;
    }
//发送文件内容
while(1)
{
     size=fread(readbuff,1,sizeof(readbuff),fp);
     if(size<=0)
     {
        break;
     }
     nsize=sendto(sockfd,readbuff,size,0,(struct sockaddr *)&recvaddr,sizeof(recvaddr));
     if(nsize==-1)
    {
         perror("failed to sendto");
         return -1;
    }
}
//发送文件结尾关闭标志
    sprintf(readbuff,".quit");
    nsize=sendto(sockfd,readbuff,size,0,(struct sockaddr *)&recvaddr,sizeof(recvaddr));
     if(nsize==-1)
    {
         perror("failed to sendto");
         return -1;
    }
   //关闭套接字和文件
    close(sockfd);
    fclose(fp);
    return 0;  
   
}

接收文件端

#include "../head.h"
int main()
{
    int sockfd;
    int ret=0;
    FILE *fp=NULL;
    char filename[100]={0};
    char tmpbuff[1024]={0};
    struct sockaddr_in recvaddr;
    char readbuff[1024]={0};
    size_t size=0;
    ssize_t nsize=0;

   //创建套接字
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd==-1)
    {
        perror("failed to socket");
        return -1;
    }
    
   //绑定接收IP地址和套接字，端口号
    recvaddr.sin_family=AF_INET;
    recvaddr.sin_port=htons(30000);
    recvaddr.sin_addr.s_addr=inet_addr("192.168.0.187");
    bind(sockfd,(struct sockaddr *)&recvaddr,sizeof(recvaddr));
   //接收文件名
    nsize=recvfrom(sockfd,filename,sizeof(filename),0,NULL,NULL);
    if(nsize==-1)
    {
        perror("failed to recvfrom");
        return -1;
    }
    //创建文件
     fp=fopen(filename,"w");
    if(fp==NULL)
    {
        perror("failed to fopen");
        return -1;
    }
    //接收文件内容
    while (1)
    {
         nsize=recvfrom(sockfd,tmpbuff,sizeof(tmpbuff),0,NULL,NULL);
         if(nsize==0)
        {
            
            break;
        }
        if(!strcmp(tmpbuff,".quit"))
        {
            break;
        }
        fwrite(tmpbuff,nsize,1,fp);
    }
    //关闭套接字和文件
    close(sockfd);
    fclose(fp);
    return 0;  
   
}

练习三：利用UDP编程实现聊天功能

1.(进程实现)

send.c

#include "../head.h"
int main()
{
    pid_t pid;
    struct sockaddr_in sendaddr;
    struct sockaddr_in recvaddr;
    char tmpbuff[100]={0};
    ssize_t size_send;
    ssize_t size_recv;
    int sockfd=0;
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd==-1)
    {
        perror("failed to socket");
        return -1;
    }
    recvaddr.sin_family=AF_INET;
    recvaddr.sin_port=htons(30000);
    recvaddr.sin_addr.s_addr=inet_addr("192.168.0.187");

//第一次发送是为了建立连接，数据可随机发送，不打印
    size_send = sendto(sockfd,"hello",6,0,(struct sockaddr *)&recvaddr,sizeof(recvaddr));
    if(size_send==-1)
    {
        perror("failed to sendto");
        return -1;
    }
    pid=fork();
    if(pid==-1)
    {
        perror("failed to fork");
        return -1;
    }
    if(pid==0)
    {   

        while (1)
        {
                memset(tmpbuff,0,sizeof(tmpbuff));
                fgets(tmpbuff,sizeof(tmpbuff),stdin);
                tmpbuff[strlen(tmpbuff)-1]='\0';
              
                size_send=sendto(sockfd,tmpbuff,strlen(tmpbuff),0,(struct sockaddr *)&recvaddr,sizeof(recvaddr));
                if(size_send==-1)
                {
                    perror("failed to sendto");
                    return -1;
                }
               
                if(!strcmp(tmpbuff,".quit"))
                {
                    
                    break;
                }
               
        }
        kill(getppid(),SIGKILL);

    }
    else if(pid>0)
    {
        while(1)
        {
            memset(tmpbuff,0,sizeof(tmpbuff));
            size_recv = recvfrom(sockfd,tmpbuff,sizeof(tmpbuff),0,NULL,NULL);
            if(size_recv==-1)
            {
                perror("failed to recvfrom");
                return -1;
            }
            if(!strcmp(tmpbuff,".quit"))
            {
                
                break;
            }
            printf("RECV:%s\n",tmpbuff);
        }
        kill(pid,SIGKILL);
         
    }
    close(sockfd);
    return 0;

}

recv.c

#include "../head.h"
int main()
{
    pid_t pid;
    struct sockaddr_in sendaddr;
    struct sockaddr_in recvaddr;
    size_t size_send;
    size_t size_recv;
    char tmpbuff[100]={0};
    socklen_t addrlen=sizeof(sendaddr);
    int ret=0;
    int sockfd=0;
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd==-1)
    {
        perror("failed to socket");
        return -1;
    }
    recvaddr.sin_family=AF_INET;
    recvaddr.sin_port=htons(30000);
    recvaddr.sin_addr.s_addr=inet_addr("192.168.0.187");
    ret=bind(sockfd,(struct sockaddr *)&recvaddr,sizeof(recvaddr));
    if(ret==-1)
    {
        perror("failed to bind");
        return -1;
    }
//第一次接收是为了建立连接，数据不打印
    size_recv = recvfrom(sockfd,tmpbuff,sizeof(tmpbuff),0,(struct sockaddr *)&sendaddr,
   
    if(size_recv==-1)
    {
        perror("failed to recvfrom");
        return -1;
    }

    pid=fork();
    if(pid==-1)
    {
        perror("failed to fork");
        return -1;
    }
    if(pid==0)
    {
        while(1)
        {
             memset(tmpbuff,0,sizeof(tmpbuff));
               size_recv = recvfrom(sockfd,tmpbuff,sizeof(tmpbuff),0,NULL,NULL);
             
            if(size_recv==-1)
            {
                perror("failed to sendto");
                return -1;
            }
            
            if(!strcmp(tmpbuff,".quit"))
            {
                
                break;
            }
            printf("RECV:%s\n",tmpbuff);
        }
     kill(getppid(),SIGKILL);
        
    }
    else if(pid>0)
    {
        while (1)
        {
            memset(tmpbuff,0,sizeof(tmpbuff));
            fgets(tmpbuff,sizeof(tmpbuff),stdin);
            tmpbuff[strlen(tmpbuff)-1]='\0';
            size_send=sendto(sockfd,tmpbuff,strlen(tmpbuff),0,(struct sockaddr *)&sendaddr,sizeof(sendaddr));
            if(size_send==-1)
            {
                perror("failed to sendto");
                return -1;
            }
            if(!strcmp(tmpbuff,".quit"))
            {
              
                break;
            }
           
        }
          kill(pid,SIGKILL);
        
    }
    close(sockfd);
    return 0;


}

2.(线程实现)

send.c

#include "../head.h"

int sockfd = 0;
pthread_t tid1;
pthread_t tid2;
struct sockaddr_in recvaddr;

void *thread1(void *arg)
{
    char tmpbuff[1024] = {0};
    ssize_t nsize = 0;

    while (1)
    {
        memset(tmpbuff, 0, sizeof(tmpbuff));
        fgets(tmpbuff, sizeof(tmpbuff), stdin);
        tmpbuff[strlen(tmpbuff)-1] = '\0';
        
        nsize = sendto(sockfd, tmpbuff, strlen(tmpbuff), 0, (struct sockaddr *)&recvaddr, sizeof(recvaddr));
        if (-1 == nsize)
        {
            perror("fail to sendto");
            return NULL;
        }

        if (!strcmp(tmpbuff, ".quit"))
        {
            break;
        }
    }
    pthread_cancel(tid2);

    return NULL;
}

void *thread2(void *arg)
{  
    char tmpbuff[1024] = {0};
    ssize_t nsize = 0;

    while (1)
    {
        memset(tmpbuff, 0, sizeof(tmpbuff));
        nsize = recvfrom(sockfd, tmpbuff, sizeof(tmpbuff), 0, NULL, NULL);
        if (-1 == nsize)
        {
            perror("fail to recvfrom");
            return NULL;
        }

        if (!strcmp(tmpbuff, ".quit"))
        {
            break;
        }
        
        printf("RECV:%s\n", tmpbuff);
    }
    pthread_cancel(tid1);

    return NULL;
}

int main(void)
{
    //1.创建套接字
    char tmpbuff[1024] = {"hello"};
    ssize_t nsize = 0;

    recvaddr.sin_family = AF_INET;
    recvaddr.sin_port = htons(RECV_PORT);
    recvaddr.sin_addr.s_addr = inet_addr(RECV_IP);

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (-1 == sockfd)
    {
        perror("fail to socket");
        return -1;
    }

    //2.发送一次
    nsize = sendto(sockfd, tmpbuff, strlen(tmpbuff), 0, (struct sockaddr *)&recvaddr, sizeof(recvaddr));
    if (-1 == nsize)
    {
        perror("fail to sendto");
        return -1;
    }

    //3.创建两个线程
    pthread_create(&tid1, NULL, thread1, NULL);
    pthread_create(&tid2, NULL, thread2, NULL);

    pthread_join(tid1, NULL);
    pthread_join(tid2, NULL);

    close(sockfd);

    return 0;
}

recv.c

#include "../head.h"

int sockfd = 0;
pthread_t tid1;
pthread_t tid2;
struct sockaddr_in recvaddr;
struct sockaddr_in sendaddr;

void *thread1(void *arg)
{
    char tmpbuff[1024] = {0};
    ssize_t nsize = 0;

    while (1)
    {
        memset(tmpbuff, 0, sizeof(tmpbuff));
        fgets(tmpbuff, sizeof(tmpbuff), stdin);
        tmpbuff[strlen(tmpbuff)-1] = '\0';
        
        nsize = sendto(sockfd, tmpbuff, strlen(tmpbuff), 0, (struct sockaddr *)&sendaddr, sizeof(sendaddr));
        if (-1 == nsize)
        {
            perror("fail to sendto");
            return NULL;
        }

        if (!strcmp(tmpbuff, ".quit"))
        {
            break;
        }
    }
    pthread_cancel(tid2);

    return NULL;
}

void *thread2(void *arg)
{  
    char tmpbuff[1024] = {0};
    ssize_t nsize = 0;

    while (1)
    {
        memset(tmpbuff, 0, sizeof(tmpbuff));
        nsize = recvfrom(sockfd, tmpbuff, sizeof(tmpbuff), 0, NULL, NULL);
        if (-1 == nsize)
        {
            perror("fail to recvfrom");
            return NULL;
        }

        if (!strcmp(tmpbuff, ".quit"))
        {
            break;
        }
        
        printf("RECV:%s\n", tmpbuff);
    }
    pthread_cancel(tid1);

    return NULL;
}

int main(void)
{
    //1.创建套接字
    char tmpbuff[1024] = {"hello"};
    ssize_t nsize = 0;
    int ret = 0;
    socklen_t addrlen = sizeof(sendaddr);

    recvaddr.sin_family = AF_INET;
    recvaddr.sin_port = htons(RECV_PORT);
    recvaddr.sin_addr.s_addr = inet_addr(RECV_IP);

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (-1 == sockfd)
    {
        perror("fail to socket");
        return -1;
    }

    ret = bind(sockfd, (struct sockaddr *)&recvaddr, sizeof(recvaddr));
    if (-1 == ret)
    {
        perror("fail to bind");
        return -1;
    }

    //2.接收一次
    nsize = recvfrom(sockfd, tmpbuff, sizeof(tmpbuff), 0, (struct sockaddr *)&sendaddr, 
    if (-1 == nsize)
    {
        perror("fail to recvfrom");
        return -1;
    }

    //3.创建两个线程
    pthread_create(&tid1, NULL, thread1, NULL);
    pthread_create(&tid2, NULL, thread2, NULL);

    pthread_join(tid1, NULL);
    pthread_join(tid2, NULL);

    close(sockfd);

    return 0;
}