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：

        应用层          发送的数据内容
        表示层          数据是否加密
        会话层          是否建立会话连接
        传输层          数据传输的方式
        网络层          数据的路由
        数据链路层      局域网内部通信
        物理层          物理介质的连接

 2.TCP/IP协议模型：

 
        应用层          发送的数据内容
        传输层          数据传输的方式
        网络层          数据由一台主机到达另一台主机
        网络接口层      物理介质连接 

 应用层  ：

            FTP     文件传输协议    
            TFTP    简单文件传输协议
            HTTP    超文本传输协议
            HTTPS   安全超文本传输协议
            SMTP    简单邮件传输协议
            TELNET  网络终端登录协议
            DNS     域名系统
            .. 

 传输层：

    TCP     传输控制协议
     UDP     用户数据报协议

            UDP：不安全、不可靠的传输方式
                 UDP机制简单
                 UDP占用的资源开销比较小
            TCP：安全、可靠的传输方式
                 TCP机制复杂
                 TCP占用的资源开销比较大 
                    三次握手建立连接,确认双方能够通信
                    通信过程中保障数据传输的完整性
                    四次挥手断开连接,确保数据传输的完整

  网络层： 
            IPV4协议
            IP地址

            管理员IP地址形式：192.168.0.167
            内存IP地址形式：  11000000.10101000.00000000.10100111

            IP地址 = 网络位 + 主机位 
            网络位：IP地址所属的网段（局域网的编号）
            主机位：局域网中的第几台主机
            网段号：网络位不变，主机位全为0 
            广播号：网络位不变, 主机位全为1 
            子网掩码：每个IP地址都会搭配一个子网掩码,用来区分IP地址的网络位及主机位
                     子网掩码展开成二进制,1对应的部分就是IP地址的网络位,0对应的部分就是IP地址的主机位
            192.168.0.167
            255.255.255.0
            11000000.10101000.00000000.10100111
            11111111.11111111.11111111.00000000

            网段号192.168.0.0
            广播号192.168.0.255

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

            A类：1.0.0.0 ~ 126.255.255.255
                子网掩码：255.0.0.0 
                管理超大规模型网络
                私有地址：10.0.0.0 ~ 10.255.255.255

            B类：128.0.0.0 ~ 191.255.255.255
                子网掩码：255.255.0.0 
                管理大中规模型网络
                私有地址：172.16.0.0 - 172.31.255.255

            C类：192.0.0.0 ~ 223.255.255.255
                子网掩码：255.255.255.0
                管理中小规模型网络
                私有地址：192.168.0.0 ~ 192.168.255.255

            D类：224.0.0.0 ~ 239.255.255.255
                用于组播：255.255.255.0

            E类：240.0.0.0 ~ 255.255.255.255
                用于实验和研究：255.255.255.0

        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

socket 
      int socket(int domain, int type, int protocol);
      功能：
        创建套接字
      参数：
        domain: AF_INET 表示IPV4协议
        type:套接字类型
            SOCK_STREAM：流式套接字
            SOCK_DGRAM:数据报套接字
            SOCK_RAW：原始套接字
        protocol:
            TCP和UDP协议：0
      返回值：  
        成功返回用来通信的文件描述符
        失败返回-1 
 

 （2）sendto 

sendto 
      ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
                      const struct sockaddr *dest_addr, socklen_t addrlen);
      功能:
        发送信息
      参数:
        sockfd:套接字文件描述符
        buf:发送数据空间首地址
        len:发送数据长度
        flags:发送属性 默认为0 
        dest_addr:目标地址存放空间首地址
        addrlen:目的地址的长度

struct sockaddr_in {
            sa_family_t    sin_family; /* address family: AF_INET */
            in_port_t      sin_port;   /* port in network byte order */
            struct in_addr sin_addr;   /* internet address */
        };

        /* Internet address. */
        struct in_addr {
            uint32_t       s_addr;     /* address in network byte order */
        };

      返回值:
        成功返回发送字节数
        失败返回-1 

  如果sendto对应的套接字没有绑定端口，则sendto绑定一个随机端口完成发送功能

（3） inet_addr

inet_addr
      in_addr_t inet_addr(const char *cp);
      功能：
        将字符串的IP地址转换为32位的地址类型

（4） htons 

htons 
      uint16_t htons(uint16_t hostshort);
      功能：    
        将本地字节序(小端)转换成网络大端字节序
 

（5） bind 

bind 
      int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
      功能：
        将套接字与IP地址和端口进行绑定
      参数:
        addr:绑定地址结构体空间首地址
        addrlen:绑定地址空间大小
      返回值：
        成功返回0 
        失败返回-1 
      注意：
        只能绑定自己的IP地址

（6）recvfrom 

 ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags,
                        struct sockaddr *src_addr, socklen_t *addrlen);
      功能：
        接收信息
      参数：
        sockfd：套接字文件描述符
        buf：接收数据空间首地址
        len：接收数据长度
        flags：接收的属性 默认为0 
        src_addr：存放发送方地址空间的地址
        addrlen: 要接收的发送方地址的长度
      返回值：
        成功返回实际接收字节数
        失败返回-1 

 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IPV4recvaddr.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,&addrlen);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, &addrlen);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;
}