网络编程TCP和UDP

本文主要是介绍网络编程TCP和UDP，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

将TCP的CS模型再敲一遍

TCP服务器

1->创建原始的套接字描述符

2->将原始套接字与主机ip绑定

3->将原始套接字设置监听状态

4->接收客户端连接，获取客户端信息，因为原始套接字被用了，所以创建新的套接字描述符用于客户端通信

5->发送接收信息

6->关闭

#include <myhead.h>#define SERPORT 3456
#define SERIP "192.168.0.102"
#define BACKLOG 5
int main(int argc, const char *argv[])
{int oldfd = socket(AF_INET,SOCK_STREAM,0);if(oldfd == -1){perror("socket");return -1;}printf("旧的套接字创建成功\n");//2.绑定主机的IP和端口号struct sockaddr_in sin = {.sin_family = AF_INET,//使用IPv4通信协议族.sin_port = htons(SERPORT),//设置端口号.sin_addr.s_addr = inet_addr(SERIP)//设置IP地址为本机地址};//定义服务器地址结构体变量if(bind(oldfd,(struct sockaddr *)&sin,sizeof(sin)) == -1)//绑定ip{perror("bind");return -1;}printf("绑定成功\n");if(listen(oldfd,BACKLOG) == -1)//监听客户端需求{perror("listen");return -1;}printf("监听成功\n");char buff[1024];struct sockaddr_in cin;//定义获取客户端信息结构体socklen_t cinlen = sizeof(cin);//获取结构体大小int newfd = accept(oldfd,(struct sockaddr *)&cin,&cinlen);//接收请求，创建新的描述符if(newfd == -1){perror("accept");return -1;}printf("%s:%d客户端发来连接请求\n",inet_ntoa(cin.sin_addr),ntohs(cin.sin_port));while(1){memset(buff,0,sizeof(buff));//int len = read(newfd,buff,sizeof(buff));int len = recv(newfd,buff,sizeof(buff),0);printf("读取的信息:%s\n",buff);if(len == 0){printf("你客户跑了\n");}strcat(buff,"520");//write(newfd,buff,sizeof(buff));send(newfd,buff,sizeof(buff),0);memset(buff,0,sizeof(buff));}close(oldfd);close(newfd);return 0;
}

TCP客户端

1->创建原始套接字描述符

2->可以绑定也可以不绑定，这里就没有绑定了

3->连接服务器，创建结构体用于接收自己的信息，在连接时要带上自己“身份”

4->发送接收信息

5->关闭

#include <myhead.h>#define SERPORT 3456
#define SERIP "192.168.0.102"
int main(int argc, const char *argv[])
{int oldfd = socket(AF_INET,SOCK_STREAM,0);if(oldfd == -1){perror("socket");return -1;}//2.绑定(可选)//连接服务器struct sockaddr_in cin = {.sin_family = AF_INET,//使用IPv4通信协议族.sin_port = htons(SERPORT),//设置端口号.sin_addr.s_addr = inet_addr(SERIP)//设置IP地址为本机地址};//定义服务器地址结构体变量if(connect(oldfd,(struct sockaddr *)&cin,sizeof(cin)) == -1){perror("connect");return -1;}printf("连接成功\n");char buff[1024];while(1){memset(buff,0,sizeof(buff));printf("客户端发信息");fgets(buff,sizeof(buff),stdin);buff[strlen(buff)-1] = '\0';send(oldfd,buff,sizeof(buff),0);recv(oldfd,buff,sizeof(buff),0);printf("收到服务器信息%s\n",buff);}close(oldfd);return 0;
}

UDP服务器中，使用connect函数，实现唯一的客户端与服务器通话

UDP服务器

UDP服务器可以不连接（connect），连接后会与指定的客户端通信，不会接收其他客户端信息

代码中当接收到ccc字符串的时候使用connect函数，就只与发ccc字符串的客户端通信了

#include <myhead.h>#define SERPORT 8888
#define SERIP "192.168.0.102"
int main(int argc, const char *argv[])
{int oldfd = socket(AF_INET,SOCK_DGRAM,0);if(-1 == oldfd){perror("socket");return -1;}struct sockaddr_in sin = {.sin_family = AF_INET,.sin_port = htons(SERPORT),.sin_addr.s_addr = inet_addr(SERIP)};if(bind(oldfd,(struct sockaddr*)&sin,sizeof(sin)) == -1){perror("bind");return -1;}struct sockaddr_in cin;socklen_t cinlen = sizeof(cin);char buff[100];while(1){memset(buff,0,sizeof(buff));int len = recvfrom(oldfd,buff,sizeof(buff),0,(struct sockaddr*)&cin,&cinlen);if(strcmp(buff,"ccc")==0){connect(oldfd,(struct sockaddr*)&cin,cinlen);}if(len == 0){printf("客户端跑了\n");break;}printf("服务器接收到信息:%s\n",buff);//strcat(buff,"666");//sendto(oldfd,buff,sizeof(buff),0,(struct sockaddr*)&sin,sizeof(sin));//printf("发送成功\n");//memset(buff,0,sizeof(buff));}close(oldfd);return 0;
}

UDP客户端

#include <myhead.h>#define CLIPORT 8888
#define CLIIP "192.168.0.102"
int main(int argc, const char *argv[])
{int oldfd = socket(AF_INET,SOCK_DGRAM,0);if(oldfd == -1){perror("socket");return -1;}struct sockaddr_in cin = {.sin_family = AF_INET,.sin_port = htons(CLIPORT),.sin_addr.s_addr = inet_addr(CLIIP)};char buff[1024];while(1){printf("客户端发信息：");fgets(buff,sizeof(buff),stdin);sendto(oldfd,buff,sizeof(buff),0,(struct sockaddr*)&cin,sizeof(cin));printf("发送成功");}close(oldfd);return 0;
}

TCP和UDP的思维导图

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