网络编程基础

TCP服务端

#include <myhead.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define ERR_MSG(msg) do{\
    fprintf(stderr,"__%d__:",__LINE__);\
    perror(msg);\
}while(0)

#define PORT 8888      //端口号，范围1024～49151
#define IP "192.168.114.5"
int main(int argc, const char *argv[])
{

	//创建流式套接字
	int sfd=socket(AF_INET,SOCK_STREAM,0);
		if(sfd<0)
		{
			ERR_MSG("socket");
			return -1;
    	}
	printf("socket create success sfd=%d\n",sfd);
    //允许端口快速的被复用
    int reuse = 1;                                                            
    if(setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0)
    {
        ERR_MSG("setsockopt");
        return -1;
	}
	printf("允许端口快速的被复用成功\n");

	//填充地址信息结构体给BIND函数绑定，
	//真实的地址信息结构体根据地址族指定 AF_INET:man 7 ip
	struct sockaddr_in sin;
	sin.sin_family       =AF_INET;
	sin.sin_port         =htons(PORT);
	sin.sin_addr.s_addr=inet_addr(IP);

	//绑定服务器到地址信息  --->必须绑定bind 
	if(bind(sfd,(struct sockaddr*)&sin,sizeof(sin))<0)
	{
		ERR_MSG("bind");
		return -1;
	}
	printf("bind success\n");

	//将套接字设置为被动监听状态听 listen
	if(listen(sfd,128)<0)
	{
		ERR_MSG("listen");
		return -1;
	}
	printf("listen success\n");

	//获取一个已经完成的客户端信息，生成一个新的文件描述符符
	int newfd=-1;
	struct sockaddr_in cin;
	socklen_t addrlen=sizeof(cin);

	//accept(sfd,NULL,NULL);
	newfd=accept(sfd,(struct sockaddr*)&cin,&addrlen);
	if(newfd<0)
	{
		ERR_MSG("newfd");
		return -1;
	}
	printf("[%s:%d]客户端连接成功 newfd=%d\n",inet_ntoa(cin.sin_addr),ntohs(cin.sin_port),newfd);
	char buf[128]="";
	ssize_t res=0;
	while(1)
	{
		//清空字符串
		bzero(buf,sizeof(buf));

		//接收
	    res=recv(newfd,buf,sizeof(buf),0);
		if(res<0)
		{
			ERR_MSG("recv");
			return -1;
		}
		else if(0 == res)
		{
			printf("[%s:%d]客户端下线 newfd=%d\n",\
					inet_ntoa(cin.sin_addr),\
					ntohs(cin.sin_port),newfd);
			break;
		}
		printf("[%s:%d]客户端连接成功 newfd=%d : %s\n",inet_ntoa(cin.sin_addr),ntohs(cin.sin_port),newfd,buf);

		//发送
		strcat(buf,"*_*");
		if(send(newfd,buf,sizeof(buf),0)<0)
		{
			ERR_MSG("send");
			return -1;
		}
		printf("send success\n");
		
		
	}
	//关闭文件描述符
	close(newfd);
	if(close(sfd)<0)
	{
		ERR_MSG("close");
		return -1;
	}


	return 0;
}

，TCP客户端

#include <myhead.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define ERR_MSG(msg) do{\
    fprintf(stderr,"__%d__:",__LINE__);\
    perror(msg);\
}while(0)

#define PORT 8888      //端口号，范围1024～49151
#define IP "192.168.114.5"
int main(int argc, const char *argv[])
{

	//创建流式套接字
	int cfd=socket(AF_INET,SOCK_STREAM,0);
		if(cfd<0)
		{
			ERR_MSG("socket");
			return -1;
    	}
	printf("socket create success cfd=%d\n",cfd);
    //允许端口快速的被复用
    int reuse = 1;                                                            
    if(setsockopt(cfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0)
    {
        ERR_MSG("setsockopt");
        return -1;
	}
	printf("允许端口快速的被复用成功\n");

	//填充服务器地址信息结构体给connect函数绑定，
	//想连哪个服务器，就填哪个服务器绑定
	//真实的地址信息结构体根据地址族指定 AF_INET:man 7 ip
	struct sockaddr_in sin;
	sin.sin_family       =AF_INET;
	sin.sin_port         =htons(PORT);
	sin.sin_addr.s_addr=inet_addr(IP);

	if(connect(cfd,(struct sockaddr*)&sin,sizeof(sin))<0)
	{
		ERR_MSG("conect");
		return -1;
	}
	printf("connect success\n");

    char buf[128]="";
	ssize_t res=0;
	while(1)
	{
		//清空字符串
		bzero(buf,sizeof(buf));
        printf("请输入>>>");
		fgets(buf,sizeof(buf),stdin);
		buf[strlen(buf)-1]=0;
		//发送

		if(send(cfd,buf,sizeof(buf),0)<0)
		{
			ERR_MSG("send");
			return -1;
		}
		printf("send success\n");
		

		//接收
	    res=recv(cfd,buf,sizeof(buf),0);
		if(res<0)
		{
			ERR_MSG("recv");
			return -1;
		}
		else if(0 == res)
		{
			printf("服务端下线 cfd=%d\n",cfd);
			break;
		}
		printf("cfd=%d : %s\n",cfd,buf);

		//发送
		strcat(buf,"*_*");
		if(send(cfd,buf,sizeof(buf),0)<0)
		{
			ERR_MSG("send");
			return -1;
		}
		printf("send success\n");
		
		
	}
	//关闭文件描述符
	close(cfd);
	if(close(cfd)<0)
	{
		ERR_MSG("close");
		return -1;
	}


	return 0;
}

 

 UDP服务端

#include <myhead.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define ERR_MSG(msg) do{\
    fprintf(stderr,"__%d__:",__LINE__);\
    perror(msg);\
}while(0)


#define PORT 8888      //端口号，范围1024～49151
#define IP "192.168.114.5"


int main(int argc, const char *argv[])
{
//创建报式套接字 socket
    int sfd = socket(AF_INET, SOCK_DGRAM, 0);
    if(sfd < 0)                                                                       
    {
        ERR_MSG("socket");
        return -1;
    }
    printf("socket create success sfd=%d\n", sfd);

    //填充服务器的地址信息结构体，给bind函数使用
    //真实的地址信息结构体根据地址族指定，AF_INET:man 7 IP
    struct sockaddr_in sin;
    sin.sin_family      = AF_INET;      //必须填AF_INET;
    sin.sin_port        = htons(PORT);  //端口号的网络字节序，1024-49151
    sin.sin_addr.s_addr = inet_addr(IP);//本机IP, ifconfig

    //绑定地址信息结构体--->bind
    if(bind(sfd, (struct sockaddr*)&sin, sizeof(sin)) < 0)
    {
        ERR_MSG("bind");
        return -1;
    }
    printf("bind success\n");

    char buf[128] = "";
    struct sockaddr_in cin;     //存储发送方的地址信息;
    socklen_t addrlen = sizeof(cin);

    while(1)
    {
        bzero(buf, sizeof(buf));
        //接收数据
        /*
        //在不考虑sendto回复信息的情况下可以使用
        //if(recvfrom(sfd, buf, sizeof(buf), 0, NULL, NULL) < 0)
        //if(recv(sfd, buf, sizeof(buf), 0) < 0)
        //if(read(sfd, buf, sizeof(buf)) < 0)
        */

        if(recvfrom(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&cin, &addrlen) < 0)
        {
            ERR_MSG("recv");
            return -1;
        }
        printf("[%s:%d] : %s\n", inet_ntoa(cin.sin_addr), ntohs(cin.sin_port), buf);

        //发送数据----->谁发给我，我发还给谁
        strcat(buf, "*_*");
        if(sendto(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&cin, sizeof(cin)) < 0)
        {
            ERR_MSG("sendto");
            return -1;
        }
        printf("sendto success\n");
    }


    //关闭套接字
    close(sfd);
	return 0;
}