客户端
 

#include <myhead.h>
#define SER_IP "192.168.125.244"
#define SER_PORT 8888
typedef struct Node
{	
	char username[20];
	struct sockaddr_in cin;
	struct Node *next;
}Node,*Node_p;
typedef struct
{
	int flag;
	char username[20];
	char data[1024];
}msg,*msg_p;
Node_p HEAD;
int SFD;
//新建客户端地址结点
Node_p create_node(Node_p head,char *username,struct sockaddr_in *cin)
{
	Node_p p=(Node_p)malloc(sizeof(Node));
	strcpy(p->username,username);
	p->cin=*cin;
	p->next=head;
	return p;
}
//插入客户端地址结点
void insert_node(Node_p head,Node_p new)
{
	new->next=head->next;
	head->next=new;
}
//删除客户端地址结点
void delete_node(Node_p head,char *username)
{
	Node_p temp=head;
	while(strcmp(temp->next->username,username))
	{
		temp=temp->next;
	}
	Node_p delete=temp->next;
	temp->next=delete->next;
	free(delete);
	delete=NULL;
}
//伪广播
void sendtoall(int sfd,Node_p head,msg_p buf,socklen_t socklen)
{
	Node_p temp=head;
	while(temp->next!=NULL)
	{
		if(sendto(sfd,buf,sizeof(msg),0,(struct sockaddr*)&temp->cin,socklen)==-1)
		{
			perror("sendto err");
			return ;
		}
		temp=temp->next;
	}
}
//服务端发送信息子线程函数
void *comm(void *arg)
{
	while(1)
	{
	msg_p commbuf=(msg_p)malloc(sizeof(msg));
	commbuf->flag=1;
	strcpy(commbuf->username,"主机");
	scanf("%s",commbuf->data);
	while(getchar()!=10);
	sendtoall(SFD,HEAD,commbuf,sizeof(commbuf));
	}
	return 0;
}
int main(int argc, const char *argv[])
{
	//创建套接字
	int sfd=socket(AF_INET,SOCK_DGRAM,0);
	if(sfd==-1)
	{
		perror("socket err");
		return -1;
	}
	//绑定主机地址
	struct sockaddr_in sin;
	sin.sin_family=AF_INET;
	sin.sin_port=htons(SER_PORT);
	sin.sin_addr.s_addr=inet_addr(SER_IP);
	if(bind(sfd,(struct sockaddr*)&sin,sizeof(sin))==-1)
	{
		perror("bind err");
		return -1;
	}
	int reuse=1;
	//设置端口重用
	if(setsockopt(sfd,SOL_SOCKET,SO_REUSEADDR,&reuse,sizeof(reuse))==-1)
	{
		perror("setsockopt err");
		return -1;
	}
	//创建客户端地址容器
	struct sockaddr_in cin;
	socklen_t socklen=sizeof(cin);
	//创建保存客户端地址的链表头结点
	Node_p head=(Node_p)malloc(sizeof(Node));
	char *host="host";
	strcpy(head->username,host);
	head->cin=sin;
	head->next=NULL;
	//创建发送信息子线程
	HEAD=head;
	SFD=sfd;
	pthread_t td;
	if(pthread_create(&td,NULL,comm,NULL))
	{
		perror("pthread_create");
		return -1;
	}
	pthread_detach(td);
	//创建消息包容器
	msg_p buf=(msg_p)malloc(sizeof(msg));
	while(1)
	{
		bzero(buf,sizeof(buf));
		recvfrom(sfd,buf,sizeof(buf),0,(struct sockaddr*)&cin,&socklen);
		switch(buf->flag)
		{
			case 0://登录
				Node_p new=create_node(head,buf->username,&cin);
				insert_node(head,new);
				sendtoall(sfd,head,buf,socklen);
				break;
			case 1://聊天
				sendtoall(sfd,head,buf,socklen);
				break;
			case 2://下线
				delete_node(head,buf->username);
				sendtoall(sfd,head,buf,socklen);
				break;
			default:
				break;
		}
	}
	free(buf);
	buf=NULL;
	return 0;
}