十九、UDP编程和IO多路复用

news2025/5/28 1:15:19

1、UDP编程

服务端：
#include<stdio.h>
#include <arpa/inet.h>
#include<stdlib.h>
#include<string.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <pthread.h>
#include <strings.h>
#define QUIT_STR "QUIT"
#define SERV_PORT 5001
#define SERV_IP_ADDR "192.168.238.128" 
#define bufsize 1024
        
int main()
{
	int fd =-1;
	//1.socket
	fd = socket(AF_INET,SOCK_DGRAM,0);
	if(fd ==-1)
	{
		perror("socket\n");
		exit(1);
	}
	//2.addr
	int b_reuser=1;
	setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&b_reuser,sizeof(int));
	//3.bind
	struct sockaddr_in sin;
	bzero(&sin,sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_port = htons(SERV_PORT);
	sin.sin_addr.s_addr = htonl(INADDR_ANY);
        if(bind(fd,(struct sockaddr*)&sin,sizeof(sin))<0)
	{
		perror("bind");
		exit(1);
	}	
	char buf[bufsize];
	//4.recvfrom
	struct sockaddr_in cin;
	socklen_t addrlen=sizeof(cin);
	while(1)
	{
	bzero(buf,bufsize);
        if(recvfrom(fd,buf,bufsize-1,0,(struct sockaddr*)&cin,&addrlen)<0)
	{
		perror("recvfrom\n");
		continue;
	}
	char ipv4_addr[16];
	if(!inet_ntop(AF_INET,(void*)&cin.sin_addr,ipv4_addr,sizeof(cin)))
	{
		perror("inet_ntop");
		exit(1);
	}
	printf("recvive from (%s,%d),data:%s\n",ipv4_addr,ntohs(cin.sin_port),buf);
	if(!strncasecmp(buf,QUIT_STR,strlen(QUIT_STR)))
	{
		printf("cilent:(%s,%d)\n",ipv4_addr,ntohs(cin.sin_port));
	}

	}
	close(fd);
	return 0;
}

客户端
#include<stdio.h>
#include <arpa/inet.h>
#include<stdlib.h>
#include<string.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <pthread.h>
#include <strings.h>
#define QUIT_STR "QUIT"
#define SERV_PORT 5001
#define SERV_IP_ADDR "192.168.238.128" 
#define bufsize 1024
        
int main(int argc,char** argv)
{
	if(argc!=3)
	{
		exit(1);
	}
	int port=-1;
	port=atoi(argv[2]);
	int fd =-1;
	//1.socket
	fd = socket(AF_INET,SOCK_DGRAM,0);
	if(fd ==-1)
	{
		perror("socket\n");
		exit(1);
	}
	struct sockaddr_in sin;
	bzero(&sin,sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_port = htons(port);
	sin.sin_addr.s_addr = inet_addr(argv[1]);
        
	char buf[bufsize];
	//send
	while(1)
	{
		bzero(buf,bufsize);
		if(fgets(buf,bufsize-1,stdin) == NULL)
                          {
			        perror("fgets");
                                continue;
			  }
                sendto(fd,buf,bufsize-1,0,(struct sockaddr*)&sin,sizeof(sin));
		if(!strncasecmp(buf,QUIT_STR,strlen(QUIT_STR)))
				{
				perror("strncasecmp");
				exit(1);
				}
	}
	close(fd);
	return 0;
}

运行结果：

2、IO多路复用

服务端：
#include<stdio.h>
#include <arpa/inet.h>
#include<stdlib.h>
#include<string.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <pthread.h>
#include <strings.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <unistd.h>
#define QUIT_STR "QUIT"
#define SERV_RESP_STR "SERVER:"
#define SERV_IP 5001
#define SERV_IP_ADDR "192.168.238.128" 
#define bufsize 1024
void child_data_handle(int signum)
{
	if(SIGCHLD==signum)
	{
		waitpid(-1,NULL,WNOHANG);
	}
}
void* cilent_data_handle(void* arg)
{
	int newfd=*(int *)arg;
	char respbuf[bufsize];
  char buf[bufsize];
  printf("child process handle:newfd = %d\n",newfd);
        int ret =-1;
        while(1)
        {
                do
                {
                        bzero(buf,bufsize);
                        ret=read(newfd,buf,bufsize-1);
                }while(ret<1);
                if(ret<0)
                {
                        exit(1);
                }
                if(!ret)
                {
                   break;
                }
                printf("recive data is %s\n",buf);
		bzero(respbuf,bufsize-1);
		strncpy(respbuf,SERV_RESP_STR,strlen(SERV_RESP_STR));
		strcat(respbuf,buf);
                 do
		 {
			 ret =write(newfd,respbuf,strlen(respbuf));
		 }while(ret<0);



                if(!strncasecmp(buf,QUIT_STR,strlen(QUIT_STR)))
                                {
                                    printf("cilenr is exiting!\n");
                                    break;
                                    }
        }
        close(newfd);


}
int main()
{
	int fd=-1;
	signal(SIGCHLD,child_data_handle);
	fd=socket(AF_INET,SOCK_STREAM,0);
	if(fd == -1)
	{
		perror("socket");
			exit(1);
	}
	struct sockaddr_in sin;
	bzero(&sin,sizeof(sin));
	sin.sin_family=AF_INET;
	sin.sin_port = htons(SERV_IP);
	sin.sin_addr.s_addr = INADDR_ANY;
/*	if(inet_pton(AF_INET,SERV_IP_ADDR,(void*)&sin.sin_addr.s_addr)!=1)
	{
		perror("inet_pton");
		exit(1);
	}
	*/
	//2.bind
        if(bind(fd,(struct sockaddr *)&sin,sizeof(sin))<0)
	{
	   perror("bind");
	   exit(1);	   
	}
	//3.listen
	if(listen(fd,5)<0)
	{
		perror("listen");
		exit(1);
	}
	//4.accep
         int newfd=-1;
	 pthread_t tid;
	 pid_t pid;
	 struct sockaddr_in cin;
	 socklen_t addrlen=sizeof(cin);
	 while(1)
        {

	newfd= accept(fd,(struct sockaddr*)&cin,&addrlen);
	if(newfd<0)
	{
		perror("accept");
		exit(1);
	}
        pid = fork();
	if(pid<0)
	{
		perror("fork");
		break;
	}
	if(pid == 0)
	{
	char IPV4_addr[16];
	if(!inet_ntop(AF_INET,(void *)&cin.sin_addr,IPV4_addr,sizeof(cin)))
	{
		perror("inet_ntop");
		exit(1);
	}
	printf("cilent:(%s,%d)is connect\n",IPV4_addr,ntohs(cin.sin_port));
	cilent_data_handle(&newfd);
        close(fd);
	}
	if(pid >0)
	{
	   close(newfd);
	}
	}
	//read


	return 0;
}

客户端：
#include<stdio.h>
#include <arpa/inet.h>
#include<stdlib.h>
#include<string.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <pthread.h>
#include <strings.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#define SERV_RESP_STR "SERVER:"
#define QUIT_STR "QUIT"
#define SERV_PORT 5001
#define SERV_IP_ADDR "192.168.238.128" 
#define bufsize 1024
        
int main(int argc,char** argv)
{
	if(argc!=3)
	{
		exit(1);
	}
	int port=-1;
	port=atoi(argv[2]);
	int fd =-1;
	//1.socket
	fd = socket(AF_INET,SOCK_STREAM,0);
	if(fd ==-1)
	{
		perror("socket\n");
		exit(1);
	}
	struct sockaddr_in sin;
	bzero(&sin,sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_port = htons(port);
	sin.sin_addr.s_addr = inet_addr(argv[1]);
	if(connect(fd,(struct sockaddr*)&sin,sizeof(sin))<0)
	{
		perror("connect");
		exit(1);
	}
	fd_set rset;
	int maxfd =-1;
	char buf[bufsize];
	int ret =-1;
	struct timeval tout;
	while(1)
	{
		FD_ZERO(&rset);
		FD_SET(0,&rset);
		FD_SET(fd,&rset);
		maxfd = fd;
		tout.tv_sec = 5;
		tout.tv_usec = 0;
		select(maxfd+1,&rset,NULL,NULL,&tout);
		if(FD_ISSET(0,&rset))
		{
			bzero(buf,bufsize);
			do
			{
			ret = read(0,buf,bufsize-1);
			}while(ret<0);
			if(ret<0)
			{
				perror("read");
				continue;
			}
			if(!ret)
			{
		            continue;
		        }
			if(write(fd,buf,strlen(buf))<0)
			{
				perror("write");
				continue;
			}
			 if(!strncasecmp(buf,QUIT_STR,strlen(QUIT_STR)))
                                {
                                printf("cilent is exited!\n");
                                break;
                                }

		}
		if(FD_ISSET(fd,&rset))
		{
			 bzero(buf,bufsize);
                        do
                        {
                        ret = read(fd,buf,bufsize-1);
                        }while(ret<0);
                        if(ret<0)
                        {
                                perror("read");
                                continue;
                        }
                        if(!ret)
                        {
                            break;
                        }
                        printf("service said:%s\n",buf);
                         if((strlen(buf)>strlen(SERV_RESP_STR))    &&     (!strncasecmp(buf,QUIT_STR,strlen(QUIT_STR))))
                                {
                                printf("cilent is exited!\n");
                                break;
                                }


		}
	}
        
/*	char buf[bufsize];
	//send
	while(1)
	{
		bzero(buf,bufsize);
		if(fgets(buf,bufsize-1,stdin) == NULL)
                          {
			        perror("fgets");
                                continue;
			  }
                sendto(fd,buf,bufsize-1,0,(struct sockaddr*)&sin,sizeof(sin));
		if(!strncasecmp(buf,QUIT_STR,strlen(QUIT_STR)))
				{
				perror("strncasecmp");
				exit(1);
				}
	}*/
	close(fd);
	return 0;
}

运行结果：