UDP回射

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <fcntl.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <errno.h>

#define SERV_PORT 33901
#define BUFFSIZE 1024
void dg_echo(int sockfd,struct sockaddr*pcliaddr,socklen_t clilen);

int main(int ac,char**av)
{
    int sockfd;
    struct sockaddr_in servaddr,clientaddr;
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd<0){
	perror("socket");
	exit(0);
    }
    servaddr.sin_family=AF_INET;
    servaddr.sin_port=htons(SERV_PORT);
    servaddr.sin_addr.s_addr=htonl(INADDR_ANY);

    bind(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
    dg_echo(sockfd,(struct sockaddr*)&clientaddr,sizeof(clientaddr));
    return 0;
}
void dg_echo(int sockfd,struct sockaddr* pcliaddr,socklen_t clilen)
{
    int n;
    socklen_t len;
    while(1){
	char mesg[BUFFSIZE];
	bzero(mesg,sizeof(mesg));
	len=clilen;
	n=recvfrom(sockfd,mesg,BUFFSIZE,0,pcliaddr,&len);
	if(n<0){
	    perror("recvfrom");
	    continue;
	}
	char servermsg[BUFFSIZE]="From server:";
	int l=strlen(servermsg);
	servermsg[l]=0;
	strcat(servermsg,mesg);
	sendto(sockfd,servermsg,n+l,0,pcliaddr,len);
    }
}








#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <fcntl.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <errno.h>

#define SERV_PORT 33901
#define BUFFSIZE 1024
void dg_client(FILE*fp,int sockfd,const struct sockaddr*pserver,
	socklen_t servlen);
int main(int ac,char**av)
{
    int sockfd;
    struct sockaddr_in servaddr;
    socklen_t servlen=sizeof(servaddr);
    bzero(&servaddr,sizeof(servaddr));
    servaddr.sin_family=AF_INET;
    servaddr.sin_port=htons(SERV_PORT);
    inet_pton(AF_INET,av[1],&servaddr.sin_addr);
    sockfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sockfd<0){
	perror("socket");
	exit(0);
    }
    dg_client(stdin,sockfd,(struct sockaddr*)&servaddr,servlen);
    return 0;
}
void dg_client(FILE*fp,int sockfd,const struct sockaddr*pserver,
	socklen_t servlen)
{
    int n;
    char sendline[BUFFSIZE],recvline[BUFFSIZE+1];
    printf("From client:");
    while(fgets(sendline,BUFFSIZE,fp)!=NULL){
	sendto(sockfd,sendline,strlen(sendline),0,
		pserver,servlen);
	n=recvfrom(sockfd,recvline,BUFFSIZE,0,NULL,NULL);
	if(n<0){
	    perror("recvfrom");
	    exit(0);
	}
	recvline[n]=0;
	fputs(recvline,stdout);
	printf("From client:");
    }
}



obj=cl
all:
	gcc $(obj).c -o $(obj)
clear:
	rm -rf $(obj) $(obj).o


obj=se
all:
	gcc $(obj).c -o $(obj)
clear:
	rm -rf $(obj) $(obj).o