linux上C语言实现udp

超、凢脫俗 2022-05-26 03:59 208阅读 0赞

目的：C语言实现udp\_client 和udp\_server功能，实现简单的数据收发功能；

参考出处：

1、https://www.cnblogs.com/yuqiao/p/5786427.html //socket接口详解

2、https://blog.csdn.net/zgrjkflmkyc/article/details/8605333

文件需要包含<fcntl.h>以及<unistd.h>文件，否则编译时出现close（）函数未定义warning。

![70][]

测试UDP server：

![70 1][]

测试UDP client：

![70 2][]

/\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*client.c\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*/  
\#include<stdio.h>  
\#include<stdlib.h>  
\#include<string.h>  
\#include<sys/socket.h>  
\#include<netinet/in.h>  
\#include<arpa/inet.h>  
\#include<netdb.h>  
\#include<errno.h>  
\#include<sys/types.h>  
\#include <fcntl.h>//for open

\#include<unistd.h>//for close

int port=8888;  
  
int main(int argc,char \*argv\[\])\{  
int sockfd;  
int i=0;  
int z;  
char buf\[80\],str1\[80\];  
struct hostent \*host;  
struct sockaddr\_in adr\_srvr;  
if(argc<2)\{  
fprintf(stderr,"please enter the server's hostname!\\n");  
exit(1);  
\}  
if((host=gethostbyname(argv\[1\]))==NULL)\{  
herror("gethostbyname error!");  
exit(1);  
\}  
FILE \*fp;  
printf("open file....\\n");  
fp=fopen("liu","r");  
if(fp==NULL)\{  
perror("failed to open file");  
exit(1);  
\}  
printf("connecting server....\\n");  
adr\_srvr.sin\_family=AF\_INET;  
adr\_srvr.sin\_port=htons(port);  
adr\_srvr.sin\_addr=\*((struct in\_addr \*)host->h\_addr);  
bzero(&(adr\_srvr.sin\_zero),8);  
sockfd=socket(AF\_INET,SOCK\_DGRAM,0);  
// printf("socket %d\\r\\n",sockfd);  
if(sockfd==-1)\{  
perror("socket error!");  
exit(1);  
\}  
printf("send file ...\\n");  
for(i=0;i<3;i++)\{  
fgets(str1,80,fp);  
printf("%d:%s",i,str1);  
sprintf(buf,"%d:%s",i,str1);  
z=sendto(sockfd,buf,strlen(buf),0,(struct sockaddr \*)&adr\_srvr,sizeof(adr\_srvr));  
if(z<0)\{  
perror("recvfrom error");  
exit(1);  
\}  
\}  
sprintf(buf,"stop\\n");  
z=sendto(sockfd,buf,strlen(buf),0,(struct sockaddr \*)&adr\_srvr,sizeof(adr\_srvr));  
printf("send over.\\n");  
if(z<0)\{  
perror("sendto error");  
exit(1);  
\}  
fclose(fp);  
close(sockfd);  
exit(0);

/\*\*\*\*\*\*\*\*\*\*\*\*\*\*server.c\*\*\*\*\*\*\*\*\*\*\*\*\*\*/  
\#include<stdio.h>  
\#include<stdlib.h>  
\#include<string.h>  
\#include<sys/socket.h>  
\#include<netinet/in.h>  
\#include<arpa/inet.h>  
\#include<netdb.h>  
\#include<errno.h>  
\#include<sys/types.h>  
\#include<fcntl.h>//for open  
\#include<unistd.h> //for close  
  
  
int port=8888;  
int main()\{  
int sockfd;  
int len;  
int z;  
char buf\[256\];  
struct sockaddr\_in adr\_inet;  
struct sockaddr\_in adr\_clnt;  
printf("waiting for client...\\n");  
  
sockfd=socket(AF\_INET,SOCK\_DGRAM,0);  
if(sockfd==-1)\{  
perror("socket error\_1");  
exit(1);  
\}  
printf("start bind..\\n");  
adr\_inet.sin\_family=AF\_INET;  
adr\_inet.sin\_port=htons(port);  
adr\_inet.sin\_addr.s\_addr=htonl(INADDR\_ANY);  
printf("bind para ok\\n");  
bzero(&(adr\_inet.sin\_zero),8);  
len=sizeof(adr\_clnt);  
z=bind(sockfd,(struct sockaddr \*)&adr\_inet,sizeof(adr\_inet));  
if(z==-1)\{  
perror("bind error\_1");  
\}else\{  
printf("bind ok\\n");  
\}  
  
  
while(1)\{  
// printf("before rec %s,",buf);  
z=recvfrom(sockfd,buf,sizeof(buf),0,(struct sockaddr \*)&adr\_clnt, &len);  
 printf("rx data\_len: %d \\n", z);  
if(z<0)\{  
perror("recvfrom error\_1");  
exit(1);  
\}  
buf\[z\]=0;  
printf("接收：%s\\n",buf);  
if(strncmp(buf,"stop",4)==0)\{  
printf("结束....\\n");  
break;  
\}  
\}  
close(sockfd);  
exit(0);  
\}

[70]: /images/20220526/ad116a3c9547418a859a6f3d172b091c.png
[70 1]: /images/20220526/d4243fda11b645288f4084a48c149f65.png
[70 2]: /images/20220526/c49b78cff6f44148956ecac1e4aa17b4.png