Linux UDP EchoServer守护进程编写
平时工作中主要用java,不过还是对Linux非常喜爱,虽然学习时间有限,每天还是能学点小东西,呵呵,写了一个HelloWorld版的Linux守护进程,启动后监听UDP端口做简单的echo back
Server代码
#include<sys/socket.h>#include<netinet/in.h>#include<strings.h>#include<stdio.h>#include<syslog.h>#include<stdlib.h>#include<signal.h>#include <sys/types.h> /* basic system data types */#include <sys/socket.h> /* basic socket definitions */#include <sys/time.h> /* timeval{} for select() */#include <time.h> /* timespec{} for pselect() */#include <netinet/in.h> /* sockaddr_in{} and other Internet defns */#include <arpa/inet.h> /* inet(3) functions */#include <errno.h>#include <fcntl.h> /* for nonblocking */#include <netdb.h>#include <signal.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/stat.h> /* for S_xxx file mode constants */#include <sys/uio.h> /* for iovec{} and readv/writev */#include <unistd.h>#include <sys/wait.h>#include <sys/un.h> /* for Unix domain sockets */int init_deamon(){ pid_t pid; if((pid=fork())<0){ return (-1); }else if(pid){ exit(0); } if(setsid()<0){ return (-1); } signal(SIGHUP,SIG_IGN); if((pid=fork())<0){ return (-1); }else if(pid){ exit(0); } chdir("/"); int i=0; for(;i<64;i++){ close(i); } open("/dev/null",O_RDONLY); open("/dev/null",O_RDWR); open("/dev/null",O_RDWR); openlog("deamon server start for udp",LOG_PID,0); syslog(LOG_INFO|LOG_LOCAL2,"Yep,That's me"); return (0);}void dg_echo(int sockfd,struct sockaddr *cliaddr,socklen_t clilen){ int n; socklen_t len; char str[16]; char msg[1024]; for(;;){ len=clilen; n=recvfrom(sockfd,msg,1024,0,cliaddr,&clilen); printf("recv from %s \n",inet_ntop(AF_INET,&cliaddr,str,sizeof(str))); sendto(sockfd,msg,n,0,cliaddr,clilen); msg[n]=0; fputs(msg,stdout); syslog(LOG_INFO|LOG_LOCAL2,msg); }}int main(int argc,char **argv){ int sockfd; struct sockaddr_in servaddr,cliaddr; init_deamon(); sockfd=socket(AF_INET,SOCK_DGRAM,0); bzero(&servaddr,sizeof(servaddr)); servaddr.sin_family=AF_INET; servaddr.sin_addr.s_addr=htonl(INADDR_ANY); servaddr.sin_port=htons(22111); bind(sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr)); dg_echo(sockfd,(struct sockaddr *)&cliaddr,sizeof(cliaddr));}#include<stdio.h>#include<stdlib.h>#include<sys/socket.h>#include<netinet/in.h>#include<strings.h>void dg_cli(FILE *fp,int sockfd,struct sockaddr *servaddr,socklen_t servlen){ int n; socklen_t len; struct sockaddr *replyaddr; replyaddr=malloc(servlen); char readline[1024],sendline[1025]; char str[16]; connect(sockfd,servaddr,servlen); while(fgets(sendline,1024,fp)!=NULL){ write(sockfd,sendline,strlen(sendline)); n=read(sockfd,readline,1024); // if(len!=servlen||memcmp(servaddr,replyaddr,len)!=0){ // printf("reply from %s (ignored)\n",inet_ntop(AF_INET,&replyaddr,str,sizeof(str))); // continue; // } readline[n]=0; fputs(readline,stdout); }}int main(int argc,char **argv){ int sockfd; struct sockaddr_in servaddr; if(argc!=2){ printf("usage:udpcli <IPAddress>\n"); exit(1); } bzero(&servaddr,sizeof(servaddr)); servaddr.sin_family=AF_INET; servaddr.sin_port=htons(22111); inet_pton(AF_INET,argv[1],&servaddr.sin_addr); sockfd=socket(AF_INET,SOCK_DGRAM,0); dg_cli(stdin,sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr)); exit(0);}