客户端程序源代码.doc

#include #include #include #include #include #define rec_length20main(int argc, char *argv )/structure defined for request as a clientstructhostent *hp1;structsockaddr_in sin1;structservent *sp1;charsbuf50;intss,spid;char*sservice,*sdest;/structure defined for request as a serverstruct sockaddr_in sin;struct servent *sp;int s,ns,pid;charbuf50;char*service;/test the environment parameter: lservice, dservice, server_nameif(argc=4) service=argv1;sservice=argv2; sdest=argv3;else fprintf(stderr,Parameter assigned Error!nUsage:n);fprintf(stderr,t%s lservice dservice server_name!n,argv0);fprintf(stderr,Note: server_name is defined in file /etc/hostsn);fprintf(stderr,and: lservice dservice are defined in file /etc/servicesn);exit(-1);if(sp=getservbyname(service,tcp)=NULL)fprintf(stderr,Error: getservbyname);exit(-5);if(s=socket(AF_INET,SOCK_STREAM,0)=-1)fprintf(stderr,Error: socket create);exit(-6);bzero(&sin,sizeof(sin);sin.sin_port=sp-s_port;if(bind(s,&sin,sizeof(sin)=-1)fprintf(stderr,Error: bind);close(s); exit(-6);if(listen(s,5)=-1)fprintf(stderr,Error: listen);close(s); exit(-6);while(1) fprintf(stderr,nttt Now wait connect .n);if(ns=accept(s,0,0)=-1) / wait a connection */fprintf(stderr,error: accept); continue;if(pid=fork()=-1) / conneted, and then create child procfprintf(stderr,server: fork error!);close(s); exit(-1);if(pid!=0) /parent proce, nothing to do, and to the next loopclose(ns);wait(0);continue;if(pid=0) / entered child proccedureclose(s);printf(Receive a client connect:%sn,argv1);if(read(ns,buf,rec_length)=0)fprintf(stderr,Read nothing from socket:nsn);close(ns); exit(-3); printf(%s get message from ns: %sn,argv0,buf);/ request message got from the Client./ Begine a Connection to Server as a Clientif(sp1=getservbyname(sservice,tcp)=NULL)fprintf(stderr,Error: getservbyname s1);exit(-5);if(hp1=gethostbyname(sdest)=0)fprintf(stderr,Error: gethostbyname s1);exit(-6);bzero(&sin1,sizeof(sin1);bcopy(hp1-h_addr,&sin1.sin_addr,hp1-h_length);sin1.sin_family=hp1-h_addrtype;sin1.sin_port=sp1-s_port;if(ss=socket(AF_INET,SOCK_STREAM,0)=-1)fprintf(stderr,Error: socket s1);exit(-6);if(connect(ss,&sin1,sizeof(sin1)=-1)fprintf(stderr,Error: connect s1);close(ss); exit(-6);/ next 2 Line build request messagespid=getpid();sprintf(sbuf,%5.5d%5.5d%5.5d%5.5d,spid,spid*2,spid*3,spid*4);fprintf(stderr,%s is sending request message: %s s1n,argv0,sbuf);if(write(ss,sbuf,rec_length)!=rec_length) /to server fprintf(stderr,Write Socket ss ERROR! s1n); close(ss); exit(-1); if(read(ss,sbuf,rec_length)=0)/from server fprintf(stderr,Read Socket ss Error! s1n); close(ss); exit(-2); printf(%s get reply: %sn,argv0,sbuf);close(ss);/ End the Communication with my Server/ Next 2 Line, build a replay Message buf, and write it back pid=getpid(); sprintf(buf,%5.5d%5.5d%5.5d%5.5d,pid,pid*2,pid*3,pid*4); fprintf(stderr, and, send i