test12_8.txt

linux under the C programming which complementary with the book of <linux under the C programming

#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <errno.h>
#include <arpa/inet.h>
#define PROTOCOL "tcp"
#define REQUEST "GET/HTTP/1.0\n\n"

int write_buffer(int fd,const void *buf,int count);
int saferead(int fd,void *buf,size_t count);
int safewrite(int fd,void *buf,size_t count);
	
int main(int argc,char *argv[ ]){
	int sockid;
	struct servent *serviceaddr;
	struct hostent *hostaddr;
	struct protoent *protocol;
	struct sockaddr_in socketaddr;
	char buffer[1024];
	int count;

	
	bzero((char *)&socketaddr,sizeof(socketaddr));
	socketaddr.sin_family=AF_INET;
	serviceaddr=getservbyname(argv[2],PROTOCOL);
	if(!serviceaddr){
		HandleError(0, "gerservbyname", "service  resolution failed");
	}
	socketaddr.sin_port=serviceaddr->s_port;
	hostaddr=gethostbyname(argv[1]);
	if(!hostaddr){
		HandleError(0, "gethostbyname", "host resolution failed");
	}
	memcpy(&socketaddr.sin_addr,hostaddr->h_addr,hostaddr->h_length);
	protocol=getprotobyname(PROTOCOL);
	if(!protocol){
		HandleError(0, "getprotobyname", "protocol resolution failed");
	}
	sockid=socket(PF_INET,SOCK_STREAM,protocol->p_proto);
	if(sockid<0){
		HandleError(errno, "socket", "couldn’t create socket");
	}
	if(connect(sockid,&socketaddr,sizeof(socketaddr))<0){
		HandleError(errno, "connect", "connect call failed");
	}
	write_buffer(sockid,REQUEST	,strlen(REQUEST));
	while((count=saferead(sockid,buffer,sizeof(buffer)-1))){
		write_buffer(1,buffer,count);
	}
	return 0;
}

int write_buffer(int fd,const void *buf,int count){
	const void *pts=buf;
	int status=0,n;
		
	if(count<0)
		return(-1);
	while(status!=count){
		n=safewrite(fd,pts+status,count-status);
		if(n<0)
			return(n);
		status+=n;
	}
	return(status);
}

int saferead(int fd,void *buf,size_t count)
{
	int retval;

	retval=read(fd,buf,count);
	if(retval==-1)
		HandleError(errno,"read","read %d bytes from fd %d failed",(int)count,fd);
	return retval;
}

int safewrite(int fd,void *buf,size_t count)
{
	int retval;

	retval=write(fd,buf,count);
	if(retval==-1)
		HandleError(errno,"write","write %d bytes from fd %d failed",(int)count,fd);
	return retval;
}