TCP Server - Client Archives - Konstantinos Chalvantzis / Κωνσταντίνος Χαλβαντζής

C Code

TCP – Server

defs.h

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define SERV_TCP_PORT 6000

#define SERV_HOST_ADDR “127.0.0.1”

char *pname;

utils.c

#include “defs.h”

#define MAXLINE 512

/* Read n bytes from a descriptor. Use it in place of read() when fd is a stream socket. */
int readn(fd, ptr, nbytes)
register int fd;
register char *ptr;
register int nbytes;
{
int nleft, nread;
nleft=nbytes;

while (nleft>0)
{
nread=read(fd, ptr, nleft);

if (nread<0) return(nread); /* error */
else if (nread==0) break; /* EOF */
nleft -=nread; ptr+=nread;
}
return(nbytes-nleft);
}

/* Write n bytes from a descriptor. Use it in place of write() when fd is a stream socket. */
int writen(fd, ptr, nbytes)
register int fd;
register char *ptr;
register int nbytes;
{
int nleft, nwritten;
nleft=nbytes;
while (nleft>0)
{
nwritten=write(fd,ptr, nleft);
if (nwritten<=0)
return(nwritten); /* error */
nleft -=nwritten;
ptr+=nwritten;
}

return(nbytes-nleft);
}

/* Read a line from a descriptor. Read the line one byte at a time,
looking for the newline. We store the newline in the buffer, then
follow it with a null. We return the number of characters up to,
but not including, the null. */

int readline(fd, ptr, maxlen)
register int fd;
register char *ptr;
register int maxlen;

{
int n,rc;
char c;
for (n=1; n<maxlen;n++)
{
if ((rc=read(fd,&c,1))==1)
{
*ptr++=c;
if(c==’\n’) break;
}
else if (rc==0)
{
if (n==1) return(0); /* EOF no data read */
else break; /* EOF, some data was read */
}
else return(-1); /* error */
}
*ptr=0;

return(n);
}

/* Read a stream socket one line at a time and write each line back to the sender.
Return when the connection is terminated. */
str_echo(sockfd) int sockfd;
{
int n; char line[MAXLINE];
for ( ; ; )
{
n = readline(sockfd, line, MAXLINE);

if (n==0) return; /* connection terminated */
else if (n < 0) printf(“str_echo: readline error\n”);
if (writen(sockfd, line, n) != n)
printf(“str_echo: writen error\n”);
}
}

/* read the contents of the FILE *fp, write each line to the stream socket (to the server process),
then read a line back from the socket and write it to the standard output.
Return to caller when an EOF is encountered on the input file. */

str_cli(fp, sockfd)
register FILE *fp;
register int sockfd;
{

int n;
char sendline[MAXLINE], recvline[MAXLINE+1];

while(fgets(sendline, MAXLINE, fp) !=NULL)
{
n=strlen(sendline);
if (writen(sockfd,sendline,n)!=n)
printf(“str_cli: writen error on socket\n”);
/* Now read a line from the socket and write it to our standard output */
n=readline(sockfd,recvline,MAXLINE);
if (n<0) printf(“str_cli: readline error\n”); recvline[n]=0; /* null terminate */
fputs(recvline,stdout);
}
}

server.c

#include “defs.h”
#include “utils.c”

main(argc, argv)
int argc;
char *argv[];
{
FILE *fp;
char filename[100];
int sockfd, newsockfd, clilen, childpid,n;
struct sockaddr_in cli_addr, serv_addr; pname=argv[0];

if ((sockfd=socket(AF_INET,SOCK_STREAM,0)) <0)
{
printf(“server: can’t open stream socket\n”);
exit(0);
}

bzero((char*) &serv_addr, sizeof(serv_addr));

serv_addr.sin_family=AF_INET;
serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);
serv_addr.sin_port=htons(SERV_TCP_PORT);

if(bind(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
{
printf(“server: can’t bind local address\n”);
exit(0);
}

listen(sockfd,5);

for ( ; ; )
{
clilen=sizeof(cli_addr);
newsockfd=accept(sockfd,(struct sockaddr *) &cli_addr,&clilen);

if(newsockfd < 0)
{
printf(“server: accept error\n”);
exit(0);

}

if((childpid=fork()) <0)
{
printf(“server: fork error\n”);
exit(0);
}
else if (childpid==0)
{
close(sockfd);
if((n=readn(newsockfd,filename,sizeof(filename))) <= 0)
{
printf(“server: filename read error\n”);
}
filename[n]=’\0′;
if ((fp=fopen(filename,”r”)) == NULL)
{
printf(“De mporo na anoikso to arxeio\n”);
exit(-1);
}
str_cli(fp, newsockfd);
/*str_echo(newsockfd);*/
fclose(fp);
exit(0);
}
close(newsockfd);
}
}

TCP – Client

defs.h

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define SERV_TCP_PORT 6000

#define SERV_HOST_ADDR “127.0.0.1”

char *pname;

utils.c

#include “defs.h”

#define MAXLINE 512

while (nleft>0)
{
nread=read(fd, ptr, nleft);

if (nread<0) return(nread); /* error */
else if (nread==0) break; /* EOF */
nleft -=nread; ptr+=nread;
}
return(nbytes-nleft);
}

return(nbytes-nleft);
}

int readline(fd, ptr, maxlen)
register int fd;
register char *ptr;
register int maxlen;

return(n);
}

if (n==0) return; /* connection terminated */
else if (n < 0) printf(“str_echo: readline error\n”);
if (writen(sockfd, line, n) != n)
printf(“str_echo: writen error\n”);
}
}

str_cli(fp, sockfd)
register FILE *fp;
register int sockfd;
{

int n;
char sendline[MAXLINE], recvline[MAXLINE+1];

client.c

#include “defs.h”
#include “utils.c”

main(argc, argv)
int argc;
char *argv[];
{
char filename[100];
int sockfd;
struct sockaddr_in serv_addr;
pname=argv[0];
bzero((char*) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family=AF_INET;
serv_addr.sin_addr.s_addr=inet_addr(SERV_HOST_ADDR);
serv_addr.sin_port=htons(SERV_TCP_PORT);

if((sockfd=socket(AF_INET,SOCK_STREAM,0)) < 0)
{
printf(“client: can’t open stream socket\n”);
exit(0);
}

if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
{
printf(“client: can’t connect to server\n”);
exit(0);
}

/*////////////////////////*/
printf(“Dose to onoma tou arxeiou:\n”);
scanf(“%s”,&filename);
writen(sockfd,filename,sizeof(filename));

/*str_cli(stdin, sockfd);*/
str_echo(sockfd);
/*////////////////////////*/

close(sockfd);
exit(0);
}