simple client server in c - c

Question

i am not able to understand why the code is not working. sendall and revcall are taken from beej guide. Their is no output when i send the data from server to client. Can someone please explain the error in code. It is mostly from beej guide.One of the problems in broken pipe i.e reading when port is closed but when the port is closed i am not able to understand.
server code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define MAX_SIZE 50
void error(const char *msg)
{
perror(msg);
exit(1);
}
/* sends all data - thanks to Beej's Guide to Network Programming */
int sendall(int s, char *buf, int *len)
{
int total=0;
int bytesleft=*len;
int n=0;
/* send all the data */
while(total<*len)
{
/* send some data */
n=send(s,buf+total,bytesleft,0);
/* break on error */
if(n==-1)
break;
/* apply bytes we sent */
total+=n;
bytesleft-=n;
}
/* return number of bytes actually send here */
*len=total;
/* return -1 on failure, 0 on success */
return n==-1?-1:0;
}
int main(int argc, char *argv[])
{
int sockfd, newsockfd, portno;
socklen_t clilen;
char buffer[256];
struct sockaddr_in serv_addr, cli_addr;
int n;
if (argc < 2)
{
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
printf("sockfd : %d",sockfd);
if (sockfd < 0)
error("ERROR opening socket");
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
if(bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
error("ERROR on binding");
listen(sockfd,5);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
if (newsockfd < 0)
error("ERROR on accept");
char msg[1024] = "hello";
int len = sizeof(msg);
int xx = sendall(sockfd,(char*)msg,&len);
close(newsockfd);
close(sockfd);
return 0;
}
client code
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include<errno.h>
void error(const char *msg)
{
perror(msg);
exit(0);
}
/* receives all data - modelled after sendall() */
int recvall(int s, char *buf, int *len, int timeout)
{
int total=0;
int bytesleft=*len;
int n=0;
time_t start_time;
time_t current_time;
/* clear the receive buffer */
bzero(buf,*len);
time(&start_time);
/* receive all data */
while(total<*len)
{
/* receive some data */
n=recv(s,buf+total,bytesleft,0);
/* no data has arrived yet (non-blocking socket) */
if(n==-1 && errno==EAGAIN)
{
time(&current_time);
if(current_time-start_time>timeout)
break;
sleep(1);
continue;
}
/* receive error or client disconnect */
else if(n<=0)
break;
/* apply bytes we received */
total+=n;
bytesleft-=n;
}
/* return number of bytes actually received here */
*len=total;
/* return <=0 on failure, bytes received on success */
return (n<=0)?n:total;
}
int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[1024];
if (argc < 3)
{
fprintf(stderr,"usage %s hostname port\n", argv[0]);
exit(0);
}
portno = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");;
serv_addr.sin_port = htons(portno);
if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
int m = 1024;
n = recvall(sockfd, buffer,&m,10);
if (n < 0)
error("ERROR reading from socket");
printf("%s\n",buffer);
close(sockfd);
return 0;
}

Answer 1

'int xx = sendall(sockfd,(char*)msg,&len);'
'sockfd' is the server listening socket. You should be calling sendall() with 'newsockfd', as returned by the accept() call.