client-server programs

[ariel_au]

i am learning to write UNIX socket and client programs.

i wrote the UNIX socket server program, this program uses a socket to wait for any incoming messages and then displays them on screen. i use the server ports 5010 to 5019.

and i compile server.c with the command "gcc server.c -o server -lsocket -lnsl".


i also wrote the UNIX socket client program, client.c that will send messages to the server program. i compile the program using gcc compiler; "gcc client.c -o client -lsocket -lnsl"

i tested the programs using two telnet sessions (one for server program and other for client program) at my PC. ( both telnet sessions r logged to the remote UNIX system and i just run both programs there.)

my problem is, the server does not display messages on screen when the client send messages to this server. ( i don't know where is the problem)

how can i modify both programs such that the server sends a reply message to the client upon receipt of a client's message??

below is the client.c and server.c

//client.c; usage: client port_number  host_name. application:client process sends packets to server process
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#include<stdio.h>
#define bcopy(b1, b2, len)	memmove(b1, b2, (size_t)(len))
#define bzero(b, len)	memset(b, 0, (size_t)(len))
#define bcmp(b1,b2,len)	memcmp(b1, b2, (size_t)(len))
#define bufsize 128

int sc, s1, len;
struct hostent*hp;
struct sockaddr_in tosever;
main(argc, argv)
int argc; char*argv[];
{
	char buf[bufsize];


	sc = socket(AF_INET, SOCK_STREAM, 0);

	bzero((char*)&tosever, sizeof(tosever));
	tosever.sin_family = AF_INET;
	tosever.sin_port = htons(atoi(argv[1]));

	if ((hp=gethostbyname(argv[2]))==NULL){
	fprintf(stderr, "%s- unknown host.\n", argv[2]);
	exit(-1);
	}

	bcopy(hp->h_addr, (char*)&tosever.sin_addr, hp->h_length);
	s1 = connect(sc,(struct sockaddr*)&tosever, sizeof(tosever));

	printf("Enter your message: \n");
	len = read(0, buf, bufsize);
	s1=send(sc,buf,len,0);
	close(sc);
	exit(0);
}
//--------------------------------------------------------------------------
//server.c; usage:server port_number where port_num is greater than 1023. Application: server listens to a specific port. when a msg is receives, server displays it on screen and exits.
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#include<stdio.h>
#define bcopy(b1, b2, len)	memmove(b1, b2, (size_t)(len))
#define bzero (b, len)	memset(b, 0,size_t)(len))
#define bcmp (b1, b2, len)	memcmp(b1, b2, (size_t)(len))
#define bufsize 128

main(argc, argv)
int argc; char*argv[];
{

	int snew, ss, len, lenc;
	char buf[bufsize];
	struct sockaddr_in name, cli_addr;


	name.sin_family = AF_INET;
	name.sin_addr.s_addr = INADDR_ANY;
	name.sin_port = htons(atoi(argv[1]));

	ss = socket(AF_INET, SOCK_STREAM, 0);

	bind(ss, (struct sockaddr*)&name, sizeof(name));

	listen(ss,1);
	lenc = sizeof(cli_addr);
	snew = accept(ss, (struct sockaddr*)&cli_addr, &lenc);

	len = recv(snew, buf, sizeof(buf), 0);
	buf[len] = NULL;
	printf("Message received....%s\n", buf);
	close(ss);
	exit(0);
}

[abdul]

I have not used UNIX but why not wait for the data to come and then say that the data is recieved like:

              int i;
              //................................

                while (i != 0)
                {
               len = recv(snew, buf, sizeof(buf), 0);
    buf[len] = NULL;

                }
                printf("Message received....%s\n", buf);
                 //....................