Programming

I have been trying to write a very basic chat program but at the moment I am having problems getting it to be multiuser as it closes all connections when one client shutsdown. I have also been having problems trying to get the program to display a list of usernames to the clients. I have tried setting the msg_type to '2' so that it will process the usernames list with a different function but the message type appears to be 512 on the server program and 7 on the client. I would be very grateful if someone could help me as I am new to this. Thanks.

Code for Server:

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/time.h>

#define MAX_CLIENTS 64

struct sockaddr_in sv_addr;
int addr_len;
struct sockaddr addr;
struct sockaddr_in *ptr;
int cl_addr_len;
struct sockaddr_in cl_addr;
char in_buf[100], out_buf[100];
char names [10][30];
char message[150];
int num_names = 0;

typedef struct cl_info
{
char cl_id[30];
int cl_status;
}cl_info;

cl_info clients[MAX_CLIENTS];

int main(int argc, char **argv)
{
int newsockfd;
int sockfd;
int nbytes;
int max_fd;
int fd;
short func_num;

fd_set test_set, ready_set;

sockfd = socket(AF_INET, SOCK_STREAM, 0);
sv_addr.sin_family - AF_INET;
sv_addr.sin_port = 0; /*choose an unused port at random */
sv_addr.sin_addr.s_addr = INADDR_ANY; /* auto fill with my IP address */
bind(sockfd, &sv_addr, sizeof(sv_addr));
addr_len = sizeof(addr);
getsockname(sockfd, &addr, &addr_len);
ptr = (struct sockaddr_in *)&addr;
printf("\nServer on port# %d\n", ptr->sin_port);
listen(sockfd, 5);
max_fd = sockfd;
FD_ZERO(&test_set); /*clear the listening socket */
FD_SET(sockfd, &test_set);

while(1)
{
memcpy(&ready_set, &test_set, sizeof(test_set));
select(max_fd+1, &ready_set, NULL, NULL, NULL);
if(FD_ISSET(sockfd, &ready_set)) /*if listening sock has data its a call from new client */
{
/*create a new socket */
cl_addr_len = sizeof(cl_addr);
newsockfd = accept(sockfd, (struct sockaddr *)&cl_addr, &cl_addr_len);
printf("\nA new connection has been made to socket %d\n", newsockfd);
FD_SET(newsockfd, &test_set); /* add new socket to list */
if(newsockfd > max_fd)
max_fd = newsockfd; /*update max_fd with new socket file discriptor */
} /*end if*/
for(fd=0; fd <= max_fd; fd++) /*loop through connected socket file discriptors */
{
if((fd !=sockfd) && FD_ISSET(fd, &ready_set))/*bypass listening sock if sock has data*/
if(process_call(fd, max_fd) == 0) /*if socket is closed */
{
printf("\nThe listening socket is now closed\n");
close(newsockfd);
printf("\nClient on socket %d has left the room\n", sockfd);
FD_CLR(fd, &test_set); /*remove socket from list */
/*decrement user count */
} /*end if */
} /* end for loop */
} /*end while loop */
return 0;
} /*end main */
int add_name(int sockfd)
{
int nbytes;
short name_len;
short n_name_len;

printf("\nAdding name .....\n");
nbytes = read(sockfd, (char *)&name_len, sizeof(short));
name_len = ntohs(name_len); /*convert name_len from network to host short */
memset(clients[sockfd].cl_id, 0, 30); /*set all bytes to zero */
nbytes = read(sockfd, clients[sockfd].cl_id, name_len);
num_names ++; /*increment user count */
printf("\n%s has joined the chat room\n", clients[sockfd].cl_id);

/*need to broadcast user has joined plus user id to connected clients here */

} /*end add_name function */
int how_many(int sockfd, int max)
{
int sock;
short user_len;
char username[30];

for(sock = 4; sock <= max; sock++)
{
strcpy(username, clients[sock].cl_id);

user_len = htons(strlen(username));
write(sockfd, (char *)&user_len, sizeof(short));
write(sockfd, username, strlen(username));
send_user_list(sockfd, username);
}
} /*end how_many function */
int send_user_list(int sockfd, char *users)
{
short msg_type;
short user_len;

msg_type = htons(2);
printf("msg_type is : %u\n", msg_type);
write(sockfd, &msg_type, sizeof(short));

user_len = htons(strlen(users));
write(sockfd, (char *)&user_len, sizeof(short));
write(sockfd, users, strlen(users));
}
int find_name(int sockfd, int max)
{
char search_name[30];
int sock;
int found = 0;
short len, name_len;
char sender[30];
short sender_len;
char msg[150];
short msg_len;

memset(search_name, 0, 30); /*set all bytes to zero */
printf("\nReceiving userid......\n");
read(sockfd, (char *)&name_len, sizeof(short));
len = ntohs(name_len);
read(sockfd, search_name, len);
read(sockfd, &msg_len, sizeof(short));
msg_len = ntohs(msg_len);
read(sockfd, msg, msg_len);
msg[msg_len] = '\0';

strcpy(sender, clients[sockfd].cl_id);

for(sock = 4; sock <= max; sock++)
{
printf(" %d is held in max\n", max);
printf("\ncomparing search request for %s with %s username\n",
search_name, clients[sock].cl_id);
if(strcmp(search_name, clients[sock].cl_id) ==0)
{
printf("\nuserid found\n");
found = 1;
send_async_msg(sock, msg,sender);
}/*end if */
} /*end for loop */

if(! found)
{
printf("\nuserid not found\n");
} /*end if */
}/*end find_name function */
int process_call(int newsockfd, int max_fd)
{
int nbytes;
short func_num;

nbytes = read(newsockfd, (char *)&func_num, sizeof(short));
if(nbytes ==0)
return 0;
if (nbytes != sizeof(short))
{
perror("\nUnknown menu option!\n");
exit(1);
} /* end if */

func_num = ntohs(func_num);
switch(func_num)
{
case(1):
add_name(newsockfd);
break;
case(2):
how_many(newsockfd, max_fd);
break;
case(3):
find_name(newsockfd, max_fd);
break;
case(4):
send_global_msg(newsockfd, max_fd);
break;
case(5):
printf("\nShutting down Server...\n");
exit(0);
default:
printf("\nUnknown function number!\n");
break;
} /*end switch */
} /*end process_call function */
int send_async_msg(int sockfd, char * msg, char *sender)
{
short msg_type;
short msg_len;
short sender_len;

msg_type = htons(1);
printf("msg_type is : %u\n", msg_type);
write(sockfd, &msg_type, sizeof(short));
msg_len = htons(strlen(msg));
write(sockfd, (char *)&msg_len, sizeof(short));
write(sockfd, msg, strlen(msg));

sender_len = htons(strlen(sender));
write(sockfd, (char *)&sender_len, sizeof(short));
write(sockfd, sender, strlen(sender));
}/* end of send_async_msg function */
int send_global_msg(int sockfd, int max_fd)
{
int nbytes;
int sock;
short len;
short msg_type;
char msg[150];
char sender[30];
short sender_len;

strcpy(sender, clients[sockfd].cl_id);

msg_type = 1;
memset(in_buf, 0, sizeof(in_buf)); /*set all to zero */
nbytes = read(sockfd, &len, sizeof(short));
len = ntohs(len);
read(sockfd, msg, len);
message[len] = '\0';
for(sock = 4; sock <= max_fd; sock++)
{
send_async_msg(sock, msg, sender);
} /*end for loop */
} /* end of send_global_msg function */

CODE for Client: is in attached txt file