I'm making server for simple Memory Game.
I need little help with decomposition in my program, I know what I want but I don't know how should I write it in C, cause I don't have many experiences with using fork(). There is description of my purposes, "SKELETON" of my server - work sending and receiving messages, compiled without warnings or errors, IN THE END I'll ask my question.
This is example how could memory game works: Memory game example
And I'm solving problem with managing something like game "sessions".
Server is in C and client in Java, all will run it on linux. So it's to background info.
I'll have one server and n clients.
My motivation is:
1. Server starts on some address and port.
2. clients can connect to a server.
3. server will manage games.
Situation server:
game1 -client1, client2
game2 -client3, client4
...
gameN-clientX, clientY. (note: N is obviously not same as n)
Number of games will be about 10.
If there is more clients than a server - they have a shame .. I will somehow tell them that server is full.
each game is represented by an array of 64 int values - it represents numbers of icons
may be also array of bool length 64 and some variables (but it's just detail)
this array and variables will represent a state of each game and server and client will be communicating by string messages, I decode them and update the game state.
What I mean by game managing:
At the beginning there is no server- so I run the server (only one instance can exist).
1.Server wait for connection of clients, there is no game on server.
2. I run client, client decide to connect the server (ip, port). Server send's to client state of server - is there games? if yes, what games = (descriptor of games to be able to handle with games)?
3. Client has 1 to 3 options:
-a)create game = server generate staring game state, send info to client (if there is no game on server client has obviously only this option).
-b)if there some games client can connect to "prepared game" = some other client created the game and wait for opponent; client get the info abou game state and set his game state acording server.
c)there was already some game in progress, but one client from some reason lost the connection, so client want connect back to the game which is in progress - if some conditions will be accepted, server will sent him a game state so the can continue
4. Game which has 2 clients can begin.
5. Client which on the move can click on the button, so client get message which describe that action
6. server decide how the action will be procesed and send the the message to the BOTH of clients (something like OBSERVER) what should the do, clients probably confirm the message but this is again just detail
7. If the server crash or will be closed before end of the games, all games will be lost, I just do in clients something like if the server is down, they will write some message and end
8.If the game end properly - the game ends or one client decide to end game by chosing in menu end game, server do the stuff to acknowledge clients about end of game and the game will be deleted of list of games and there will be again position for new game.
Code of my server:
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h> // kvuli inet_ntop
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#define MYADDRESS "127.0.0.1" // the port users will be connecting to
#define MYPORT 10000 // the port users will be connecting to
#define MYFRONTA 10 // length of queue
#define MYMSGLEN 80 //max len of message
int sendMessage(char* msg, int socket){
int length = strlen(msg);
int ret;
ret = write(socket, msg, length);
return ret;
}
int readLine(void *vptr, size_t maxlen, int sockd) {
int n, rc;
char c, *buffer;
buffer = vptr;
for ( n = 1; n < maxlen; n++ ) {
if ( (rc = read(sockd, &c, 1)) == 1 ) {
*buffer++ = c;
if ( c == '\n' )
break;
}
else if ( rc == 0 ) {
if ( n == 1 )
return 0;
else
break;
}
}
*buffer = 0;
return n;
}
int main(int argc, char **argv)
{
int server_sockfd, client_sockfd;
socklen_t server_len, client_len;
struct sockaddr_in server_address;
struct sockaddr_in client_address;
server_sockfd = socket( AF_INET, SOCK_STREAM, 0 );
server_address.sin_family = AF_INET;
server_address.sin_addr.s_addr = inet_addr( MYADDRESS );
server_address.sin_port = htons( MYPORT );
server_len = sizeof( server_address );
//If the server binding fails
if( bind( server_sockfd, ( struct sockaddr *)&server_address, server_len ) != 0 )
{
perror("oops: server-tcp-single");
exit( 1 );
}
listen( server_sockfd, MYFRONTA );
signal( SIGCHLD, SIG_IGN );//Zombie process protection
while( 1 )
{
printf( "server wait...\n" );
client_len = sizeof( client_address );
client_sockfd = accept( server_sockfd, ( struct sockaddr *)&client_address, &client_len );
//Info
char str[INET_ADDRSTRLEN];
inet_ntop(AF_INET,&(client_address.sin_addr), str, INET_ADDRSTRLEN);
printf( "Connected client from %s\n", str );
if( fork() == 0 )
{
char retezec[MYMSGLEN];
readLine(retezec, MYMSGLEN, client_sockfd);
printf( "Klient sent : %s\n", retezec );
printf( "Server sends : %s\n", retezec );
sendMessage(retezec, client_sockfd);
close( client_sockfd );
exit (0 );
}
else
close( client_sockfd );
}
return EXIT_SUCCESS;
}
So my question is: I have to serve each client or game in separate process and need help with decomposition. Where should I place variables (arrays, variables) for each games? According to the fork().
