42_SIDE_exam_06_miniserv/mini_serv_eric.c

// #include <errno.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>

typedef struct s_clients {
	int id;
	char msg[1024];
}	t_clients;

// so we just have a table of clients, no need to worry about linked lists, yea sounds good to me
t_clients	clients[1024];	// 1024 otherwise would have to change FD_SETSIZE and why bother
fd_set		readfds, writefds, active;
int			fd_Max = 0;
int			id_Next = 0;
char		bufread[120000];
char		bufwrite[120000];

void ft_error(char *str)
{
	// 2 is stderr i guess
	if (str)
		write(2, str, strlen(str));
	else
		write(2, "Fatal error", strlen("Fatal error"));
	write(2, "\n", 1);
	exit(1);
}

// not is the fd that send the message meaning you should not send that message to that fd
void	send_to_all(int not)
{
	for(int i = 0; i <= fd_Max; i++)
	{
		// have to check cuz we use an array not a linked list
		if (FD_ISSET(i, &writefds) && i != not)
			send(i, bufwrite, strlen(bufwrite), 0);	// man send explains things well
	}
}


int	main(int ac, char **av)
{

	if (ac != 2)
		ft_error("Wrong number of arguments");

	// just like in main.c
	// all this is explained in the man socket, cool
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd < 0)
		ft_error(NULL);
	
	// like bzeroing i guess but for the struct fd_set, yea it clears the set, none are active
	FD_ZERO(&active);
	// i think this gets all the contents of the structs as well ? yes cuz it's an array not a linked list so easy to bzero
	bzero(&clients, sizeof(clients));
	fd_Max = sockfd; // not sure what that does, none of this is in main.c
	FD_SET(sockfd, &active); // we add sockfd to active, ok cool

	struct sockaddr_in	servaddr;	// like in main.c
	socklen_t			len;	// not in main.c, i mean it kinda is but i prefer doing it this way, not even that important
	bzero(&servaddr, sizeof(servaddr)); // in main.c
	servaddr.sin_family = AF_INET;	// like main.c
	servaddr.sin_addr.s_addr = htonl(2130706433);	// like main.c
	servaddr.sin_port = htons(atoi(av[1]));	// slightly different than main.c cuz have to get the right port

	// just like main.c, we bind and listen, normal stuff that requres specific numbers
	if ((bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr))) < 0)
		ft_error(NULL);
	if (listen(sockfd, 10) < 0)
		ft_error(NULL);

	// no longer like main.c
	while(1)
	{
		readfds = active;
		writefds = active;
	
		// so like if it didn't add a new one? it continues? yea idk something about making sure select has happened
		if (select(fd_Max + 1, &readfds, &writefds, NULL, NULL) < 0)
			continue;
		
		// we cycle through all the FDs we've assigned at one point so far (they may not all be active)
		for (int fd_i = 0; fd_i <= fd_Max; fd_i++)
		{
			// for each one we check if it's set, and check if is or isn't sockfd
			// ohhh this is if a client just arrived
			if (FD_ISSET(fd_i, &readfds) && fd_i == sockfd)
			{
				// try to accept a new connection
				int	connfd = accept(sockfd, (struct sockaddr*)&servaddr, &len);	// more or less in main.c
				if (connfd < 0)
					continue;	// non blocking but this one didn't work
				// reset fd_max
				fd_Max = connfd > fd_Max ? connfd : fd_Max;	// whichever is larger is the new max
				clients[connfd].id = id_Next++;	// we add the new client
				FD_SET(connfd, &active);	// add it to the list
				sprintf(bufwrite, "server: client %d just arrived\n", clients[connfd].id);	// create message to send out
				send_to_all(connfd);
				break;
			}
			// things other than a new connection i guess
			if (FD_ISSET(fd_i, &readfds) && fd_i != sockfd)
			{
				// 65536 is just a big number i think
				int res = recv(fd_i, bufread, 65536, 0); // similar to send, also see man recv, it's good
				// something happened to a client so we tell the others this one is gone and handle clears and prevent leaks and such
				if (res <= 0) // -1 is error and 0 is end of file
				{
					sprintf(bufwrite, "server: client %d just left\n", clients[fd_i].id);
					send_to_all(fd_i);
					FD_CLR(fd_i, &active);
					close(fd_i);
					break;
				}
				else
				{
					// we read the whole message we just received and then send it out
					for(int i = 0, j = strlen(clients[fd_i].msg); i < res; i++, j++)
					{
						clients[fd_i].msg[j] = bufread[i];
						if (clients[fd_i].msg[j] == '\n')
						{
							clients[fd_i].msg[j] = '\0';
							sprintf(bufwrite, "client %d: %s\n", clients[fd_i].id, clients[fd_i].msg);
							send_to_all(fd_i);
							bzero(clients[fd_i].msg, strlen(clients[fd_i].msg));
							j = -1;	// becomes 0 right after this at the end of the loop, i think
						}
					}
					break;
				}
			}
		}
	}

	return (0);
}