path: root/src/net.c

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <assert.h>
#include "net.h"

/**
 * Server side function; start server on specified port
 * @param[in] port Port on which server should listen
 * @return Listening socket
 */
int server_start(const char* port)
{
	int status;
	int serversock;
	struct addrinfo hints, *result, *tmp;

	memset(&hints, 0, sizeof(struct addrinfo));
	hints.ai_family = AF_UNSPEC;		// IPv4 or IPv6
	hints.ai_socktype = SOCK_STREAM;	// TCP socket
	hints.ai_flags = AI_PASSIVE;		// wildcard IP
	hints.ai_protocol = 0;			// any protocol

	status = getaddrinfo(NULL, port, &hints, &result);
	if(status != 0)
	{
		printf("getaddrinfo: %s\n", gai_strerror(status));
		exit(EXIT_FAILURE);
	}

	// iterate over linked addrinfo list and use first useable entry
	for(tmp = result; tmp != NULL; tmp = tmp->ai_next)
	{
		int yes=1;

		// create socket
		serversock = socket(tmp->ai_family, tmp->ai_socktype, tmp->ai_protocol);
		if(serversock == -1)
			continue;

		// try to reuse still open sockets in TIME_WAIT state
		setsockopt(serversock, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));

		// try to bind to address/port
		if(bind(serversock, tmp->ai_addr, tmp->ai_addrlen) == 0)
			break; // Success!

		close(serversock);
	}

	if(tmp == NULL)
	{
		printf("failed to bind\n");
		exit(EXIT_FAILURE);
	}
	freeaddrinfo(result);

	// start listening
	status = listen(serversock, 1);
	if(status == -1)
	{
		printf("listen: %s\n", strerror(status));
		exit(EXIT_FAILURE);
	}

	return serversock;
}

/**
 * Server side function; accepts connections from clients
 * @param[in] serversock Socket on which server is listening
 * @param[in] count Number of clients that should connect
 * @return List of $count open sockets with connections to clients
 */
int* server_get_players(int serversock, const uint8_t count)
{
	int* clientsocks;
	int i;

	assert(count < MAX_PLAYERS && count > 0);

	clientsocks = malloc(count*sizeof(int));
	assert(clientsocks != NULL);

	// accept connections
	for(i=0; i<count; i++)
	{
		int sock;
		struct sockaddr_storage addr;
		socklen_t addrlen = sizeof(addr);
		sock = accept(serversock, (struct sockaddr*) &addr, &addrlen);
		if(sock == -1)
		{
			printf("accept: %s\n", strerror(sock));
			exit(EXIT_FAILURE);
		}
		//printf("new client connected: %s\n", inet_ntop(sock.ss_family, get_in_addr((struct sockaddr*)&sock), INET6_ADDRSTRLEN));
		printf("new client connected (%d/%d)\n", i+1, count);
		clientsocks[i] = sock;
	}

	return clientsocks;
}

/**
 * Client side function; Send hello to server
 * @param[in] sock Socket to use
 * @param[in] username Username of player
 */
void client_hello(int sock, const char* username)
{
	uint8_t* buf;
	uint8_t namelen = strlen(username);

	buf = malloc(namelen+2); // type + len + username

	buf[0] = CLIENT_HELLO;
	buf[1] = namelen;
	memcpy(buf+2, username, namelen);

	send(sock, buf, namelen+2, 0);

	free(buf);
}

/**
 * Client side function; connects to specified host:port
 * @param[in] host Hostname of server
 * @param[in] port Port of server
 * @return Socket with open connection to server
 */
int client_connect_server(const char* host, const char* port)
{
	int status;
	int sock;
	struct addrinfo hints, *result, *tmp;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_UNSPEC;		// IPv4 or IPv6
	hints.ai_socktype = SOCK_STREAM;	// TCP socket

	status = getaddrinfo(host, port, &hints, &result);
	if(status != 0)
	{
		printf("getaddrinfo: %s\n", gai_strerror(status));
		exit(EXIT_FAILURE);
	}

	// connect to first result in linked addrinfo list
	for(tmp = result; tmp != NULL; tmp = tmp->ai_next)
	{
		// create socket
		sock = socket(tmp->ai_family, tmp->ai_socktype, tmp->ai_protocol);
		if(sock == -1)
			continue;

		// connect!
		if(connect(sock, tmp->ai_addr, tmp->ai_addrlen) != -1)
			break;	// Success!

		close(sock);
	}

	if(tmp == NULL)
	{
		printf("failed to connect\n");
		exit(EXIT_FAILURE);
	}
	freeaddrinfo(result);

	return sock;
}


void server_start_game(int* clients, const uint8_t clientcount, const char* usernames[])
{
	uint8_t* buf;
	uint8_t usercount = clientcount + 1; // 1 more user (server) than clients
	uint32_t pos = 0;
	uint32_t buflen = 2 + usercount; // type + usercount + (usercount * len)

	for(int i=0; i<usercount; i++)
		buflen += strlen(usernames[i]);

	buf = malloc(buflen);
	buf[pos++] = SERVER_START_GAME;
	buf[pos++] = clientcount;
	// copy usernames with length to buffer
	for(int i=0; i<usercount; i++)
	{
		uint8_t len = strlen(usernames[i]);
		buf[pos++] = len;
		memcpy(buf+pos, usernames[i], len);
		pos += len;
	}

	// send to all users
	for(int i=0; i<clientcount; i++)
		send(clients[i], buf, buflen, 0);

	free(buf);
}

/**
  * Server side function; receive hello message from client and read username
  * @param[in] sock Socket to use
  * @return Username of client
  */
char* server_recv_hello(int sock)
{
	char buf[12], *name;
	uint8_t namelen;

	recv(sock, buf, 13, 0);

	assert(buf[0] == CLIENT_HELLO);

	namelen = buf[1];
	name = malloc(namelen+1);
	strncpy(name, buf+2, namelen);
	name[namelen] = '\0';

	return name;
}

/**
  * Server side function; calls correct handler for incoming packet
  * @param[in] sock Socket to use
  * @param[in] wanted Packet type that should be handled
  * @return Pointer to desired data or NULL if not in recv queue
  */
void* server_recv(int sock, uint8_t wanted)
{
	void* result = NULL;
	uint8_t buf[10], type;
	ssize_t len = recv(sock, buf, 10, MSG_PEEK); // just peek into packet to determine type

	assert(len != -1);

	type = buf[0];
	if(type != wanted)
		return NULL;

	switch(type)
	{
		case CLIENT_HELLO:
			result = server_recv_hello(sock);
			break;
	}

	return result;
}