sdl-audio/net.c

#include "net.h"
#include "log.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

typedef struct {
	struct sockaddr_in addr;
	int socket;
	socklen_t addr_len;
} net_info;

typedef struct peer_addr_node {
	struct sockaddr_in addr;
	time_t time_last;
	time_t time_elapsed;
	struct peer_addr_node* next;
} peer_addr_node;
static peer_addr_node* peer_list = NULL;

static int peer_list_add(struct sockaddr_in* addr);
static int peer_list_exists(struct sockaddr_in* addr);
static void peer_list_destroy();

static net_info broadcast_info;
static net_info listen_info;
static net_info peer_info;
static int PORT;

static int init = 0;

int net_init(unsigned int port)
{
	PORT = port;
	// broadcast socket
	broadcast_info.socket = socket(AF_INET, SOCK_DGRAM, 0);
	if (broadcast_info.socket < 0) {
		log_message(LOG_ERROR, "Error creating broadcast socket");
		close(broadcast_info.socket);
		return 0;
	}

	int broadcast_enable = 1;
	if (setsockopt(broadcast_info.socket, SOL_SOCKET, SO_BROADCAST, &broadcast_enable, sizeof(broadcast_enable)) < 0) return 0;

	memset(&broadcast_info.addr, 0, sizeof(broadcast_info.addr));
	broadcast_info.addr.sin_family = AF_INET;
	broadcast_info.addr.sin_addr.s_addr = inet_addr("255.255.255.255");
	broadcast_info.addr.sin_port = htons(port);

	broadcast_info.addr_len = sizeof(broadcast_info.addr);

	// listen socket
	listen_info.socket = socket(AF_INET, SOCK_DGRAM, 0);
	if (listen_info.socket < 0) {
		log_message(LOG_ERROR, "Error creating listen socket", strerror(errno));
		close(listen_info.socket);
		return 0;
	}

	int reuse_enable = 1;
	if (setsockopt(listen_info.socket, SOL_SOCKET, SO_REUSEADDR, &reuse_enable, sizeof(reuse_enable)) < 0) return 0;

	memset(&listen_info.addr, 0, sizeof(listen_info.addr));
	listen_info.addr.sin_family = AF_INET;
	listen_info.addr.sin_addr.s_addr = INADDR_BROADCAST;
	listen_info.addr.sin_port = htons(port);

	listen_info.addr_len =sizeof(listen_info.addr);

	struct timeval tv;
	tv.tv_sec = 0;
	tv.tv_usec = 100000;
	setsockopt(listen_info.socket, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));

	if (bind(listen_info.socket, (const struct sockaddr*)&listen_info.addr, sizeof(listen_info.addr)) < 0) {
		log_message(LOG_ERROR, "Socket bind failed: %s", strerror(errno));
		close(listen_info.socket);
		return 0;
	}

	peer_info.socket = -1;

	init = 1;
	return 1;
}

void net_destroy()
{
	close(broadcast_info.socket);
	close(listen_info.socket);
	close(peer_info.socket);
	peer_list_destroy();
}

int net_broadcast()
{
	if (!init) return 0;;
	const char* message = "broadcast message";
	int retv = sendto(broadcast_info.socket, message,
	                  strlen(message), 0,
	                  (struct sockaddr*)&broadcast_info.addr,
	                  broadcast_info.addr_len);
	if (retv < 0) {
		log_message(LOG_ERROR, "Failed to send broadcast message: %s", strerror(errno));
		log_message(LOG_ERROR, "retv: %i", retv);
		return 0;
	}
	log_message(LOG_INFO, "Broadcast message sent");
	return 1;
}

int net_listen_peers()
{
	if (!init) return 0;

	net_info broadcast_listen;

	broadcast_listen.socket = socket(AF_INET, SOCK_DGRAM, 0);
	if (broadcast_listen.socket < 0) {
		log_message(LOG_ERROR, "Error creating listen socket", strerror(errno));
		close(broadcast_listen.socket);
		return 0;
	}

	char buffer[64];

	memset(&broadcast_listen.addr, 0, sizeof(broadcast_listen.addr));
	broadcast_listen.addr.sin_family = AF_INET;
	broadcast_listen.addr.sin_addr.s_addr = INADDR_ANY;
	broadcast_listen.addr.sin_port = htons(PORT);

	broadcast_listen.addr_len = sizeof(broadcast_listen.addr);

	int retv = recvfrom(listen_info.socket, buffer, sizeof(buffer), 0,
	                    (struct sockaddr*)&broadcast_listen.addr,
	                    &broadcast_listen.addr_len);

	close(broadcast_listen.socket);

	if (retv < 0) {
		if (errno != EAGAIN)
			log_message(LOG_ERROR, "Failed to receive broadcast message: %s", strerror(errno));
		close(broadcast_listen.socket);
		broadcast_listen.socket = -1;
		return 0;
	}

	buffer[retv] = '\0';

	log_message(LOG_INFO,
	            "Broadcast message received from:\n%s:%d\n%s",
	            inet_ntoa(broadcast_listen.addr.sin_addr),
	            ntohs(broadcast_listen.addr.sin_port),
	            buffer);

	retv = peer_list_exists(&broadcast_listen.addr);
	if (retv) return 0;

	peer_list_add(&broadcast_listen.addr);

	return 1;
}

int net_prune_peers()
{
	if (!init) return 0;
	if (!peer_list) return 0;
	int pruned = 0;
	peer_addr_node* node = peer_list;
	peer_addr_node* last_node = NULL;
	while (node) {
		peer_addr_node* next_node = node->next;

		node->time_elapsed += time(NULL) - node->time_last;
		node->time_last = time(NULL);

		if (node->time_elapsed < CLIENT_MAX_TIME) {
			last_node = node;
			goto next;
		}

		pruned = 1;
		free(node);
		if (node == peer_list)
			peer_list = next_node;
		if (last_node != NULL)
			last_node->next = next_node;
next:
		node = next_node;
	}
	return pruned;
}

int net_send(void* buffer, size_t size)
{
	if (!init) return 0;
	if (peer_info.socket < 0) return 0;
	return 1;
}

int net_receive()
{
	if (!init) return 0;
	return 1;
}

void net_print_peers()
{
	if (!peer_list) return;
	peer_addr_node* node = peer_list;
	while (node) {
		log_message(LOG_INFO,
		            "Peers :\n%s:%d",
		            inet_ntoa(node->addr.sin_addr),
		            ntohs(node->addr.sin_port));
		node = node->next;
	}
}

int net_get_peers(struct sockaddr_in** peer_addr)
{
	if (!peer_list) return 0;
	static peer_addr_node* node = NULL;
	static int done = 0;

	if (done) {
		done = 0;
		return 0;
	}

	if (!node) node = peer_list;
	*peer_addr = &node->addr;

	if (!node->next) done = 1;
	node = node->next;
	return 1;
}

static int peer_list_add(struct sockaddr_in* addr)
{
	peer_addr_node* new_node = malloc(sizeof(peer_addr_node));
	size_t size = sizeof(struct sockaddr_in);
	memset(&new_node->addr, 0, sizeof(size));
	memcpy(&new_node->addr, addr, sizeof(size));
	new_node->time_last = time(NULL);
	new_node->time_elapsed = 0;
	new_node->next = peer_list ? peer_list : NULL;
	peer_list = new_node;
	return 1;
}

static int peer_list_exists(struct sockaddr_in* addr)
{
	if (!peer_list) return 0;
	peer_addr_node* node = peer_list;
	while (node) {
		int address_match = addr->sin_addr.s_addr == node->addr.sin_addr.s_addr;
		int port_match = addr->sin_port == node->addr.sin_port;
		if (address_match && port_match) {
			node->time_elapsed = 0;
			return 1;
		}
		node = node->next;
	}
	return 0;
}

static void peer_list_destroy()
{
	peer_addr_node* node = peer_list;
	while (node) {
		peer_addr_node* next_node = node->next;
		free(node);
		node = next_node;
	}
}