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/*
* Program: router
* Autor: Franciszek Malinka, 316093
*/
#include "utils.h"
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>
int get_socket() {
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
fprintf(stderr, "Socket error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
return sockfd;
}
void bind_to_port(int sockfd, uint16_t port) {
struct sockaddr_in server_address;
bzero(&server_address, sizeof(server_address));
server_address.sin_family = AF_INET;
server_address.sin_port = htons(port);
server_address.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(sockfd, (struct sockaddr*)&server_address, sizeof(server_address)) < 0) {
fprintf(stderr, "Bind error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
int broadcastPermission = 1;
setsockopt (sockfd, SOL_SOCKET, SO_BROADCAST, (void *)&broadcastPermission, sizeof(broadcastPermission));
}
long get_time_interval(struct timespec start, struct timespec finish) {
return S_TO_MS(finish.tv_sec - start.tv_sec) + NS_TO_MS(finish.tv_nsec - start.tv_nsec);
}
int poll_socket_modify_timeout(int sockfd, int *timeout) {
if (*timeout < 0) {
*timeout = 0;
return 0;
}
struct pollfd fds;
struct timespec start;
struct timespec finish;
fds.fd = sockfd;
fds.events = POLLIN;
fds.revents = 0;
clock_gettime(CLOCK_REALTIME, &start);
int result = poll(&fds, 1, *timeout);
clock_gettime(CLOCK_REALTIME, &finish);
if (result == -1) {
fprintf(stderr, "poll error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (result == 0) {
*timeout = 0;
return 0;
}
*timeout -= get_time_interval(start, finish);
return result;
}
size_t send_message(int sockfd, char *buffer, int buffer_len, struct in_addr network) {
struct sockaddr_in network_address;
bzero (&network_address, sizeof(network_address));
network_address.sin_family = AF_INET;
network_address.sin_port = htons(SERVER_PORT);
network_address.sin_addr = network;
return sendto(sockfd, buffer, buffer_len, 0, (struct sockaddr*) &network_address, sizeof(network_address));
}
size_t recv_message(int sockfd, char *buffer, struct sockaddr_in *sender) {
socklen_t sender_len = sizeof(*sender);
for (int i = 0; i < DV_DATAGRAM_LEN; i++) buffer[i] = 0;
size_t datagram_len = recvfrom(sockfd, buffer, IP_MAXPACKET, 0,
(struct sockaddr*)sender, &sender_len);
if (datagram_len < 0) {
fprintf(stderr, "recvfrom error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
return datagram_len;
}
struct vector_item parse_message(char *buffer, struct sockaddr_in *sender) {
struct vector_item res;
uint32_t ip_addr = *(uint32_t *)buffer;
uint32_t dist = *(uint32_t *)(buffer + 5);
dist = ntohl(dist);
res.network.addr.s_addr = ip_addr;
res.network.netmask = buffer[4];
res.is_connected_directly = true;
res.via_ip = sender->sin_addr;
res.distance = (dist < INFINITY_DIST ? dist : INFINITY_DIST);
res.reachable = 0;
char addr[20];
inet_ntop(AF_INET, &res.network.addr, addr, sizeof(addr));
char via[20];
inet_ntop(AF_INET, &sender->sin_addr, via, sizeof(via));
return res;
}
void _get_message(struct vector_item item, char *message) {
*(uint32_t *)message = item.network.addr.s_addr;
message[4] = item.network.netmask;
uint32_t distance = htonl(item.distance >= INFINITY_DIST ? INT_MAX : item.distance);
for (int i = 0; i < 4; i++) {
*(message + 5 + i) = *((char *)(&distance) + i);
}
}
int _send_item(int sockfd, struct network_addr network, struct vector_item item) {
char message[DV_DATAGRAM_LEN + 1];
_get_message(item, message);
message[DV_DATAGRAM_LEN] = 0;
ssize_t message_len = DV_DATAGRAM_LEN;
struct in_addr na = get_broadcast_address(network);
char addr[20];
inet_ntop(AF_INET, &na, addr, sizeof(addr));
int result;
if ((result = send_message(sockfd, message, message_len, na)) != message_len) {
// fprintf(stderr, "sendto error: %s\n", strerror(errno));
}
return result;
}
void listen_for_routers(int sockfd, int timeout, int networks_number, struct network_addr *networks, uint16_t *dists, list_t *dv) {
char buffer[IP_MAXPACKET + 1];
struct sockaddr_in sender;
while (poll_socket_modify_timeout(sockfd, &timeout)) {
recv_message(sockfd, buffer, &sender);
struct vector_item new_item = parse_message(buffer, &sender);
bool is_neighbour = false;
for (int i = 0; i < networks_number; i++) {
if (is_from_network(sender.sin_addr, networks[i])) {
is_neighbour = true;
break;
}
}
/* Shouldn't happen, just in case. */
if (!is_neighbour) {
char addr[20];
inet_ntop(AF_INET, &sender.sin_addr, addr, sizeof(addr));
fprintf(stderr, "Received datagram from %s, he is in none of my networks, ignoring\n. Maybe his VM routing table is configured incorrectly?\n", addr);
continue;
}
if (!is_from_network(sender.sin_addr, new_item.network)) {
new_item.is_connected_directly = false;
for (int i = 0; i < networks_number; i++) {
if (is_from_network(sender.sin_addr, networks[i])) {
new_item.distance += dists[i];
break;
}
}
}
update_dv_new_item(dv, new_item);
}
update_dv_reachability(dv);
}
void propagate_distance_vector(int sockfd, int networks_number, struct network_addr *networks, uint16_t *dists, list_t *dv) {
for (int i = 0; i < networks_number; i++) {
reset(dv);
while (dv->it != NULL) {
struct vector_item data = *(struct vector_item *)dv->it->data;
if (!(get_network_address(data.network).s_addr == get_network_address(networks[i]).s_addr) && data.reachable <= REACHABILITY_WAIT_TIME) {
_send_item(sockfd, networks[i], data);
}
iterate(dv);
}
struct vector_item self_item;
self_item.distance = dists[i];
self_item.network = networks[i];
_send_item(sockfd, networks[i], self_item);
}
}
bool is_from_network(struct in_addr ip_addr, struct network_addr network) {
struct network_addr temp;
temp.addr= ip_addr;
temp.netmask = network.netmask;
return (get_network_address(temp).s_addr == get_network_address(network).s_addr);
}
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