diff options
Diffstat (limited to 'Semestr 4/sieci/pracownia2/router.c')
| -rw-r--r-- | Semestr 4/sieci/pracownia2/router.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/Semestr 4/sieci/pracownia2/router.c b/Semestr 4/sieci/pracownia2/router.c new file mode 100644 index 0000000..79754b3 --- /dev/null +++ b/Semestr 4/sieci/pracownia2/router.c @@ -0,0 +1,212 @@ +#include <stdio.h> +#include <errno.h> +#include <strings.h> +#include <string.h> +#include <netinet/ip.h> +#include <arpa/inet.h> +#include <stdint.h> +#include <stdlib.h> +#include <poll.h> +#include <time.h> +#include <unistd.h> + +#define SERVER_PORT 54321 +#define TURN_LEN_S 5 +#define TURN_LEN_MS (1000 * TURN_LEN_S) +#define TURN_LEN_US (1000000 * TURN_LEN_S) +#define NS_TO_MS(X) ((long)(X) / (long)1000000) +#define S_TO_MS(X) ((long)(X) * (long)1000) + +struct router_addr { + struct in_addr addr; + uint16_t distance; + uint8_t netmask; +}; + +struct in_addr get_broadcast_address(struct router_addr ra) { + struct in_addr result = ra.addr; + /* bitshift by more than 31 is UB */ + if (ra.netmask < 32) { + result.s_addr |= ~((1<<ra.netmask) - 1); + } + return result; +} + +void pretty_print(struct router_addr ra) { + char ip_addr[20]; + inet_ntop(AF_INET, &ra.addr, ip_addr, sizeof(ip_addr)); + printf("%s/%d distance %d\n", ip_addr, ra.netmask, ra.distance); +} + +/* converts string of IP with netmask in CIDR notation to router_addr */ +struct router_addr stora(char *str) { + struct router_addr result; + char addr[20]; + size_t ip_preffix = strcspn(str, "/"); + + strncpy(addr, str, strlen(str)); + addr[ip_preffix] = 0; + inet_pton(AF_INET, addr, &(result.addr)); + result.netmask = atoi(str + ip_preffix + 1); + return result; +} + +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)); +} + +uint16_t read_configuration(struct router_addr** networks) { + uint16_t n; + scanf("%hd", &n); + *networks = malloc(n * sizeof(struct router_addr)); + for (int i = 0; i < n; i++) { + char addr[20]; + char _dist[10]; + uint16_t dist; + scanf(" %s %s %hd", addr, _dist, &dist); + (*networks)[i] = stora(addr); + (*networks)[i].distance = dist; + } + return n; +} + +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_modify_timeout(struct pollfd *fds, nfds_t nfd, int *timeout) { + if (*timeout < 0) { + fprintf(stderr, "poll_modify_timeout: timeout is negative.\n"); + exit(EXIT_FAILURE); + } + + struct timespec start; + clock_gettime(CLOCK_REALTIME, &start); + int result = poll(fds, nfd, *timeout); + + if (result == -1) { + fprintf(stderr, "poll error: %s\n", strerror(errno)); + exit(EXIT_FAILURE); + } + if (result == 0) { + *timeout = 0; + return 0; + } + struct timespec finish; + clock_gettime(CLOCK_REALTIME, &finish); + *timeout -= get_time_interval(start, finish); + printf("Timeout: %dms, time waiting: %ldms.\n", *timeout, get_time_interval(start, finish)); + return result; +} + +/* For debug purposes only */ +void recv_and_print(int sockfd, int networks_number, struct router_addr *networks) { + struct sockaddr_in sender; + socklen_t sender_len = sizeof(sender); + uint8_t buffer[IP_MAXPACKET + 1]; + ssize_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); + } + for (int i = 0; i < networks_number; i++) { + if (networks[i].addr.s_addr == sender.sin_addr.s_addr) { + return; + } + } + + char sender_ip_str[20]; + inet_ntop(AF_INET, &(sender.sin_addr), sender_ip_str, sizeof(sender_ip_str)); + printf("Received UDP packet from IP address: %s, port %d\n", + sender_ip_str, ntohs(sender.sin_port)); + + buffer[datagram_len] = 0; + printf("%ld-byte message: +%s+\n", datagram_len, buffer); + +} + +void listen_for_routers(int sockfd, int timeout, int networks_number, struct router_addr *netowrks) { + printf("Listening for %dms.\n", timeout); + struct pollfd fds; + fds.fd = sockfd; + fds.events = POLLIN; + fds.revents = 0; + while (poll_modify_timeout(&fds, 1, &timeout)) { + printf("Poll returned, remaining timeout: %dms.\n", timeout); + recv_and_print(sockfd, networks_number, netowrks); + } + printf("Finished listening\n"); +} + +int send_distance_vector(int sockfd, 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; + + char* message = "Hello server! My name is S1\n"; + ssize_t message_len = strlen(message); + int result; + + char addr[20]; + inet_ntop(AF_INET, &network, addr, sizeof(addr)); + printf("Sending datagram to %s\n", addr); + if ((result = sendto(sockfd, message, message_len, 0, (struct sockaddr*) &network_address, sizeof(network_address))) != message_len) { + fprintf(stderr, "sendto error: %s\n", strerror(errno)); + // return EXIT_FAILURE; + } +} + +void propagate_distance_vector(int sockfd, int networks_number, struct router_addr *networks) { + printf("Propagating distance vector\n"); + for (int i = 0; i < networks_number; i++) { + struct in_addr broadcast_address = get_broadcast_address(networks[i]); + send_distance_vector(sockfd, broadcast_address); + } + printf("Distance vector propagated.\n"); +} + +void router_loop(int sockfd, int networks_number, struct router_addr *networks) { + printf("Starting the router loop...\n"); + for (;;) { + listen_for_routers(sockfd, TURN_LEN_MS, networks_number, networks); + propagate_distance_vector(sockfd, networks_number, networks); + } +} + +int main() { + struct router_addr* networks; + int n = read_configuration(&networks); + for (int i = 0; i < n; i++) { + pretty_print(networks[i]); + } + + int sockfd = get_socket(); + bind_to_port(sockfd, SERVER_PORT); + router_loop(sockfd, n, networks); + + close(sockfd); + free(networks); +}
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