Socket communication fixes

lib/helpers.c

@@ -35,7 +35,7 @@ void enable_echo_broadcast(void) {
  * Function based on this snippet:
  * https://codereview.stackexchange.com/a/58107
 */
-void search_for_neighbors(void) {
+void search_for_neighbors(node_handle_t **neighbors, uint16_t *num_neighbors, uint16_t port) {
 	// Broadcasts ping
 	if (system("ping -b 10.255.255.255 -c 3 > /dev/null") < 0) {
 		perror("Couldn't broadcast echo.");
@@ -58,14 +58,94 @@ void search_for_neighbors(void) {
 
 	// Extracts IP addresses found in the file
 	char ipAddr[ARP_BUFFER_LEN];
+	char **neighbors_ips = (char **) malloc(sizeof(char *));
+	if (!neighbors_ips) {
+		perror("Unable to allocate memory for neighbor IP.");
+		exit(EXIT_FAILURE);
+	}
+
 	int count = 0;
 	while (1 == fscanf(arpCache, ARP_LINE_FORMAT, ipAddr)) {
-		printf("%03d: [%s]\n", ++count, ipAddr);
+		++count;
+		if (count > 1){
+			char **r_neighbors_ips = realloc(neighbors_ips, count * sizeof(char *));
+			if (!r_neighbors_ips) {
+				free(r_neighbors_ips);
+				perror("Unable to reallocate memory for neighbor IP.");
+				exit(EXIT_FAILURE);
+			}
+
+			neighbors_ips = r_neighbors_ips;
+		}
+
+		neighbors_ips[count - 1] = (char *) malloc(ARP_BUFFER_LEN * sizeof(char));
+		strcpy(neighbors_ips[count - 1], ipAddr);
+	}
+
+	// Allocates memory for the new neighbors structs
+	if (!(*num_neighbors)) {
+		// Neighbors array came empty
+		(*neighbors) = (node_handle_t *) malloc(count * sizeof(node_handle_t));
+		if (!neighbors_ips) {
+			perror("Unable to allocate memory for nodes.");
+			exit(EXIT_FAILURE);
+		}
+	} else {
+		node_handle_t *r_neighbors = realloc((*neighbors), count * sizeof(node_handle_t));
+		if (!r_neighbors) {
+			free(r_neighbors);
+			perror("Unable to reallocate memory for nodes.");
+			exit(EXIT_FAILURE);
+		}
+
+		(*neighbors) = r_neighbors;
+	}
+
+	// Adds new event timestamps to neighbors structs
+	for (uint8_t i = 0; i < count; ++i) {
+		bool found_flag = false;
+
+		for (uint8_t j = 0; j < (*num_neighbors); ++j) {
+			if (!strcmp(inet_ntoa(node_get_addr((*neighbors)[j]).sin_addr),
+				neighbors_ips[i])) {
+				bool node_alive = check_node_alive(neighbors_ips[i]);
+				node_add_timestamp((*neighbors)[i], time(NULL), node_alive);
+
+				found_flag = true;
+				break;
+			}
+		}
+
+		if (!found_flag) {
+			// New node found!
+			printf("Adding %s\n", neighbors_ips[i]);
+			struct sockaddr_in peer_name;
+			init_sockaddr(&peer_name, neighbors_ips[i], port);
+			(*neighbors)[(*num_neighbors)++] = node_init(peer_name);
+		}
+	}
+
+	if (!((*num_neighbors) == count)) {
+		(*num_neighbors) = count;
 	}
 
 	fclose(arpCache);
 }
 
+bool check_node_alive(const char *ipv4) {
+	char command[64];
+
+	snprintf(command, 64, "ping %s -c 1 -W 1 | grep \"1 received\" > /dev/null", ipv4);
+
+	int call_res = system(command);
+	if (call_res < 0) {
+		perror("Couldn't ping node.");
+		exit(EXIT_FAILURE);
+	}
+
+	return call_res == 0;
+}
+
 /*
  * Function based on this example:
  * https://www.gnu.org/software/libc/manual/html_node/Inet-Example.html#Inet-Example
@@ -100,9 +180,8 @@ int create_socket_and_listen(uint16_t port, uint8_t backlog_size) {
 	return in_sock;
 }
 
-void send_message(const char *ipv4, uint16_t port, const char *message) {
+void send_message(struct sockaddr_in peer_name, const char *message) {
 	int out_sock;
-	struct sockaddr_in peer_name;
 
 	// Creates the socket
 	out_sock = socket(PF_INET, SOCK_STREAM, 0);
@@ -112,7 +191,6 @@ void send_message(const char *ipv4, uint16_t port, const char *message) {
 	}
 
 	// Connects to the peer
-	init_sockaddr(&peer_name, ipv4, port);
 	if (connect(out_sock, (struct sockaddr *) &peer_name, sizeof(peer_name))) {
 		printf("Couldn't connect to the peer.\n");
 	} else {

lib/helpers.h

@@ -14,6 +14,9 @@
 #include <sys/time.h>
 #include <signal.h>
 #include <string.h>
+#include <sys/wait.h>
+
+#include "node.h"
 
 // Macros to turn a numeric macro into a string literal
 #define xstr(s) str(s)
@@ -23,6 +26,7 @@
 #define ARP_CACHE "/proc/net/arp"
 #define ARP_STRING_LEN 1023
 #define ARP_BUFFER_LEN (ARP_STRING_LEN + 1)
+#define PING_BUFFER_LEN 1024
 
 // Format for fscanf() to read the 1st field of ARP
 #define ARP_LINE_FORMAT "%" xstr(ARP_STRING_LEN) "s %*s %*s %*s %*s %*s"
@@ -31,11 +35,13 @@ void set_timer_and_handler(void (*handler)(int), long int timer_interval);
 
 void enable_echo_broadcast(void);
 
-void search_for_neighbors(void);
+void search_for_neighbors(node_handle_t **neighbors, uint16_t *num_neighbors, uint16_t port);
+
+bool check_node_alive(const char *ipv4);
 
 int create_socket_and_listen(uint16_t port, uint8_t backlog_size);
 
-void send_message(const char *ipv4, uint16_t port, const char *message);
+void send_message(struct sockaddr_in peer_name, const char *message);
 
 void accept_connection(int sock, struct sockaddr_in *client_name, fd_set *active_fd_set);
 

lib/node.c

@@ -5,8 +5,6 @@
 
 #include "node.h"
 
-//enum node_status { NODE_INITIALIAZED, NODE_PRESENT, NODE_GONE };
-
 // Defines the node structure
 struct node_t {
 	struct sockaddr_in addr;

src/zaqar.c

@@ -8,13 +8,17 @@ int main(void) {
 	int in_sock;
 	fd_set active_fd_set, read_fd_set;
 	struct sockaddr_in peer_name;
+	node_handle_t *neighbors;
+	uint16_t num_neighbors = 0;
 
-	// Sets a timer and handler to produce interrupts for sending messages
-	set_timer_and_handler(handle_alarm, TIMER_INTERVAL);
+	// Enables echo broadcast pings
+	enable_echo_broadcast();
 
 	// Searches network for neighbors
-	enable_echo_broadcast();
-	search_for_neighbors();
+	search_for_neighbors(&neighbors, &num_neighbors, PORT);
+
+	// Sets a timer and handler to produce interrupts for sending messages
+	set_timer_and_handler(handle_alarm, TIMER_INTERVAL);
 
 	// Creates a socket and sets it up to accept connections
 	in_sock = create_socket_and_listen(PORT, BACKLOG_SIZE);
@@ -28,7 +32,14 @@ int main(void) {
 	while (1) {
 		if (sigalrm_flag) {
 			// It's time to send a message!
-			send_message("10.0.82.61", PORT, MESSAGE);
+
+			search_for_neighbors(&neighbors, &num_neighbors, PORT);
+
+			for (uint8_t i = 0; i < num_neighbors; ++i) {
+				if (node_get_status(neighbors[i]) == NODE_PRESENT) {
+					send_message(node_get_addr(neighbors[i]), MESSAGE);
+				}
+			}
 
 			sigalrm_flag = false;
 		}

src/zaqar.h

@@ -16,6 +16,7 @@
 #include <sys/signalfd.h>
 
 #include "helpers.h"
+#include "node.h"
 
 #define TIMER_INTERVAL 10
 #define PORT 5000