Implemented hearbeat

client.c

@@ -1,16 +1,28 @@
-#include "commands.h"
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 #include <sys/msg.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
+#include "commands.h"
+
 #define send(queue_id, msgbuf_ptr)                                             \
   msgsnd(queue_id, msgbuf_ptr, sizeof(*(msgbuf_ptr)) - sizeof(long), 0)
 
+static void heartbeat_loop(int server_queue_id, const char *client_id) {
+  msgbuf_t msg = {.mtype = Hearbeat, .sender = ""};
+  strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
+  while (1) {
+    if (send(server_queue_id, &msg) == -1) {
+      perror("msgsnd(heartbeat) failed");
+      break;
+    }
+    sleep(HEARTBEAT_INTERVAL);
+  }
+}
+
 static void cleanup_queue(int qid) {
   if (qid != -1) {
     msgctl(qid, IPC_RMID, NULL);
@@ -33,21 +45,22 @@ int main(int argc, char *argv[]) {
 
   int server_queue_id = -1;
   const char *id_path = "/home/piotr/server_queue_id";
-  FILE *f = fopen(id_path, "rb");
+  int fd = open(id_path, O_RDONLY);
+  if (fd == -1) {
+    perror("Failed to open server queue id file");
+    cleanup_queue(client_queue_id);
+    return 1;
+  }
 
-  if (fread(&server_queue_id, sizeof(int), 1, f) != 1) {
+  if (read(fd, &server_queue_id, sizeof(int)) == -1) {
     fprintf(stderr, "Failed to read server queue id from %s\n", id_path);
     server_queue_id = -1;
   }
-  fclose(f);
+  close(fd);
 
-  msgbuf_t msg;
+  msgbuf_t msg = {.mtype = Login, .sender = ""};
-  memset(&msg, 0, sizeof(msgbuf_t));
+  strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
-  msg.mtype = Login;
+  snprintf(msg.command, COMMAND_LENGTH, "%d", client_queue_id);
-  /* command field holds client id for login */
-  strncpy(msg.command, client_id, COMMAND_LENGTH - 1);
-  /* message field holds the client's queue id as string */
-  snprintf(msg.message, MESSAGE_LENGTH, "%d", client_queue_id);
 
   if (msgsnd(server_queue_id, &msg, sizeof(msg) - sizeof(long), 0) == -1) {
     perror("msgsnd(login) failed");
@@ -73,11 +86,14 @@ int main(int argc, char *argv[]) {
 
   printf("Login accepted for id '%s'\n", client_id);
 
+  if (fork() == 0) {
+    heartbeat_loop(server_queue_id, client_id);
+    return 0;
+  }
+
   /* Send a test message to the server */
-  msgbuf_t test = {
+  msgbuf_t test = {.mtype = Message, .sender = ""};
-      .mtype = Message,
+  strncpy(test.sender, client_id, COMMAND_LENGTH - 1);
-      .sender = "the_only_one",
-  };
   snprintf(test.message, MESSAGE_LENGTH, "Hello from %s", client_id);
 
   if (msgsnd(server_queue_id, &test, sizeof(test) - sizeof(long), 0) == -1) {
@@ -90,7 +106,8 @@ int main(int argc, char *argv[]) {
   printf("Sent test message to server: \"%s\"\n", test.message);
 
   /* Now wait for server forwarded message(s) and a signal ack.
-     We'll wait until we've seen both a Message and a Signal ack or timeout. */
+     We'll wait until we've seen both a Message and a Signal ack or timeout.
+   */
   int seen_message = 0;
   int seen_ack = 0;
   const int MAX_ITER = 10;

commands.h

@@ -1,6 +1,9 @@
 #define MESSAGE_LENGTH 256
 #define COMMAND_LENGTH 16
 
+#define HEARTBEAT_INTERVAL 3 // in seconds
+#define HEARTBEAT_TIMEOUT 10
+
 typedef enum {
   Message = 1,
   Login,

server.c

@@ -1,14 +1,19 @@
-#include "commands.h"
+#include "bits/types/struct_timeval.h"
 #include "sys/ipc.h"
+#include "sys/shm.h"
 #include <fcntl.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/msg.h>
+#include <sys/sem.h>
+#include <sys/time.h>
 #include <sys/types.h>
 #include <unistd.h>
 
+#include "commands.h"
+
 #define send(queue_id, msgbuf_ptr)                                             \
   msgsnd(queue_id, msgbuf_ptr, sizeof(*(msgbuf_ptr)) - sizeof(long), 0)
 
@@ -18,6 +23,7 @@ typedef struct {
   char *muted_clients;
   char nickname[16];
   int queue_id;
+  long last_seen;
 } Client;
 
 typedef struct {
@@ -26,21 +32,56 @@ typedef struct {
   int client_count;
 } Group;
 
+static void handle_hearbeat_timeouts(Client *clients, int client_count,
+                                     int semaphore_id) {
+  struct sembuf sem_op = {
+      .sem_num = 0,
+      .sem_op = 1,
+      .sem_flg = 0,
+  };
+  while (1) {
+    sem_op.sem_op = 1;
+    semop(semaphore_id, &sem_op, 1);
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    for (int i = 0; i < client_count; i++) {
+      if (clients[i].logged_in &&
+          (tv.tv_sec - clients[i].last_seen) > HEARTBEAT_TIMEOUT) {
+        printf("Client %s has timed out due to missed heartbeats\n",
+               clients[i].id);
+        clients[i].logged_in = false;
+        clients[i].queue_id = -1;
+      }
+    }
+    sem_op.sem_op = -1;
+    semop(semaphore_id, &sem_op, 1);
+    sleep(HEARTBEAT_TIMEOUT);
+  }
+}
+
 int main(int argc, char **argv) {
   // TODO: Load config file with clients and groups
-  int client_count = 1;
+  int client_count = 2;
   int group_count = 3;
-  Client *clients = malloc(sizeof(Client) * 9);
+  int clients_memory_id =
+      shmget(IPC_PRIVATE, sizeof(Client) * client_count, IPC_CREAT | 0666);
+  Client *clients = shmat(clients_memory_id, NULL, 0);
   Group *groups = malloc(sizeof(Group) * 3);
 
-  clients[0] = (Client){
+  int semaphore_id = semget(IPC_PRIVATE, 1, IPC_CREAT | 0666);
-      .id = "the_only_one",
+  semctl(semaphore_id, 0, SETVAL, 1);
+
+  clients[0] = (Client){.id = "test1",
                         .logged_in = false,
                         .muted_clients = NULL,
                         .nickname = "Kregielnia",
-  };
+                        .last_seen = 0};
+  clients[1] = (Client){.id = "test2",
+                        .logged_in = false,
+                        .muted_clients = NULL,
+                        .nickname = "Bajzel",
+                        .last_seen = 0};
 
-  // key_t key = ftok(argv[0], 555);
   int server_queue_id = msgget(IPC_PRIVATE, 0666 | IPC_CREAT);
 
   if (server_queue_id == -1) {
@@ -61,7 +102,11 @@ int main(int argc, char **argv) {
   }
   close(id_file_handle);
 
-  // TODO: Fork here, for the heartbeat process than can sleep
+  if (fork() == 0) {
+    handle_hearbeat_timeouts(clients, client_count, semaphore_id);
+    return 0;
+  }
+
   msgbuf_t msgbuf;
   while (1) {
     // Read from the ipc, then handle the command
@@ -70,19 +115,19 @@ int main(int argc, char **argv) {
 
     switch (msgbuf.mtype) {
     case Login:
-      printf("Received login request for id: %s\n", msgbuf.command);
+      printf("Received login request for id: %s\n", msgbuf.sender);
       Client *client = NULL;
       for (int i = 0; i < 1; i++) {
-        if (strncmp(clients[i].id, msgbuf.command, COMMAND_LENGTH) == 0) {
+        if (strncmp(clients[i].id, msgbuf.sender, COMMAND_LENGTH) == 0) {
           client = &clients[i];
           break;
         }
       }
 
       // Reuse the buffer to get the client's message queue id
-      int msg_queue_id = atoi(msgbuf.message);
+      int msg_queue_id = atoi(msgbuf.command);
       if (client == NULL) {
-        printf("User not found: %s\n", msgbuf.command);
+        printf("User not found: %s\n", msgbuf.sender);
         msgbuf_t response = {
             .mtype = Login,
             .stype = ERR_USER_NOT_FOUND,
@@ -93,7 +138,7 @@ int main(int argc, char **argv) {
       }
 
       if (client->logged_in) {
-        printf("User already logged in: %s\n", msgbuf.command);
+        printf("User already logged in: %s\n", msgbuf.sender);
         msgbuf_t response = {
             .mtype = Login,
             .stype = ERR_ALREADY_LOGGED_IN,
@@ -105,15 +150,17 @@ int main(int argc, char **argv) {
 
       client->logged_in = true;
       client->queue_id = msg_queue_id;
+      struct timeval tv;
+      gettimeofday(&tv, NULL);
+      client->last_seen = tv.tv_sec;
       msgbuf_t response = {
           .mtype = Login,
           .stype = ACK_ACCEPTED,
       };
-      printf("User accepted: %s\n", msgbuf.command);
+      printf("User accepted: %s\n", msgbuf.sender);
       send(msg_queue_id, &response);
       break;
     case Message:
-
       printf("Recieved message, checking which client\n");
       // Find the client that sent the message then forward it to all the
       // specified recipients
@@ -161,6 +208,26 @@ int main(int argc, char **argv) {
       break;
     case Logout:
     case Hearbeat:
+      for (int i = 0; i < client_count; i++) {
+        if (strncmp(clients[i].id, msgbuf.sender, COMMAND_LENGTH) == 0 &&
+            clients[i].logged_in) {
+          // Take the semaphore to update last_seen
+          struct sembuf sem_op = {
+              .sem_num = 0,
+              .sem_op = -1,
+              .sem_flg = 0,
+          };
+          semop(semaphore_id, &sem_op, 1);
+          struct timeval tv;
+          gettimeofday(&tv, NULL);
+          clients[i].last_seen = tv.tv_sec;
+
+          // Free the semaphore
+          sem_op.sem_op = 1;
+          semop(semaphore_id, &sem_op, 1);
+        }
+      }
+      break;
     case List_clients:
       break;
     case Mute: