C-IPC/client.c

#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/msg.h>
#include <sys/stat.h>
#include <unistd.h>

#include "commands.h"
#include "signal.h"

// Wanted a graceful exit so need to keep this in global state
static int client_queue_id_global = -1;
static int server_queue_id_global = -1;
static char client_id_global[COMMAND_LENGTH];
static pid_t heartbeat_pid = -1;
static pid_t input_pid = -1;

// Make a macro for this cause I'm not typing sizeof twice every time
#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);
  }
}

void cleanup_and_exit(int sig) {
  printf("\nLogging out... ");

  if (server_queue_id_global != -1) {
    msgbuf_t logout = {.mtype = Logout, .sender = ""};
    strncpy(logout.sender, client_id_global, COMMAND_LENGTH - 1);
    msgsnd(server_queue_id_global, &logout, sizeof(logout) - sizeof(long), 0);
  }

  // Burn the orphanage
  if (heartbeat_pid > 0)
    kill(heartbeat_pid, SIGTERM);
  if (input_pid > 0)
    kill(input_pid, SIGTERM);

  cleanup_queue(client_queue_id_global);

  printf("Bye!\n");
  exit(0);
}

static void input_loop(int server_queue_id, const char *client_id) {
  while (1) {
    // Minimum length plus extra space fore command name and seperators
    // I'd prefer some more space than required to not have to worry about cutoffs
    char buffer[COMMAND_LENGTH + MESSAGE_LENGTH + 64];
    if (fgets(buffer, sizeof(buffer), stdin) == NULL) {
      break;
    }

    buffer[strcspn(buffer, "\n")] = '\0';

    if (strncmp(buffer, "/msg ", 5) == 0) {
      char *space_ptr = strchr(buffer + 5, ' ');
      if (space_ptr == NULL) {
        printf("Invalid /msg format. Use /msg <nickname> or #<groupname> <message>\n");
        continue;
      }

      char target[COMMAND_LENGTH];
      size_t target_len = space_ptr - (buffer + 5);

      if (target_len == 0 || target_len >= COMMAND_LENGTH) {
        printf("Invalid target length\n");
        continue;
      }

      strncpy(target, buffer + 5, target_len); // Copy everything including '#' if present
      target[target_len] = '\0';

      char *message = space_ptr + 1;
      if (strlen(message) == 0) {
        printf("Message cannot be empty\n");
        continue;
      }

      msgbuf_t msg = {.mtype = Message, .sender = ""};
      strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
      strncpy(msg.command, target, COMMAND_LENGTH - 1); // Send as-is (with '#' if group)
      strncpy(msg.message, message, MESSAGE_LENGTH - 1);
      if (send(server_queue_id, &msg) == -1) {
        perror("msgsnd(/msg) failed");
      }
    } else if (strncmp(buffer, "/list ", 6) == 0) {
      char *offset = buffer + 6;

      if (strcmp(offset, "active") != 0 && strcmp(offset, "all") != 0 && strcmp(offset, "groups") != 0) {
        printf("Invalid list type. Use /list active or /list all or /list groups\n");
        continue;
      }

      msgbuf_t msg = {.mtype = List, .sender = ""};
      strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
      strncpy(msg.command, offset, COMMAND_LENGTH - 1);
      if (send(server_queue_id, &msg) == -1) {
        perror("msgsnd(/list) failed");
      }
    } else if (strncmp(buffer, "/join ", 6) == 0) {
      char *group_name = buffer + 6;
      if (strlen(group_name) == 0) {
        printf("Group name cannot be empty\n");
        continue;
      }

      msgbuf_t msg = {.mtype = JoinGroup, .sender = ""};
      strncpy(msg.sender, client_id, COMMAND_LENGTH);
      strncpy(msg.command, group_name, COMMAND_LENGTH - 1);
      if (send(server_queue_id, &msg) == -1) {
        perror("msgsnd(/join) failed");
      }
    } else if (strncmp(buffer, "/leave ", 7) == 0) {
      char *group_name = buffer + 7;
      if (strlen(group_name) == 0) {
        printf("Group name cannot be empty\n");
        continue;
      }

      msgbuf_t msg = {.mtype = LeaveGroup, .sender = ""};
      strncpy(msg.sender, client_id, COMMAND_LENGTH);
      strncpy(msg.command, group_name, COMMAND_LENGTH - 1);
      if (send(server_queue_id, &msg) == -1) {
        perror("msgsnd(/leave) failed");
      }
    } else if (strncmp(buffer, "/mute ", 6) == 0) {
      char *nickname = buffer + 6;
      if (strlen(nickname) == 0) {
        printf("Nickname cannot be empty\n");
        continue;
      }

      msgbuf_t msg = {.mtype = Mute, .sender = ""};
      strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
      strncpy(msg.command, nickname, COMMAND_LENGTH - 1);
      if (send(server_queue_id, &msg) == -1) {
        perror("msgsnd(/mute) failed");
      }
    } else if (strncmp(buffer, "/unmute ", 8) == 0) {
      char *nickname = buffer + 8;
      if (strlen(nickname) == 0) {
        printf("Nickname cannot be empty\n");
        continue;
      }

      msgbuf_t msg = {.mtype = Unmute, .sender = ""};
      strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
      strncpy(msg.command, nickname, COMMAND_LENGTH - 1);
      if (send(server_queue_id, &msg) == -1) {
        perror("msgsnd(/unmute) failed");
      }
    } else if (strcmp(buffer, "/quit") == 0 || strcmp(buffer, "/exit") == 0 || strcmp(buffer, "/q") == 0) {
      return;
    } else if (strncmp(buffer, "/inbox", 8) == 0) {
      msgbuf_t msg = {.mtype = Inbox, .sender = ""};
      strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
      if (send(server_queue_id, &msg) == -1) {
        perror("msgsnd(/mailbox) failed");
      }
    } else {
      printf("Unknown command\n");
    }
  }
}

int main(int argc, char *argv[]) {
  if (argc < 2) {
    fprintf(stderr, "Usage: %s <client_id>\n", argv[0]);
    return 1;
  }

  char *client_id = argv[1];

  int client_queue_id = msgget(IPC_PRIVATE, IPC_CREAT | 0666);
  if (client_queue_id == -1) {
    perror("msgget(client) failed");
    return 1;
  }

  int server_queue_id = -1;
  const char *id_path = "server_queue_id";
  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 (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;
  }
  close(fd);

  msgbuf_t msg = {.mtype = Login, .sender = ""};
  strncpy(msg.sender, client_id, COMMAND_LENGTH - 1);
  snprintf(msg.command, COMMAND_LENGTH, "%d", client_queue_id);

  if (msgsnd(server_queue_id, &msg, sizeof(msg) - sizeof(long), 0) == -1) {
    perror("msgsnd(login) failed");
    cleanup_queue(client_queue_id);
    return 1;
  }

  /* Wait for login response (server replies with mtype = Login) */
  msgbuf_t resp;
  ssize_t r = msgrcv(client_queue_id, &resp, sizeof(resp) - sizeof(long), Login, 0);
  if (r == -1) {
    perror("msgrcv(login response) failed");
    cleanup_queue(client_queue_id);
    return 1;
  }

  if (resp.stype == ERR_ALREADY_LOGGED_IN) {
    fprintf(stderr, "Login failed: User already logged in\n");
    cleanup_queue(client_queue_id);
    return 1;
  } else if (resp.stype == ERR_NOT_FOUND) {
    fprintf(stderr, "Login failed: User not found\n");
    cleanup_queue(client_queue_id);
    return 1;
  }

  printf("Login accepted. Welcome, %s!\n", resp.command);

  strncpy(client_id_global, client_id, COMMAND_LENGTH - 1);
  client_queue_id_global = client_queue_id;
  server_queue_id_global = server_queue_id;

  heartbeat_pid = fork();
  if (heartbeat_pid == 0) {
    heartbeat_loop(server_queue_id, client_id);
    return 0;
  }

  input_pid = fork();
  if (input_pid == 0) {
    input_loop(server_queue_id, client_id);
    // The /quit command just returns from the input loop
    kill(getppid(), SIGTERM);
    return 0;
  }

  // Setup them below the forks to avoid multiple triggers
  signal(SIGINT, cleanup_and_exit);
  signal(SIGTERM, cleanup_and_exit);

  while (1) {
    msgbuf_t incoming;
    ssize_t got = msgrcv(client_queue_id, &incoming, sizeof(incoming) - sizeof(long), 0, 0);
    if (got == -1) {
      perror("msgrcv(incoming) failed");

      if (errno == EINTR) {
        continue;
      }
      perror("msgrcv(incoming) failed");
      break;
    }

    switch (incoming.mtype) {
    case Message: {
      printf("%s: %s\n", incoming.sender, incoming.message);
      msgbuf_t ack = {.mtype = Signal, .stype = ACK_DELIVERED, .command = ""};
      strncpy(ack.command, incoming.command, COMMAND_LENGTH);
      send(server_queue_id, &ack);
      break;
    }
    case List: {
      // Check the command field for the list type
      if (strncmp(incoming.command, "active", COMMAND_LENGTH) == 0) {
        printf("Active clients:\n%s\n", incoming.message);
      } else if (strncmp(incoming.command, "groups", COMMAND_LENGTH) == 0) {
        printf("All group members:\n%s\n", incoming.message);
      } else {
        printf("All clients:\n%s\n", incoming.message);
      }
      break;
    }
    case Inbox: {
      // Upon recieving an inbox message, check the command field for the index
      // Index of -1 means that there are no messages in the mailbox
      if (strcmp(incoming.command, "-1") == 0) {
        printf("Your inbox is empty.\n");
        break;
      }

      // Index of 0 means that there are messages in the mailbox
      if (strcmp(incoming.command, "0") == 0) {
        printf("You have messages in your box!\n");
        continue;
      }

      // Index of 1 is just the first message so print a header
      if (strcmp(incoming.command, "1") == 0) {
        printf("Your inbox messages:\n");
      }
      printf("[%s] %s: %s\n", incoming.command, incoming.sender, incoming.message);
      break;
    }
    case Signal:
      // Tell the user if the previous message was accepted and/or delivered
      if (incoming.stype == ACK_ACCEPTED) {
        printf("[Sent]\n");
      } else if (incoming.stype == ACK_DELIVERED) {
        printf("[Delivered: %s]\n", incoming.sender);
      } else if (incoming.stype == ERR_NOT_FOUND) {
        printf("[Error: User not found]\n");
      } else {
        // Display whatever if I forgot to handle something
        printf("[Error: Code %d]\n", incoming.stype);
      }
      break;
    case JoinGroup:
      if (incoming.stype == ACK_ACCEPTED) {
        printf("Successfully joined the group.\n");
      } else if (incoming.stype == ERR_NOT_FOUND) {
        printf("Group does not exist.\n");
      } else if (incoming.stype == ERR_ALREADY_IN_GROUP) {
        printf("You are already in this group.\n");
      } else {
        printf("Failed to join group: Unknown error (code %d).\n", incoming.stype);
      }
      break;
    case LeaveGroup:
      if (incoming.stype == ACK_ACCEPTED) {
        printf("Successfully left the group.\n");
      } else if (incoming.stype == ERR_NOT_FOUND) {
        printf("Group does not exist.\n");
      } else {
        printf("Failed to leave group: Unknown error (code %d).\n", incoming.stype);
      }
      break;
    case Mute:
      if (incoming.stype == ACK_ACCEPTED) {
        printf("Successfully muted %s.\n", incoming.command);
      } else if (incoming.stype == ERR_NOT_FOUND) {
        printf("%s not found.\n", incoming.command);
      } else if (incoming.stype == ERR_ALREADY_IN_GROUP) {
        printf("%s is already muted.\n", incoming.command);
      } else {
        printf("Failed to mute: Unknown error (code %d).\n", incoming.stype);
      }
      break;
    case Unmute:
      if (incoming.stype == ACK_ACCEPTED) {
        printf("Successfully unmuted %s.\n", incoming.command);
      } else if (incoming.stype == ERR_NOT_FOUND) {
        printf("%s wasn't muted.\n", incoming.command);
      } else {
        printf("Failed to unmute: Unknown error (code %d).\n", incoming.stype);
      }
      break;
    default:
      printf("Received unknown command of mtype=%ld stype=%d\n", (long)incoming.mtype, incoming.stype);
      break;
    }
  }

  cleanup_queue(client_queue_id);
  return 0;
}