Updated tomd and tomc to do solid communication over sockets.

[tlb/tomd.git] / src / tomd / main.c

/* Copyright (C) 2018 Thomas Balzer */

/* This file is part of tomd. */

/* tomd is free software: you can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation, either version 3 of the License, or */
/* (at your option) any later version. */

/* tomd is distributed in the hope that it will be useful, */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the */
/* GNU General Public License for more details. */

/* You should have received a copy of the GNU General Public License */
/* along with tomd.  If not, see <http://www.gnu.org/licenses/>. */

#include <stddef.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/un.h>
#include <sys/stat.h>
#include <sys/socket.h>

#include "../../include/macros.h"
#include "../../include/manifest.h"

static void header(void)
{
  tomd_p("Tom's Daemon, Copyright (C) 2018 Thomas Balzer");
  tomd_p("GPL v3 or later license.");
}

static int sfd;
static char socket_dirname[100];
static char socket_filename[100];

static void gen_socket_filename(void)
{
  uid_t this_user_id =
    getuid();
  sprintf(socket_dirname,
          "/run/user/%d/tomd",
          this_user_id);
  sprintf(socket_filename,
          "/run/user/%d/tomd/socket",
          this_user_id);

  tomd_p("making dir '%s'", socket_dirname);
  /* lazy way */
  char buf[100];
  sprintf(buf, "mkdir -p %s", socket_dirname);
  system(buf);
  /* if(mkdir(socket_dirname, S_IRWXU) != 0){ */
  /*   perror("socket mkdir"); */
  /*   exit(EXIT_FAILURE); */
  /* } */

  tomd_p("removing file '%s'", socket_filename);
  if(unlink(socket_filename) != 0){
    if(errno == ENOENT){
      tomd_p("socket file doesn't exist");
    }else{
      perror("[tomd] socket unlink");
      exit(EXIT_FAILURE);
    }
  }
}

static void socket_init(void)
{
  gen_socket_filename();
  
  /* listen on socket, respond to requests. */
  /* perform all registered 'tick' operations */
  sfd =
    socket(PF_LOCAL,         /* namespace - local unix socket */
           SOCK_STREAM,      /* style */
           0);               /* protocol */

  if(sfd < 0){
    perror("[tomd] socket");
    exit(EXIT_FAILURE);
  }

  struct sockaddr_un name;
  size_t size;

  name.sun_family = AF_LOCAL;
  strncpy(name.sun_path,
          socket_filename,
          sizeof(name.sun_path));

  size = SUN_LEN(&name);
  tomd_p("attempting to bind to '%s'",
         socket_filename);
  if(bind(sfd,
          (struct sockaddr *) &name,
          size) < 0){
    perror("[tomd] bind");
    exit(EXIT_FAILURE);
  }

  tomd_p("initialized tomd socket connections");
}

static void init(void)
{
  socket_init();
  load_jobs();
}

#define SEND_ACK {                                                      \
    int size;                                                           \
    if(size = write(asfd, "ACK", sizeof "ACK") != sizeof "ACK") {       \
      tomd_p("didn't send as much as we though (%d != %d)", size, sizeof "ACK"); \
    }                                                                   \
  }

#define CHDIR            0
#define DONT_CHDIR       1
#define CLOSE_PIPES      0
#define DONT_CLOSE_PIPES 1

static void daemonize(void)
{
  /* daemon is in unistd. */
  /* arg1 - 0 changes dir to / */
  /* arg2 - 0 closes all pipes (/dev/null) */
  /* WARNING > THIS BEHAVIOR IS SILENT AND EASY TO MISPLACE THE
     PROCESS  */
  daemon(DONT_CHDIR, DONT_CLOSE_PIPES);
}

#define READ_SOCKET {\
    int size = read(asfd, buf, 100);            \
    buf[size] = '\0';                           \
  }

static int validate_sender(int asfd, char *buf)
{
  READ_SOCKET;
  if(strcmp(buf, "client:tomc") == 0){
    SEND_ACK;
    return 0;
  }
  tomd_p("received '%s' instead of client:tomc", buf);
  return -1;
}

enum requests { KILL, STATUS, STOP, START, UNKNOWN};
#define X(a, b) { a, b }
static struct {
  char *str;
  enum requests request;
} request_types[] =
  {
   X("kill", KILL),
   X("status", STATUS),
   X("start", START),
   X("stop", STOP),
   X(NULL, -1)
  };
#undef X

static void handle_request(int asfd, char *buf)
{
  READ_SOCKET;
  enum requests request = UNKNOWN;
  int i = 0;
  while(1){
    if(request_types[i].str == NULL){
      break;
    }

    tomd_p("loop [%d]: comparing '%s' to '%s'",
           i, buf, request_types[i].str);
    if(strcmp(buf, request_types[i].str) == 0){
      request = request_types[i].request;
      break;
    }
    
    i++;
  }

  if(request == UNKNOWN){
    tomd_p("unknown request type!");
    return;
  }

  SEND_ACK;
  READ_SOCKET;
  // cross reference given name against known services
  tomd_p("looking up '%s'", buf);
  SEND_ACK;
  /* lookup_job(buf); */
}

static void handle_connection(int asfd)
{
  char buf[100] = {};

  if(validate_sender(asfd, buf) != 0){
    tomd_p("invalid sender.");
    return;
  }

  tomd_p("validated client");
  handle_request(asfd, buf);

  close(asfd);
}

static void run(void)
{
  /* loop: */
  /*  1 listen */
  /*  2 accept/select */
  /*  3 handle dgram */
  int listen_bool =
    listen(sfd,
           10); /* max connection limit is 10 for arbitrary reasons */
  if(listen_bool == -1){
    perror("[tomd] listen");
    exit(EXIT_FAILURE);
  }

  int i = 0;
  for(;;){
    struct sockaddr addr;
    /* sometimes gives EINVAL if not initialized. */
    socklen_t size = sizeof(addr);
    tomd_p("accept loop [%d]", i++);
    errno = 0;
    int accept_sfd =
      accept(sfd,
             &addr,             /* requester info */
             &size);            /* len of requester info */
    if(accept_sfd < 0){
      if(errno == EINVAL){
        tomd_p("EINVAL");
      }
      perror("[tomd] accept socket");
      exit(EXIT_FAILURE);
    }
    
    handle_connection(accept_sfd);
  }
}

static void cleanup(void)
{
  if(sfd >= 0){
    close(sfd);
  }
}

int main(int argc, char **argv)
{
  header();
  init();
  run_jobs();
  daemonize();
  run();
  cleanup();
  
  return EXIT_SUCCESS;
}