/*
 * logclean.c by CoKi <coki@nosystem.com.ar>
 *
 * This tool cleans WTMP, UTMP and lastlog for linux
 *
 * No System Group - http://www.nosystem.com.ar
 *
 */

#include <stdio.h>
#include <string.h>
#include <utmp.h>
#include <getopt.h>
#include <lastlog.h>
#include <pwd.h>

#define VERSION "0.1"

int uwtmp_clean(char *path, char *user);
int lastlog_clean(char *path, char *user);
void use(char *program);
void version(void);

int main(int argc, char *argv[]) {
  char user[UT_LINESIZE];
  char c;

  while((c = getopt(argc, argv, "vu:")) != EOF) {
    switch(c) {
      case 'v':
        version();
              break;
      case 'u':
        if(strlen(optarg) > UT_LINESIZE) {
          printf("user name too long\n");
          exit(0);
        }
        snprintf(user, sizeof(user), "%s", optarg);
        break;
      default :
        use(argv[0]);
        break;
    }
  }

  if(user == NULL || argc < 2) {
    use(argv[0]);
  }

  printf(" UTMP:\t\t");
  fflush(stdout);
  uwtmp_clean(_PATH_UTMP, user);

  printf(" WTMP:\t\t");
  fflush(stdout);
  uwtmp_clean(_PATH_WTMP, user);

  printf(" LASTLOG:\t");
  fflush(stdout);
  lastlog_clean(_PATH_LASTLOG, user);
}

int uwtmp_clean(char *path, char *user) {
  FILE *uwtmp_file;
  struct utmp uwtmp_tmp;
  int count=0;

  if((uwtmp_file = fopen(path, "r+")) == NULL) {
    printf("[-] filed to open file '%s'\n", path);
    return 0;
  }
  
  while(fread((char *)&uwtmp_tmp, sizeof(uwtmp_tmp), 1, uwtmp_file) > 0) {
    if(strcmp(uwtmp_tmp.ut_name, user) ==0) {
      fseek(uwtmp_file, -sizeof(uwtmp_tmp), SEEK_CUR);
      bzero(&uwtmp_tmp, sizeof(uwtmp_tmp));
      fwrite((char *)&uwtmp_tmp, sizeof(uwtmp_tmp), 1, uwtmp_file);
      count++;
    }
  }
  
  fclose(uwtmp_file);
  
  if(count == 0) {
    printf("[-] user '%s' not found\n", user, path);
  }
  
  else printf("[+] '%s' cleaned!\n", path);

}

int lastlog_clean(char *path, char *user) {
  FILE *lastlog_file;
  struct passwd *pwd;
  struct lastlog lastlog_tmp;
  int count=0;

  if((lastlog_file = fopen(path, "r+")) == NULL) {
    printf("[-] filed to open file '%s'\n", path);
    return 0;
  }

  if ((pwd = getpwnam(user)) == NULL) {
       printf("[-] user '%s' not found\n", user);
       return 0;
    }

  fseek(lastlog_file, (long)(pwd->pw_uid*sizeof(lastlog_tmp)), SEEK_SET);
  bzero((char *)&lastlog_tmp, sizeof(lastlog_tmp));
  fwrite((char *)&lastlog_tmp, sizeof(lastlog_tmp), 1, lastlog_file);

  fclose(lastlog_file);

  printf("[+] '%s' cleaned!\n", path);

}

void use(char *program) {
  printf(" use: %s -u\tuser\n", program);
  printf("\t\t -v\tversion\n");
  exit(0);
}

void version(void) {
  printf(" logclean.c v%s by CoKi <coki@nosystem.com.ar>\n", VERSION);
  exit(0);
}