#include <stdlib.h>             /* for exit(), getenv() */
#include <iostream>
#include <string>

#include <sys/types.h>          /* for stat() */
#include <sys/stat.h>           /* for stat() */
#include <unistd.h>             /* for stat() */
#include <stdio.h>              /* for perror */
#include <errno.h>              /* for ENOENT */
#include <fstream>              /* for ofstream() */
#include <fcntl.h>              /* for creat() */
#include <sys/time.h>           /* for gettimeofday() */

using namespace std;

const int sa_good = 0;
const int bug_bait_grey = 1;
// qmail_queue and spamc have similar interpretations here:
const int sa_syserr = 71;

pid_t mypid;
string progname;

void dump(const string var){
  char* str = getenv(var.c_str());
  cerr << progname
    << "[" << mypid << "] "
    << var;
  if (str) cerr << " is set to '" << str << "'" << endl;
  else  cerr << " is not set." << endl;
}

const string dirname("/var/qmail/greylist");

   //       int stat(const char *path, struct stat *buf);
   //       int fstat(int fd, struct stat *buf);
   //       int lstat(const char *path, struct stat *buf);

const int minute(60);
const int hour(60*minute);
const int day(24*hour);

class whatsit{
public:
  string progname;
  pid_t mypid;
  timeval now;
  string ipname;
  int mod_age;
  int ac_age;

  whatsit(const string name)
  : progname(name), mypid(getpid())
  {
    gettimeofday(&now, NULL);
  }
  int doit();
// access comes after modification:
  void update(const string msg, const timeval new_mod, const timeval new_ac);
};

void whatsit::update(const string msg, const timeval new_mod, const timeval new_ac){
  cerr << progname << ": "
       << msg << ": " << ipname
          << "  mod_age: " << mod_age
          << "  ac_age: " << ac_age
          << endl;
  timeval upd[2] = {
// beware:  access illogically comes *before* modification here:
    new_ac,
    new_mod
  };
  utimes(ipname.c_str(), upd);
}

int main(int argc, char** argv){

//  dump("TCPREMOTEIP");
//  dump("TCPREMOTEHOST");

  whatsit foo(argv[0]);
  return foo.doit();
}

int whatsit::doit(){
  char* ipvar = getenv("TCPREMOTEIP");
  if (!ipvar) {
    cerr << progname << ": TCPREMOTEIP not set???" << endl;
    exit(sa_syserr);
  }
  string ipbase = ipvar;

// see if our directory exists:
  struct stat dirstat;
  int rslt = stat(dirname.c_str(), &dirstat);
  if (rslt != 0){
    if (errno != ENOENT) {
      cerr << progname << ": stat failed for '"
        << dirname << "' : ";
      perror(0);
    }
    rslt = mkdir(dirname.c_str(), 0755);
    if (rslt != 0) {
      cerr << progname
        << "uid " << getuid()
        << ": mkdir failed for '"
        << dirname << "' : ";
      perror(0);
      exit(sa_syserr);
    }
  }

  ipname = dirname + "/" + ipbase;
  struct stat ipstat;
  rslt = stat(ipname.c_str(), &ipstat);
  if (rslt != 0){
    if (errno != ENOENT) {
      cerr << progname << ": stat failed for '"
        << ipname << "' : ";
      perror(0);
    }
    ofstream foo;
    int fd = creat(ipname.c_str(), 0644);
    if (fd < 0){
      cerr << progname << ": create failed for '"
        << ipname << "' : ";
      perror(0);
    }
    close(fd);
    update("new customer", now, now);
    return(bug_bait_grey);
  }
// here if stat succeeded
  mod_age = now.tv_sec - ipstat.st_mtime;
  ac_age = now.tv_sec - ipstat.st_atime;
  timeval mod_orig = {ipstat.st_mtime, 0};
  if (mod_age < 5*minute) {
    update("early bird", mod_orig, now);
    return(bug_bait_grey);
  }
  if (ac_age < 32*day) {
    update("returning customer", mod_orig, now);
    return 0;
  }

// here if it is too old:
  update("too old, starting over", now, now);
  return(bug_bait_grey);
}