#include <unistd.h>
#include "commands.h"
#include "fd.h"
#include "sig.h"
#include "stralloc.h"
#include "buffer.h"
#include "alloc.h"
#include "wait.h"
#include "str.h"
#include "byte.h"
#include "now.h"
#include "fmt.h"
#include "case.h"
#include "exit.h"
#include "timeout.h"
#include "env.h"
#include "tls_start.h"
#include "ip.h"
#include "qmail.h"

#define PORT_POP3S "995" // string
#define FDIN   0
#define FDOUT  1
#define FDAUTH 3
#define FDLOG  5
#define POP3_TIMEOUT 1200

void die() { _exit(1); }

ssize_t saferead(int fd,char *buf,int len)
{
  int r;
  r = timeoutread(POP3_TIMEOUT,fd,buf,len);
  if (r <= 0) die();
  return r;
}

ssize_t safewrite(int fd,char *buf,int len)
{
  int r;
  r = timeoutwrite(POP3_TIMEOUT,fd,buf,len);
  if (r <= 0) die();
  return r;
}

char inbuf[BUFSIZE_AUTH];
buffer bi = BUFFER_INIT(saferead,FDIN,inbuf,sizeof(inbuf));

char outbuf[BUFSIZE_AUTH];
buffer bo = BUFFER_INIT(safewrite,FDOUT,outbuf,sizeof(outbuf));

void outs(char *s)
{
  buffer_puts(&bo,s);
}
void flush()
{
  buffer_flush(&bo);
}
void err(char *s)
{
  outs("-ERR ");
  outs(s);
  outs("\r\n");
  flush();
}

/* Logging */

stralloc protocol = {0};  
stralloc auth = {0};
char *localport;
char *remoteip;
char *remotehost;

char strnum[FMT_ULONG];
char logbuf[BUFSIZE_LOG];
buffer bl = BUFFER_INIT(safewrite,FDLOG,logbuf,sizeof(logbuf));

void logs(char *s) { if (buffer_puts(&bl,s) == -1) _exit(1); }
void logp(char *s) { logs(" P:"); logs(s); }
void logh(char *s1, char *s2) { logs(" S:"); logs(s1); logs(":"); logs(s2); }  
void logu(char *s) { logs(" ?~ '"); logs(s); logs("'"); }  
void logn(char *s) { if (buffer_puts(&bl,s) == -1) _exit(1); if (buffer_flush(&bl) == -1) _exit(1); }
void logpid() { strnum[fmt_ulong(strnum,getpid())] = 0; logs("qmail-popup: pid "); logs(strnum); logs(" "); }
void log_pop(char *s1,char *s2,char *s3,char *s4,char *s5,char *s6)  
  { logpid(); logs(s1); logs(s2); logp(s3); logh(s4,s5), logu(s6), logn("\n"); }

void die_usage() { err("usage: popup hostname subprogram"); die(); }
void die_nomem() { err("out of memory"); die(); }
void die_pipe() { err("unable to open pipe"); die(); }
void die_write() { err("unable to write pipe"); die(); }
void die_fork() { err("unable to fork"); die(); }
void die_childcrashed() { err("aack, child crashed"); }
void die_badauth() { err("authorization failed"); }
void die_tls() { err("TLS startup failed"); die(); }
void die_notls() { 
  err("TLS required but not negotiated"); 
  log_pop("Reject::STLS::","Any","POP3",remoteip,remotehost,"unknown");
  die(); 
}

void err_syntax() { err("syntax error"); }
void err_wantuser() { err("USER first"); }
void err_authoriz() { err("authorization first"); }

void okay() { outs("+OK \r\n"); flush(); }
void pop3_quit() { okay(); die(); }

void poplog_init()
{
  if (!stralloc_copys(&protocol,"POP3")) die_nomem();
  localport = env_get("TCP6LOCALPORT");
  if (!localport) localport  = env_get("TCPLOCALPORT");
  if (!localport) localport = "unknown";
  if (!case_diffs(localport,PORT_POP3S))
    if (!stralloc_cats(&protocol,"S")) die_nomem();
  remoteip = env_get("TCP6REMOTEIP");
  if (remoteip && byte_equal(remoteip,7,V4MAPPREFIX)) remoteip = remoteip + 7; 
  if (!remoteip) remoteip  = env_get("TCPREMOTEIP");
  if (!remoteip) remoteip = "unknown";
  remotehost = env_get("TCP6REMOTEHOST");
  if (!remotehost) remotehost = env_get("TCPREMOTEHOST");
  if (!remotehost) remotehost = "unknown";
}

char unique[FMT_ULONG + FMT_ULONG + 3];
char *hostname;
stralloc username = {0};
int seenuser = 0;
char **childargs;
char authbuf[BUFSIZE_AUTH];
buffer ba;
int stls = 0;
int seenstls = 0;
int apop = 0;

void doanddie(char *user,unsigned int userlen,char *pass) /* userlen: including 0 byte */
{
  int child;
  int wstat;
  int pi[2];
 
  if (fd_copy(2,1) == -1) die_pipe(); 
  close(FDAUTH);
  if (pipe(pi) == -1) die_pipe();
  if (pi[0] != FDAUTH) die_pipe();
  switch (child = fork()) {
    case -1:
      die_fork();
    case 0:
      close(pi[1]);
      sig_pipedefault();
      execvp(*childargs,childargs);
      _exit(1);
  }
  close(pi[0]);
  buffer_init(&ba,write,pi[1],authbuf,sizeof(authbuf));
  if (buffer_put(&ba,user,userlen) == -1) die_write();
  if (buffer_put(&ba,pass,str_len(pass) + 1) == -1) die_write();
  if (buffer_puts(&ba,"<") == -1) die_write();
  if (buffer_puts(&ba,unique) == -1) die_write();
  if (buffer_puts(&ba,hostname) == -1) die_write();
  if (buffer_put(&ba,">",2) == -1) die_write();
  if (buffer_flush(&ba) == -1) die_write();
  close(pi[1]);
  byte_zero(pass,str_len(pass));
  byte_zero(authbuf,sizeof(authbuf));
  if (wait_pid(&wstat,child) == -1) die();
  if (wait_crashed(wstat)) die_childcrashed();
  if (!stralloc_0(&auth)) die_nomem();
  if (!stralloc_0(&protocol)) die_nomem();
  if (wait_exitcode(wstat)) { 
    die_badauth(); 
    log_pop("Reject::AUTH::",auth.s,protocol.s,remoteip,remotehost,user); 
  }
  else
    log_pop("Accept::AUTH::",auth.s,protocol.s,remoteip,remotehost,user); 
  die();
}

void pop3_greet()
{
  char *s;
  s = unique;
  s += fmt_uint(s,getpid());
  *s++ = '.';
  s += fmt_ulong(s,(unsigned long) now());
  *s++ = '@';
  *s++ = 0;

  if (!apop)
    outs("+OK\r\n");
  else {
    outs("+OK <");
    outs(unique);
    outs(hostname);
    outs(">\r\n");
  }
  flush();
}

void pop3_user(char *arg)
{
  if (stls == 2 && !seenstls) die_notls();
  if (!*arg) { err_syntax(); return; }
  okay();
  seenuser = 1;
  if (!stralloc_copys(&username,arg)) die_nomem(); 
  if (!stralloc_0(&username)) die_nomem(); 
}

void pop3_pass(char *arg)
{
  if (!seenuser) { err_wantuser(); return; }
  if (!*arg) { err_syntax(); return; }
  if (!stralloc_copys(&auth,"User")) die_nomem();
  doanddie(username.s,username.len,arg);
}

void pop3_apop(char *arg)
{
  char *space;

  if (stls == 2 && !seenstls) die_notls();
  space = arg + str_chr(arg,' ');
  if (!*space) { err_syntax(); return; }
  *space++ = 0;
  if (!stralloc_copys(&auth,"Apop")) die_nomem();
  doanddie(arg,space - arg,space);
}

void pop3_capa(char *arg)
{
  outs("+OK capability list follows\r\n");
  outs("TOP\r\n");
  outs("USER\r\n");
  outs("UIDL\r\n");
  if (apop)
    outs("APOP\r\n");
  if (stls > 0) 
    outs("STLS\r\n");
  outs(".\r\n");
  flush();
}

void pop3_stls(char *arg)
{
  if (stls == 0 || seenstls == 1)
    return err("STLS not available");
  outs("+OK starting TLS negotiation\r\n");
  flush();

  if (!starttls_init()) die_tls();
  buffer_init(&bi,saferead,FDIN,inbuf,sizeof(inbuf));
  seenstls = 1;
  
/* reset state */
  seenuser = 0;
  if (!stralloc_cats(&protocol,"S")) die_nomem();
}

struct commands pop3commands[] = {
  { "user", pop3_user, 0 }
, { "pass", pop3_pass, 0 }
, { "apop", pop3_apop, 0 }
, { "quit", pop3_quit, 0 }
, { "capa", pop3_capa, 0 }
, { "stls", pop3_stls, 0 }
, { "noop", okay, 0 }
, { 0, err_authoriz, 0 }
};

int main(int argc,char **argv)
{
  char *pop3auth;
  char *ucspitls;

  sig_alarmcatch(die);
  sig_pipeignore();
 
  hostname = argv[1];
  if (!hostname) die_usage();
  childargs = argv + 2;
  if (!*childargs) die_usage();

  ucspitls = env_get("UCSPITLS");
  if (ucspitls) {
    stls = 1;
    if (!case_diffs(ucspitls,"-")) stls = 0;
    if (!case_diffs(ucspitls,"!")) stls = 2;
  }

  pop3auth = env_get("POP3AUTH");
  if (pop3auth) {
    if (case_starts(pop3auth,"apop")) apop = 2;
    if (case_starts(pop3auth,"+apop")) apop = 1;
  }
  poplog_init(); 
  pop3_greet();
  commands(&bi,pop3commands);
  die();
}