#include <unistd.h>
#include "stralloc.h"
#include "buffer.h"
#include "qmail.h"
#include "now.h"
#include "str.h"
#include "fmt.h"
#include "env.h"
#include "sig.h"
#include "case.h"
#include "exit.h"
#include "scan.h"
#include "rcpthosts.h"
#include "auto_qmail.h"
#include "control.h"
#include "received.h"
#include "ip.h"
#include "byte.h"

#define PORT_QMTPS   "6209"  // string compare
#define QMTP_SIZE 200000000  // 23 MB transfer limit
#define QMTP_TIMEOUT   3600  // 1 hour

/** @file qmail-qmtpd.c -- QMTP/QMTPS server
    @brief requires sslserver */

void badproto() { _exit(100); }
void resources() { _exit(111); }

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

char outbuf[BUFSIZE_LINE];
buffer bo = BUFFER_INIT(safewrite,1,outbuf,sizeof(outbuf));

ssize_t saferead(int fd,char *buf,int len)
{
  int r;
  buffer_flush(&bo);
  r = read(fd,buf,len);
  if (r <= 0) _exit(0);
  return r;
}

char inbuf[BUFSIZE_MESS];              // at least 2*outbuf
buffer bi = BUFFER_INIT(saferead,0,inbuf,sizeof(inbuf));

unsigned long getlen()
{
  unsigned long len = 0;
  char ch;
  for (;;) {
    buffer_get(&bi,&ch,1);
    if (ch == ':') return len;
    if (ch < '0' || ch > '9') resources();
    if (len > QMTP_SIZE) resources();
    len = 10 * len + (ch - '0');
  }
}

void getcomma()
{
  char ch;
  buffer_get(&bi,&ch,1);
  if (ch != ',') badproto();
}

unsigned int databytes = 0;
unsigned int bytestooverflow = 0;
struct qmail qq;

char buf[BUFSIZE_LINE];      // sender/recipient buffer
char bufd[BUFSIZE_MESS];     // temporary data buffer
char buf2[BUFFER_SMALL];     // QMTP message buffer

char *remotehost;
char *remoteinfo;
char *remoteip;
char *localport;
char *local;

stralloc failure = {0};
stralloc protocol = {0};
stralloc tlsinfo = {0};

char *relayclient;
int relayclientlen = 0;

char *ucspitls;
char *tlsversion;
char *cipher;
char *cipherperm;
char *cipherused;
char *clientdn;
char *clientcn;
char *dnemail;

int seentls = 0;

int modssl_info()
{
  tlsversion = env_get("SSL_PROTOCOL");
  if (!tlsversion) return 0;
  seentls = 1;

  cipher = env_get("SSL_CIPHER");
  if (!cipher) cipher = "unknown";
  cipherperm = env_get("SSL_CIPHER_ALGKEYSIZE");
  if (!cipherperm) cipherperm = "unknown";
  cipherused = env_get("SSL_CIPHER_USEKEYSIZE");
  if (!cipherused) cipherused = "unknown";
  clientdn = env_get("SSL_CLIENT_S_DN");
  if (clientdn) seentls = 2;
  else
    clientdn = "none";

  if (!stralloc_copys(&tlsinfo,tlsversion)) resources();
  if (!stralloc_cats(&tlsinfo,": ")) resources();
  if (!stralloc_cats(&tlsinfo,cipher)) resources();
  if (!stralloc_cats(&tlsinfo," [")) resources();
  if (!stralloc_cats(&tlsinfo,cipherused)) resources();
  if (!stralloc_cats(&tlsinfo,"/")) resources();
  if (!stralloc_cats(&tlsinfo,cipherperm)) resources();
  if (!stralloc_cats(&tlsinfo,"] \n")) resources();
  if (!stralloc_cats(&tlsinfo,"  DN=")) resources();
  if (!stralloc_cats(&tlsinfo,clientdn)) resources();
  if (!stralloc_0(&tlsinfo)) resources();

  if (!stralloc_append(&protocol,"S")) resources();

  if (seentls == 2) {
    clientcn = env_get("SSL_CLIENT_S_DN_CN");
    remoteinfo =  clientcn ? clientcn : clientdn;
    dnemail = env_get("SSL_CLIENT_S_DN_Email");
    if (!dnemail) dnemail = "unknown";
    if (!stralloc_append(&protocol,"A")) resources();
    relayclient = "";
  }
  return 1;
}

int main()
{
  char ch;
  int i;
  unsigned long biglen;
  unsigned long dlen;
  unsigned long len;
  int flagdos;
  int flagsenderok;
  int flagbother;
  unsigned long qp;
  char *result;
  char *x;
  unsigned long u;
 
  sig_pipeignore();
  sig_alarmcatch(resources);
  alarm(QMTP_TIMEOUT);
 
  if (chdir(auto_qmail) == -1) resources();
 
  if (control_init() == -1) resources();
  if (rcpthosts_init() == -1) resources();

  if (control_readint(&databytes,"control/databytes") == -1) resources();
  x = env_get("DATABYTES");
  if (x) { scan_ulong(x,&u); databytes = u; }
  if (!(databytes + 1)) --databytes;
 
  relayclient = env_get("RELAYCLIENT");
  remotehost = env_get("TCP6REMOTEHOST");
  if (!remotehost) remotehost = env_get("TCPREMOTEHOST");
  if (!remotehost) remotehost = "unknown";
  remoteinfo = env_get("TCP6REMOTEINFO");
  if (!remoteinfo) remoteinfo = env_get("TCPREMOTEINFO");
  remoteip = env_get("TCP6REMOTEIP");
  if (!remoteip) remoteip = env_get("TCPREMOTEIP");
  if (remoteip && byte_equal(remoteip,7,V4MAPPREFIX)) remoteip = remoteip + 7;
  if (!remoteip) remoteip = "unknown";
  local = env_get("TCP6LOCALHOST");
  if (!local) local = env_get("TCPLOCALHOST");
  if (!local) local = env_get("TCP6LOCALIP");
  if (!local) local = env_get("TCPLOCALIP");
  if (!local) local = "unknown";
  localport = env_get("TCP6LOCALPORT");
  if (!localport) localport  = env_get("TCPLOCALPORT");
  if (!localport) localport = "0";
 
  if (!stralloc_copys(&protocol,"QMTP")) resources();
  if (!case_diffs(localport,PORT_QMTPS)) 
    if (!modssl_info()) resources();

  if (relayclient)
    relayclientlen = str_len(relayclient);
 
  for (;;) {                                     // https://cr.yp.to/proto/qmtp.txt
    if (!stralloc_copys(&failure,"")) resources();
    flagsenderok = 1;
 
    len = getlen();                              // package to read
    if (len == 0) badproto();
 
    if (databytes) bytestooverflow = databytes + 1;
    if (qmail_open(&qq) == -1) resources();
    qp = qmail_qp(&qq);
 
    buffer_get(&bi,&ch,1);
    --len;
    if (ch == 10) flagdos = 0;
    else if (ch == 13) flagdos = 1;
    else badproto();

    /* no fakehelo, no spfinfo */
 
    received(&qq,protocol.s,local,remoteip,remotehost,remoteinfo,(char *) 0,tlsinfo.s,(char *) 0);
 
    /* XXX: check for loops? only if len is big? - message */
 
    if (flagdos)
      while (len > 0) {
        buffer_get(&bi,&ch,1);
        --len;
        while ((ch == 13) && len) {
          buffer_get(&bi,&ch,1);
          --len;
          if (ch == 10) break;
          if (bytestooverflow) if (!--bytestooverflow) qmail_fail(&qq);
          qmail_put(&qq,"\015",1);
        }
        if (bytestooverflow) if (!--bytestooverflow) qmail_fail(&qq);
        qmail_put(&qq,&ch,1);
      }
    else {
      if (databytes)
        if (len > databytes) {
          bytestooverflow = 0;
          qmail_fail(&qq);
        }
      while (len > 0) { /* XXX: DJB: could speed this up, obviously; FEH: done */
        dlen = (len < BUFSIZE_LINE) ? len : BUFSIZE_LINE;
        buffer_get(&bi,bufd,dlen);
        qmail_put(&qq,bufd,dlen);
        len -= dlen;
      }
    }
    getcomma();
 
    len = getlen();                              // QMTP sender
 
    if (len >= BUFSIZE_LINE) {
      buf[0] = 0;
      flagsenderok = 0;
      for (i = 0; i < len; ++i)
        buffer_get(&bi,&ch,1);
    }
    else {
      for (i = 0; i < len; ++i) {
        buffer_get(&bi,buf + i,1);
        if (!buf[i]) flagsenderok = 0;
      }
      buf[len] = 0;
    }
    getcomma();
 
    flagbother = 0;
    qmail_from(&qq,buf);
    if (!flagsenderok) qmail_fail(&qq);
 
    biglen = getlen();                           // QMTP recipients
    while (biglen > 0) {
      if (!stralloc_append(&failure,"")) resources();
 
      len = 0;
      for (;;) {
        if (!biglen) badproto();
        buffer_get(&bi,&ch,1);
        --biglen;
        if (ch == ':') break;
        if (ch < '0' || ch > '9') resources();
        if (len > QMTP_SIZE) resources();
        len = 10 * len + (ch - '0');
      }
      if (len >= biglen) badproto();
      if (len + relayclientlen >= BUFSIZE_LINE) {
        failure.s[failure.len - 1] = 'L';
        for (i = 0; i < len; ++i)
          buffer_get(&bi,&ch,1);
      }
      else {
        for (i = 0; i < len; ++i) {
          buffer_get(&bi,buf + i,1);
          if (!buf[i]) failure.s[failure.len - 1] = 'N';
        }
        buf[len] = 0;
 
        if (relayclientlen) 
          str_copy(buf + len,relayclient);
        if (!relayclient) 
          switch (rcpthosts(buf,len)) {
            case -1: resources();
            case 0: failure.s[failure.len - 1] = 'D';
          }
 
        if (!failure.s[failure.len - 1]) {
          qmail_to(&qq,buf);
          flagbother = 1;
        }
      }
      getcomma();
      biglen -= (len + 1);
    }
    getcomma();
 
    if (!flagbother) qmail_fail(&qq);
    result = qmail_close(&qq);
    if (!flagsenderok) result = "D Unacceptable sender (#5.1.7)";
    if (databytes) if (!bytestooverflow) result = "D Sorry, that message size exceeds my databytes limit (#5.3.4)";
 
    if (*result)
      len = str_len(result);
    else {
      /* success! */
      len = 0;
      len += fmt_str(buf2 + len,"K Ok ");
      len += fmt_ulong(buf2 + len,(unsigned long) now());
      len += fmt_str(buf2 + len," qp ");
      len += fmt_ulong(buf2 + len,qp);
      buf2[len] = 0;
      result = buf2;
    }
      
    len = fmt_ulong(buf,len);
    buf[len++] = ':';
    len += fmt_str(buf + len,result);
    buf[len++] = ',';
 
    for (i = 0; i < failure.len; ++i)
      switch (failure.s[i]) {
        case 0:
          buffer_put(&bo,buf,len);
          break;
        case 'D':
          buffer_puts(&bo,"66:D Sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1),");
          break;
        default:
          buffer_puts(&bo,"46:D Sorry, I can't handle that recipient (#5.1.3),");
          break;
      }
 
    /* bo will be flushed when we read from the network again */
  }
}