/* ftpparse.c, ftpparse.h: library for parsing FTP LIST responses
D. J. Bernstein, djb@pobox.com
19970712 (doc updated 19970810)
Commercial use is fine, if you let me know what programs you're using this in.

Currently covered:
EPLF.
UNIX ls, with or without gid.
Microsoft FTP Service.
Windows NT FTP Server.
VMS.
WFTPD (DOS).
NetPresenz (Mac).
NetWare.

Definitely not covered: 
Long VMS filenames, with information split across two lines.
NCSA Telnet FTP server. Has LIST = NLST (and bad NLST for directories).

Written for maximum portability, but tested only under UNIX so far.
*/

#include <time.h>
#include "ftpparse.h"

static long totai(year,month,mday)
long year;
long month;
long mday;
{
  /* adapted from datetime_untai() */
  /* about 100x faster than typical mktime() */
  long result;
  if (month >= 2) month -= 2;
  else { month += 10; --year; }
  result = (mday - 1) * 10 + 5 + 306 * month;
  result /= 10;
  if (result == 365) { year -= 3; result = 1460; }
  else result += 365 * (year % 4);
  year /= 4;
  result += 1461 * (year % 25);
  year /= 25;
  if (result == 36524) { year -= 3; result = 146096; }
  else { result += 36524 * (year % 4); }
  year /= 4;
  result += 146097 * (year - 5);
  result += 11017;
  return result * 86400;
}

static int flagneedbase = 1;
static time_t base; /* time() value on this OS at the beginning of 1970 TAI */
static long now; /* current time */
static int flagneedcurrentyear = 1;
static long currentyear; /* approximation to current year */

static void initbase()
{
  struct tm *t;
  if (!flagneedbase) return;

  base = 0;
  t = gmtime(&base);
  base = -(totai(t->tm_year + 1900,t->tm_mon,t->tm_mday) + t->tm_hour * 3600 + t->tm_min * 60 + t->tm_sec);
  /* time_t is assumed to be measured in TAI seconds. */
  /* base may be slightly off if time_t is measured in UTC seconds. */
  /* Typical software naively claims to use UTC but actually uses TAI. */
  flagneedbase = 0;
}

static void initnow()
{
  long day;
  long year;

  initbase();
  now = time((time_t *) 0) - base;

  if (flagneedcurrentyear) {
    /* adapted from datetime_tai() */
    day = now / 86400;
    if ((now % 86400) < 0) --day;
    day -= 11017;
    year = 5 + day / 146097;
    day = day % 146097;
    if (day < 0) { day += 146097; --year; }
    year *= 4;
    if (day == 146096) { year += 3; day = 36524; }
    else { year += day / 36524; day %= 36524; }
    year *= 25;
    year += day / 1461;
    day %= 1461;
    year *= 4;
    if (day == 1460) { year += 3; day = 365; }
    else { year += day / 365; day %= 365; }
    day *= 10;
    if ((day + 5) / 306 >= 10) ++year;
    currentyear = year;
    flagneedcurrentyear = 0;
  }
}

/* UNIX ls does not show the year for dates in the last six months. */
/* So we have to guess the year. */
/* Apparently NetWare uses ``twelve months'' instead of ``six months''; ugh. */
/* Some versions of ls also fail to show the year for future dates. */
static long guesstai(month,mday)
long month;
long mday;
{
  long year;
  long t = 0;

  initnow();

  for (year = currentyear - 1;year < currentyear + 100;++year) {
	t = totai(year,month,mday);
	if (now - t < 350 * 86400) {
		break;
	}
  }
  return t;
}

static int check(const char *buf, char *monthname)
{
  if ((buf[0] != monthname[0]) && (buf[0] != monthname[0] - 32)) return 0;
  if ((buf[1] != monthname[1]) && (buf[1] != monthname[1] - 32)) return 0;
  if ((buf[2] != monthname[2]) && (buf[2] != monthname[2] - 32)) return 0;
  return 1;
}

static char *months[12] = {
  "jan","feb","mar","apr","may","jun","jul","aug","sep","oct","nov","dec"
} ;

static int getmonth(const char *buf, int len)
{
  int i;
  if (len == 3)
    for (i = 0;i < 12;++i)
      if (check(buf,months[i])) return i;
  return -1;
}

static long getlong(const char *buf, int len)
{
  long u = 0;
  while (len-- > 0)
    u = u * 10 + (*(buf++) - '0');
  return u;
}

int ftp_parse(ftpparse *fp, const char *buf, int len)
{
  int i = 0;
  int j = 0;
  int state = 0;
  long size = 0;
  long year = 0;
  long month = -1;
  long mday = 0;
  long hour = 0;
  long minute = 0;

  fp->name = 0;
  fp->namelen = 0;
  fp->flagtrycwd = 0;
  fp->flagtryretr = 0;
  fp->sizetype = FTPPARSE_SIZE_UNKNOWN;
  fp->size = 0;
  fp->mtimetype = FTPPARSE_MTIME_UNKNOWN;
  fp->mtime = 0;
  fp->idtype = FTPPARSE_ID_UNKNOWN;
  fp->id = 0;
  fp->idlen = 0;

  if (len < 2) /* an empty name in EPLF, with no info, could be 2 chars */
    return 0;

  switch(*buf) {
    /* see http://pobox.com/~djb/proto/eplf.txt */
    /* "+i8388621.29609,m824255902,/,\tdev" */
    /* "+i8388621.44468,m839956783,r,s10376,\tRFCEPLF" */
    case '+':
      i = 1;
      for (j = 1;j < len;++j) {
        if (buf[j] == 9) {
	  fp->name = (char *)(buf + j + 1);
	  fp->namelen = len - j - 1;
	  return 1;
        }
        if (buf[j] == ',') {
	  switch(buf[i]) {
	    case '/':
	      fp->flagtrycwd = 1;
	      break;
	    case 'r':
	      fp->flagtryretr = 1;
	      break;
	    case 's':
	      fp->sizetype = FTPPARSE_SIZE_BINARY;
	      fp->size = getlong(buf + i + 1,j - i - 1);
	      break;
	    case 'm':
	      fp->mtimetype = FTPPARSE_MTIME_LOCAL;
	      initbase();
	      fp->mtime = base + getlong(buf + i + 1,j - i - 1);
	      break;
	    case 'i':
	      fp->idtype = FTPPARSE_ID_FULL;
	      fp->id = (char *)(buf + i + 1);
	      fp->idlen = j - i - 1;
	  }
	  i = j + 1;
        }
      }
      return 0;
    
    /* UNIX-style listing, without inum and without blocks */
    /* "-rw-r--r--   1 root     other        531 Jan 29 03:26 README" */
    /* "dr-xr-xr-x   2 root     other        512 Apr  8  1994 etc" */
    /* "dr-xr-xr-x   2 root     512 Apr  8  1994 etc" */
    /* "lrwxrwxrwx   1 root     other          7 Jan 25 00:17 bin -> usr/bin" */
    /* Also produced by Microsoft's FTP servers for Windows: */
    /* "----------   1 owner    group         1803128 Jul 10 10:18 ls-lR.Z" */
    /* "d---------   1 owner    group               0 May  9 19:45 Softlib" */
    /* Also WFTPD for MSDOS: */
    /* "-rwxrwxrwx   1 noone    nogroup      322 Aug 19  1996 message.ftp" */
    /* Also NetWare: */
    /* "d [R----F--] supervisor            512       Jan 16 18:53    login" */
    /* "- [R----F--] rhesus             214059       Oct 20 15:27    cx.exe" */
    /* Also NetPresenz for the Mac: */
    /* "-------r--         326  1391972  1392298 Nov 22  1995 MegaPhone.sit" */
    /* "drwxrwxr-x               folder        2 May 10  1996 network" */
    case 'b':
    case 'c':
    case 'd':
    case 'l':
    case 'p':
    case 's':
    case '-':

      if (*buf == 'd') fp->flagtrycwd = 1;
      if (*buf == '-') fp->flagtryretr = 1;
      if (*buf == 'l') fp->flagtrycwd = fp->flagtryretr = 1;

      state = 1;
      i = 0;
      for (j = 1;j < len;++j)
	if ((buf[j] == ' ') && (buf[j - 1] != ' ')) {
	  switch(state) {
	    case 1: /* skipping perm */
	      state = 2;
	      break;
	    case 2: /* skipping nlink */
	      state = 3;
	      if ((j - i == 6) && (buf[i] == 'f')) /* for NetPresenz */
		state = 4;
	      break;
	    case 3: /* skipping uid */
	      state = 4;
	      break;
	    case 4: /* getting tentative size */
	      size = getlong(buf + i,j - i);
	      state = 5;
	      break;
	    case 5: /* searching for month, otherwise getting tentative size */
	      month = getmonth(buf + i,j - i);
	      if (month >= 0)
		state = 6;
	      else
		size = getlong(buf + i,j - i);
	      break;
	    case 6: /* have size and month */
	      mday = getlong(buf + i,j - i);
	      state = 7;
	      break;
	    case 7: /* have size, month, mday */
	      if ((j - i == 4) && (buf[i + 1] == ':')) {
	        hour = getlong(buf + i,1);
	        minute = getlong(buf + i + 2,2);
		fp->mtimetype = FTPPARSE_MTIME_REMOTEMINUTE;
		initbase();
		fp->mtime = base + guesstai(month,mday) + hour * 3600 + minute * 60;
	      } else if ((j - i == 5) && (buf[i + 2] == ':')) {
	        hour = getlong(buf + i,2);
	        minute = getlong(buf + i + 3,2);
		fp->mtimetype = FTPPARSE_MTIME_REMOTEMINUTE;
		initbase();
		fp->mtime = base + guesstai(month,mday) + hour * 3600 + minute * 60;
	      }
	      else if (j - i >= 4) {
		year = getlong(buf + i,j - i);
		fp->mtimetype = FTPPARSE_MTIME_REMOTEDAY;
		initbase();
		fp->mtime = base + totai(year,month,mday);
	      }
	      else
		return 0;
	      fp->name = (char *)(buf + j + 1);
	      fp->namelen = len - j - 1;
	      state = 8;
	      break;
	    case 8: /* twiddling thumbs */
	      break;
	  }
	  i = j + 1;
	  while ((i < len) && (buf[i] == ' ')) ++i;
	}

      if (state != 8)
	return 0;

      fp->size = size;
      fp->sizetype = FTPPARSE_SIZE_ASCII;

      if (*buf == 'l')
	for (i = 0;i + 3 < fp->namelen;++i)
	  if (fp->name[i] == ' ')
	    if (fp->name[i + 1] == '-')
	      if (fp->name[i + 2] == '>')
	        if (fp->name[i + 3] == ' ') {
		  fp->namelen = i;
		  break;
		}

      /* eliminate extra NetWare spaces */
      if ((buf[1] == ' ') || (buf[1] == '['))
	if (fp->namelen > 3)
	  if (fp->name[0] == ' ')
	    if (fp->name[1] == ' ')
	      if (fp->name[2] == ' ') {
		fp->name += 3;
		fp->namelen -= 3;
	      }

      return 1;
  }

  /* MultiNet (some spaces removed from examples) */
  /* "00README.TXT;1      2 30-DEC-1996 17:44 [SYSTEM] (RWED,RWED,RE,RE)" */
  /* "CORE.DIR;1          1  8-SEP-1996 16:09 [SYSTEM] (RWE,RWE,RE,RE)" */
  /* and non-MutliNet VMS: */
  /* "CII-MANUAL.TEX;1  213/216  29-JAN-1996 03:33:12  [ANONYMOU,ANONYMOUS]   (RWED,RWED,,)" */
  for (i = 0;i < len;++i)
    if (buf[i] == ';')
      break;
  if (i < len) {
    fp->name = (char *)(buf);
    fp->namelen = i;
    if (i > 4)
      if (buf[i - 4] == '.')
        if (buf[i - 3] == 'D')
          if (buf[i - 2] == 'I')
            if (buf[i - 1] == 'R') {
	      fp->namelen -= 4;
	      fp->flagtrycwd = 1;
	    }
    if (!fp->flagtrycwd)
      fp->flagtryretr = 1;
    while (buf[i] != ' ') if (++i == len) return 0;
    while (buf[i] == ' ') if (++i == len) return 0;
    while (buf[i] != ' ') if (++i == len) return 0;
    while (buf[i] == ' ') if (++i == len) return 0;
    j = i;
    while (buf[j] != '-') if (++j == len) return 0;
    mday = getlong(buf + i,j - i);
    while (buf[j] == '-') if (++j == len) return 0;
    i = j;
    while (buf[j] != '-') if (++j == len) return 0;
    month = getmonth(buf + i,j - i);
    if (month < 0) return 0;
    while (buf[j] == '-') if (++j == len) return 0;
    i = j;
    while (buf[j] != ' ') if (++j == len) return 0;
    year = getlong(buf + i,j - i);
    while (buf[j] == ' ') if (++j == len) return 0;
    i = j;
    while (buf[j] != ':') if (++j == len) return 0;
    hour = getlong(buf + i,j - i);
    while (buf[j] == ':') if (++j == len) return 0;
    i = j;
    while ((buf[j] != ':') && (buf[j] != ' ')) if (++j == len) return 0;
    minute = getlong(buf + i,j - i);

    fp->mtimetype = FTPPARSE_MTIME_REMOTEMINUTE;
    initbase();
    fp->mtime = base + totai(year,month,mday) + hour * 3600 + minute * 60;

    return 1;
  }

  /* Some useless lines, safely ignored: */
  /* "Total of 11 Files, 10966 Blocks." (VMS) */
  /* "total 14786" (UNIX) */
  /* "DISK$ANONFTP:[ANONYMOUS]" (VMS) */
  /* "Directory DISK$PCSA:[ANONYM]" (VMS) */

  return 0;
}
