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vegetarise.c
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vegetarise.c
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/* vegetarise.c - A spam filter based on Paul Graham's idea
* Copyright (C) 2002 Werner Koch
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*
* $Id: vegetarise.c,v 1.6 2004/09/11 14:51:51 werner Exp $
*/
/* How to use:
*
* # Put this at the top of your ~/.procmailrc:
* #
* VEGETARISE_SOCKET=$HOME/.vegetarise-socket
* # After basic filtering, e.g. throwing away all chinese stuff and the
* # worm of the day, add a rule like:
* :0
* * ? vegetarise -s $HOME/Mail/words
* spamfolder2/
*
*
* To intialize vegetarise you need to have collections of spam and
* vegetarian mails. For example, if you have sorted them into two
* mbox files:
*
* vegetarise -l veg.mbox spam.mbox >words
*
* To add new stuff to an esisting word list, use this:
*
* vegetarise -l veg.mbox spam.mbox oldwords >words
*
* If you don't have mbox files but two files each with a list of mails
* (MH or Maildir format), you can use this:
*
* vegetarise -L veg-files.list spam-files.list oldwords >words
*
* It can either be run standalone (usually slow) or in auto server
* mode (using option -s).
**/
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <stdarg.h>
#include <ctype.h>
#include <errno.h>
#include <assert.h>
#ifdef HAVE_PTH /* In theory we could use sockets without Pth but it
does not make much sense to we require it. */
#include <signal.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <pth.h>
#endif /*HAVE_PTH*/
#define PGMNAME "vegetarise"
#define MAX_WORDLENGTH 50 /* max. length of a word */
#define MAX_WORDS 15 /* max. number of words to look at. */
/* A list of token characters. There is explicit code for 8bit
characters. */
#define TOKENCHARS "abcdefghijklmnopqrstuvwxyz" \
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
"0123456789-_'$"
#ifdef __GNUC__
#define inline __inline__
#else
#define inline
#endif
#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 5)
#define ATTR_PRINTF(a,b) __attribute__ ((format (printf,a,b)))
#define ATTR_NR_PRINTF(a,b) __attribute__ ((noreturn,format (printf,a,b)))
#else
#define ATTR_PRINTF(a,b)
#define ATTR_NR_PRINTF(a,b)
#endif
#define DIM(v) (sizeof(v)/sizeof((v)[0]))
#define DIMof(type,member) DIM(((type *)0)->member)
#ifdef HAVE_PTH
# define my_read(a,b,c) pth_read ((a),(b),(c))
# define my_write(a,b,c) pth_write ((a),(b),(c))
# define YIELD do { if (running_as_server) pth_yield (NULL); } while (0)
#else
# define my_read(a,b,c) read ((a),(b),(c))
# define my_write(a,b,c) write ((a),(b),(c))
# define YIELD do { ; } while (0)
#endif
#define xtoi_1(a) ((a) <= '9'? ((a)- '0'): \
(a) <= 'F'? ((a)-'A'+10):((a)-'a'+10))
#define xtoi_2(a,b) ((xtoi_1(a) * 16) + xtoi_1(b))
struct pushback_s {
int buflen;
char buf[100];
int nl_seen;
int state;
int base64_nl;
int base64_val;
int qp1;
};
typedef struct pushback_s PUSHBACK;
struct hash_entry_s {
struct hash_entry_s *next;
unsigned int veg_count;
unsigned int spam_count;
unsigned int hit_ref; /* reference to the hit table. */
char prob; /* range is 1 to 99 or 0 for not calculated */
char word [1];
};
typedef struct hash_entry_s *HASH_ENTRY;
struct hit_array_s {
size_t size; /* Allocated size. */
unsigned int *hits;
};
typedef struct hit_array_s *HIT_ARRAY;
/* Option flags. */
static int verbose;
static int name_only;
/* Flag to indicate that we are running as a server. */
static int running_as_server;
/* Keep track of memory used for debugging. */
static size_t total_memory_used;
/* The global table with the words and its size. */
static int hash_table_size;
static HASH_ENTRY *word_table;
/* When storing a new word, we assign a hit reference id to it, so
that we can index a hit table. The variable keeps tracks of the
used reference numbers. */
static unsigned int next_hit_ref;
/* Number of good and bad messages the word table is made up. */
static unsigned int srvr_veg_count, srvr_spam_count;
/* Base64 conversion tables. */
static unsigned char bintoasc[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
static unsigned char asctobin[256]; /* runtime initialized */
/* Prototypes. */
static void die (const char *format, ...) ATTR_NR_PRINTF(1,2);
static void error (const char *format, ...) ATTR_PRINTF(1,2);
static void info (const char *format, ...) ATTR_PRINTF(1,2);
/*
Helper
*/
static void
die (const char *fmt, ...)
{
va_list arg_ptr;
va_start (arg_ptr, fmt);
fputs (PGMNAME": fatal error: ", stderr);
vfprintf (stderr, fmt, arg_ptr);
va_end (arg_ptr);
exit (1);
}
static void
error (const char *fmt, ...)
{
va_list arg_ptr;
va_start (arg_ptr, fmt);
fputs (PGMNAME": error: ", stderr);
vfprintf (stderr, fmt, arg_ptr);
va_end (arg_ptr);
}
static void
info (const char *fmt, ...)
{
va_list arg_ptr;
va_start (arg_ptr, fmt);
fputs (PGMNAME": ", stderr);
vfprintf (stderr, fmt, arg_ptr);
va_end (arg_ptr);
}
static void *
xmalloc (size_t n)
{
void *p = malloc (n);
if (!p)
die ("out of core\n");
total_memory_used += n;
return p;
}
static void *
xcalloc (size_t n, size_t k)
{
void *p = calloc (n, k);
if (!p)
die ("out of core\n");
total_memory_used += n * k;
return p;
}
static inline unsigned int
hash_string (const char *s)
{
unsigned int h = 0;
unsigned int g;
while (*s)
{
h = (h << 4) + *s++;
if ((g = (h & (unsigned int) 0xf0000000)))
h = (h ^ (g >> 24)) ^ g;
}
return (h % hash_table_size);
}
static void
pushback (PUSHBACK *pb, int c)
{
if (pb->buflen < sizeof pb->buf)
pb->buf[pb->buflen++] = c;
else
error ("comment parsing problem\n");
}
static inline int
basic_next_char (FILE *fp, PUSHBACK *pb)
{
int c;
if (pb->buflen)
{
c = *pb->buf;
if (--pb->buflen)
memmove (pb->buf, pb->buf+1, pb->buflen);
}
else
{
c = getc (fp);
if (c == EOF)
return c;
}
/* check for HTML comment - we only use the limited syntax:
"<!--" ... "-->" */
while (c == '<')
{
if ((c=getc (fp)) == EOF)
return c;
pushback (pb, c);
if ( c != '!' )
return '<';
if ((c=getc (fp)) == EOF)
{
pb->buflen = 0;;
return EOF; /* This misses the last chars but who cares. */
}
pushback (pb, c);
if ( c != '-' )
return '<';
if ((c=getc (fp)) == EOF)
{
pb->buflen = 0;
return EOF; /* This misses the last chars but who cares. */
}
pushback (pb, c);
if ( c != '-' )
return '<';
pb->buflen = 0;
/* found html comment - skip to end */
do
{
while ( (c = getc (fp)) != '-')
{
if (c == EOF)
return EOF;
}
if ( (c=getc (fp)) == EOF)
return EOF;
}
while ( c != '-' );
while ( (c = getc (fp)) != '>')
{
if (c == EOF)
return EOF;
}
c = getc (fp);
}
return c;
}
static inline int
next_char (FILE *fp, PUSHBACK *pb)
{
int c, c2;
next:
if ((c=basic_next_char (fp, pb)) == EOF)
return c;
switch (pb->state)
{
case 0: break;
case 1:
if (pb->nl_seen && (c == '\r' || c == '\n'))
{
pb->state = 2;
goto next;
}
break;
case 2:
if (!strchr (bintoasc, c))
break;
pb->nl_seen = 0;
pb->base64_nl = 0;
pb->state = 3;
/* fall through */
case 3: /* 1. base64 byte */
case 4: /* 2. base64 byte */
case 5: /* 3. base64 byte */
case 6: /* 4. base64 byte */
if (c == '\n')
{
pb->base64_nl = 1;
goto next;
}
if (pb->base64_nl && c == '-')
{
pb->state = 0; /* end of mime part */
c = ' '; /* make sure that last token gets processed. */
break;
}
pb->base64_nl = 0;
if (c == ' ' || c == '\r' || c == '\t')
goto next; /* skip all other kind of white space */
if (c == '=' )
goto next; /* we ignore the stop character and rely on
the MIME boundary */
if ((c = asctobin[c]) == 255 )
goto next; /* invalid base64 character */
switch (pb->state)
{
case 3:
pb->base64_val = c << 2;
pb->state = 4;
goto next;
case 4:
pb->base64_val |= (c>>4)&3;
c2 = pb->base64_val;
pb->base64_val = (c<<4)&0xf0;
c = c2;
pb->state = 5;
break; /* deliver C */
case 5:
pb->base64_val |= (c>>2)&15;
c2 = pb->base64_val;
pb->base64_val = (c<<6)&0xc0;
c = c2;
pb->state = 6;
break; /* deliver C */
case 6:
pb->base64_val |= c&0x3f;
c = pb->base64_val;
pb->state = 3;
break; /* deliver C */
}
break;
case 101: /* quoted-printable */
if (pb->nl_seen && (c == '\r' || c == '\n'))
{
pb->state = 102;
goto next;
}
break;
case 102:
if (pb->nl_seen && (c == '-'))
{
pb->state = 105;
goto next;
}
else if ( c == '=' )
{
pb->state = 103;
goto next;
}
break;
case 103:
if ( isxdigit (c) )
{
pb->qp1 = c;
pb->state = 104;
goto next;
}
pb->state = 102;
break;
case 104:
if ( isxdigit (c) )
c = xtoi_2 (pb->qp1, c);
pb->state = 102;
break;
case 105:
if (c == '-')
{
pb->state = 106;
goto next;
}
pb->state = 102;
break; /* we drop one, but that's okay for this application */
case 106:
if ( isspace (c) )
{
pb->state = 0; /* assume end of mime part */
c = ' '; /* make sure that last token gets processed. */
}
else
pb->state = 102;
break;
}
return c;
}
static void
enlarge_hit_array (HIT_ARRAY ha)
{
unsigned int *arr;
size_t i, n;
n = ha->size + 100;
arr = xmalloc (n * sizeof *arr);
for (i=0; i < ha->size; i++)
arr[i] = ha->hits[i];
for (; i < n; i++)
arr[i] = 0;
free (ha->hits);
ha->hits = arr;
ha->size = n;
}
static HIT_ARRAY
new_hit_array (void)
{
HIT_ARRAY ha = xmalloc (sizeof *ha);
/* Create the array with space for extra 1000 words */
ha->size = next_hit_ref + 1000;
ha->hits = xcalloc (ha->size, sizeof *ha->hits);
return ha;
}
static void
release_hit_array (HIT_ARRAY ha)
{
if (ha)
{
free (ha->hits);
free (ha);
}
}
/*
real processing stuff
*/
static HASH_ENTRY
store_word (const char *word, int *is_new)
{
unsigned int hash = hash_string (word);
HASH_ENTRY entry;
if (is_new)
*is_new = 0;
for (entry = word_table[hash];
entry && strcmp (entry->word, word); entry = entry->next)
;
if (!entry)
{
size_t n = sizeof *entry + strlen (word);
entry = xmalloc (n);
strcpy (entry->word, word);
entry->veg_count = 0;
entry->spam_count = 0;
entry->hit_ref = next_hit_ref++;
entry->prob = 0;
entry->next = word_table[hash];
word_table[hash] = entry;
if (is_new)
*is_new = 1;
}
return entry;
}
static void
check_one_word ( const char *word, int left_anchored, int is_spam,
HIT_ARRAY ha)
{
size_t wordlen = strlen (word);
const char *p;
int n0, n1, n2, n3, n4, n5;
/* fprintf (stderr, "token `%s'\n", word); */
for (p=word; isdigit (*p); p++)
;
if (!*p || wordlen < 3)
return; /* only digits or less than 3 chars */
if (wordlen == 16 && word[6] == '-' && word[13] == '-')
return; /* very likely a message-id formatted like 16cpeB-0004HM-00 */
if (wordlen > 25 )
return; /* words longer than that are rare */
for (n0=n1=n2=n3=n4=n5=0, p=word; *p; p++)
{
if ( *p & 0x80)
n0++;
else if ( isupper (*p) )
n1++;
else if ( islower (*p) )
n2++;
else if ( isdigit (*p) )
n3++;
else if ( *p == '-' )
n4++;
else if ( *p == '.' )
n5++;
}
if ( n4 == wordlen)
return; /* Only dashes. */
/* try to figure meaningless identifiers */
if (n0)
; /* 8bit chars in name are okay */
else if ( n3 && n3 + n5 == wordlen && n5 == 3 )
; /* allow IP addresses */
else if ( !n5 && n1 > 3 && (n2 > 3 || n3 > 3) )
return; /* No dots, mixed uppercase with digits or lowercase. */
else if ( !n5 && n2 > 3 && (n1 > 3 || n3 > 3) )
return; /* No dots, mixed lowercase with digits or uppercase. */
else if ( wordlen > 8 && (3*n3) > (n1+n2))
return; /* long word with 3 times more digits than letters. */
if (ha)
{ /* we are in checking mode */
int is_new;
HASH_ENTRY e = store_word (word, &is_new);
if (ha->size <= e->hit_ref)
{
assert (e->hit_ref < next_hit_ref);
enlarge_hit_array (ha);
}
ha->hits[e->hit_ref]++;
}
else if (is_spam)
store_word (word, NULL)->spam_count++;
else
store_word (word, NULL)->veg_count++;
}
/* Parse a message and return the number of messages in case it is an
mbox message as indicated by IS_MBOX passed as true. */
static unsigned int
parse_message (const char *fname, FILE *fp, int is_spam, int is_mbox,
HIT_ARRAY ha)
{
int c;
char aword[MAX_WORDLENGTH+1];
int idx = 0;
int in_token = 0;
int left_anchored = 0;
int maybe_base64 = 0;
PUSHBACK pbbuf;
unsigned int msgcount = 0;
int count = 0;
memset (&pbbuf, 0, sizeof pbbuf);
while ( (c=next_char (fp, &pbbuf)) != EOF)
{
if ( ++count > 20000 )
{
count = 0;
YIELD;
}
again:
if (in_token)
{
if ((c & 0x80) || strchr (TOKENCHARS, c))
{
if (idx < MAX_WORDLENGTH)
aword[idx++] = c;
/* truncate a word and ignore truncated characters */
}
else
{ /* got a delimiter */
in_token = 0;
aword[idx] = 0;
if (maybe_base64)
{
if ( !strcasecmp (aword, "base64") )
pbbuf.state = 1;
else if ( !strcasecmp (aword, "quoted-printable") )
pbbuf.state = 101;
else
pbbuf.state = 0;
maybe_base64 = 0;
}
else if (is_mbox && left_anchored
&& !pbbuf.state && !strcmp (aword, "From"))
{
if (c != ' ')
{
pbbuf.nl_seen = (c == '\n');
goto again;
}
msgcount++;
}
else if (left_anchored
&& (!strcasecmp (aword, "Received")
|| !strcasecmp (aword, "Date")))
{
if (c != ':')
{
pbbuf.nl_seen = (c == '\n');
goto again;
}
do
{
while ( (c = next_char (fp, &pbbuf)) != '\n')
{
if (c == EOF)
goto leave;
}
}
while ( c == ' ' || c == '\t');
pbbuf.nl_seen = 1;
goto again;
}
else if (left_anchored
&& !strcasecmp (aword, "Content-Transfer-Encoding"))
{
if (c != ':')
{
pbbuf.nl_seen = (c == '\n');
goto again;
}
maybe_base64 = 1;
}
else if (c == '.' && idx && !(aword[idx-1] & 0x80)
&& isalnum (aword[idx-1]) )
{
/* Assume an IP address or a hostname if a dot is
followed by a letter or digit. */
c = next_char (fp, &pbbuf);
if ( !(c & 0x80) && isalnum (c) && idx < MAX_WORDLENGTH)
{
aword[idx++] = '.';
in_token = 1;
}
else
check_one_word (aword, left_anchored, is_spam, ha);
pbbuf.nl_seen = (c == '\n');
goto again;
}
#if 0
else if (c == '=')
{
/* Assume an QP encoded character if followed by an
hexdigit */
c = next_char (fp, &pbbuf);
if ( !(c & 0x80) && (isxdigit (c)) && idx < MAX_WORDLENGTH)
{
aword[idx++] = '=';
in_token = 1;
}
else
check_one_word (aword, left_anchored, is_spam, ha);
pbbuf.nl_seen = (c == '\n');
goto again;
}
#endif
else
check_one_word (aword, left_anchored, is_spam, ha);
}
}
else if ( (c & 0x80) || strchr (TOKENCHARS, c))
{
in_token = 1;
idx = 0;
aword[idx++] = c;
left_anchored = pbbuf.nl_seen;
}
pbbuf.nl_seen = (c == '\n');
}
leave:
if (ferror (fp))
die ("error reading `%s': %s\n", fname, strerror (errno));
msgcount++;
return msgcount;
}
static unsigned int
calc_prob (unsigned int g, unsigned int b,
unsigned int ngood, unsigned int nbad)
{
double prob_g, prob_b, prob;
/* (max .01 */
/* (min .99 (float (/ (min 1 (/ b nbad)) */
/* (+ (min 1 (/ g ngood)) */
/* (min 1 (/ b nbad))))))))) */
prob_g = (double)g / ngood;
if (prob_g > 1)
prob_g = 1;
prob_b = (double)b / ngood;
if (prob_b > 1)
prob_b = 1;
prob = prob_b / (prob_g + prob_b);
if (prob < .01)
prob = .01;
else if (prob > .99)
prob = .99;
return (unsigned int) (prob * 100);
}
static void
calc_probability (unsigned int ngood, unsigned int nbad)
{
int n;
HASH_ENTRY entry;
unsigned int g, b;
if (!ngood)
die ("no vegetarian mails available - stop\n");
if (!nbad)
die ("no spam mails available - stop\n");
for (n=0; n < hash_table_size; n++)
{
for (entry = word_table[n]; entry; entry = entry->next)
{
g = entry->veg_count * 2;
b = entry->spam_count;
if (g + b >= 5)
entry->prob = calc_prob (g, b, ngood, nbad);
}
}
}
static unsigned int
check_spam (unsigned int ngood, unsigned int nbad, HIT_ARRAY ha)
{
unsigned int n;
HASH_ENTRY entry;
unsigned int dist, min_dist;
struct {
HASH_ENTRY e;
unsigned int d;
double prob;
} st[MAX_WORDS];
int nst = 0;
int i;
double prod, inv_prod, taste;
for (i=0; i < MAX_WORDS; i++)
{
st[i].e = NULL;
st[i].d = 0;
}
min_dist = 100;
for (n=0; n < hash_table_size; n++)
{
for (entry = word_table[n]; entry; entry = entry->next)
{
if (entry->hit_ref && ha->hits[entry->hit_ref])
{
if (!entry->prob)
dist = 10; /* 50 - 40 */
else
dist = entry->prob < 50? (50 - entry->prob):(entry->prob - 50);
if (nst < MAX_WORDS)
{
st[nst].e = entry;
st[nst].d = dist;
st[nst].prob = entry->prob? (double)entry->prob/100 : 0.4;
if (dist < min_dist)
min_dist = dist;
nst++;
}
else if (dist > min_dist)
{
unsigned int tmp = 100;
int tmpidx = -1;
for (i=0; i < MAX_WORDS; i++)
{
if (st[i].d < tmp)
{
tmp = st[i].d;
tmpidx = i;
}
}
assert (tmpidx != -1);
st[tmpidx].e = entry;
st[tmpidx].d = dist;
st[tmpidx].prob = entry->prob? (double)entry->prob/100 : 0.4;
min_dist = 100;
for (i=0; i < MAX_WORDS; i++)
{
if (st[i].d < min_dist)
min_dist = dist;
}
}
}
}
}
/* ST has now the NST most intersting words */
if (!nst)
{
info ("not enough words - assuming goodness\n");
return 100;
}
if (verbose > 1)
{
for (i=0; i < nst; i++)
info ("prob %3.2f dist %3d for `%s'\n",
st[i].prob, st[i].d, st[i].e->word);
}
prod = 1;
for (i=0; i < nst; i++)
prod *= st[i].prob;
inv_prod = 1;
for (i=0; i < nst; i++)
inv_prod *= 1.0 - st[i].prob;
taste = prod / (prod + inv_prod);
if (verbose > 1)
info ("taste -> %u\n\n", (unsigned int)(taste * 100));
return (unsigned int)(taste * 100);
}
static void
reset_hits (HIT_ARRAY ha)
{
int i;
for (i=0; i < ha->size; i++)
ha->hits[i] = 0;
}
static void
write_table (unsigned int ngood, unsigned int nbad)
{
int n;
HASH_ENTRY entry;
printf ("#\t0\t0\t0\t%u\t%u\n", ngood, nbad);
for (n=0; n < hash_table_size; n++)
{
for (entry = word_table[n]; entry; entry = entry->next)
if (entry->prob)
printf ("%s\t%d\t%u\t%u\n", entry->word, entry->prob,
entry->veg_count, entry->spam_count);
}
}
static void
read_table (const char *fname,
unsigned int *ngood, unsigned int *nbad, unsigned int *nwords)
{
FILE *fp;
char line[MAX_WORDLENGTH + 100];
unsigned int lineno = 0;
char *p;
*nwords = 0;
fp = fopen (fname, "r");
if (!fp)
die ("can't open wordlist `%s': %s\n", fname, strerror (errno));
while ( fgets (line, sizeof line, fp) )
{
lineno++;
if (!*line) /* last line w/o LF? */
die ("incomplete line %u in `%s'\n", lineno, fname);
if (line[strlen (line)-1] != '\n')
die ("line %u in `%s' too long\n", lineno, fname);
line[strlen (line)-1] = 0;
if (!*line)
goto invalid_line;
p = strchr (line, '\t');
if (!p || p == line || (p-line) > MAX_WORDLENGTH )
goto invalid_line;
*p++ = 0;
if (lineno == 1)
{
if (sscanf (p, "%*u %*u %*u %u %u", ngood, nbad) < 2)
goto invalid_line;
}
else
{
HASH_ENTRY e;
unsigned int prob, g, b;
int is_new;
if (sscanf (p, "%u %u %u", &prob, &g, &b) < 3)
goto invalid_line;
if (prob > 99)
goto invalid_line;
e = store_word (line, &is_new);
if (!is_new)
die ("duplicate entry at line %u in `%s'\n", lineno, fname);
e->prob = prob? prob : 1;
e->veg_count = g;
e->spam_count = b;
++*nwords;
}
}
if (ferror (fp))
die ("error reading wordlist `%s' at line %u: %s\n",
fname, lineno, strerror (errno));
fclose (fp);
return;
invalid_line:
die ("invalid line %u in `%s'\n", lineno, fname);
}