path: root/src/spam.c

/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/*
 * Copyright (c) The Exim Maintainers 2016 - 2022
 * Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003 - 2015
 * License: GPL
 */

/* Code for calling spamassassin's spamd. Called from acl.c. */

#include "exim.h"
#ifdef WITH_CONTENT_SCAN
#include "spam.h"

uschar spam_score_buffer[16];
uschar spam_score_int_buffer[16];
uschar spam_bar_buffer[128];
uschar spam_action_buffer[32];
uschar spam_report_buffer[32600];
uschar * prev_user_name = NULL;
int spam_ok = 0;
int spam_rc = 0;
uschar *prev_spamd_address_work = NULL;

static const uschar * loglabel = US"spam acl condition:";


static int
spamd_param_init(spamd_address_container *spamd)
{
/* default spamd server weight, time and priority value */
spamd->is_rspamd = FALSE;
spamd->is_failed = FALSE;
spamd->weight = SPAMD_WEIGHT;
spamd->timeout = SPAMD_TIMEOUT;
spamd->retry = 0;
spamd->priority = SPAMD_PRIORITY;
return 0;
}


static int
spamd_param(const uschar * param, spamd_address_container * spamd)
{
static int timesinceday = -1;
const uschar * s;
const uschar * name;

/*XXX more clever parsing could discard embedded spaces? */

if (sscanf(CCS param, "pri=%u", &spamd->priority))
  return 0; /* OK */

if (sscanf(CCS param, "weight=%u", &spamd->weight))
  {
  if (spamd->weight == 0) /* this server disabled: skip it */
    return 1;
  return 0; /* OK */
  }

if (Ustrncmp(param, "time=", 5) == 0)
  {
  unsigned int start_h = 0, start_m = 0, start_s = 0;
  unsigned int end_h = 24, end_m = 0, end_s = 0;
  unsigned int time_start, time_end;
  const uschar * end_string;

  name = US"time";
  s = param+5;
  if ((end_string = Ustrchr(s, '-')))
    {
    end_string++;
    if (  sscanf(CS end_string, "%u.%u.%u", &end_h,   &end_m,   &end_s)   == 0
       || sscanf(CS s,          "%u.%u.%u", &start_h, &start_m, &start_s) == 0
       )
      goto badval;
    }
  else
    goto badval;

  if (timesinceday < 0)
    {
    time_t now = time(NULL);
    struct tm *tmp = localtime(&now);
    timesinceday = tmp->tm_hour*3600 + tmp->tm_min*60 + tmp->tm_sec;
    }

  time_start = start_h*3600 + start_m*60 + start_s;
  time_end = end_h*3600 + end_m*60 + end_s;

  if (timesinceday < time_start || timesinceday >= time_end)
    return 1; /* skip spamd server */

  return 0; /* OK */
  }

if (Ustrcmp(param, "variant=rspamd") == 0)
  {
  spamd->is_rspamd = TRUE;
  return 0;
  }

if (Ustrncmp(param, "tmo=", 4) == 0)
  {
  int sec = readconf_readtime((s = param+4), '\0', FALSE);
  name = US"timeout";
  if (sec < 0)
    goto badval;
  spamd->timeout = sec;
  return 0;
  }

if (Ustrncmp(param, "retry=", 6) == 0)
  {
  int sec = readconf_readtime((s = param+6), '\0', FALSE);
  name = US"retry";
  if (sec < 0)
    goto badval;
  spamd->retry = sec;
  return 0;
  }

log_write(0, LOG_MAIN, "%s warning - invalid spamd parameter: '%s'",
  loglabel, param);
return -1; /* syntax error */

badval:
  log_write(0, LOG_MAIN,
    "%s warning - invalid spamd %s value: '%s'", loglabel, name, s);
  return -1; /* syntax error */
}


static int
spamd_get_server(spamd_address_container ** spamds, int num_servers)
{
unsigned int i;
spamd_address_container * sd;
long weights;
unsigned pri;

/* speedup, if we have only 1 server */
if (num_servers == 1)
  return (spamds[0]->is_failed ? -1 : 0);

/* scan for highest pri */
for (pri = 0, i = 0; i < num_servers; i++)
  {
  sd = spamds[i];
  if (!sd->is_failed && sd->priority > pri) pri = sd->priority;
  }

/* get sum of weights */
for (weights = 0, i = 0; i < num_servers; i++)
  {
  sd = spamds[i];
  if (!sd->is_failed && sd->priority == pri) weights += sd->weight;
  }
if (weights == 0)	/* all servers failed */
  return -1;

for (long rnd = random_number(weights), i = 0; i < num_servers; i++)
  {
  sd = spamds[i];
  if (!sd->is_failed && sd->priority == pri)
    if ((rnd -= sd->weight) < 0)
      return i;
  }

log_write(0, LOG_MAIN|LOG_PANIC,
  "%s unknown error (memory/cpu corruption?)", loglabel);
return -1;
}


int
spam(const uschar **listptr)
{
int sep = 0;
const uschar *list = *listptr;
uschar *user_name;
unsigned long mbox_size;
FILE *mbox_file;
client_conn_ctx spamd_cctx = {.sock = -1};
uschar spamd_buffer[32600];
int i, j, offset, result;
uschar spamd_version[8];
uschar spamd_short_result[8];
uschar spamd_score_char;
double spamd_threshold, spamd_score, spamd_reject_score;
int spamd_report_offset;
uschar *p,*q;
int override = 0;
time_t start;
size_t read, wrote;
uschar *spamd_address_work;
spamd_address_container * sd;

/* stop compiler warning */
result = 0;

/* find the username from the option list */
if (!(user_name = string_nextinlist(&list, &sep, NULL, 0)))
  {
  /* no username given, this means no scanning should be done */
  return FAIL;
  }

/* if username is "0" or "false", do not scan */
if (Ustrcmp(user_name, "0") == 0 || strcmpic(user_name, US"false") == 0)
  return FAIL;

/* if there is an additional option, check if it is "true" */
if (strcmpic(list,US"true") == 0)
  /* in that case, always return true later */
  override = 1;

/* expand spamd_address if needed */
if (*spamd_address != '$')
  spamd_address_work = spamd_address;
else if (!(spamd_address_work = expand_string(spamd_address)))
  {
  log_write(0, LOG_MAIN|LOG_PANIC,
    "%s spamd_address starts with $, but expansion failed: %s",
    loglabel, expand_string_message);
  return DEFER;
  }

DEBUG(D_acl) debug_printf_indent("spamd: addrlist '%s'\n", spamd_address_work);

/* check if previous spamd_address was expanded and has changed. dump cached results if so */
if (  spam_ok
   && prev_spamd_address_work != NULL
   && Ustrcmp(prev_spamd_address_work, spamd_address_work) != 0
   )
  spam_ok = 0;

/* if we scanned for this username last time, just return */
if (spam_ok && Ustrcmp(prev_user_name, user_name) == 0)
  return override ? OK : spam_rc;

/* make sure the eml mbox file is spooled up */

if (!(mbox_file = spool_mbox(&mbox_size, NULL, NULL)))
  {								/* error while spooling */
  log_write(0, LOG_MAIN|LOG_PANIC,
	 "%s error while creating mbox spool file", loglabel);
  return DEFER;
  }

start = time(NULL);

  {
  int num_servers = 0;
  int current_server;
  uschar * address;
  const uschar * spamd_address_list_ptr = spamd_address_work;
  spamd_address_container * spamd_address_vector[32];

  /* Check how many spamd servers we have
     and register their addresses */
  sep = 0;				/* default colon-sep */
  while ((address = string_nextinlist(&spamd_address_list_ptr, &sep, NULL, 0)))
    {
    const uschar * sublist;
    int sublist_sep = -(int)' ';	/* default space-sep */
    unsigned args;
    uschar * s;

    DEBUG(D_acl) debug_printf_indent("spamd: addr entry '%s'\n", address);
    sd = store_get(sizeof(spamd_address_container), GET_UNTAINTED);

    for (sublist = address, args = 0, spamd_param_init(sd);
	 (s = string_nextinlist(&sublist, &sublist_sep, NULL, 0));
	 args++
	 )
      {
	DEBUG(D_acl) debug_printf_indent("spamd:  addr parm '%s'\n", s);
	switch (args)
	{
	case 0:   sd->hostspec = s;
		  if (*s == '/') args++;	/* local; no port */
		  break;
	case 1:   sd->hostspec = string_sprintf("%s %s", sd->hostspec, s);
		  break;
	default:  spamd_param(s, sd);
		  break;
	}
      }
    if (args < 2)
      {
      log_write(0, LOG_MAIN,
	"%s warning - invalid spamd address: '%s'", loglabel, address);
      continue;
      }

    spamd_address_vector[num_servers] = sd;
    if (++num_servers > 31)
      break;
    }

  /* check if we have at least one server */
  if (!num_servers)
    {
    log_write(0, LOG_MAIN|LOG_PANIC,
       "%s no useable spamd server addresses in spamd_address configuration option.",
       loglabel);
    goto defer;
    }

  current_server = spamd_get_server(spamd_address_vector, num_servers);
  sd = spamd_address_vector[current_server];
  for(;;)
    {
    uschar * errstr;

    DEBUG(D_acl) debug_printf_indent("spamd: trying server %s\n", sd->hostspec);

    for (;;)
      {
      /*XXX could potentially use TFO early-data here */
      if (  (spamd_cctx.sock = ip_streamsocket(sd->hostspec, &errstr, 5, NULL)) >= 0
         || sd->retry <= 0
	 )
	break;
      DEBUG(D_acl) debug_printf_indent("spamd: server %s: retry conn\n", sd->hostspec);
      while (sd->retry > 0) sd->retry = sleep(sd->retry);
      }
    if (spamd_cctx.sock >= 0)
      break;

    log_write(0, LOG_MAIN, "%s spamd: %s", loglabel, errstr);
    sd->is_failed = TRUE;

    current_server = spamd_get_server(spamd_address_vector, num_servers);
    if (current_server < 0)
      {
      log_write(0, LOG_MAIN|LOG_PANIC, "%s all spamd servers failed", loglabel);
      goto defer;
      }
    sd = spamd_address_vector[current_server];
    }
  }

(void)fcntl(spamd_cctx.sock, F_SETFL, O_NONBLOCK);
/* now we are connected to spamd on spamd_cctx.sock */
if (sd->is_rspamd)
  {
  gstring * req_str;
  const uschar * s;

  req_str = string_append(NULL, 8,
    "CHECK RSPAMC/1.3\r\nContent-length: ", string_sprintf("%lu\r\n", mbox_size),
    "Queue-Id: ", message_id,
    "\r\nFrom: <", sender_address,
    ">\r\nRecipient-Number: ", string_sprintf("%d\r\n", recipients_count));

  for (int i = 0; i < recipients_count; i++)
    req_str = string_append(req_str, 3,
      "Rcpt: <", recipients_list[i].address, ">\r\n");
  if ((s = expand_string(US"$sender_helo_name")) && *s)
    req_str = string_append(req_str, 3, "Helo: ", s, "\r\n");
  if ((s = expand_string(US"$sender_host_name")) && *s)
    req_str = string_append(req_str, 3, "Hostname: ", s, "\r\n");
  if (sender_host_address)
    req_str = string_append(req_str, 3, "IP: ", sender_host_address, "\r\n");
  if ((s = expand_string(US"$authenticated_id")) && *s)
    req_str = string_append(req_str, 3, "User: ", s, "\r\n");
  req_str = string_catn(req_str, US"\r\n", 2);
  wrote = send(spamd_cctx.sock, req_str->s, req_str->ptr, 0);
  }
else
  {				/* spamassassin variant */
  int n;
  uschar * s = string_sprintf(
	  "REPORT SPAMC/1.2\r\nUser: %s\r\nContent-length: %ld\r\n\r\n%n",
	  user_name, mbox_size, &n);
  /* send our request */
  wrote = send(spamd_cctx.sock, s, n, 0);
  }

if (wrote == -1)
  {
  (void)close(spamd_cctx.sock);
  log_write(0, LOG_MAIN|LOG_PANIC,
       "%s spamd %s send failed: %s", loglabel, callout_address, strerror(errno));
  goto defer;
  }

/* now send the file */
/* spamd sometimes accepts connections but doesn't read data off the connection.
We make the file descriptor non-blocking so that the write will only write
sufficient data without blocking and we poll the descriptor to make sure that we
can write without blocking.  Short writes are gracefully handled and if the
whole transaction takes too long it is aborted.

Note: poll() is not supported in OSX 10.2 and is reported to be broken in more
      recent versions (up to 10.4). Workaround using select() removed 2021/11 (jgh).
 */
#ifdef NO_POLL_H
# error Need poll(2) support
#endif

(void)fcntl(spamd_cctx.sock, F_SETFL, O_NONBLOCK);
do
  {
  read = fread(spamd_buffer,1,sizeof(spamd_buffer),mbox_file);
  if (read > 0)
    {
    offset = 0;
again:
    result = poll_one_fd(spamd_cctx.sock, POLLOUT, 1000);
    if (result == -1 && errno == EINTR)
      goto again;
    else if (result < 1)
      {
      if (result == -1)
	log_write(0, LOG_MAIN|LOG_PANIC,
	  "%s %s on spamd %s socket", loglabel, callout_address, strerror(errno));
      else
	{
	if (time(NULL) - start < sd->timeout)
	  goto again;
	log_write(0, LOG_MAIN|LOG_PANIC,
	  "%s timed out writing spamd %s, socket", loglabel, callout_address);
	}
      (void)close(spamd_cctx.sock);
      goto defer;
      }

    wrote = send(spamd_cctx.sock,spamd_buffer + offset,read - offset,0);
    if (wrote == -1)
      {
      log_write(0, LOG_MAIN|LOG_PANIC,
	  "%s %s on spamd %s socket", loglabel, callout_address, strerror(errno));
      (void)close(spamd_cctx.sock);
      goto defer;
      }
    if (offset + wrote != read)
      {
      offset += wrote;
      goto again;
      }
    }
  }
while (!feof(mbox_file) && !ferror(mbox_file));

if (ferror(mbox_file))
  {
  log_write(0, LOG_MAIN|LOG_PANIC,
    "%s error reading spool file: %s", loglabel, strerror(errno));
  (void)close(spamd_cctx.sock);
  goto defer;
  }

(void)fclose(mbox_file);

/* we're done sending, close socket for writing */
if (!sd->is_rspamd)
  shutdown(spamd_cctx.sock,SHUT_WR);

/* read spamd response using what's left of the timeout.  */
memset(spamd_buffer, 0, sizeof(spamd_buffer));
offset = 0;
while ((i = ip_recv(&spamd_cctx,
		   spamd_buffer + offset,
		   sizeof(spamd_buffer) - offset - 1,
		   sd->timeout + start)) > 0)
  offset += i;
spamd_buffer[offset] = '\0';	/* guard byte */

/* error handling */
if (i <= 0 && errno != 0)
  {
  log_write(0, LOG_MAIN|LOG_PANIC,
       "%s error reading from spamd %s, socket: %s", loglabel, callout_address, strerror(errno));
  (void)close(spamd_cctx.sock);
  return DEFER;
  }

/* reading done */
(void)close(spamd_cctx.sock);

if (sd->is_rspamd)
  {				/* rspamd variant of reply */
  int r;
  if (  (r = sscanf(CS spamd_buffer,
	  "RSPAMD/%7s 0 EX_OK\r\nMetric: default; %7s %lf / %lf / %lf\r\n%n",
	  spamd_version, spamd_short_result, &spamd_score, &spamd_threshold,
	  &spamd_reject_score, &spamd_report_offset)) != 5
     || spamd_report_offset >= offset		/* verify within buffer */
     )
    {
    log_write(0, LOG_MAIN|LOG_PANIC,
	      "%s cannot parse spamd %s, output: %d", loglabel, callout_address, r);
    return DEFER;
    }
  /* now parse action */
  p = &spamd_buffer[spamd_report_offset];

  if (Ustrncmp(p, "Action: ", sizeof("Action: ") - 1) == 0)
    {
    p += sizeof("Action: ") - 1;
    q = &spam_action_buffer[0];
    while (*p && *p != '\r' && (q - spam_action_buffer) < sizeof(spam_action_buffer) - 1)
      *q++ = *p++;
    *q = '\0';
    }
  }
else
  {				/* spamassassin */
  /* dig in the spamd output and put the report in a multiline header,
  if requested */
  if (sscanf(CS spamd_buffer,
       "SPAMD/%7s 0 EX_OK\r\nContent-length: %*u\r\n\r\n%lf/%lf\r\n%n",
       spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3)
    {
      /* try to fall back to pre-2.50 spamd output */
      if (sscanf(CS spamd_buffer,
	   "SPAMD/%7s 0 EX_OK\r\nSpam: %*s ; %lf / %lf\r\n\r\n%n",
	   spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3)
	{
	log_write(0, LOG_MAIN|LOG_PANIC,
		  "%s cannot parse spamd %s output", loglabel, callout_address);
	return DEFER;
	}
    }

  Ustrcpy(spam_action_buffer,
    spamd_score >= spamd_threshold ? US"reject" : US"no action");
  }

/* Create report. Since this is a multiline string,
we must hack it into shape first */
p = &spamd_buffer[spamd_report_offset];
q = spam_report_buffer;
while (*p != '\0')
  {
  /* skip \r */
  if (*p == '\r')
    {
    p++;
    continue;
    }
  *q++ = *p;
  if (*p++ == '\n')
    {
    /* add an extra space after the newline to ensure
    that it is treated as a header continuation line */
    *q++ = ' ';
    }
  }
/* NULL-terminate */
*q-- = '\0';
/* cut off trailing leftovers */
while (*q <= ' ')
  *q-- = '\0';

spam_report = spam_report_buffer;
spam_action = spam_action_buffer;

/* create spam bar */
spamd_score_char = spamd_score > 0 ? '+' : '-';
j = abs((int)(spamd_score));
i = 0;
if (j != 0)
  while ((i < j) && (i <= MAX_SPAM_BAR_CHARS))
     spam_bar_buffer[i++] = spamd_score_char;
else
  {
  spam_bar_buffer[0] = '/';
  i = 1;
  }
spam_bar_buffer[i] = '\0';
spam_bar = spam_bar_buffer;

/* create "float" spam score */
(void)string_format(spam_score_buffer, sizeof(spam_score_buffer),
	"%.1f", spamd_score);
spam_score = spam_score_buffer;

/* create "int" spam score */
j = (int)((spamd_score + 0.001)*10);
(void)string_format(spam_score_int_buffer, sizeof(spam_score_int_buffer),
	"%d", j);
spam_score_int = spam_score_int_buffer;

/* compare threshold against score */
spam_rc = spamd_score >= spamd_threshold
  ? OK	/* spam as determined by user's threshold */
  : FAIL;	/* not spam */

/* remember expanded spamd_address if needed */
if (spamd_address_work != spamd_address)
  prev_spamd_address_work = string_copy(spamd_address_work);

/* remember user name and "been here" for it */
prev_user_name = user_name;
spam_ok = 1;

return override
  ? OK		/* always return OK, no matter what the score */
  : spam_rc;

defer:
  (void)fclose(mbox_file);
  return DEFER;
}

#endif
/* vi: aw ai sw=2
*/