/* $Cambridge: exim/exim-src/src/srs.c,v 1.8 2005/06/27 18:10:30 tom Exp $ */

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

/* SRS - Sender rewriting scheme support
  (C)2004 Miles Wilton <miles@mirtol.com>

  SRS Support Version: 1.0a

  License: GPL */

#include "exim.h"
#ifdef EXPERIMENTAL_SRS

#include <srs_alt.h>
#include "srs.h"

srs_t    *srs                   = NULL;
uschar   *srs_db_forward        = NULL;
uschar   *srs_db_reverse        = NULL;


/* srs_init just initialises libsrs and creates (if necessary)
   an srs object to use for all srs calls in this instance */

int eximsrs_init()
{
  uschar *list = srs_config;
  uschar secret_buf[SRS_MAX_SECRET_LENGTH];
  uschar *secret = NULL;
  uschar sbuf[4];
  uschar *sbufp;

  /* Check if this instance of Exim has not initialized SRS */
  if(srs == NULL)
  {
    int co = 0;
    int hashlen, maxage;
    BOOL usetimestamp, usehash;

    /* Copy config vars */
    hashlen = srs_hashlength;
    maxage = srs_maxage;
    usetimestamp = srs_usetimestamp;
    usehash = srs_usehash;

    /* Pass srs_config var (overrides new config vars) */
    co = 0;
    if(srs_config != NULL)
    {
      secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH);

      if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
        maxage = atoi(sbuf);

      if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
        hashlen = atoi(sbuf);

      if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
        usetimestamp = atoi(sbuf);

      if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
        usehash = atoi(sbuf);
    }

    if(srs_hashmin == -1)
      srs_hashmin = hashlen;

    /* First secret specified in secrets? */
    co = 0;
    list = srs_secrets;
    if(secret == NULL || *secret == '\0')
    {
      if((secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH)) == NULL)
      {
        log_write(0, LOG_MAIN | LOG_PANIC,
            "SRS Configuration Error: No secret specified");
        return DEFER;
      }
    }

    /* Check config */
    if(maxage < 0 || maxage > 365)
    {
      log_write(0, LOG_MAIN | LOG_PANIC,
          "SRS Configuration Error: Invalid maximum timestamp age");
      return DEFER;
    }
    if(hashlen < 1 || hashlen > 20 || srs_hashmin < 1 || srs_hashmin > 20)
    {
      log_write(0, LOG_MAIN | LOG_PANIC,
          "SRS Configuration Error: Invalid hash length");
      return DEFER;
    }

    if((srs = srs_open(secret, Ustrlen(secret), maxage, hashlen, srs_hashmin)) == NULL)
    {
      log_write(0, LOG_MAIN | LOG_PANIC,
          "Failed to allocate SRS memory");
      return DEFER;
    }

    srs_set_option(srs, SRS_OPTION_USETIMESTAMP, usetimestamp);
    srs_set_option(srs, SRS_OPTION_USEHASH, usehash);

    /* Extra secrets? */
    while((secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH)) != NULL)
        srs_add_secret(srs, secret, (Ustrlen(secret) > SRS_MAX_SECRET_LENGTH) ? SRS_MAX_SECRET_LENGTH :  Ustrlen(secret));

    DEBUG(D_any)
      debug_printf("SRS initialized\n");
  }

  return OK;
}


int eximsrs_done()
{
  if(srs != NULL)
    srs_close(srs);

  srs = NULL;

  return OK;
}


int eximsrs_forward(uschar **result, uschar *orig_sender, uschar *domain)
{
  char res[512];
  int n;

  if((n = srs_forward(srs, orig_sender, domain, res, sizeof(res))) & SRS_RESULT_FAIL)
  {
    DEBUG(D_any)
      debug_printf("srs_forward failed (%s, %s): %s\n", orig_sender, domain, srs_geterrormsg(n));
    return DEFER;
  }

  *result = string_copy(res);
  return OK;
}


int eximsrs_reverse(uschar **result, uschar *address)
{
  char res[512];
  int n;

  if((n = srs_reverse(srs, address, res, sizeof(res))) & SRS_RESULT_FAIL)
  {
    DEBUG(D_any)
      debug_printf("srs_reverse failed (%s): %s\n", address, srs_geterrormsg(n));
    if(n == SRS_RESULT_NOTSRS || n == SRS_RESULT_BADSRS)
      return DECLINE;
    if(n == SRS_RESULT_BADHASH || n == SRS_RESULT_BADTIMESTAMP || n == SRS_RESULT_TIMESTAMPEXPIRED)
      return FAIL;
    return DEFER;
  }

  *result = string_copy(res);
  return OK;
}


int eximsrs_db_set(BOOL reverse, uschar *srs_db)
{
  if(reverse)
    srs_db_reverse = (srs_db == NULL ? NULL : string_copy(srs_db));
  else
    srs_db_forward = (srs_db == NULL ? NULL : string_copy(srs_db));

  if(srs_set_db_functions(srs, (srs_db_forward ? eximsrs_db_insert : NULL),
                               (srs_db_reverse ? eximsrs_db_lookup : NULL)) & SRS_RESULT_FAIL)
    return DEFER;

  return OK;
}


srs_result eximsrs_db_insert(srs_t *srs, char *data, uint data_len, char *result, uint result_len)
{
  uschar *res;
  uschar buf[64];

  if(srs_db_forward == NULL)
    return SRS_RESULT_DBERROR;

  srs_db_address = string_copyn(data, data_len);
  if(srs_generate_unique_id(srs, srs_db_address, buf, 64) & SRS_RESULT_FAIL)
    return SRS_RESULT_DBERROR;

  srs_db_key = string_copyn(buf, 16);

  if((res = expand_string(srs_db_forward)) == NULL)
    return SRS_RESULT_DBERROR;

  if(result_len < 17)
    return SRS_RESULT_DBERROR;

  Ustrncpy(result, srs_db_key, result_len);

  return SRS_RESULT_OK;
}


srs_result eximsrs_db_lookup(srs_t *srs, char *data, uint data_len, char *result, uint result_len)
{
  uschar *res;

  if(srs_db_reverse == NULL)
    return SRS_RESULT_DBERROR;

  srs_db_key = string_copyn(data, data_len);
  if((res = expand_string(srs_db_reverse)) == NULL)
    return SRS_RESULT_DBERROR;

  if(Ustrlen(res) >= result_len)
    return SRS_RESULT_ADDRESSTOOLONG;

  strncpy(result, res, result_len);

  return SRS_RESULT_OK;
}


#endif