[exim.git] / src / src / dmarc.c

/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/
/* Experimental DMARC support.
   Copyright (c) Todd Lyons <tlyons@exim.org> 2012, 2013
   License: GPL */

/* Portions Copyright (c) 2012, 2013, The Trusted Domain Project;
   All rights reserved, licensed for use per LICENSE.opendmarc. */

/* Code for calling dmarc checks via libopendmarc. Called from acl.c. */

#include "exim.h"
#ifdef EXPERIMENTAL_DMARC
#if !defined EXPERIMENTAL_SPF
#error SPF must also be enabled for DMARC
#elif defined DISABLE_DKIM
#error DKIM must also be enabled for DMARC
#else

#include "functions.h"
#include "dmarc.h"
#include "pdkim/pdkim.h"

OPENDMARC_LIB_T     dmarc_ctx;
DMARC_POLICY_T     *dmarc_pctx = NULL;
OPENDMARC_STATUS_T  libdm_status, action, dmarc_policy;
OPENDMARC_STATUS_T  da, sa, action;
BOOL dmarc_abort  = FALSE;
uschar *dmarc_pass_fail = US"skipped";
extern pdkim_signature  *dkim_signatures;
header_line *from_header   = NULL;
extern SPF_response_t   *spf_response;
int dmarc_spf_ares_result  = 0;
uschar *spf_sender_domain  = NULL;
uschar *spf_human_readable = NULL;
u_char *header_from_sender = NULL;
int history_file_status    = DMARC_HIST_OK;
uschar *dkim_history_buffer= NULL;

/* Accept an error_block struct, initialize if empty, parse to the
 * end, and append the two strings passed to it.  Used for adding
 * variable amounts of value:pair data to the forensic emails. */

static error_block *
add_to_eblock(error_block *eblock, uschar *t1, uschar *t2)
{
  error_block *eb = malloc(sizeof(error_block));
  if (eblock == NULL)
    eblock = eb;
  else
  {
    /* Find the end of the eblock struct and point it at eb */
    error_block *tmp = eblock;
    while(tmp->next != NULL)
      tmp = tmp->next;
    tmp->next = eb;
  }
  eb->text1 = t1;
  eb->text2 = t2;
  eb->next  = NULL;
  return eblock;
}

/* dmarc_init sets up a context that can be re-used for several
   messages on the same SMTP connection (that come from the
   same host with the same HELO string) */

int dmarc_init()
{
  int *netmask   = NULL;   /* Ignored */
  int is_ipv6    = 0;
  char *tld_file = (dmarc_tld_file == NULL) ?
                   "/etc/exim/opendmarc.tlds" :
                   (char *)dmarc_tld_file;

  /* Set some sane defaults.  Also clears previous results when
   * multiple messages in one connection. */
  dmarc_pctx         = NULL;
  dmarc_status       = US"none";
  dmarc_abort        = FALSE;
  dmarc_pass_fail    = US"skipped";
  dmarc_used_domain  = US"";
  header_from_sender = NULL;
  spf_sender_domain  = NULL;
  spf_human_readable = NULL;

  /* ACLs have "control=dmarc_disable_verify" */
  if (dmarc_disable_verify == TRUE)
    return OK;

  (void) memset(&dmarc_ctx, '\0', sizeof dmarc_ctx);
  dmarc_ctx.nscount = 0;
  libdm_status = opendmarc_policy_library_init(&dmarc_ctx);
  if (libdm_status != DMARC_PARSE_OKAY)
  {
    log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to init library: %s",
                         opendmarc_policy_status_to_str(libdm_status));
    dmarc_abort = TRUE;
  }
  if (dmarc_tld_file == NULL)
    dmarc_abort = TRUE;
  else if (opendmarc_tld_read_file(tld_file, NULL, NULL, NULL))
  {
    log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d",
                         tld_file, errno);
    dmarc_abort = TRUE;
  }
  if (sender_host_address == NULL)
    dmarc_abort = TRUE;
  /* This catches locally originated email and startup errors above. */
  if ( dmarc_abort == FALSE )
  {
    is_ipv6 = string_is_ip_address(sender_host_address, netmask);
    is_ipv6 = (is_ipv6 == 6) ? TRUE :
              (is_ipv6 == 4) ? FALSE : FALSE;
    dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6);
    if (dmarc_pctx == NULL )
    {
      log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure creating policy context: ip=%s",
                                       sender_host_address);
      dmarc_abort = TRUE;
    }
  }

  return OK;
}


/* dmarc_store_data stores the header data so that subsequent
 * dmarc_process can access the data */

int dmarc_store_data(header_line *hdr) {
  /* No debug output because would change every test debug output */
  if (dmarc_disable_verify != TRUE)
    from_header = hdr;
  return OK;
}


/* dmarc_process adds the envelope sender address to the existing
   context (if any), retrieves the result, sets up expansion
   strings and evaluates the condition outcome. */

int dmarc_process() {
    int sr, origin;             /* used in SPF section */
    int dmarc_spf_result  = 0;  /* stores spf into dmarc conn ctx */
    pdkim_signature *sig  = NULL;
    BOOL has_dmarc_record = TRUE;
    u_char **ruf; /* forensic report addressees, if called for */

  /* ACLs have "control=dmarc_disable_verify" */
  if (dmarc_disable_verify == TRUE)
  {
    dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);
    return OK;
  }

  /* Store the header From: sender domain for this part of DMARC.
   * If there is no from_header struct, then it's likely this message
   * is locally generated and relying on fixups to add it.  Just skip
   * the entire DMARC system if we can't find a From: header....or if
   * there was a previous error.
   */
  if (from_header == NULL || dmarc_abort == TRUE)
    dmarc_abort = TRUE;
  else
  {
    /* I strongly encourage anybody who can make this better to contact me directly!
     * <cannonball> Is this an insane way to extract the email address from the From: header?
     * <jgh_hm> it's sure a horrid layer-crossing....
     * <cannonball> I'm not denying that :-/
     * <jgh_hm> there may well be no better though
     */
    header_from_sender = expand_string(
                           string_sprintf("${domain:${extract{1}{:}{${addresses:%s}}}}",
                             from_header->text) );
    /* The opendmarc library extracts the domain from the email address, but
     * only try to store it if it's not empty.  Otherwise, skip out of DMARC. */
    if (strcmp( CCS header_from_sender, "") == 0)
      dmarc_abort = TRUE;
    libdm_status = (dmarc_abort == TRUE) ?
                   DMARC_PARSE_OKAY :
                   opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
    if (libdm_status != DMARC_PARSE_OKAY)
    {
      log_write(0, LOG_MAIN|LOG_PANIC, "failure to store header From: in DMARC: %s, header was '%s'",
                           opendmarc_policy_status_to_str(libdm_status), from_header->text);
      dmarc_abort = TRUE;
    }
  }

  /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
   * instead do this in the ACLs.  */
  if (dmarc_abort == FALSE && sender_host_authenticated == NULL)
  {
    /* Use the envelope sender domain for this part of DMARC */
    spf_sender_domain = expand_string(US"$sender_address_domain");
    if ( spf_response == NULL )
    {
      /* No spf data means null envelope sender so generate a domain name
       * from the sender_helo_name  */
      if (spf_sender_domain == NULL)
      {
        spf_sender_domain = sender_helo_name;
        log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
                               spf_sender_domain);
        DEBUG(D_receive)
          debug_printf("DMARC using synthesized SPF sender domain = %s\n", spf_sender_domain);
      }
      dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
      dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
      origin = DMARC_POLICY_SPF_ORIGIN_HELO;
      spf_human_readable = US"";
    }
    else
    {
      sr = spf_response->result;
      dmarc_spf_result = (sr == SPF_RESULT_NEUTRAL)  ? DMARC_POLICY_SPF_OUTCOME_NONE :
                         (sr == SPF_RESULT_PASS)     ? DMARC_POLICY_SPF_OUTCOME_PASS :
                         (sr == SPF_RESULT_FAIL)     ? DMARC_POLICY_SPF_OUTCOME_FAIL :
                         (sr == SPF_RESULT_SOFTFAIL) ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
                         DMARC_POLICY_SPF_OUTCOME_NONE;
      dmarc_spf_ares_result = (sr == SPF_RESULT_NEUTRAL)   ? ARES_RESULT_NEUTRAL :
                              (sr == SPF_RESULT_PASS)      ? ARES_RESULT_PASS :
                              (sr == SPF_RESULT_FAIL)      ? ARES_RESULT_FAIL :
                              (sr == SPF_RESULT_SOFTFAIL)  ? ARES_RESULT_SOFTFAIL :
                              (sr == SPF_RESULT_NONE)      ? ARES_RESULT_NONE :
                              (sr == SPF_RESULT_TEMPERROR) ? ARES_RESULT_TEMPERROR :
                              (sr == SPF_RESULT_PERMERROR) ? ARES_RESULT_PERMERROR :
                              ARES_RESULT_UNKNOWN;
      origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
      spf_human_readable = (uschar *)spf_response->header_comment;
      DEBUG(D_receive)
        debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
    }
    if (strcmp( CCS spf_sender_domain, "") == 0)
      dmarc_abort = TRUE;
    if (dmarc_abort == FALSE)
    {
      libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
                                                dmarc_spf_result, origin, spf_human_readable);
      if (libdm_status != DMARC_PARSE_OKAY)
        log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
                             opendmarc_policy_status_to_str(libdm_status));
    }

    /* Now we cycle through the dkim signature results and put into
     * the opendmarc context, further building the DMARC reply.  */
    sig = dkim_signatures;
    dkim_history_buffer = US"";
    while (sig != NULL)
    {
      int dkim_result, dkim_ares_result, vs, ves;
      vs  = sig->verify_status;
      ves = sig->verify_ext_status;
      dkim_result = ( vs == PDKIM_VERIFY_PASS ) ? DMARC_POLICY_DKIM_OUTCOME_PASS :
                    ( vs == PDKIM_VERIFY_FAIL ) ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
                    ( vs == PDKIM_VERIFY_INVALID ) ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
                    DMARC_POLICY_DKIM_OUTCOME_NONE;
      libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, (uschar *)sig->domain,
                                                 dkim_result, US"");
      DEBUG(D_receive)
        debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
      if (libdm_status != DMARC_PARSE_OKAY)
        log_write(0, LOG_MAIN|LOG_PANIC, "failure to store dkim (%s) for DMARC: %s",
                             sig->domain, opendmarc_policy_status_to_str(libdm_status));

      dkim_ares_result = ( vs == PDKIM_VERIFY_PASS )    ? ARES_RESULT_PASS :
                              ( vs == PDKIM_VERIFY_FAIL )    ? ARES_RESULT_FAIL :
                              ( vs == PDKIM_VERIFY_NONE )    ? ARES_RESULT_NONE :
                              ( vs == PDKIM_VERIFY_INVALID ) ?
                           ( ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
                             ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE        ? ARES_RESULT_PERMERROR :
                             ves == PDKIM_VERIFY_INVALID_PUBKEY_PARSING     ? ARES_RESULT_PERMERROR :
                             ARES_RESULT_UNKNOWN ) :
                          ARES_RESULT_UNKNOWN;
      dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
                                                             sig->domain, dkim_ares_result);
      sig = sig->next;
    }
    libdm_status = opendmarc_policy_query_dmarc(dmarc_pctx, US"");
    switch (libdm_status)
    {
      case DMARC_DNS_ERROR_NXDOMAIN:
      case DMARC_DNS_ERROR_NO_RECORD:
        DEBUG(D_receive)
          debug_printf("DMARC no record found for %s\n", header_from_sender);
        has_dmarc_record = FALSE;
        break;
      case DMARC_PARSE_OKAY:
        DEBUG(D_receive)
          debug_printf("DMARC record found for %s\n", header_from_sender);
        break;
      case DMARC_PARSE_ERROR_BAD_VALUE:
        DEBUG(D_receive)
          debug_printf("DMARC record parse error for %s\n", header_from_sender);
        has_dmarc_record = FALSE;
        break;
      default:
        /* everything else, skip dmarc */
        DEBUG(D_receive)
          debug_printf("DMARC skipping (%d), unsure what to do with %s",
                        libdm_status, from_header->text);
        has_dmarc_record = FALSE;
        break;
    }
    /* Can't use exim's string manipulation functions so allocate memory
     * for libopendmarc using its max hostname length definition. */
    uschar *dmarc_domain = (uschar *)calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar));
    libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx, dmarc_domain,
                                                          DMARC_MAXHOSTNAMELEN-1);
    dmarc_used_domain = string_copy(dmarc_domain);
    free(dmarc_domain);
    if (libdm_status != DMARC_PARSE_OKAY)
    {
      log_write(0, LOG_MAIN|LOG_PANIC, "failure to read domainname used for DMARC lookup: %s",
                                       opendmarc_policy_status_to_str(libdm_status));
    }
    libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
    dmarc_policy = libdm_status;
    switch(libdm_status)
    {
      case DMARC_POLICY_ABSENT:     /* No DMARC record found */
        dmarc_status = US"norecord";
        dmarc_pass_fail = US"temperror";
        dmarc_status_text = US"No DMARC record";
        action = DMARC_RESULT_ACCEPT;
        break;
      case DMARC_FROM_DOMAIN_ABSENT:    /* No From: domain */
        dmarc_status = US"nofrom";
        dmarc_pass_fail = US"temperror";
        dmarc_status_text = US"No From: domain found";
        action = DMARC_RESULT_ACCEPT;
        break;
      case DMARC_POLICY_NONE:       /* Accept and report */
        dmarc_status = US"none";
        dmarc_pass_fail = US"none";
        dmarc_status_text = US"None, Accept";
        action = DMARC_RESULT_ACCEPT;
        break;
      case DMARC_POLICY_PASS:       /* Explicit accept */
        dmarc_status = US"accept";
        dmarc_pass_fail = US"pass";
        dmarc_status_text = US"Accept";
        action = DMARC_RESULT_ACCEPT;
        break;
      case DMARC_POLICY_REJECT:       /* Explicit reject */
        dmarc_status = US"reject";
        dmarc_pass_fail = US"fail";
        dmarc_status_text = US"Reject";
        action = DMARC_RESULT_REJECT;
        break;
      case DMARC_POLICY_QUARANTINE:       /* Explicit quarantine */
        dmarc_status = US"quarantine";
        dmarc_pass_fail = US"fail";
        dmarc_status_text = US"Quarantine";
        action = DMARC_RESULT_QUARANTINE;
        break;
      default:
        dmarc_status = US"temperror";
        dmarc_pass_fail = US"temperror";
        dmarc_status_text = US"Internal Policy Error";
        action = DMARC_RESULT_TEMPFAIL;
        break;
    }

    libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
    if (libdm_status != DMARC_PARSE_OKAY)
    {
      log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
                                       opendmarc_policy_status_to_str(libdm_status));
    }

    if (has_dmarc_record == TRUE)
    {
      log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
                             "spf_align=%s dkim_align=%s enforcement='%s'",
                             spf_sender_domain, dmarc_used_domain,
                             (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?"yes":"no",
                             (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?"yes":"no",
                             dmarc_status_text);
      history_file_status = dmarc_write_history_file();
      /* Now get the forensic reporting addresses, if any */
      ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
      dmarc_send_forensic_report(ruf);
    }
  }

  /* set some global variables here */
  dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);

  /* shut down libopendmarc */
  if ( dmarc_pctx != NULL )
    (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
  if ( dmarc_disable_verify == FALSE )
    (void) opendmarc_policy_library_shutdown(&dmarc_ctx);

  return OK;
}

int dmarc_write_history_file()
{
  static int history_file_fd;
  ssize_t written_len;
  int tmp_ans;
  u_char **rua; /* aggregate report addressees */
  uschar *history_buffer = NULL;

  if (dmarc_history_file == NULL)
    return DMARC_HIST_DISABLED;
  history_file_fd = log_create(dmarc_history_file);

  if (history_file_fd < 0)
  {
    log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
                             dmarc_history_file);
    return DMARC_HIST_FILE_ERR;
  }

  /* Generate the contents of the history file */
  history_buffer = string_sprintf("job %s\n", message_id);
  history_buffer = string_sprintf("%sreporter %s\n", history_buffer, primary_hostname);
  history_buffer = string_sprintf("%sreceived %ld\n", history_buffer, time(NULL));
  history_buffer = string_sprintf("%sipaddr %s\n", history_buffer, sender_host_address);
  history_buffer = string_sprintf("%sfrom %s\n", history_buffer, header_from_sender);
  history_buffer = string_sprintf("%smfrom %s\n", history_buffer,
                     expand_string(US"$sender_address_domain"));

  if (spf_response != NULL)
    history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
    // history_buffer = string_sprintf("%sspf -1\n", history_buffer);

  history_buffer = string_sprintf("%s%s", history_buffer, dkim_history_buffer);
  history_buffer = string_sprintf("%spdomain %s\n", history_buffer, dmarc_used_domain);
  history_buffer = string_sprintf("%spolicy %d\n", history_buffer, dmarc_policy);

  rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1);
  if (rua != NULL)
  {
    for (tmp_ans = 0; rua[tmp_ans] != NULL; tmp_ans++)
    {
      history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
    }
  }
  else
    history_buffer = string_sprintf("%srua -\n", history_buffer);

  opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
  history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);

  opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
  history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);

  opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
  history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);

  opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
  history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);

  opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
  history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);

  history_buffer = string_sprintf("%salign_dkim %d\n", history_buffer, da);
  history_buffer = string_sprintf("%salign_spf %d\n", history_buffer, sa);
  history_buffer = string_sprintf("%saction %d\n", history_buffer, action);

  /* Write the contents to the history file */
  DEBUG(D_receive)
    debug_printf("DMARC logging history data for opendmarc reporting%s\n",
                 (host_checking || running_in_test_harness) ? " (not really)" : "");
  if (host_checking || running_in_test_harness)
  {
    DEBUG(D_receive)
      debug_printf("DMARC history data for debugging:\n%s", history_buffer);
  }
  else
  {
    written_len = write_to_fd_buf(history_file_fd,
                                  history_buffer,
                                  Ustrlen(history_buffer));
    if (written_len == 0)
    {
      log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
                             dmarc_history_file);
      return DMARC_HIST_WRITE_ERR;
    }
    (void)close(history_file_fd);
  }
  return DMARC_HIST_OK;
}

void dmarc_send_forensic_report(u_char **ruf)
{
  int   c;
  uschar *recipient, *save_sender;
  BOOL  send_status = FALSE;
  error_block *eblock = NULL;
  FILE *message_file = NULL;

  /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
  if (dmarc_enable_forensic == FALSE)
    return;

  if ((dmarc_policy == DMARC_POLICY_REJECT     && action == DMARC_RESULT_REJECT) ||
      (dmarc_policy == DMARC_POLICY_QUARANTINE && action == DMARC_RESULT_QUARANTINE) )
  {
    if (ruf != NULL)
    {
      eblock = add_to_eblock(eblock, US"Sender Domain", dmarc_used_domain);
      eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address);
      eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full));
      eblock = add_to_eblock(eblock, US"SPF Alignment",
                             (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?US"yes":US"no");
      eblock = add_to_eblock(eblock, US"DKIM Alignment",
                             (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?US"yes":US"no");
      eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text);
      /* Set a sane default envelope sender */
      dsn_from = dmarc_forensic_sender ? dmarc_forensic_sender :
                 dsn_from ? dsn_from :
                 string_sprintf("do-not-reply@%s",primary_hostname);
      for (c = 0; ruf[c] != NULL; c++)
      {
        recipient = string_copylc(ruf[c]);
        if (Ustrncmp(recipient, "mailto:",7))
        continue;
        /* Move to first character past the colon */
        recipient += 7;
        DEBUG(D_receive)
          debug_printf("DMARC forensic report to %s%s\n", recipient,
                       (host_checking || running_in_test_harness) ? " (not really)" : "");
        if (host_checking || running_in_test_harness)
          continue;
        save_sender = sender_address;
        sender_address = recipient;
        send_status = moan_to_sender(ERRMESS_DMARC_FORENSIC, eblock,
                                     header_list, message_file, FALSE);
        sender_address = save_sender;
        if (send_status == FALSE)
          log_write(0, LOG_MAIN|LOG_PANIC, "failure to send DMARC forensic report to %s",
                    recipient);
      }
    }
  }
}

uschar *dmarc_exim_expand_query(int what)
{
  if (dmarc_disable_verify || !dmarc_pctx)
    return dmarc_exim_expand_defaults(what);

  switch(what) {
    case DMARC_VERIFY_STATUS:
      return(dmarc_status);
    default:
      return US"";
  }
}

uschar *dmarc_exim_expand_defaults(int what)
{
  switch(what) {
    case DMARC_VERIFY_STATUS:
      return (dmarc_disable_verify) ?
              US"off" :
              US"none";
    default:
      return US"";
  }
}

uschar *dmarc_auth_results_header(header_line *from_header, uschar *hostname)
{
  uschar *hdr_tmp    = US"";

  /* Allow a server hostname to be passed to this function, but is
   * currently unused */
  if (hostname == NULL)
    hostname = primary_hostname;
  hdr_tmp = string_sprintf("%s %s;", DMARC_AR_HEADER, hostname);

#if 0
  /* I don't think this belongs here, but left it here commented out
   * because it was a lot of work to get working right. */
  if (spf_response != NULL) {
    uschar *dmarc_ar_spf = US"";
    int sr               = 0;
    sr = spf_response->result;
    dmarc_ar_spf = (sr == SPF_RESULT_NEUTRAL)  ? US"neutral" :
                   (sr == SPF_RESULT_PASS)     ? US"pass" :
                   (sr == SPF_RESULT_FAIL)     ? US"fail" :
                   (sr == SPF_RESULT_SOFTFAIL) ? US"softfail" :
                   US"none";
    hdr_tmp = string_sprintf("%s spf=%s (%s) smtp.mail=%s;",
                             hdr_tmp, dmarc_ar_spf_result,
                             spf_response->header_comment,
                             expand_string(US"$sender_address") );
  }
#endif
  hdr_tmp = string_sprintf("%s dmarc=%s",
                           hdr_tmp, dmarc_pass_fail);
  if (header_from_sender)
    hdr_tmp = string_sprintf("%s header.from=%s",
                             hdr_tmp, header_from_sender);
  return hdr_tmp;
}

#endif /* EXPERIMENTAL_SPF */
#endif /* EXPERIMENTAL_DMARC */

// vim:sw=2 expandtab