/**
* @return 成功した場合は NETDB_SUCCESS.
*/
static int
DnsResolver_lookupTxtData(DnsResolver *self, int rrtype, const char *domain, DnsTxtResponse **resp)
{
int query_stat = DnsResolver_query(self, domain, rrtype);
if (NETDB_SUCCESS != query_stat) {
return query_stat;
} // end if
size_t msg_count = ns_msg_count(self->msghanlde, ns_s_an);
DnsTxtResponse *respobj =
(DnsTxtResponse *) malloc(sizeof(DnsTxtResponse) + msg_count * sizeof(char *));
if (NULL == respobj) {
return DnsResolver_setError(self, NETDB_INTERNAL);
} // end if
memset(respobj, 0, sizeof(DnsTxtResponse) + msg_count * sizeof(char *));
respobj->num = 0;
for (size_t n = 0; n < msg_count; ++n) {
ns_rr rr;
int parse_stat = ns_parserr(&self->msghanlde, ns_s_an, n, &rr);
if (0 != parse_stat) {
goto formerr;
} // end if
if (ns_t_txt != ns_rr_type(rr)) {
continue;
} // end if
respobj->data[respobj->num] = (char *) malloc(ns_rr_rdlen(rr)); // RDLEN を越えることはない.
if (NULL == respobj->data[respobj->num]) {
goto noresource;
} // end if
const unsigned char *rdata = ns_rr_rdata(rr);
const unsigned char *rdata_tail = ns_rr_rdata(rr) + ns_rr_rdlen(rr);
char *bufp = respobj->data[respobj->num];
while (rdata < rdata_tail) {
// 長さフィールドが RDLEN の中に収まっているか確認する
if (rdata_tail < rdata + (*rdata) + 1) {
free(respobj->data[respobj->num]);
goto formerr;
} // end if
memcpy(bufp, rdata + 1, *rdata);
bufp += (size_t) *rdata;
rdata += (size_t) *rdata + 1;
} // end while
*bufp = '\0'; // 扱いやすいように NULL 終端させる
++(respobj->num);
} // end for
if (0 == respobj->num) {
goto formerr;
} // end if
*resp = respobj;
return NETDB_SUCCESS;
formerr:
DnsTxtResponse_free(respobj);
return DnsResolver_setError(self, NO_RECOVERY);
noresource:
DnsTxtResponse_free(respobj);
return DnsResolver_setError(self, NETDB_INTERNAL);
} // end function : DnsResolver_lookupTxtData
void
DnsSpfResponse_free(DnsSpfResponse *self)
{
DnsTxtResponse_free(self);
} // end function : DnsSpfResponse_free
/**
* @return DSTAT_OK for success, otherwise status code that indicates error.
* @error DSTAT_INFO_ADSP_NOT_EXIST ADSP record have not found
* @error DSTAT_PERMFAIL_MULTIPLE_ADSP_RECORD multiple ADSP records are found
* @error DSTAT_TMPERR_DNS_ERROR_RESPONSE DNS lookup error (received error response)
* @error DSTAT_SYSERR_DNS_LOOKUP_FAILURE DNS lookup error (failed to lookup itself)
* @error DSTAT_SYSERR_IMPLERROR obvious implementation error
* @error DSTAT_SYSERR_NORESOURCE memory allocation error
*/
static DkimAdsp *
DkimAdsp_query(const DkimPolicyBase *policy, DnsResolver *resolver, const char *domain,
DkimStatus *dstat)
{
assert(NULL != resolver);
assert(NULL != domain);
// lookup ADSP record
DnsTxtResponse *txt_rr = NULL;
dns_stat_t txtquery_stat = DnsResolver_lookupTxt(resolver, domain, &txt_rr);
switch (txtquery_stat) {
case DNS_STAT_NOERROR:;
// a TXT RR is found
/*
* [RFC5617] 4.3.
* If the result of this query is a NOERROR response (rcode=0 in
* [RFC1035]) with an answer that is a single record that is a valid
* ADSP record, use that record, and the algorithm terminates.
*/
if (0 == DnsTxtResponse_size(txt_rr)) {
// no TXT records are found
DnsTxtResponse_free(txt_rr);
SETDEREF(dstat, DSTAT_INFO_ADSP_NOT_EXIST);
break;
} else if (1 < DnsTxtResponse_size(txt_rr)) {
// multiple TXT records are found
DnsTxtResponse_free(txt_rr);
SETDEREF(dstat, DSTAT_PERMFAIL_MULTIPLE_ADSP_RECORD);
break;
} // end if
// only one TXT record is found, and now, try to parse as ADSP record
DkimStatus build_stat;
const char *txtrecord = DnsTxtResponse_data(txt_rr, 0);
DkimAdsp *self = DkimAdsp_build(policy, txtrecord, &build_stat);
if (NULL != self) {
// parsed as a valid ADSP record
DnsTxtResponse_free(txt_rr);
SETDEREF(dstat, DSTAT_OK);
return self;
} else if (DSTAT_ISCRITERR(build_stat)) {
// propagate system errors as-is
DkimLogSysError
(policy,
"System error has occurred while parsing ADSP record: domain=%s, err=%s, record=%s",
domain, DKIM_strerror(build_stat), NNSTR(txtrecord));
SETDEREF(dstat, build_stat);
} else if (DSTAT_ISPERMFAIL(build_stat)) {
/*
* treat syntax errors on ADSP record as DNS NODATA response
*
* [RFC5617] 4.1.
* Records not in compliance with that syntax
* or the syntax of individual tags described in Section 4.3 MUST be
* ignored (considered equivalent to a NODATA result) for purposes of
* ADSP, although they MAY cause the logging of warning messages via an
* appropriate system logging mechanism.
*/
DkimLogDebug(policy, "ADSP record candidate discarded: domain=%s, err=%s, record=%s",
domain, DKIM_strerror(build_stat), NNSTR(txtrecord));
SETDEREF(dstat, DSTAT_INFO_ADSP_NOT_EXIST);
} else {
DkimLogNotice(policy, "DkimAdsp_build failed: domain=%s, err=%s, record=%s",
domain, DKIM_strerror(build_stat), NNSTR(txtrecord));
SETDEREF(dstat, DSTAT_INFO_ADSP_NOT_EXIST);
} // end if
// a TXT RR is not a valid ADSP record
DnsTxtResponse_free(txt_rr);
break;
case DNS_STAT_NXDOMAIN:
case DNS_STAT_NODATA:
/*
* no TXT (and ADSP) records are found
*
* [RFC5617] 4.3.
* If the result of the query is NXDOMAIN or NOERROR with zero
* records, there is no ADSP record. If the result of the query
* contains more than one record, or a record that is not a valid
* ADSP record, the ADSP result is undefined.
*/
DkimLogDebug(policy, "No ADSP record is found on DNS: domain=%s", domain);
SETDEREF(dstat, DSTAT_INFO_ADSP_NOT_EXIST);
break;
case DNS_STAT_FORMERR:
case DNS_STAT_SERVFAIL:
case DNS_STAT_NOTIMPL:
case DNS_STAT_REFUSED:
case DNS_STAT_YXDOMAIN:
case DNS_STAT_YXRRSET:
case DNS_STAT_NXRRSET:
case DNS_STAT_NOTAUTH:
case DNS_STAT_NOTZONE:
case DNS_STAT_RESERVED11:
case DNS_STAT_RESERVED12:
case DNS_STAT_RESERVED13:
case DNS_STAT_RESERVED14:
case DNS_STAT_RESERVED15:
/*
* [RFC5617] 4.3.
* If a query results in a "SERVFAIL" error response (rcode=2 in
* [RFC1035]), the algorithm terminates without returning a result;
* possible actions include queuing the message or returning an SMTP
* error indicating a temporary failure.
*/
DkimLogInfo(policy, "DNS error on ADSP record look-up: domain=%s, type=txt, err=%s",
domain, DnsResolver_getErrorString(resolver));
SETDEREF(dstat, DSTAT_TMPERR_DNS_ERROR_RESPONSE);
break;
case DNS_STAT_SYSTEM:
case DNS_STAT_RESOLVER:
case DNS_STAT_RESOLVER_INTERNAL:
DkimLogSysError(policy, "error occurred during DNS lookup: domain=%s, type=txt, err=%s",
domain, DnsResolver_getErrorString(resolver));
SETDEREF(dstat, DSTAT_SYSERR_DNS_LOOKUP_FAILURE);
break;
case DNS_STAT_NOMEMORY:
DkimLogNoResource(policy);
SETDEREF(dstat, DSTAT_SYSERR_NORESOURCE);
break;
case DNS_STAT_BADREQUEST:
default:
DkimLogImplError(policy,
"DnsResolver_lookupTxt returns unexpected value: value=0x%x, domain=%s, type=txt",
txtquery_stat, domain);
SETDEREF(dstat, DSTAT_SYSERR_IMPLERROR);
break;
} // end switch
return NULL;
} // end function: DkimAdsp_query
