diff options
| author | Omar Polo <op@cvs.openbsd.org> | 2023-11-08 08:46:36 +0000 |
|---|---|---|
| committer | Omar Polo <op@cvs.openbsd.org> | 2023-11-08 08:46:36 +0000 |
| commit | c41f0fbc4ce4cbb382fca20110b7e2b0bf3c8103 (patch) | |
| tree | 3bfae149932ce2208ff47bd536b07dbbd6701abc /usr.sbin/smtpd | |
| parent | ff3df5dad575469ddca8e763ca236e6b8bc6b75a (diff) | |
RFC 7505 ("Null MX") handling
mail delivery will not be attempted if a domain advertises a single MX
record with preference 0 and a zero-length label.
based on an initial diff from Philipp (philipp+openbsd [at] bureaucracy
[dot] de), thanks!
ok jung@
Diffstat (limited to 'usr.sbin/smtpd')
| -rw-r--r-- | usr.sbin/smtpd/dns.c | 20 | ||||
| -rw-r--r-- | usr.sbin/smtpd/mta.c | 6 | ||||
| -rw-r--r-- | usr.sbin/smtpd/smtpd.h | 4 |
3 files changed, 26 insertions, 4 deletions
diff --git a/usr.sbin/smtpd/dns.c b/usr.sbin/smtpd/dns.c index 4cf5d23d1d1..dc7987aa29c 100644 --- a/usr.sbin/smtpd/dns.c +++ b/usr.sbin/smtpd/dns.c @@ -1,4 +1,4 @@ -/* $OpenBSD: dns.c,v 1.90 2021/06/14 17:58:15 eric Exp $ */ +/* $OpenBSD: dns.c,v 1.91 2023/11/08 08:46:34 op Exp $ */ /* * Copyright (c) 2008 Gilles Chehade <gilles@poolp.org> @@ -232,10 +232,10 @@ dns_dispatch_mx(struct asr_result *ar, void *arg) struct dns_rr rr; char buf[512]; size_t found; + int nullmx = 0; if (ar->ar_h_errno && ar->ar_h_errno != NO_DATA && ar->ar_h_errno != NOTIMP) { - m_create(s->p, IMSG_MTA_DNS_HOST_END, 0, 0, -1); m_add_id(s->p, s->reqid); if (ar->ar_rcode == NXDOMAIN) @@ -259,13 +259,29 @@ dns_dispatch_mx(struct asr_result *ar, void *arg) unpack_rr(&pack, &rr); if (rr.rr_type != T_MX) continue; + print_dname(rr.rr.mx.exchange, buf, sizeof(buf)); buf[strlen(buf) - 1] = '\0'; + + if (rr.rr.mx.preference == 0 && !strcmp(buf, "")) { + nullmx = 1; + continue; + } + dns_lookup_host(s, buf, rr.rr.mx.preference); found++; } free(ar->ar_data); + if (nullmx && found == 0) { + m_create(s->p, IMSG_MTA_DNS_HOST_END, 0, 0, -1); + m_add_id(s->p, s->reqid); + m_add_int(s->p, DNS_NULLMX); + m_close(s->p); + free(s); + return; + } + /* fallback to host if no MX is found. */ if (found == 0) dns_lookup_host(s, s->name, 0); diff --git a/usr.sbin/smtpd/mta.c b/usr.sbin/smtpd/mta.c index c0d0fc02931..f0bb42c53ff 100644 --- a/usr.sbin/smtpd/mta.c +++ b/usr.sbin/smtpd/mta.c @@ -1,4 +1,4 @@ -/* $OpenBSD: mta.c,v 1.245 2023/05/31 16:51:46 op Exp $ */ +/* $OpenBSD: mta.c,v 1.246 2023/11/08 08:46:35 op Exp $ */ /* * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org> @@ -1088,6 +1088,10 @@ mta_on_mx(void *tag, void *arg, void *data) else relay->failstr = "No MX found for domain"; break; + case DNS_NULLMX: + relay->fail = IMSG_MTA_DELIVERY_PERMFAIL; + relay->failstr = "Domain does not accept mail"; + break; default: fatalx("bad DNS lookup error code"); break; diff --git a/usr.sbin/smtpd/smtpd.h b/usr.sbin/smtpd/smtpd.h index 6781286928d..25090c3acf9 100644 --- a/usr.sbin/smtpd/smtpd.h +++ b/usr.sbin/smtpd/smtpd.h @@ -1,4 +1,4 @@ -/* $OpenBSD: smtpd.h,v 1.678 2023/09/29 18:30:14 op Exp $ */ +/* $OpenBSD: smtpd.h,v 1.679 2023/11/08 08:46:35 op Exp $ */ /* * Copyright (c) 2008 Gilles Chehade <gilles@poolp.org> @@ -1026,6 +1026,8 @@ enum dns_error { DNS_EINVAL, DNS_ENONAME, DNS_ENOTFOUND, + /* RFC 7505 */ + DNS_NULLMX, }; enum lka_resp_status { |