fix: standardize X-Mailer, version string, and forensic relay tracing (#429)

* fix: use X-Mailer instead of User-Agent in milter failure reports

opendmarc-reports already labels aggregate reports with
X-Mailer: opendmarc-reports v<version>. The milter's own AFRF
failure-report path used User-Agent instead, so the two report types
disagreed on which header identifies the generating software.
Standardize both on X-Mailer.

* fix: align opendmarc-reports version string and mark forensic relay hop

opendmarc-reports' $version used the plain release version with no
git-describe logic, while the milter's DMARCF_VERSION already includes
a dirty-build hash suffix; identical dev builds reported different
version strings depending on which program authored a report.
configure.ac now AC_SUBST's DMARCF_VERSION for use in opendmarc-reports.in.

Also: --forensic mode relays the milter-composed message via Net::SMTP
without ever picking up a Received: header, unlike the direct
sendmail -t path which gets one for free from the local MTA. Prepend a
single Received: line identifying the relay hop, added before
archiving so --archive-dir captures what was actually sent.

Author: thegushi

CHANGES-202605.md

@@ -90,6 +90,9 @@ Significant gaps between the generated aggregate report XML and RFC 7489 require
 - **Distinct `ReportCommand` exit code for fully-suppressed reports**: When every recipient of a forensic report is suppressed by `NoReportsList`, StaleMARC, or the suppressions table, `opendmarc-reports --forensic` now exits `2` instead of `0`, and the milter logs this at `LOG_INFO` rather than treating it as a `ReportCommand` failure (previously indistinguishable from a normal send in the logs). (#424)
 - **`--archive-dir`**: New option saves a copy of every outbound report -- the full message as handed to SMTP, not just the gzipped XML or AFRF attachment -- to a directory for later review (e.g. RFC-compliance checking). Applies to both aggregate and forensic modes; suppressed and `--test`-mode reports are not archived. (#424)
 - **Bare `NoReportsList` domain entries now also suppress `--forensic` reports**: Previously a bare sending-domain entry only suppressed aggregate reports (via `--skipdomains`); the manpage explicitly noted "no effect on failure report (ruf=) suppression in the milter itself." `opendmarc-reports --forensic` now reads the `Reported-Domain` field from the AFRF message and checks it against the same `--skipdomains`/`NoReportsList`, StaleMARC, and suppressions-DB logic the aggregate path uses, discarding the report (exit code 2) if the domain is suppressed. Still has no effect when `ReportCommand` pipes directly to `sendmail` rather than through `opendmarc-reports`, since only the latter performs the check. (#425)
+- **Milter-generated failure reports now use `X-Mailer` instead of `User-Agent` for version identification**: `opendmarc-reports` already labelled aggregate reports with `X-Mailer: opendmarc-reports v<version>`, the long-established email convention for identifying the software that generated a message. The milter's own AFRF failure-report path used `User-Agent: %s/%s` instead, so the two report types disagreed on which header to use. Both now use `X-Mailer`.
+- **`opendmarc-reports`' version string now includes the git hash on development builds**: The milter's `DMARCF_VERSION` already ran `git describe --tags --dirty` at configure time so dev builds show a hash suffix (e.g. `1.4.2-3-gabc1234-dirty`); `opendmarc-reports` used the plain release version with no such logic, so identical dev builds reported different version strings depending on which program authored the report. `configure.ac` now `AC_SUBST`s `DMARCF_VERSION`, and `opendmarc-reports.in` uses it in place of `@VERSION@`.
+- **`opendmarc-reports --forensic` now leaves a `Received:` trace when relaying**: A report relayed by the milter's `ReportCommand` directly to `sendmail -t` picks up a normal `Received:` header from the local MTA, but `--forensic` mode talks to the configured SMTP server directly via `Net::SMTP` and otherwise passes the milter-composed message through completely untouched, leaving no indication the message passed through `opendmarc-reports` at all. A single `Received: by <host> (opendmarc-reports v<version>) via forensic relay; <date>` line is now prepended before sending (and before the message is archived via `--archive-dir`, so the archived copy matches what was actually sent), applied identically regardless of `--verp`.
 
 ---
 

configure.ac

@@ -82,6 +82,7 @@ fi
 AC_MSG_RESULT([$DMARCF_VERSION])
 AC_DEFINE_UNQUOTED([DMARCF_VERSION], ["$DMARCF_VERSION"],
                    [Version string, including git hash on development builds])
+AC_SUBST([DMARCF_VERSION])
 
 #
 # Hexadecimal version, for use in generating dmarc.h

opendmarc/opendmarc.c

@@ -3635,7 +3635,7 @@ mlfi_eom(SMFICTX *ctx)
 			                   "Version: 1\n");
 
 			dmarcf_dstring_printf(dfc->mctx_afrf,
-			                      "User-Agent: %s/%s\n",
+			                      "X-Mailer: %s/%s\n",
 			                      DMARCF_PRODUCTNS, DMARCF_VERSION);
 
 			dmarcf_dstring_cat(dfc->mctx_afrf,

reports/opendmarc-reports.in

@@ -30,7 +30,7 @@ require LWP::UserAgent;
 
 # general
 my $progname      = basename($0);
-my $version       = "@VERSION@";
+my $version       = "@DMARCF_VERSION@";
 my $verbose       = 0;
 my $helponly      = 0;
 my $showversion   = 0;
@@ -753,6 +753,13 @@ if ($forensic)
 	$smtp = smtp_connect();
 	exit(1) unless defined($smtp);
 
+	# Mark the relay hop so a recipient (or an admin troubleshooting
+	# delivery) can tell this report passed through opendmarc-reports
+	# rather than going straight out via the milter's ReportCommand
+	# (e.g. "sendmail -t"), which leaves no such trace of its own.
+	my $received_datestr = strftime("%a, %e %b %Y %H:%M:%S %z (%Z)", localtime);
+	$message = "Received: by " . hostfqdn() . " (opendmarc-reports v$version) via forensic relay; $received_datestr\n" . $message;
+
 	my $archive_label = $rcpts[0];
 	$archive_label .= "+" . (scalar(@rcpts) - 1) if @rcpts > 1;
 	archive_report($archive_label, $message);