From 434f494abcc3558c73efc0e57a4338adeb402253 Mon Sep 17 00:00:00 2001
From: John Jetmore <jj33@pobox.com>
Date: Sat, 25 Apr 2020 10:42:36 -0400
Subject: [PATCH] Simplify date string creation

Fix strange issue where GMT offset could oscillate on days of DST transition.  Time::Local is no longer used and POSIX is now required.

Fixes #17
---
 Changes      |  3 +++
 doc/base.pod |  2 +-
 swaks        | 27 +++++++++++----------------
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/Changes b/Changes
index cac2ccbb..3fc66235 100644
--- a/Changes
+++ b/Changes
@@ -906,3 +906,6 @@
            scrolling, remove stray quotes, remove the news section from index
            add announcement to versions, link to both plaintext and
            rendered docs, etc
+* 20200425 Fix strange issue where GMT offset could oscillate on days of DST
+           transition.  Time::Local is no longer used and POSIX is now
+           required (#17, deb bug 955798)
diff --git a/doc/base.pod b/doc/base.pod
index 5d2d7eae..83bc35c0 100644
--- a/doc/base.pod
+++ b/doc/base.pod
@@ -765,7 +765,7 @@ Replaced with the envelope-recipient(s).
 
 =item %DATE%
 
-Replaced with the current time in a format suitable for inclusion in the Date: header.  Note this attempts to use the standard module L<Time::Local> for timezone calculations.  If this module is unavailable the date string will be in GMT.
+Replaced with the current time in a format suitable for inclusion in the Date: header.  Note this attempts to use the standard module L<POSIX> for timezone calculations.  If this module is unavailable the date string will be in GMT.
 
 =item %MESSAGEID%
 
diff --git a/swaks b/swaks
index f163f4ca..052379ae 100755
--- a/swaks
+++ b/swaks
@@ -1641,7 +1641,7 @@ sub load_dependencies {
 		pipe            => { name => "Pipe Transport",           req => ['IPC::Open2']        },
 		socket          => { name => "Socket Transport",         req => ['IO::Socket']        },
 		ipv6            => { name => "IPv6",                     req => ['IO::Socket::INET6'] },
-		date_manip      => { name => "Date Manipulation",        req => ['Time::Local']       },
+		date_manip      => { name => "Date Manipulation",        req => ['POSIX']             },
 		hostname        => { name => "Local Hostname Detection", req => ['Sys::Hostname']     },
 		hires_timing    => { name => "High Resolution Timing",   req => ['Time::HiRes']       },
 	);
@@ -3743,25 +3743,20 @@ sub get_date_string {
 	return($G::date_string) if (length($G::date_string) > 0);
 
 	my $et = time();
-	my @l  = localtime($et);
-	my $o  = 0;
 
 	if (!avail("date_manip")) {
 		ptrans(12, avail_str("date_manip").".  Date strings will be in GMT");
-		@l = gmtime($et);
+		my @l = gmtime($et);
+		$G::date_string = sprintf("%s, %02d %s %d %02d:%02d:%02d %+05d",
+		                          (qw(Sun Mon Tue Wed Thu Fri Sat))[$l[6]],
+		                          $l[3],
+		                          (qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec))[$l[4]],
+		                          $l[5]+1900, $l[2], $l[1], $l[0],
+		                          0);
 	} else {
-		my @g = gmtime($et);
-		$o = (timelocal(@l) - timelocal(@g)) / 60;
-		# Adjust to hours and minutes and not hours and hour-hundreths
-		# See debian bug 646084
-		$o = int($o / 60)*100 + ($o%60)*($o > 0 ? 1 : -1);
-	}
-	$G::date_string = sprintf("%s, %02d %s %d %02d:%02d:%02d %+05d",
-	                          (qw(Sun Mon Tue Wed Thu Fri Sat))[$l[6]],
-	                          $l[3],
-	                          (qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec))[$l[4]],
-	                          $l[5]+1900, $l[2], $l[1], $l[0],
-	                          $o);
+		$G::date_string = POSIX::strftime("%a, %d %b %Y %H:%M:%S %z", localtime($et));
+	}
+	return($G::date_string);
 }
 
 # partially Cribbed from "Programming Perl" and MIME::Base64 v2.12