send-email: improve RFC2047 quote parsing

The RFC2047 unquoting, used to parse email addresses in From and Cc
headers, is broken in several ways:

* It erroneously substitutes ' ' for '_' in *the whole* header, even
  outside the quoted field. [Noticed by Christoph.]

* It is too liberal in its matching, and happily matches the start
  of one quoted chunk against the end of another, or even just
  something that looks like such an end. [Noticed by Junio.]

* It fundamentally cannot cope with encodings that are not a
  superset of ASCII, nor several (incompatible) encodings in the
  same header.

This patch fixes the first two by doing a more careful decoding of
the outer quoting (e.g. "=AB" to represent an octet whose value is
0xAB).  Fixing the fundamental issues is left for a future, more
intrusive, patch.

Noticed-by: Christoph Miebach <christoph.miebach@web.de>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/git-send-email.perl b/git-send-email.perl
index ef30c55..6647137 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -862,11 +862,13 @@ $time = time - scalar $#files;
 sub unquote_rfc2047 {
 	local ($_) = @_;
 	my $encoding;
-	if (s/=\?([^?]+)\?q\?(.*)\?=/$2/g) {
+	s{=\?([^?]+)\?q\?(.*?)\?=}{
 		$encoding = $1;
-		s/_/ /g;
-		s/=([0-9A-F]{2})/chr(hex($1))/eg;
-	}
+		my $e = $2;
+		$e =~ s/_/ /g;
+		$e =~ s/=([0-9A-F]{2})/chr(hex($1))/eg;
+		$e;
+	}eg;
 	return wantarray ? ($_, $encoding) : $_;
 }