[PATCH] checkpatch: make email address check case insensitive

[Mimi Zohar]

Instead of checkpatch requiring the patch author to exactly match the
signed-off-by tag, commit 48ca2d8ac8a1 ("checkpatch: add new warnings
to author signoff checks.") safely relaxed this requirement.

Although the local-part of an email address (local-part@domain), may
be case sensitive, exploiting the case sensitivity of mailbox
local-parts impedes interoperability and is discouraged.  Mailbox
domains follow normal DNS rules and are hence not case sensitive.
(Refer to https://datatracker.ietf.org/doc/html/rfc5321#section-2.4.)

Further relax the patch author and signed-off-by tag comparison by
making the email address check case insensitive.

Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
---
 scripts/checkpatch.pl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 461d4221e4a4..1efa2997df62 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2909,10 +2909,10 @@ sub process {
 					my ($email_name, $email_comment, $email_address, $comment1) = parse_email($ctx);
 					my ($author_name, $author_comment, $author_address, $comment2) = parse_email($author);
 
-					if ($email_address eq $author_address && $email_name eq $author_name) {
+					if (lc $email_address eq lc $author_address && $email_name eq $author_name) {
 						$author_sob = $ctx;
 						$authorsignoff = 2;
-					} elsif ($email_address eq $author_address) {
+					} elsif (lc $email_address eq lc $author_address) {
 						$author_sob = $ctx;
 						$authorsignoff = 3;
 					} elsif ($email_name eq $author_name) {
-- 
2.27.0