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fix: parse Link rel="alternate" in any parameter position #77

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Merged
toddr merged 1 commit into from
Apr 23, 2026
Merged

fix: parse Link rel="alternate" in any parameter position #77

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5 changes: 2 additions & 3 deletions lib/Net/ACME2.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -923,9 +923,8 @@ sub _parse_link_alternates {

my @alt_urls;
for my $link (@links) {
if ($link =~ m{<([^>]+)>\s*;\s*rel="alternate"}i) {
push @alt_urls, $1;
}
next unless $link =~ m{;\s*rel="alternate"}i;
push @alt_urls, $1 if $link =~ m{<([^>]+)>};
}

return @alt_urls;
Expand Down
68 changes: 62 additions & 6 deletions t/Net-ACME2-link-alternates.t
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Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,9 @@ use Test::More;
use Test::FailWarnings;

# _parse_link_alternates is a private function in Net::ACME2.
# We test it directly to verify RFC 8288 compliance (case-insensitive
# relation types).
# We test it directly to verify RFC 8288 compliance:
# - relation types are case-insensitive (section 2.1.1)
# - link parameters may appear in any order (section 3)

use Net::ACME2 ();

Expand All @@ -33,7 +34,7 @@ use Net::ACME2 ();
is( scalar @urls, 0, 'no Link header returns empty list' );
}

# --- Single alternate link (lowercase) ---
# --- Single alternate link ---
{
my $resp = MockResponse->new(
link => '<https://ca.example/cert/alt1>;rel="alternate"',
Expand All @@ -42,7 +43,7 @@ use Net::ACME2 ();
is_deeply(
\@urls,
['https://ca.example/cert/alt1'],
'single lowercase alternate link',
'single alternate link',
);
}

Expand Down Expand Up @@ -87,7 +88,7 @@ use Net::ACME2 ();
);
}

# --- RFC 8288: relation types are case-insensitive ---
# --- RFC 8288 section 2.1.1: relation types are case-insensitive ---
{
my $resp = MockResponse->new(
link => '<https://ca.example/cert/alt1>;rel="Alternate"',
Expand All @@ -112,7 +113,7 @@ use Net::ACME2 ();
);
}

# --- Whitespace variations in Link header ---
# --- Whitespace variations ---
{
my $resp = MockResponse->new(
link => '<https://ca.example/cert/alt1> ; rel="alternate"',
Expand All @@ -125,4 +126,59 @@ use Net::ACME2 ();
);
}

# --- RFC 8288 section 3: parameters may appear in any order ---
# The rel parameter does not need to be the first parameter after the URI.
{
my $resp = MockResponse->new(
link => '<https://ca.example/cert/alt1>; title="cross-signed"; rel="alternate"',
);
my @urls = Net::ACME2::_parse_link_alternates($resp);
is_deeply(
\@urls,
['https://ca.example/cert/alt1'],
'rel after other params (title before rel)',
);
}

{
my $resp = MockResponse->new(
link => '<https://ca.example/cert/alt1>; type="application/pem-certificate-chain"; rel="alternate"',
);
my @urls = Net::ACME2::_parse_link_alternates($resp);
is_deeply(
\@urls,
['https://ca.example/cert/alt1'],
'rel after type param',
);
}

{
my $resp = MockResponse->new(
link => '<https://ca.example/cert/alt1>; rel="alternate"; title="ISRG Root X2"',
);
my @urls = Net::ACME2::_parse_link_alternates($resp);
is_deeply(
\@urls,
['https://ca.example/cert/alt1'],
'rel before other params (rel then title)',
);
}

# --- rel in any position with mixed links ---
{
my $resp = MockResponse->new(
link => [
'<https://ca.example/directory>; rel="index"',
'<https://ca.example/cert/alt1>; title="cross-signed"; rel="alternate"',
'<https://ca.example/cert/alt2>; rel="alternate"; title="ISRG Root X2"',
],
);
my @urls = Net::ACME2::_parse_link_alternates($resp);
is_deeply(
\@urls,
['https://ca.example/cert/alt1', 'https://ca.example/cert/alt2'],
'mixed links with rel in various positions',
);
}

done_testing();
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