From f9f5db739e69cad3f1d19351f5c91e7a8831d069 Mon Sep 17 00:00:00 2001
From: ZachDreamZ <xxtheshadowcraft@gmail.com>
Date: Sat, 4 Jul 2026 00:30:03 +0800
Subject: [PATCH] fix: parse relative URLs with multiple leading slashes for
 special schemes

When a relative URL starts with more than two slashes (e.g. ///test)
and the base has a special scheme (http, https, ws, wss, ftp), the
parser should consume all leading slashes before parsing the authority,
matching the URL spec's special authority slashes state.

Previously, split_prefix("//") only consumed exactly two slashes,
leaving the remaining slash to be parsed as part of the authority,
which caused an empty host error for inputs like ///test with base
http://example.org/.

This fix adds a check for special schemes before the split_prefix
call, routing directly to after_double_slash which handles the
remaining input correctly.

Fixes URL parsing for:
  new URL('///test', 'http://example.org/') -> http://test/
  new URL('///example.org/path', 'http://example.org/') -> http://example.org/path

Removed 7 entries from expected_failures.txt that now pass correctly.
---
 url/src/parser.rs               | 3 +++
 url/tests/expected_failures.txt | 7 -------
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/url/src/parser.rs b/url/src/parser.rs
index dbdf9b906..8f2499a23 100644
--- a/url/src/parser.rs
+++ b/url/src/parser.rs
@@ -774,6 +774,9 @@ impl Parser<'_> {
                     debug_assert!(base_url.byte_at(scheme_end) == b':');
                     self.serialization
                         .push_str(base_url.slice(..scheme_end + 1));
+                    if scheme_type.is_special() {
+                        return self.after_double_slash(remaining, scheme_type, scheme_end);
+                    }
                     if let Some(after_prefix) = input.split_prefix("//") {
                         return self.after_double_slash(after_prefix, scheme_type, scheme_end);
                     }
diff --git a/url/tests/expected_failures.txt b/url/tests/expected_failures.txt
index 8d4407c45..860fcd516 100644
--- a/url/tests/expected_failures.txt
+++ b/url/tests/expected_failures.txt
@@ -53,13 +53,6 @@
 <non-special:opaque\t\t  \r #hi>
 <foo://host/ !\"$%&\'()*+,-./:;<=>@[\\]^_`{|}~>
 <wss://host/ !\"$%&\'()*+,-./:;<=>@[\\]^_`{|}~>
-<///test> against <http://example.org/>
-<///\\//\\//test> against <http://example.org/>
-<///example.org/path> against <http://example.org/>
-<///example.org/../path> against <http://example.org/>
-<///example.org/../../> against <http://example.org/>
-<///example.org/../path/../../> against <http://example.org/>
-<///example.org/../path/../../path> against <http://example.org/>
 </\\//\\/a/../> against <file:///>
 <a:/> set pathname to <\u{0}\u{1}\t\n\r\u{1f} !\"#$%&\'()*+,-./09:;<=>?@AZ[\\]^_`az{|}~\u{7f}\u{80}\u{81}\u{c9}\u{e9}>
 <data:space                                                                                                                                  #fragment> set hash to <>