From fbb8bcd2c8f470f1af56186aa23c49f2c2b6399f Mon Sep 17 00:00:00 2001
From: Arpad Ryszka <arpio@squareroundforest.org>
Date: Wed, 24 Jun 2026 03:28:42 +0200
Subject: [PATCH] fix url syntax

---
 doc/example/url.treerack |  14 ++---
 url_test.go              | 109 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 116 insertions(+), 7 deletions(-)

diff --git a/doc/example/url.treerack b/doc/example/url.treerack
index 1c0fb44..9ae0aa3 100644
--- a/doc/example/url.treerack
+++ b/doc/example/url.treerack
@@ -15,7 +15,7 @@ percent-encoded:alias:failpass = "%" hex{2};
 path-char:alias:failpass       = unreserved | percent-encoded | subdelimiter | ":" | "@";
 
 // scheme:
-scheme = alpha (alpha | digit | [+-.])*;
+scheme = alpha (alpha | digit | [+\-.])*;
 
 // userinfo:
 userinfo = (unreserved | percent-encoded | subdelimiter | ":")*;
@@ -30,12 +30,12 @@ ls32:alias:failpass    = h16 ":" h16 | ipv4;
 ipv6:failpass          = (h16 ":"){6} ls32
                        | "::" (h16 ":"){5} ls32
                        | h16? "::" (h16 ":"){4} ls32
-                       | ((h16 ":")? h16)? "::" (h16 ":"){3} ls32
-                       | ((h16 ":"){,2} h16)? "::" (h16 ":"){2} ls32
-                       | ((h16 ":"){,3} h16)? "::" h16 ":" ls32
-                       | ((h16 ":"){,4} h16)? "::" ls32
-                       | ((h16 ":"){,5} h16)? "::" h16
-                       | ((h16 ":"){,6} h16)? "::";
+                       | (h16 (":" h16)?)? "::" (h16 ":"){3} ls32
+                       | (h16 (":" h16){,2})? "::" (h16 ":"){2} ls32
+                       | (h16 (":" h16){,3})? "::" h16 ":" ls32
+                       | (h16 (":" h16){,4})? "::" ls32
+                       | (h16 (":" h16){,5})? "::" h16
+                       | (h16 (":" h16){,6})? "::";
 zone-id:alias:failpass = (unreserved | percent-encoded)+;
 ipv6-zone:failpass     = ipv6 "%25" zone-id; // RFC6874
 
diff --git a/url_test.go b/url_test.go
index 8aea823..a3f02ce 100644
--- a/url_test.go
+++ b/url_test.go
@@ -266,6 +266,79 @@ func TestURL(t *testing.T) {
 		}},
 	}, {
 
+		title: "scheme and host ipv4 as domain name because of numeric range",
+		input: "http://256.0.0.1",
+		checks: []urlCheck{{
+			stdQuery:      func(u *url.URL) string { return u.Scheme },
+			treerackQuery: queryTreerack("absolute-url", "scheme"),
+			expect:        "http",
+		}, {
+			stdQuery:      func(u *url.URL) string { return u.Host },
+			treerackQuery: queryTreerack("absolute-url", "hostname", "domain-name"),
+			expect:        "256.0.0.1",
+		}},
+	}, {
+
+		title: "scheme and host ipv4 as domain name because of leading zero",
+		input: "http://128.0.0.01",
+		checks: []urlCheck{{
+			stdQuery:      func(u *url.URL) string { return u.Scheme },
+			treerackQuery: queryTreerack("absolute-url", "scheme"),
+			expect:        "http",
+		}, {
+			stdQuery:      func(u *url.URL) string { return u.Host },
+			treerackQuery: queryTreerack("absolute-url", "hostname", "domain-name"),
+			expect:        "128.0.0.01",
+		}},
+	}, {
+
+		title: "scheme and host ipv4",
+		input: "http://128.0.0.1",
+		checks: []urlCheck{{
+			stdQuery:      func(u *url.URL) string { return u.Scheme },
+			treerackQuery: queryTreerack("absolute-url", "scheme"),
+			expect:        "http",
+		}, {
+			stdQuery:      func(u *url.URL) string { return u.Host },
+			treerackQuery: queryTreerack("absolute-url", "hostname", "ipv4"),
+			expect:        "128.0.0.1",
+		}},
+	}, {
+
+		title: "scheme and host ipv6",
+		input: "http://[fe80::1]",
+		checks: []urlCheck{{
+			stdQuery:      func(u *url.URL) string { return u.Scheme },
+			treerackQuery: queryTreerack("absolute-url", "scheme"),
+			expect:        "http",
+		}, {
+			stdQuery:      func(u *url.URL) string { return u.Host },
+			treerackQuery: fakeTRCheck("[fe80::1]"),
+			expect:        "[fe80::1]",
+		}, {
+			stdQuery:      fakeSTDCheck("fe80::1"),
+			treerackQuery: queryTreerack("absolute-url", "hostname", "ipv6"),
+			expect:        "fe80::1",
+		}},
+	}, {
+
+		title: "scheme and host ipv6 with zone",
+		input: "http://[fe80::1%25eth0]",
+		checks: []urlCheck{{
+			stdQuery:      func(u *url.URL) string { return u.Scheme },
+			treerackQuery: queryTreerack("absolute-url", "scheme"),
+			expect:        "http",
+		}, {
+			stdQuery:      func(u *url.URL) string { return u.Host },
+			treerackQuery: fakeTRCheck("[fe80::1%eth0]"),
+			expect:        "[fe80::1%eth0]",
+		}, {
+			stdQuery:      fakeSTDCheck("fe80::1%25eth0"),
+			treerackQuery: queryTreerack("absolute-url", "hostname", "ipv6-zone"),
+			expect:        "fe80::1%25eth0",
+		}},
+	}, {
+
 		title: "scheme and host with port",
 		input: "http://foo.bar:8080",
 		checks: []urlCheck{{
@@ -1480,3 +1553,39 @@ func TestURL(t *testing.T) {
 		})
 	}
 }
+
+func TestURLErrors(t *testing.T) {
+	for _, test := range []struct{ title, input string }{{
+
+		title: "scheme cannot start on a number",
+		input: "123http://foo.bar/foo/bar",
+	}, {
+
+		title: "scheme characters",
+		input: "http,unix://foo.bar/foo/bar",
+	}, {
+
+		title: "ipv4 in brackets",
+		input: "http://[128.0.0.1]",
+	}, {
+
+		title: "ipv6 without closing bracket",
+		input: "http://[fe80::1%25eth0",
+	}, {
+
+		title: "invalid port",
+		input: "http://foo.bar:99x99",
+	}, {
+
+		title: "invalid path",
+		input: "http://foo.bar/foo%xbar",
+	}} {
+		t.Run(test.title, func(t *testing.T) {
+			p := urlParser()
+			if a, err := p(test.input); err == nil {
+				printURLTree(t, a)
+				t.Fatal("failed to fail", test.input)
+			}
+		})
+	}
+}