ResolvedDomain should handle domain with root label

Author: nyamsprod

src/ResolvedDomain.php

@@ -199,10 +199,10 @@ public function withSuffix(DomainNameProvider|Host|Stringable|string|int|null $s
             $suffix = Suffix::fromUnknown($suffix);
         }
 
-        $newDomain = $this->domain->withoutRootLabel()->slice(count($this->suffix))->append($suffix);
+        $domain = $this->domain->withoutRootLabel()->slice(count($this->suffix))->append($suffix);
 
         return new self(
-            $this->domain->isAbsolute() ? $newDomain->withRootLabel() : $newDomain,
+            $this->domain->isAbsolute() ? $domain->withRootLabel() : $domain,
             $suffix->normalize($this->domain)
         );
     }
@@ -217,15 +217,20 @@ public function withSubDomain(DomainNameProvider|Host|Stringable|string|int|null
         }
 
         $subDomain = RegisteredName::fromIDNA2008($subDomain);
-        if ('' === $subDomain->withoutRootLabel()->value()) {
-            throw SyntaxError::dueToMalformedValue($subDomain->toString());
+        if ($subDomain->isAbsolute()) {
+            $subDomain = $subDomain->withoutRootLabel();
+            if (null === $subDomain->value()) {
+                throw SyntaxError::dueToMalformedValue($subDomain->withRootLabel()->toString());
+            }
         }
 
         if ($this->subDomain->value() === $subDomain->value()) {
             return $this;
         }
 
-        return new self($this->registrableDomain->prepend($subDomain), $this->suffix);
+        $domain = $this->registrableDomain->prepend($subDomain);
+
+        return new self($this->domain->isAbsolute() ? $domain->withRootLabel() : $domain, $this->suffix);
     }
 
     /**
@@ -238,6 +243,13 @@ public function withSecondLevelDomain(DomainNameProvider|Host|Stringable|string|
         }
 
         $label = RegisteredName::fromIDNA2008($label);
+        if ($label->isAbsolute()) {
+            if (2 !== count($label)) {
+                throw UnableToResolveDomain::dueToInvalidSecondLevelDomain($label);
+            }
+            $label = $label->withoutRootLabel();
+        }
+
         if (1 !== count($label)) {
             throw UnableToResolveDomain::dueToInvalidSecondLevelDomain($label);
         }

src/ResolvedDomainTest.php

@@ -533,6 +533,13 @@ public static function withSldWorksProvider(): iterable
                 'expectedSld' => 'www',
                 'expectedHost' => 'www.com',
             ],
+            [
+                'host' => 'example.com',
+                'publicSuffix' => 'com',
+                'sld' => 'www.',
+                'expectedSld' => 'www',
+                'expectedHost' => 'www.com',
+            ],
             [
                 'host' => 'www.example.com',
                 'publicSuffix' => 'com',
@@ -547,6 +554,13 @@ public static function withSldWorksProvider(): iterable
                 'expectedSld' => 'hamburger',
                 'expectedHost' => 'www.hamburger.co.uk',
             ],
+            [
+                'host' => 'www.bbc.co.uk',
+                'publicSuffix' => 'co.uk',
+                'sld' => 'hamburger.',
+                'expectedSld' => 'hamburger',
+                'expectedHost' => 'www.hamburger.co.uk',
+            ],
         ];
     }
 
@@ -557,6 +571,20 @@ public function testItCanNotAppendAnEmptySLD(): void
         ResolvedDomain::fromICANN('private.ulb.ac.be', 2)->withSecondLevelDomain(null);
     }
 
+    public function testItCanNotAppendAnEmptyRootLabelSLD(): void
+    {
+        $this->expectException(SyntaxError::class);
+
+        ResolvedDomain::fromICANN('private.ulb.ac.be', 2)->withSecondLevelDomain('.');
+    }
+
+    public function testItCanNotAppendAnInvalidRootLabelSLD(): void
+    {
+        $this->expectException(UnableToResolveDomain::class);
+
+        ResolvedDomain::fromICANN('private.ulb.ac.be', 2)->withSecondLevelDomain('toto.foo.');
+    }
+
     public function testItCanNotAppendASLDToAResolvedDomainWithoutSuffix(): void
     {
         $this->expectException(UnableToResolveDomain::class);
@@ -571,6 +599,13 @@ public function testItCanNotAppendAnInvalidSLDToAResolvedDomain(): void
         ResolvedDomain::fromIANA('private.ulb.ac.be')->withSecondLevelDomain('foo.bar');
     }
 
+    public function testItCanNotAppendAnInvalidSubDomainToAResolvedDomain(): void
+    {
+        $this->expectException(SyntaxError::class);
+
+        ResolvedDomain::fromIANA('private.ulb.ac.be')->withSubDomain('');
+    }
+
     public function testItReturnsTheInstanceWhenTheSLDIsEqual(): void
     {
         $domain = ResolvedDomain::fromICANN('private.ulb.ac.be', 2);

src/Suffix.php

@@ -90,7 +90,7 @@ private static function setDomainName(int|DomainNameProvider|Host|string|Stringa
             $domain = RegisteredName::fromIDNA2008($domain);
         }
 
-        if ('' === $domain->label(0)) {
+        if ($domain->isAbsolute()) {
             throw SyntaxError::dueToInvalidSuffix($domain);
         }