feat: Validate string format 'ipv4'

Author: thced

src/main/java/com/retailsvc/http/validate/DefaultValidator.java

@@ -47,6 +47,9 @@ private record FormatCheck(Predicate<String> isValid, String message) {}
 
   private static final Pattern EMAIL = Pattern.compile("^[^\\s@]+@[^\\s@]+\\.[^\\s@]+$");
 
+  private static final Pattern IPV4 =
+      Pattern.compile("^((25[0-5]|2[0-4]\\d|1?\\d?\\d)\\.){3}(25[0-5]|2[0-4]\\d|1?\\d?\\d)$");
+
   private static final Pattern HOSTNAME =
       Pattern.compile(
           "^(?=.{1,253}$)([a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)"
@@ -65,7 +68,8 @@ private record FormatCheck(Predicate<String> isValid, String message) {}
               new FormatCheck(DefaultValidator::isUriReference, "not a valid uri-reference")),
           Map.entry(
               "hostname",
-              new FormatCheck(s -> HOSTNAME.matcher(s).matches(), "not a valid hostname")));
+              new FormatCheck(s -> HOSTNAME.matcher(s).matches(), "not a valid hostname")),
+          Map.entry("ipv4", new FormatCheck(s -> IPV4.matcher(s).matches(), "not a valid ipv4")));
 
   private final Function<String, Schema> refResolver;
   private final ConcurrentMap<String, Pattern> compiledPatterns = new ConcurrentHashMap<>();

src/test/java/com/retailsvc/http/validate/StringIntegerNumberTest.java

@@ -116,6 +116,20 @@ void stringFormatHostname() {
         .isEqualTo("format");
   }
 
+  @Test
+  void stringFormatIpv4() {
+    StringSchema s = new StringSchema(Set.of(TypeName.STRING), null, null, null, "ipv4", null);
+    assertThatCode(() -> v.validate("192.168.0.1", s, "/v")).doesNotThrowAnyException();
+    assertThatCode(() -> v.validate("0.0.0.0", s, "/v")).doesNotThrowAnyException();
+    assertThatCode(() -> v.validate("255.255.255.255", s, "/v")).doesNotThrowAnyException();
+    assertThatThrownBy(() -> v.validate("256.0.0.1", s, "/v"))
+        .extracting(t -> ((ValidationException) t).error().keyword())
+        .isEqualTo("format");
+    assertThatThrownBy(() -> v.validate("1.2.3", s, "/v"))
+        .extracting(t -> ((ValidationException) t).error().keyword())
+        .isEqualTo("format");
+  }
+
   @Test
   void integerWithMinMax() {
     IntegerSchema s =