Replace use of commons-validator

CHANGELOG.md

@@ -1,6 +1,15 @@
 CHANGELOG
 =========
 
+3.8.0
+------------------
+
+* `commons-validator` has been removed as a dependency. This module now does
+  its own email and domain name validation. This was done to reduce the number
+  of dependencies and any security vulnerabilities in them. The new email
+  validation of the local part is somewhat more lax than the previous
+  validation.
+
 3.7.2 (2025-05-28)
 ------------------
 

pom.xml

@@ -62,11 +62,6 @@
             <artifactId>geoip2</artifactId>
             <version>4.3.1</version>
         </dependency>
-        <dependency>
-            <groupId>commons-validator</groupId>
-            <artifactId>commons-validator</artifactId>
-            <version>1.9.0</version>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter</artifactId>

src/main/java/com/maxmind/minfraud/request/Email.java

@@ -13,8 +13,6 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.regex.Pattern;
-import org.apache.commons.validator.routines.DomainValidator;
-import org.apache.commons.validator.routines.EmailValidator;
 
 /**
  * The email information for the transaction.
@@ -28,6 +26,9 @@ public final class Email extends AbstractModel {
     private static final Map<String, String> equivalentDomains;
     private static final Map<String, Boolean> fastmailDomains;
     private static final Map<String, Boolean> yahooDomains;
+    private static final Pattern DOMAIN_LABEL_PATTERN = Pattern.compile(
+        "^[a-zA-Z0-9]$|^[a-zA-Z0-9][a-zA-Z0-9\\-]*[a-zA-Z0-9]$"
+    );
     private static final Pattern DOT_PATTERN = Pattern.compile("\\.");
     private static final Pattern TRAILING_DOT_PATTERN = Pattern.compile("\\.+$");
     private static final Pattern REPEAT_COM_PATTERN = Pattern.compile("(?:\\.com){2,}$");
@@ -338,7 +339,7 @@ public Builder(boolean enableValidation) {
          * @throws IllegalArgumentException when address is not a valid email address.
          */
         public Email.Builder address(String address) {
-            if (enableValidation && !EmailValidator.getInstance().isValid(address)) {
+            if (enableValidation && !isValidEmail(address)) {
                 throw new IllegalArgumentException(
                     "The email address " + address + " is not valid.");
             }
@@ -373,7 +374,7 @@ public Email.Builder hashAddress() {
          * @throws IllegalArgumentException when domain is not a valid domain.
          */
         public Email.Builder domain(String domain) {
-            if (enableValidation && !DomainValidator.getInstance().isValid(domain)) {
+            if (enableValidation && !isValidDomain(domain)) {
                 throw new IllegalArgumentException("The email domain " + domain + " is not valid.");
             }
             this.domain = domain;
@@ -458,6 +459,34 @@ private String cleanAddress(String address) {
         return localPart + "@" + domain;
     }
 
+    private static boolean isValidEmail(String email) {
+        if (email == null || email.isEmpty()) {
+            return false;
+        }
+
+        // RFC 5321 the forward path limits the mailbox to 254 characters
+        // even though a domain can be 255 and the local part 64
+        if (email.length() > 254) {
+            return false;
+        }
+
+        int atIndex = email.lastIndexOf('@');
+        if (atIndex <= 0) {
+            return false;
+        }
+
+        String localPart = email.substring(0, atIndex);
+        String domainPart = email.substring(atIndex + 1);
+
+        // The local-part has a maximum length of 64 characters.
+        if (localPart.length() > 64) {
+            return false;
+        }
+
+        return isValidDomain(domainPart);
+    }
+
+
     private String cleanDomain(String domain) {
         if (domain == null) {
             return null;
@@ -491,6 +520,49 @@ private String cleanDomain(String domain) {
         return domain;
     }
 
+    private static boolean isValidDomain(String domain) {
+        if (domain == null || domain.isEmpty()) {
+            return false;
+        }
+
+        String asciiDomain;
+        try {
+            asciiDomain = IDN.toASCII(domain);
+        } catch (IllegalArgumentException e) {
+            return false;
+        }
+
+        if (domain.endsWith(".")) {
+            domain = domain.substring(0, domain.length() - 1);
+        }
+
+        if (asciiDomain.length() > 255) {
+            return false;
+        }
+
+        String[] labels = asciiDomain.split("\\.");
+
+        if (labels.length < 2) {
+            return false;
+        }
+
+        for (String label : labels) {
+            if (!isValidDomainLabel(label)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private static boolean isValidDomainLabel(String label) {
+        if (label == null || label.isEmpty() || label.length() > 63) {
+            return false;
+        }
+
+        return DOMAIN_LABEL_PATTERN.matcher(label).matches();
+    }
+
     /**
      * @return The domain of the email address used in the transaction.
      */

src/main/java/module-info.java

@@ -7,7 +7,6 @@
     requires com.fasterxml.jackson.databind;
     requires com.fasterxml.jackson.datatype.jsr310;
     requires transitive com.maxmind.geoip2;
-    requires org.apache.commons.validator;
     requires java.net.http;
 
     exports com.maxmind.minfraud;

src/test/java/com/maxmind/minfraud/request/EmailTest.java

@@ -4,6 +4,7 @@
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
+
 import com.maxmind.minfraud.request.Email.Builder;
 import java.math.BigInteger;
 import java.nio.charset.StandardCharsets;
@@ -12,6 +13,8 @@
 import java.util.HashMap;
 import java.util.Map;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 
 public class EmailTest {
 
@@ -242,11 +245,26 @@ private String toMD5(String s) throws NoSuchAlgorithmException {
         return String.format("%032x", i);
     }
 
-    @Test
-    public void testInvalidAddress() {
+    @ParameterizedTest(name = "Run #{index}: email = \"{0}\"")
+    @ValueSource(strings = {
+            "test.com",
+            "test@",
+            "@test.com",
+            "",
+            "  ",
+            "test@test com.com",
+            "test@test_domain.com",
+            "test@-test.com",
+            "test@test-.com",
+            "test@.test.com",
+            "test@test..com",
+            "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa@test.com",
+            "test@aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.com"
+    })
+    void testInvalidAddresses(String invalidAddress) {
         assertThrows(
             IllegalArgumentException.class,
-            () -> new Builder().address("a@test@test.org").build()
+            () -> new Builder().address(invalidAddress).build()
         );
     }
 
@@ -264,11 +282,32 @@ public void testDomainWithoutValidation() {
         assertEquals(domain, email.getDomain());
     }
 
-    @Test
-    public void testInvalidDomain() {
+    @ParameterizedTest(name = "Run #{index}: domain = \"{0}\"")
+    @ValueSource(strings = {
+            "example",
+            "",
+            "   ",
+            " domain.com",
+            "domain.com ",
+            "domain com.com",
+            "domain_name.com",
+            "domain$.com",
+            "-domain.com",
+            "domain-.com",
+            "domain..com",
+            ".domain.com",
+            "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.com",
+            "a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a" +
+            ".a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a" +
+            ".a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a" +
+            ".a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a.a" +
+            ".com",
+            "xn--.com"
+    })
+    void testInvalidDomains(String invalidDomain) {
         assertThrows(
             IllegalArgumentException.class,
-            () -> new Builder().domain(" domain.com").build()
+            () -> new Builder().domain(invalidDomain).build()
         );
     }
 }