google.registry.util.DomainNameUtils.java Source code

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Here is the source code for google.registry.util.DomainNameUtils.java

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// Copyright 2016 The Nomulus Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package google.registry.util;

import static com.google.common.base.Preconditions.checkArgument;
import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;

import com.google.common.base.Ascii;
import com.google.common.base.Strings;
import com.google.common.net.InternetDomainName;

/** Utility methods related to domain names. */
public final class DomainNameUtils {

    /** Prefix for unicode domain name parts. */
    public static final String ACE_PREFIX = "xn--";
    public static final String ACE_PREFIX_REGEX = "^xn--";

    /** Checks whether "name" is a strict subdomain of "potentialParent". */
    public static boolean isUnder(InternetDomainName name, InternetDomainName potentialParent) {
        int numNameParts = name.parts().size();
        int numParentParts = potentialParent.parts().size();
        return numNameParts > numParentParts && name.parts().subList(numNameParts - numParentParts, numNameParts)
                .equals(potentialParent.parts());
    }

    /** Canonicalizes a domain name by lowercasing and converting unicode to punycode. */
    public static String canonicalizeDomainName(String label) {
        return Idn.toASCII(Ascii.toLowerCase(label));
    }

    /**
     * Returns the canonicalized TLD part of a valid fully-qualified domain name by stripping off the
     * leftmost part.
     *
     * <p>This method should not be called for subdomains.
     *
     * <p>This function is compatible with multi-part tlds, e.g. {@code co.uk}. This function will
     * also work on domains for which the registry is not authoritative. If you are certain that the
     * input will be under a TLD this registry controls, then it is preferable to use
     * {@link google.registry.model.registry.Registries#findTldForName(InternetDomainName)
     * Registries#findTldForName}, which will work on hostnames in addition to domains.
     *
     * @param fullyQualifiedDomainName must be a punycode SLD (not a host or unicode)
     * @throws IllegalArgumentException if there is no TLD
     */
    public static String getTldFromDomainName(String fullyQualifiedDomainName) {
        checkArgument(!Strings.isNullOrEmpty(fullyQualifiedDomainName),
                "secondLevelDomainName cannot be null or empty");
        return getTldFromDomainName(InternetDomainName.from(fullyQualifiedDomainName));
    }

    /**
     * Returns the canonicalized TLD part of a valid fully-qualified domain name by stripping off the
     * leftmost part.
     *
     * <p>This function is compatible with multi-part TLDs and should not be called with subdomains.
     *
     * @throws IllegalArgumentException if there is no TLD
     */
    public static String getTldFromDomainName(InternetDomainName domainName) {
        checkArgumentNotNull(domainName);
        checkArgument(domainName.hasParent(), "secondLevelDomainName does not have a TLD");
        return domainName.parent().toString();
    }

    private DomainNameUtils() {
    }
}