com.zerodeplibs.webpush.ext.jwt.jose4j.Jose4jVAPIDJWTGenerator Maven / Gradle / Ivy

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A sub-module for zerodep-web-push-java. This module provides the JSON Web Token(JWT) generator used for VAPID utilizing [jose4j].
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package com.zerodeplibs.webpush.ext.jwt.jose4j;

import com.zerodeplibs.webpush.jwt.VAPIDJWTCreationException;
import com.zerodeplibs.webpush.jwt.VAPIDJWTGenerator;
import com.zerodeplibs.webpush.jwt.VAPIDJWTParam;
import java.math.BigDecimal;
import java.security.interfaces.ECPrivateKey;
import java.time.Instant;
import java.util.Date;
import org.jose4j.jws.AlgorithmIdentifiers;
import org.jose4j.jws.JsonWebSignature;
import org.jose4j.lang.JoseException;

/**
 * An implementation of {@link VAPIDJWTGenerator}
 * utilizing jose4j.
 *
 * @author Tomoki Sato
 * @see Jose4jVAPIDJWTGeneratorFactory
 */
class Jose4jVAPIDJWTGenerator implements VAPIDJWTGenerator {

    private final ECPrivateKey privateKey;

    Jose4jVAPIDJWTGenerator(ECPrivateKey privateKey) {
        this.privateKey = privateKey;
    }

    /**
     * Generates a JWT used for VAPID.
     *
     * 
     * When the given param has additional claims, these values
     * must be an instance of {@link String}, {@link Boolean},
     * {@link Integer}, {@link Long}, {@link Double}, {@link Date} or {@link Instant}.
     * 
     *
     * @param param parameters used to build the JWT.
     * @return a JWT.
     * @throws IllegalArgumentException if the value of an additional claim
     *                                  is not an instance of a supported type.
     */
    @Override
    public String generate(VAPIDJWTParam param) {

        JsonWebSignature jws = new JsonWebSignature();

        jws.setHeader("typ", "JWT");
        jws.setAlgorithmHeaderValue(AlgorithmIdentifiers.ECDSA_USING_P256_CURVE_AND_SHA256);

        /* Starts building the payload. */
        StringBuilder payloadBuilder = new StringBuilder();
        payloadBuilder.append('{');

        appendStringJsonProp("aud", param.getOrigin(), payloadBuilder);

        payloadBuilder.append(',');
        appendJsonProp("exp", String.valueOf(param.getExpiresAtInSeconds()), payloadBuilder);

        param.getSubject().ifPresent(sub -> {
            payloadBuilder.append(',');
            appendStringJsonProp("sub", sub, payloadBuilder);
        });

        param.forEachAdditionalClaim((name, claim) -> {
            payloadBuilder.append(',');
            appendJsonProp(name, convValue(claim), payloadBuilder);
        });

        payloadBuilder.append('}');
        /* Ends building the payload. */

        jws.setPayload(payloadBuilder.toString());
        jws.setKey(privateKey);

        try {
            return jws.getCompactSerialization();
        } catch (JoseException e) {
            throw VAPIDJWTCreationException.withDefaultMessage(e);
        }
    }

    private void appendStringJsonProp(String name, String value, StringBuilder builder) {
        appendStringJsonToken(name, builder);
        builder.append(':');
        appendStringJsonToken(value, builder);
    }

    private void appendJsonProp(String name, String value, StringBuilder builder) {
        appendStringJsonToken(name, builder);
        builder.append(':');
        builder.append(value);
    }

    private void appendStringJsonToken(String value, StringBuilder builder) {
        builder.append("\"");
        builder.append(value);
        builder.append("\"");
    }

    private String convValue(Object o) {
        if (o == null) {
            return "null";
        }
        if (o instanceof String) {
            return "\"" + o + "\"";
        }
        if (o instanceof Boolean || o instanceof Integer || o instanceof Long) {
            return o.toString();
        }
        if (o instanceof Double) {
            return BigDecimal.valueOf((Double) o).stripTrailingZeros().toPlainString();
        }
        if (o instanceof Date) {
            Date d = (Date) o;
            return String.valueOf(d.getTime() / 1000);
        }
        if (o instanceof Instant) {
            Instant instant = (Instant) o;
            return String.valueOf(instant.toEpochMilli() / 1000);
        }

        throw new IllegalArgumentException(
            "The value of an additional claim must be an instance of "
                + "String, Boolean, Integer, Long, Double, Date or Instant.");
    }
}