google.registry.util.UrlFetchUtils.java Source code

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Here is the source code for google.registry.util.UrlFetchUtils.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.checkState;
import static com.google.common.io.BaseEncoding.base64;
import static com.google.common.net.HttpHeaders.AUTHORIZATION;
import static com.google.common.net.HttpHeaders.CONTENT_DISPOSITION;
import static com.google.common.net.HttpHeaders.CONTENT_LENGTH;
import static com.google.common.net.HttpHeaders.CONTENT_TYPE;
import static java.lang.String.format;
import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.appengine.api.urlfetch.HTTPHeader;
import com.google.appengine.api.urlfetch.HTTPRequest;
import com.google.appengine.api.urlfetch.HTTPResponse;
import com.google.common.base.Ascii;
import com.google.common.base.Optional;
import com.google.common.base.Strings;
import com.google.common.net.MediaType;
import java.util.Random;

/** Helper methods for the App Engine URL fetch service. */
public final class UrlFetchUtils {

    @NonFinalForTesting
    private static Random random = new Random();

    /** Returns value of first header matching {@code name}. */
    public static Optional<String> getHeaderFirst(HTTPResponse rsp, String name) {
        return getHeaderFirstInternal(rsp.getHeadersUncombined(), name);
    }

    /** Returns value of first header matching {@code name}. */
    public static Optional<String> getHeaderFirst(HTTPRequest req, String name) {
        return getHeaderFirstInternal(req.getHeaders(), name);
    }

    private static Optional<String> getHeaderFirstInternal(Iterable<HTTPHeader> hdrs, String name) {
        name = Ascii.toLowerCase(name);
        for (HTTPHeader header : hdrs) {
            if (Ascii.toLowerCase(header.getName()).equals(name)) {
                return Optional.of(header.getValue());
            }
        }
        return Optional.absent();
    }

    /**
     * Sets payload on request as a {@code multipart/form-data} request.
     *
     * <p>This is equivalent to running the command: {@code curl -F fieldName=@payload.txt URL}
     *
     * @see <a href="http://www.ietf.org/rfc/rfc2388.txt"> RFC2388 - Returning Values from Forms</a>
     */
    public static void setPayloadMultipart(HTTPRequest request, String name, String filename, MediaType contentType,
            String data) {
        String boundary = createMultipartBoundary();
        checkState(!data.contains(boundary), "Multipart data contains autogenerated boundary: %s", boundary);
        StringBuilder multipart = new StringBuilder();
        multipart.append(format("--%s\r\n", boundary));
        multipart.append(
                format("%s: form-data; name=\"%s\"; filename=\"%s\"\r\n", CONTENT_DISPOSITION, name, filename));
        multipart.append(format("%s: %s\r\n", CONTENT_TYPE, contentType.toString()));
        multipart.append("\r\n");
        multipart.append(data);
        multipart.append("\r\n");
        multipart.append(format("--%s--", boundary));
        byte[] payload = multipart.toString().getBytes(UTF_8);
        request.addHeader(new HTTPHeader(CONTENT_TYPE, format("multipart/form-data; boundary=\"%s\"", boundary)));
        request.addHeader(new HTTPHeader(CONTENT_LENGTH, Integer.toString(payload.length)));
        request.setPayload(payload);
    }

    private static String createMultipartBoundary() {
        // Generate 192 random bits (24 bytes) to produce 192/log_2(64) = 192/6 = 32 base64 digits.
        byte[] rand = new byte[24];
        random.nextBytes(rand);
        // Boundary strings can be up to 70 characters long, so use 30 hyphens plus 32 random digits.
        // See https://tools.ietf.org/html/rfc2046#section-5.1.1
        return Strings.repeat("-", 30) + base64().encode(rand);
    }

    /** Sets the HTTP Basic Authentication header on an {@link HTTPRequest}. */
    public static void setAuthorizationHeader(HTTPRequest req, Optional<String> login) {
        if (login.isPresent()) {
            String token = base64().encode(login.get().getBytes(UTF_8));
            req.addHeader(new HTTPHeader(AUTHORIZATION, "Basic " + token));
        }
    }
}