61 lines
2.0 KiB
Java
61 lines
2.0 KiB
Java
// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
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//
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// SPDX-License-Identifier: Apache-2.0
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package pgp.wkd;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.io.IOException;
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import java.io.InputStream;
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import java.net.URI;
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/**
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* Abstract class for fetching OpenPGP certificates from the WKD.
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* This class can be extended to fetch files from remote servers using different HTTP clients.
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*/
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public abstract class AbstractWKDFetcher {
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private static final Logger LOGGER = LoggerFactory.getLogger(AbstractWKDFetcher.class);
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/**
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* Attempt to fetch an OpenPGP certificate from the Web Key Directory.
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*
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* @param address WKDAddress object
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* @return input stream containing the certificate in its binary representation
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*
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* @throws IOException in case of an error
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*/
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public InputStream fetch(WKDAddress address) throws IOException {
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URI advanced = address.getAdvancedMethodURI();
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IOException advancedException;
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try {
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return fetchUri(advanced);
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} catch (IOException e) {
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advancedException = e;
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LOGGER.debug("Could not fetch key using advanced method from " + advanced.toString(), advancedException);
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}
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URI direct = address.getDirectMethodURI();
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try {
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return fetchUri(direct);
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} catch (IOException e) {
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// we would like to use addSuppressed eventually, but Android API 10 does not support it
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// e.addSuppressed(advancedException);
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LOGGER.debug("Could not fetch key using direct method from " + direct.toString(), e);
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throw e;
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}
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}
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/**
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* Fetch the contents of the file that the {@link URI} points to from the remote server.
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* @param uri uri
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* @return file contents
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*
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* @throws java.net.ConnectException in case the file or host does not exist
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* @throws IOException in case of an IO-error
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*/
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protected abstract InputStream fetchUri(URI uri) throws IOException;
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}
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