Initial commit

pgp-cert-d-java/src/main/java/pgp/cert_d/FilenameResolver.java

@@ -0,0 +1,60 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package pgp.cert_d;
+
+import pgp.certificate_store.exception.BadNameException;
+
+import java.io.File;
+import java.util.regex.Pattern;
+
+public class FilenameResolver {
+
+    private final File baseDirectory;
+    private final Pattern openPgpV4FingerprintPattern = Pattern.compile("^[a-f0-9]{40}$");
+
+    public FilenameResolver(File baseDirectory) {
+        this.baseDirectory = baseDirectory;
+    }
+
+    public File getBaseDirectory() {
+        return baseDirectory;
+    }
+
+    /**
+     * Calculate the file location for the certificate addressed by the given
+     * lowercase hexadecimal OpenPGP fingerprint.
+     *
+     * @param fingerprint fingerprint
+     * @return absolute certificate file location
+     * @throws BadNameException
+     */
+    public File getCertFileByFingerprint(String fingerprint) throws BadNameException {
+        if (!isFingerprint(fingerprint)) {
+            throw new BadNameException();
+        }
+
+        // is fingerprint
+        File subdirectory = new File(getBaseDirectory(), fingerprint.substring(0, 2));
+        File file = new File(subdirectory, fingerprint.substring(2));
+        return file;
+    }
+
+    public File getCertFileBySpecialName(String specialName) throws BadNameException {
+        if (!isSpecialName(specialName)) {
+            throw new BadNameException();
+        }
+
+        return new File(getBaseDirectory(), specialName);
+    }
+
+    private boolean isFingerprint(String fingerprint) {
+        return openPgpV4FingerprintPattern.matcher(fingerprint).matches();
+    }
+
+    private boolean isSpecialName(String specialName) {
+        return SpecialNames.lookupSpecialName(specialName) != null;
+    }
+
+}