Create basic WKDCLI implementation

wkd-java-cli/build.gradle

@@ -16,12 +16,37 @@ dependencies {
     testImplementation "org.junit.jupiter:junit-jupiter-api:$junitVersion"
     testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junitVersion"
 
+    // https://todd.ginsberg.com/post/testing-system-exit/
+    testImplementation 'com.ginsberg:junit5-system-exit:1.1.2'
+    testImplementation 'org.mockito:mockito-core:4.3.1'
+
+    implementation("org.pgpainless:pgpainless-core:1.1.0")
     implementation project(':wkd-java')
+    implementation "info.picocli:picocli:4.6.3"
 
     // Logging
     testImplementation "ch.qos.logback:logback-classic:$logbackVersion"
+    implementation 'org.slf4j:slf4j-nop:1.7.36'
 }
 
 test {
     useJUnitPlatform()
 }
+
+
+mainClassName = 'pgp.wkd.cli.WKDCLI'
+
+jar {
+    duplicatesStrategy(DuplicatesStrategy.EXCLUDE)
+    manifest {
+        attributes 'Main-Class': "$mainClassName"
+    }
+
+    from {
+        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
+    } {
+        exclude "META-INF/*.SF"
+        exclude "META-INF/*.DSA"
+        exclude "META-INF/*.RSA"
+    }
+}

wkd-java-cli/src/main/java/pgp/wkd/cli/MissingUserIdException.java

@@ -0,0 +1,12 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package pgp.wkd.cli;
+
+public class MissingUserIdException extends Exception {
+
+    public MissingUserIdException() {
+        super();
+    }
+}

wkd-java-cli/src/main/java/pgp/wkd/cli/WKDCLI.java

@@ -4,6 +4,27 @@
 
 package pgp.wkd.cli;
 
+import pgp.wkd.cli.command.Fetch;
+import picocli.CommandLine;
+
+@CommandLine.Command(
+        subcommands = {
+                CommandLine.HelpCommand.class,
+                Fetch.class
+        }
+)
 public class WKDCLI {
 
+    public static void main(String[] args) {
+        int exitCode = execute(args);
+        if (exitCode != 0) {
+            System.exit(exitCode);
+        }
+    }
+
+    public static int execute(String[] args) {
+        return new CommandLine(WKDCLI.class)
+                .setCommandName("wkdcli")
+                .execute(args);
+    }
 }

wkd-java-cli/src/main/java/pgp/wkd/cli/command/Fetch.java

@@ -0,0 +1,88 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package pgp.wkd.cli.command;
+
+import org.bouncycastle.bcpg.ArmoredOutputStream;
+import org.bouncycastle.openpgp.PGPPublicKeyRing;
+import org.pgpainless.PGPainless;
+import org.pgpainless.key.info.KeyRingInfo;
+import pgp.wkd.IWKDFetcher;
+import pgp.wkd.JavaHttpRequestWKDFetcher;
+import pgp.wkd.WKDAddress;
+import pgp.wkd.WKDAddressHelper;
+import pgp.wkd.cli.MissingUserIdException;
+import picocli.CommandLine;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.List;
+
+@CommandLine.Command(
+        name = "fetch",
+        description = "Fetch an OpenPGP Certificate via the Web Key Directory"
+)
+public class Fetch implements Runnable {
+
+    @CommandLine.Parameters(
+            index = "0",
+            arity = "1",
+            paramLabel = "USERID",
+            description = "Certificate User-ID"
+    )
+    String userId;
+
+    @CommandLine.Option(
+            names = {"-a", "--armor"},
+            description = "ASCII Armor the output"
+    )
+    boolean armor = false;
+
+    IWKDFetcher fetcher = new JavaHttpRequestWKDFetcher();
+
+    @Override
+    public void run() {
+        String email;
+        try {
+            email = WKDAddressHelper.emailFromUserId(userId);
+        } catch (IllegalArgumentException e) {
+            email = userId;
+        }
+
+        WKDAddress address = WKDAddress.fromEmail(email);
+        try (InputStream inputStream = fetcher.fetch(address)) {
+            PGPPublicKeyRing cert = PGPainless.readKeyRing().publicKeyRing(inputStream);
+            KeyRingInfo info = PGPainless.inspectKeyRing(cert);
+
+            List<String> userIds = info.getValidAndExpiredUserIds();
+            boolean containsEmail = false;
+            for (String certUserId : userIds) {
+                if (certUserId.contains("<" + email + ">") || certUserId.equals(email)) {
+                    containsEmail = true;
+                    break;
+                }
+            }
+            if (!containsEmail) {
+                throw new MissingUserIdException();
+            }
+
+            if (armor) {
+                OutputStream out = new ArmoredOutputStream(System.out);
+                cert.encode(out);
+                out.close();
+            } else {
+                cert.encode(System.out);
+            }
+
+        } catch (IOException e) {
+            System.err.println("Could not fetch certificate.");
+            e.printStackTrace();
+            System.exit(1);
+        } catch (MissingUserIdException e) {
+            System.err.println("Fetched certificate does not contain email address " + email);
+            System.exit(1);
+        }
+    }
+}

wkd-java-cli/src/main/java/pgp/wkd/cli/command/package-info.java

@@ -0,0 +1,8 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+/**
+ * Subcommands of the WKDCLI tool.
+ */
+package pgp.wkd.cli.command;

wkd-java-cli/src/main/java/pgp/wkd/cli/package-info.java

@@ -0,0 +1,8 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+/**
+ * Command Line Interface for fetching OpenPGP Certificates from the Web Key Directory.
+ */
+package pgp.wkd.cli;