feat: Implement new services required or OpenSSL certificate creation

src/main/java/de/mlessmann/certassist/Constants.java

@@ -0,0 +1,10 @@
+package de.mlessmann.certassist;
+
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public class Constants {
+
+    public static final String CERTASSIST_TMP_PREFIX = "certassist_";
+}

src/main/java/de/mlessmann/certassist/openssl/CertificatePasswordProvider.java

@@ -1,6 +1,6 @@
 package de.mlessmann.certassist.openssl;
 
-public interface CertPasswordProvider {
+public interface CertificatePasswordProvider {
     String generateNewPassword();
 
     String getPasswordFor(String certificateFingerprint);

src/main/java/de/mlessmann/certassist/openssl/OpenSSLCertificateCreator.java

@@ -1,5 +1,7 @@
 package de.mlessmann.certassist.openssl;
 
+import static de.mlessmann.certassist.Constants.CERTASSIST_TMP_PREFIX;
+
 import de.mlessmann.certassist.ExecutableResolver;
 import de.mlessmann.certassist.except.CommandLineOperationException;
 import de.mlessmann.certassist.except.UnresolvableCLIDependency;
@@ -46,7 +48,7 @@ public class OpenSSLCertificateCreator {
     );
 
     private final ExecutableResolver executableResolver;
-    private final CertPasswordProvider passwordProvider;
+    private final CertificatePasswordProvider passwordProvider;
     private final CertificateProvider certificateProvider;
 
     private static String buildSubjectArg(CertificateRequest request) {
@@ -72,7 +74,7 @@ public class OpenSSLCertificateCreator {
         throws CommandLineOperationException, InterruptedException {
         Path tmpDir;
         try {
-            tmpDir = Files.createTempDirectory("certassist");
+            tmpDir = Files.createTempDirectory(CERTASSIST_TMP_PREFIX);
         } catch (IOException e) {
             throw new CommandLineOperationException("Could not create temporary directory for certificate creation", e);
         }

src/main/java/de/mlessmann/certassist/repositories/CertificateRepository.java

@@ -5,4 +5,6 @@ import org.springframework.data.repository.CrudRepository;
 import org.springframework.stereotype.Repository;
 
 @Repository
-public interface CertificateRepository extends CrudRepository<Certificate, String> {}
+public interface CertificateRepository extends CrudRepository<Certificate, String> {
+    Certificate findByFingerprintIs(String fingerprint);
+}

src/main/java/de/mlessmann/certassist/service/CertificateProviderImpl.java

@@ -0,0 +1,68 @@
+package de.mlessmann.certassist.service;
+
+import de.mlessmann.certassist.Constants;
+import de.mlessmann.certassist.DeleteRecursiveFileVisitor;
+import de.mlessmann.certassist.openssl.CertificateProvider;
+import de.mlessmann.certassist.openssl.CertificateUsage;
+import de.mlessmann.certassist.repositories.CertificateRepository;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.OpenOption;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+
+@Service
+@Slf4j
+@RequiredArgsConstructor
+public class CertificateProviderImpl implements CertificateProvider {
+
+    private static final OpenOption[] CREATE_TRUNCATE = new OpenOption[] {
+        StandardOpenOption.CREATE,
+        StandardOpenOption.TRUNCATE_EXISTING,
+    };
+    private final CertificateRepository certificateRepository;
+
+    @Override
+    public CertificateUsage requestCertificateUsage(String fingerprint) {
+        var certFromDB = certificateRepository.findByFingerprintIs(fingerprint);
+        if (certFromDB == null) {
+            throw new IllegalArgumentException("Unknown fingerprint");
+        }
+
+        try {
+            Path tempDirectory = Files.createTempDirectory(Constants.CERTASSIST_TMP_PREFIX);
+            Files.write(tempDirectory.resolve("key.pem"), certFromDB.getPrivateKey(), CREATE_TRUNCATE);
+            Files.write(tempDirectory.resolve("cert.pem"), certFromDB.getCert(), CREATE_TRUNCATE);
+            return new ExtractedCert(tempDirectory, certFromDB.getFingerprint());
+        } catch (IOException e) {
+            // TODO: Better exception definitions
+            throw new RuntimeException("Unable to temporarily store certificate for use.", e);
+        }
+    }
+
+    @Slf4j
+    private record ExtractedCert(Path tempDir, String fingerprint) implements CertificateUsage {
+        @Override
+        public Path certificateKeyPath() {
+            return this.tempDir.resolve("key.pem");
+        }
+
+        @Override
+        public Path certificatePath() {
+            return this.tempDir.resolve("cert.pem");
+        }
+
+        @Override
+        public void close() {
+            try {
+                Files.walkFileTree(this.tempDir, new DeleteRecursiveFileVisitor());
+                Files.deleteIfExists(this.tempDir);
+            } catch (IOException e) {
+                log.error("Unable to clean up temporary directory: " + this.tempDir, e);
+            }
+        }
+    }
+}

src/test/java/de/mlessmann/certassist/TestOpenSSLCertificateCreator.java

@@ -10,11 +10,11 @@ import org.junit.jupiter.api.Test;
 
 class TestOpenSSLCertificateCreator {
 
-    private CertPasswordProvider passwordProvider;
+    private CertificatePasswordProvider passwordProvider;
 
     @BeforeEach
     void setUp() {
-        passwordProvider = mock(CertPasswordProvider.class);
+        passwordProvider = mock(CertificatePasswordProvider.class);
         when(passwordProvider.generateNewPassword()).thenReturn("ABC-123");
     }
 

src/test/java/de/mlessmann/certassist/service/InMemoryCertificatePasswordProvider.java

@@ -0,0 +1,40 @@
+package de.mlessmann.certassist.service;
+
+import de.mlessmann.certassist.openssl.CertificatePasswordProvider;
+import java.security.SecureRandom;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+import org.springframework.stereotype.Service;
+
+@Service
+public class InMemoryCertificatePasswordProvider implements CertificatePasswordProvider {
+
+    private final Map<String, String> passwords = new ConcurrentHashMap<>();
+    private static final String CHARACTERS =
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*()-_=+[]{}|;:,.<>?";
+    private static final int PASSPHRASE_LENGTH = 16;
+
+    @Override
+    public String generateNewPassword() {
+        SecureRandom random = new SecureRandom();
+        StringBuilder passphrase = new StringBuilder(PASSPHRASE_LENGTH);
+        for (int i = 0; i < PASSPHRASE_LENGTH; i++) {
+            passphrase.append(CHARACTERS.charAt(random.nextInt(CHARACTERS.length())));
+        }
+        return passphrase.toString();
+    }
+
+    @Override
+    public String getPasswordFor(String certificateFingerprint) {
+        return Optional.ofNullable(passwords.get(certificateFingerprint)).orElseThrow();
+    }
+
+    @Override
+    public void setPasswordFor(String certificateFingerprint, String password) {
+        Objects.requireNonNull(certificateFingerprint);
+        Objects.requireNonNull(password);
+        passwords.put(certificateFingerprint, password);
+    }
+}