Fixes #612 embed images in emails

.gitignore

@@ -45,7 +45,6 @@ private_key_pkcs8.pem
 JSON.md
 spieldata
 teams-api-calls.md
-.run/
 client/locale_parser.js
 PlayGroundTest.java
 spieldata

.run/BE - InviteServerApplication.run.xml

@@ -0,0 +1,15 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="BE - InviteServerApplication" type="SpringBootApplicationConfigurationType" factoryName="Spring Boot">
+    <module name="invite-server" />
+    <option name="SPRING_BOOT_MAIN_CLASS" value="invite.InviteServerApplication" />
+    <extension name="coverage">
+      <pattern>
+        <option name="PATTERN" value="invite.*" />
+        <option name="ENABLED" value="true" />
+      </pattern>
+    </extension>
+    <method v="2">
+      <option name="Make" enabled="true" />
+    </method>
+  </configuration>
+</component>

.run/BE - MockProvisioningApplication.run.xml

@@ -0,0 +1,9 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="BE - MockProvisioningApplication" type="SpringBootApplicationConfigurationType" factoryName="Spring Boot">
+    <module name="provisioning-mock" />
+    <option name="SPRING_BOOT_MAIN_CLASS" value="provisioning.MockProvisioningApplication" />
+    <method v="2">
+      <option name="Make" enabled="true" />
+    </method>
+  </configuration>
+</component>

.run/FE - Client.run.xml

@@ -0,0 +1,12 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="FE - Client" type="js.build_tools.npm">
+    <package-json value="$PROJECT_DIR$/client/package.json" />
+    <command value="run" />
+    <scripts>
+      <script value="dev" />
+    </scripts>
+    <node-interpreter value="project" />
+    <envs />
+    <method v="2" />
+  </configuration>
+</component>

server/src/main/java/invite/mail/ImageEmbedder.java

@@ -0,0 +1,69 @@
+package invite.mail;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import java.io.InputStream;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.util.Base64;
+import java.util.Optional;
+
+public class ImageEmbedder {
+
+    private static final Log LOG = LogFactory.getLog(ImageEmbedder.class);
+    private static final String DEFAULT_CONTENT_TYPE = "image/png";
+    private static final HttpClient HTTP_CLIENT = HttpClient.newHttpClient();
+    private static final int MAX_IMAGE_BYTES = 1 * 1024 * 1024; // 1 MegaByte
+
+    private ImageEmbedder() {
+    }
+
+    /**
+     * Fetches a remote image and returns it as a data: URL for use in an HTML.
+     *
+     * @param imageUrl the absolute URL of the image to fetch
+     * @return the data: URL, or empty if the image cannot be fetched
+     */
+    public static Optional<String> fetchAsDataUrl(String imageUrl) {
+        try {
+            HttpRequest request = HttpRequest.newBuilder().uri(URI.create(imageUrl)).build();
+            HttpResponse<InputStream> response = HTTP_CLIENT.send(request, HttpResponse.BodyHandlers.ofInputStream());
+
+            Optional<byte[]> body = readBounded(response.body(), imageUrl);
+            if (body.isEmpty()) {
+                return Optional.empty();
+            }
+
+            String contentType = response.headers()
+                    .firstValue("Content-Type")
+                    .orElse(DEFAULT_CONTENT_TYPE);
+
+            return Optional.of(toDataUrl(contentType, body.get()));
+        } catch (Exception e) {
+            LOG.warn(String.format("Error fetching image from %s: %s", imageUrl, e.getMessage()));
+            return Optional.empty();
+        }
+    }
+
+    private static Optional<byte[]> readBounded(InputStream source, String imageUrl) {
+        try (InputStream in = source) {
+            byte[] bytes = in.readNBytes(MAX_IMAGE_BYTES + 1);
+            if (bytes.length > MAX_IMAGE_BYTES) {
+                LOG.warn(String.format("Image at %s exceeds maximum size of %d bytes; aborting download",
+                        imageUrl, MAX_IMAGE_BYTES));
+                return Optional.empty();
+            }
+            return Optional.of(bytes);
+        } catch (Exception e) {
+            LOG.warn(String.format("Error reading image from %s: %s", imageUrl, e.getMessage()));
+            return Optional.empty();
+        }
+    }
+
+    private static String toDataUrl(String contentType, byte[] body) {
+        return "data:" + contentType + ";base64," + Base64.getEncoder().encodeToString(body);
+    }
+}

server/src/main/java/invite/mail/MailBox.java

@@ -2,11 +2,17 @@
 
 import invite.cron.IdPMetaDataResolver;
 import invite.cron.IdentityProvider;
-import invite.model.*;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.github.mustachejava.DefaultMustacheFactory;
 import com.github.mustachejava.MustacheFactory;
+import invite.model.Authority;
+import invite.model.GroupedProviders;
+import invite.model.Invitation;
+import invite.model.Language;
+import invite.model.Provisionable;
+import invite.model.User;
+import invite.model.UserRole;
 import jakarta.mail.MessagingException;
 import jakarta.mail.internet.MimeMessage;
 import lombok.SneakyThrows;
@@ -19,7 +25,11 @@
 
 import java.io.IOException;
 import java.io.StringWriter;
-import java.util.*;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 @SuppressWarnings("unchecked")
@@ -73,7 +83,7 @@ public void sendInviteMail(Provisionable provisionable, Invitation invitation,
                     .map(idp -> idp.getName())
                     .orElse(user.getSchacHomeOrganization()));
             variables.put("institutionLogoUrl", identityProvider
-                    .map(idp -> idp.getLogoUrl())
+                    .flatMap(idp -> ImageEmbedder.fetchAsDataUrl(idp.getLogoUrl()))
                     .orElse(null));
         } else {
             variables.put("institutionName", "SURF");

server/src/test/java/invite/mail/ImageEmbedderTest.java

@@ -0,0 +1,70 @@
+package invite.mail;
+
+import com.github.tomakehurst.wiremock.http.Fault;
+import invite.WireMockExtension;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import java.util.Optional;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
+import static com.github.tomakehurst.wiremock.client.WireMock.get;
+import static com.github.tomakehurst.wiremock.client.WireMock.getRequestedFor;
+import static com.github.tomakehurst.wiremock.client.WireMock.stubFor;
+import static com.github.tomakehurst.wiremock.client.WireMock.urlPathEqualTo;
+import static com.github.tomakehurst.wiremock.client.WireMock.verify;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class ImageEmbedderTest {
+
+    @RegisterExtension
+    WireMockExtension mockServer = new WireMockExtension(8093);
+
+    @Test
+    void fetchAsDataUrl() {
+        // base64 encoding: "iVBORw0KGgo="
+        byte[] pngBytes = {(byte) 0x89, 'P', 'N', 'G', 0x0D, 0x0A, 0x1A, 0x0A};
+        stubFor(get(urlPathEqualTo("/logo.png")).willReturn(aResponse()
+                .withHeader("Content-Type", "image/png")
+                .withBody(pngBytes)));
+
+        Optional<String> dataUrl = ImageEmbedder.fetchAsDataUrl("http://localhost:8093/logo.png");
+
+        assertTrue(dataUrl.isPresent());
+        assertEquals("data:image/png;base64,iVBORw0KGgo=", dataUrl.get());
+        verify(getRequestedFor(urlPathEqualTo("/logo.png")));
+    }
+
+    @Test
+    void fetchAsDataUrlReturnsEmptyWhenImageExceedsMaxSize() {
+        // One byte over the 1 MB MAX_IMAGE_BYTES cap
+        byte[] oversizedBody = new byte[1024 * 1024 + 1];
+        stubFor(get(urlPathEqualTo("/huge.png")).willReturn(aResponse()
+                .withHeader("Content-Type", "image/png")
+                .withBody(oversizedBody)));
+
+        Optional<String> dataUrl = ImageEmbedder.fetchAsDataUrl("http://localhost:8093/huge.png");
+
+        assertTrue(dataUrl.isEmpty());
+        verify(getRequestedFor(urlPathEqualTo("/huge.png")));
+    }
+
+    @Test
+    void fetchAsDataUrlReturnsEmptyOnBodyReadFailure() {
+        stubFor(get(urlPathEqualTo("/broken.png")).willReturn(aResponse()
+                .withFault(Fault.MALFORMED_RESPONSE_CHUNK)));
+
+        Optional<String> dataUrl = ImageEmbedder.fetchAsDataUrl("http://localhost:8093/broken.png");
+
+        assertTrue(dataUrl.isEmpty());
+        verify(getRequestedFor(urlPathEqualTo("/broken.png")));
+    }
+
+    @Test
+    void fetchAsDataUrlReturnsEmptyOnFailure() {
+        Optional<String> dataUrl = ImageEmbedder.fetchAsDataUrl("not a url");
+
+        assertTrue(dataUrl.isEmpty());
+    }
+}