#260: dynamic datasource resolution for html embedded images

Author: bbottema

modules/core-module/src/main/java/org/simplejavamail/api/email/EmailPopulatingBuilder.java

@@ -20,6 +20,9 @@
 import java.util.Date;
 import java.util.List;
 import java.util.Map;
+import java.util.regex.Pattern;
+
+import static java.util.regex.Pattern.compile;
 
 /**
  * Fluent interface Builder for populating {@link Email} instances. An instance of this builder can only be obtained through one of the builder
@@ -30,6 +33,13 @@
  */
 @Cli.BuilderApiNode(builderApiType = CliBuilderApiType.EMAIL)
 public interface EmailPopulatingBuilder {
+
+	/**
+	 * Regular Expression to find all {@code <img src="...">} entries in an HTML document.It needs to cater for various things, like more whitespaces including newlines on any place, HTML is not case
+	 * sensitive and there can be arbitrary text between "IMG" and "SRC" like IDs and other things.
+	 */
+	Pattern IMG_SRC_PATTERN = compile("(?<imageTagStart><[Ii][Mm][Gg]\\s*[^>]*?\\s+[Ss][Rr][Cc]\\s*=\\s*[\"'])(?<src>[^\"']+?)(?<imageSrcEnd>[\"'])");
+
 	/**
 	 * Validated DKIM values and then delegates to {@link Email#Email(EmailPopulatingBuilder)} with <code>this</code> as argument.
 	 */
@@ -857,20 +867,26 @@ public interface EmailPopulatingBuilder {
 	 * Sets the base folder used when resolving images sources in HTML text. Without this, the folder needs to be an absolute path (or a classpath/url resource).
 	 * <p>
 	 * Generally you would manually use src="cid:image_name", but files and url's will be located as well dynamically.
+	 *
+	 * @param embeddedImageBaseDir The base folder used when resolving images sources in HTML text.
 	 */
 	EmailPopulatingBuilder withEmbeddedImageBaseDir(@NotNull final String embeddedImageBaseDir);
 
 	/**
 	 * Sets the classpath base used when resolving images sources in HTML text. Without this, the resource needs to be an absolute path (or a file/url resource).
 	 * <p>
 	 * Generally you would manually use src="cid:image_name", but files and url's will be located as well dynamically.
+	 *
+	 * @param embeddedImageBaseClassPath The classpath base used when resolving images sources in HTML text.
 	 */
 	EmailPopulatingBuilder withEmbeddedImageBaseClassPath(@NotNull final String embeddedImageBaseClassPath);
 
 	/**
 	 * Sets the base URL used when resolving images sources in HTML text. Without this, the resource needs to be an absolute URL (or a file/classpath resource).
 	 * <p>
 	 * Generally you would manually use src="cid:image_name", but files and url's will be located as well dynamically.
+	 *
+	 * @param embeddedImageBaseUrl The base URL used when resolving images sources in HTML text.
 	 */
 	EmailPopulatingBuilder withEmbeddedImageBaseUrl(@NotNull final URL embeddedImageBaseUrl);
 

modules/core-module/src/main/java/org/simplejavamail/config/ConfigLoader.java

@@ -70,6 +70,9 @@
  * <li>simplejavamail.smime.signing.key_alias</li>
  * <li>simplejavamail.smime.signing.key_password</li>
  * <li>simplejavamail.smime.encryption.certificate</li>
+ * <li>simplejavamail.embeddedimages.dynamicresolution.base.dir</li>
+ * <li>simplejavamail.embeddedimages.dynamicresolution.base.url</li>
+ * <li>simplejavamail.embeddedimages.dynamicresolution.base.classpath</li>
  * </ul>
  */
 public final class ConfigLoader {
@@ -144,7 +147,10 @@ public enum Property {
 		SMIME_SIGNING_KEYSTORE_PASSWORD("simplejavamail.smime.signing.keystore_password"),
 		SMIME_SIGNING_KEY_ALIAS("simplejavamail.smime.signing.key_alias"),
 		SMIME_SIGNING_KEY_PASSWORD("simplejavamail.smime.signing.key_password"),
-		SMIME_ENCRYPTION_CERTIFICATE("simplejavamail.smime.encryption.certificate");
+		SMIME_ENCRYPTION_CERTIFICATE("simplejavamail.smime.encryption.certificate"),
+		EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_DIR("simplejavamail.embeddedimages.dynamicresolution.base.dir"),
+		EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_URL("simplejavamail.embeddedimages.dynamicresolution.base.url"),
+		EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_CLASSPATH("simplejavamail.embeddedimages.dynamicresolution.base.classpath");
 
 		private final String key;
 

modules/core-module/src/main/java/org/simplejavamail/internal/util/MiscUtil.java

@@ -5,10 +5,15 @@
 import org.jetbrains.annotations.Nullable;
 import org.simplejavamail.api.email.Recipient;
 
+import javax.activation.DataSource;
+import javax.activation.FileDataSource;
+import javax.activation.FileTypeMap;
+import javax.activation.URLDataSource;
 import javax.mail.Message.RecipientType;
 import javax.mail.internet.AddressException;
 import javax.mail.internet.InternetAddress;
 import javax.mail.internet.MimeUtility;
+import javax.mail.util.ByteArrayDataSource;
 import java.io.BufferedInputStream;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -19,22 +24,26 @@
 import java.io.UnsupportedEncodingException;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
+import java.net.URL;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.Random;
 import java.util.regex.Pattern;
 
 import static java.lang.Integer.toHexString;
 import static java.lang.String.format;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.Arrays.asList;
 import static java.util.regex.Pattern.compile;
+import static java.util.regex.Pattern.quote;
 import static org.simplejavamail.internal.util.Preconditions.assumeTrue;
 import static org.simplejavamail.internal.util.Preconditions.checkNonEmptyArgument;
+import static org.simplejavamail.internal.util.SimpleOptional.ofNullable;
 
 public final class MiscUtil {
 
@@ -44,6 +53,10 @@ public final class MiscUtil {
 	private static final Pattern TRAILING_TOKEN_DELIMITER_PATTERN = compile("<\\|>$");
 	private static final Pattern TOKEN_DELIMITER_PATTERN = compile("\\s*<\\|>\\s*");
 
+	private static final Pattern ABSOLUTE_URL_PATTERN = compile(format("^(%s|%s|%s).*", quote("http://"), quote("https://"), quote("file:/")));
+
+	private static final Random RANDOM = new Random();
+
 	@SuppressFBWarnings(value = "NP_PARAMETER_MUST_BE_NONNULL_BUT_MARKED_AS_NULLABLE")
 	public static <T> T checkNotNull(final @Nullable T value, final @Nullable String msg) {
 		if (value == null) {
@@ -263,4 +276,72 @@ public static ByteArrayInputStream copyInputstream(InputStream input) {
 
 		return new ByteArrayInputStream(baos.toByteArray());
 	}
+
+	@Nullable
+	public static  DataSource tryResolveFileDataSource(@Nullable final String baseDir, @Nullable final String baseClassPath, @NotNull final String srcLocation)
+			throws IOException {
+		DataSource fileSource = tryResolveFileDataSourceFromDisk(baseDir, srcLocation);
+		return (fileSource != null) ? fileSource : tryResolveFileDataSourceFromClassPath(baseClassPath, srcLocation);
+	}
+
+	@Nullable
+	private static DataSource tryResolveFileDataSourceFromDisk(final @Nullable String baseDir, final @NotNull String srcLocation) {
+		File file = new File(srcLocation);
+		if (!file.exists() && !file.isAbsolute()) {
+			file = new File(ofNullable(baseDir).orElse("."), srcLocation);
+		}
+		if (file.exists()) {
+			return new FileDataSource(file);
+		}
+		return null;
+	}
+
+	@Nullable
+	private static DataSource tryResolveFileDataSourceFromClassPath(final @Nullable String baseClassPath, final @NotNull String srcLocation)
+			throws IOException {
+		final String resourceName = (ofNullable(baseClassPath).orElse("") + srcLocation).replaceAll("//", "/");
+		final InputStream is = MiscUtil.class.getResourceAsStream(resourceName);
+
+		if (is != null) {
+			try {
+				final String mimeType = FileTypeMap.getDefaultFileTypeMap().getContentType(srcLocation);
+				final ByteArrayDataSource ds = new ByteArrayDataSource(is, mimeType);
+				// EMAIL-125: set the name of the DataSource to the normalized resource URL similar to other DataSource implementations, e.g. FileDataSource, URLDataSource
+				ds.setName(MiscUtil.class.getResource(resourceName).toString());
+				return ds;
+			} finally {
+				is.close();
+			}
+		}
+		return null;
+	}
+
+	@NotNull
+	public static DataSource resolveUrlDataSource(@Nullable final URL baseUrl, @NotNull final String srcLocation)
+			throws IOException {
+		final URL url = (valueNullOrEmpty(baseUrl) || ABSOLUTE_URL_PATTERN.matcher(srcLocation).matches())
+				? new URL(srcLocation)
+				: new URL(baseUrl, srcLocation.replaceAll("&amp;", "&"));
+
+		DataSource result = new URLDataSource(url);
+		result.getInputStream();
+		return result;
+	}
+
+	public static String randomCid10() {
+		final int start = ' ';
+		final int end = 'z' + 1;
+		final int gap = end - start;
+
+		final StringBuilder buffer = new StringBuilder();
+
+		while (buffer.length() < 10) {
+			final char ch = (char) (RANDOM.nextInt(gap) + start);
+			if (Character.isLetter(ch)) {
+				buffer.append(ch);
+			}
+		}
+
+		return buffer.toString().toLowerCase();
+	}
 }

modules/simple-java-mail/src/main/java/org/simplejavamail/email/internal/EmailException.java

@@ -12,6 +12,7 @@ class EmailException extends MailException {
 	static final String ERROR_READING_FROM_FILE = "Error reading from file: %s";
 	static final String ERROR_READING_FROM_PEM_INPUTSTREAM = "Was unable to convert PEM data to X509 certificate";
 	static final String ERROR_LOADING_PROVIDER_FOR_SMIME_SUPPORT = "Unable to load certificate (missing bouncy castle), is the S/MIME module on the class path?";
+	static final String ERROR_RESOLVING_IMAGE_DATASOURCE = "Unable to dynamically resolve data source for the following image src: %s";
 
 	EmailException(@SuppressWarnings("SameParameterValue") final String message) {
 		super(message);

modules/simple-java-mail/src/main/java/org/simplejavamail/email/internal/EmailPopulatingBuilderImpl.java

@@ -38,11 +38,13 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.regex.Matcher;
 
 import static java.lang.String.format;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
+import static java.util.regex.Matcher.quoteReplacement;
 import static javax.mail.Message.RecipientType.BCC;
 import static javax.mail.Message.RecipientType.CC;
 import static javax.mail.Message.RecipientType.TO;
@@ -59,6 +61,9 @@
 import static org.simplejavamail.config.ConfigLoader.Property.DEFAULT_SUBJECT;
 import static org.simplejavamail.config.ConfigLoader.Property.DEFAULT_TO_ADDRESS;
 import static org.simplejavamail.config.ConfigLoader.Property.DEFAULT_TO_NAME;
+import static org.simplejavamail.config.ConfigLoader.Property.EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_CLASSPATH;
+import static org.simplejavamail.config.ConfigLoader.Property.EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_DIR;
+import static org.simplejavamail.config.ConfigLoader.Property.EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_URL;
 import static org.simplejavamail.config.ConfigLoader.Property.SMIME_ENCRYPTION_CERTIFICATE;
 import static org.simplejavamail.config.ConfigLoader.Property.SMIME_SIGNING_KEYSTORE;
 import static org.simplejavamail.config.ConfigLoader.Property.SMIME_SIGNING_KEYSTORE_PASSWORD;
@@ -70,10 +75,14 @@
 import static org.simplejavamail.email.internal.EmailException.ERROR_LOADING_PROVIDER_FOR_SMIME_SUPPORT;
 import static org.simplejavamail.email.internal.EmailException.ERROR_READING_FROM_FILE;
 import static org.simplejavamail.email.internal.EmailException.ERROR_READING_FROM_PEM_INPUTSTREAM;
+import static org.simplejavamail.email.internal.EmailException.ERROR_RESOLVING_IMAGE_DATASOURCE;
 import static org.simplejavamail.email.internal.EmailException.NAME_MISSING_FOR_EMBEDDED_IMAGE;
 import static org.simplejavamail.internal.smimesupport.SmimeRecognitionUtil.isGeneratedSmimeMessageId;
 import static org.simplejavamail.internal.util.MiscUtil.defaultTo;
 import static org.simplejavamail.internal.util.MiscUtil.extractEmailAddresses;
+import static org.simplejavamail.internal.util.MiscUtil.randomCid10;
+import static org.simplejavamail.internal.util.MiscUtil.resolveUrlDataSource;
+import static org.simplejavamail.internal.util.MiscUtil.tryResolveFileDataSource;
 import static org.simplejavamail.internal.util.MiscUtil.valueNullOrEmpty;
 import static org.simplejavamail.internal.util.Preconditions.assumeNonNull;
 import static org.simplejavamail.internal.util.Preconditions.checkNonEmptyArgument;
@@ -322,6 +331,15 @@ public class EmailPopulatingBuilderImpl implements InternalEmailPopulatingBuilde
 			if (hasProperty(SMIME_ENCRYPTION_CERTIFICATE)) {
 				encryptWithSmime(assumeNonNull(getStringProperty(SMIME_ENCRYPTION_CERTIFICATE)));
 			}
+			if (hasProperty(EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_DIR)) {
+				withEmbeddedImageBaseDir(assumeNonNull(getStringProperty(EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_DIR)));
+			}
+			if (hasProperty(EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_URL)) {
+				withEmbeddedImageBaseDir(assumeNonNull(getStringProperty(EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_URL)));
+			}
+			if (hasProperty(EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_CLASSPATH)) {
+				withEmbeddedImageBaseDir(assumeNonNull(getStringProperty(EMBEDDEDIMAGES_DYNAMICRESOLUTION_BASE_CLASSPATH)));
+			}
 		}
 	}
 
@@ -332,6 +350,7 @@ public class EmailPopulatingBuilderImpl implements InternalEmailPopulatingBuilde
 	@Cli.ExcludeApi(reason = "This API is specifically for Java use")
 	public Email buildEmail() {
 		validateDkim();
+		resolveDynamicEmbeddedImageDataSources();
 		return new Email(this);
 	}
 
@@ -343,6 +362,41 @@ private void validateDkim() {
 		}
 	}
 
+	private void resolveDynamicEmbeddedImageDataSources() {
+		if (this.textHTML != null) {
+			final Map<String, String> generatedCids = new HashMap<>();
+			final StringBuffer stringBuffer = new StringBuffer();
+
+			final Matcher matcher = IMG_SRC_PATTERN.matcher(this.textHTML);
+			while (matcher.find()) {
+				final String srcLocation = matcher.group("src");
+				if (!srcLocation.startsWith("cid:")) {
+					if (!generatedCids.containsKey(srcLocation)) {
+						generatedCids.put(srcLocation, randomCid10());
+						withEmbeddedImage(generatedCids.get(srcLocation), resolveDynamicEmbeddedImageDataSource(srcLocation));
+					}
+					final String imgSrcReplacement = matcher.group("imageTagStart") + "cid:" + generatedCids.get(srcLocation) + matcher.group("imageSrcEnd");
+					matcher.appendReplacement(stringBuffer, quoteReplacement(imgSrcReplacement));
+				}
+			}
+			matcher.appendTail(stringBuffer);
+
+			this.textHTML = stringBuffer.toString();
+		}
+	}
+
+	private DataSource resolveDynamicEmbeddedImageDataSource(@NotNull final String srcLocation) {
+		try {
+			DataSource resolvedDataSource = tryResolveFileDataSource(embeddedImageBaseDir, embeddedImageBaseClassPath, srcLocation);
+			if (resolvedDataSource == null) {
+				resolvedDataSource = resolveUrlDataSource(embeddedImageBaseUrl, srcLocation);
+			}
+			return resolvedDataSource;
+		} catch (IOException e) {
+			throw new EmailException(format(ERROR_RESOLVING_IMAGE_DATASOURCE, srcLocation));
+		}
+	}
+
 	/**
 	 * @see EmailPopulatingBuilder#fixingMessageId(String)
 	 */