#202: fixed concurrent modification exception when moving invalid embedded images to regular attachments list (big thanks to @nedashley!)

Author: bbottema

src/main/java/org/simplejavamail/converter/internal/mimemessage/MimeMessageParser.java

@@ -29,6 +29,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
@@ -447,20 +448,21 @@ public static String parseMessageId(@Nonnull final MimeMessage mimeMessage) {
 		}
 	}
 
-	private static void moveInvalidEmbeddedResourcesToAttachments(ParsedMimeMessageComponents parsedComponents) {
+	static void moveInvalidEmbeddedResourcesToAttachments(ParsedMimeMessageComponents parsedComponents) {
 		final String htmlContent = parsedComponents.htmlContent;
-		for (Map.Entry<String, DataSource> cidEntry : parsedComponents.cidMap.entrySet()) {
+		for(Iterator<Map.Entry<String, DataSource>> it = parsedComponents.cidMap.entrySet().iterator(); it.hasNext(); ) {
+			Map.Entry<String, DataSource> cidEntry = it.next();
 			String cid = extractCID(cidEntry.getKey());
 			if (htmlContent == null || !htmlContent.contains("cid:" + cid)) {
 				parsedComponents.attachmentList.put(cid, cidEntry.getValue());
-				parsedComponents.cidMap.remove(cidEntry.getKey());
+				it.remove();
 			}
 		}
 	}
 
 	public static class ParsedMimeMessageComponents {
-		private final Map<String, DataSource> attachmentList = new TreeMap<>();
-		private final Map<String, DataSource> cidMap = new TreeMap<>();
+		final Map<String, DataSource> attachmentList = new TreeMap<>();
+		final Map<String, DataSource> cidMap = new TreeMap<>();
 		private final Map<String, Object> headers = new HashMap<>();
 		private final List<InternetAddress> toAddresses = new ArrayList<>();
 		private final List<InternetAddress> ccAddresses = new ArrayList<>();
@@ -473,7 +475,7 @@ public static class ParsedMimeMessageComponents {
 		private InternetAddress returnReceiptTo;
 		private InternetAddress bounceToAddress;
 		private String plainContent;
-		private String htmlContent;
+		String htmlContent;
 
 		public String getMessageId() {
 			return messageId;

src/test/java/org/simplejavamail/converter/internal/mimemessage/MimeMessageParserTest.java

@@ -0,0 +1,46 @@
+package org.simplejavamail.converter.internal.mimemessage;
+
+import org.junit.Test;
+import org.simplejavamail.converter.internal.mimemessage.MimeMessageParser.ParsedMimeMessageComponents;
+
+import javax.mail.util.ByteArrayDataSource;
+import java.io.IOException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.simplejavamail.converter.internal.mimemessage.MimeMessageParser.moveInvalidEmbeddedResourcesToAttachments;
+
+public class MimeMessageParserTest {
+	@Test
+	public void testMoveInvalidEmbeddedResourcesToAttachments_NoHtmlNoInvalid() throws IOException {
+		ParsedMimeMessageComponents parsedComponents = new ParsedMimeMessageComponents();
+		parsedComponents.cidMap.put("moo1", new ByteArrayDataSource("moomoo", "text/plain"));
+		parsedComponents.cidMap.put("moo2", new ByteArrayDataSource("moomoo", "text/plain"));
+		moveInvalidEmbeddedResourcesToAttachments(parsedComponents);
+		
+		assertThat(parsedComponents.cidMap).isEmpty();
+		assertThat(parsedComponents.attachmentList).containsOnlyKeys("moo1","moo2");
+	}
+	@Test
+	public void testMoveInvalidEmbeddedResourcesToAttachments_HtmlButNoInvalid() throws IOException {
+		ParsedMimeMessageComponents parsedComponents = new ParsedMimeMessageComponents();
+		parsedComponents.htmlContent = "blah moo1 blah html";
+		parsedComponents.cidMap.put("moo1", new ByteArrayDataSource("moomoo", "text/plain"));
+		parsedComponents.cidMap.put("moo2", new ByteArrayDataSource("moomoo", "text/plain"));
+		moveInvalidEmbeddedResourcesToAttachments(parsedComponents);
+		
+		assertThat(parsedComponents.cidMap).isEmpty();
+		assertThat(parsedComponents.attachmentList).containsOnlyKeys("moo1","moo2");
+	}
+	
+	@Test
+	public void testMoveInvalidEmbeddedResourcesToAttachments_Invalid() throws IOException {
+		ParsedMimeMessageComponents parsedComponents = new ParsedMimeMessageComponents();
+		parsedComponents.htmlContent = "blah cid:moo1 blah html";
+		parsedComponents.cidMap.put("moo1", new ByteArrayDataSource("moomoo", "text/plain"));
+		parsedComponents.cidMap.put("moo2", new ByteArrayDataSource("moomoo", "text/plain"));
+		moveInvalidEmbeddedResourcesToAttachments(parsedComponents);
+		
+		assertThat(parsedComponents.cidMap).containsOnlyKeys("moo1");
+		assertThat(parsedComponents.attachmentList).containsOnlyKeys("moo2");
+	}
+}