E-Mail Anhänge gezielt per IMAP-Part laden

KI-AGENT: Der Anhang-Download lädt jetzt bevorzugt den passenden MIME-Part über die IMAP-BODYSTRUCTURE und bekommt ein Timeout, damit der Download nicht dauerhaft lädt.

backend/src/modules/email/email.sync.service.ts

@@ -49,6 +49,84 @@ const previewText = (text?: string | false | null) => {
     return text.replace(/\s+/g, " ").trim().slice(0, 240) || null
 }
 
+const attachmentFilename = (node: any) =>
+    node?.dispositionParameters?.filename
+    || node?.parameters?.name
+    || null
+
+const normalizeContentId = (value?: string | null) =>
+    value ? value.replace(/^<|>$/g, "") : null
+
+const collectAttachmentParts = (node: any, parts: any[] = []) => {
+    if (!node) return parts
+
+    if (node.part && !node.childNodes?.length) {
+        const filename = attachmentFilename(node)
+        const disposition = String(node.disposition || "").toLowerCase()
+
+        if (filename || node.id || ["attachment", "inline"].includes(disposition)) {
+            parts.push(node)
+        }
+    }
+
+    for (const child of node.childNodes || []) {
+        collectAttachmentParts(child, parts)
+    }
+
+    return parts
+}
+
+const findAttachmentPart = (bodyStructure: any, attachment: any) => {
+    const parts = collectAttachmentParts(bodyStructure)
+    if (!parts.length) return null
+
+    const scored = parts
+        .map((part) => {
+            let score = 0
+            if (attachmentFilename(part) && attachmentFilename(part) === attachment.filename) score += 4
+            if (part.type && part.type === attachment.contentType) score += 3
+            if (Number(part.size || 0) === Number(attachment.size || 0)) score += 2
+            if (
+                normalizeContentId(part.id)
+                && normalizeContentId(part.id) === normalizeContentId(attachment.contentId)
+            ) {
+                score += 3
+            }
+            return { part, score }
+        })
+        .sort((a, b) => b.score - a.score)
+
+    if (scored[0]?.score > 0) return scored[0].part
+    return parts.length === 1 ? parts[0] : null
+}
+
+const streamToBuffer = async (stream: any, timeoutMs = 45_000) => {
+    const chunks: Buffer[] = []
+    let timeout: NodeJS.Timeout | null = null
+
+    try {
+        await Promise.race([
+            (async () => {
+                for await (const chunk of stream) {
+                    chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk))
+                }
+            })(),
+            new Promise((_, reject) => {
+                timeout = setTimeout(() => {
+                    if (typeof stream.destroy === "function") {
+                        stream.destroy()
+                    }
+                    reject(new Error("Anhang-Download hat zu lange gedauert"))
+                }, timeoutMs)
+            }),
+        ])
+    } finally {
+        if (timeout) clearTimeout(timeout)
+    }
+
+    return Buffer.concat(chunks)
+}
+
 const flagsFromMessage = (flags: Set<string> | string[] | undefined) => {
     if (!flags) return []
     return Array.isArray(flags) ? flags : Array.from(flags)
@@ -645,34 +723,62 @@ export function emailSyncService(server: FastifyInstance) {
             try {
                 await client.mailboxOpen(row.message.mailboxPath)
 
-                for await (const fetched of client.fetch([row.message.uid], {
+                const structureMessage = await client.fetchOne(String(row.message.uid), {
-                    source: true,
+                    uid: true,
-                }, { uid: true })) {
+                    bodyStructure: true,
-                    if (!fetched.source) break
+                }, { uid: true })
+                const attachmentPart = structureMessage
+                    ? findAttachmentPart(structureMessage.bodyStructure, row.attachment)
+                    : null
 
-                    const parsed = await simpleParser(fetched.source)
+                if (attachmentPart?.part) {
-                    const matchedAttachment = parsed.attachments.find((item) =>
+                    const downloaded = await client.download(String(row.message.uid), attachmentPart.part, { uid: true })
-                        (row.attachment.checksum && item.checksum === row.attachment.checksum)
+                    const content = await streamToBuffer(downloaded.content)
-                        || (
-                            item.filename === row.attachment.filename
-                            && item.contentType === row.attachment.contentType
-                            && Number(item.size || 0) === Number(row.attachment.size || 0)
-                        )
-                    )
-                    const attachment = matchedAttachment
-                        || parsed.attachments[attachmentIndex]
-                        || (parsed.attachments.length === 1 ? parsed.attachments[0] : null)
 
-                    if (!attachment) break
+                    if (content.length) {
-
+                        return {
-                    return {
+                            filename: downloaded.meta?.filename
-                        filename: attachment.filename || row.attachment.filename || "anhang",
+                                || attachmentFilename(attachmentPart)
-                        contentType: attachment.contentType || row.attachment.contentType || "application/octet-stream",
+                                || row.attachment.filename
-                        content: Buffer.isBuffer(attachment.content)
+                                || "anhang",
-                            ? attachment.content
+                            contentType: downloaded.meta?.contentType
-                            : Buffer.from(attachment.content),
+                                || attachmentPart.type
+                                || row.attachment.contentType
+                                || "application/octet-stream",
+                            content,
+                        }
                     }
                 }
+
+                const fetched = await client.fetchOne(String(row.message.uid), {
+                    source: true,
+                }, { uid: true })
+                if (!fetched || !fetched.source) return null
+
+                const parsed = await simpleParser(fetched.source)
+                const matchedAttachment = parsed.attachments.find((item) =>
+                    (row.attachment.checksum && item.checksum === row.attachment.checksum)
+                    || (
+                        item.filename === row.attachment.filename
+                        && item.contentType === row.attachment.contentType
+                        && Number(item.size || 0) === Number(row.attachment.size || 0)
+                    )
+                )
+                const attachment = matchedAttachment
+                    || parsed.attachments[attachmentIndex]
+                    || (parsed.attachments.length === 1 ? parsed.attachments[0] : null)
+
+                if (!attachment) {
+                    return null
+                }
+
+                return {
+                    filename: attachment.filename || row.attachment.filename || "anhang",
+                    contentType: attachment.contentType || row.attachment.contentType || "application/octet-stream",
+                    content: Buffer.isBuffer(attachment.content)
+                        ? attachment.content
+                        : Buffer.from(attachment.content),
+                }
             } finally {
                 lock.release()
             }

frontend/pages/email/index.vue

@@ -458,6 +458,7 @@ async function downloadAttachment(attachment: NonNullable<EmailMessage["attachme
   try {
     const response = await $api.raw(`/api/email/attachments/${attachment.id}/download`, {
       responseType: "arrayBuffer",
+      timeout: 60_000,
     })
     const contentType = response.headers.get("content-type") || attachment.contentType || "application/octet-stream"
     const blob = new Blob([response._data as ArrayBuffer], { type: contentType })