feat(moderation): fetch and analyze URLs (images and web text) from messages

- Added to safely extract and fetch up to 3 URLs per message (with SSRF protection, 5MB limit, and 8s timeout). - Implemented recursive extraction to resolve Tenor/Giphy links from their HTML viewers to raw GIF binaries. - In , fetched images are automatically injected as into the vision LLM context, and truncated webpage text is appended to the message string.
2026-05-28 01:29:31 +07:00
parent c6af313c33
commit 441ff5a0ed
2 changed files with 259 additions and 2 deletions
@@ -9,6 +9,7 @@ import type {
  AttachmentRecord,
  MessageRecord,
 } from "./types.js";
+import { extractUrlsFromText, fetchUrlSafely } from "./urlFetcher.js";

 const ModerationResponseSchema = z.object({
  results: z.array(
@@ -468,6 +469,49 @@ export async function runModerationAnalysis(
    }),
  );

+  // --- Fetch URLs found in target messages ---
+  // To avoid slowing down the pipeline too much, we limit to 3 URLs per message.
+  const messageWebTextMap = new Map<string, string[]>();
+
+  await Promise.all(
+    targets.map(async (msg) => {
+      const content = msg.edited_content ?? msg.content;
+      const urls = extractUrlsFromText(content).slice(0, 3);
+      if (urls.length === 0) return;
+
+      const webTexts: string[] = [];
+
+      await Promise.all(
+        urls.map(async (url) => {
+          const result = await fetchUrlSafely(url);
+
+          if (result.type === "image" && result.data && result.mimeType) {
+            // Append as an image part
+            const dataUrl = `data:${result.mimeType};base64,${result.data.toString("base64")}`;
+            const part: RawImagePart = {
+              type: "image_url",
+              image_url: { url: dataUrl },
+            };
+            const existing = messageImageMap.get(msg.id) ?? [];
+            existing.push(part);
+            messageImageMap.set(msg.id, existing);
+          } else if (result.type === "text" && result.textContent) {
+            webTexts.push(`[Isi Web dari ${url}]: ${result.textContent}`);
+          } else if (result.type === "error") {
+            log.debug(
+              { url, error: result.error },
+              "Failed to fetch URL for moderation context",
+            );
+          }
+        }),
+      );
+
+      if (webTexts.length > 0) {
+        messageWebTextMap.set(msg.id, webTexts);
+      }
+    }),
+  );
+
  const hasImages = messageImageMap.size > 0;

  // -------------------------------------------------------------------------
@@ -571,7 +615,10 @@ CRITICAL: "message_id" HARUS berupa STRING (dibungkus tanda kutip ganda). Jangan
      const messagesBlock = targets
        .map((msg) => {
          const content = msg.edited_content ?? msg.content;
-          return `[target] id=${msg.id} user=${msg.username}: ${content}`;
+          const webTexts = messageWebTextMap.get(msg.id) ?? [];
+          const webContext =
+            webTexts.length > 0 ? `\n${webTexts.join("\n")}` : "";
+          return `[target] id=${msg.id} user=${msg.username}: ${content}${webContext}`;
        })
        .join("\n");

@@ -588,7 +635,10 @@ CRITICAL: "message_id" HARUS berupa STRING (dibungkus tanda kutip ganda). Jangan

    for (const msg of targets) {
      const content = msg.edited_content ?? msg.content;
-      const msgText = `[target] id=${msg.id} user=${msg.username}: ${content}`;
+      const webTexts = messageWebTextMap.get(msg.id) ?? [];
+      const webContext = webTexts.length > 0 ? `\n${webTexts.join("\n")}` : "";
+
+      const msgText = `[target] id=${msg.id} user=${msg.username}: ${content}${webContext}`;
      parts.push({ type: "text", text: msgText });

      // Immediately follow the message text with its images
@@ -0,0 +1,207 @@
+import { resolve } from "node:dns/promises";
+import { isIP } from "node:net";
+import { createChildLogger } from "../logger.js";
+
+const log = createChildLogger("urlFetcher");
+
+export interface FetchedUrlContext {
+  url: string;
+  type: "image" | "text" | "error";
+  data?: Buffer;
+  mimeType?: string;
+  textContent?: string;
+  error?: string;
+}
+
+const MAX_FETCH_SIZE = 5 * 1024 * 1024; // 5 MB
+const FETCH_TIMEOUT_MS = 8000;
+const URL_REGEX = /https?:\/\/[^\s<]+[^<.,:;"')\]\s]/gi;
+
+/**
+ * Basic SSRF protection.
+ * Note: A sophisticated attacker could still use DNS rebinding.
+ */
+async function isSafeUrl(urlStr: string): Promise<boolean> {
+  try {
+    const parsed = new URL(urlStr);
+    const host = parsed.hostname;
+
+    // Block obvious local IPs/hostnames
+    if (
+      host === "localhost" ||
+      host === "127.0.0.1" ||
+      host === "::1" ||
+      host.startsWith("192.168.") ||
+      host.startsWith("10.") ||
+      /^172\.(1[6-9]|2[0-9]|3[0-1])\./.test(host)
+    ) {
+      return false;
+    }
+
+    // Try resolving to check if it resolves to a local IP
+    if (!isIP(host)) {
+      try {
+        const addresses = await resolve(host);
+        for (const ip of addresses) {
+          if (
+            ip === "127.0.0.1" ||
+            ip.startsWith("192.168.") ||
+            ip.startsWith("10.") ||
+            /^172\.(1[6-9]|2[0-9]|3[0-1])\./.test(ip)
+          ) {
+            return false;
+          }
+        }
+      } catch (err) {
+        // If DNS fails, we can't fetch it anyway
+        return false;
+      }
+    }
+
+    return true;
+  } catch (err) {
+    return false;
+  }
+}
+
+function extractOgImage(html: string): string | null {
+  // Look for <meta ... property="og:image" ... content="..."> or <meta ... name="twitter:image" ... content="...">
+  const ogRegex = /<meta[^>]*(?:property|name)=["'](?:og:image|twitter:image)["'][^>]*content=["']([^"']+)["']/i;
+  const match = html.match(ogRegex);
+  if (match && match[1]) {
+    // Unescape basic HTML entities
+    return match[1].replace(/&amp;/g, "&").replace(/&quot;/g, '"');
+  }
+
+  // Try reversed attribute order: <meta ... content="..." ... property="og:image">
+  const ogRegexRev = /<meta[^>]*content=["']([^"']+)["'][^>]*(?:property|name)=["'](?:og:image|twitter:image)["']/i;
+  const matchRev = html.match(ogRegexRev);
+  if (matchRev && matchRev[1]) {
+    return matchRev[1].replace(/&amp;/g, "&").replace(/&quot;/g, '"');
+  }
+
+  return null;
+}
+
+function truncateAndCleanHtml(html: string, maxLen = 1000): string {
+  // Strip <script> and <style> entirely
+  let text = html.replace(
+    /<script\b[^<]*(?:(?!<\/script>)<[^<]*)*<\/script>/gi,
+    " ",
+  );
+  text = text.replace(/<style\b[^<]*(?:(?!<\/style>)<[^<]*)*<\/style>/gi, " ");
+  // Strip all other HTML tags
+  text = text.replace(/<[^>]+>/g, " ");
+  // Replace multiple spaces/newlines
+  text = text.replace(/\s+/g, " ").trim();
+
+  return text.substring(0, maxLen);
+}
+
+export async function fetchUrlSafely(
+  url: string,
+  depth = 0,
+): Promise<FetchedUrlContext> {
+  if (depth > 1) {
+    return { url, type: "error", error: "Max redirect/meta depth reached" };
+  }
+
+  if (!(await isSafeUrl(url))) {
+    return { url, type: "error", error: "Unsafe URL blocked" };
+  }
+
+  const controller = new AbortController();
+  const timeoutId = setTimeout(() => controller.abort(), FETCH_TIMEOUT_MS);
+
+  try {
+    const response = await fetch(url, {
+      signal: controller.signal,
+      headers: {
+        "User-Agent":
+          "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 DiscordBot/2.0",
+        Accept: "image/webp,image/apng,image/*,*/*;q=0.8",
+      },
+      // Do not follow more than a few redirects natively, fetch handles up to 20 by default
+    });
+
+    if (!response.ok) {
+      return { url, type: "error", error: `HTTP ${response.status}` };
+    }
+
+    const contentType = response.headers.get("content-type") || "";
+    const contentLength = parseInt(
+      response.headers.get("content-length") || "0",
+      10,
+    );
+
+    if (contentLength > MAX_FETCH_SIZE) {
+      return { url, type: "error", error: "Content too large" };
+    }
+
+    const buffer = await response.arrayBuffer();
+    if (buffer.byteLength > MAX_FETCH_SIZE) {
+      return { url, type: "error", error: "Downloaded content too large" };
+    }
+
+    if (contentType.startsWith("image/")) {
+      return {
+        url,
+        type: "image",
+        data: Buffer.from(buffer),
+        mimeType: contentType,
+      };
+    }
+
+    if (
+      contentType.startsWith("text/html") ||
+      contentType.startsWith("text/plain")
+    ) {
+      const text = Buffer.from(buffer).toString("utf-8");
+
+      // If it's HTML, try to find an og:image first (for Tenor/Giphy etc)
+      if (contentType.startsWith("text/html")) {
+        const ogImage = extractOgImage(text);
+        if (ogImage && ogImage.startsWith("http")) {
+          // Fetch the og:image instead
+          return fetchUrlSafely(ogImage, depth + 1);
+        }
+      }
+
+      // Fallback to text content
+      const cleaned = truncateAndCleanHtml(text, 1000);
+      return {
+        url,
+        type: "text",
+        textContent: cleaned,
+      };
+    }
+
+    return {
+      url,
+      type: "error",
+      error: `Unsupported content type: ${contentType}`,
+    };
+  } catch (err) {
+    return {
+      url,
+      type: "error",
+      error: err instanceof Error ? err.message : String(err),
+    };
+  } finally {
+    clearTimeout(timeoutId);
+  }
+}
+
+export function extractUrlsFromText(text: string): string[] {
+  const matches = text.match(URL_REGEX);
+  if (!matches) return [];
+  // Deduplicate and filter out things that obviously aren't valid
+  return Array.from(new Set(matches)).filter((url) => {
+    try {
+      new URL(url);
+      return true;
+    } catch {
+      return false;
+    }
+  });
+}