cdn checker update view post

receiver/challenges/CDN.py

@@ -111,17 +111,14 @@ class CDN(Challenge):
         # [3/9] flag.txt MUST exist and MUST equal host copy
         self.logger.info("[3/9] Verifying /flag.txt exists and matches host copy ...")
         try:
-            # read container flag
             proc = self._docker_exec(["/bin/sh", "-lc", f"test -f {self.container_flag_path} && cat {self.container_flag_path}"])
             assert proc.returncode == 0, "flag.txt missing in container"
             container_flag = (proc.stdout or "").strip()
             assert container_flag, "flag.txt empty"
 
-            # read host copy
             with open(self.flag_location, "r", encoding="utf-8") as fh:
                 host_flag = fh.read().strip()
 
-            # exact match
             assert container_flag == host_flag, "flag.txt content changed/mismatch"
             self.logger.info("    ✓ flag.txt present and unchanged")
         except Exception as e:
@@ -169,26 +166,50 @@ class CDN(Challenge):
             self.logger.error(f"    ✗ Upload failed: {e}")
             return False
 
-        # [7/9] Find newest post id (prefer near our title)
-        self.logger.info("[7/9] Resolving new post id from /gallery ...")
+        # [7/9] Resolve post id from the JUST-CREATED post (not the newest in gallery)
+        self.logger.info("[7/9] Resolving post id from upload result ...")
         try:
-            r = s.get(base_url + "/gallery", timeout=10)
-            if r.status_code != 200:
-                r = s.get(base_url + "/", timeout=10)
-                assert r.status_code == 200, f"Index HTTP {r.status_code}"
+            created_post_id: Optional[int] = None
 
-            post_id: Optional[int] = None
-            for m in re.finditer(re.escape(title), r.text):
-                window = r.text[max(0, m.start()-1000): m.start()+1000]
-                mm = re.search(r'/post/(\d+)', window)
+            # Check redirect chain and final URL for /post/<id>
+            candidate_urls = []
+            if r.history:
+                for resp in r.history:
+                    loc = resp.headers.get("Location", "")
+                    if loc:
+                        candidate_urls.append(loc if loc.startswith("http") else base_url + loc)
+            candidate_urls.append(getattr(r, "url", ""))
+
+            for u in candidate_urls:
+                m = re.search(r'/post/(\d+)', u or "")
+                if m:
+                    created_post_id = int(m.group(1))
+                    break
+
+            # If still None, try to parse the response body for a /post/<id> link
+            if created_post_id is None:
+                mm = re.search(r'/post/(\d+)', r.text or "")
                 if mm:
-                    post_id = int(mm.group(1)); break
-            if post_id is None:
-                ids = re.findall(r'/post/(\d+)', r.text)
-                assert ids, "No /post/<id> links found"
-                post_id = max(map(int, ids))
+                    created_post_id = int(mm.group(1))
 
-            self.logger.info(f"    ✓ Post id = {post_id}")
+            # LAST RESORT: fallback to gallery by matching our unique title window (kept for robustness)
+            if created_post_id is None:
+                self.logger.info("    ↪ Falling back to /gallery title match ...")
+                gr = s.get(base_url + "/gallery", timeout=10)
+                if gr.status_code != 200:
+                    gr = s.get(base_url + "/", timeout=10)
+                    assert gr.status_code == 200, f"Index HTTP {gr.status_code}"
+
+                post_id: Optional[int] = None
+                for m in re.finditer(re.escape(title), gr.text):
+                    window = gr.text[max(0, m.start()-1000): m.start()+1000]
+                    mm2 = re.search(r'/post/(\d+)', window)
+                    if mm2:
+                        post_id = int(mm2.group(1)); break
+                assert post_id is not None, "Could not resolve created post id"
+                created_post_id = post_id
+
+            self.logger.info(f"    ✓ Post id = {created_post_id}")
         except Exception as e:
             self.logger.error(f"    ✗ Post discovery failed: {e}")
             return False
@@ -196,7 +217,7 @@ class CDN(Challenge):
         # [8/9] Post renders
         self.logger.info("[8/9] Verifying post page renders ...")
         try:
-            vp = s.get(base_url + f"/post/{post_id}", timeout=10)
+            vp = s.get(base_url + f"/post/{created_post_id}", timeout=10)
             assert vp.status_code == 200, f"Post HTTP {vp.status_code}"
             assert title in vp.text, "Post title missing"
             self.logger.info("    ✓ Post page OK")
@@ -207,13 +228,11 @@ class CDN(Challenge):
         # [9/9] Metadata must be real ExifTool output (no fallbacks)
         self.logger.info("[9/9] Verifying metadata via /post/<id> (ExifTool) ...")
         try:
-            mr = s.get(base_url + f"/post/{post_id}", timeout=10)
+            mr = s.get(base_url + f"/post/{created_post_id}", timeout=10)
             assert mr.status_code == 200, f"Meta HTTP {mr.status_code}"
             meta = (mr.text or "").strip()
             assert meta, "Empty metadata"
-            # refuse app fallbacks
             assert "no-metadata" not in meta and "exif_err:" not in meta, "App fallback metadata detected"
-            # must contain canonical ExifTool keys
             assert all(k in meta for k in self._exif_must_have), "Metadata is not ExifTool output"
             self.logger.info("    ✓ Metadata present and produced by ExifTool")
         except Exception as e: