feat: Add flag verification function

src/solvertools/flags.py

@@ -1,13 +1,46 @@
 from pwn import log
 import re
 import sys
+import os
+import yaml
+
+
+def verify_flag(data, regex):
+    """
+    Verify the flag using challenge.yml if available. 
+    Otherwise, use regex-based verification.
+    """
+    flag = extract_flag(data, regex)
+    challenge_file = "challenge.yml"
+
+    if not os.path.exists(challenge_file):
+        # No challenge.yml, skip verification
+        log.warning("Missing challenge.yml, skipping verification.")
+        return
+
+    # challenge.yml exists, load and check against listed flags
+    try:
+        with open(challenge_file, 'r') as f:
+            data = yaml.safe_load(f)
+    except Exception as e:
+        log.failure(f"Error reading challenge.yml: {e}")
+        sys.exit(1)
+
+    flags = data.get("flags", [])
+
+    if flag in flags:
+        log.success("Flag verified successfully.")
+        sys.exit(0)
+    else:
+        log.failure("Flag not present in challenge.yml.")
+        sys.exit(2)
 
 
 def extract_flag(data, regex):
     match = re.findall(regex, data)
     if match:
         log.success(f"Flag found: {match[0]}")
-        sys.exit(0)
+        return match[0]
     else:
         log.failure("Flag not found.")
         sys.exit(1)