added structural check

SOLUTION.md

@@ -1,6 +1,10 @@
 # Design Approach
 
-Describe the approach you took to design your block construction program, explain all the key concepts of creating a valid block.
+## Check Structure of Transactions
+
+First of all we need to check the structure of the transaction which includes version, locktime, inputs and outputs.
+
+
 
 
 

main.py

@@ -0,0 +1,4 @@
+from .python_files import structural_check
+
+# Run the structural check on the transactions in the mempool
+structural_check.check_structure_transactions("./mempool")

python_files/structural_check.py

@@ -0,0 +1,156 @@
+import json
+import os
+
+
+def check_transaction(tx_data):
+
+    required_fields = ["version", "locktime", "vin", "vout"]
+    if not all(field in tx_data for field in required_fields):
+        return False  # Missing fields
+
+    # Basic checks for specific field types
+    if not isinstance(tx_data["version"], int):
+        return False
+    if not isinstance(tx_data["locktime"], int):
+        return False
+
+    # Call the vin and vout checker functions
+    if not validate_vin(tx_data["vin"]):
+        return False
+    if not validate_vout(tx_data["vout"]):
+        return False
+
+    return True  # Passes basic checks
+
+
+def validate_vin(vin):
+    # Validates a single vin element with specific checks
+
+    # Check txid
+    if not vin.get("txid") or not isinstance(vin["txid"], str):
+        return False, "txid is empty or invalid type"
+
+    # Check vout
+    if not vin.get("vout") or not isinstance(vin["vout"], int):
+        return False, "vout is empty or invalid type"
+
+    # Check prevout
+    prevout = vin.get("prevout")
+    if not prevout:
+        return False, "prevout is missing"
+    required_prevout_fields = [
+        "scriptpubkey",
+        "scriptpubkey_asm",
+        "scriptpubkey_type",
+        "scriptpubkey_address",
+        "value",
+    ]
+    for field in required_prevout_fields:
+        if field not in prevout:
+            return False, f"prevout is missing '{field}'"
+
+    # Check scriptsig/scriptsig_asm and witness if applicable
+    scriptsig = vin.get("scriptsig")
+    scriptsig_asm = vin.get("scriptsig_asm")
+
+    if not scriptsig and not scriptsig_asm:
+        # Both empty, check for witness
+        if not vin.get("witness"):
+            return (
+                False,
+                "Both scriptsig and scriptsig_asm are empty, and witness is missing",
+            )  # (If both scriptsig and scriptsig_asm have data, we ignore witness)
+
+    # Check is_coinbase
+    if not isinstance(vin.get("is_coinbase"), bool):
+        return False  # is_coinbase must be true or false
+
+    # Check sequence
+    if not vin.get("sequence") or not isinstance(vin["sequence"], int):
+        return False  # sequence is empty or invalid type
+
+    # All checks passed
+    return True
+
+
+def validate_vout(vout):
+    # Validates a single vout element with specific checks
+
+    # Check non-emptiness of fields
+    required_fields = [
+        "scriptpubkey",
+        "scriptpubkey_asm",
+        "scriptpubkey_type",
+        "scriptpubkey_address",
+    ]
+    for field in required_fields:
+        if not vout.get(field) or not isinstance(vout[field], str):
+            return False, f"'{field}' is empty or invalid type"
+
+    # Check value is non-empty integer
+    if not vout.get("value") or not isinstance(vout["value"], int):
+        return False, "value is empty or invalid type"
+
+    # All checks passed
+    return True, "vout is valid"
+
+
+def check_structure_transactions(mempool_folder):
+
+    for filename in os.listdir(mempool_folder):
+        if filename.endswith(".json"):
+            filepath = os.path.join(mempool_folder, filename)
+            try:
+                with open(filepath) as f:
+                    tx_data = json.load(f)
+                if check_transaction(tx_data):
+                    print(f"Transaction: {filename} - Valid Structure")
+                else:
+                    print(f"Transaction: {filename} - Missing or Invalid Fields")
+            except (FileNotFoundError, json.JSONDecodeError) as e:
+                print(f"Error processing {filename}: {e}")
+
+
+# validate the signature script
+def validate_signature_script(script):
+    """Validates a Bitcoin signature script.
+
+    Args:
+      script: The signature script to validate.
+
+    Returns:
+      True if the signature script is valid, False otherwise.
+    """
+
+    # Check if the script is empty.
+    if not script:
+        return False
+
+    # Check if the script is a valid push data script.
+    if script[0] >= 0x01 and script[0] <= 0x4B:
+        return True
+
+    # Check if the script is a valid opcode.
+    if script[0] in OP_CODES:
+        return True
+
+    # Check if the script is a valid combination of push data and opcodes.
+    for i in range(len(script)):
+        if script[i] >= 0x01 and script[i] <= 0x4B:
+            continue
+
+        if script[i] not in OP_CODES:
+            return False
+
+    # The script is valid.
+    return True
+
+
+# Example usage:
+
+script = "OP_DUP OP_HASH160 0x1234567890abcdef1234567890abcdef12345678 OP_EQUALVERIFY OP_CHECKSIG"
+
+if validate_signature_script(script):
+    print("The signature script is valid.")
+else:
+    print("The signature script is invalid.")