Improve IBAN validation

restalker/restalker.py

@@ -51,41 +51,89 @@ class Keyword(Item):
 
 
 class IBAN_Address(Item):
+    # IBAN length by country code (ISO 13616)
+    IBAN_LENGTH = {
+        "AD": 24, "AE": 23, "AT": 20, "AZ": 28, "BA": 20, "BE": 16,
+        "BG": 22, "BH": 22, "BR": 29, "CH": 21, "CR": 22, "CY": 28,
+        "CZ": 24, "DE": 22, "DK": 18, "DO": 28, "EE": 20, "ES": 24,
+        "FI": 18, "FO": 18, "FR": 27, "GB": 22, "GI": 23, "GL": 18,
+        "GR": 27, "GT": 28, "HR": 21, "HU": 28, "IE": 22, "IL": 23,
+        "IS": 26, "IT": 27, "JO": 30, "KW": 30, "KZ": 20, "LB": 28,
+        "LI": 21, "LT": 20, "LU": 20, "LV": 21, "MC": 27, "MD": 24,
+        "ME": 22, "MK": 19, "MR": 27, "MT": 31, "MU": 30, "NL": 18,
+        "NO": 15, "PK": 24, "PL": 28, "PS": 29, "PT": 25, "QA": 29,
+        "RO": 24, "RS": 22, "SA": 24, "SE": 24, "SI": 19, "SK": 24,
+        "SM": 27, "TN": 24, "TR": 26, "AL": 28, "BY": 28, "DJ": 27,
+        "EG": 29, "GE": 22, "IQ": 23, "LC": 32, "SC": 31, "ST": 25,
+        "SV": 28, "TL": 23, "UA": 29, "VA": 22, "VG": 24, "XK": 20,
+        "BI": 27, "FK": 18, "LY": 25, "MN": 20, "NI": 28, "RV": 33,
+        "SD": 18, "SO": 23
+    }
+
+    # Character to number conversion for IBAN validation
+    CHAR_CONVERSION = {
+        "A": 10, "B": 11, "C": 12, "D": 13, "E": 14, "F": 15, "G": 16,
+        "H": 17, "I": 18, "J": 19, "K": 20, "L": 21, "M": 22, "N": 23,
+        "O": 24, "P": 25, "Q": 26, "R": 27, "S": 28, "T": 29, "U": 30,
+        "V": 31, "W": 32, "X": 33, "Y": 34, "Z": 35
+    }
+
     @staticmethod
     def isvalid(address: str) -> bool:
-        ret = False
+        """Return true if the input string is a valid IBAN
+
+        An IBAN comprises of 15-32 alphanumeric characters with format:
+          - 2 characters for country code
+          - 2 control characters (checksum)
+          - up to 28 account characters depending on country
+
+        Validator checks length for country and IBAN checksum (ISO 13616)
+        """
         try:
             if not address:
                 return False
 
-            iban = address.replace(" ", "").upper()
+            # Normalize: strip, uppercase, remove spaces and hyphens
+            iban = address.strip().upper()
+            iban = iban.replace(" ", "").replace("-", "")
 
-            # Minimum length is from Norway with 15 chars
-            if len(iban) < 15:
+            # Must have at least 4 characters (country code + checksum)
+            if len(iban) < 4:
                 return False
 
-            # First 2 must be country code, then 2 numbers
+            # First 2 must be country code, then 2 digits for checksum
             if not (iban[:2].isalpha() and iban[2:4].isdigit()):
                 return False
 
-            # Checksum ISO-13616
-            rearranged = iban[4:] + iban[:4]
-
-            numeric = ""
-            for ch in rearranged:
-                if ch.isdigit():
-                    numeric += ch
-                elif ch.isalpha():
-                    numeric += str(ord(ch) - 55)  # A=10, B=11, ...
+            # Check length matches expected length for country
+            country_code = iban[:2]
+            expected_length = IBAN_Address.IBAN_LENGTH.get(country_code, None)
+            if expected_length is None:
+                return False  # Unknown country code
+
+            if len(iban) != expected_length:
+                return False  # Wrong length for this country
+
+            # Build checksum string: account + country code + check digits
+            check_str = ""
+            for char in iban[4:]:
+                if char.isdigit():
+                    check_str += char
+                elif char.isalpha():
+                    check_str += str(IBAN_Address.CHAR_CONVERSION.get(char, 0))
                 else:
-                    return False  # Invalid Character
+                    return False  # Invalid character
+
+            # Append converted country code and check digits
+            check_str += str(IBAN_Address.CHAR_CONVERSION.get(iban[0], 0))
+            check_str += str(IBAN_Address.CHAR_CONVERSION.get(iban[1], 0))
+            check_str += iban[2:4]
 
-            # IBAN if valid if mod 97 == 1
-            ret = int(numeric) % 97 == 1
+            # IBAN is valid if mod 97 equals 1 (ISO 13616 checksum)
+            return (int(check_str) % 97) == 1
+
         except Exception:
-            ret = False
-
-        return ret
+            return False
 
 
 class BTC_Wallet(Item):