Add automatic hash detection function

Author: ddalu5

.github/workflows/python-package.yml

@@ -32,3 +32,6 @@ jobs:
       run: |
         black --check .
 
+    - name: Unit tests
+      run: |
+        pytest .

pyntegrity/config.py

@@ -1,6 +1,29 @@
+"""
+Pyntegrity is Python package that helps checking a file integrity.
+Copyright (C) 2022  Salah OSFOR
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+"""
 # Hash settings
 
 SHA256_LENGTH = 64
 MD5_LENGTH = 32
 
-SUPPORTED_HASH_ALGOS = {"SHA256": SHA256_LENGTH, "MD5": MD5_LENGTH}
+SHA256_REX = rf"^[A-Fa-f0-9]{SHA256_LENGTH}$"
+MD5_REX = rf"^[a-fA-F\d]{MD5_LENGTH}$"
+
+SUPPORTED_HASH_ALGOS = {
+    "sha256": {"REX": SHA256_REX, "LENGTH": SHA256_LENGTH},
+    "md5": {"REX": MD5_REX, "LENGTH": MD5_LENGTH},
+}

pyntegrity/core.py

@@ -0,0 +1,40 @@
+"""
+Pyntegrity is Python package that helps checking a file integrity.
+Copyright (C) 2022  Salah OSFOR
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+"""
+from .exceptions import HashStrNotValidException
+from .exceptions import HashAlgorithmNotSupportedException
+
+from .config import SUPPORTED_HASH_ALGOS
+
+
+def detect_hash_algo(hash_str: str):
+    """
+    Detects hash algorithm based on its length.
+
+    :param hash_str: the hash string
+    :return: the name of the hash algorithm
+    :raises HashAlgorithmNotSupportedException: raised if the hash
+        length isn't valid for any supported algorithm
+    """
+    hash_len = len(hash_str)
+    for name, infos in SUPPORTED_HASH_ALGOS.items():
+        if infos["LENGTH"] == hash_len:
+            return name
+    else:
+        raise HashAlgorithmNotSupportedException(
+            detected_length=hash_len, hash_str=hash_str
+        )

pyntegrity/exceptions.py

@@ -33,7 +33,8 @@ def __init__(self, detected_length: int, hash_str: str):
             "[!] The hash string length does not "
             "match any supported hash algorithm: ["
         )
-        for hash_name, length in SUPPORTED_HASH_ALGOS.items():
+        for hash_name, infos in SUPPORTED_HASH_ALGOS.items():
+            length = infos["LENGTH"]
             self.message += f" {hash_name}: {length} chars, "
         self.message += "]"
 

requirements.txt

@@ -1 +1,2 @@
 black~=22.1
+pytest~=7.0

tests/test_core.py

@@ -0,0 +1,18 @@
+from unittest import TestCase
+from pyntegrity.core import detect_hash_algo
+from pyntegrity.exceptions import HashAlgorithmNotSupportedException
+
+
+class TestDetectHashAlgo(TestCase):
+    def test_detect_hash_algo_ok(self):
+        str32_len = "xzazyokqvhqzjbeyxpldfntsjiaumxan"
+        str64_len = "cmolcmtdtxffmfqnjgadqteqnnmacnhysxwpdanwtqzibkysmawoqxdiippzxpum"
+        hash_name = detect_hash_algo(str32_len)
+        self.assertEqual(hash_name, "md5")
+        hash_name = detect_hash_algo(str64_len)
+        self.assertEqual(hash_name, "sha256")
+
+    def test_detect_hash_algo_nok(self):
+        invalid_hash_str = "6545ed"
+        with self.assertRaises(HashAlgorithmNotSupportedException):
+            detect_hash_algo(invalid_hash_str)