add sha256 validation

apt-sync.py

@@ -99,6 +99,51 @@ def mkdir_with_dot_tmp(folder: Path)->Tuple[Path, Path]:
     tmpdir.mkdir(parents=True, exist_ok=True)
     return (folder, tmpdir)
     
+def parse_packages_info(content: str, package_info = None, is_new = True):
+    
+    if package_info is None:
+        package_info = {}
+    
+    for pkg in content.split('\n\n'):
+        if len(pkg) < 10: # ignore blanks
+            continue
+        try:
+            pkg_filename = pattern_package_name.search(pkg).group(1)
+            pkg_size = int(pattern_package_size.search(pkg).group(1))
+            pkg_checksum = pattern_package_sha256.search(pkg).group(1)
+            if pkg_filename not in package_info:
+                if is_new:
+                    pkg_info = {
+                        'size': pkg_size,
+                        'sha256': {
+                            'new': pkg_checksum,
+                            'old': None
+                        }
+                    }
+                else:
+                    pkg_info = {
+                        'size': None,
+                        'sha256': {
+                            'new': None,
+                            'old': pkg_checksum
+                        }
+                    }
+            else:
+                pkg_info = package_info[pkg_filename]
+                if is_new:
+                    pkg_info['size'] = pkg_size
+                    pkg_info['sha256']['new'] = pkg_checksum
+                else:
+                    pkg_info['sha256']['old'] = pkg_checksum
+            package_info.update({
+                pkg_filename: pkg_info
+            })
+        except:
+            print("Failed to parse one package description", flush=True)
+            traceback.print_exc()
+            return package_info
+    return package_info
+
 def move_files_in(src: Path, dst: Path):
     empty = True
     for file in src.glob('*'):
@@ -110,6 +155,9 @@ def move_files_in(src: Path, dst: Path):
         print(f"{src} is empty")
 
 def apt_mirror(base_url: str, dist: str, repo: str, arch: str, dest_base_dir: Path, deb_set: Dict[str, int])->int:
+    
+    package_info = {}
+    
     if not dest_base_dir.is_dir():
         print("Destination directory is empty, cannot continue")
         return 1
@@ -134,6 +182,7 @@ def apt_mirror(base_url: str, dist: str, repo: str, arch: str, dest_base_dir: Pa
     pkgidx_dir,pkgidx_tmp_dir = mkdir_with_dot_tmp(comp_dir / arch_dir)
     with open(release_file, "r") as fd:
         pkgidx_content=None
+        pkgidx_content_old = None
         cnt_start=False
         for line in fd:
             if cnt_start:
@@ -146,6 +195,8 @@ def apt_mirror(base_url: str, dist: str, repo: str, arch: str, dest_base_dir: Pa
                    filename.startswith(f"Contents-{arch}"):
                     fn = Path(filename)
                     pkgidx_file = dist_dir / fn.parent / ".tmp" / fn.name
+                    if pkgidx_file.stem == 'Packages':
+                        pkgidx_file_old = Path(f'{dist_dir}/{filename}')
                 else:
                     print(f"Ignore the file {filename}")
                     continue
@@ -176,12 +227,38 @@ def apt_mirror(base_url: str, dist: str, repo: str, arch: str, dest_base_dir: Pa
                         pkgidx_content = content.decode('utf-8')
                     else:
                         print("unsupported format")
+                        continue
+                    
+                    package_info = parse_packages_info(pkgidx_content, package_info = package_info, is_new = True)
+                    
+                if not os.path.exists(pkgidx_file_old):
+                    continue
+                
+                with pkgidx_file_old.open('rb') as t: content = t.read()
+                if pkgidx_content_old is None and pkgidx_file_old.stem == 'Packages':
+                    print(f"getting packages index content from old {pkgidx_file_old.name}", flush=True)
+                    suffix = pkgidx_file.suffix
+                    if suffix == '.xz':
+                        pkgidx_content_old = lzma.decompress(content).decode('utf-8')
+                    elif suffix == '.bz2':
+                        pkgidx_content_old = bz2.decompress(content).decode('utf-8')
+                    elif suffix == '.gz':
+                        pkgidx_content_old = gzip.decompress(content).decode('utf-8')
+                    elif suffix == '':
+                        pkgidx_content_old = content.decode('utf-8')
+                    else:
+                        print("unsupported format")
+                        continue
+                    
+                    package_info = parse_packages_info(pkgidx_content_old, package_info = package_info, is_new = False)
+                    
 
             # Currently only support SHA-256 checksum, because
             # "Clients may not use the MD5Sum and SHA1 fields for security purposes, and must require a SHA256 or a SHA512 field."
             # from https://wiki.debian.org/DebianRepository/Format#A.22Release.22_files
             if line.startswith('SHA256:'):
                 cnt_start = True
+    
     if not cnt_start:
         print("Cannot find SHA-256 checksum")
         return 1
@@ -216,18 +293,13 @@ def apt_mirror(base_url: str, dist: str, repo: str, arch: str, dest_base_dir: Pa
     err = 0
     deb_count = 0
     deb_size = 0
-    for pkg in pkgidx_content.split('\n\n'):
+    for pkg_filename, pkg_info in package_info.items():
-        if len(pkg) < 10: # ignore blanks
+        pkg_size = pkg_info['size']
-            continue
+        pkg_checksum = pkg_info['sha256']
-        try:
+        
-            pkg_filename = pattern_package_name.search(pkg).group(1)
+        if pkg_checksum['new'] is None and pkg_size is None:
-            pkg_size = int(pattern_package_size.search(pkg).group(1))
-            pkg_checksum = pattern_package_sha256.search(pkg).group(1)
-        except:
-            print("Failed to parse one package description", flush=True)
-            traceback.print_exc()
-            err = 1
             continue
+        
         deb_count += 1
         deb_size += pkg_size
 
@@ -237,8 +309,8 @@ def apt_mirror(base_url: str, dist: str, repo: str, arch: str, dest_base_dir: Pa
             dest_dir.mkdir(parents=True, exist_ok=True)
         if dest_filename.suffix == '.deb':
             deb_set[str(dest_filename.relative_to(dest_base_dir))] = pkg_size
-        if dest_filename.is_file() and dest_filename.stat().st_size == pkg_size:
+        if dest_filename.is_file() and dest_filename.stat().st_size == pkg_size and pkg_checksum['old'] == pkg_checksum['new']:
-            print(f"Skipping {pkg_filename}, size {pkg_size}")
+            print(f"Skipping {pkg_filename}, size {pkg_size}, sha256 {pkg_checksum['new']}")
             continue
 
         pkg_url=f"{base_url}/{pkg_filename}"
@@ -253,8 +325,8 @@ def apt_mirror(base_url: str, dist: str, repo: str, arch: str, dest_base_dir: Pa
             with dest_tmp_filename.open("rb") as f:
                 for block in iter(lambda: f.read(1024**2), b""):
                     sha.update(block)
-            if sha.hexdigest() != pkg_checksum:
+            if sha.hexdigest() != pkg_checksum['new']:
-                print(f"Invalid checksum of {dest_filename}, expected {pkg_checksum}")
+                print(f"Invalid checksum of {dest_filename}, expected {pkg_checksum['new']}")
                 dest_tmp_filename.unlink()
                 continue
             dest_tmp_filename.rename(dest_filename)