Refracted code and added mirror feature

README.md

@@ -21,11 +21,11 @@ if you want to avoid use GitHub.
 - Verboses changes if requested
 - Can rewrite sources files if run as `root`
 - Does backup old sources files for easy restoring
+- Supports mirror lists for allowing fallback to direct connection (see [`man apt-transport-mirror`](https://manpages.debian.org/buster/apt/apt-transport-mirror.1.en.html))
 
 ### ToDo
 
 - Support https for approx
-- Implement '--mirror' mode
 
 ## Usage
 
@@ -51,7 +51,12 @@ If you want to approve these changes, run as `root`:
 ```
 
 Now your system will use the approx cache.
-The old entries are commented out.
+The old entries can be found in the backup files.
+
+### Mirror Mode
+
+To use mirror mode, follow the same approach as above,
+but append the flag `-m` or `--mirror-mode` to the arguments.
 
 ## Contribute
 

redirect.py

@@ -2,6 +2,8 @@
 
 # Imports
 import argparse
+from contextlib import contextmanager
+import hashlib
 import os
 from pathlib import Path
 import re
@@ -35,11 +37,12 @@ def verb(txt, add=0):
     if verbose_mode:
         print((" " * (verboseLevel * 4 + add)) + txt)
 
-def verbLevel(num):
+@contextmanager
+def verbLevelContext(mul=1):
     global verboseLevel
-    verboseLevel += num
+    verboseLevel += mul
-    if verboseLevel < 0:
+    yield None
-        verboseLevel = 0
+    verboseLevel -= mul
 
 def splitDomainPath(url):
     if "/" in url:
@@ -73,12 +76,14 @@ def url_to_regex(url, multi_mapping=multi_mapping):
         url = removeProtocol(url)
         domain, path = splitDomainPath(url)
         # Check if domain is given in multi_mapping
+        is_multi_mapped = False
         for m in multi_mapping:
             if m.match(domain):
                 # If given exchange with multi mapped regex
                 url_pattern = m.sub(m.pattern, domain) + re.escape(path)
+                is_multi_mapped = True
                 break
-        else:
+        if not is_multi_mapped:
             url_pattern = re.escape(url)
         # Prefix protocol again
         return r"https?://" + url_pattern
@@ -91,66 +96,83 @@ def modifyMap(d):
 def isDebLine(line):
     return lineReplaceRegex.search(line) is not None
 
-def checkFile(file, map):
+def checkFile(source_file, mapping):
+    global mirror_mode
+    global mirror_path
     global write_mode
-    verb(("Run replacements on" if write_mode else "Check") + f" {file}:")
+    verb(("Run replacements on" if write_mode else "Check") + f" {source_file}:")
-    verbLevel(1)
+    with verbLevelContext():
-    if write_mode:
+        origFilePath = Path(source_file)
-        newFile = tempfile.NamedTemporaryFile(mode="w", delete=False)
-    changed = False
-    for line in open(file, "r"):
-        line = line[:-1]
-        if isDebLine(line):
-            for old_url, new_url in map.items():
-                if old_url.search(line):
-                    changed = True
-                    new_line = old_url.sub(new_url, line)
-                    verb(f"{line}")
-                    verb(f"-> {new_line}", add=-3)
-                    line = new_line
-                    break
-            else:
-                verb(f"= {line}", add=-2)
         if write_mode:
-            newFile.write(line + "\n")
+            newFile = tempfile.NamedTemporaryFile(mode="w", delete=False)
-    if write_mode:
+            backFilePath = Path(source_file + ".save")
-        origFilePath = Path(file)
+            newFilePath = Path(newFile.name)
-        backFilePath = Path(file + ".save")
+        changed = False
-        newFilePath = Path(newFile.name)
+        with origFilePath.open() as f:
-        newFile.close()
+            for line in f:
-        newFilePath.chmod(0o644)
+                line = line[:-1] # Remove newline character
-        if changed:
+                if isDebLine(line):
-            origFilePath.replace(backFilePath)
+                    for old_pattern, new_url in mapping.items():
-            newFilePath.rename(origFilePath)
+                        old_match = old_pattern.search(line)
-    verbLevel(-1)
+                        if old_match:
+                            changed = True
+                            old_url = old_match.group(0)
+                            verb(f"{line}")
+                            if mirror_mode:
+                                mirror_file = mirror_path / (hashlib.sha256(old_pattern.pattern) + ".lst")
+                                new_line = old_pattern.sub('mirror+file:' + str(mirror_file.resolve()), line)
+                                if write_mode:
+                                    if not mirror_path.exists():
+                                        mirror_path.mkdir()
+                                    if not mirror_file.exists():
+                                        mirror_file.write_text(f"{new_url} priority:1")
+                                        mirror_file.write_text(f"{old_url} priority:9")
+                            else:
+                                new_line = old_pattern.sub(new_url, line)
+                            verb(f"-> {new_line} # {new_url}", add=-3)
+                            line = new_line
+                            break
+                    else:
+                        verb(f"= {line}", add=-2)
+                if write_mode:
+                    newFile.write(line + "\n")
+        if write_mode and changed:
+            newFile.close()
+            newFilePath.chmod(0o644)
+            if changed:
+                origFilePath.replace(backFilePath)
+                newFilePath.rename(origFilePath)
+            else:
+                newFile.unlink()
 
 def main(argv):
     global mirror_mode
+    global mirror_path
     global verbose_mode
     global write_mode
     # Parse arguments
     parser = argparse.ArgumentParser(description="Redirects apt sources to a given approx cache if cached by approx. Only files ending with .list in sources.list.d will be changed.")
     parser.add_argument('host', help="The URL of the approx cache, uses http:// if protocol is omitted")
-    parser.add_argument('-c', '--confirm', action='store_true', dest='confirm', help="Does rewrite the source files to redirect to approx, does require run as root")
+    parser.add_argument('-c', '--confirm', action='store_true', help="Does rewrite the source files to redirect to approx, may does require run as root")
-    parser.add_argument('-m', '--mirror', action='store_true', dest='use_mirror', help="Uses mirror lists to allow falling back to direct connection")
+    parser.add_argument('-m', '--mirror', action='store_true', help="Uses mirror lists to allow falling back to direct connection, mirror lists will be stored to {path}/mirror-lists")
-    parser.add_argument('-p', '--path', dest='path', default='/etc/apt', type=Path, help="Configuration directory of apt containing sources.list files, defaults to /etc/apt")
+    parser.add_argument('-p', '--path', default='/etc/apt', type=Path, help="Configuration directory of apt containing sources.list files, defaults to /etc/apt")
-    parser.add_argument('-v', '--verbose', action='store_true', dest='verbose', help="Displays debug information")
+    parser.add_argument('-v', '--verbose', action='store_true', help="Displays debug information")
     args = parser.parse_args(argv)
     # Check server host
     if not allProtoRegex.match(args.host):
         args.host = "http://" + args.host
     # Store configuration in global vars
-    mirror_mode = args.use_mirror
+    mirror_mode = args.mirror
+    mirror_path = Path(args.path) / 'mirror-lists'
     verbose_mode = args.verbose
     write_mode = args.confirm
     # Retrieve repository map
     verb(f"Connect to {args.host} to retrieve repository list")
     repo_map = modifyMap(discoverMap(args.host))
     verb("Found following repositories:")
-    verbLevel(1)
+    with verbLevelContext():
-    for k, v in repo_map.items():
+        for k, v in repo_map.items():
-        verb(k.pattern)
+            verb(k.pattern)
-    verbLevel(-1)
     # Check for sources files
     file_list = [args.path / 'sources.list'] + [file for file in (args.path / 'sources.list.d').rglob('*.list') if file.is_file()]
     for file in file_list: