Implement basic authentication

Initial working implementation, would require more polishing, but at
least it works for now.

config.toml.example

@@ -1,6 +1,8 @@
 name = "Folder share"
 base_path = "/path/to/folder"
 favicon = "/.favicon.png"
+password = "publicpass"
+admin_password = "verysecurepass"
 
 [qbittorrent]
 base_url = "http://127.0.0.1:8080"

src/__init__.py

@@ -2,10 +2,11 @@
 
 import os
 
-from flask import Flask, render_template, send_file, request
+from flask import Flask, Response, render_template, send_file, request
 
 from . import file
 from . import config
+from . import auth
 
 app = Flask(
     __name__,
@@ -21,6 +22,7 @@ app.jinja_env.globals.update(
 
 @app.route('/', defaults={'path': ''})
 @app.route('/<path:path>')
+@auth.requires_auth
 def index(path):
     internal_path = os.path.join(config.get('base_path'), path)
     path = '/' + path
@@ -62,6 +64,7 @@ def index(path):
 
 
 @app.route('/search')
+@auth.requires_auth
 def search():
     q = request.args.get('q', '')
 
@@ -85,3 +88,27 @@ def search():
         ),
         200,
     )
+
+
+@app.route('/auth', methods=['POST'])
+def auth_handle():
+    expected_pass = config.get('password')
+
+    if expected_pass is None:
+        return "You shouldn't be here.", 405
+
+    if request.form.get("pass", None) != expected_pass:
+        return render_template(
+            'auth.html',
+            path=request.form.get("location", "/"),
+            error_msg="Incorrect password",
+        ), 403
+
+    return Response(
+        "Redirecting...",
+        303,
+        {
+            'Location': request.form.get("location", "/"),
+            'Set-Cookie': 'film_session=To be changed',
+        }
+    )

src/auth.py

@@ -0,0 +1,31 @@
+from functools import wraps
+
+from flask import request, render_template
+from . import config
+
+# FIXME: EVERYTHING is under the auth now, even files (makes sense)
+#        but that means that even the favicon requires authentication.
+
+
+def auth_page(*args, **kwargs):
+    # TODO: Is there a better way of doing this?
+    path = f"{request.path}?{request.query_string.decode('utf-8')}"
+
+    return render_template("auth.html", path=path), 403
+
+
+def requires_auth(f):
+    @wraps(f)
+    def decorated(*args, **kwargs):
+        if config.get('password') in [False, None, ""]:
+            return f(*args, **kwargs)
+
+        if request.cookies.get('film_session', None) != 'To be changed':
+            # Not authenticated
+            return auth_page()
+
+        # User properly authenticated
+        print(request.cookies['film_session'])
+        return f(*args, **kwargs)
+
+    return decorated

templates/auth.html

@@ -0,0 +1,13 @@
+{% extends 'base.html' %}
+
+{% block title %}Secret required{% endblock %}
+
+{% block body %}
+<h1>Secret required</h1>
+<form method="POST" action="/auth">
+    <input type="hidden" name="location" value="{{ path }}">
+    <input type="text" name="pass" />
+    <input type="submit" />
+</form>
+<p style="color:red;">{{ error_msg|default('') }}</p>
+{% endblock %}