Add alternate redirect_uri support for broken instances

Pixelfed instances do not handle OOB OAuth correctly meaning you can't
currently login to them using `toot` (e.g. https://github.com/pixelfed/pixelfed/issues/2522 )

This is a fudge to workaround that by allowing you to specify an
alternate `redirect_uri` for broken servers which can take the HTTP
redirect issued by Pixelfed and let you grab the code.

If you don't have a handy HTTP server, you can use `http://localhost`
and your browser (at least Safari and Chrome) will have the code in
the address bar for copying and pasting into `toot`.

toot/__init__.py

@@ -17,6 +17,7 @@ class App(NamedTuple):
     base_url: str
     client_id: str
     client_secret: str
+    redirect_uri: str
 
 
 class User(NamedTuple):

toot/api.py

@@ -77,12 +77,12 @@ def _tag_action(app, user, tag_name, action) -> Response:
     return http.post(app, user, url)
 
 
-def create_app(base_url):
+def create_app(base_url, redirect_uri):
     url = f"{base_url}/api/v1/apps"
 
     json = {
         'client_name': CLIENT_NAME,
-        'redirect_uris': 'urn:ietf:wg:oauth:2.0:oob',
+        'redirect_uris': redirect_uri,
         'scopes': SCOPES,
         'website': CLIENT_WEBSITE,
     }
@@ -157,7 +157,7 @@ def fetch_app_token(app):
         "client_id": app.client_id,
         "client_secret": app.client_secret,
         "grant_type": "client_credentials",
-        "redirect_uri": "urn:ietf:wg:oauth:2.0:oob",
+        "redirect_uri": app.redirect_uri,
         "scope": "read write"
     }
 
@@ -183,7 +183,7 @@ def get_browser_login_url(app: App) -> str:
     """Returns the URL for manual log in via browser"""
     return "{}/oauth/authorize/?{}".format(app.base_url, urlencode({
         "response_type": "code",
-        "redirect_uri": "urn:ietf:wg:oauth:2.0:oob",
+        "redirect_uri": app.redirect_uri,
         "scope": SCOPES,
         "client_id": app.client_id,
     }))
@@ -197,7 +197,7 @@ def request_access_token(app: App, authorization_code: str):
         'client_id': app.client_id,
         'client_secret': app.client_secret,
         'code': authorization_code,
-        'redirect_uri': 'urn:ietf:wg:oauth:2.0:oob',
+        'redirect_uri': app.redirect_uri,
     }
 
     return http.anon_post(url, data=data, allow_redirects=False).json()

toot/auth.py

@@ -12,22 +12,22 @@ def find_instance(base_url: str) -> Instance:
         raise ConsoleError(f"Instance not found at {base_url}")
 
 
-def register_app(domain: str, base_url: str) -> App:
+def register_app(domain: str, base_url: str, redirect_uri: str) -> App:
     try:
-        response = api.create_app(base_url)
+        response = api.create_app(base_url, redirect_uri)
     except ApiError:
         raise ConsoleError("Registration failed.")
 
-    app = App(domain, base_url, response['client_id'], response['client_secret'])
+    app = App(domain, base_url, response['client_id'], response['client_secret'], redirect_uri)
     config.save_app(app)
 
     return app
 
 
-def get_or_create_app(base_url: str) -> App:
+def get_or_create_app(base_url: str, redirect_uri: str) -> App:
     instance = find_instance(base_url)
     domain = _get_instance_domain(instance)
-    return config.load_app(domain) or register_app(domain, base_url)
+    return config.load_app(domain, redirect_uri) or register_app(domain, base_url, redirect_uri)
 
 
 def create_user(app: App, access_token: str) -> User:
@@ -53,8 +53,8 @@ def login_username_password(app: App, email: str, password: str) -> User:
 def login_auth_code(app: App, authorization_code: str) -> User:
     try:
         response = api.request_access_token(app, authorization_code)
-    except Exception:
-        raise ConsoleError("Login failed")
+    except Exception as e:
+        raise ConsoleError("Login failed", e)
 
     return create_user(app, response["access_token"])
 

toot/cli/auth.py

@@ -77,9 +77,11 @@ you need to paste here.""".replace("\n", " ")
 
 @cli.command()
 @instance_option
-def login(base_url: str):
+@click.option("--redirect", "-r", "redirect_uri", help="Redirect URI to use instead of OOB", prompt=True, default="urn:ietf:wg:oauth:2.0:oob")
+def login(base_url: str, redirect_uri: str):
     """Log into an instance using your browser (recommended)"""
-    app = get_or_create_app(base_url)
+    app = get_or_create_app(base_url, redirect_uri)
+    # `redirect_uri` is now stored in `app` for future use / saving.
     url = api.get_browser_login_url(app)
 
     click.echo(click.wrap_text(LOGIN_EXPLANATION))

toot/config.py

@@ -87,10 +87,17 @@ def get_user_app(user_id: str):
     return extract_user_app(load_config(), user_id)
 
 
-def load_app(instance: str) -> Optional[App]:
+def load_app(instance: str, redirect_uri: str) -> Optional[App]:
     config = load_config()
     if instance in config['apps']:
-        return App(**config['apps'][instance])
+        a = App(**config['apps'][instance])
+        # Not sure about this bit - if an app was stored without a `redirect_uri`, should
+        # loading update it to OOB (the previous default) or to the requested `redirect_uri`?
+        # Stick to OOB for now because presumably if we've saved the app, the login must
+        # have worked with OOB and there's no need for a `redirect_uri` update.  Maybe?
+        if a.redirect_uri == "":
+            a.redirect_uri = "urn:ietf:wg:oauth:2.0:oob"
+        return a
 
 
 def load_user(user_id: str, throw=False):