from typing import Any, Dict, List, Optional, Union, cast
from fastapi.exceptions import HTTPException
from fastapi.openapi.models import OAuth2 as OAuth2Model
from fastapi.openapi.models import OAuthFlows as OAuthFlowsModel
from fastapi.param_functions import Form
from fastapi.security.base import SecurityBase
from fastapi.security.utils import get_authorization_scheme_param
from starlette.requests import Request
from starlette.status import HTTP_401_UNAUTHORIZED, HTTP_403_FORBIDDEN
# TODO: import from typing when deprecating Python 3.9
from typing_extensions import Annotated, Doc
class OAuth2PasswordRequestForm:
"""
This is a dependency class to collect the `username` and `password` as form data
for an OAuth2 password flow.
The OAuth2 specification dictates that for a password flow the data should be
collected using form data (instead of JSON) and that it should have the specific
fields `username` and `password`.
All the initialization parameters are extracted from the request.
Read more about it in the
[FastAPI docs for Simple OAuth2 with Password and Bearer](https://fastapi.tiangolo.com/tutorial/security/simple-oauth2/).
## Example
```python
from typing import Annotated
from fastapi import Depends, FastAPI
from fastapi.security import OAuth2PasswordRequestForm
app = FastAPI()
@app.post("/login")
def login(form_data: Annotated[OAuth2PasswordRequestForm, Depends()]):
data = {}
data["scopes"] = []
for scope in form_data.scopes:
data["scopes"].append(scope)
if form_data.client_id:
data["client_id"] = form_data.client_id
if form_data.client_secret:
data["client_secret"] = form_data.client_secret
return data
```
Note that for OAuth2 the scope `items:read` is a single scope in an opaque string.
You could have custom internal logic to separate it by colon characters (`:`) or
similar, and get the two parts `items` and `read`. Many applications do that to
group and organize permissions, you could do it as well in your application, just
know that that it is application specific, it's not part of the specification.
"""
def __init__(
self,
*,
grant_type: Annotated[
Union[str, None],
Form(pattern="^password$"),
Doc(
"""
The OAuth2 spec says it is required and MUST be the fixed string
"password". Nevertheless, this dependency class is permissive and
allows not passing it. If you want to enforce it, use instead the
`OAuth2PasswordRequestFormStrict` dependency.
"""
),
] = None,
username: Annotated[
str,
Form(),
Doc(
"""
`username` string. The OAuth2 spec requires the exact field name
`username`.
"""
),
],
password: Annotated[
str,
Form(),
Doc(
"""
`password` string. The OAuth2 spec requires the exact field name
`password".
"""
),
],
scope: Annotated[
str,
Form(),
Doc(
"""
A single string with actually several scopes separated by spaces. Each
scope is also a string.
For example, a single string with:
```python
"items:read items:write users:read profile openid"
````
would represent the scopes:
* `items:read`
* `items:write`
* `users:read`
* `profile`
* `openid`
"""
),
] = "",
client_id: Annotated[
Union[str, None],
Form(),
Doc(
"""
If there's a `client_id`, it can be sent as part of the form fields.
But the OAuth2 specification recommends sending the `client_id` and
`client_secret` (if any) using HTTP Basic auth.
"""
),
] = None,
client_secret: Annotated[
Union[str, None],
Form(),
Doc(
"""
If there's a `client_password` (and a `client_id`), they can be sent
as part of the form fields. But the OAuth2 specification recommends
sending the `client_id` and `client_secret` (if any) using HTTP Basic
auth.
"""
),
] = None,
):
self.grant_type = grant_type
self.username = username
self.password = password
self.scopes = scope.split()
self.client_id = client_id
self.client_secret = client_secret
class OAuth2PasswordRequestFormStrict(OAuth2PasswordRequestForm):
"""
This is a dependency class to collect the `username` and `password` as form data
for an OAuth2 password flow.
The OAuth2 specification dictates that for a password flow the data should be
collected using form data (instead of JSON) and that it should have the specific
fields `username` and `password`.
All the initialization parameters are extracted from the request.
The only difference between `OAuth2PasswordRequestFormStrict` and
`OAuth2PasswordRequestForm` is that `OAuth2PasswordRequestFormStrict` requires the
client to send the form field `grant_type` with the value `"password"`, which
is required in the OAuth2 specification (it seems that for no particular reason),
while for `OAuth2PasswordRequestForm` `grant_type` is optional.
Read more about it in the
[FastAPI docs for Simple OAuth2 with Password and Bearer](https://fastapi.tiangolo.com/tutorial/security/simple-oauth2/).
## Example
```python
from typing import Annotated
from fastapi import Depends, FastAPI
from fastapi.security import OAuth2PasswordRequestForm
app = FastAPI()
@app.post("/login")
def login(form_data: Annotated[OAuth2PasswordRequestFormStrict, Depends()]):
data = {}
data["scopes"] = []
for scope in form_data.scopes:
data["scopes"].append(scope)
if form_data.client_id:
data["client_id"] = form_data.client_id
if form_data.client_secret:
data["client_secret"] = form_data.client_secret
return data
```
Note that for OAuth2 the scope `items:read` is a single scope in an opaque string.
You could have custom internal logic to separate it by colon characters (`:`) or
similar, and get the two parts `items` and `read`. Many applications do that to
group and organize permissions, you could do it as well in your application, just
know that that it is application specific, it's not part of the specification.
grant_type: the OAuth2 spec says it is required and MUST be the fixed string "password".
This dependency is strict about it. If you want to be permissive, use instead the
OAuth2PasswordRequestForm dependency class.
username: username string. The OAuth2 spec requires the exact field name "username".
password: password string. The OAuth2 spec requires the exact field name "password".
scope: Optional string. Several scopes (each one a string) separated by spaces. E.g.
"items:read items:write users:read profile openid"
client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
using HTTP Basic auth, as: client_id:client_secret
client_secret: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
using HTTP Basic auth, as: client_id:client_secret
"""
def __init__(
self,
grant_type: Annotated[
str,
Form(pattern="^password$"),
Doc(
"""
The OAuth2 spec says it is required and MUST be the fixed string
"password". This dependency is strict about it. If you want to be
permissive, use instead the `OAuth2PasswordRequestForm` dependency
class.
"""
),
],
username: Annotated[
str,
Form(),
Doc(
"""
`username` string. The OAuth2 spec requires the exact field name
`username`.
"""
),
],
password: Annotated[
str,
Form(),
Doc(
"""
`password` string. The OAuth2 spec requires the exact field name
`password".
"""
),
],
scope: Annotated[
str,
Form(),
Doc(
"""
A single string with actually several scopes separated by spaces. Each
scope is also a string.
For example, a single string with:
```python
"items:read items:write users:read profile openid"
````
would represent the scopes:
* `items:read`
* `items:write`
* `users:read`
* `profile`
* `openid`
"""
),
] = "",
client_id: Annotated[
Union[str, None],
Form(),
Doc(
"""
If there's a `client_id`, it can be sent as part of the form fields.
But the OAuth2 specification recommends sending the `client_id` and
`client_secret` (if any) using HTTP Basic auth.
"""
),
] = None,
client_secret: Annotated[
Union[str, None],
Form(),
Doc(
"""
If there's a `client_password` (and a `client_id`), they can be sent
as part of the form fields. But the OAuth2 specification recommends
sending the `client_id` and `client_secret` (if any) using HTTP Basic
auth.
"""
),
] = None,
):
super().__init__(
grant_type=grant_type,
username=username,
password=password,
scope=scope,
client_id=client_id,
client_secret=client_secret,
)
class OAuth2(SecurityBase):
"""
This is the base class for OAuth2 authentication, an instance of it would be used
as a dependency. All other OAuth2 classes inherit from it and customize it for
each OAuth2 flow.
You normally would not create a new class inheriting from it but use one of the
existing subclasses, and maybe compose them if you want to support multiple flows.
Read more about it in the
[FastAPI docs for Security](https://fastapi.tiangolo.com/tutorial/security/).
"""
def __init__(
self,
*,
flows: Annotated[
Union[OAuthFlowsModel, Dict[str, Dict[str, Any]]],
Doc(
"""
The dictionary of OAuth2 flows.
"""
),
] = OAuthFlowsModel(),
scheme_name: Annotated[
Optional[str],
Doc(
"""
Security scheme name.
It will be included in the generated OpenAPI (e.g. visible at `/docs`).
"""
),
] = None,
description: Annotated[
Optional[str],
Doc(
"""
Security scheme description.
It will be included in the generated OpenAPI (e.g. visible at `/docs`).
"""
),
] = None,
auto_error: Annotated[
bool,
Doc(
"""
By default, if no HTTP Authorization header is provided, required for
OAuth2 authentication, it will automatically cancel the request and
send the client an error.
If `auto_error` is set to `False`, when the HTTP Authorization header
is not available, instead of erroring out, the dependency result will
be `None`.
This is useful when you want to have optional authentication.
It is also useful when you want to have authentication that can be
provided in one of multiple optional ways (for example, with OAuth2
or in a cookie).
"""
),
] = True,
):
self.model = OAuth2Model(
flows=cast(OAuthFlowsModel, flows), description=description
)
self.scheme_name = scheme_name or self.__class__.__name__
self.auto_error = auto_error
async def __call__(self, request: Request) -> Optional[str]:
authorization = request.headers.get("Authorization")
if not authorization:
if self.auto_error:
raise HTTPException(
status_code=HTTP_403_FORBIDDEN, detail="Not authenticated"
)
else:
return None
return authorization
class OAuth2PasswordBearer(OAuth2):
"""
OAuth2 flow for authentication using a bearer token obtained with a password.
An instance of it would be used as a dependency.
Read more about it in the
[FastAPI docs for Simple OAuth2 with Password and Bearer](https://fastapi.tiangolo.com/tutorial/security/simple-oauth2/).
"""
def __init__(
self,
tokenUrl: Annotated[
str,
Doc(
"""
The URL to obtain the OAuth2 token. This would be the *path operation*
that has `OAuth2PasswordRequestForm` as a dependency.
"""
),
],
scheme_name: Annotated[
Optional[str],
Doc(
"""
Security scheme name.
It will be included in the generated OpenAPI (e.g. visible at `/docs`).
"""
),
] = None,
scopes: Annotated[
Optional[Dict[str, str]],
Doc(
"""
The OAuth2 scopes that would be required by the *path operations* that
use this dependency.
"""
),
] = None,
description: Annotated[
Optional[str],
Doc(
"""
Security scheme description.
It will be included in the generated OpenAPI (e.g. visible at `/docs`).
"""
),
] = None,
auto_error: Annotated[
bool,
Doc(
"""
By default, if no HTTP Authorization header is provided, required for
OAuth2 authentication, it will automatically cancel the request and
send the client an error.
If `auto_error` is set to `False`, when the HTTP Authorization header
is not available, instead of erroring out, the dependency result will
be `None`.
This is useful when you want to have optional authentication.
It is also useful when you want to have authentication that can be
provided in one of multiple optional ways (for example, with OAuth2
or in a cookie).
"""
),
] = True,
):
if not scopes:
scopes = {}
flows = OAuthFlowsModel(
password=cast(Any, {"tokenUrl": tokenUrl, "scopes": scopes})
)
super().__init__(
flows=flows,
scheme_name=scheme_name,
description=description,
auto_error=auto_error,
)
async def __call__(self, request: Request) -> Optional[str]:
authorization = request.headers.get("Authorization")
scheme, param = get_authorization_scheme_param(authorization)
if not authorization or scheme.lower() != "bearer":
if self.auto_error:
raise HTTPException(
status_code=HTTP_401_UNAUTHORIZED,
detail="Not authenticated",
headers={"WWW-Authenticate": "Bearer"},
)
else:
return None
return param
class OAuth2AuthorizationCodeBearer(OAuth2):
"""
OAuth2 flow for authentication using a bearer token obtained with an OAuth2 code
flow. An instance of it would be used as a dependency.
"""
def __init__(
self,
authorizationUrl: str,
tokenUrl: Annotated[
str,
Doc(
"""
The URL to obtain the OAuth2 token.
"""
),
],
refreshUrl: Annotated[
Optional[str],
Doc(
"""
The URL to refresh the token and obtain a new one.
"""
),
] = None,
scheme_name: Annotated[
Optional[str],
Doc(
"""
Security scheme name.
It will be included in the generated OpenAPI (e.g. visible at `/docs`).
"""
),
] = None,
scopes: Annotated[
Optional[Dict[str, str]],
Doc(
"""
The OAuth2 scopes that would be required by the *path operations* that
use this dependency.
"""
),
] = None,
description: Annotated[
Optional[str],
Doc(
"""
Security scheme description.
It will be included in the generated OpenAPI (e.g. visible at `/docs`).
"""
),
] = None,
auto_error: Annotated[
bool,
Doc(
"""
By default, if no HTTP Authorization header is provided, required for
OAuth2 authentication, it will automatically cancel the request and
send the client an error.
If `auto_error` is set to `False`, when the HTTP Authorization header
is not available, instead of erroring out, the dependency result will
be `None`.
This is useful when you want to have optional authentication.
It is also useful when you want to have authentication that can be
provided in one of multiple optional ways (for example, with OAuth2
or in a cookie).
"""
),
] = True,
):
if not scopes:
scopes = {}
flows = OAuthFlowsModel(
authorizationCode=cast(
Any,
{
"authorizationUrl": authorizationUrl,
"tokenUrl": tokenUrl,
"refreshUrl": refreshUrl,
"scopes": scopes,
},
)
)
super().__init__(
flows=flows,
scheme_name=scheme_name,
description=description,
auto_error=auto_error,
)
async def __call__(self, request: Request) -> Optional[str]:
authorization = request.headers.get("Authorization")
scheme, param = get_authorization_scheme_param(authorization)
if not authorization or scheme.lower() != "bearer":
if self.auto_error:
raise HTTPException(
status_code=HTTP_401_UNAUTHORIZED,
detail="Not authenticated",
headers={"WWW-Authenticate": "Bearer"},
)
else:
return None # pragma: nocover
return param
class SecurityScopes:
"""
This is a special class that you can define in a parameter in a dependency to
obtain the OAuth2 scopes required by all the dependencies in the same chain.
This way, multiple dependencies can have different scopes, even when used in the
same *path operation*. And with this, you can access all the scopes required in
all those dependencies in a single place.
Read more about it in the
[FastAPI docs for OAuth2 scopes](https://fastapi.tiangolo.com/advanced/security/oauth2-scopes/).
"""
def __init__(
self,
scopes: Annotated[
Optional[List[str]],
Doc(
"""
This will be filled by FastAPI.
"""
),
] = None,
):
self.scopes: Annotated[
List[str],
Doc(
"""
The list of all the scopes required by dependencies.
"""
),
] = scopes or []
self.scope_str: Annotated[
str,
Doc(
"""
All the scopes required by all the dependencies in a single string
separated by spaces, as defined in the OAuth2 specification.
"""
),
] = " ".join(self.scopes)
