[feat] Add OAuth2 support for OpenStreetMap

Fixes python-social-auth#758

social_core/backends/openstreetmap_oauth2.py

@@ -0,0 +1,67 @@
+"""
+OpenStreetMap OAuth 2.0 support.
+
+This adds support for OpenStreetMap OAuth service. An application must be
+registered first on OpenStreetMap and the settings
+SOCIAL_AUTH_OPENSTREETMAP_OAUTH2_KEY and SOCIAL_AUTH_OPENSTREETMAP_OAUTH2_SECRET
+must be defined with the corresponding values.
+
+More info: https://wiki.openstreetmap.org/wiki/OAuth
+"""
+from xml.dom import minidom
+
+from .oauth import BaseOAuth2PKCE
+
+
+class OpenStreetMapOAuth2(BaseOAuth2PKCE):
+    """OpenStreetMap OAuth2 authentication backend"""
+
+    name = "openstreetmap-oauth2"
+    AUTHORIZATION_URL = "https://www.openstreetmap.org/oauth2/authorize"
+    ACCESS_TOKEN_URL = "https://www.openstreetmap.org/oauth2/token"
+    ACCESS_TOKEN_METHOD = "POST"
+    SCOPE_SEPARATOR = " "
+    STATE_PARAMETER = True
+    EXTRA_DATA = [
+        ("id", "id"),
+        ("avatar", "avatar"),
+        ("account_created", "account_created"),
+    ]
+    PKCE_DEFAULT_CODE_CHALLENGE_METHOD = "S256"
+    DEFAULT_USE_PKCE = True
+
+    def get_user_details(self, response):
+        """Return user details from OpenStreetMap account"""
+        return {
+            "username": response["username"],
+            "email": "",
+            "fullname": "",
+            "first_name": "",
+            "last_name": "",
+        }
+
+    def user_data(self, access_token, *args, **kwargs):
+        """Return user data provided"""
+
+        headers = {"Authorization": f"Bearer {access_token}"}
+        response = self.request(
+            url="https://api.openstreetmap.org/api/0.6/user/details",
+            method="GET",
+            headers=headers
+        )
+
+        try:
+            dom = minidom.parseString(response.content)
+        except ValueError:
+            return None
+        user = dom.getElementsByTagName("user")[0]
+        try:
+            avatar = dom.getElementsByTagName("img")[0].getAttribute("href")
+        except IndexError:
+            avatar = None
+        return {
+            "id": user.getAttribute("id"),
+            "username": user.getAttribute("display_name"),
+            "account_created": user.getAttribute("account_created"),
+            "avatar": avatar,
+        }