alibi_plugins/oauth/providers/
facebook.rs

1//! Facebook Graph app-bound access tokens and signed Limited Login profiles.
2use super::{
3    OAuthAuthorizationPolicy, OAuthProvider, OAuthTokenEndpointAuth, OAuthUserInfo,
4    OAuthUserInfoHandler, OAuthUserInfoRequest, OAuthUserInfoResponse,
5};
6use crate::oauth::{
7    HttpOAuthJwksSource, OAuthIdTokenConfig, OAuthJwksSelection, OAuthJwksSource,
8    id_token::OAuthNonceComparison,
9};
10use async_trait::async_trait;
11use base64::Engine;
12use serde_json::Map;
13use serde_json::Value;
14use std::sync::Arc;
15
16/// Application-owned Facebook configuration. User-info/refresh callbacks and
17/// signup policies remain configurable on the returned provider.
18#[derive(Clone)]
19pub struct FacebookOptions {
20    pub client_ids: Vec<String>,
21    pub client_secret: Option<String>,
22    /// Sent during authorization-code exchange only.
23    pub client_key: Option<String>,
24    pub scope: Vec<String>,
25    pub disable_default_scope: bool,
26    pub fields: Vec<String>,
27    pub config_id: Option<String>,
28    pub authorization_endpoint: Option<String>,
29    pub redirect_uri: Option<String>,
30    /// Trusted key authority for Limited Login signature verification.
31    pub jwks_source: Option<Arc<dyn OAuthJwksSource>>,
32    /// Trusted transport overrides retain the actual inspection and mapping.
33    pub token_inspection_endpoint: Option<String>,
34    pub user_info_endpoint: Option<String>,
35    pub map_profile_to_user: Option<fn(Value) -> Result<OAuthUserInfo, String>>,
36}
37impl FacebookOptions {
38    #[must_use]
39    pub fn new(client_id: impl Into<String>, client_secret: Option<String>) -> Self {
40        Self {
41            client_ids: vec![client_id.into()],
42            client_secret,
43            client_key: None,
44            scope: Vec::new(),
45            disable_default_scope: false,
46            fields: Vec::new(),
47            config_id: None,
48            authorization_endpoint: None,
49            redirect_uri: None,
50            jwks_source: None,
51            token_inspection_endpoint: None,
52            user_info_endpoint: None,
53            map_profile_to_user: None,
54        }
55    }
56}
57impl std::fmt::Debug for FacebookOptions {
58    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
59        formatter
60            .debug_struct("FacebookOptions")
61            .field("client_ids", &self.client_ids)
62            .field("scope", &self.scope)
63            .field("disable_default_scope", &self.disable_default_scope)
64            .field("fields", &self.fields)
65            .field("config_id", &self.config_id)
66            .field("authorization_endpoint", &self.authorization_endpoint)
67            .field("redirect_uri", &self.redirect_uri)
68            .finish_non_exhaustive()
69    }
70}
71impl OAuthProvider {
72    #[must_use]
73    pub fn facebook(client_id: &str, client_secret: &str) -> Self {
74        Self::facebook_with_options(FacebookOptions::new(client_id, Some(client_secret.into())))
75    }
76    #[must_use]
77    pub fn facebook_with_options(options: FacebookOptions) -> Self {
78        let client_id = options.client_ids.first().cloned().unwrap_or_default();
79        let secret = options.client_secret.unwrap_or_default();
80        let endpoint = options
81            .user_info_endpoint
82            .unwrap_or_else(|| "https://graph.facebook.com/me".into());
83        let verification = OAuthIdTokenConfig {
84            issuers: vec!["https://www.facebook.com".into()],
85            audience: None,
86            client_ids: Some(options.client_ids.clone()),
87            jwks_source: options.jwks_source.unwrap_or_else(|| {
88                Arc::new(HttpOAuthJwksSource::new(
89                    "https://limited.facebook.com/.well-known/oauth/openid/jwks/",
90                ))
91            }),
92            max_age_secs: None,
93            allow_opaque_token: true,
94            algorithm: Some(jsonwebtoken::Algorithm::RS256),
95            selection: OAuthJwksSelection::RemoteRs256,
96            nonce_comparison: OAuthNonceComparison::Exact,
97            verify_claims: None,
98        };
99        Self {
100            client_id: client_id.clone(),
101            client_secret: secret.clone(),
102            additional_client_ids: options.client_ids.iter().skip(1).cloned().collect(),
103            hosted_domain: None,
104            require_email_verification: false,
105            auth_url: options
106                .authorization_endpoint
107                .filter(|value| !value.is_empty())
108                .unwrap_or_else(|| "https://www.facebook.com/v24.0/dialog/oauth".into()),
109            token_url: "https://graph.facebook.com/v24.0/oauth/access_token".into(),
110            user_info_url: Some(endpoint.clone()),
111            scopes: vec!["email".into(), "public_profile".into()],
112            authorization: Some(OAuthAuthorizationPolicy {
113                configured_scopes: options.scope,
114                disable_default_scopes: options.disable_default_scope,
115                require_client_id: true,
116                require_client_secret: true,
117                token_endpoint_auth: Some(OAuthTokenEndpointAuth::ClientSecretPost),
118                authorization_code_client_key: options.client_key,
119                redirect_uri: options.redirect_uri,
120                pkce: false,
121                ..OAuthAuthorizationPolicy::default()
122            }),
123            allowed_request_params: Vec::new(),
124            authorization_params: options
125                .config_id
126                .filter(|value| !value.is_empty())
127                .map(|value| vec![("config_id".into(), value)])
128                .unwrap_or_default(),
129            account_subject: Some(subject),
130            map_user_info: None,
131            get_user_info: Some(Arc::new(FacebookUserInfo {
132                client_id,
133                client_ids: options.client_ids,
134                client_secret: secret,
135                inspection_endpoint: options
136                    .token_inspection_endpoint
137                    .unwrap_or_else(|| "https://graph.facebook.com/debug_token".into()),
138                endpoint,
139                fields: options.fields,
140                mapper: options.map_profile_to_user,
141            })),
142            refresh_access_token: None,
143            verify_id_token: None,
144            id_token: Some(verification),
145            disable_id_token_sign_in: false,
146            disable_implicit_sign_up: false,
147            disable_sign_up: false,
148            allow_idp_initiated: false,
149            override_user_info_on_sign_in: false,
150        }
151    }
152}
153struct FacebookUserInfo {
154    client_id: String,
155    client_ids: Vec<String>,
156    client_secret: String,
157    inspection_endpoint: String,
158    endpoint: String,
159    fields: Vec<String>,
160    mapper: Option<fn(Value) -> Result<OAuthUserInfo, String>>,
161}
162#[async_trait]
163impl OAuthUserInfoHandler for FacebookUserInfo {
164    async fn get_user_info(
165        &self,
166        request: OAuthUserInfoRequest,
167    ) -> Result<OAuthUserInfoResponse, String> {
168        let limited_login = request
169            .id_token
170            .as_deref()
171            .is_some_and(|token| token.split('.').count() == 3);
172        let profile = if limited_login {
173            let token = request
174                .id_token
175                .as_deref()
176                .ok_or("Missing Facebook ID token")?;
177            let payload = token.split('.').nth(1).ok_or("Invalid Facebook ID token")?;
178            let bytes = base64::engine::general_purpose::URL_SAFE_NO_PAD
179                .decode(payload)
180                .map_err(|error| error.to_string())?;
181            let data: Value =
182                alibi_core::utils::json::from_slice(&bytes).map_err(|error| error.to_string())?;
183            if !data.is_object() {
184                return Err("Invalid Facebook ID profile".into());
185            }
186            data
187        } else {
188            self.graph_profile(request.access_token.as_deref()).await?
189        };
190        let mapped = self
191            .mapper
192            .map(|mapper| mapper(profile.clone()))
193            .transpose()?;
194        let user_output = mapped.as_ref().map(|user| user.public_profile(true));
195        let user = match mapped {
196            Some(user) => user,
197            None => OAuthUserInfo {
198                additional_fields: Map::default(),
199                id: scalar(profile.get("sub").or_else(|| profile.get("id")))?.unwrap_or_default(),
200                name: scalar(profile.get("name"))?,
201                email: profile
202                    .get("email")
203                    .and_then(Value::as_str)
204                    .unwrap_or_default()
205                    .into(),
206                image: scalar(if limited_login {
207                    profile.get("picture")
208                } else {
209                    profile
210                        .get("picture")
211                        .and_then(|picture| picture.get("data"))
212                        .and_then(|data| data.get("url"))
213                })?,
214                email_verified: !limited_login
215                    && profile
216                        .get("email_verified")
217                        .and_then(Value::as_bool)
218                        .unwrap_or(false),
219            },
220        };
221        Ok(OAuthUserInfoResponse {
222            user_output,
223            user,
224            data: profile,
225        })
226    }
227}
228impl FacebookUserInfo {
229    async fn graph_profile(&self, access_token: Option<&str>) -> Result<Value, String> {
230        let access_token = access_token
231            .filter(|token| !token.is_empty())
232            .ok_or("Missing Facebook access token")?;
233        if self.client_id.is_empty() || self.client_secret.is_empty() {
234            return Err("Facebook client ID and secret are required".into());
235        }
236        let client = reqwest::Client::new();
237        let app_access_token = format!("{}|{}", self.client_id, self.client_secret);
238        let inspected: Value = client
239            .get(&self.inspection_endpoint)
240            .query(&[
241                ("input_token", access_token),
242                ("access_token", app_access_token.as_str()),
243            ])
244            .send()
245            .await
246            .map_err(http_error)?
247            .error_for_status()
248            .map_err(http_error)?
249            .json()
250            .await
251            .map_err(http_error)?;
252        let data = inspected
253            .get("data")
254            .ok_or("Facebook inspection returned no data")?;
255        let app_valid = data
256            .get("app_id")
257            .and_then(Value::as_str)
258            .is_some_and(|id| {
259                !id.is_empty() && self.client_ids.iter().any(|configured| configured == id)
260            });
261        if data.get("is_valid").and_then(Value::as_bool) != Some(true) || !app_valid {
262            return Err("Invalid Facebook token or configured app binding".into());
263        }
264        let user_id = data
265            .get("user_id")
266            .filter(|value| {
267                matches!(value, Value::String(_) | Value::Number(_) | Value::Bool(_))
268                    && truthy(value)
269            })
270            .ok_or("Facebook inspection returned no user")?;
271        let mut fields = vec!["id", "name", "email", "picture"];
272        fields.extend(self.fields.iter().map(String::as_str));
273        let profile: Value = client
274            .get(&self.endpoint)
275            .query(&[("fields", fields.join(","))])
276            .bearer_auth(access_token)
277            .send()
278            .await
279            .map_err(http_error)?
280            .error_for_status()
281            .map_err(http_error)?
282            .json()
283            .await
284            .map_err(http_error)?;
285        if profile.get("id") != Some(user_id) {
286            return Err("Facebook profile does not match inspected identity".into());
287        }
288        Ok(profile)
289    }
290}
291fn http_error(error: reqwest::Error) -> String {
292    error.without_url().to_string()
293}
294fn truthy(value: &Value) -> bool {
295    match value {
296        Value::Null => false,
297        Value::Bool(value) => *value,
298        Value::Number(value) => value.as_f64().is_some_and(|value| value != 0.0),
299        Value::String(value) => !value.is_empty(),
300        Value::Array(_) | Value::Object(_) => true,
301    }
302}
303fn scalar(value: Option<&Value>) -> Result<Option<String>, String> {
304    match value {
305        None | Some(Value::Null) => Ok(None),
306        Some(Value::String(value)) => Ok(Some(value.clone())),
307        Some(Value::Number(value)) => alibi_core::utils::json::number_to_string(value)
308            .map(Some)
309            .map_err(|error| error.to_string()),
310        Some(Value::Bool(value)) => Ok(Some(value.to_string())),
311        Some(Value::Array(_) | Value::Object(_)) => Err("Invalid Facebook profile field".into()),
312    }
313}
314fn subject(profile: &Value) -> Result<String, String> {
315    let id = scalar(profile.get("sub").or_else(|| profile.get("id")))?
316        .ok_or("Missing Facebook account subject")?;
317    if id
318        .trim_matches(|character: char| {
319            (character.is_whitespace() && character != '\u{85}') || character == '\u{feff}'
320        })
321        .is_empty()
322        || id == "null"
323        || id == "undefined"
324    {
325        return Err("Invalid Facebook account subject".into());
326    }
327    Ok(id)
328}
alibi_plugins/oauth/providers/facebook.rs

alibi_plugins/oauth/providers/
facebook.rs
