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    /// Application user-info resolution. A client-submitted access token, or an
37    /// opaque ID token, must first be bound to a configured app.
38    pub get_user_info: Option<Arc<dyn OAuthUserInfoHandler>>,
39}
40impl FacebookOptions {
41    #[must_use]
42    pub fn new(client_id: impl Into<String>, client_secret: Option<String>) -> Self {
43        Self {
44            client_ids: vec![client_id.into()],
45            client_secret,
46            client_key: None,
47            scope: Vec::new(),
48            disable_default_scope: false,
49            fields: Vec::new(),
50            config_id: None,
51            authorization_endpoint: None,
52            redirect_uri: None,
53            jwks_source: None,
54            token_inspection_endpoint: None,
55            user_info_endpoint: None,
56            map_profile_to_user: None,
57            get_user_info: None,
58        }
59    }
60}
61impl std::fmt::Debug for FacebookOptions {
62    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
63        formatter
64            .debug_struct("FacebookOptions")
65            .field("client_ids", &self.client_ids)
66            .field("scope", &self.scope)
67            .field("disable_default_scope", &self.disable_default_scope)
68            .field("fields", &self.fields)
69            .field("config_id", &self.config_id)
70            .field("authorization_endpoint", &self.authorization_endpoint)
71            .field("redirect_uri", &self.redirect_uri)
72            .finish_non_exhaustive()
73    }
74}
75impl OAuthProvider {
76    #[must_use]
77    pub fn facebook(client_id: &str, client_secret: &str) -> Self {
78        Self::facebook_with_options(FacebookOptions::new(client_id, Some(client_secret.into())))
79    }
80    #[must_use]
81    pub fn facebook_with_options(options: FacebookOptions) -> Self {
82        let client_id = options.client_ids.first().cloned().unwrap_or_default();
83        let secret = options.client_secret.unwrap_or_default();
84        let endpoint = options
85            .user_info_endpoint
86            .unwrap_or_else(|| "https://graph.facebook.com/me".into());
87        let verification = OAuthIdTokenConfig {
88            issuers: vec!["https://www.facebook.com".into()],
89            audience: None,
90            client_ids: Some(options.client_ids.clone()),
91            jwks_source: options.jwks_source.unwrap_or_else(|| {
92                Arc::new(HttpOAuthJwksSource::new(
93                    "https://limited.facebook.com/.well-known/oauth/openid/jwks/",
94                ))
95            }),
96            max_age_secs: None,
97            allow_opaque_token: true,
98            algorithm: Some(jsonwebtoken::Algorithm::RS256),
99            algorithms: Some(vec![jsonwebtoken::Algorithm::RS256]),
100            default_key_algorithm: None,
101            selection: OAuthJwksSelection::RemoteRs256,
102            nonce_comparison: OAuthNonceComparison::Exact,
103            verify_claims: None,
104        };
105        Self {
106            client_id: client_id.clone(),
107            client_secret: secret.clone(),
108            additional_client_ids: options.client_ids.iter().skip(1).cloned().collect(),
109            hosted_domain: None,
110            require_email_verification: false,
111            auth_url: options
112                .authorization_endpoint
113                .filter(|value| !value.is_empty())
114                .unwrap_or_else(|| "https://www.facebook.com/v24.0/dialog/oauth".into()),
115            token_url: "https://graph.facebook.com/v24.0/oauth/access_token".into(),
116            user_info_url: Some(endpoint.clone()),
117            scopes: vec!["email".into(), "public_profile".into()],
118            authorization: Some(OAuthAuthorizationPolicy {
119                configured_scopes: options.scope,
120                disable_default_scopes: options.disable_default_scope,
121                require_client_id: true,
122                require_client_secret: true,
123                token_endpoint_auth: Some(OAuthTokenEndpointAuth::ClientSecretPost),
124                authorization_code_client_key: options.client_key,
125                redirect_uri: options.redirect_uri,
126                pkce: false,
127                ..OAuthAuthorizationPolicy::default()
128            }),
129            allowed_request_params: Vec::new(),
130            authorization_params: options
131                .config_id
132                .filter(|value| !value.is_empty())
133                .map(|value| vec![("config_id".into(), value)])
134                .unwrap_or_default(),
135            account_subject: Some(subject),
136            map_user_info: None,
137            get_user_info: Some(Arc::new(FacebookUserInfo {
138                client_id,
139                client_ids: options.client_ids,
140                client_secret: secret,
141                inspection_endpoint: options
142                    .token_inspection_endpoint
143                    .unwrap_or_else(|| "https://graph.facebook.com/debug_token".into()),
144                endpoint,
145                fields: options.fields,
146                mapper: options.map_profile_to_user,
147                custom: options.get_user_info,
148            })),
149            refresh_access_token: None,
150            verify_id_token: None,
151            id_token: Some(verification),
152            disable_id_token_sign_in: false,
153            disable_implicit_sign_up: false,
154            disable_sign_up: false,
155            allow_idp_initiated: false,
156            override_user_info_on_sign_in: false,
157        }
158    }
159}
160struct FacebookUserInfo {
161    client_id: String,
162    client_ids: Vec<String>,
163    client_secret: String,
164    inspection_endpoint: String,
165    endpoint: String,
166    fields: Vec<String>,
167    mapper: Option<fn(Value) -> Result<OAuthUserInfo, String>>,
168    custom: Option<Arc<dyn OAuthUserInfoHandler>>,
169}
170#[async_trait]
171impl OAuthUserInfoHandler for FacebookUserInfo {
172    async fn get_user_info(
173        &self,
174        request: OAuthUserInfoRequest,
175    ) -> Result<OAuthUserInfoResponse, String> {
176        if let Some(custom) = &self.custom {
177            // On the client sign-in path the access token, or an opaque ID token,
178            // arrives unverified, so bind it to this app before the application
179            // resolves identity from it.
180            let opaque_id_token = request
181                .id_token
182                .as_deref()
183                .filter(|token| !token.is_empty() && token.split('.').count() != 3);
184            if let Some(token) = request
185                .access_token
186                .as_deref()
187                .filter(|token| !token.is_empty())
188                .or(opaque_id_token)
189            {
190                _ = self.inspect(token).await?;
191            }
192            return custom.get_user_info(request).await;
193        }
194        let limited_login = request
195            .id_token
196            .as_deref()
197            .is_some_and(|token| token.split('.').count() == 3);
198        let profile = if limited_login {
199            let token = request
200                .id_token
201                .as_deref()
202                .ok_or("Missing Facebook ID token")?;
203            let payload = token.split('.').nth(1).ok_or("Invalid Facebook ID token")?;
204            let bytes = base64::engine::general_purpose::URL_SAFE_NO_PAD
205                .decode(payload)
206                .map_err(|error| error.to_string())?;
207            let data: Value =
208                alibi_core::utils::json::from_slice(&bytes).map_err(|error| error.to_string())?;
209            if !data.is_object() {
210                return Err("Invalid Facebook ID profile".into());
211            }
212            data
213        } else {
214            self.graph_profile(request.access_token.as_deref()).await?
215        };
216        let mapped = self
217            .mapper
218            .map(|mapper| mapper(profile.clone()))
219            .transpose()?;
220        let user_output = mapped.as_ref().map(|user| user.public_profile(true));
221        let user = match mapped {
222            Some(user) => user,
223            None => OAuthUserInfo {
224                additional_fields: Map::default(),
225                id: scalar(profile.get("sub").or_else(|| profile.get("id")))?.unwrap_or_default(),
226                name: scalar(profile.get("name"))?,
227                email: profile
228                    .get("email")
229                    .and_then(Value::as_str)
230                    .unwrap_or_default()
231                    .into(),
232                image: scalar(if limited_login {
233                    profile.get("picture")
234                } else {
235                    profile
236                        .get("picture")
237                        .and_then(|picture| picture.get("data"))
238                        .and_then(|data| data.get("url"))
239                })?,
240                email_verified: !limited_login
241                    && profile
242                        .get("email_verified")
243                        .and_then(Value::as_bool)
244                        .unwrap_or(false),
245            },
246        };
247        Ok(OAuthUserInfoResponse {
248            user_output,
249            user,
250            data: profile,
251        })
252    }
253}
254impl FacebookUserInfo {
255    async fn graph_profile(&self, access_token: Option<&str>) -> Result<Value, String> {
256        let access_token = access_token
257            .filter(|token| !token.is_empty())
258            .ok_or("Missing Facebook access token")?;
259        let user_id = self.inspect(access_token).await?;
260        let mut fields = vec!["id", "name", "email", "picture"];
261        fields.extend(self.fields.iter().map(String::as_str));
262        let profile: Value = reqwest::Client::new()
263            .get(&self.endpoint)
264            .query(&[("fields", fields.join(","))])
265            .bearer_auth(access_token)
266            .send()
267            .await
268            .map_err(http_error)?
269            .error_for_status()
270            .map_err(http_error)?
271            .json()
272            .await
273            .map_err(http_error)?;
274        if profile.get("id") != Some(&user_id) {
275            return Err("Facebook profile does not match inspected identity".into());
276        }
277        Ok(profile)
278    }
279    /// Binds `access_token` to a configured app and returns its user ID.
280    async fn inspect(&self, access_token: &str) -> Result<Value, String> {
281        if self.client_id.is_empty() || self.client_secret.is_empty() {
282            return Err("Facebook client ID and secret are required".into());
283        }
284        let app_access_token = format!("{}|{}", self.client_id, self.client_secret);
285        let inspected: Value = reqwest::Client::new()
286            .get(&self.inspection_endpoint)
287            .query(&[
288                ("input_token", access_token),
289                ("access_token", app_access_token.as_str()),
290            ])
291            .send()
292            .await
293            .map_err(http_error)?
294            .error_for_status()
295            .map_err(http_error)?
296            .json()
297            .await
298            .map_err(http_error)?;
299        let data = inspected
300            .get("data")
301            .ok_or("Facebook inspection returned no data")?;
302        let app_valid = data
303            .get("app_id")
304            .and_then(Value::as_str)
305            .is_some_and(|id| {
306                !id.is_empty() && self.client_ids.iter().any(|configured| configured == id)
307            });
308        if data.get("is_valid").and_then(Value::as_bool) != Some(true) || !app_valid {
309            return Err("Invalid Facebook token or configured app binding".into());
310        }
311        let user_id = data
312            .get("user_id")
313            .filter(|value| {
314                matches!(value, Value::String(_) | Value::Number(_) | Value::Bool(_))
315                    && truthy(value)
316            })
317            .ok_or("Facebook inspection returned no user")?;
318        Ok(user_id.clone())
319    }
320}
321fn http_error(error: reqwest::Error) -> String {
322    error.without_url().to_string()
323}
324fn truthy(value: &Value) -> bool {
325    match value {
326        Value::Null => false,
327        Value::Bool(value) => *value,
328        Value::Number(value) => value.as_f64().is_some_and(|value| value != 0.0),
329        Value::String(value) => !value.is_empty(),
330        Value::Array(_) | Value::Object(_) => true,
331    }
332}
333fn scalar(value: Option<&Value>) -> Result<Option<String>, String> {
334    match value {
335        None | Some(Value::Null) => Ok(None),
336        Some(Value::String(value)) => Ok(Some(value.clone())),
337        Some(Value::Number(value)) => alibi_core::utils::json::number_to_string(value)
338            .map(Some)
339            .map_err(|error| error.to_string()),
340        Some(Value::Bool(value)) => Ok(Some(value.to_string())),
341        Some(Value::Array(_) | Value::Object(_)) => Err("Invalid Facebook profile field".into()),
342    }
343}
344fn subject(profile: &Value) -> Result<String, String> {
345    let id = scalar(profile.get("sub").or_else(|| profile.get("id")))?
346        .ok_or("Missing Facebook account subject")?;
347    if id
348        .trim_matches(|character: char| {
349            (character.is_whitespace() && character != '\u{85}') || character == '\u{feff}'
350        })
351        .is_empty()
352        || id == "null"
353        || id == "undefined"
354    {
355        return Err("Invalid Facebook account subject".into());
356    }
357    Ok(id)
358}
alibi_plugins/oauth/providers/facebook.rs

alibi_plugins/oauth/providers/
facebook.rs
