use alibi_core::endpoint::EndpointResponse;
use alibi_core::session::SessionRequest;
use alibi_core::store::OAuthClient;
use alibi_core::{AuthContext, AuthResult, AuthSchema};
use serde_json::Value;
pub(super) struct Credentials {
pub(super) client_id: String,
pub(super) secret: String,
pub(super) pre_verified: bool,
pub(super) method: &'static str,
}
const AUTH_FIELDS: [&str; 3] = ["client_secret", "client_assertion", "client_assertion_type"];
pub(super) async fn extract<S: AuthSchema>(
body: &Value,
req: &impl SessionRequest,
ctx: &AuthContext<S>,
provider: &super::OAuthProviderPlugin,
endpoint: &str,
) -> AuthResult<Result<Credentials, EndpointResponse>> {
let audience = format!(
"{}{}/oauth2/{endpoint}",
ctx.config.base_url.trim_end_matches('/'),
ctx.config.base_path
);
extract_for_audience(body, req, ctx, provider, &audience).await
}
pub(super) async fn extract_for_audience<S: AuthSchema>(
body: &Value,
req: &impl SessionRequest,
ctx: &AuthContext<S>,
provider: &super::OAuthProviderPlugin,
audience: &str,
) -> AuthResult<Result<Credentials, EndpointResponse>> {
let body = match normalize(body, req) {
Ok(body) => body,
Err(description) => {
return Ok(Err(super::clients::status_protocol_error(
400,
"invalid_request",
&description,
)?));
}
};
if body.get("client_assertion").is_some() || body.get("client_assertion_type").is_some() {
return super::assertion::verify(&body, ctx, provider, audience).await;
}
from_normalized(&body, req)
}
fn normalize(body: &Value, req: &impl SessionRequest) -> Result<Value, String> {
let mut fields = serde_json::Map::new();
for field in std::iter::once("client_id").chain(AUTH_FIELDS) {
if let Some(value) = body.get(field) {
if value == "" {
continue;
}
if !value.is_string() {
return Err(format!("{field} must be a string"));
}
_ = fields.insert(field.into(), value.clone());
}
}
let request = req.physical_request();
if let Some(request) = request
&& request.header("content-type").is_some_and(|value| {
value
.to_ascii_lowercase()
.contains("application/x-www-form-urlencoded")
})
{
let params = url::form_urlencoded::parse(request.body.as_deref().unwrap_or_default())
.into_owned()
.collect::<Vec<_>>();
for field in std::iter::once("client_id").chain(AUTH_FIELDS) {
let values = params
.iter()
.filter(|(key, value)| key == field && !value.is_empty())
.map(|(_, value)| value)
.collect::<Vec<_>>();
if values.len() > 1 {
return Err(format!("{field} must not be repeated"));
}
if field == "client_id" {
_ = fields.remove(field);
}
if let Some(value) = values.first() {
_ = fields.insert(field.into(), Value::String((*value).clone()));
}
}
}
let header = request
.and_then(|request| request.header("authorization"))
.is_some_and(|value| !value.is_empty());
let secret = fields.contains_key("client_secret");
let assertion =
fields.contains_key("client_assertion") || fields.contains_key("client_assertion_type");
if (header && (secret || assertion)) || (secret && assertion) {
return Err("A request must use only one client authentication method".into());
}
let mut normalized = body.as_object().cloned().unwrap_or_default();
for field in std::iter::once("client_id").chain(AUTH_FIELDS) {
_ = normalized.remove(field);
}
normalized.extend(fields);
Ok(Value::Object(normalized))
}
fn from_normalized(
body: &Value,
req: &impl SessionRequest,
) -> AuthResult<Result<Credentials, EndpointResponse>> {
let mut client_id = body
.get("client_id")
.and_then(Value::as_str)
.unwrap_or_default()
.to_owned();
let mut secret = body
.get("client_secret")
.and_then(Value::as_str)
.unwrap_or_default()
.to_owned();
let method = if let Some(header) = req
.physical_request()
.and_then(|request| request.header("authorization"))
.filter(|header| !header.is_empty())
{
if header
.get(..5)
.is_some_and(|scheme| scheme.eq_ignore_ascii_case("Basic"))
&& header.as_bytes().get(5) == Some(&b' ')
{
let Some((id, value)) =
decode_basic(header.get(6..).unwrap_or_default().trim_start_matches(' '))
else {
return header_denial(
401,
"invalid_client",
"invalid authorization header format",
Some("Basic"),
);
};
client_id = id;
secret = value;
"client_secret_basic"
} else {
let Some(scheme) = authorization_scheme(header) else {
return header_denial(
400,
"invalid_request",
"Invalid authorization header format",
None,
);
};
return header_denial(
401,
"invalid_client",
"unsupported authorization scheme",
Some(scheme),
);
}
} else if secret.is_empty() {
"none"
} else {
"client_secret_post"
};
Ok(Ok(Credentials {
client_id,
secret,
pre_verified: false,
method,
}))
}
fn header_denial(
status: u16,
code: &str,
description: &str,
scheme: Option<&str>,
) -> AuthResult<Result<Credentials, EndpointResponse>> {
let response = super::clients::status_protocol_error(status, code, description)?;
Ok(Err(if let Some(scheme) = scheme {
response.with_header("WWW-Authenticate", scheme)
} else {
response
}))
}
fn authorization_scheme(header: &str) -> Option<&str> {
let end = header
.find(|c: char| !c.is_ascii_alphanumeric() && !"!#$%&'*+-.^_`|~".contains(c))
.unwrap_or(header.len());
let scheme = header.get(..end).filter(|scheme| !scheme.is_empty())?;
if header
.get(end..)?
.chars()
.next()
.is_some_and(|c| !c.is_whitespace() && c != '\u{feff}')
{
return None;
}
Some(scheme)
}
fn decode_basic(encoded: &str) -> Option<(String, String)> {
let alphabet = if encoded.contains('-') || encoded.contains('_') {
b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
} else {
b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
};
let mut buffer = 0_u32;
let mut bits = 0_u8;
let mut bytes = Vec::new();
for byte in encoded.bytes().take_while(|byte| *byte != b'=') {
let value = alphabet.iter().position(|candidate| *candidate == byte)?;
buffer = (buffer << 6) | u32::try_from(value).ok()?;
bits += 6;
if bits >= 8 {
bits -= 8;
bytes.push(u8::try_from((buffer >> bits) & 255).ok()?);
}
}
let decoded = String::from_utf8_lossy(&bytes);
let decoded = decoded.strip_prefix('\u{feff}').unwrap_or(&decoded);
let (id, secret) = decoded.split_once(':')?;
if id.is_empty() || secret.is_empty() {
return None;
}
Some((decode_form_value(id)?, decode_form_value(secret)?))
}
fn decode_form_value(raw: &str) -> Option<String> {
url::form_urlencoded::parse(format!("v={raw}").as_bytes())
.next()
.map(|(_, value)| value.into_owned())
}
impl Credentials {
fn denied(&self, description: &str) -> AuthResult<EndpointResponse> {
let response = super::clients::status_protocol_error(
if self.method == "client_secret_basic" {
401
} else {
400
},
"invalid_client",
description,
)?;
Ok(if self.method == "client_secret_basic" {
response.with_header("WWW-Authenticate", "Basic")
} else {
response
})
}
pub(super) async fn authenticate<S: AuthSchema>(
&self,
ctx: &AuthContext<S>,
provider: &super::OAuthProviderPlugin,
) -> AuthResult<Result<OAuthClient, EndpointResponse>> {
let config = &provider.config;
let Some(client) = provider.get_client(ctx, &self.client_id).await? else {
return Ok(Err(self.denied("missing client")?));
};
if client.metadata.get("disabled") == Some(&Value::Bool(true)) {
return Ok(Err(self.denied("client is disabled")?));
}
let registered = client
.metadata
.get("token_endpoint_auth_method")
.and_then(Value::as_str)
.unwrap_or("client_secret_basic");
if registered != self.method {
return Ok(Err(self.denied(&format!(
"client registered for {registered} cannot use {}",
self.method
))?));
}
if !self.pre_verified && registered != "none" && self.secret.is_empty() {
return Ok(Err(self.denied("client secret must be provided")?));
}
if !self.secret.is_empty() && client.client_secret.is_none() {
return Ok(Err(
self.denied("public client, client secret should not be received")?
));
}
if !self.secret.is_empty() {
let secret = if let Some(prefix) = config
.client_secret_prefix
.as_deref()
.filter(|prefix| !prefix.is_empty())
{
let Some(secret) = self.secret.strip_prefix(prefix) else {
return Ok(Err(super::clients::status_protocol_error(
401,
"invalid_client",
"invalid client_secret",
)?));
};
secret
} else {
self.secret.as_str()
};
let valid = if let Some(stored) = client.client_secret.as_deref() {
super::client_secret::verify(ctx, config, secret, stored).await?
} else {
false
};
if !valid {
return Ok(Err(self.denied("invalid client_secret")?));
}
}
Ok(Ok(client))
}
}