Crate oauth2

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An extensible, strongly-typed implementation of OAuth2 (RFC 6749) including token introspection (RFC 7662) and token revocation (RFC 7009).

§Contents

§Importing oauth2: selecting an HTTP client interface

This library offers a flexible HTTP client interface with two modes:

  • Synchronous (blocking)

    NOTE: Be careful not to use a blocking HTTP client within async Rust code, which may panic or cause other issues. The tokio::task::spawn_blocking function may be useful in this situation.

  • Asynchronous

§Security Warning

To prevent SSRF vulnerabilities, be sure to configure the HTTP client not to follow redirects. For example, use redirect::Policy::none when using reqwest, or redirects(0) when using [ureq].

§HTTP Clients

For the HTTP client modes described above, the following HTTP client implementations can be used:

  • reqwest

    The reqwest HTTP client supports both the synchronous and asynchronous modes and is enabled by default.

    Synchronous client: [reqwest::blocking::Client] (requires the reqwest-blocking feature flag)

    Asynchronous client: reqwest::Client (requires either the reqwest or reqwest-blocking feature flags)

  • curl

    The curl HTTP client only supports the synchronous HTTP client mode and can be enabled in Cargo.toml via the curl feature flag.

    Synchronous client: oauth2::CurlHttpClient

  • ureq

    The ureq HTTP client is a simple HTTP client with minimal dependencies. It only supports the synchronous HTTP client mode and can be enabled in Cargo.toml via the ureq feature flag.

    Synchronous client: [ureq::Agent]

  • Custom

    In addition to the clients above, users may define their own HTTP clients, which must accept an HttpRequest and return an HttpResponse or error. Users writing their own clients may wish to disable the default reqwest dependency by specifying default-features = false in Cargo.toml (replacing ... with the desired version of this crate):

    oauth2 = { version = "...", default-features = false }

    Synchronous HTTP clients should implement the SyncHttpClient trait, which is automatically implemented for any function/closure that implements:

    ⓘ
    Fn(HttpRequest) -> Result<HttpResponse, E>
where
  E: std::error::Error + 'static

    Asynchronous HTTP clients should implement the AsyncHttpClient trait, which is automatically implemented for any function/closure that implements:

    ⓘ
    Fn(HttpRequest) -> F
where
  E: std::error::Error + 'static,
  F: Future<Output = Result<HttpResponse, E>>,

§Comparing secrets securely

OAuth flows require comparing secrets received from the provider servers. To do so securely while avoiding timing side-channels, the comparison must be done in constant time, either using a constant-time crate such as constant_time_eq (which could break if a future compiler version decides to be overly smart about its optimizations), or by first computing a cryptographically-secure hash (e.g., SHA-256) of both values and then comparing the hashes using ==.

The timing-resistant-secret-traits feature flag adds a safe (but comparatively expensive) PartialEq implementation to the secret types. Timing side-channels are why PartialEq is not auto-derived for this crate’s secret types, and the lack of PartialEq is intended to prompt users to think more carefully about these comparisons.

§Getting started: Authorization Code Grant w/ PKCE

This is the most common OAuth2 flow. PKCE is recommended whenever the OAuth2 client has no client secret or has a client secret that cannot remain confidential (e.g., native, mobile, or client-side web applications).

§Example: Synchronous (blocking) API

This example works with oauth2’s default feature flags, which include reqwest.

use oauth2::{
    AuthorizationCode,
    AuthUrl,
    ClientId,
    ClientSecret,
    CsrfToken,
    PkceCodeChallenge,
    RedirectUrl,
    Scope,
    TokenResponse,
    TokenUrl
};
use oauth2::basic::BasicClient;
use oauth2::reqwest;
use url::Url;

// Create an OAuth2 client by specifying the client ID, client secret, authorization URL and
// token URL.
let client = BasicClient::new(ClientId::new("client_id".to_string()))
    .set_client_secret(ClientSecret::new("client_secret".to_string()))
    .set_auth_uri(AuthUrl::new("http://authorize".to_string())?)
    .set_token_uri(TokenUrl::new("http://token".to_string())?)
    // Set the URL the user will be redirected to after the authorization process.
    .set_redirect_uri(RedirectUrl::new("http://redirect".to_string())?);

// Generate a PKCE challenge.
let (pkce_challenge, pkce_verifier) = PkceCodeChallenge::new_random_sha256();

// Generate the full authorization URL.
let (auth_url, csrf_token) = client
    .authorize_url(CsrfToken::new_random)
    // Set the desired scopes.
    .add_scope(Scope::new("read".to_string()))
    .add_scope(Scope::new("write".to_string()))
    // Set the PKCE code challenge.
    .set_pkce_challenge(pkce_challenge)
    .url();

// This is the URL you should redirect the user to, in order to trigger the authorization
// process.
println!("Browse to: {}", auth_url);

// Once the user has been redirected to the redirect URL, you'll have access to the
// authorization code. For security reasons, your code should verify that the `state`
// parameter returned by the server matches `csrf_token`.

let http_client = reqwest::blocking::ClientBuilder::new()
    // Following redirects opens the client up to SSRF vulnerabilities.
    .redirect(reqwest::redirect::Policy::none())
    .build()
    .expect("Client should build");

// Now you can trade it for an access token.
let token_result =
    client
        .exchange_code(AuthorizationCode::new("some authorization code".to_string()))
        // Set the PKCE code verifier.
        .set_pkce_verifier(pkce_verifier)
        .request(&http_client)?;

// Unwrapping token_result will either produce a Token or a RequestTokenError.

§Example: Asynchronous API

The example below uses async/await:

use oauth2::{
    AuthorizationCode,
    AuthUrl,
    ClientId,
    ClientSecret,
    CsrfToken,
    PkceCodeChallenge,
    RedirectUrl,
    Scope,
    TokenResponse,
    TokenUrl
};
use oauth2::basic::BasicClient;
use oauth2::reqwest;
use url::Url;

// Create an OAuth2 client by specifying the client ID, client secret, authorization URL and
// token URL.
let client = BasicClient::new(ClientId::new("client_id".to_string()))
    .set_client_secret(ClientSecret::new("client_secret".to_string()))
    .set_auth_uri(AuthUrl::new("http://authorize".to_string())?)
    .set_token_uri(TokenUrl::new("http://token".to_string())?)
    // Set the URL the user will be redirected to after the authorization process.
    .set_redirect_uri(RedirectUrl::new("http://redirect".to_string())?);

// Generate a PKCE challenge.
let (pkce_challenge, pkce_verifier) = PkceCodeChallenge::new_random_sha256();

// Generate the full authorization URL.
let (auth_url, csrf_token) = client
    .authorize_url(CsrfToken::new_random)
    // Set the desired scopes.
    .add_scope(Scope::new("read".to_string()))
    .add_scope(Scope::new("write".to_string()))
    // Set the PKCE code challenge.
    .set_pkce_challenge(pkce_challenge)
    .url();

// This is the URL you should redirect the user to, in order to trigger the authorization
// process.
println!("Browse to: {}", auth_url);

// Once the user has been redirected to the redirect URL, you'll have access to the
// authorization code. For security reasons, your code should verify that the `state`
// parameter returned by the server matches `csrf_token`.

let http_client = reqwest::ClientBuilder::new()
    // Following redirects opens the client up to SSRF vulnerabilities.
    .redirect(reqwest::redirect::Policy::none())
    .build()
    .expect("Client should build");

// Now you can trade it for an access token.
let token_result = client
    .exchange_code(AuthorizationCode::new("some authorization code".to_string()))
    // Set the PKCE code verifier.
    .set_pkce_verifier(pkce_verifier)
    .request_async(&http_client)
    .await?;

// Unwrapping token_result will either produce a Token or a RequestTokenError.

§Implicit Grant

This flow fetches an access token directly from the authorization endpoint. Be sure to understand the security implications of this flow before using it. In most cases, the Authorization Code Grant flow is preferable to the Implicit Grant flow.

§Example

use oauth2::{
    AuthUrl,
    ClientId,
    CsrfToken,
    RedirectUrl,
    Scope
};
use oauth2::basic::BasicClient;
use url::Url;

let client = BasicClient::new(ClientId::new("client_id".to_string()))
    .set_auth_uri(AuthUrl::new("http://authorize".to_string())?);

// Generate the full authorization URL.
let (auth_url, csrf_token) = client
    .authorize_url(CsrfToken::new_random)
    .use_implicit_flow()
    .url();

// This is the URL you should redirect the user to, in order to trigger the authorization
// process.
println!("Browse to: {}", auth_url);

// Once the user has been redirected to the redirect URL, you'll have the access code.
// For security reasons, your code should verify that the `state` parameter returned by the
// server matches `csrf_token`.

§Resource Owner Password Credentials Grant

You can ask for a password access token by calling the Client::exchange_password method, while including the username and password.

§Example

use oauth2::{
    AuthUrl,
    ClientId,
    ClientSecret,
    ResourceOwnerPassword,
    ResourceOwnerUsername,
    Scope,
    TokenResponse,
    TokenUrl
};
use oauth2::basic::BasicClient;
use oauth2::reqwest;
use url::Url;

let client = BasicClient::new(ClientId::new("client_id".to_string()))
    .set_client_secret(ClientSecret::new("client_secret".to_string()))
    .set_auth_uri(AuthUrl::new("http://authorize".to_string())?)
    .set_token_uri(TokenUrl::new("http://token".to_string())?);

let http_client = reqwest::blocking::ClientBuilder::new()
    // Following redirects opens the client up to SSRF vulnerabilities.
    .redirect(reqwest::redirect::Policy::none())
    .build()
    .expect("Client should build");

let token_result =
    client
        .exchange_password(
            &ResourceOwnerUsername::new("user".to_string()),
            &ResourceOwnerPassword::new("pass".to_string())
        )
        .add_scope(Scope::new("read".to_string()))
        .request(&http_client)?;

§Client Credentials Grant

You can ask for a client credentials access token by calling the Client::exchange_client_credentials method.

§Example

use oauth2::{
    AuthUrl,
    ClientId,
    ClientSecret,
    Scope,
    TokenResponse,
    TokenUrl
};
use oauth2::basic::BasicClient;
use oauth2::reqwest;
use url::Url;

let client = BasicClient::new(ClientId::new("client_id".to_string()))
    .set_client_secret(ClientSecret::new("client_secret".to_string()))
    .set_auth_uri(AuthUrl::new("http://authorize".to_string())?)
    .set_token_uri(TokenUrl::new("http://token".to_string())?);

let http_client = reqwest::blocking::ClientBuilder::new()
    // Following redirects opens the client up to SSRF vulnerabilities.
    .redirect(reqwest::redirect::Policy::none())
    .build()
    .expect("Client should build");

let token_result = client
    .exchange_client_credentials()
    .add_scope(Scope::new("read".to_string()))
    .request(&http_client)?;

§Device Authorization Flow

Device Authorization Flow allows users to sign in on browserless or input-constrained devices. This is a two-stage process; first a user-code and verification URL are obtained by using the Client::exchange_client_credentials method. Those are displayed to the user, then are used in a second client to poll the token endpoint for a token.

§Example

use oauth2::{
    AuthUrl,
    ClientId,
    ClientSecret,
    DeviceAuthorizationUrl,
    Scope,
    StandardDeviceAuthorizationResponse,
    TokenResponse,
    TokenUrl
};
use oauth2::basic::BasicClient;
use oauth2::reqwest;
use url::Url;

let device_auth_url = DeviceAuthorizationUrl::new("http://deviceauth".to_string())?;
let client = BasicClient::new(ClientId::new("client_id".to_string()))
    .set_client_secret(ClientSecret::new("client_secret".to_string()))
    .set_auth_uri(AuthUrl::new("http://authorize".to_string())?)
    .set_token_uri(TokenUrl::new("http://token".to_string())?)
    .set_device_authorization_url(device_auth_url);

let http_client = reqwest::blocking::ClientBuilder::new()
    // Following redirects opens the client up to SSRF vulnerabilities.
    .redirect(reqwest::redirect::Policy::none())
    .build()
    .expect("Client should build");

let details: StandardDeviceAuthorizationResponse = client
    .exchange_device_code()
    .add_scope(Scope::new("read".to_string()))
    .request(&http_client)?;

println!(
    "Open this URL in your browser:\n{}\nand enter the code: {}",
    details.verification_uri().to_string(),
    details.user_code().secret().to_string()
);

let token_result =
    client
    .exchange_device_access_token(&details)
    .request(&http_client, std::thread::sleep, None)?;

§Other examples

More specific implementations are available as part of the examples:

§Contributed Examples

Re-exports§

Modules§

  • basic
    Basic OAuth2 implementation with no extensions (RFC 6749).
  • helpers
    Helper methods used by OAuth2 implementations/extensions.

Structs§

Enums§

Traits§

Type Aliases§