oauth

package
v0.2.12 Latest Latest
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 Go to latest Published: Jun 20, 2026 License: Apache-2.0 Imports: 20 Imported by: 0

Documentation

Overview

Package oauth provides OAuth 2.0 authentication for remote MCP servers. It implements browser-based authorization code flow with PKCE, token storage, server probing, and OAuth metadata discovery.

Index

Constants

View Source 
const (
	// DefaultClientIDMetadataURL is the CIMD URL hosted on GitHub Pages.
	// Authorization servers that support Client ID Metadata Documents (CIMD)
	// will fetch this URL to validate client metadata (redirect URIs, etc.).
	DefaultClientIDMetadataURL = "https://giantswarm.github.io/klausctl/client.json"
)

Variables

This section is empty.

Functions

func ClearMetadataCache 

func ClearMetadataCache()

ClearMetadataCache removes all cached metadata entries. Exported for testing.

func OpenBrowser 

func OpenBrowser(rawURL string) error

OpenBrowser opens the given URL in the user's default browser. Only http and https schemes are allowed.

Types

type AuthChallenge 

type AuthChallenge struct {
	Realm            string
	ResourceMetadata string
}

AuthChallenge represents parsed fields from a WWW-Authenticate: Bearer response header.

func ParseWWWAuthenticate 

func ParseWWWAuthenticate(header string) *AuthChallenge

ParseWWWAuthenticate extracts realm and resource_metadata from a WWW-Authenticate: Bearer response header value. It handles both quoted and unquoted parameter values, and is tolerant of extra whitespace.

Examples of supported formats: 

Bearer realm="https://dex.example.com"
Bearer realm="https://dex.example.com", resource_metadata="https://mcp.example.com/.well-known/oauth-protected-resource"
Bearer realm="https://dex.example.com",resource_metadata="https://mcp.example.com/.well-known/oauth-protected-resource"

func ProbeServer 

func ProbeServer(ctx context.Context, serverURL string) (*AuthChallenge, error)

ProbeServer sends a HEAD request to the given MCP server URL and checks for a 401 Unauthorized response with a WWW-Authenticate: Bearer header. Returns nil if the server does not require authentication. Falls back to checking .well-known/oauth-protected-resource (RFC 9728) when the HEAD response lacks a WWW-Authenticate header.

type CallbackResult 

type CallbackResult struct {
	Code  string
	State string
	Error string
}

CallbackResult holds the authorization code or error received from the OAuth callback.

type CallbackServer 

type CallbackServer struct {
	// contains filtered or unexported fields
}

CallbackServer listens on 127.0.0.1:3001 for a single OAuth callback, then shuts down automatically.

func NewCallbackServer 

func NewCallbackServer(expectedState string) *CallbackServer

NewCallbackServer creates a callback server that validates the state parameter against expectedState.

func (*CallbackServer) Start 

func (cs *CallbackServer) Start() (string, error)

Start begins listening for the OAuth callback. Returns the full callback URL that should be registered as the redirect_uri.

func (*CallbackServer) WaitForCallback 

func (cs *CallbackServer) WaitForCallback(ctx context.Context) (CallbackResult, error)

WaitForCallback blocks until the OAuth callback is received or the context is cancelled. Shuts down the server before returning.

type Client 

type Client struct {
	// contains filtered or unexported fields
}

Client orchestrates the full OAuth authorization code flow with PKCE.

func NewClient 

func NewClient(store *TokenStore) *Client

NewClient creates a Client backed by the given TokenStore.

func (*Client) AuthStatus 

func (c *Client) AuthStatus(serverURL string) TokenStatus

AuthStatus returns the token status for the given server URL.

func (*Client) Login 

func (c *Client) Login(ctx context.Context, serverURL string) error

Login performs browser-based OAuth login for the given MCP server URL. It probes the server, discovers OAuth metadata, starts a local callback server, opens the browser for user authentication, exchanges the authorization code, and stores the resulting token.

func (*Client) Logout 

func (c *Client) Logout(serverURL string) error

Logout removes the stored token for the given server URL.

type Metadata 

type Metadata struct {
	Issuer                 string   `json:"issuer"`
	AuthorizationEndpoint  string   `json:"authorization_endpoint"`
	TokenEndpoint          string   `json:"token_endpoint"`
	ScopesSupported        []string `json:"scopes_supported,omitempty"`
	CodeChallengeSupported []string `json:"code_challenge_methods_supported,omitempty"`
}

Metadata holds OAuth authorization server metadata from RFC 8414 (.well-known/oauth-authorization-server) or OpenID Connect discovery (.well-known/openid-configuration).

func DiscoverMetadata 

func DiscoverMetadata(ctx context.Context, issuerURL string) (*Metadata, error)

DiscoverMetadata fetches OAuth authorization server metadata from the issuer URL. It tries RFC 8414 (.well-known/oauth-authorization-server) first, then falls back to OpenID Connect discovery (.well-known/openid-configuration). Results are cached with a 10-minute TTL.

type PKCEChallenge 

type PKCEChallenge struct {
	Verifier        string
	Challenge       string
	ChallengeMethod string
}

PKCEChallenge holds a PKCE verifier/challenge pair for the S256 method.

func GeneratePKCE 

func GeneratePKCE() PKCEChallenge

GeneratePKCE creates a new PKCE verifier/challenge pair using the S256 method. Uses golang.org/x/oauth2's cryptographically secure implementation.

type ProtectedResourceMetadata 

type ProtectedResourceMetadata struct {
	Resource             string   `json:"resource"`
	AuthorizationServers []string `json:"authorization_servers"`
	BearerMethods        []string `json:"bearer_methods_supported,omitempty"`
}

ProtectedResourceMetadata holds RFC 9728 OAuth Protected Resource Metadata fetched from .well-known/oauth-protected-resource.

func FetchResourceMetadata 

func FetchResourceMetadata(ctx context.Context, metadataURL string) (*ProtectedResourceMetadata, error)

FetchResourceMetadata fetches RFC 9728 OAuth Protected Resource Metadata from the given URL. This is used when a server's WWW-Authenticate header contains resource_metadata instead of realm.

type StoredToken 

type StoredToken struct {
	Token     Token     `json:"token"`
	Issuer    string    `json:"issuer"`
	ServerURL string    `json:"server_url"`
	CreatedAt time.Time `json:"created_at"`
}

StoredToken wraps a Token with metadata needed for storage and refresh.

func (*StoredToken) IsExpired 

func (st *StoredToken) IsExpired() bool

IsExpired reports whether the access token has expired based on the stored creation time and expires_in value. Returns false when no expiry information is available (treat as non-expiring).

type Token 

type Token struct {
	AccessToken  string `json:"access_token"`
	TokenType    string `json:"token_type"`
	RefreshToken string `json:"refresh_token,omitempty"`
	ExpiresIn    int    `json:"expires_in,omitempty"`
}

Token holds the raw OAuth token fields returned by the authorization server.

type TokenStatus 

type TokenStatus struct {
	ServerURL string
	Issuer    string
	Status    string // "valid", "expired", "none"
	ExpiresAt string // RFC3339 or empty
}

TokenStatus describes the authentication state for a server.

type TokenStore 

type TokenStore struct {
	// contains filtered or unexported fields
}

TokenStore manages OAuth tokens persisted as JSON files keyed by server URL. Each server gets a file at <dir>/<url-safe-hash>.json with 0600 permissions.

func NewTokenStore 

func NewTokenStore(dir string) *TokenStore

NewTokenStore creates a TokenStore backed by the given directory. The directory is created on first write if it does not exist.

func (*TokenStore) DeleteToken 

func (s *TokenStore) DeleteToken(serverURL string) error

DeleteToken removes the stored token for the given server URL.

func (*TokenStore) GetToken 

func (s *TokenStore) GetToken(serverURL string) *StoredToken

GetToken retrieves the stored token for the given server URL. Returns nil if no token is stored.

func (*TokenStore) GetValidToken 

func (s *TokenStore) GetValidToken(serverURL string) *StoredToken

GetValidToken retrieves a non-expired token for the server URL. Returns nil if no token is stored or the token has expired.

func (*TokenStore) HasValidToken 

func (s *TokenStore) HasValidToken(serverURL string) bool

HasValidToken reports whether a non-expired token exists for the server.

func (*TokenStore) ListTokens 

func (s *TokenStore) ListTokens() ([]TokenStatus, error)

ListTokens returns the status of all stored tokens sorted by server URL.

func (*TokenStore) StoreToken 

func (s *TokenStore) StoreToken(serverURL, issuerURL string, token Token) error

StoreToken persists a token for the given server and issuer URLs.

Source Files

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