95 lines
3.0 KiB
Go
95 lines
3.0 KiB
Go
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// Package auth implements §8 of design.md: Authentik OIDC discovery + JWKS
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// caching, and JWT validation shared by the gRPC and REST (grpc-gateway)
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// transports via a single interceptor.
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package auth
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import (
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"strings"
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"time"
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"github.com/lestrrat-go/jwx/v2/jwk"
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)
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// DiscoveryDocument is the subset of an OIDC discovery document this package
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// needs.
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type DiscoveryDocument struct {
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Issuer string `json:"issuer"`
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JWKSURI string `json:"jwks_uri"`
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}
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// FetchDiscoveryDocument GETs issuerURL's well-known OIDC discovery document.
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func FetchDiscoveryDocument(ctx context.Context, issuerURL string) (*DiscoveryDocument, error) {
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url := strings.TrimRight(issuerURL, "/") + "/.well-known/openid-configuration"
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
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if err != nil {
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return nil, fmt.Errorf("build discovery request: %w", err)
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}
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resp, err := http.DefaultClient.Do(req)
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if err != nil {
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return nil, fmt.Errorf("fetch discovery document %s: %w", url, err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("fetch discovery document %s: status %d", url, resp.StatusCode)
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}
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var doc DiscoveryDocument
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if err := json.NewDecoder(resp.Body).Decode(&doc); err != nil {
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return nil, fmt.Errorf("decode discovery document %s: %w", url, err)
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}
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return &doc, nil
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}
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// KeySetProvider returns the current JWKS for validating a token's
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// signature. Abstracted so tests can inject a static key set instead of
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// running a real JWKS HTTP endpoint.
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type KeySetProvider interface {
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Get(ctx context.Context) (jwk.Set, error)
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}
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// JWKSCache fetches a JWKS URI once at startup and keeps it fresh via a
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// background auto-refresh, so request-path validation never makes a network
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// call (design.md §8).
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type JWKSCache struct {
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jwksURI string
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cache *jwk.Cache
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}
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// NewJWKSCache registers jwksURI with a background auto-refreshing cache and
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// performs the initial fetch synchronously so startup fails fast on a
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// misconfigured/unreachable JWKS endpoint.
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func NewJWKSCache(ctx context.Context, jwksURI string) (*JWKSCache, error) {
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cache := jwk.NewCache(ctx)
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if err := cache.Register(jwksURI, jwk.WithMinRefreshInterval(15*time.Minute)); err != nil {
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return nil, fmt.Errorf("register jwks cache %s: %w", jwksURI, err)
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}
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if _, err := cache.Refresh(ctx, jwksURI); err != nil {
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return nil, fmt.Errorf("initial jwks fetch %s: %w", jwksURI, err)
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}
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return &JWKSCache{jwksURI: jwksURI, cache: cache}, nil
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}
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// Get returns the cached key set, refreshing in the background per the
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// interval configured in NewJWKSCache rather than on every call.
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func (c *JWKSCache) Get(ctx context.Context) (jwk.Set, error) {
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return c.cache.Get(ctx, c.jwksURI)
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}
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// staticKeySet is a KeySetProvider backed by a fixed jwk.Set, used in tests
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// to avoid standing up a real JWKS HTTP endpoint.
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type staticKeySet struct {
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set jwk.Set
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}
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func StaticKeySet(set jwk.Set) KeySetProvider {
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return staticKeySet{set: set}
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}
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func (s staticKeySet) Get(ctx context.Context) (jwk.Set, error) {
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return s.set, nil
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}
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