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dex/vendor/github.com/coreos/go-oidc/jwks.go
2016-12-01 13:16:14 -08:00

200 lines
5.1 KiB
Go

package oidc
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"sync"
"time"
"github.com/pquerna/cachecontrol"
"golang.org/x/net/context"
"golang.org/x/net/context/ctxhttp"
jose "gopkg.in/square/go-jose.v2"
)
// keysExpiryDelta is the allowed clock skew between a client and the OpenID Connect
// server.
//
// When keys expire, they are valid for this amount of time after.
//
// If the keys have not expired, and an ID Token claims it was signed by a key not in
// the cache, if and only if the keys expire in this amount of time, the keys will be
// updated.
const keysExpiryDelta = 30 * time.Second
func newRemoteKeySet(ctx context.Context, jwksURL string, now func() time.Time) *remoteKeySet {
if now == nil {
now = time.Now
}
return &remoteKeySet{jwksURL: jwksURL, ctx: ctx, now: now}
}
type remoteKeySet struct {
jwksURL string
ctx context.Context
now func() time.Time
// guard all other fields
mu sync.Mutex
// inflightCtx suppresses parallel execution of updateKeys and allows
// multiple goroutines to wait for its result.
// Its Err() method returns any errors encountered during updateKeys.
//
// If nil, there is no inflight updateKeys request.
inflightCtx *inflight
// A set of cached keys and their expiry.
cachedKeys []jose.JSONWebKey
expiry time.Time
}
// inflight is used to wait on some in-flight request from multiple goroutines
type inflight struct {
done chan struct{}
err error
}
// Done returns a channel that is closed when the inflight request finishes.
func (i *inflight) Done() <-chan struct{} {
return i.done
}
// Err returns any error encountered during request execution. May be nil.
func (i *inflight) Err() error {
return i.err
}
// Cancel signals completion of the inflight request with error err.
// Must be called only once for particular inflight instance.
func (i *inflight) Cancel(err error) {
i.err = err
close(i.done)
}
func (r *remoteKeySet) keysWithIDFromCache(keyIDs []string) ([]jose.JSONWebKey, bool) {
r.mu.Lock()
keys, expiry := r.cachedKeys, r.expiry
r.mu.Unlock()
// Have the keys expired?
if expiry.Add(keysExpiryDelta).Before(r.now()) {
return nil, false
}
var signingKeys []jose.JSONWebKey
for _, key := range keys {
if contains(keyIDs, key.KeyID) {
signingKeys = append(signingKeys, key)
}
}
if len(signingKeys) == 0 {
// Are the keys about to expire?
if r.now().Add(keysExpiryDelta).After(expiry) {
return nil, false
}
}
return signingKeys, true
}
func (r *remoteKeySet) keysWithID(ctx context.Context, keyIDs []string) ([]jose.JSONWebKey, error) {
keys, ok := r.keysWithIDFromCache(keyIDs)
if ok {
return keys, nil
}
var inflightCtx *inflight
func() {
r.mu.Lock()
defer r.mu.Unlock()
// If there's not a current inflight request, create one.
if r.inflightCtx == nil {
inflightCtx := &inflight{make(chan struct{}), nil}
r.inflightCtx = inflightCtx
go func() {
// TODO(ericchiang): Upstream Kubernetes request that we recover every time
// we spawn a goroutine, because panics in a goroutine will bring down the
// entire program. There's no way to recover from another goroutine's panic.
//
// Most users actually want to let the panic propagate and bring down the
// program because it implies some unrecoverable state.
//
// Add a context key to allow the recover behavior.
//
// See: https://github.com/coreos/go-oidc/issues/89
// Sync keys and close inflightCtx when that's done.
// Use the remoteKeySet's context instead of the requests context
// because a re-sync is unique to the keys set and will span multiple
// requests.
inflightCtx.Cancel(r.updateKeys(r.ctx))
r.mu.Lock()
defer r.mu.Unlock()
r.inflightCtx = nil
}()
}
inflightCtx = r.inflightCtx
}()
select {
case <-ctx.Done():
return nil, ctx.Err()
case <-inflightCtx.Done():
if err := inflightCtx.Err(); err != nil {
return nil, err
}
}
// Since we've just updated keys, we don't care about the cache miss.
keys, _ = r.keysWithIDFromCache(keyIDs)
return keys, nil
}
func (r *remoteKeySet) updateKeys(ctx context.Context) error {
req, err := http.NewRequest("GET", r.jwksURL, nil)
if err != nil {
return fmt.Errorf("oidc: can't create request: %v", err)
}
resp, err := ctxhttp.Do(ctx, clientFromContext(ctx), req)
if err != nil {
return fmt.Errorf("oidc: get keys failed %v", err)
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return fmt.Errorf("oidc: read response body: %v", err)
}
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("oidc: get keys failed: %s %s", resp.Status, body)
}
var keySet jose.JSONWebKeySet
if err := json.Unmarshal(body, &keySet); err != nil {
return fmt.Errorf("oidc: failed to decode keys: %v %s", err, body)
}
// If the server doesn't provide cache control headers, assume the
// keys expire immediately.
expiry := r.now()
_, e, err := cachecontrol.CachableResponse(req, resp, cachecontrol.Options{})
if err == nil && e.After(expiry) {
expiry = e
}
r.mu.Lock()
defer r.mu.Unlock()
r.cachedKeys = keySet.Keys
r.expiry = expiry
return nil
}