auth: publish passkey foundations preview

third_party/go-webauthn/metadata/providers/cached/provider.go

@@ -0,0 +1,146 @@
+package cached
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+
+	"github.com/go-webauthn/webauthn/metadata"
+)
+
+// New returns a new cached Provider given a set of functional [Option]'s. This provider will download a new version and
+// save it to the configured file path if it doesn't exist or if it's out of date by default.
+func New(opts ...Option) (provider metadata.Provider, err error) {
+	p := &Provider{
+		update: true,
+		uri:    metadata.ProductionMDSURL,
+	}
+
+	for _, opt := range opts {
+		if err = opt(p); err != nil {
+			return nil, err
+		}
+	}
+
+	if p.name == "" {
+		return nil, fmt.Errorf("provider configured without setting a path for the cached file blob")
+	}
+
+	if p.newup == nil {
+		p.newup = defaultNew
+	}
+
+	if p.decoder == nil {
+		if p.decoder, err = metadata.NewDecoder(metadata.WithIgnoreEntryParsingErrors()); err != nil {
+			return nil, err
+		}
+	}
+
+	if p.clock == nil {
+		p.clock = &metadata.RealClock{}
+	}
+
+	if err = p.init(); err != nil {
+		return nil, err
+	}
+
+	return p, nil
+}
+
+// Provider implements a [metadata.Provider] with a file-based cache.
+type Provider struct {
+	metadata.Provider
+
+	name    string
+	uri     string
+	update  bool
+	force   bool
+	clock   metadata.Clock
+	client  *http.Client
+	decoder *metadata.Decoder
+	newup   NewFunc
+}
+
+func (p *Provider) init() (err error) {
+	var (
+		f       *os.File
+		rc      io.ReadCloser
+		created bool
+		mds     *metadata.Metadata
+	)
+
+	if f, created, err = doOpenOrCreate(p.name); err != nil {
+		return err
+	}
+
+	defer f.Close()
+
+	if created || p.force {
+		if rc, err = p.get(); err != nil {
+			return err
+		}
+	} else {
+		if mds, err = p.parse(f); err != nil {
+			return err
+		}
+
+		if p.outdated(mds) {
+			if rc, err = p.get(); err != nil {
+				return err
+			}
+		}
+	}
+
+	if rc != nil {
+		if err = doTruncateCopyAndSeekStart(f, rc); err != nil {
+			return err
+		}
+
+		if mds, err = p.parse(f); err != nil {
+			return err
+		}
+	}
+
+	var provider metadata.Provider
+
+	if provider, err = p.newup(mds); err != nil {
+		return err
+	}
+
+	p.Provider = provider
+
+	return nil
+}
+
+func (p *Provider) parse(rc io.ReadCloser) (data *metadata.Metadata, err error) {
+	var payload *metadata.PayloadJSON
+
+	if payload, err = p.decoder.Decode(rc); err != nil {
+		return nil, err
+	}
+
+	if data, err = p.decoder.Parse(payload); err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}
+
+func (p *Provider) outdated(mds *metadata.Metadata) bool {
+	return p.update && p.clock.Now().After(mds.Parsed.NextUpdate)
+}
+
+func (p *Provider) get() (f io.ReadCloser, err error) {
+	if p.client == nil {
+		p.client = &http.Client{}
+	}
+
+	var res *http.Response
+
+	if res, err = p.client.Get(p.uri); err != nil {
+		return nil, err
+	}
+
+	return res.Body, nil
+}