Add a PUT handler for the local bucket server.

cli/daemon/objects/public.go

@@ -1,12 +1,18 @@
 package objects
 
 import (
+	"errors"
+	"fmt"
+	"io"
 	"net"
 	"net/http"
 	"strconv"
+	"strings"
 	"sync"
+	"time"
 
 	"encr.dev/pkg/emulators/storage/gcsemu"
+	"google.golang.org/api/storage/v1"
 )
 
 // Fallback is a function that returns a store for a given namespace.
@@ -77,22 +83,107 @@ func (s *PublicBucketServer) handler(w http.ResponseWriter, req *http.Request) {
 		http.Error(w, "unknown namespace", http.StatusNotFound)
 		return
 	}
+	switch req.Method {
+	case "GET":
+		obj, contents, err := store.Get("", bucketName, objName)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		} else if obj == nil {
+			http.Error(w, "object not found", http.StatusNotFound)
+			return
+		}
 
-	obj, contents, err := store.Get("", bucketName, objName)
+		if obj.ContentType != "" {
+			w.Header().Set("Content-Type", obj.ContentType)
+		}
+		if obj.Etag != "" {
+			w.Header().Set("Etag", obj.Etag)
+		}
+		w.Header().Set("Content-Length", strconv.Itoa(len(contents)))
+		w.Write(contents)
+	case "PUT":
+		// Only signed URLs are supported for PUT.
+		err := validateSignedUpload(req, time.Now())
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		buf, err := io.ReadAll(req.Body)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		metaIn := parseObjectMeta(req)
+		err = store.Add(bucketName, objName, buf, &metaIn)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		// Read back the object so we can add the etag value to the response.
+		metaOut, _, err := store.Get("", bucketName, objName)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		w.Header().Set("Etag", metaOut.Etag)
+	default:
+		http.Error(w, "method not allowed", http.StatusBadRequest)
+	}
+}
+
+func validateSignedUpload(req *http.Request, now time.Time) error {
+	const dateLayout = "20060102T150405Z"
+	const gracePeriod = time.Duration(30) * time.Second
+
+	query := map[string]string{}
+	for k, vs := range req.URL.Query() {
+		query[strings.ToLower(k)] = vs[0]
+	}
+
+	// We don't try to actually verify the signature, we only check that it's non-empty.
+
+	// This URL parsing is specific to GCS URLs. OTOH, we would like this
+	// bucket server to look as generic as possible to apps running locally.
+	// To avoid apps accidentally implementing provider specific behaviour
+	// that fails if deployed on a different cloud in prod. It might seem like
+	// the "x-goog-" fields below contradicts this. However: 1) the upload URLs
+	// are (supposed to be) opaque to clients, and 2) we always use the GCS URL
+	// signer in local mode.
+	for _, s := range []string{
+		"x-goog-signature",
+		"x-goog-credential",
+		"x-goog-date",
+		"x-goog-expires"} {
+		if len(query[s]) <= 0 {
+			return fmt.Errorf("missing or empty query param %q", s)
+		}
+	}
+
+	t0, err := time.Parse(dateLayout, query["x-goog-date"])
 	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	} else if obj == nil {
-		http.Error(w, "object not found", http.StatusNotFound)
-		return
+		return errors.New("failed to parse x-goog-date")
+	}
+	if t0.After(now.Add(gracePeriod)) {
+		return errors.New("URL expiration base date is in the future")
 	}
 
-	if obj.ContentType != "" {
-		w.Header().Set("Content-Type", obj.ContentType)
+	td, err := strconv.Atoi(query["x-goog-expires"])
+	if err != nil {
+		return errors.New("failed to parse x-goog-expires value into an integer")
 	}
-	if obj.Etag != "" {
-		w.Header().Set("Etag", obj.Etag)
+	t := t0.Add(time.Duration(td) * time.Second)
+
+	if t.Before(now.Add(-gracePeriod)) {
+		return errors.New("URL is expired")
 	}
-	w.Header().Set("Content-Length", strconv.Itoa(len(contents)))
-	w.Write(contents)
+
+	return nil
+}
+
+func parseObjectMeta(req *http.Request) storage.Object {
+	return storage.Object{ContentType: req.Header.Get("Content-Type")}
 }