ipn/localapi: add support for multipart POST to file-put

This allows sending multiple files via Taildrop in one request.
Progress is tracked via ipn.Notify.

Updates tailscale/corp#18202

Signed-off-by: Percy Wegmann <percy@tailscale.com>

cmd/tailscaled/depaware.txt

@@ -102,7 +102,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
    L    github.com/google/nftables/expr                              from github.com/google/nftables+
    L    github.com/google/nftables/internal/parseexprfunc            from github.com/google/nftables+
    L    github.com/google/nftables/xt                                from github.com/google/nftables/expr+
-        github.com/google/uuid                                       from tailscale.com/clientupdate
+        github.com/google/uuid                                       from tailscale.com/clientupdate+
         github.com/gorilla/csrf                                      from tailscale.com/client/web
         github.com/gorilla/securecookie                              from github.com/gorilla/csrf
         github.com/hdevalence/ed25519consensus                       from tailscale.com/clientupdate/distsign+
@@ -376,6 +376,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
    W 💣 tailscale.com/util/osdiag/internal/wsc                       from tailscale.com/util/osdiag
         tailscale.com/util/osshare                                   from tailscale.com/cmd/tailscaled+
         tailscale.com/util/osuser                                    from tailscale.com/ipn/localapi+
+        tailscale.com/util/progresstracking                          from tailscale.com/ipn/localapi
         tailscale.com/util/race                                      from tailscale.com/net/dns/resolver
         tailscale.com/util/racebuild                                 from tailscale.com/logpolicy
         tailscale.com/util/rands                                     from tailscale.com/ipn/ipnlocal+
@@ -522,7 +523,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         math/rand                                                    from github.com/mdlayher/netlink+
         math/rand/v2                                                 from tailscale.com/util/rands
         mime                                                         from github.com/tailscale/xnet/webdav+
-        mime/multipart                                               from net/http
+        mime/multipart                                               from net/http+
         mime/quotedprintable                                         from mime/multipart
         net                                                          from crypto/tls+
         net/http                                                     from expvar+

ipn/backend.go

@@ -202,8 +202,8 @@ type PartialFile struct {
 
 // OutgoingFile represents an in-progress outgoing file transfer.
 type OutgoingFile struct {
-	ID           string               `json:"-"` // unique identifier for this transfer (a type 4 UUID)
-	PeerID       tailcfg.StableNodeID // identifier for the peer to which this is being transferred
+	ID           string               `json:",omitempty"` // unique identifier for this transfer (a type 4 UUID)
+	PeerID       tailcfg.StableNodeID `json:",omitempty"` // identifier for the peer to which this is being transferred
 	Name         string               `json:",omitempty"` // e.g. "foo.jpg"
 	Started      time.Time            // time transfer started
 	DeclaredSize int64                // or -1 if unknown

ipn/ipnlocal/local.go

@@ -320,7 +320,7 @@ type LocalBackend struct {
 	// notified about.
 	lastNotifiedTailFSShares atomic.Pointer[views.SliceView[*tailfs.Share, tailfs.ShareView]]
 
-	// outgoingFiles keeps track of Taildrop outgoing files
+	// outgoingFiles keeps track of Taildrop outgoing files keyed to their OutgoingFile.ID
 	outgoingFiles map[string]*ipn.OutgoingFile
 }
 

ipn/ipnlocal/taildrop.go

@@ -4,20 +4,21 @@
 package ipnlocal
 
 import (
+	"maps"
 	"slices"
 	"strings"
 
 	"tailscale.com/ipn"
 )
 
-func (b *LocalBackend) UpdateOutgoingFiles(updates map[string]ipn.OutgoingFile) {
+// UpdateOutgoingFiles updates b.outgoingFiles to reflect the given updates and
+// sends an ipn.Notify with the full list of outgoingFiles.
+func (b *LocalBackend) UpdateOutgoingFiles(updates map[string]*ipn.OutgoingFile) {
 	b.mu.Lock()
 	if b.outgoingFiles == nil {
 		b.outgoingFiles = make(map[string]*ipn.OutgoingFile, len(updates))
 	}
-	for id, file := range updates {
-		b.outgoingFiles[id] = &file
-	}
+	maps.Copy(b.outgoingFiles, updates)
 	outgoingFiles := make([]*ipn.OutgoingFile, 0, len(b.outgoingFiles))
 	for _, file := range b.outgoingFiles {
 		outgoingFiles = append(outgoingFiles, file)

ipn/localapi/localapi.go

@@ -1535,11 +1535,10 @@ func (h *Handler) serveFileTargets(w http.ResponseWriter, r *http.Request) {
 // directly, as the Windows GUI always runs in tun mode anyway.
 //
 // In addition to single file PUTs, this endpoint accepts multipart file
-// POSTS encoded as multipart/form-data. Each part must include a
-// "Content-Length" in the MIME header indicating the size of the file.
-// The first part should be an application/json file that contains a JSON map
-// of filename -> length, which we can use for tracking progress even before
-// reading the file parts.
+// POSTS encoded as multipart/form-data.The first part should be an
+// application/json file that contains a manifest consisting of a JSON array of
+// OutgoingFiles which wecan use for tracking progress even before reading the
+// file parts.
 //
 // URL format:
 //
@@ -1599,9 +1598,9 @@ func (h *Handler) serveFilePut(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Report progress on outgoing files every 5 seconds
-	outgoingFiles := make(map[string]ipn.OutgoingFile)
-	t := time.NewTicker(5 * time.Second)
+	// Periodically report progress of outgoing files.
+	outgoingFiles := make(map[string]*ipn.OutgoingFile)
+	t := time.NewTicker(1 * time.Second)
 	progressUpdates := make(chan ipn.OutgoingFile)
 	defer close(progressUpdates)
 
@@ -1614,7 +1613,7 @@ func (h *Handler) serveFilePut(w http.ResponseWriter, r *http.Request) {
 				if !ok {
 					return
 				}
-				outgoingFiles[u.ID] = u
+				outgoingFiles[u.ID] = &u
 			case <-t.C:
 				h.b.UpdateOutgoingFiles(outgoingFiles)
 			}
@@ -1672,21 +1671,15 @@ func (h *Handler) multiFilePost(progressUpdates chan (ipn.OutgoingFile), w http.
 				return
 			}
 
-			var manifest map[string]int64
+			var manifest []ipn.OutgoingFile
 			err := json.NewDecoder(part).Decode(&manifest)
 			if err != nil {
 				http.Error(ww, fmt.Sprintf("invalid manifest: %s", err), http.StatusBadRequest)
 				return
 			}
 
-			for filename, size := range manifest {
-				file := ipn.OutgoingFile{
-					ID:           uuid.Must(uuid.NewRandom()).String(),
-					Name:         filename,
-					PeerID:       peerID,
-					DeclaredSize: size,
-				}
-				outgoingFilesByName[filename] = file
+			for _, file := range manifest {
+				outgoingFilesByName[file.Name] = file
 				progressUpdates <- file
 			}