try to detect and return mimetype with stream file info (#552)

waveshell/pkg/packet/packet.go

@@ -485,6 +485,7 @@ type FileInfo struct {
 	ModTs    int64  `json:"modts"`
 	IsDir    bool   `json:"isdir,omitempty"`
 	Perm     int    `json:"perm"`
+	MimeType string `json:"mimetype,omitempty"`
 	NotFound bool   `json:"notfound,omitempty"` // when NotFound is set, Perm will be set to permission for directory
 }
 

waveshell/pkg/server/server.go

@@ -575,12 +575,14 @@ func (m *MServer) streamFile(pk *packet.StreamFilePacketType) {
 		m.Sender.SendPacket(resp)
 		return
 	}
+	mimeType := utilfn.DetectMimeType(pk.Path)
 	resp.Info = &packet.FileInfo{
-		Name:  pk.Path,
-		Size:  finfo.Size(),
-		ModTs: finfo.ModTime().UnixMilli(),
-		IsDir: finfo.IsDir(),
-		Perm:  int(finfo.Mode().Perm()),
+		Name:     pk.Path,
+		Size:     finfo.Size(),
+		ModTs:    finfo.ModTime().UnixMilli(),
+		IsDir:    finfo.IsDir(),
+		MimeType: mimeType,
+		Perm:     int(finfo.Mode().Perm()),
 	}
 	if pk.StatOnly {
 		resp.Done = true

waveshell/pkg/utilfn/utilfn.go

@@ -13,6 +13,8 @@ import (
 	"io"
 	"math"
 	mathrand "math/rand"
+	"net/http"
+	"os"
 	"regexp"
 	"sort"
 	"strings"
@@ -611,3 +613,25 @@ func CopyToChannel(outputCh chan<- []byte, reader io.Reader) error {
 		}
 	}
 }
+
+// on error just returns ""
+// does not return "application/octet-stream" as this is considered a detection failure
+func DetectMimeType(path string) string {
+	fd, err := os.Open(path)
+	if err != nil {
+		return ""
+	}
+	defer fd.Close()
+	buf := make([]byte, 512)
+	// ignore the error (EOF / UnexpectedEOF is fine, just process how much we got back)
+	n, _ := io.ReadAtLeast(fd, buf, 512)
+	if n == 0 {
+		return ""
+	}
+	buf = buf[:n]
+	rtn := http.DetectContentType(buf)
+	if rtn == "application/octet-stream" {
+		return ""
+	}
+	return rtn
+}

wavesrv/cmd/main-server.go

@@ -508,11 +508,8 @@ func HandleReadFile(w http.ResponseWriter, r *http.Request) {
 	qvals := r.URL.Query()
 	screenId := qvals.Get("screenid")
 	lineId := qvals.Get("lineid")
-	path := qvals.Get("path") // validate path?
-	contentType := qvals.Get("mimetype")
-	if contentType == "" {
-		contentType = "application/octet-stream"
-	}
+	path := qvals.Get("path")            // validate path?
+	contentType := qvals.Get("mimetype") // force a mimetype
 	if screenId == "" || lineId == "" {
 		w.WriteHeader(http.StatusInternalServerError)
 		w.Write([]byte("must specify sessionid, screenid, and lineid"))
@@ -533,7 +530,7 @@ func HandleReadFile(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(fmt.Sprintf(ErrorInvalidLineId, err)))
 		return
 	}
-	if !ContentTypeHeaderValidRe.MatchString(contentType) {
+	if contentType != "" && !ContentTypeHeaderValidRe.MatchString(contentType) {
 		w.WriteHeader(http.StatusInternalServerError)
 		w.Write([]byte("invalid mimetype specified"))
 		return
@@ -599,6 +596,12 @@ func HandleReadFile(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	infoJson, _ := json.Marshal(resp.Info)
+	if contentType == "" && resp.Info.MimeType != "" {
+		contentType = resp.Info.MimeType
+	}
+	if contentType == "" {
+		contentType = "application/octet-stream"
+	}
 	w.Header().Set("X-FileInfo", base64.StdEncoding.EncodeToString(infoJson))
 	w.Header().Set(ContentTypeHeaderKey, contentType)
 	w.WriteHeader(http.StatusOK)