Add support for direct downloads of server files

router/router.go

@@ -15,6 +15,7 @@ func Configure() *gin.Engine {
 
 	// These routes use signed URLs to validate access to the resource being requested.
 	router.GET("/download/backup", getDownloadBackup)
+	router.GET("/download/file", getDownloadFile)
 
 	// This route is special it sits above all of the other requests because we are
 	// using a JWT to authorize access to it, therefore it needs to be publicly

router/router_download.go

@@ -9,6 +9,7 @@ import (
 	"strconv"
 )
 
+// Handle a download request for a server backup.
 func getDownloadBackup(c *gin.Context) {
 	token := tokens.BackupPayload{}
 	if err := tokens.ParseToken([]byte(c.Query("token")), &token); err != nil {
@@ -43,3 +44,46 @@ func getDownloadBackup(c *gin.Context) {
 
 	bufio.NewReader(f).WriteTo(c.Writer)
 }
+
+// Handles downloading a specific file for a server.
+func getDownloadFile(c *gin.Context) {
+	token := tokens.FilePayload{}
+	if err := tokens.ParseToken([]byte(c.Query("token")), &token); err != nil {
+		TrackedError(err).AbortWithServerError(c)
+		return
+	}
+
+	s := GetServer(token.ServerUuid)
+	if s == nil || !token.IsUniqueRequest() {
+		c.AbortWithStatusJSON(http.StatusNotFound, gin.H{
+			"error": "The requested resource was not found on this server.",
+		})
+		return
+	}
+
+	p, _ := s.Filesystem.SafePath(token.FilePath)
+	st, err := os.Stat(p)
+	// If there is an error or we're somehow trying to download a directory, just
+	// respond with the appropriate error.
+	if err != nil {
+		TrackedServerError(err, s).AbortWithServerError(c)
+		return
+	} else if st.IsDir() {
+		c.AbortWithStatusJSON(http.StatusNotFound, gin.H{
+			"error": "The requested resource was not found on this server.",
+		})
+		return
+	}
+
+	f, err := os.Open(p)
+	if err != nil {
+		TrackedServerError(err, s).AbortWithServerError(c)
+		return
+	}
+
+	c.Header("Content-Length", strconv.Itoa(int(st.Size())))
+	c.Header("Content-Disposition", "attachment; filename="+st.Name())
+	c.Header("Content-Type", "application/octet-stream")
+
+	bufio.NewReader(f).WriteTo(c.Writer)
+}

router/tokens/file.go

@@ -0,0 +1,25 @@
+package tokens
+
+import (
+	"github.com/gbrlsnchs/jwt/v3"
+)
+
+type FilePayload struct {
+	jwt.Payload
+	FilePath   string `json:"file_path"`
+	ServerUuid string `json:"server_uuid"`
+	UniqueId   string `json:"unique_id"`
+}
+
+// Returns the JWT payload.
+func (p *FilePayload) GetPayload() *jwt.Payload {
+	return &p.Payload
+}
+
+// Determines if this JWT is valid for the given request cycle. If the
+// unique ID passed in the token has already been seen before this will
+// return false. This allows us to use this JWT as a one-time token that
+// validates all of the request.
+func (p *FilePayload) IsUniqueRequest() bool {
+	return getTokenStore().IsValidToken(p.UniqueId)
+}