Add missing files, update style

internal/web/upload.go

@@ -0,0 +1,42 @@
+package web
+
+import (
+	"errors"
+	"fmt"
+	"mime/multipart"
+	"net/http"
+	"path"
+	"strings"
+)
+
+// parseUpload parses a multipart form with a file in the "file" field. On
+// failure it returns an HTTP status and a message for the page.
+//
+// Files bigger than 1 MB are spooled to temporary files rather than kept in
+// memory; net/http removes them when the handler returns.
+func (s *Server) parseUpload(w http.ResponseWriter, r *http.Request) (multipart.File, *multipart.FileHeader, int, string) {
+	// Allow some slack over the file size limit for the multipart framing and form fields.
+	r.Body = http.MaxBytesReader(w, r.Body, s.cfg.MaxUploadBytes+64<<10)
+	if err := r.ParseMultipartForm(1 << 20); err != nil {
+		var tooBig *http.MaxBytesError
+		if errors.As(err, &tooBig) {
+			return nil, nil, http.StatusRequestEntityTooLarge, "file too large; the maximum upload is " + s.maxUpload()
+		}
+		return nil, nil, http.StatusBadRequest, "bad upload: " + err.Error()
+	}
+	file, hdr, err := r.FormFile("file")
+	if err != nil {
+		return nil, nil, http.StatusBadRequest, "choose a pcap file"
+	}
+	return file, hdr, 0, ""
+}
+
+func (s *Server) maxUpload() string {
+	return fmt.Sprintf("%d MB", s.cfg.MaxUploadBytes/1e6)
+}
+
+// uploadStem returns the sanitized name of an uploaded file without its extension.
+func uploadStem(hdr *multipart.FileHeader) string {
+	name := safeName(hdr.Filename, "capture.pcap")
+	return strings.TrimSuffix(name, path.Ext(name))
+}