Imported Upstream version 1.1~hg20130304upstream/1.1_hg20130304

1 files changed, 28 insertions, 1 deletions

diff --git a/src/pkg/mime/multipart/writer.go b/src/pkg/mime/multipart/writer.go
index ec70be492..e13a956af 100644
--- a/src/pkg/mime/multipart/writer.go
+++ b/src/pkg/mime/multipart/writer.go
@@ -30,11 +30,38 @@ func NewWriter(w io.Writer) *Writer {
 	}
 }
 
-// Boundary returns the Writer's randomly selected boundary string.
+// Boundary returns the Writer's boundary.
 func (w *Writer) Boundary() string {
 	return w.boundary
 }
 
+// SetBoundary overrides the Writer's default randomly-generated
+// boundary separator with an explicit value.
+//
+// SetBoundary must be called before any parts are created, may only
+// contain certain ASCII characters, and must be 1-69 bytes long.
+func (w *Writer) SetBoundary(boundary string) error {
+	if w.lastpart != nil {
+		return errors.New("mime: SetBoundary called after write")
+	}
+	// rfc2046#section-5.1.1
+	if len(boundary) < 1 || len(boundary) > 69 {
+		return errors.New("mime: invalid boundary length")
+	}
+	for _, b := range boundary {
+		if 'A' <= b && b <= 'Z' || 'a' <= b && b <= 'z' || '0' <= b && b <= '9' {
+			continue
+		}
+		switch b {
+		case '\'', '(', ')', '+', '_', ',', '-', '.', '/', ':', '=', '?':
+			continue
+		}
+		return errors.New("mime: invalid boundary character")
+	}
+	w.boundary = boundary
+	return nil
+}
+
 // FormDataContentType returns the Content-Type for an HTTP
 // multipart/form-data with this Writer's Boundary.
 func (w *Writer) FormDataContentType() string {