--- /dev/null
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package multipart
+
+import (
+ "bytes"
+ "fmt"
+ "io"
+ "net/textproto"
+ "os"
+ "rand"
+ "strings"
+)
+
+// Writer is used to generate multipart messages.
+type Writer struct {
+ // Boundary is the random boundary string between
+ // parts. NewWriter will generate this but it must
+ // not be changed after a part has been created.
+ // Setting this to an invalid value will generate
+ // malformed messages.
+ Boundary string
+
+ w io.Writer
+ lastpart *part
+}
+
+// NewWriter returns a new multipart Writer with a random boundary,
+// writing to w.
+func NewWriter(w io.Writer) *Writer {
+ return &Writer{
+ w: w,
+ Boundary: randomBoundary(),
+ }
+}
+
+// FormDataContentType returns the Content-Type for an HTTP
+// multipart/form-data with this Writer's Boundary.
+func (w *Writer) FormDataContentType() string {
+ return "multipart/form-data; boundary=" + w.Boundary
+}
+
+const randChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+func randomBoundary() string {
+ var buf [60]byte
+ for i := range buf {
+ buf[i] = randChars[rand.Intn(len(randChars))]
+ }
+ return string(buf[:])
+}
+
+// CreatePart creates a new multipart section with the provided
+// header. The previous part, if still open, is closed. The body of
+// the part should be written to the returned WriteCloser. Closing the
+// returned WriteCloser after writing is optional.
+func (w *Writer) CreatePart(header textproto.MIMEHeader) (io.WriteCloser, os.Error) {
+ if w.lastpart != nil {
+ if err := w.lastpart.Close(); err != nil {
+ return nil, err
+ }
+ }
+ var b bytes.Buffer
+ fmt.Fprintf(&b, "\r\n--%s\r\n", w.Boundary)
+ // TODO(bradfitz): move this to textproto.MimeHeader.Write(w), have it sort
+ // and clean, like http.Header.Write(w) does.
+ for k, vv := range header {
+ for _, v := range vv {
+ fmt.Fprintf(&b, "%s: %s\r\n", k, v)
+ }
+ }
+ fmt.Fprintf(&b, "\r\n")
+ _, err := io.Copy(w.w, &b)
+ if err != nil {
+ return nil, err
+ }
+ p := &part{
+ mw: w,
+ }
+ w.lastpart = p
+ return p, nil
+}
+
+func escapeQuotes(s string) string {
+ s = strings.Replace(s, "\\", "\\\\", -1)
+ s = strings.Replace(s, "\"", "\\\"", -1)
+ return s
+}
+
+// CreateFormFile is a convenience wrapper around CreatePart. It creates
+// a new form-data header with the provided field name and file name.
+func (w *Writer) CreateFormFile(fieldname, filename string) (io.WriteCloser, os.Error) {
+ h := make(textproto.MIMEHeader)
+ h.Set("Content-Disposition",
+ fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
+ escapeQuotes(fieldname), escapeQuotes(filename)))
+ h.Set("Content-Type", "application/octet-stream")
+ return w.CreatePart(h)
+}
+
+// CreateFormField is a convenience wrapper around CreatePart. It creates
+// a new form-data header with the provided field name.
+func (w *Writer) CreateFormField(fieldname string) (io.WriteCloser, os.Error) {
+ h := make(textproto.MIMEHeader)
+ h.Set("Content-Disposition",
+ fmt.Sprintf(`form-data; name="%s"`, escapeQuotes(fieldname)))
+ return w.CreatePart(h)
+}
+
+// WriteField is a convenience wrapper around CreateFormField. It creates and
+// writes a part with the provided name and value.
+func (w *Writer) WriteField(fieldname, value string) os.Error {
+ p, err := w.CreateFormField(fieldname)
+ if err != nil {
+ return err
+ }
+ _, err = p.Write([]byte(value))
+ if err != nil {
+ return err
+ }
+ return p.Close()
+}
+
+// Close finishes the multipart message. It closes the previous part,
+// if still open, and writes the trailing boundary end line to the
+// output.
+func (w *Writer) Close() os.Error {
+ if w.lastpart != nil {
+ if err := w.lastpart.Close(); err != nil {
+ return err
+ }
+ w.lastpart = nil
+ }
+ _, err := fmt.Fprintf(w.w, "\r\n--%s--\r\n", w.Boundary)
+ return err
+}
+
+type part struct {
+ mw *Writer
+ closed bool
+ we os.Error // last error that occurred writing
+}
+
+func (p *part) Close() os.Error {
+ p.closed = true
+ return p.we
+}
+
+func (p *part) Write(d []byte) (n int, err os.Error) {
+ if p.closed {
+ return 0, os.NewError("multipart: Write after Close")
+ }
+ n, err = p.mw.w.Write(d)
+ if err != nil {
+ p.we = err
+ }
+ return
+}
--- /dev/null
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package multipart
+
+import (
+ "bytes"
+ "io/ioutil"
+ "testing"
+)
+
+func TestWriter(t *testing.T) {
+ fileContents := []byte("my file contents")
+
+ var b bytes.Buffer
+ w := NewWriter(&b)
+ {
+ part, err := w.CreateFormFile("myfile", "my-file.txt")
+ if err != nil {
+ t.Fatalf("CreateFormFile: %v", err)
+ }
+ part.Write(fileContents)
+ err = w.WriteField("key", "val")
+ if err != nil {
+ t.Fatalf("CreateFormFieldValue: %v", err)
+ }
+ part.Write([]byte("val"))
+ err = w.Close()
+ if err != nil {
+ t.Fatalf("Close: %v", err)
+ }
+ }
+
+ r := NewReader(&b, w.Boundary)
+
+ part, err := r.NextPart()
+ if err != nil {
+ t.Fatalf("part 1: %v", err)
+ }
+ if g, e := part.FormName(), "myfile"; g != e {
+ t.Errorf("part 1: want form name %q, got %q", e, g)
+ }
+ slurp, err := ioutil.ReadAll(part)
+ if err != nil {
+ t.Fatalf("part 1: ReadAll: %v", err)
+ }
+ if e, g := string(fileContents), string(slurp); e != g {
+ t.Errorf("part 1: want contents %q, got %q", e, g)
+ }
+
+ part, err = r.NextPart()
+ if err != nil {
+ t.Fatalf("part 2: %v", err)
+ }
+ if g, e := part.FormName(), "key"; g != e {
+ t.Errorf("part 2: want form name %q, got %q", e, g)
+ }
+ slurp, err = ioutil.ReadAll(part)
+ if err != nil {
+ t.Fatalf("part 2: ReadAll: %v", err)
+ }
+ if e, g := "val", string(slurp); e != g {
+ t.Errorf("part 2: want contents %q, got %q", e, g)
+ }
+
+ part, err = r.NextPart()
+ if part != nil || err == nil {
+ t.Fatalf("expected end of parts; got %v, %v", part, err)
+ }
+}