1 files changed, 268 insertions, 0 deletions
diff --git a/src/pkg/mime/multipart/multipart.go b/src/pkg/mime/multipart/multipart.go
new file mode 100644
index 000000000..2533bd337
--- /dev/null
+++ b/src/pkg/mime/multipart/multipart.go
@@ -0,0 +1,268 @@
+// Copyright 2010 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 implements MIME multipart parsing, as defined in RFC
+2046.
+
+The implementation is sufficient for HTTP (RFC 2388) and the multipart
+bodies generated by popular browsers.
+*/
+package multipart
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"mime"
+	"net/textproto"
+	"os"
+)
+
+// TODO(bradfitz): inline these once the compiler can inline them in
+// read-only situation (such as bytes.HasSuffix)
+var lf = []byte("\n")
+var crlf = []byte("\r\n")
+
+var emptyParams = make(map[string]string)
+
+// A Part represents a single part in a multipart body.
+type Part struct {
+	// The headers of the body, if any, with the keys canonicalized
+	// in the same fashion that the Go http.Request headers are.
+	// i.e. "foo-bar" changes case to "Foo-Bar"
+	Header textproto.MIMEHeader
+
+	buffer *bytes.Buffer
+	mr     *Reader
+
+	disposition       string
+	dispositionParams map[string]string
+}
+
+// FormName returns the name parameter if p has a Content-Disposition
+// of type "form-data".  Otherwise it returns the empty string.
+func (p *Part) FormName() string {
+	// See http://tools.ietf.org/html/rfc2183 section 2 for EBNF
+	// of Content-Disposition value format.
+	if p.dispositionParams == nil {
+		p.parseContentDisposition()
+	}
+	if p.disposition != "form-data" {
+		return ""
+	}
+	return p.dispositionParams["name"]
+}
+
+// FileName returns the filename parameter of the Part's
+// Content-Disposition header.
+func (p *Part) FileName() string {
+	if p.dispositionParams == nil {
+		p.parseContentDisposition()
+	}
+	return p.dispositionParams["filename"]
+}
+
+func (p *Part) parseContentDisposition() {
+	v := p.Header.Get("Content-Disposition")
+	p.disposition, p.dispositionParams = mime.ParseMediaType(v)
+	if p.dispositionParams == nil {
+		p.dispositionParams = emptyParams
+	}
+}
+
+// NewReader creates a new multipart Reader reading from r using the
+// given MIME boundary.
+func NewReader(reader io.Reader, boundary string) *Reader {
+	b := []byte("\r\n--" + boundary + "--")
+	return &Reader{
+		bufReader: bufio.NewReader(reader),
+
+		nl:               b[:2],
+		nlDashBoundary:   b[:len(b)-2],
+		dashBoundaryDash: b[2:],
+		dashBoundary:     b[2 : len(b)-2],
+	}
+}
+
+func newPart(mr *Reader) (*Part, os.Error) {
+	bp := &Part{
+		Header: make(map[string][]string),
+		mr:     mr,
+		buffer: new(bytes.Buffer),
+	}
+	if err := bp.populateHeaders(); err != nil {
+		return nil, err
+	}
+	return bp, nil
+}
+
+func (bp *Part) populateHeaders() os.Error {
+	r := textproto.NewReader(bp.mr.bufReader)
+	header, err := r.ReadMIMEHeader()
+	if err == nil {
+		bp.Header = header
+	}
+	return err
+}
+
+// Read reads the body of a part, after its headers and before the
+// next part (if any) begins.
+func (bp *Part) Read(p []byte) (n int, err os.Error) {
+	if bp.buffer.Len() >= len(p) {
+		// Internal buffer of unconsumed data is large enough for
+		// the read request.  No need to parse more at the moment.
+		return bp.buffer.Read(p)
+	}
+	peek, err := bp.mr.bufReader.Peek(4096) // TODO(bradfitz): add buffer size accessor
+	unexpectedEof := err == os.EOF
+	if err != nil && !unexpectedEof {
+		return 0, fmt.Errorf("multipart: Part Read: %v", err)
+	}
+	if peek == nil {
+		panic("nil peek buf")
+	}
+
+	// Search the peek buffer for "\r\n--boundary". If found,
+	// consume everything up to the boundary. If not, consume only
+	// as much of the peek buffer as cannot hold the boundary
+	// string.
+	nCopy := 0
+	foundBoundary := false
+	if idx := bytes.Index(peek, bp.mr.nlDashBoundary); idx != -1 {
+		nCopy = idx
+		foundBoundary = true
+	} else if safeCount := len(peek) - len(bp.mr.nlDashBoundary); safeCount > 0 {
+		nCopy = safeCount
+	} else if unexpectedEof {
+		// If we've run out of peek buffer and the boundary
+		// wasn't found (and can't possibly fit), we must have
+		// hit the end of the file unexpectedly.
+		return 0, io.ErrUnexpectedEOF
+	}
+	if nCopy > 0 {
+		if _, err := io.Copyn(bp.buffer, bp.mr.bufReader, int64(nCopy)); err != nil {
+			return 0, err
+		}
+	}
+	n, err = bp.buffer.Read(p)
+	if err == os.EOF && !foundBoundary {
+		// If the boundary hasn't been reached there's more to
+		// read, so don't pass through an EOF from the buffer
+		err = nil
+	}
+	return
+}
+
+func (bp *Part) Close() os.Error {
+	io.Copy(ioutil.Discard, bp)
+	return nil
+}
+
+// Reader is an iterator over parts in a MIME multipart body.
+// Reader's underlying parser consumes its input as needed.  Seeking
+// isn't supported.
+type Reader struct {
+	bufReader *bufio.Reader
+
+	currentPart *Part
+	partsRead   int
+
+	nl, nlDashBoundary, dashBoundaryDash, dashBoundary []byte
+}
+
+// NextPart returns the next part in the multipart or an error.
+// When there are no more parts, the error os.EOF is returned.
+func (mr *Reader) NextPart() (*Part, os.Error) {
+	if mr.currentPart != nil {
+		mr.currentPart.Close()
+	}
+
+	expectNewPart := false
+	for {
+		line, err := mr.bufReader.ReadSlice('\n')
+		if err != nil {
+			return nil, fmt.Errorf("multipart: NextPart: %v", err)
+		}
+
+		if mr.isBoundaryDelimiterLine(line) {
+			mr.partsRead++
+			bp, err := newPart(mr)
+			if err != nil {
+				return nil, err
+			}
+			mr.currentPart = bp
+			return bp, nil
+		}
+
+		if hasPrefixThenNewline(line, mr.dashBoundaryDash) {
+			// Expected EOF
+			return nil, os.EOF
+		}
+
+		if expectNewPart {
+			return nil, fmt.Errorf("multipart: expecting a new Part; got line %q", string(line))
+		}
+
+		if mr.partsRead == 0 {
+			// skip line
+			continue
+		}
+
+		// Consume the "\n" or "\r\n" separator between the
+		// body of the previous part and the boundary line we
+		// now expect will follow. (either a new part or the
+		// end boundary)
+		if bytes.Equal(line, mr.nl) {
+			expectNewPart = true
+			continue
+		}
+
+		return nil, fmt.Errorf("multipart: unexpected line in Next(): %q", line)
+	}
+	panic("unreachable")
+}
+
+func (mr *Reader) isBoundaryDelimiterLine(line []byte) bool {
+	// http://tools.ietf.org/html/rfc2046#section-5.1
+	//   The boundary delimiter line is then defined as a line
+	//   consisting entirely of two hyphen characters ("-",
+	//   decimal value 45) followed by the boundary parameter
+	//   value from the Content-Type header field, optional linear
+	//   whitespace, and a terminating CRLF.
+	if !bytes.HasPrefix(line, mr.dashBoundary) {
+		return false
+	}
+	if bytes.HasSuffix(line, mr.nl) {
+		return onlyHorizontalWhitespace(line[len(mr.dashBoundary) : len(line)-len(mr.nl)])
+	}
+	// Violate the spec and also support newlines without the
+	// carriage return...
+	if mr.partsRead == 0 && bytes.HasSuffix(line, lf) {
+		if onlyHorizontalWhitespace(line[len(mr.dashBoundary) : len(line)-1]) {
+			mr.nl = mr.nl[1:]
+			mr.nlDashBoundary = mr.nlDashBoundary[1:]
+			return true
+		}
+	}
+	return false
+}
+
+func onlyHorizontalWhitespace(s []byte) bool {
+	for _, b := range s {
+		if b != ' ' && b != '\t' {
+			return false
+		}
+	}
+	return true
+}
+
+func hasPrefixThenNewline(s, prefix []byte) bool {
+	return bytes.HasPrefix(s, prefix) &&
+		(len(s) == len(prefix)+1 && s[len(s)-1] == '\n' ||
+			len(s) == len(prefix)+2 && bytes.HasSuffix(s, crlf))
+}