| // Copyright 2012 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. |
| |
| // The file define a quoted-printable decoder, as specified in RFC 2045. |
| // Deviations: |
| // 1. in addition to "=\r\n", "=\n" is also treated as soft line break. |
| // 2. it will pass through a '\r' or '\n' not preceded by '=', consistent |
| // with other broken QP encoders & decoders. |
| |
| package multipart |
| |
| import ( |
| "bufio" |
| "bytes" |
| "fmt" |
| "io" |
| ) |
| |
| type qpReader struct { |
| br *bufio.Reader |
| rerr error // last read error |
| line []byte // to be consumed before more of br |
| } |
| |
| func newQuotedPrintableReader(r io.Reader) io.Reader { |
| return &qpReader{ |
| br: bufio.NewReader(r), |
| } |
| } |
| |
| func fromHex(b byte) (byte, error) { |
| switch { |
| case b >= '0' && b <= '9': |
| return b - '0', nil |
| case b >= 'A' && b <= 'F': |
| return b - 'A' + 10, nil |
| } |
| return 0, fmt.Errorf("multipart: invalid quoted-printable hex byte 0x%02x", b) |
| } |
| |
| func (q *qpReader) readHexByte(v []byte) (b byte, err error) { |
| if len(v) < 2 { |
| return 0, io.ErrUnexpectedEOF |
| } |
| var hb, lb byte |
| if hb, err = fromHex(v[0]); err != nil { |
| return 0, err |
| } |
| if lb, err = fromHex(v[1]); err != nil { |
| return 0, err |
| } |
| return hb<<4 | lb, nil |
| } |
| |
| func isQPDiscardWhitespace(r rune) bool { |
| switch r { |
| case '\n', '\r', ' ', '\t': |
| return true |
| } |
| return false |
| } |
| |
| var ( |
| crlf = []byte("\r\n") |
| lf = []byte("\n") |
| softSuffix = []byte("=") |
| ) |
| |
| func (q *qpReader) Read(p []byte) (n int, err error) { |
| for len(p) > 0 { |
| if len(q.line) == 0 { |
| if q.rerr != nil { |
| return n, q.rerr |
| } |
| q.line, q.rerr = q.br.ReadSlice('\n') |
| |
| // Does the line end in CRLF instead of just LF? |
| hasLF := bytes.HasSuffix(q.line, lf) |
| hasCR := bytes.HasSuffix(q.line, crlf) |
| wholeLine := q.line |
| q.line = bytes.TrimRightFunc(wholeLine, isQPDiscardWhitespace) |
| if bytes.HasSuffix(q.line, softSuffix) { |
| rightStripped := wholeLine[len(q.line):] |
| q.line = q.line[:len(q.line)-1] |
| if !bytes.HasPrefix(rightStripped, lf) && !bytes.HasPrefix(rightStripped, crlf) { |
| q.rerr = fmt.Errorf("multipart: invalid bytes after =: %q", rightStripped) |
| } |
| } else if hasLF { |
| if hasCR { |
| q.line = append(q.line, '\r', '\n') |
| } else { |
| q.line = append(q.line, '\n') |
| } |
| } |
| continue |
| } |
| b := q.line[0] |
| |
| switch { |
| case b == '=': |
| b, err = q.readHexByte(q.line[1:]) |
| if err != nil { |
| return n, err |
| } |
| q.line = q.line[2:] // 2 of the 3; other 1 is done below |
| case b == '\t' || b == '\r' || b == '\n': |
| break |
| case b < ' ' || b > '~': |
| return n, fmt.Errorf("multipart: invalid unescaped byte 0x%02x in quoted-printable body", b) |
| } |
| p[0] = b |
| p = p[1:] |
| q.line = q.line[1:] |
| n++ |
| } |
| return n, nil |
| } |