122 lines
2.8 KiB
Go
122 lines
2.8 KiB
Go
// Package quotedprintable implements quoted-printable encoding as specified by
|
|
// RFC 2045.
|
|
package quotedprintable
|
|
|
|
import (
|
|
"bufio"
|
|
"bytes"
|
|
"fmt"
|
|
"io"
|
|
)
|
|
|
|
// Reader is a quoted-printable decoder.
|
|
type Reader struct {
|
|
br *bufio.Reader
|
|
rerr error // last read error
|
|
line []byte // to be consumed before more of br
|
|
}
|
|
|
|
// NewReader returns a quoted-printable reader, decoding from r.
|
|
func NewReader(r io.Reader) *Reader {
|
|
return &Reader{
|
|
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
|
|
// Accept badly encoded bytes.
|
|
case b >= 'a' && b <= 'f':
|
|
return b - 'a' + 10, nil
|
|
}
|
|
return 0, fmt.Errorf("quotedprintable: invalid hex byte 0x%02x", b)
|
|
}
|
|
|
|
func readHexByte(a, b byte) (byte, error) {
|
|
var hb, lb byte
|
|
var err error
|
|
if hb, err = fromHex(a); err != nil {
|
|
return 0, err
|
|
}
|
|
if lb, err = fromHex(b); 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("=")
|
|
)
|
|
|
|
// Read reads and decodes quoted-printable data from the underlying reader.
|
|
func (r *Reader) Read(p []byte) (n int, err error) {
|
|
// Deviations from RFC 2045:
|
|
// 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.
|
|
for len(p) > 0 {
|
|
if len(r.line) == 0 {
|
|
if r.rerr != nil {
|
|
return n, r.rerr
|
|
}
|
|
r.line, r.rerr = r.br.ReadSlice('\n')
|
|
|
|
// Does the line end in CRLF instead of just LF?
|
|
hasLF := bytes.HasSuffix(r.line, lf)
|
|
hasCR := bytes.HasSuffix(r.line, crlf)
|
|
wholeLine := r.line
|
|
r.line = bytes.TrimRightFunc(wholeLine, isQPDiscardWhitespace)
|
|
if bytes.HasSuffix(r.line, softSuffix) {
|
|
rightStripped := wholeLine[len(r.line):]
|
|
r.line = r.line[:len(r.line)-1]
|
|
if !bytes.HasPrefix(rightStripped, lf) && !bytes.HasPrefix(rightStripped, crlf) {
|
|
r.rerr = fmt.Errorf("quotedprintable: invalid bytes after =: %q", rightStripped)
|
|
}
|
|
} else if hasLF {
|
|
if hasCR {
|
|
r.line = append(r.line, '\r', '\n')
|
|
} else {
|
|
r.line = append(r.line, '\n')
|
|
}
|
|
}
|
|
continue
|
|
}
|
|
b := r.line[0]
|
|
|
|
switch {
|
|
case b == '=':
|
|
if len(r.line[1:]) < 2 {
|
|
return n, io.ErrUnexpectedEOF
|
|
}
|
|
b, err = readHexByte(r.line[1], r.line[2])
|
|
if err != nil {
|
|
return n, err
|
|
}
|
|
r.line = r.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("quotedprintable: invalid unescaped byte 0x%02x in body", b)
|
|
}
|
|
p[0] = b
|
|
p = p[1:]
|
|
r.line = r.line[1:]
|
|
n++
|
|
}
|
|
return n, nil
|
|
}
|