added vendor

2026-01-22 17:31:03 +01:00 · 2020-01-13 19:56:34 +08:00
parent c67c1be52a
commit b2f3578aea
20 changed files with 1760 additions and 0 deletions
--- a/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/LICENSE
+++ b/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/LICENSE
@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) 2014 Alexandre Cesaro
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--- a/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/README.md
+++ b/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/README.md
@@ -0,0 +1,16 @@
+# quotedprintable
+
+## Introduction
+
+Package quotedprintable implements quoted-printable and message header encoding
+as specified by RFC 2045 and RFC 2047.
+
+It is a copy of the Go 1.5 package `mime/quotedprintable`. It also includes
+the new functions of package `mime` concerning RFC 2047.
+
+This code has minor changes with the standard library code in order to work
+with Go 1.0 and newer. 
+
+## Documentation
+
+https://godoc.org/gopkg.in/alexcesaro/quotedprintable.v3
--- a/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/encodedword.go
+++ b/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/encodedword.go
@@ -0,0 +1,279 @@
+package quotedprintable
+
+import (
+	"bytes"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+// A WordEncoder is a RFC 2047 encoded-word encoder.
+type WordEncoder byte
+
+const (
+	// BEncoding represents Base64 encoding scheme as defined by RFC 2045.
+	BEncoding = WordEncoder('b')
+	// QEncoding represents the Q-encoding scheme as defined by RFC 2047.
+	QEncoding = WordEncoder('q')
+)
+
+var (
+	errInvalidWord = errors.New("mime: invalid RFC 2047 encoded-word")
+)
+
+// Encode returns the encoded-word form of s. If s is ASCII without special
+// characters, it is returned unchanged. The provided charset is the IANA
+// charset name of s. It is case insensitive.
+func (e WordEncoder) Encode(charset, s string) string {
+	if !needsEncoding(s) {
+		return s
+	}
+	return e.encodeWord(charset, s)
+}
+
+func needsEncoding(s string) bool {
+	for _, b := range s {
+		if (b < ' ' || b > '~') && b != '\t' {
+			return true
+		}
+	}
+	return false
+}
+
+// encodeWord encodes a string into an encoded-word.
+func (e WordEncoder) encodeWord(charset, s string) string {
+	buf := getBuffer()
+	defer putBuffer(buf)
+
+	buf.WriteString("=?")
+	buf.WriteString(charset)
+	buf.WriteByte('?')
+	buf.WriteByte(byte(e))
+	buf.WriteByte('?')
+
+	if e == BEncoding {
+		w := base64.NewEncoder(base64.StdEncoding, buf)
+		io.WriteString(w, s)
+		w.Close()
+	} else {
+		enc := make([]byte, 3)
+		for i := 0; i < len(s); i++ {
+			b := s[i]
+			switch {
+			case b == ' ':
+				buf.WriteByte('_')
+			case b <= '~' && b >= '!' && b != '=' && b != '?' && b != '_':
+				buf.WriteByte(b)
+			default:
+				enc[0] = '='
+				enc[1] = upperhex[b>>4]
+				enc[2] = upperhex[b&0x0f]
+				buf.Write(enc)
+			}
+		}
+	}
+	buf.WriteString("?=")
+	return buf.String()
+}
+
+const upperhex = "0123456789ABCDEF"
+
+// A WordDecoder decodes MIME headers containing RFC 2047 encoded-words.
+type WordDecoder struct {
+	// CharsetReader, if non-nil, defines a function to generate
+	// charset-conversion readers, converting from the provided
+	// charset into UTF-8.
+	// Charsets are always lower-case. utf-8, iso-8859-1 and us-ascii charsets
+	// are handled by default.
+	// One of the the CharsetReader's result values must be non-nil.
+	CharsetReader func(charset string, input io.Reader) (io.Reader, error)
+}
+
+// Decode decodes an encoded-word. If word is not a valid RFC 2047 encoded-word,
+// word is returned unchanged.
+func (d *WordDecoder) Decode(word string) (string, error) {
+	fields := strings.Split(word, "?") // TODO: remove allocation?
+	if len(fields) != 5 || fields[0] != "=" || fields[4] != "=" || len(fields[2]) != 1 {
+		return "", errInvalidWord
+	}
+
+	content, err := decode(fields[2][0], fields[3])
+	if err != nil {
+		return "", err
+	}
+
+	buf := getBuffer()
+	defer putBuffer(buf)
+
+	if err := d.convert(buf, fields[1], content); err != nil {
+		return "", err
+	}
+
+	return buf.String(), nil
+}
+
+// DecodeHeader decodes all encoded-words of the given string. It returns an
+// error if and only if CharsetReader of d returns an error.
+func (d *WordDecoder) DecodeHeader(header string) (string, error) {
+	// If there is no encoded-word, returns before creating a buffer.
+	i := strings.Index(header, "=?")
+	if i == -1 {
+		return header, nil
+	}
+
+	buf := getBuffer()
+	defer putBuffer(buf)
+
+	buf.WriteString(header[:i])
+	header = header[i:]
+
+	betweenWords := false
+	for {
+		start := strings.Index(header, "=?")
+		if start == -1 {
+			break
+		}
+		cur := start + len("=?")
+
+		i := strings.Index(header[cur:], "?")
+		if i == -1 {
+			break
+		}
+		charset := header[cur : cur+i]
+		cur += i + len("?")
+
+		if len(header) < cur+len("Q??=") {
+			break
+		}
+		encoding := header[cur]
+		cur++
+
+		if header[cur] != '?' {
+			break
+		}
+		cur++
+
+		j := strings.Index(header[cur:], "?=")
+		if j == -1 {
+			break
+		}
+		text := header[cur : cur+j]
+		end := cur + j + len("?=")
+
+		content, err := decode(encoding, text)
+		if err != nil {
+			betweenWords = false
+			buf.WriteString(header[:start+2])
+			header = header[start+2:]
+			continue
+		}
+
+		// Write characters before the encoded-word. White-space and newline
+		// characters separating two encoded-words must be deleted.
+		if start > 0 && (!betweenWords || hasNonWhitespace(header[:start])) {
+			buf.WriteString(header[:start])
+		}
+
+		if err := d.convert(buf, charset, content); err != nil {
+			return "", err
+		}
+
+		header = header[end:]
+		betweenWords = true
+	}
+
+	if len(header) > 0 {
+		buf.WriteString(header)
+	}
+
+	return buf.String(), nil
+}
+
+func decode(encoding byte, text string) ([]byte, error) {
+	switch encoding {
+	case 'B', 'b':
+		return base64.StdEncoding.DecodeString(text)
+	case 'Q', 'q':
+		return qDecode(text)
+	}
+	return nil, errInvalidWord
+}
+
+func (d *WordDecoder) convert(buf *bytes.Buffer, charset string, content []byte) error {
+	switch {
+	case strings.EqualFold("utf-8", charset):
+		buf.Write(content)
+	case strings.EqualFold("iso-8859-1", charset):
+		for _, c := range content {
+			buf.WriteRune(rune(c))
+		}
+	case strings.EqualFold("us-ascii", charset):
+		for _, c := range content {
+			if c >= utf8.RuneSelf {
+				buf.WriteRune(unicode.ReplacementChar)
+			} else {
+				buf.WriteByte(c)
+			}
+		}
+	default:
+		if d.CharsetReader == nil {
+			return fmt.Errorf("mime: unhandled charset %q", charset)
+		}
+		r, err := d.CharsetReader(strings.ToLower(charset), bytes.NewReader(content))
+		if err != nil {
+			return err
+		}
+		if _, err = buf.ReadFrom(r); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// hasNonWhitespace reports whether s (assumed to be ASCII) contains at least
+// one byte of non-whitespace.
+func hasNonWhitespace(s string) bool {
+	for _, b := range s {
+		switch b {
+		// Encoded-words can only be separated by linear white spaces which does
+		// not include vertical tabs (\v).
+		case ' ', '\t', '\n', '\r':
+		default:
+			return true
+		}
+	}
+	return false
+}
+
+// qDecode decodes a Q encoded string.
+func qDecode(s string) ([]byte, error) {
+	dec := make([]byte, len(s))
+	n := 0
+	for i := 0; i < len(s); i++ {
+		switch c := s[i]; {
+		case c == '_':
+			dec[n] = ' '
+		case c == '=':
+			if i+2 >= len(s) {
+				return nil, errInvalidWord
+			}
+			b, err := readHexByte(s[i+1], s[i+2])
+			if err != nil {
+				return nil, err
+			}
+			dec[n] = b
+			i += 2
+		case (c <= '~' && c >= ' ') || c == '\n' || c == '\r' || c == '\t':
+			dec[n] = c
+		default:
+			return nil, errInvalidWord
+		}
+		n++
+	}
+
+	return dec[:n], nil
+}
--- a/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/pool.go
+++ b/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/pool.go
@@ -0,0 +1,26 @@
+// +build go1.3
+
+package quotedprintable
+
+import (
+	"bytes"
+	"sync"
+)
+
+var bufPool = sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
+func getBuffer() *bytes.Buffer {
+	return bufPool.Get().(*bytes.Buffer)
+}
+
+func putBuffer(buf *bytes.Buffer) {
+	if buf.Len() > 1024 {
+		return
+	}
+	buf.Reset()
+	bufPool.Put(buf)
+}
--- a/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/pool_go12.go
+++ b/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/pool_go12.go
@@ -0,0 +1,24 @@
+// +build !go1.3
+
+package quotedprintable
+
+import "bytes"
+
+var ch = make(chan *bytes.Buffer, 32)
+
+func getBuffer() *bytes.Buffer {
+	select {
+	case buf := <-ch:
+		return buf
+	default:
+	}
+	return new(bytes.Buffer)
+}
+
+func putBuffer(buf *bytes.Buffer) {
+	buf.Reset()
+	select {
+	case ch <- buf:
+	default:
+	}
+}
--- a/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/reader.go
+++ b/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/reader.go
@@ -0,0 +1,121 @@
+// 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
+}
--- a/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/writer.go
+++ b/backend/vendor/gopkg.in/alexcesaro/quotedprintable.v3/writer.go
@@ -0,0 +1,166 @@
+package quotedprintable
+
+import "io"
+
+const lineMaxLen = 76
+
+// A Writer is a quoted-printable writer that implements io.WriteCloser.
+type Writer struct {
+	// Binary mode treats the writer's input as pure binary and processes end of
+	// line bytes as binary data.
+	Binary bool
+
+	w    io.Writer
+	i    int
+	line [78]byte
+	cr   bool
+}
+
+// NewWriter returns a new Writer that writes to w.
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{w: w}
+}
+
+// Write encodes p using quoted-printable encoding and writes it to the
+// underlying io.Writer. It limits line length to 76 characters. The encoded
+// bytes are not necessarily flushed until the Writer is closed.
+func (w *Writer) Write(p []byte) (n int, err error) {
+	for i, b := range p {
+		switch {
+		// Simple writes are done in batch.
+		case b >= '!' && b <= '~' && b != '=':
+			continue
+		case isWhitespace(b) || !w.Binary && (b == '\n' || b == '\r'):
+			continue
+		}
+
+		if i > n {
+			if err := w.write(p[n:i]); err != nil {
+				return n, err
+			}
+			n = i
+		}
+
+		if err := w.encode(b); err != nil {
+			return n, err
+		}
+		n++
+	}
+
+	if n == len(p) {
+		return n, nil
+	}
+
+	if err := w.write(p[n:]); err != nil {
+		return n, err
+	}
+
+	return len(p), nil
+}
+
+// Close closes the Writer, flushing any unwritten data to the underlying
+// io.Writer, but does not close the underlying io.Writer.
+func (w *Writer) Close() error {
+	if err := w.checkLastByte(); err != nil {
+		return err
+	}
+
+	return w.flush()
+}
+
+// write limits text encoded in quoted-printable to 76 characters per line.
+func (w *Writer) write(p []byte) error {
+	for _, b := range p {
+		if b == '\n' || b == '\r' {
+			// If the previous byte was \r, the CRLF has already been inserted.
+			if w.cr && b == '\n' {
+				w.cr = false
+				continue
+			}
+
+			if b == '\r' {
+				w.cr = true
+			}
+
+			if err := w.checkLastByte(); err != nil {
+				return err
+			}
+			if err := w.insertCRLF(); err != nil {
+				return err
+			}
+			continue
+		}
+
+		if w.i == lineMaxLen-1 {
+			if err := w.insertSoftLineBreak(); err != nil {
+				return err
+			}
+		}
+
+		w.line[w.i] = b
+		w.i++
+		w.cr = false
+	}
+
+	return nil
+}
+
+func (w *Writer) encode(b byte) error {
+	if lineMaxLen-1-w.i < 3 {
+		if err := w.insertSoftLineBreak(); err != nil {
+			return err
+		}
+	}
+
+	w.line[w.i] = '='
+	w.line[w.i+1] = upperhex[b>>4]
+	w.line[w.i+2] = upperhex[b&0x0f]
+	w.i += 3
+
+	return nil
+}
+
+// checkLastByte encodes the last buffered byte if it is a space or a tab.
+func (w *Writer) checkLastByte() error {
+	if w.i == 0 {
+		return nil
+	}
+
+	b := w.line[w.i-1]
+	if isWhitespace(b) {
+		w.i--
+		if err := w.encode(b); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (w *Writer) insertSoftLineBreak() error {
+	w.line[w.i] = '='
+	w.i++
+
+	return w.insertCRLF()
+}
+
+func (w *Writer) insertCRLF() error {
+	w.line[w.i] = '\r'
+	w.line[w.i+1] = '\n'
+	w.i += 2
+
+	return w.flush()
+}
+
+func (w *Writer) flush() error {
+	if _, err := w.w.Write(w.line[:w.i]); err != nil {
+		return err
+	}
+
+	w.i = 0
+	return nil
+}
+
+func isWhitespace(b byte) bool {
+	return b == ' ' || b == '\t'
+}
--- a/backend/vendor/gopkg.in/gomail.v2/.travis.yml
+++ b/backend/vendor/gopkg.in/gomail.v2/.travis.yml
@@ -0,0 +1,8 @@
+language: go
+
+go:
+  - 1.2
+  - 1.3
+  - 1.4
+  - 1.5
+  - tip
--- a/backend/vendor/gopkg.in/gomail.v2/CHANGELOG.md
+++ b/backend/vendor/gopkg.in/gomail.v2/CHANGELOG.md
@@ -0,0 +1,20 @@
+# Change Log
+All notable changes to this project will be documented in this file.
+This project adheres to [Semantic Versioning](http://semver.org/).
+
+## [2.0.0] - 2015-09-02
+
+- Mailer has been removed. It has been replaced by Dialer and Sender.
+- `File` type and the `CreateFile` and `OpenFile` functions have been removed.
+- `Message.Attach` and `Message.Embed` have a new signature.
+- `Message.GetBodyWriter` has been removed. Use `Message.AddAlternativeWriter`
+instead.
+- `Message.Export` has been removed. `Message.WriteTo` can be used instead.
+- `Message.DelHeader` has been removed.
+- The `Bcc` header field is no longer sent. It is far more simpler and
+efficient: the same message is sent to all recipients instead of sending a
+different email to each Bcc address.
+- LoginAuth has been removed. `NewPlainDialer` now implements the LOGIN
+authentication mechanism when needed.
+- Go 1.2 is now required instead of Go 1.3. No external dependency are used when
+using Go 1.5.
--- a/backend/vendor/gopkg.in/gomail.v2/CONTRIBUTING.md
+++ b/backend/vendor/gopkg.in/gomail.v2/CONTRIBUTING.md
@@ -0,0 +1,20 @@
+Thank you for contributing to Gomail! Here are a few guidelines:
+
+## Bugs
+
+If you think you found a bug, create an issue and supply the minimum amount
+of code triggering the bug so it can be reproduced.
+
+
+## Fixing a bug
+
+If you want to fix a bug, you can send a pull request. It should contains a
+new test or update an existing one to cover that bug.
+
+
+## New feature proposal
+
+If you think Gomail lacks a feature, you can open an issue or send a pull
+request. I want to keep Gomail code and API as simple as possible so please
+describe your needs so we can discuss whether this feature should be added to
+Gomail or not.
--- a/backend/vendor/gopkg.in/gomail.v2/LICENSE
+++ b/backend/vendor/gopkg.in/gomail.v2/LICENSE
@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) 2014 Alexandre Cesaro
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--- a/backend/vendor/gopkg.in/gomail.v2/README.md
+++ b/backend/vendor/gopkg.in/gomail.v2/README.md
@@ -0,0 +1,97 @@
+# Gomail
+[![Build Status](https://travis-ci.org/go-gomail/gomail.svg?branch=v2)](https://travis-ci.org/go-gomail/gomail) [![Code Coverage](http://gocover.io/_badge/gopkg.in/gomail.v2)](http://gocover.io/gopkg.in/gomail.v2) [![Documentation](https://godoc.org/gopkg.in/gomail.v2?status.svg)](https://godoc.org/gopkg.in/gomail.v2)
+
+## Introduction
+
+Gomail is a simple and efficient package to send emails. It is well tested and
+documented.
+
+It is versioned using [gopkg.in](https://gopkg.in) so I promise
+they will never be backward incompatible changes within each version.
+
+It requires Go 1.2 or newer. With Go 1.5, no external dependencies are used.
+
+
+## Features
+
+Gomail supports:
+- Attachments
+- Embedded images
+- HTML and text templates
+- Automatic encoding of special characters
+- SSL and TLS
+- Sending multiple emails with the same SMTP connection
+- Any method to send emails: SMTP, postfix (not included but easily doable), etc
+
+
+## Documentation
+
+https://godoc.org/gopkg.in/gomail.v2
+
+
+## Download
+
+    go get gopkg.in/gomail.v2
+
+
+## Examples
+
+See the [examples in the documentation](https://godoc.org/gopkg.in/gomail.v2#example-package).
+
+
+## FAQ
+
+### x509: certificate signed by unknown authority
+
+If you get this error it means the certificate used by the SMTP server is not
+considered valid by the client running Gomail. As a quick workaround you can
+bypass the verification of the server's certificate chain and host name by using
+`SetTLSConfig`:
+
+    d := gomail.NewPlainDialer("smtp.example.com", "user", "123456", 587)
+    d.TLSConfig = &tls.Config{InsecureSkipVerify: true}
+
+Note, however, that this is insecure and should not be used in production.
+
+
+## Contribute
+
+Contributions are more than welcome! See [CONTRIBUTING.md](CONTRIBUTING.md) for
+more info.
+
+
+## Change log
+
+See [CHANGELOG.md](CHANGELOG.md).
+
+
+## License
+
+[MIT](LICENSE)
+
+
+## Contact
+
+You can ask questions on the [Gomail
+thread](https://groups.google.com/d/topic/golang-nuts/jMxZHzvvEVg/discussion)
+in the Go mailing-list.
+
+
+## Support
+
+If you want to support the development of Gomail, I gladly accept donations.
+
+I will give 100% of the money I receive to
+[Enfants, Espoir Du Monde](http://www.eedm.fr/).
+EEDM is a French NGO which helps children in Bangladesh, Cameroun, Haiti, India
+and Madagascar.
+
+All its members are volunteers so its operating costs are only
+1.9%. So your money will directly helps children of these countries.
+
+As an added bonus, your donations will also tip me by lowering my taxes :smile:
+
+I will send an email with the receipt of the donation to EEDM annually to all
+donors.
+
+[![Donate](https://www.paypalobjects.com/en_US/i/btn/btn_donate_LG.gif)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=PYQKC7VFVXCFG)
--- a/backend/vendor/gopkg.in/gomail.v2/auth.go
+++ b/backend/vendor/gopkg.in/gomail.v2/auth.go
@@ -0,0 +1,67 @@
+package gomail
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"net/smtp"
+)
+
+// plainAuth is an smtp.Auth that implements the PLAIN authentication mechanism.
+// It fallbacks to the LOGIN mechanism if it is the only mechanism advertised
+// by the server.
+type plainAuth struct {
+	username string
+	password string
+	host     string
+	login    bool
+}
+
+func (a *plainAuth) Start(server *smtp.ServerInfo) (string, []byte, error) {
+	if server.Name != a.host {
+		return "", nil, errors.New("gomail: wrong host name")
+	}
+
+	var plain, login bool
+	for _, a := range server.Auth {
+		switch a {
+		case "PLAIN":
+			plain = true
+		case "LOGIN":
+			login = true
+		}
+	}
+
+	if !server.TLS && !plain && !login {
+		return "", nil, errors.New("gomail: unencrypted connection")
+	}
+
+	if !plain && login {
+		a.login = true
+		return "LOGIN", nil, nil
+	}
+
+	return "PLAIN", []byte("\x00" + a.username + "\x00" + a.password), nil
+}
+
+func (a *plainAuth) Next(fromServer []byte, more bool) ([]byte, error) {
+	if !a.login {
+		if more {
+			return nil, errors.New("gomail: unexpected server challenge")
+		}
+		return nil, nil
+	}
+
+	if !more {
+		return nil, nil
+	}
+
+	switch {
+	case bytes.Equal(fromServer, []byte("Username:")):
+		return []byte(a.username), nil
+	case bytes.Equal(fromServer, []byte("Password:")):
+		return []byte(a.password), nil
+	default:
+		return nil, fmt.Errorf("gomail: unexpected server challenge: %s", fromServer)
+	}
+}
--- a/backend/vendor/gopkg.in/gomail.v2/doc.go
+++ b/backend/vendor/gopkg.in/gomail.v2/doc.go
@@ -0,0 +1,5 @@
+// Package gomail provides a simple interface to compose emails and to mail them
+// efficiently.
+//
+// More info on Github: https://github.com/go-gomail/gomail
+package gomail
--- a/backend/vendor/gopkg.in/gomail.v2/message.go
+++ b/backend/vendor/gopkg.in/gomail.v2/message.go
@@ -0,0 +1,302 @@
+package gomail
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// Message represents an email.
+type Message struct {
+	header      header
+	parts       []part
+	attachments []*file
+	embedded    []*file
+	charset     string
+	encoding    Encoding
+	hEncoder    mimeEncoder
+	buf         bytes.Buffer
+}
+
+type header map[string][]string
+
+type part struct {
+	header header
+	copier func(io.Writer) error
+}
+
+// NewMessage creates a new message. It uses UTF-8 and quoted-printable encoding
+// by default.
+func NewMessage(settings ...MessageSetting) *Message {
+	m := &Message{
+		header:   make(header),
+		charset:  "UTF-8",
+		encoding: QuotedPrintable,
+	}
+
+	m.applySettings(settings)
+
+	if m.encoding == Base64 {
+		m.hEncoder = bEncoding
+	} else {
+		m.hEncoder = qEncoding
+	}
+
+	return m
+}
+
+// Reset resets the message so it can be reused. The message keeps its previous
+// settings so it is in the same state that after a call to NewMessage.
+func (m *Message) Reset() {
+	for k := range m.header {
+		delete(m.header, k)
+	}
+	m.parts = nil
+	m.attachments = nil
+	m.embedded = nil
+}
+
+func (m *Message) applySettings(settings []MessageSetting) {
+	for _, s := range settings {
+		s(m)
+	}
+}
+
+// A MessageSetting can be used as an argument in NewMessage to configure an
+// email.
+type MessageSetting func(m *Message)
+
+// SetCharset is a message setting to set the charset of the email.
+func SetCharset(charset string) MessageSetting {
+	return func(m *Message) {
+		m.charset = charset
+	}
+}
+
+// SetEncoding is a message setting to set the encoding of the email.
+func SetEncoding(enc Encoding) MessageSetting {
+	return func(m *Message) {
+		m.encoding = enc
+	}
+}
+
+// Encoding represents a MIME encoding scheme like quoted-printable or base64.
+type Encoding string
+
+const (
+	// QuotedPrintable represents the quoted-printable encoding as defined in
+	// RFC 2045.
+	QuotedPrintable Encoding = "quoted-printable"
+	// Base64 represents the base64 encoding as defined in RFC 2045.
+	Base64 Encoding = "base64"
+	// Unencoded can be used to avoid encoding the body of an email. The headers
+	// will still be encoded using quoted-printable encoding.
+	Unencoded Encoding = "8bit"
+)
+
+// SetHeader sets a value to the given header field.
+func (m *Message) SetHeader(field string, value ...string) {
+	m.encodeHeader(value)
+	m.header[field] = value
+}
+
+func (m *Message) encodeHeader(values []string) {
+	for i := range values {
+		values[i] = m.encodeString(values[i])
+	}
+}
+
+func (m *Message) encodeString(value string) string {
+	return m.hEncoder.Encode(m.charset, value)
+}
+
+// SetHeaders sets the message headers.
+func (m *Message) SetHeaders(h map[string][]string) {
+	for k, v := range h {
+		m.SetHeader(k, v...)
+	}
+}
+
+// SetAddressHeader sets an address to the given header field.
+func (m *Message) SetAddressHeader(field, address, name string) {
+	m.header[field] = []string{m.FormatAddress(address, name)}
+}
+
+// FormatAddress formats an address and a name as a valid RFC 5322 address.
+func (m *Message) FormatAddress(address, name string) string {
+	enc := m.encodeString(name)
+	if enc == name {
+		m.buf.WriteByte('"')
+		for i := 0; i < len(name); i++ {
+			b := name[i]
+			if b == '\\' || b == '"' {
+				m.buf.WriteByte('\\')
+			}
+			m.buf.WriteByte(b)
+		}
+		m.buf.WriteByte('"')
+	} else if hasSpecials(name) {
+		m.buf.WriteString(bEncoding.Encode(m.charset, name))
+	} else {
+		m.buf.WriteString(enc)
+	}
+	m.buf.WriteString(" <")
+	m.buf.WriteString(address)
+	m.buf.WriteByte('>')
+
+	addr := m.buf.String()
+	m.buf.Reset()
+	return addr
+}
+
+func hasSpecials(text string) bool {
+	for i := 0; i < len(text); i++ {
+		switch c := text[i]; c {
+		case '(', ')', '<', '>', '[', ']', ':', ';', '@', '\\', ',', '.', '"':
+			return true
+		}
+	}
+
+	return false
+}
+
+// SetDateHeader sets a date to the given header field.
+func (m *Message) SetDateHeader(field string, date time.Time) {
+	m.header[field] = []string{m.FormatDate(date)}
+}
+
+// FormatDate formats a date as a valid RFC 5322 date.
+func (m *Message) FormatDate(date time.Time) string {
+	return date.Format(time.RFC1123Z)
+}
+
+// GetHeader gets a header field.
+func (m *Message) GetHeader(field string) []string {
+	return m.header[field]
+}
+
+// SetBody sets the body of the message.
+func (m *Message) SetBody(contentType, body string) {
+	m.parts = []part{
+		{
+			header: m.getPartHeader(contentType),
+			copier: func(w io.Writer) error {
+				_, err := io.WriteString(w, body)
+				return err
+			},
+		},
+	}
+}
+
+// AddAlternative adds an alternative part to the message.
+//
+// It is commonly used to send HTML emails that default to the plain text
+// version for backward compatibility.
+//
+// More info: http://en.wikipedia.org/wiki/MIME#Alternative
+func (m *Message) AddAlternative(contentType, body string) {
+	m.parts = append(m.parts,
+		part{
+			header: m.getPartHeader(contentType),
+			copier: func(w io.Writer) error {
+				_, err := io.WriteString(w, body)
+				return err
+			},
+		},
+	)
+}
+
+// AddAlternativeWriter adds an alternative part to the message. It can be
+// useful with the text/template or html/template packages.
+func (m *Message) AddAlternativeWriter(contentType string, f func(io.Writer) error) {
+	m.parts = []part{
+		{
+			header: m.getPartHeader(contentType),
+			copier: f,
+		},
+	}
+}
+
+func (m *Message) getPartHeader(contentType string) header {
+	return map[string][]string{
+		"Content-Type":              {contentType + "; charset=" + m.charset},
+		"Content-Transfer-Encoding": {string(m.encoding)},
+	}
+}
+
+type file struct {
+	Name     string
+	Header   map[string][]string
+	CopyFunc func(w io.Writer) error
+}
+
+func (f *file) setHeader(field, value string) {
+	f.Header[field] = []string{value}
+}
+
+// A FileSetting can be used as an argument in Message.Attach or Message.Embed.
+type FileSetting func(*file)
+
+// SetHeader is a file setting to set the MIME header of the message part that
+// contains the file content.
+//
+// Mandatory headers are automatically added if they are not set when sending
+// the email.
+func SetHeader(h map[string][]string) FileSetting {
+	return func(f *file) {
+		for k, v := range h {
+			f.Header[k] = v
+		}
+	}
+}
+
+// SetCopyFunc is a file setting to replace the function that runs when the
+// message is sent. It should copy the content of the file to the io.Writer.
+//
+// The default copy function opens the file with the given filename, and copy
+// its content to the io.Writer.
+func SetCopyFunc(f func(io.Writer) error) FileSetting {
+	return func(fi *file) {
+		fi.CopyFunc = f
+	}
+}
+
+func (m *Message) appendFile(list []*file, name string, settings []FileSetting) []*file {
+	f := &file{
+		Name:   filepath.Base(name),
+		Header: make(map[string][]string),
+		CopyFunc: func(w io.Writer) error {
+			h, err := os.Open(name)
+			if err != nil {
+				return err
+			}
+			if _, err := io.Copy(w, h); err != nil {
+				h.Close()
+				return err
+			}
+			return h.Close()
+		},
+	}
+
+	for _, s := range settings {
+		s(f)
+	}
+
+	if list == nil {
+		return []*file{f}
+	}
+
+	return append(list, f)
+}
+
+// Attach attaches the files to the email.
+func (m *Message) Attach(filename string, settings ...FileSetting) {
+	m.attachments = m.appendFile(m.attachments, filename, settings)
+}
+
+// Embed embeds the images to the email.
+func (m *Message) Embed(filename string, settings ...FileSetting) {
+	m.embedded = m.appendFile(m.embedded, filename, settings)
+}
--- a/backend/vendor/gopkg.in/gomail.v2/mime.go
+++ b/backend/vendor/gopkg.in/gomail.v2/mime.go
@@ -0,0 +1,19 @@
+// +build go1.5
+
+package gomail
+
+import (
+	"mime"
+	"mime/quotedprintable"
+)
+
+var newQPWriter = quotedprintable.NewWriter
+
+type mimeEncoder struct {
+	mime.WordEncoder
+}
+
+var (
+	bEncoding = mimeEncoder{mime.BEncoding}
+	qEncoding = mimeEncoder{mime.QEncoding}
+)
--- a/backend/vendor/gopkg.in/gomail.v2/mime_go14.go
+++ b/backend/vendor/gopkg.in/gomail.v2/mime_go14.go
@@ -0,0 +1,16 @@
+// +build !go1.5
+
+package gomail
+
+import "gopkg.in/alexcesaro/quotedprintable.v3"
+
+var newQPWriter = quotedprintable.NewWriter
+
+type mimeEncoder struct {
+	quotedprintable.WordEncoder
+}
+
+var (
+	bEncoding = mimeEncoder{quotedprintable.BEncoding}
+	qEncoding = mimeEncoder{quotedprintable.QEncoding}
+)
--- a/backend/vendor/gopkg.in/gomail.v2/send.go
+++ b/backend/vendor/gopkg.in/gomail.v2/send.go
@@ -0,0 +1,117 @@
+package gomail
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/mail"
+)
+
+// Sender is the interface that wraps the Send method.
+//
+// Send sends an email to the given addresses.
+type Sender interface {
+	Send(from string, to []string, msg io.WriterTo) error
+}
+
+// SendCloser is the interface that groups the Send and Close methods.
+type SendCloser interface {
+	Sender
+	Close() error
+}
+
+// A SendFunc is a function that sends emails to the given adresses.
+//
+// The SendFunc type is an adapter to allow the use of ordinary functions as
+// email senders. If f is a function with the appropriate signature, SendFunc(f)
+// is a Sender object that calls f.
+type SendFunc func(from string, to []string, msg io.WriterTo) error
+
+// Send calls f(from, to, msg).
+func (f SendFunc) Send(from string, to []string, msg io.WriterTo) error {
+	return f(from, to, msg)
+}
+
+// Send sends emails using the given Sender.
+func Send(s Sender, msg ...*Message) error {
+	for i, m := range msg {
+		if err := send(s, m); err != nil {
+			return fmt.Errorf("gomail: could not send email %d: %v", i+1, err)
+		}
+	}
+
+	return nil
+}
+
+func send(s Sender, m *Message) error {
+	from, err := m.getFrom()
+	if err != nil {
+		return err
+	}
+
+	to, err := m.getRecipients()
+	if err != nil {
+		return err
+	}
+
+	if err := s.Send(from, to, m); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (m *Message) getFrom() (string, error) {
+	from := m.header["Sender"]
+	if len(from) == 0 {
+		from = m.header["From"]
+		if len(from) == 0 {
+			return "", errors.New(`gomail: invalid message, "From" field is absent`)
+		}
+	}
+
+	return parseAddress(from[0])
+}
+
+func (m *Message) getRecipients() ([]string, error) {
+	n := 0
+	for _, field := range []string{"To", "Cc", "Bcc"} {
+		if addresses, ok := m.header[field]; ok {
+			n += len(addresses)
+		}
+	}
+	list := make([]string, 0, n)
+
+	for _, field := range []string{"To", "Cc", "Bcc"} {
+		if addresses, ok := m.header[field]; ok {
+			for _, a := range addresses {
+				addr, err := parseAddress(a)
+				if err != nil {
+					return nil, err
+				}
+				list = addAddress(list, addr)
+			}
+		}
+	}
+
+	return list, nil
+}
+
+func addAddress(list []string, addr string) []string {
+	for _, a := range list {
+		if addr == a {
+			return list
+		}
+	}
+
+	return append(list, addr)
+}
+
+func parseAddress(field string) (string, error) {
+	a, err := mail.ParseAddress(field)
+	if a == nil {
+		return "", err
+	}
+
+	return a.Address, err
+}
--- a/backend/vendor/gopkg.in/gomail.v2/smtp.go
+++ b/backend/vendor/gopkg.in/gomail.v2/smtp.go
@@ -0,0 +1,175 @@
+package gomail
+
+import (
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net"
+	"net/smtp"
+)
+
+// A Dialer is a dialer to an SMTP server.
+type Dialer struct {
+	// Host represents the host of the SMTP server.
+	Host string
+	// Port represents the port of the SMTP server.
+	Port int
+	// Auth represents the authentication mechanism used to authenticate to the
+	// SMTP server.
+	Auth smtp.Auth
+	// SSL defines whether an SSL connection is used. It should be false in
+	// most cases since the authentication mechanism should use the STARTTLS
+	// extension instead.
+	SSL bool
+	// TSLConfig represents the TLS configuration used for the TLS (when the
+	// STARTTLS extension is used) or SSL connection.
+	TLSConfig *tls.Config
+}
+
+// NewPlainDialer returns a Dialer. The given parameters are used to connect to
+// the SMTP server via a PLAIN authentication mechanism.
+//
+// It fallbacks to the LOGIN mechanism if it is the only mechanism advertised by
+// the server.
+func NewPlainDialer(host string, port int, username, password string) *Dialer {
+	return &Dialer{
+		Host: host,
+		Port: port,
+		Auth: &plainAuth{
+			username: username,
+			password: password,
+			host:     host,
+		},
+		SSL: port == 465,
+	}
+}
+
+// Dial dials and authenticates to an SMTP server. The returned SendCloser
+// should be closed when done using it.
+func (d *Dialer) Dial() (SendCloser, error) {
+	c, err := d.dial()
+	if err != nil {
+		return nil, err
+	}
+
+	if d.Auth != nil {
+		if ok, _ := c.Extension("AUTH"); ok {
+			if err = c.Auth(d.Auth); err != nil {
+				c.Close()
+				return nil, err
+			}
+		}
+	}
+
+	return &smtpSender{c}, nil
+}
+
+func (d *Dialer) dial() (smtpClient, error) {
+	if d.SSL {
+		return d.sslDial()
+	}
+	return d.starttlsDial()
+}
+
+func (d *Dialer) starttlsDial() (smtpClient, error) {
+	c, err := smtpDial(addr(d.Host, d.Port))
+	if err != nil {
+		return nil, err
+	}
+
+	if ok, _ := c.Extension("STARTTLS"); ok {
+		if err := c.StartTLS(d.tlsConfig()); err != nil {
+			c.Close()
+			return nil, err
+		}
+	}
+
+	return c, nil
+}
+
+func (d *Dialer) sslDial() (smtpClient, error) {
+	conn, err := tlsDial("tcp", addr(d.Host, d.Port), d.tlsConfig())
+	if err != nil {
+		return nil, err
+	}
+
+	return newClient(conn, d.Host)
+}
+
+func (d *Dialer) tlsConfig() *tls.Config {
+	if d.TLSConfig == nil {
+		return &tls.Config{ServerName: d.Host}
+	}
+
+	return d.TLSConfig
+}
+
+func addr(host string, port int) string {
+	return fmt.Sprintf("%s:%d", host, port)
+}
+
+// DialAndSend opens a connection to the SMTP server, sends the given emails and
+// closes the connection.
+func (d *Dialer) DialAndSend(m ...*Message) error {
+	s, err := d.Dial()
+	if err != nil {
+		return err
+	}
+	defer s.Close()
+
+	return Send(s, m...)
+}
+
+type smtpSender struct {
+	smtpClient
+}
+
+func (c *smtpSender) Send(from string, to []string, msg io.WriterTo) error {
+	if err := c.Mail(from); err != nil {
+		return err
+	}
+
+	for _, addr := range to {
+		if err := c.Rcpt(addr); err != nil {
+			return err
+		}
+	}
+
+	w, err := c.Data()
+	if err != nil {
+		return err
+	}
+
+	if _, err = msg.WriteTo(w); err != nil {
+		w.Close()
+		return err
+	}
+
+	return w.Close()
+}
+
+func (c *smtpSender) Close() error {
+	return c.Quit()
+}
+
+// Stubbed out for tests.
+var (
+	smtpDial = func(addr string) (smtpClient, error) {
+		return smtp.Dial(addr)
+	}
+	tlsDial   = tls.Dial
+	newClient = func(conn net.Conn, host string) (smtpClient, error) {
+		return smtp.NewClient(conn, host)
+	}
+)
+
+type smtpClient interface {
+	Extension(string) (bool, string)
+	StartTLS(*tls.Config) error
+	Auth(smtp.Auth) error
+	Mail(string) error
+	Rcpt(string) error
+	Data() (io.WriteCloser, error)
+	Quit() error
+	Close() error
+}
--- a/backend/vendor/gopkg.in/gomail.v2/writeto.go
+++ b/backend/vendor/gopkg.in/gomail.v2/writeto.go
@@ -0,0 +1,242 @@
+package gomail
+
+import (
+	"encoding/base64"
+	"errors"
+	"io"
+	"mime"
+	"mime/multipart"
+	"path/filepath"
+	"time"
+)
+
+// WriteTo implements io.WriterTo. It dumps the whole message into w.
+func (m *Message) WriteTo(w io.Writer) (int64, error) {
+	mw := &messageWriter{w: w}
+	mw.writeMessage(m)
+	return mw.n, mw.err
+}
+
+func (w *messageWriter) writeMessage(m *Message) {
+	if _, ok := m.header["Mime-Version"]; !ok {
+		w.writeString("Mime-Version: 1.0\r\n")
+	}
+	if _, ok := m.header["Date"]; !ok {
+		w.writeHeader("Date", m.FormatDate(now()))
+	}
+	w.writeHeaders(m.header)
+
+	if m.hasMixedPart() {
+		w.openMultipart("mixed")
+	}
+
+	if m.hasRelatedPart() {
+		w.openMultipart("related")
+	}
+
+	if m.hasAlternativePart() {
+		w.openMultipart("alternative")
+	}
+	for _, part := range m.parts {
+		w.writeHeaders(part.header)
+		w.writeBody(part.copier, m.encoding)
+	}
+	if m.hasAlternativePart() {
+		w.closeMultipart()
+	}
+
+	w.addFiles(m.embedded, false)
+	if m.hasRelatedPart() {
+		w.closeMultipart()
+	}
+
+	w.addFiles(m.attachments, true)
+	if m.hasMixedPart() {
+		w.closeMultipart()
+	}
+}
+
+func (m *Message) hasMixedPart() bool {
+	return (len(m.parts) > 0 && len(m.attachments) > 0) || len(m.attachments) > 1
+}
+
+func (m *Message) hasRelatedPart() bool {
+	return (len(m.parts) > 0 && len(m.embedded) > 0) || len(m.embedded) > 1
+}
+
+func (m *Message) hasAlternativePart() bool {
+	return len(m.parts) > 1
+}
+
+type messageWriter struct {
+	w          io.Writer
+	n          int64
+	writers    [3]*multipart.Writer
+	partWriter io.Writer
+	depth      uint8
+	err        error
+}
+
+func (w *messageWriter) openMultipart(mimeType string) {
+	mw := multipart.NewWriter(w)
+	contentType := "multipart/" + mimeType + "; boundary=" + mw.Boundary()
+	w.writers[w.depth] = mw
+
+	if w.depth == 0 {
+		w.writeHeader("Content-Type", contentType)
+		w.writeString("\r\n")
+	} else {
+		w.createPart(map[string][]string{
+			"Content-Type": {contentType},
+		})
+	}
+	w.depth++
+}
+
+func (w *messageWriter) createPart(h map[string][]string) {
+	w.partWriter, w.err = w.writers[w.depth-1].CreatePart(h)
+}
+
+func (w *messageWriter) closeMultipart() {
+	if w.depth > 0 {
+		w.writers[w.depth-1].Close()
+		w.depth--
+	}
+}
+
+func (w *messageWriter) addFiles(files []*file, isAttachment bool) {
+	for _, f := range files {
+		if _, ok := f.Header["Content-Type"]; !ok {
+			mediaType := mime.TypeByExtension(filepath.Ext(f.Name))
+			if mediaType == "" {
+				mediaType = "application/octet-stream"
+			}
+			f.setHeader("Content-Type", mediaType+`; name="`+f.Name+`"`)
+		}
+
+		if _, ok := f.Header["Content-Transfer-Encoding"]; !ok {
+			f.setHeader("Content-Transfer-Encoding", string(Base64))
+		}
+
+		if _, ok := f.Header["Content-Disposition"]; !ok {
+			var disp string
+			if isAttachment {
+				disp = "attachment"
+			} else {
+				disp = "inline"
+			}
+			f.setHeader("Content-Disposition", disp+`; filename="`+f.Name+`"`)
+		}
+
+		if !isAttachment {
+			if _, ok := f.Header["Content-ID"]; !ok {
+				f.setHeader("Content-ID", "<"+f.Name+">")
+			}
+		}
+		w.writeHeaders(f.Header)
+		w.writeBody(f.CopyFunc, Base64)
+	}
+}
+
+func (w *messageWriter) Write(p []byte) (int, error) {
+	if w.err != nil {
+		return 0, errors.New("gomail: cannot write as writer is in error")
+	}
+
+	var n int
+	n, w.err = w.w.Write(p)
+	w.n += int64(n)
+	return n, w.err
+}
+
+func (w *messageWriter) writeString(s string) {
+	n, _ := io.WriteString(w.w, s)
+	w.n += int64(n)
+}
+
+func (w *messageWriter) writeStrings(a []string, sep string) {
+	if len(a) > 0 {
+		w.writeString(a[0])
+		if len(a) == 1 {
+			return
+		}
+	}
+	for _, s := range a[1:] {
+		w.writeString(sep)
+		w.writeString(s)
+	}
+}
+
+func (w *messageWriter) writeHeader(k string, v ...string) {
+	w.writeString(k)
+	w.writeString(": ")
+	w.writeStrings(v, ", ")
+	w.writeString("\r\n")
+}
+
+func (w *messageWriter) writeHeaders(h map[string][]string) {
+	if w.depth == 0 {
+		for k, v := range h {
+			if k != "Bcc" {
+				w.writeHeader(k, v...)
+			}
+		}
+	} else {
+		w.createPart(h)
+	}
+}
+
+func (w *messageWriter) writeBody(f func(io.Writer) error, enc Encoding) {
+	var subWriter io.Writer
+	if w.depth == 0 {
+		w.writeString("\r\n")
+		subWriter = w.w
+	} else {
+		subWriter = w.partWriter
+	}
+
+	if enc == Base64 {
+		wc := base64.NewEncoder(base64.StdEncoding, newBase64LineWriter(subWriter))
+		w.err = f(wc)
+		wc.Close()
+	} else if enc == Unencoded {
+		w.err = f(subWriter)
+	} else {
+		wc := newQPWriter(subWriter)
+		w.err = f(wc)
+		wc.Close()
+	}
+}
+
+// As required by RFC 2045, 6.7. (page 21) for quoted-printable, and
+// RFC 2045, 6.8. (page 25) for base64.
+const maxLineLen = 76
+
+// base64LineWriter limits text encoded in base64 to 76 characters per line
+type base64LineWriter struct {
+	w       io.Writer
+	lineLen int
+}
+
+func newBase64LineWriter(w io.Writer) *base64LineWriter {
+	return &base64LineWriter{w: w}
+}
+
+func (w *base64LineWriter) Write(p []byte) (int, error) {
+	n := 0
+	for len(p)+w.lineLen > maxLineLen {
+		w.w.Write(p[:maxLineLen-w.lineLen])
+		w.w.Write([]byte("\r\n"))
+		p = p[maxLineLen-w.lineLen:]
+		n += maxLineLen - w.lineLen
+		w.lineLen = 0
+	}
+
+	w.w.Write(p)
+	w.lineLen += len(p)
+
+	return n + len(p), nil
+}
+
+// Stubbed out for testing.
+var now = time.Now