323 lines
8 KiB
Go
323 lines
8 KiB
Go
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package gomail
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import (
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"bytes"
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"io"
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"os"
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"path/filepath"
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"time"
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)
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// Message represents an email.
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type Message struct {
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header header
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parts []*part
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attachments []*file
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embedded []*file
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charset string
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encoding Encoding
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hEncoder mimeEncoder
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buf bytes.Buffer
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}
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type header map[string][]string
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type part struct {
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contentType string
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copier func(io.Writer) error
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encoding Encoding
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}
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// NewMessage creates a new message. It uses UTF-8 and quoted-printable encoding
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// by default.
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func NewMessage(settings ...MessageSetting) *Message {
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m := &Message{
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header: make(header),
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charset: "UTF-8",
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encoding: QuotedPrintable,
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}
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m.applySettings(settings)
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if m.encoding == Base64 {
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m.hEncoder = bEncoding
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} else {
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m.hEncoder = qEncoding
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}
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return m
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}
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// Reset resets the message so it can be reused. The message keeps its previous
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// settings so it is in the same state that after a call to NewMessage.
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func (m *Message) Reset() {
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for k := range m.header {
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delete(m.header, k)
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}
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m.parts = nil
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m.attachments = nil
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m.embedded = nil
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}
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func (m *Message) applySettings(settings []MessageSetting) {
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for _, s := range settings {
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s(m)
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}
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}
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// A MessageSetting can be used as an argument in NewMessage to configure an
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// email.
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type MessageSetting func(m *Message)
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// SetCharset is a message setting to set the charset of the email.
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func SetCharset(charset string) MessageSetting {
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return func(m *Message) {
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m.charset = charset
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}
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}
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// SetEncoding is a message setting to set the encoding of the email.
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func SetEncoding(enc Encoding) MessageSetting {
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return func(m *Message) {
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m.encoding = enc
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}
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}
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// Encoding represents a MIME encoding scheme like quoted-printable or base64.
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type Encoding string
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const (
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// QuotedPrintable represents the quoted-printable encoding as defined in
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// RFC 2045.
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QuotedPrintable Encoding = "quoted-printable"
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// Base64 represents the base64 encoding as defined in RFC 2045.
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Base64 Encoding = "base64"
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// Unencoded can be used to avoid encoding the body of an email. The headers
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// will still be encoded using quoted-printable encoding.
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Unencoded Encoding = "8bit"
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)
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// SetHeader sets a value to the given header field.
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func (m *Message) SetHeader(field string, value ...string) {
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m.encodeHeader(value)
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m.header[field] = value
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}
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func (m *Message) encodeHeader(values []string) {
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for i := range values {
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values[i] = m.encodeString(values[i])
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}
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}
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func (m *Message) encodeString(value string) string {
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return m.hEncoder.Encode(m.charset, value)
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}
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// SetHeaders sets the message headers.
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func (m *Message) SetHeaders(h map[string][]string) {
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for k, v := range h {
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m.SetHeader(k, v...)
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}
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}
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// SetAddressHeader sets an address to the given header field.
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func (m *Message) SetAddressHeader(field, address, name string) {
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m.header[field] = []string{m.FormatAddress(address, name)}
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}
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// FormatAddress formats an address and a name as a valid RFC 5322 address.
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func (m *Message) FormatAddress(address, name string) string {
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if name == "" {
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return address
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}
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enc := m.encodeString(name)
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if enc == name {
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m.buf.WriteByte('"')
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for i := 0; i < len(name); i++ {
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b := name[i]
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if b == '\\' || b == '"' {
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m.buf.WriteByte('\\')
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}
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m.buf.WriteByte(b)
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}
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m.buf.WriteByte('"')
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} else if hasSpecials(name) {
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m.buf.WriteString(bEncoding.Encode(m.charset, name))
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} else {
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m.buf.WriteString(enc)
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}
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m.buf.WriteString(" <")
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m.buf.WriteString(address)
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m.buf.WriteByte('>')
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addr := m.buf.String()
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m.buf.Reset()
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return addr
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}
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func hasSpecials(text string) bool {
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for i := 0; i < len(text); i++ {
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switch c := text[i]; c {
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case '(', ')', '<', '>', '[', ']', ':', ';', '@', '\\', ',', '.', '"':
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return true
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}
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}
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return false
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}
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// SetDateHeader sets a date to the given header field.
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func (m *Message) SetDateHeader(field string, date time.Time) {
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m.header[field] = []string{m.FormatDate(date)}
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}
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// FormatDate formats a date as a valid RFC 5322 date.
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func (m *Message) FormatDate(date time.Time) string {
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return date.Format(time.RFC1123Z)
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}
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// GetHeader gets a header field.
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func (m *Message) GetHeader(field string) []string {
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return m.header[field]
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}
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// SetBody sets the body of the message. It replaces any content previously set
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// by SetBody, AddAlternative or AddAlternativeWriter.
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func (m *Message) SetBody(contentType, body string, settings ...PartSetting) {
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m.parts = []*part{m.newPart(contentType, newCopier(body), settings)}
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}
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// AddAlternative adds an alternative part to the message.
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//
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// It is commonly used to send HTML emails that default to the plain text
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// version for backward compatibility. AddAlternative appends the new part to
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// the end of the message. So the plain text part should be added before the
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// HTML part. See http://en.wikipedia.org/wiki/MIME#Alternative
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func (m *Message) AddAlternative(contentType, body string, settings ...PartSetting) {
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m.AddAlternativeWriter(contentType, newCopier(body), settings...)
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}
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func newCopier(s string) func(io.Writer) error {
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return func(w io.Writer) error {
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_, err := io.WriteString(w, s)
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return err
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}
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}
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// AddAlternativeWriter adds an alternative part to the message. It can be
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// useful with the text/template or html/template packages.
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func (m *Message) AddAlternativeWriter(contentType string, f func(io.Writer) error, settings ...PartSetting) {
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m.parts = append(m.parts, m.newPart(contentType, f, settings))
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}
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func (m *Message) newPart(contentType string, f func(io.Writer) error, settings []PartSetting) *part {
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p := &part{
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contentType: contentType,
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copier: f,
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encoding: m.encoding,
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}
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for _, s := range settings {
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s(p)
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}
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return p
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}
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// A PartSetting can be used as an argument in Message.SetBody,
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// Message.AddAlternative or Message.AddAlternativeWriter to configure the part
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// added to a message.
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type PartSetting func(*part)
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// SetPartEncoding sets the encoding of the part added to the message. By
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// default, parts use the same encoding than the message.
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func SetPartEncoding(e Encoding) PartSetting {
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return PartSetting(func(p *part) {
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p.encoding = e
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})
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}
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type file struct {
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Name string
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Header map[string][]string
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CopyFunc func(w io.Writer) error
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}
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func (f *file) setHeader(field, value string) {
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f.Header[field] = []string{value}
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}
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// A FileSetting can be used as an argument in Message.Attach or Message.Embed.
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type FileSetting func(*file)
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// SetHeader is a file setting to set the MIME header of the message part that
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// contains the file content.
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//
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// Mandatory headers are automatically added if they are not set when sending
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// the email.
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func SetHeader(h map[string][]string) FileSetting {
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return func(f *file) {
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for k, v := range h {
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f.Header[k] = v
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}
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}
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}
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// Rename is a file setting to set the name of the attachment if the name is
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// different than the filename on disk.
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func Rename(name string) FileSetting {
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return func(f *file) {
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f.Name = name
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}
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}
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// SetCopyFunc is a file setting to replace the function that runs when the
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// message is sent. It should copy the content of the file to the io.Writer.
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//
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// The default copy function opens the file with the given filename, and copy
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// its content to the io.Writer.
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func SetCopyFunc(f func(io.Writer) error) FileSetting {
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return func(fi *file) {
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fi.CopyFunc = f
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}
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}
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func (m *Message) appendFile(list []*file, name string, settings []FileSetting) []*file {
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f := &file{
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Name: filepath.Base(name),
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Header: make(map[string][]string),
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CopyFunc: func(w io.Writer) error {
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h, err := os.Open(name)
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if err != nil {
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return err
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}
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if _, err := io.Copy(w, h); err != nil {
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h.Close()
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return err
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}
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return h.Close()
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},
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}
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for _, s := range settings {
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s(f)
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}
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if list == nil {
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return []*file{f}
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}
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return append(list, f)
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}
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// Attach attaches the files to the email.
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func (m *Message) Attach(filename string, settings ...FileSetting) {
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m.attachments = m.appendFile(m.attachments, filename, settings)
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}
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// Embed embeds the images to the email.
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func (m *Message) Embed(filename string, settings ...FileSetting) {
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m.embedded = m.appendFile(m.embedded, filename, settings)
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}
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