mirror of
https://github.com/wneessen/go-mail.git
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Winni Neessen
47eb7b582b
The error handling in the msgWriter.writeBody() method was not working properly. We basically overwrote the mw.err with nil if the function that followed after a failed write attempt was successful again This patch fixes #81
340 lines
7.8 KiB
Go
340 lines
7.8 KiB
Go
// SPDX-FileCopyrightText: 2022 Winni Neessen <winni@neessen.dev>
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//
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// SPDX-License-Identifier: MIT
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package mail
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import (
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"bytes"
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"encoding/base64"
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"fmt"
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"io"
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"mime"
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"mime/multipart"
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"mime/quotedprintable"
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"net/textproto"
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"path/filepath"
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"sort"
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"strings"
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)
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// MaxHeaderLength defines the maximum line length for a mail header
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// RFC 2047 suggests 76 characters
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const MaxHeaderLength = 76
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// MaxBodyLength defines the maximum line length for the mail body
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// RFC 2047 suggests 76 characters
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const MaxBodyLength = 76
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// SingleNewLine represents a new line that can be used by the msgWriter to issue a carriage return
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const SingleNewLine = "\r\n"
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// DoubleNewLine represents a double new line that can be used by the msgWriter to
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// indicate a new segement of the mail
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const DoubleNewLine = "\r\n\r\n"
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// msgWriter handles the I/O to the io.WriteCloser of the SMTP client
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type msgWriter struct {
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c Charset
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d int8
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en mime.WordEncoder
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err error
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mpw [3]*multipart.Writer
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n int64
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pw io.Writer
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w io.Writer
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}
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// Write implements the io.Writer interface for msgWriter
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func (mw *msgWriter) Write(p []byte) (int, error) {
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if mw.err != nil {
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return 0, fmt.Errorf("failed to write due to previous error: %w", mw.err)
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}
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var n int
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n, mw.err = mw.w.Write(p)
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mw.n += int64(n)
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return n, mw.err
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}
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// writeMsg formats the message and sends it to its io.Writer
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func (mw *msgWriter) writeMsg(m *Msg) {
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m.addDefaultHeader()
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m.checkUserAgent()
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mw.writeGenHeader(m)
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mw.writePreformattedGenHeader(m)
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// Set the FROM header (or envelope FROM if FROM is empty)
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hf := true
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f, ok := m.addrHeader[HeaderFrom]
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if !ok || len(f) == 0 {
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f, ok = m.addrHeader[HeaderEnvelopeFrom]
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if !ok || len(f) == 0 {
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hf = false
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}
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}
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if hf {
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mw.writeHeader(Header(HeaderFrom), f[0].String())
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}
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// Set the rest of the address headers
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for _, t := range []AddrHeader{HeaderTo, HeaderCc} {
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if al, ok := m.addrHeader[t]; ok {
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var v []string
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for _, a := range al {
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v = append(v, a.String())
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}
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mw.writeHeader(Header(t), v...)
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}
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}
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if m.hasMixed() {
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mw.startMP("mixed", m.boundary)
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mw.writeString(DoubleNewLine)
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}
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if m.hasRelated() {
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mw.startMP("related", m.boundary)
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mw.writeString(DoubleNewLine)
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}
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if m.hasAlt() {
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mw.startMP(MIMEAlternative, m.boundary)
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mw.writeString(DoubleNewLine)
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}
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for _, p := range m.parts {
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mw.writePart(p, m.charset)
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}
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if m.hasAlt() {
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mw.stopMP()
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}
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// Add embeds
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mw.addFiles(m.embeds, false)
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if m.hasRelated() {
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mw.stopMP()
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}
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// Add attachments
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mw.addFiles(m.attachments, true)
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if m.hasMixed() {
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mw.stopMP()
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}
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}
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// writeGenHeader writes out all generic headers to the msgWriter
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func (mw *msgWriter) writeGenHeader(m *Msg) {
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gk := make([]string, 0, len(m.genHeader))
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for k := range m.genHeader {
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gk = append(gk, string(k))
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}
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sort.Strings(gk)
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for _, k := range gk {
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mw.writeHeader(Header(k), m.genHeader[Header(k)]...)
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}
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}
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// writePreformatedHeader writes out all preformated generic headers to the msgWriter
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func (mw *msgWriter) writePreformattedGenHeader(m *Msg) {
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for k, v := range m.preformHeader {
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mw.writeString(fmt.Sprintf("%s: %s%s", k, v, SingleNewLine))
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}
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}
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// startMP writes a multipart beginning
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func (mw *msgWriter) startMP(mt MIMEType, b string) {
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mp := multipart.NewWriter(mw)
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if b != "" {
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mw.err = mp.SetBoundary(b)
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}
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ct := fmt.Sprintf("multipart/%s;\r\n boundary=%s", mt, mp.Boundary())
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mw.mpw[mw.d] = mp
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if mw.d == 0 {
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mw.writeString(fmt.Sprintf("%s: %s", HeaderContentType, ct))
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}
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if mw.d > 0 {
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mw.newPart(map[string][]string{"Content-Type": {ct}})
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}
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mw.d++
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}
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// stopMP closes the multipart
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func (mw *msgWriter) stopMP() {
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if mw.d > 0 {
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mw.err = mw.mpw[mw.d-1].Close()
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mw.d--
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}
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}
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// addFiles adds the attachments/embeds file content to the mail body
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func (mw *msgWriter) addFiles(fl []*File, a bool) {
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for _, f := range fl {
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if _, ok := f.getHeader(HeaderContentType); !ok {
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mt := mime.TypeByExtension(filepath.Ext(f.Name))
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if mt == "" {
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mt = "application/octet-stream"
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}
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f.setHeader(HeaderContentType, fmt.Sprintf(`%s; name="%s"`, mt,
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mw.en.Encode(mw.c.String(), f.Name)))
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}
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if _, ok := f.getHeader(HeaderContentTransferEnc); !ok {
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f.setHeader(HeaderContentTransferEnc, string(EncodingB64))
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}
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if _, ok := f.getHeader(HeaderContentDisposition); !ok {
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d := "inline"
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if a {
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d = "attachment"
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}
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f.setHeader(HeaderContentDisposition, fmt.Sprintf(`%s; filename="%s"`, d,
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mw.en.Encode(mw.c.String(), f.Name)))
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}
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if !a {
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if _, ok := f.getHeader(HeaderContentID); !ok {
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f.setHeader(HeaderContentID, fmt.Sprintf("<%s>", f.Name))
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}
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}
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if mw.d == 0 {
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for h, v := range f.Header {
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mw.writeHeader(Header(h), v...)
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}
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mw.writeString(SingleNewLine)
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}
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if mw.d > 0 {
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mw.newPart(f.Header)
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}
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mw.writeBody(f.Writer, EncodingB64)
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}
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}
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// newPart creates a new MIME multipart io.Writer and sets the partwriter to it
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func (mw *msgWriter) newPart(h map[string][]string) {
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mw.pw, mw.err = mw.mpw[mw.d-1].CreatePart(h)
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}
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// writePart writes the corresponding part to the Msg body
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func (mw *msgWriter) writePart(p *Part, cs Charset) {
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ct := fmt.Sprintf("%s; charset=%s", p.ctype, cs)
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cte := p.enc.String()
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if mw.d == 0 {
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mw.writeHeader(HeaderContentType, ct)
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mw.writeHeader(HeaderContentTransferEnc, cte)
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mw.writeString(SingleNewLine)
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}
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if mw.d > 0 {
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mh := textproto.MIMEHeader{}
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mh.Add(string(HeaderContentType), ct)
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mh.Add(string(HeaderContentTransferEnc), cte)
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mw.newPart(mh)
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}
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mw.writeBody(p.w, p.enc)
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}
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// writeString writes a string into the msgWriter's io.Writer interface
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func (mw *msgWriter) writeString(s string) {
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if mw.err != nil {
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return
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}
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var n int
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n, mw.err = io.WriteString(mw.w, s)
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mw.n += int64(n)
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}
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// writeHeader writes a header into the msgWriter's io.Writer
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func (mw *msgWriter) writeHeader(k Header, vl ...string) {
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wbuf := bytes.Buffer{}
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cl := MaxHeaderLength - 2
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wbuf.WriteString(string(k))
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cl -= len(k)
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if len(vl) == 0 {
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wbuf.WriteString(":\r\n")
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return
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}
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wbuf.WriteString(": ")
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cl -= 2
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fs := strings.Join(vl, ", ")
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sfs := strings.Split(fs, " ")
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for i, v := range sfs {
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if cl-len(v) <= 1 {
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wbuf.WriteString(fmt.Sprintf("%s ", SingleNewLine))
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cl = MaxHeaderLength - 3
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}
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wbuf.WriteString(v)
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if i < len(sfs)-1 {
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wbuf.WriteString(" ")
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cl -= 1
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}
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cl -= len(v)
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}
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bufs := wbuf.String()
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bufs = strings.ReplaceAll(bufs, fmt.Sprintf(" %s", SingleNewLine), SingleNewLine)
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mw.writeString(bufs)
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mw.writeString("\r\n")
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}
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// writeBody writes an io.Reader into an io.Writer using provided Encoding
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func (mw *msgWriter) writeBody(f func(io.Writer) (int64, error), e Encoding) {
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var w io.Writer
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var ew io.WriteCloser
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var n int64
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var err error
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if mw.d == 0 {
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w = mw.w
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}
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if mw.d > 0 {
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w = mw.pw
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}
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wbuf := bytes.Buffer{}
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lb := Base64LineBreaker{}
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lb.out = &wbuf
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switch e {
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case EncodingQP:
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ew = quotedprintable.NewWriter(&wbuf)
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case EncodingB64:
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ew = base64.NewEncoder(base64.StdEncoding, &lb)
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case NoEncoding:
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_, err = f(&wbuf)
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if err != nil {
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mw.err = fmt.Errorf("bodyWriter function: %w", err)
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}
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n, err = io.Copy(w, &wbuf)
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if err != nil && mw.err == nil {
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mw.err = fmt.Errorf("bodyWriter io.Copy: %w", err)
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}
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if mw.d == 0 {
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mw.n += n
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}
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return
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default:
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ew = quotedprintable.NewWriter(w)
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}
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_, err = f(ew)
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if err != nil {
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mw.err = fmt.Errorf("bodyWriter function: %w", err)
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}
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err = ew.Close()
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if err != nil && mw.err == nil {
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mw.err = fmt.Errorf("bodyWriter close encoded writer: %w", err)
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}
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err = lb.Close()
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if err != nil && mw.err == nil {
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mw.err = fmt.Errorf("bodyWriter close linebreaker: %w", err)
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}
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n, err = io.Copy(w, &wbuf)
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if err != nil && mw.err == nil {
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mw.err = fmt.Errorf("bodyWriter io.Copy: %w", err)
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}
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// Since the part writer uses the WriteTo() method, we don't need to add the
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// bytes twice
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if mw.d == 0 {
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mw.n += n
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}
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}
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