/
filters_header.go
334 lines (309 loc) · 8.68 KB
/
filters_header.go
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// Copyright 2017, 2023 The Agostle Authors. All rights reserved.
// Use of this source code is governed by an Apache 2.0
// license that can be found in the LICENSE file.
package converter
import (
"bufio"
"bytes"
"context"
"fmt"
"html/template"
"io"
"net/mail"
"net/textproto"
"os"
"golang.org/x/text/encoding"
"golang.org/x/text/encoding/htmlindex"
"golang.org/x/text/transform"
"github.com/tgulacsi/go/byteutil"
"github.com/tgulacsi/go/i18nmail"
)
// PrependHeaderFilter writes Subject, From... headers at the beginning of the html/plain parts.
func PrependHeaderFilter(ctx context.Context,
inch <-chan i18nmail.MailPart, outch chan<- i18nmail.MailPart,
files chan<- ArchFileItem, errch chan<- error,
) {
logger := getLogger(ctx)
defer func() {
close(outch)
}()
ctx, _ = prepareContext(ctx, "")
mailHeader := mail.Header(make(map[string][]string, len(PrependHeaders)))
headersBuf := bytes.NewBuffer(make([]byte, 0, 128))
for part := range inch {
logger.Debug("PrependHeaderFilter receives", "seq", part.Seq, "ct", part.ContentType, "header", part.Header, "inch", inch)
if len(mailHeader["From"]) == 0 || mailHeader.Get("Subject") == "" {
hdrs := make([]textproto.MIMEHeader, 0, 4)
{
parent := &part
if len(parent.Header) > 0 {
hdrs = append(hdrs, parent.Header)
}
for i := 0; parent.Parent != nil && parent.Parent != parent && i < 10; i++ {
parent = parent.Parent
if len(parent.Header) > 0 {
logger.Debug("parent", "header", parent.Header)
hdrs = append(hdrs, parent.Header)
}
}
}
if len(hdrs) > 0 {
hdr := hdrs[len(hdrs)-1]
logger.Info("filling mailHeader", "header", hdr)
for _, k := range PrependHeaders {
if v, ok := hdr[k]; ok {
mailHeader[k] = v
}
}
}
}
if !(part.ContentType == textPlain || part.ContentType == textHtml) {
goto Skip
}
headersBuf.Reset()
if err := writeHeaders(ctx, headersBuf, mailHeader, part.ContentType); err != nil {
logger.Info("error writing headers", "error", err)
goto Skip
}
//logger.Info("headers written", "buf", headersBuf.String())
if part.ContentType != textHtml {
part.Body, _ = i18nmail.MakeSectionReader(
io.MultiReader(bytes.NewReader(headersBuf.Bytes()), part.Body),
bodyThreshold,
)
goto Skip
}
part.Body, _ = i18nmail.MakeSectionReader(
decodeHTML(ctx, part.Body, *ConfWkhtmltopdf == ""), bodyThreshold)
logger.Debug("PrependHeaderFilter", "wkhtmltopdf", *ConfWkhtmltopdf, "body", part.Body, "threshold", bodyThreshold)
if *ConfWkhtmltopdf == "" {
b, err := io.ReadAll(part.Body)
if err != nil {
logger.Info("cannot read", "body", part.Body, "error", err)
}
// add some garbage to each line ending!
b = bytes.TrimSpace(
bytes.Replace(
bytes.Replace(b, []byte("\r\n"), []byte{'\n'}, -1),
[]byte{'\n'}, []byte("<!-- -->\n"), -1,
))
// change to HTML5
i, _ := tagIndex(b, "head")
if i < 0 {
i, _ = tagIndex(b, "body")
}
// Insert DOCTYPE before <head
if i >= 0 {
const htmlPrefix = "<!DOCTYPE html>\n<html>\n"
if i >= len(htmlPrefix) {
b = b[i-len(htmlPrefix):]
copy(b, []byte(htmlPrefix))
} else {
b = append([]byte(htmlPrefix), b[i:]...)
}
}
if bodyPos, _ := tagIndex(b, "body"); bodyPos >= 0 {
// even more garbage
b = append(append(b[:bodyPos], []byte("<!-- ------ -->")...),
b[bodyPos:]...)
}
if i := bytes.LastIndex(b, []byte("</body>")); i >= 0 {
b = append(b[:i+7], []byte("</html>")...)
} else if bytes.HasSuffix(b, []byte("</html")) {
b = append(b, '>')
} else if bytes.HasSuffix(b, []byte("</htm")) {
b = append(b, 'l', '>')
} else if bytes.HasSuffix(b, []byte("</ht")) {
b = append(b, 'm', 'l', '>')
}
if _, j := tagIndex(b, "body"); j >= 0 {
part.Body, _ = i18nmail.MakeSectionReader(io.MultiReader(
bytes.NewReader(b[:j]),
bytes.NewReader(headersBuf.Bytes()),
bytes.NewReader(b[j:]),
), bodyThreshold)
} else {
part.Body, _ = i18nmail.MakeSectionReader(io.MultiReader(
bytes.NewReader(headersBuf.Bytes()),
bytes.NewReader(b),
), bodyThreshold)
}
} else {
b := make([]byte, 1<<20)
n, _ := io.ReadAtLeast(part.Body, b, len(b)/2)
b = b[:n]
if _, j := tagIndex(b, "body"); j >= 0 {
part.Body, _ = i18nmail.MakeSectionReader(io.MultiReader(
bytes.NewReader(b[:j]),
bytes.NewReader(headersBuf.Bytes()),
bytes.NewReader(b[j:]),
part.Body,
), bodyThreshold)
} else {
c := b
if len(c) > 4096 {
c = c[len(c)-4096:]
}
logger.Info("no body in", "b", string(c))
part.Body, _ = i18nmail.MakeSectionReader(io.MultiReader(
bytes.NewReader(headersBuf.Bytes()),
bytes.NewReader(b),
part.Body,
), bodyThreshold)
}
}
Skip:
outch <- part
}
}
func tagIndex(b []byte, tag string) (int, int) {
i := byteutil.ByteIndexFold(b, []byte("<"+tag))
if i < 0 {
return -1, -1
}
k := i + 1 + len(tag)
j := bytes.IndexByte(b[k:], '>')
if j < 0 {
return -1, -1
}
j += k + 1
return i, j
}
// decodeHTML decodes the HTML's encoding.
func decodeHTML(ctx context.Context, r io.Reader, deleteMETA bool) io.Reader {
b := make([]byte, 4096)
n, _ := io.ReadAtLeast(r, b, len(b)/2)
b = b[:n]
r = io.MultiReader(bytes.NewReader(b), r)
logger := getLogger(ctx)
var enc encoding.Encoding
p := 0
for {
i, j := tagIndex(b[p:], "meta")
if i < 0 {
break
}
i, j = i+p, j+p
p += j + 1
c := b[i:j]
k := byteutil.ByteIndexFold(c, []byte("charset="))
if k < 0 {
continue
}
c = c[k+8:]
if len(c) > 0 && c[0] == '"' { // maybe HTML5 <meta charset="..."/>
c = c[1:]
}
if k = bytes.IndexByte(c, '"'); k < 0 {
continue
}
cs := bytes.TrimSpace(c[:k])
if len(cs) == 0 {
continue
}
charset := string(cs)
if deleteMETA {
// delete the whole <meta .../> part
copy(b[i:j], bytes.Repeat([]byte{' '}, j-i))
}
var err error
if enc, err = htmlindex.Get(charset); err != nil {
logger.Info("cannot find encoding", "charset", charset)
continue
}
if !deleteMETA && len(charset) >= 5 {
copy(c[:5], []byte("utf-8"))
if len(cs) > 5 {
copy(c[5:k], bytes.Repeat([]byte{' '}, k-5))
}
}
break
}
if enc != nil {
return transform.NewReader(r, enc.NewDecoder())
}
return r
}
// PrependHeaders are the headers which should be prepended to the printed mail
var PrependHeaders = []string{"From", "To", "Cc", "Subject", "Date"}
func writeToFile(ctx context.Context, fn string, r io.Reader, contentType string /*, mailHeader mail.Header*/) error {
fh, err := os.Create(fn)
if err != nil {
return fmt.Errorf("create file %s: %w", fn, err)
}
br := bufio.NewReader(r)
logger := getLogger(ctx)
logger.Info("writeToPdfFile", "file", fn, "ct", contentType)
if _, err = io.Copy(fh, br); err != nil {
_ = fh.Close()
return fmt.Errorf("save to %s: %w", fn, err)
}
return fh.Close()
}
func writeHeaders(ctx context.Context, w io.Writer, mailHeader mail.Header, contentType string) error {
logger := getLogger(ctx)
if mailHeader == nil || !(contentType == textPlain || contentType == textHtml) {
return nil
}
var buf bytes.Buffer
ew := &errWriter{Writer: &buf}
var preList, postList, preKey string
postKey, preAddr, postAddr := ": ", "<", ">"
bol, eol := " ", "\r\n"
escape := func(s string) string { return s }
if contentType == textHtml {
preList, postList = "<div><ul>\n", "</ul></div>\n"
preKey, postKey = "<em>", ":</em> "
bol, eol = "<li>", "</li>\n"
preAddr, postAddr = "<", ">"
escape = template.HTMLEscapeString
}
_, _ = io.WriteString(ew, preList)
mh := i18nmail.Header(mailHeader)
for _, k := range PrependHeaders {
if k == "Subject" || k == "Date" {
continue
}
if mh.Get(k) == "" {
continue
}
_, _ = io.WriteString(ew, bol+preKey+k+postKey)
addr, err := mh.AddressList(k)
if err != nil {
if a, err := i18nmail.ParseAddress(mh.Get(k)); err != nil {
logger.Info("parsing address", "of", k, "value", mh.Get(k), "error", err)
_, _ = io.WriteString(ew, escape(mh.Get(k)))
} else {
addr = append(addr, a)
}
}
s := ""
for i, a := range addr {
_, _ = io.WriteString(ew, s+escape(a.Name)+" "+preAddr+escape(a.Address)+postAddr)
if i == 0 {
s = ", "
}
}
_, _ = io.WriteString(ew, eol)
}
_, _ = io.WriteString(ew, bol+preKey+"Subject"+postKey+escape(i18nmail.HeadDecode(mh.Get("Subject")))+eol)
_, _ = io.WriteString(ew, bol+preKey+"Date"+postKey+escape(mh.Get("Date"))+eol)
_, _ = io.WriteString(ew, postList)
if ew.Err != nil {
return ew.Err
}
_, err := w.Write(buf.Bytes())
return err
}
type errWriter struct {
io.Writer
Err error
}
func (ew *errWriter) Write(p []byte) (int, error) {
if ew.Err != nil {
return 0, ew.Err
}
var n int
n, ew.Err = ew.Writer.Write(p)
return n, ew.Err
}