add vendoring

vendor/github.com/jhillyerd/enmime/inspect.go

@@ -0,0 +1,74 @@
+package enmime
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"net/textproto"
+
+	"github.com/jhillyerd/enmime/internal/coding"
+	"github.com/pkg/errors"
+)
+
+var defaultHeadersList = []string{
+	"From",
+	"To",
+	"Sender",
+	"CC",
+	"BCC",
+	"Subject",
+	"Date",
+}
+
+// DecodeHeaders returns a limited selection of mime headers for use by user agents
+// Default header list:
+//   "Date", "Subject", "Sender", "From", "To", "CC" and "BCC"
+//
+// Additional headers provided will be formatted canonically:
+//   h, err := enmime.DecodeHeaders(b, "content-type", "user-agent")
+func DecodeHeaders(b []byte, addtlHeaders ...string) (textproto.MIMEHeader, error) {
+	b = ensureHeaderBoundary(b)
+	tr := textproto.NewReader(bufio.NewReader(bytes.NewReader(b)))
+	headers, err := tr.ReadMIMEHeader()
+	switch errors.Cause(err) {
+	case nil, io.EOF:
+	// carry on, io.EOF is expected
+	default:
+		return nil, err
+	}
+	headerList := defaultHeadersList
+	headerList = append(headerList, addtlHeaders...)
+	res := map[string][]string{}
+	for _, header := range headerList {
+		h := textproto.CanonicalMIMEHeaderKey(header)
+		res[h] = make([]string, 0, len(headers[h]))
+		for _, value := range headers[h] {
+			res[h] = append(res[h], coding.RFC2047Decode(value))
+		}
+	}
+
+	return res, nil
+}
+
+// ensureHeaderBoundary scans through an rfc822 document to ensure the boundary between headers and body exists
+func ensureHeaderBoundary(b []byte) []byte {
+	slice := bytes.SplitAfter(b, []byte{'\r', '\n'})
+	dest := make([]byte, 0, len(b)+2)
+	headers := true
+	for _, v := range slice {
+		if headers && (bytes.Contains(v, []byte{':'}) || bytes.HasPrefix(v, []byte{' '}) || bytes.HasPrefix(v, []byte{'\t'})) {
+			dest = append(dest, v...)
+			continue
+		}
+		if headers {
+			headers = false
+			if !bytes.Equal(v, []byte{'\r', '\n'}) {
+				dest = append(dest, append([]byte{'\r', '\n'}, v...)...)
+				continue
+			}
+		}
+		dest = append(dest, v...)
+	}
+
+	return dest
+}