// Learned from net.textproto. One difference is that this one keeps the
// ending '\n' in the returned line. Buf if there's only CRLF in the line,
// return nil for the line.
func readContinuedLineSlice(r *bufio.Reader) ([]byte, error) {
// feedly.com request headers contains things like:
// "$Authorization.feedly: $FeedlyAuth\r\n", so we must test for only
// continuation spaces.
isspace := func(b byte) bool {
return b == ' ' || b == '\t'
}
// Read the first line.
line, err := r.ReadSlice('\n')
if err != nil {
return nil, err
}
// There are servers that use \n for line ending, so trim first before check ending.
// For example, the 404 page for http://plan9.bell-labs.com/magic/man2html/1/2l
trimmed := TrimSpace(line)
if len(trimmed) == 0 {
if len(line) > 2 {
return nil, fmt.Errorf("malformed end of headers, len: %d, %#v", len(line), string(line))
}
return nil, nil
}
if isspace(line[0]) {
return nil, fmt.Errorf("malformed header, start with space: %#v", string(line))
}
// Optimistically assume that we have started to buffer the next line
// and it starts with an ASCII letter (the next header key), so we can
// avoid copying that buffered data around in memory and skipping over
// non-existent whitespace.
if r.Buffered() > 0 {
peek, err := r.Peek(1)
if err == nil && !isspace(peek[0]) {
return line, nil
}
}
var buf []byte
buf = append(buf, trimmed...)
// Read continuation lines.
for skipSpace(r) > 0 {
line, err := r.ReadSlice('\n')
if err != nil {
break
}
buf = append(buf, ' ')
buf = append(buf, TrimTrailingSpace(line)...)
}
buf = append(buf, '\r', '\n')
return buf, nil
}
