Initial QSfera import

Server/vendor/github.com/Azure/go-ntlmssp/varfield.go

@@ -0,0 +1,47 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+package ntlmssp
+
+import (
+	"errors"
+)
+
+type varField struct {
+	Len          uint16
+	MaxLen       uint16
+	BufferOffset uint32
+}
+
+func (f varField) ReadFrom(buffer []byte) ([]byte, error) {
+	// f.Len is controlled by the sender, so we need to check that
+	// it doesn't cause an overflow when added to f.BufferOffset.
+	start := uint64(f.BufferOffset)
+	end := start + uint64(f.Len)
+	if end < start || end > uint64(len(buffer)) {
+		return nil, errors.New("error reading data, varField extends beyond buffer")
+	}
+	return buffer[int(start):int(end)], nil
+}
+
+func (f varField) ReadStringFrom(buffer []byte, unicode bool) (string, error) {
+	d, err := f.ReadFrom(buffer)
+	if err != nil {
+		return "", err
+	}
+	if unicode { // UTF-16LE encoding scheme
+		return fromUnicode(d)
+	}
+	// OEM encoding, close enough to ASCII, since no code page is specified
+	return string(d), err
+}
+
+func newVarField(ptr *int, fieldsize int) varField {
+	f := varField{
+		Len:          uint16(fieldsize),
+		MaxLen:       uint16(fieldsize),
+		BufferOffset: uint32(*ptr),
+	}
+	*ptr += fieldsize
+	return f
+}