Harden scan robustness and tests

plugins/services/smb_protocol_test.go

@@ -0,0 +1,51 @@
+//go:build plugin_smb || !plugin_selective
+
+package services
+
+import (
+	"io"
+	"net"
+	"testing"
+	"time"
+)
+
+type chunkedSMBConn struct {
+	data      []byte
+	chunkSize int
+}
+
+func (c *chunkedSMBConn) Read(p []byte) (int, error) {
+	if len(c.data) == 0 {
+		return 0, io.EOF
+	}
+	n := len(c.data)
+	if c.chunkSize > 0 && n > c.chunkSize {
+		n = c.chunkSize
+	}
+	if n > len(p) {
+		n = len(p)
+	}
+	copy(p, c.data[:n])
+	c.data = c.data[n:]
+	return n, nil
+}
+
+func (c *chunkedSMBConn) Write([]byte) (int, error)       { return 0, nil }
+func (c *chunkedSMBConn) Close() error                    { return nil }
+func (c *chunkedSMBConn) LocalAddr() net.Addr             { return nil }
+func (c *chunkedSMBConn) RemoteAddr() net.Addr            { return nil }
+func (c *chunkedSMBConn) SetDeadline(time.Time) error     { return nil }
+func (c *chunkedSMBConn) SetReadDeadline(time.Time) error { return nil }
+func (c *chunkedSMBConn) SetWriteDeadline(time.Time) error {
+	return nil
+}
+
+func TestReadSMBMessageHandlesChunkedReads(t *testing.T) {
+	got, err := readSMBMessage(&chunkedSMBConn{data: []byte{0, 0, 0, 3, 'S', 'M', 'B'}, chunkSize: 1})
+	if err != nil {
+		t.Fatalf("readSMBMessage() error = %v", err)
+	}
+	if string(got) != "\x00\x00\x00\x03SMB" {
+		t.Fatalf("readSMBMessage() = %q", got)
+	}
+}