Add cdp support for xpath scrapers (#625)

Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

vendor/github.com/gobwas/ws/cipher.go

@@ -0,0 +1,56 @@
+package ws
+
+import (
+	"unsafe"
+)
+
+// Cipher applies XOR cipher to the payload using mask.
+// Offset is used to cipher chunked data (e.g. in io.Reader implementations).
+//
+// To convert masked data into unmasked data, or vice versa, the following
+// algorithm is applied.  The same algorithm applies regardless of the
+// direction of the translation, e.g., the same steps are applied to
+// mask the data as to unmask the data.
+func Cipher(payload []byte, mask [4]byte, offset int) {
+	n := len(payload)
+	if n < 8 {
+		for i := 0; i < n; i++ {
+			payload[i] ^= mask[(offset+i)%4]
+		}
+		return
+	}
+
+	// Calculate position in mask due to previously processed bytes number.
+	mpos := offset % 4
+	// Count number of bytes will processed one by one from the beginning of payload.
+	ln := remain[mpos]
+	// Count number of bytes will processed one by one from the end of payload.
+	// This is done to process payload by 8 bytes in each iteration of main loop.
+	rn := (n - ln) % 8
+
+	for i := 0; i < ln; i++ {
+		payload[i] ^= mask[(mpos+i)%4]
+	}
+	for i := n - rn; i < n; i++ {
+		payload[i] ^= mask[(mpos+i)%4]
+	}
+
+	// We should cast mask to uint32 with unsafe instead of encoding.BigEndian
+	// to avoid care of os dependent byte order. That is, on any endianess mask
+	// and payload will be presented with the same order. In other words, we
+	// could not use encoding.BigEndian on xoring payload as uint64.
+	m := *(*uint32)(unsafe.Pointer(&mask))
+	m2 := uint64(m)<<32 | uint64(m)
+
+	// Skip already processed right part.
+	// Get number of uint64 parts remaining to process.
+	n = (n - ln - rn) >> 3
+	for i := 0; i < n; i++ {
+		v := (*uint64)(unsafe.Pointer(&payload[ln+(i<<3)]))
+		*v = *v ^ m2
+	}
+}
+
+// remain maps position in masking key [0,4) to number
+// of bytes that need to be processed manually inside Cipher().
+var remain = [4]int{0, 3, 2, 1}