Decode cf protected email, step 2, Resolve #1102

app/src/main/java/com/hippo/ehviewer/client/EhEngine.kt

@@ -55,12 +55,14 @@ import okhttp3.MediaType.Companion.toMediaType
 import okhttp3.MultipartBody
 import okhttp3.Request
 import okhttp3.RequestBody.Companion.asRequestBody
+import okio.ByteString.Companion.decodeHex
 import org.json.JSONArray
 import org.jsoup.Jsoup
 import org.jsoup.nodes.Element
 import org.jsoup.nodes.TextNode
 import java.io.File
 import java.util.function.Consumer
+import kotlin.experimental.xor
 import kotlin.math.ceil
 
 private const val TAG = "EhEngine"
@@ -129,11 +131,13 @@ private fun resolveEmailProtected(origin: String): String {
         if (EMAIL_PROTECTED in text()) {
             if (EMAIL_PROTECTED in ownText()) {
                 forEachNode(
-                    Consumer {
-                        if (it is TextNode) {
-                            if (EMAIL_PROTECTED in it.text()) {
-                                val encoded = attr("data-cfemail")
-                                resolvedEmailList.add(encoded)
+                    Consumer { node ->
+                        if (node is TextNode) {
+                            if (EMAIL_PROTECTED in node.text()) {
+                                val encoded = attr("data-cfemail").chunked(2).toMutableList()
+                                val k = encoded.removeFirst().decodeHex()[0]
+                                val email = encoded.map { it.decodeHex()[0] xor k }.fold("") { s, c -> s + c.toInt().toChar() }
+                                resolvedEmailList.add(email)
                             }
                         }
                     },