fix: doh

Author: cssxsh

src/main/kotlin/io/github/gnuf0rce/github/GitHubClient.kt

@@ -23,9 +23,6 @@ import io.ktor.client.plugins.contentnegotiation.*
 import io.ktor.client.request.*
 import io.ktor.serialization.kotlinx.json.*
 import kotlinx.coroutines.*
-import okhttp3.HttpUrl.Companion.toHttpUrl
-import okhttp3.OkHttpClient
-import okhttp3.dnsoverhttps.DnsOverHttps
 import java.io.*
 import java.net.*
 import kotlin.coroutines.*
@@ -93,14 +90,7 @@ public open class GitHubClient(public open val token: String?) : CoroutineScope,
         engine {
             config {
                 proxy(this@GitHubClient.proxy)
-                if (doh.isNotEmpty()) {
-                    dns(DnsOverHttps.Builder()
-                        .client(OkHttpClient())
-                        .url(doh.toHttpUrl())
-                        .includeIPv6(ipv6)
-                        .build()
-                    )
-                }
+                doh(urlString = this@GitHubClient.doh, ipv6 = this@GitHubClient.ipv6)
             }
         }
     }

src/main/kotlin/io/github/gnuf0rce/github/OkHttpDnsOverHttps.kt

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2021-2023 dsstudio Technologies and contributors.
+ *
+ *  此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
+ *  Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
+ *
+ *  https://github.com/gnuf0rce/github-helper/blob/master/LICENSE
+ */
+
+
+package io.github.gnuf0rce.github
+
+import okhttp3.Dns
+import okhttp3.HttpUrl.Companion.toHttpUrl
+import okhttp3.OkHttpClient
+import okhttp3.dnsoverhttps.DnsOverHttps
+import java.net.*
+
+internal fun OkHttpClient.Builder.doh(urlString: String, ipv6: Boolean) {
+    if (urlString.isEmpty()) return
+    val doh = DnsOverHttps.Builder()
+        .client(OkHttpClient())
+        .url(urlString.toHttpUrl())
+        .includeIPv6(ipv6)
+        .build()
+    dns(dns = object : Dns {
+        override fun lookup(hostname: String): List<InetAddress> {
+            return try {
+                doh.lookup(hostname)
+            } catch (_: UnknownHostException) {
+                Dns.SYSTEM.lookup(hostname)
+            }
+        }
+    })
+}