From 2db9e9ee83961204aae2167c1e35f6b4c807c65a Mon Sep 17 00:00:00 2001
From: Shreyas Zare <shreyas@technitium.com>
Date: Sat, 17 Feb 2024 17:22:29 +0530
Subject: [PATCH] AdvancedForwarding: updated adguard upstream implementation
 to support multiple forwarders.

---
 Apps/AdvancedForwardingApp/App.cs             | 49 ++++++++++++++++++-
 .../adguard-upstreams.txt                     |  2 +-
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/Apps/AdvancedForwardingApp/App.cs b/Apps/AdvancedForwardingApp/App.cs
index 58b06bc0..c3044587 100644
--- a/Apps/AdvancedForwardingApp/App.cs
+++ b/Apps/AdvancedForwardingApp/App.cs
@@ -547,6 +547,8 @@ namespace AdvancedForwarding
         {
             #region variables
 
+            static readonly char[] _popWordSeperator = new char[] { ' ' };
+
             readonly IDnsServer _dnsServer;
 
             readonly string _name;
@@ -666,7 +668,28 @@ namespace AdvancedForwarding
                                 }
                                 else
                                 {
-                                    forwardings.Add(new Forwarding(domains, NameServerAddress.Parse(forwarder), _dnssecValidation, _configProxyServer));
+                                    List<DnsForwarderRecordData> forwarderRecords = new List<DnsForwarderRecordData>();
+                                    string word = PopWord(ref forwarder);
+
+                                    while (word.Length > 0)
+                                    {
+                                        string nextWord = PopWord(ref forwarder);
+
+                                        if (nextWord.StartsWith('('))
+                                        {
+                                            word += " " + nextWord;
+                                            nextWord = PopWord(ref forwarder);
+                                        }
+
+                                        forwarderRecords.Add(GetForwarderRecord(NameServerAddress.Parse(word), _dnssecValidation, _configProxyServer));
+
+                                        word = nextWord;
+                                    }
+
+                                    if (forwarderRecords.Count == 0)
+                                        throw new FormatException("Invalid AdGuard Upstreams config file format: missing upstream servers.");
+
+                                    forwardings.Add(new Forwarding(forwarderRecords, domains));
                                 }
                             }
                             else
@@ -689,6 +712,30 @@ namespace AdvancedForwarding
                 }
             }
 
+            private static string PopWord(ref string line)
+            {
+                if (line.Length == 0)
+                    return line;
+
+                line = line.TrimStart(_popWordSeperator);
+
+                int i = line.IndexOfAny(_popWordSeperator);
+                string word;
+
+                if (i < 0)
+                {
+                    word = line;
+                    line = "";
+                }
+                else
+                {
+                    word = line.Substring(0, i);
+                    line = line.Substring(i + 1);
+                }
+
+                return word;
+            }
+
             #endregion
 
             #region public
diff --git a/Apps/AdvancedForwardingApp/adguard-upstreams.txt b/Apps/AdvancedForwardingApp/adguard-upstreams.txt
index 77674a51..a99f408f 100644
--- a/Apps/AdvancedForwardingApp/adguard-upstreams.txt
+++ b/Apps/AdvancedForwardingApp/adguard-upstreams.txt
@@ -4,7 +4,7 @@
 # Example:
 # 8.8.8.8
 # udp://9.9.9.9
-# [/host.com/example.com/]tls://1.1.1.1
+# [/host.com/example.com/]https://cloudflare-dns.com/dns-query (1.1.1.1) tls://1.1.1.1
 # [/maps.host.com/]#
 # [/home/]192.168.10.2
 # [/test.com/]https://dns.quad9.net/dns-query (9.9.9.9)