From 2a6152b83246f07333467ccc1c005d1ac73f9369 Mon Sep 17 00:00:00 2001
From: afjoseph <7126721+afjoseph@users.noreply.github.com>
Date: Thu, 28 Oct 2021 10:13:21 +0200
Subject: [PATCH] [trackerscraper] Add custom DNS lookup function

---
 config.go          | 3 +++
 torrent.go         | 5 +++--
 tracker_scraper.go | 9 ++++++++-
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/config.go b/config.go
index 3d370d55..50c46afa 100644
--- a/config.go
+++ b/config.go
@@ -90,6 +90,9 @@ type ClientConfig struct {
 	// Defines proxy for HTTP requests, such as for trackers. It's commonly set from the result of
 	// "net/http".ProxyURL(HTTPProxy).
 	HTTPProxy func(*http.Request) (*url.URL, error)
+	// Takes a tracker's hostname and requests DNS A and AAAA records.
+	// Used in case DNS lookups require a special setup (i.e., dns-over-https)
+	TrackerIpFetcher func(*url.URL) ([]net.IP, error)
 	// HTTPUserAgent changes default UserAgent for HTTP requests
 	HTTPUserAgent string
 	// Updated occasionally to when there's been some changes to client
diff --git a/torrent.go b/torrent.go
index 5f18df1f..8fa4c7de 100644
--- a/torrent.go
+++ b/torrent.go
@@ -1577,8 +1577,9 @@ func (t *Torrent) startScrapingTracker(_url string) {
 			}
 		}
 		newAnnouncer := &trackerScraper{
-			u: *u,
-			t: t,
+			u:         *u,
+			t:         t,
+			ipFetcher: t.cl.config.TrackerIpFetcher,
 		}
 		go newAnnouncer.Run()
 		return newAnnouncer
diff --git a/tracker_scraper.go b/tracker_scraper.go
index c339c2b4..f9d37d86 100644
--- a/tracker_scraper.go
+++ b/tracker_scraper.go
@@ -21,6 +21,7 @@ type trackerScraper struct {
 	u            url.URL
 	t            *Torrent
 	lastAnnounce trackerAnnounceResult
+	ipFetcher    func(*url.URL) ([]net.IP, error)
 }
 
 type torrentTrackerAnnouncer interface {
@@ -66,7 +67,13 @@ type trackerAnnounceResult struct {
 }
 
 func (me *trackerScraper) getIp() (ip net.IP, err error) {
-	ips, err := net.LookupIP(me.u.Hostname())
+	var ips []net.IP
+	if me.ipFetcher != nil {
+		ips, err = me.ipFetcher(&me.u)
+	} else {
+		// Do a regular dns lookup
+		ips, err = net.LookupIP(me.u.Hostname())
+	}
 	if err != nil {
 		return
 	}