From 50bed1e67a4b12a14132ae649ca91019472573ce Mon Sep 17 00:00:00 2001
From: WofWca <wofwca@protonmail.com>
Date: Sat, 1 Mar 2025 23:44:03 +0400
Subject: [PATCH] refactor: docstring for checkIsRelayURLAcceptable

Related: https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40378.
---
 proxy/lib/snowflake.go | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/proxy/lib/snowflake.go b/proxy/lib/snowflake.go
index 18a321a..7bd9c15 100644
--- a/proxy/lib/snowflake.go
+++ b/proxy/lib/snowflake.go
@@ -688,7 +688,13 @@ func (sf *SnowflakeProxy) runSession(sid string) {
 	}
 }
 
-// Returns nil if the relayURL is acceptable
+// Returns nil if the relayURL is acceptable.
+// This is a pure function.
+// If the hostname in the `relayURL` is not an IP address
+// (but a name instead, e.g. `localhost`),
+// this function will _not_ perform a DNS request to figure out
+// if the name resolves to a private IP address,
+// i.e. the private / public check will effectively be skipped.
 func checkIsRelayURLAcceptable(
 	allowedHostNamePattern string,
 	allowPrivateIPs bool,