From f7a9ecafd3aa6a63ff838c7ce01f8451afd2b46d Mon Sep 17 00:00:00 2001
From: Jonathan Cobb <jonathan@kyuss.org>
Date: Sat, 19 Sep 2020 12:03:49 -0400
Subject: [PATCH] try tcp first for dns resolution on windows

---
 src/dns_cache.rs | 72 ++++++++++++++++++++++++++++++++++--------------
 src/net.rs       |  2 +-
 2 files changed, 53 insertions(+), 21 deletions(-)

diff --git a/src/dns_cache.rs b/src/dns_cache.rs
index fcd09f5..8aaa31d 100644
--- a/src/dns_cache.rs
+++ b/src/dns_cache.rs
@@ -25,29 +25,61 @@ use tokio::task::JoinHandle;
 use trust_dns_resolver::TokioAsyncResolver;
 use trust_dns_resolver::config::{NameServerConfig, Protocol, ResolverConfig, ResolverOpts};
 
+use whoami::{platform, Platform};
+
 pub async fn create_resolver(dns1_sock: SocketAddr, dns2_sock: SocketAddr) -> TokioAsyncResolver {
     let mut resolver_config: ResolverConfig = ResolverConfig::new();
 
-    resolver_config.add_name_server(NameServerConfig {
-        socket_addr: dns1_sock,
-        protocol: Protocol::Udp,
-        tls_dns_name: None
-    });
-    resolver_config.add_name_server(NameServerConfig {
-        socket_addr: dns1_sock,
-        protocol: Protocol::Tcp,
-        tls_dns_name: None
-    });
-    resolver_config.add_name_server(NameServerConfig {
-        socket_addr: dns2_sock,
-        protocol: Protocol::Udp,
-        tls_dns_name: None
-    });
-    resolver_config.add_name_server(NameServerConfig {
-        socket_addr: dns2_sock,
-        protocol: Protocol::Tcp,
-        tls_dns_name: None
-    });
+    let platform : Platform = platform();
+    match platform {
+        Platform::Windows => {
+            // try TCP first on Windows, UDP sockets may have permission issues (?)
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns1_sock,
+                protocol: Protocol::Tcp,
+                tls_dns_name: None
+            });
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns2_sock,
+                protocol: Protocol::Tcp,
+                tls_dns_name: None
+            });
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns1_sock,
+                protocol: Protocol::Udp,
+                tls_dns_name: None
+            });
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns2_sock,
+                protocol: Protocol::Udp,
+                tls_dns_name: None
+            });
+        }
+        _ => {
+            // try UDP first on all other platforms, usually faster
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns1_sock,
+                protocol: Protocol::Udp,
+                tls_dns_name: None
+            });
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns2_sock,
+                protocol: Protocol::Udp,
+                tls_dns_name: None
+            });
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns1_sock,
+                protocol: Protocol::Tcp,
+                tls_dns_name: None
+            });
+            resolver_config.add_name_server(NameServerConfig {
+                socket_addr: dns2_sock,
+                protocol: Protocol::Tcp,
+                tls_dns_name: None
+            });
+        }
+    };
+
     TokioAsyncResolver::tokio(resolver_config, ResolverOpts::default()).await.unwrap()
 }
 
diff --git a/src/net.rs b/src/net.rs
index a0c6244..d42ba30 100644
--- a/src/net.rs
+++ b/src/net.rs
@@ -46,7 +46,7 @@ pub fn is_private_ip(ip : &String) -> bool {
 }
 
 pub fn ip_gateway() -> String {
-    let platform: Platform = platform();
+    let platform : Platform = platform();
     let gateway = match platform {
         Platform::Windows => {
             let output = Command::new("C:\\Windows\\System32\\cmd.exe")