From aec9f60290aaeab8ccabf3aaf287e5534d4869b4 Mon Sep 17 00:00:00 2001
From: Christien Rioux <chris@veilid.org>
Date: Thu, 13 Jul 2023 23:22:37 -0400
Subject: [PATCH] ipv6 nat

---
 .../native/network_class_discovery.rs         | 71 ++++++++++++-------
 .../src/network_manager/types/address.rs      |  4 +-
 2 files changed, 49 insertions(+), 26 deletions(-)

diff --git a/veilid-core/src/network_manager/native/network_class_discovery.rs b/veilid-core/src/network_manager/native/network_class_discovery.rs
index 3de494e1..3ddccde1 100644
--- a/veilid-core/src/network_manager/native/network_class_discovery.rs
+++ b/veilid-core/src/network_manager/native/network_class_discovery.rs
@@ -622,37 +622,58 @@ impl Network {
         context: &DiscoveryContext,
         protocol_type: ProtocolType,
     ) -> EyreResult<()> {
+        let mut retry_count = {
+            let c = self.config.get();
+            c.network.restricted_nat_retries
+        };
+
         // Start doing ipv6 protocol
         context.protocol_begin(protocol_type, AddressType::IPV6);
 
-        log_net!(debug "=== update_ipv6_protocol_dialinfo {:?} ===", protocol_type);
-
-        // Get our external address from some fast node, call it node 1
-        if !context.protocol_get_external_address_1().await {
-            // If we couldn't get an external address, then we should just try the whole network class detection again later
-            return Ok(());
-        }
-
-        // If our local interface list doesn't contain external_1 then there is an Ipv6 NAT in place
-        {
-            let inner = context.inner.lock();
-            if !inner
-                .intf_addrs
-                .as_ref()
-                .unwrap()
-                .contains(inner.external_1_address.as_ref().unwrap())
-            {
-                // IPv6 NAT is not supported today
-                log_net!(warn
-                    "IPv6 NAT is not supported for external address: {}",
-                    inner.external_1_address.unwrap()
-                );
+        // Loop for restricted NAT retries
+        loop {
+            log_net!(debug
+                "=== update_ipv6_protocol_dialinfo {:?} tries_left={} ===",
+                protocol_type,
+                retry_count
+            );
+            // Get our external address from some fast node, call it node 1
+            if !context.protocol_get_external_address_1().await {
+                // If we couldn't get an external address, then we should just try the whole network class detection again later
                 return Ok(());
             }
-        }
 
-        // No NAT
-        context.protocol_process_no_nat().await?;
+            // If our local interface list contains external_1 then there is no NAT in place
+            {
+                let res = {
+                    let inner = context.inner.lock();
+                    inner
+                        .intf_addrs
+                        .as_ref()
+                        .unwrap()
+                        .contains(inner.external_1_address.as_ref().unwrap())
+                };
+                if res {
+                    // No NAT
+                    context.protocol_process_no_nat().await?;
+
+                    // No more retries
+                    break;
+                }
+            }
+
+            // There is -some NAT-
+            if context.protocol_process_nat().await? {
+                // We either got dial info or a network class without one
+                break;
+            }
+
+            // If we tried everything, break anyway after N attempts
+            if retry_count == 0 {
+                break;
+            }
+            retry_count -= 1;
+        }
 
         Ok(())
     }
diff --git a/veilid-core/src/network_manager/types/address.rs b/veilid-core/src/network_manager/types/address.rs
index 45ec1c98..0dbb0e95 100644
--- a/veilid-core/src/network_manager/types/address.rs
+++ b/veilid-core/src/network_manager/types/address.rs
@@ -1,5 +1,7 @@
 use super::*;
 
+// Ordering here matters, IPV6 is preferred to IPV4 in dial info sorts
+// See issue #236 for eventual resolution of this unfortunate implementation
 #[derive(
     Copy,
     Clone,
@@ -17,8 +19,8 @@ use super::*;
 )]
 #[archive_attr(repr(u8), derive(CheckBytes))]
 pub enum Address {
-    IPV4(Ipv4Addr),
     IPV6(Ipv6Addr),
+    IPV4(Ipv4Addr),
 }
 
 impl Default for Address {