[WIP]TCP transport support ipv6 #1067

LCAIZJ · 2025-11-17T10:32:23Z

Description

vllm-project/vllm-ascend#4103 use tcp transport with error E20251112 17:02:55.861567 33158 tcp_transport.cpp:480] TcpTransport::startTransfer encountered an ASIO exception. Slice details - source_addr: 0x12d11ac40000, length: 32768, opcode: 0, target_id: 1. Exception: resolve: Host not found (authoritative)

Signed-off-by: LCAIZJ <[email protected]>

gemini-code-assist · 2025-11-17T10:32:42Z

Summary of Changes

Hello @LCAIZJ, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a host resolution error encountered with TCP transport by introducing comprehensive IPv6 support. The changes modify the TCP transport layer to correctly handle both IPv4 and IPv6 addresses for listening and connecting, enhancing network compatibility and resolving issues related to host not found errors in modern network environments.

Highlights

IPv6 Support for TCP Acceptor: The TCP acceptor in TcpContext has been reconfigured to use an IPv6 endpoint, while also explicitly setting v6_only(false) to allow it to accept both IPv4 and IPv6 connections.
Dynamic IP Version Resolution: The resolver.resolve call in TcpTransport::startTransfer no longer explicitly specifies asio::ip::tcp::v4(), enabling the resolver to dynamically determine the appropriate IP version (IPv4 or IPv6) for outgoing connections based on the provided hostname.

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Code Review

This pull request adds IPv6 support to the TCP transport layer. The changes correctly modify the server-side acceptor to create a dual-stack (IPv4/IPv6) socket and update the client-side resolver to handle both IPv4 and IPv6 addresses. My review includes a suggestion to improve error handling and robustness in the acceptor setup logic.

gemini-code-assist · 2025-11-17T10:33:54Z

mooncake-transfer-engine/src/transport/tcp_transport/tcp_transport.cpp

+    TcpContext(short port) : acceptor(io_context) {
+        asio::ip::tcp::endpoint endpoint(asio::ip::tcp::v6(), port);
+
+        acceptor.open(endpoint.protocol());
+        acceptor.set_option(asio::ip::v6_only(false));
+        acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));
+        acceptor.bind(endpoint);
+        acceptor.listen();
+    }


The operations on the asio::ip::tcp::acceptor (open, set_option, bind, listen) can throw asio::system_error on failure (e.g., if the port is already in use). Since this is in a constructor, an unhandled exception will prevent the object from being fully constructed and will likely crash the application. It's better to wrap these operations in a try-catch block to log the specific error before re-throwing it, which improves debuggability. Additionally, it's good practice to specify a backlog size for listen.

TcpContext(short port) : acceptor(io_context) { try { asio::ip::tcp::endpoint endpoint(asio::ip::tcp::v6(), port); acceptor.open(endpoint.protocol()); acceptor.set_option(asio::ip::v6_only(false)); acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true)); acceptor.bind(endpoint); acceptor.listen(asio::socket_base::max_listen_connections); } catch (const asio::system_error& e) { LOG(ERROR) << "Failed to setup TCP acceptor: " << e.what(); throw; } }

stmatengss · 2025-11-18T10:47:13Z

/home/runner/work/Mooncake/Mooncake/mooncake-transfer-engine/src/transport/tcp_transport/tcp_transport.cpp:263:39: error: ‘v6_only’ is not a member of ‘asio::ip’
  263 |         acceptor.set_option(asio::ip::v6_only(false));

@LCAIZJ Could you resolve this compiling issue?

Copilot

Pull Request Overview

This PR adds IPv6 support to the TCP transport layer to resolve connection issues when using IPv6 addresses. The changes enable the TCP transport to accept both IPv4 and IPv6 connections using dual-stack sockets.

Modified the TcpContext constructor to use IPv6 endpoints with dual-stack support (v6_only=false)
Updated the resolver to automatically determine the protocol (IPv4 or IPv6) based on the provided hostname/IP address

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Copilot · 2025-11-19T08:40:00Z

mooncake-transfer-engine/src/transport/tcp_transport/tcp_transport.cpp

+        asio::ip::tcp::endpoint endpoint(asio::ip::tcp::v6(), port);
+
+        acceptor.open(endpoint.protocol());
+        acceptor.set_option(asio::ip::v6_only(false));
+        acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));
+        acceptor.bind(endpoint);
+        acceptor.listen();


[nitpick] Setting v6_only(false) enables dual-stack mode, allowing the IPv6 socket to accept both IPv4 and IPv6 connections. However, on some systems (particularly older Linux kernels or Windows systems), this option might not be supported or may have different default behaviors. Consider documenting this requirement or adding a fallback mechanism to create an IPv4-only acceptor if IPv6 with dual-stack fails.

Suggested change

asio::ip::tcp::endpoint endpoint(asio::ip::tcp::v6(), port);

acceptor.open(endpoint.protocol());

acceptor.set_option(asio::ip::v6_only(false));

acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));

acceptor.bind(endpoint);

acceptor.listen();

asio::ip::tcp::endpoint endpoint_v6(asio::ip::tcp::v6(), port);

asio::ip::tcp::endpoint endpoint_v4(asio::ip::tcp::v4(), port);

bool dual_stack_ok = true;

try {

acceptor.open(endpoint_v6.protocol());

acceptor.set_option(asio::ip::v6_only(false));

acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));

acceptor.bind(endpoint_v6);

acceptor.listen();

} catch (const std::exception& e) {

LOG(WARNING) << "Dual-stack (IPv6+IPv4) socket setup failed: " << e.what()

<< ". Falling back to IPv4-only acceptor.";

dual_stack_ok = false;

}

if (!dual_stack_ok) {

acceptor.close();

acceptor.open(endpoint_v4.protocol());

acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));

acceptor.bind(endpoint_v4);

acceptor.listen();

}

tcp transport support ipv6

19fbcc9

Signed-off-by: LCAIZJ <[email protected]>

gemini-code-assist bot reviewed Nov 17, 2025

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stmatengss mentioned this pull request Nov 17, 2025

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Copilot finished reviewing on behalf of stmatengss November 19, 2025 08:39

Copilot AI reviewed Nov 19, 2025

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[WIP]TCP transport support ipv6 #1067

[WIP]TCP transport support ipv6 #1067

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-        asio::ip::tcp::endpoint endpoint(asio::ip::tcp::v6(), port);
-        acceptor.open(endpoint.protocol());
-        acceptor.set_option(asio::ip::v6_only(false));
-        acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));
-        acceptor.bind(endpoint);
-        acceptor.listen();
+        asio::ip::tcp::endpoint endpoint_v6(asio::ip::tcp::v6(), port);
+        asio::ip::tcp::endpoint endpoint_v4(asio::ip::tcp::v4(), port);
+        bool dual_stack_ok = true;
+        try {
+            acceptor.open(endpoint_v6.protocol());
+            acceptor.set_option(asio::ip::v6_only(false));
+            acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));
+            acceptor.bind(endpoint_v6);
+            acceptor.listen();
+        } catch (const std::exception& e) {
+            LOG(WARNING) << "Dual-stack (IPv6+IPv4) socket setup failed: " << e.what()
+                         << ". Falling back to IPv4-only acceptor.";
+            dual_stack_ok = false;
+        }
+        if (!dual_stack_ok) {
+            acceptor.close();
+            acceptor.open(endpoint_v4.protocol());
+            acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));
+            acceptor.bind(endpoint_v4);
+            acceptor.listen();
+        }

[WIP]TCP transport support ipv6 #1067

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LCAIZJ commented Nov 17, 2025

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