fix: use dual-stack binding and proper error handling for IPv6 sockets#151
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englishm-cloudflare wants to merge 1 commit intocloudflare:mainfrom
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fix: use dual-stack binding and proper error handling for IPv6 sockets#151englishm-cloudflare wants to merge 1 commit intocloudflare:mainfrom
englishm-cloudflare wants to merge 1 commit intocloudflare:mainfrom
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Replace the default [::]:0 bind behavior with socket2-based binding that explicitly sets IPV6_V6ONLY=false for cross-platform dual-stack support. On macOS/Windows, IPv6 sockets are IPv6-only by default, causing connection failures when targeting IPv4-only hosts. Changes: - Add bind_smart() using socket2 to request dual-stack on IPv6 sockets - Config::new() now returns Result instead of panicking on bind failure - Args::load() falls back to 0.0.0.0:port with a warning if IPv6 fails - Track actual dual-stack state at bind time instead of using compile-time cfg!(target_os = "linux") assumption - Thread is_dual_stack through Config -> Endpoint -> Client for accurate address_family() detection at connect time
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Summary
[::]:0bind withsocket2-based binding that explicitly setsIPV6_V6ONLY=false, enabling cross-platform dual-stack (IPv4 + IPv6) support on a single socket.Config::new()now returnsResultinstead of panicking on bind failure.Args::load()falls back to0.0.0.0:portwith a warning if IPv6 binding fails.cfg!(target_os = "linux")assumption) and threadis_dual_stackthroughConfig→Endpoint→Clientsoaddress_family()detection is accurate at connect time.Motivation
On macOS and Windows, IPv6 sockets default to
IPV6_V6ONLY=true, which means binding to[::]only accepts IPv6 connections. When a client on one of these platforms tries to connect to an IPv4-only host, the connection silently fails. Linux happens to default to dual-stack, so this went unnoticed there.This change makes the behavior consistent across platforms by explicitly requesting dual-stack mode, with a graceful fallback to IPv4-only when the OS or network doesn't support it.