Refactor(dialer): with socket options

[xjasonlyu]

No description provided.

[Copilot]

Pull request overview

Refactors the dialing layer from a mutable DefaultDialer with atomic fields into a socket-option registration model, and updates engine/DNS integration to use the new dialer entrypoints.

Changes:

• Replace DefaultDialer’s per-field configuration (interface/mark) with a SocketOption interface and registration API.
• Implement WithBindToInterface / WithRoutingMark per-OS using syscall.RawConn control hooks.
• Update engine and DNS resolver to use dialer.RegisterSockOpt(...) and dialer.DialContext.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
engine/engine.go	Switches interface binding + fwmark configuration to socket-option registration.
dns/resolver.go	Points the Go DNS resolver dialer at the new dialer.DialContext wrapper.
dialer/dialer.go	Introduces option registration, storage, and application via net.Dialer / net.ListenConfig control hooks.
dialer/sockopt.go	Adds SocketOption/SocketOptionFunc, an unsupported sentinel, and a shared RawConn.Control helper.
dialer/sockopt_linux.go	Adds Linux implementations for bind-to-device and SO_MARK via socket options.
dialer/sockopt_darwin.go	Adds Darwin bind-to-interface socket option; routing mark is unsupported.
dialer/sockopt_windows.go	Adds Windows bind-to-interface socket option; routing mark is unsupported.
dialer/sockopt_freebsd.go	Keeps routing-mark behavior via socket option; bind-to-interface is unsupported.
dialer/sockopt_openbsd.go	Keeps routing-mark behavior via socket option; bind-to-interface is unsupported.
dialer/sockopt_others.go	Removes the previous non-unix/non-windows no-op implementation.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

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