Use dual-mode sockets for hostname endpoints to support IPv6-only brokers

[Copilot]

Hostname-based broker connections were always created with an IPv4 socket when DnsEndPoint.AddressFamily was Unspecified, which breaks AAAA-only environments. This change moves socket selection into a testable helper and uses a dual-mode IPv6 socket for the hostname/default path while preserving explicit-family and Unix behavior.

• Connection behavior

  • Added SocketFactory.createSocket in ConnectionPool.fs (internal, unit-testable).
  • Unspecified endpoints now create Socket(AddressFamily.InterNetworkV6, Stream, Tcp) with DualMode <- true.
  • Explicit InterNetwork, InterNetworkV6, and Unix handling remains unchanged from prior semantics.

• ConnectionPool integration

  • getSocket now delegates socket creation to SocketFactory.createSocket.
  • Existing connection flow, retry path, TLS/SNI setup, and certificate validation logic are unchanged.

• Unit coverage

  • Added tests/UnitTests/Internal/ConnectionPoolTests.fs.
  • New tests assert:
    • DnsEndPoint(host, port) => IPv6 + dual-mode + TCP stream socket.
    • Explicit IPv4 endpoint => IPv4 + TCP.
    • Explicit IPv6 endpoint => IPv6 + TCP.
  • Wired new test file into tests/UnitTests/UnitTests.fsproj.

module internal SocketFactory =
    let createSocket (endpoint: DnsEndPoint) : Socket =
        match endpoint.AddressFamily with
        | AddressFamily.Unspecified ->
            let socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp)
            socket.DualMode <- true
            socket
        | AddressFamily.Unix ->
            new Socket(AddressFamily.Unix, SocketType.Stream, ProtocolType.Unspecified)
        | family ->
            new Socket(family, SocketType.Stream, ProtocolType.Tcp)

[Copilot]

Pull request overview

This PR updates ConnectionPool socket creation for hostname-based DnsEndPoints so that AddressFamily.Unspecified uses an IPv6 dual-mode socket, enabling connections to IPv6-only (AAAA-only) brokers while keeping explicit address-family behavior testable via a dedicated helper.

Changes:

• Added internal SocketFactory.createSocket helper and refactored ConnectionPool.getSocket to use it.
• Changed AddressFamily.Unspecified socket creation to InterNetworkV6 with DualMode <- true.
• Added unit tests covering socket family selection for unspecified/IPv4/IPv6 endpoints and wired them into the UnitTests project.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/Pulsar.Client/Internal/ConnectionPool.fs	Introduces SocketFactory.createSocket and delegates socket creation from getSocket.
tests/UnitTests/Internal/ConnectionPoolTests.fs	Adds unit tests for socket family/protocol behavior of SocketFactory.
tests/UnitTests/UnitTests.fsproj	Includes the new ConnectionPoolTests.fs in the test project compilation list.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.