Add NewVisitorConn operation to server plugin system

[jareddarkweb]

Feature

Support NewVisitorConn operation in server plugin callbacks to enable pre-connection logic for STCP/SUDP proxies.

Motivation

Fixes #5273

When using stcp proxies, users may need to trigger pre-connection actions (e.g., Wake-on-LAN) before a visitor connects. Currently, there's no plugin hook for visitor connections.

Changes

• Add OpNewVisitorConn constant to plugin operations
• Create NewVisitorConnContent struct for plugin payloads
• Implement plugin manager handler for NewVisitorConn
• Integrate plugin callback in RegisterVisitorConn method
• Add comprehensive e2e tests
• Update documentation

Testing

• Code compiles without errors
• Existing tests pass
• New e2e tests added

Example Usage

[[httpPlugins]]
name = "wol-manager"
addr = "127.0.0.1:9001"
path = "/handler"
ops = ["NewVisitorConn"]

The plugin will receive notifications when a visitor attempts to connect to an stcp proxy, allowing pre-connection logic like Wake-on-LAN.

Make sure:

• Base: fatedier/frp / dev branch
• Compare: jareddarkweb/frp / feature/newvisitorconn-plugin branch

[kilo-code-bot]

WARNING: ProxyType is hard-coded to "stcp", so sudp visitor connections will be reported to plugins as the wrong protocol. Any plugin that branches on proxy_type will mis-handle or reject every sudp connection even though this hook is documented for both visitor-based proxy types.

[kilo-code-bot]

Code Review Summary

Status: 1 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
server/service.go	706	ProxyType is hard-coded to stcp, so plugins cannot distinguish sudp visitor connections correctly.

Other Observations (not in diff)

No additional issues found outside the diff.

Files Reviewed (6 files)

• doc/server_plugin.md - 0 issues
• pkg/plugin/server/manager.go - 0 issues
• pkg/plugin/server/plugin.go - 0 issues
• pkg/plugin/server/types.go - 0 issues
• server/service.go - 1 issue
• test/e2e/v1/plugin/server.go - 0 issues

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_{Reviewed by gpt-5.4-20260305 · 227,761 tokens}