Glang 的http Proxy，请求转发

最近在做cmdb的agent-server，原本主机（700台左右）都是在内网环境，本以为网络这块没啥幺蛾子，但是还是出现了网络不通的情况；解决方式2种，1 从机房防火墙开通策略，2 通过已有的（zabbix已使用过）代理网络进行讯通。

最后:推荐使用 github.com/go-httpproxy/httpproxy 使用，易上手、好用、支持自定义拦截。

package main

import (
	"log"
	"net/http"
	"strings"

	"github.com/go-httpproxy/httpproxy"
)

func OnError(ctx *httpproxy.Context, where string,
	err *httpproxy.Error, opErr error) {
	// Log errors.
	log.Printf("ERR: %s: %s [%s]", where, err, opErr)
}

func OnAccept(ctx *httpproxy.Context, w http.ResponseWriter,
	r *http.Request) bool {
	// Handle local request has path "/info"
	if r.Method == "GET" && !r.URL.IsAbs() && r.URL.Path == "/info" {
		w.Write([]byte("This is go-httpproxy."))
		return true
	}
	if strings.Index(r.URL.String(), "xxx") == -1 {
		// 可以做一些拦截的事情
		return true
	}
	return false
}

func OnConnect(ctx *httpproxy.Context, host string) (
	ConnectAction httpproxy.ConnectAction, newHost string) {
	// Apply "Man in the Middle" to all ssl connections. Never change host.
	log.Printf("INFO: Proxy: %s----%s", host,ctx.ConnectHost)
	return httpproxy.ConnectMitm, host
}

func OnRequest(ctx *httpproxy.Context, req *http.Request) (
	resp *http.Response) {
	// Log proxying requests.
	log.Printf("INFO: Proxy: %s %s", req.Method, req.URL.String())
	return
}

func OnResponse(ctx *httpproxy.Context, req *http.Request,
	resp *http.Response) {
	// Add header "Via: go-httpproxy".
	resp.Header.Add("heliuyan", "heliuyan")
}

func main() {
	// Create a new proxy with default certificate pair.
	prx, _ := httpproxy.NewProxy()

	// Set handlers.
	prx.OnError = OnError
	prx.OnAccept = OnAccept
	prx.OnConnect = OnConnect
	prx.OnRequest = OnRequest
	prx.OnResponse = OnResponse

	// Listen...
	http.ListenAndServe(":12344", prx)
}