proxy's Introduction

Proxy

HTTP/HTTPS proxy library with custom dialer, which receives in the context key proxy.ReqParamsK a *proxy.ReqParams instance with the IP that made the request, it's URL and method. It can be served using standard library server or fasthttp server, and has two builtin dialers for dialing with a specific network interface or parent proxy.

Install example server

With Go 1.13 or superior:

git clone [email protected]:lamg/proxy.git
cd proxy/cmd/proxy && go install

Example

This is a proxy that denies all the connections coming from IP addresses different from 127.0.0.1.

package main

import (
	"crypto/tls"
	"fmt"
	"net"
	h "net/http"
	"time"

	alg "github.com/lamg/algorithms"
	"github.com/lamg/proxy"
)

func main() {
	// localhost clients only
	ar, e := newAllowedRanges("127.0.0.1/32")
	if e == nil {
		p := proxy.NewProxy(ar.DialContext)
		server := &h.Server{
			Addr:         ":8080",
			Handler:      p,
			ReadTimeout:  5 * time.Second,
			WriteTimeout: 10 * time.Second,
			// Disable HTTP/2.
			TLSNextProto: make(map[string]func(*h.Server,
				*tls.Conn, h.Handler)),
		}
		e = server.ListenAndServe()
	}
	if e != nil {
		log.Fatal(e)
	}
}

type allowedRanges struct {
	ranges      []*net.IPNet
	timeout     time.Duration
}

func newAllowedRanges(cidrs ...string) (a *allowedRanges, e error) {
	a = &allowedRanges{
		ranges:      make([]*net.IPNet, len(cidrs)),
		timeout:     90 * time.Second,
	}
	ib := func(i int) (b bool) {
		_, a.ranges[i], e = net.ParseCIDR(cidrs[i])
		b = e != nil
		return
	}
	alg.BLnSrch(ib, len(cidrs))
	return
}

func (r *allowedRanges) DialContext(ctx context.Context, network,
	addr string) (c net.Conn, e error) {
	rqp := ctx.Value(proxy.ReqParamsK).(*proxy.ReqParams)
	ip := net.ParseIP(rqp.IP)
	ok, _ := alg.BLnSrch(
		func(i int) bool { return r.ranges[i].Contains(ip) },
		len(r.ranges),
	)
	if !ok {
		e = fmt.Errorf("Client IP '%s' out of range", rqp.IP)
	}
	if e == nil {
		ifd := &proxy.IfaceDialer{Timeout: r.timeout}
		c, e = ifd.Dial(network, addr)
	}
	return
}

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