SPOE in Go

An implementation of the SPOP protocol in Go. (https://www.haproxy.org/download/2.0/doc/SPOE.txt)

SPOE

From Haproxy's documentation :

SPOE is a feature introduced in HAProxy 1.7. It makes possible the communication with external components to retrieve some info. The idea started with the problems caused by most ldap libs not working fine in event-driven systems (often at least the connect() is blocking). So, it is hard to properly implement Single Sign On solution (SSO) in HAProxy. The SPOE will ease this kind of processing, or we hope so.

Now, the aim of SPOE is to allow any kind of offloading on the streams. First releases, besides being experimental, won't do lot of things. As we will see, there are few handled events and even less actions supported. Actually, for now, the SPOE can offload the processing before "tcp-request content", "tcp-response content", "http-request" and "http-response" rules. And it only supports variables definition. But, in spite of these limited features, we can easily imagine to implement SSO solution, ip reputation or ip geolocation services.

How to use

package main

import (
	"fmt"
	"net"

	"log"

	spoe "github.com/TheLunarCompany/haproxy-spoe-go"
)

func getReputation(ip net.IP) (float64, error) {
	// implement IP reputation code here
	return 1.0, nil
}

func main() {
	agent := spoe.New(func(messages *spoe.MessageIterator) ([]spoe.Action, error) {
		reputation := 0.0

		for messages.Next() {
			msg := messages.Message

			if msg.Name != "ip-rep" {
				continue
			}

			var ip net.IP
			for msg.Args.Next() {
				arg := msg.Args.Arg

				if arg.Name == "ip" {
					var ok bool
					ip, ok = arg.Value.(net.IP)
					if !ok {
						return nil, fmt.Errorf("spoe handler: expected ip in message, got %+v", ip)
					}
				}
			}

			var err error
			reputation, err = getReputation(ip)
			if err != nil {
				return nil, fmt.Errorf("spoe handler: error processing request: %s", err)
			}
		}

		return []spoe.Action{
			spoe.ActionSetVar{
				Name:  "reputation",
				Scope: spoe.VarScopeSession,
				Value: reputation,
			},
		}, nil
	})

	if err := agent.ListenAndServe(":9000"); err != nil {
		log.Fatal(err)
	}
}