dest.go

package clusterf

import (
	"fmt"
	"github.com/qmsk/clusterf/config"
	"github.com/qmsk/clusterf/ipvs"
	"net"
	"syscall"
)

type Dest struct {
	ipvs.Dest
}

func configServiceBackend(ipvsService ipvs.Service, backend config.ServiceBackend, routes Routes, options IPVSOptions) (*ipvs.Dest, error) {
	ipvsDest := ipvs.Dest{
		FwdMethod: options.FwdMethod, // default, overriden by route
		Weight:    uint32(backend.Weight),
	}

	switch ipvsService.Af {
	case syscall.AF_INET:
		if backend.IPv4 == "" {
			return nil, nil
		} else if ip := net.ParseIP(backend.IPv4); ip == nil {
			return nil, fmt.Errorf("Invalid IPv4: %v", backend.IPv4)
		} else if ip4 := ip.To4(); ip4 == nil {
			return nil, fmt.Errorf("Invalid IPv4: %v", ip)
		} else {
			ipvsDest.Addr = ip4
		}
	case syscall.AF_INET6:
		if backend.IPv6 == "" {
			return nil, nil
		} else if ip := net.ParseIP(backend.IPv6); ip == nil {
			return nil, fmt.Errorf("Invalid IPv6: %v", backend.IPv6)
		} else if ip16 := ip.To16(); ip16 == nil {
			return nil, fmt.Errorf("Invalid IPv6: %v", ip)
		} else {
			ipvsDest.Addr = ip16
		}
	default:
		panic("invalid af")
	}

	switch ipvsService.Protocol {
	case syscall.IPPROTO_TCP:
		if backend.TCP == 0 {
			return nil, nil
		} else {
			ipvsDest.Port = backend.TCP
		}
	case syscall.IPPROTO_UDP:
		if backend.UDP == 0 {
			return nil, nil
		} else {
			ipvsDest.Port = backend.UDP
		}
	default:
		panic("invalid proto")
	}

	// apply routes
	route := routes.Lookup(ipvsDest.Addr)
	if route == nil {
		// as-is
		return &ipvsDest, nil
	} else if route.IPVSMethod == nil {
		// ignore
		return nil, nil
	} else {
		ipvsDest.FwdMethod = *route.IPVSMethod
	}

	// IPVS chaning to next frontend
	if route.Gateway != nil {
		// TODO: mixed-family routes
		ipvsDest.Addr = route.Gateway
		ipvsDest.Port = ipvsService.Port
	}

	return &ipvsDest, nil
}