isle/go/daemon/child_dnsmasq.go

package daemon

import (
	"context"
	"fmt"
	"isle/bootstrap"
	"isle/dnsmasq"
	"path/filepath"
	"sort"

	"code.betamike.com/micropelago/pmux/pmuxlib"
	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
)

func dnsmasqConfig(
	daemonConfig Config, hostBootstrap bootstrap.Bootstrap,
) dnsmasq.ConfData {
	hostsSlice := make([]dnsmasq.ConfDataHost, 0, len(hostBootstrap.Hosts))
	for _, host := range hostBootstrap.Hosts {
		hostsSlice = append(hostsSlice, dnsmasq.ConfDataHost{
			Name: string(host.Name),
			IP:   host.IP().String(),
		})
	}

	sort.Slice(hostsSlice, func(i, j int) bool {
		return hostsSlice[i].IP < hostsSlice[j].IP
	})

	return dnsmasq.ConfData{
		Resolvers: daemonConfig.DNS.Resolvers,
		Domain:    hostBootstrap.NetworkCreationParams.Domain,
		IP:        hostBootstrap.ThisHost().IP().String(),
		Hosts:     hostsSlice,
	}
}

func dnsmasqWriteConfig(
	runtimeDirPath string,
	daemonConfig Config,
	hostBootstrap bootstrap.Bootstrap,
) (
	string, error,
) {
	var (
		confPath = filepath.Join(runtimeDirPath, "dnsmasq.conf")
		confData = dnsmasqConfig(daemonConfig, hostBootstrap)
	)

	if err := dnsmasq.WriteConfFile(confPath, confData); err != nil {
		return "", fmt.Errorf("writing dnsmasq.conf to %q: %w", confPath, err)
	}

	return confPath, nil
}

func dnsmasqPmuxProcConfig(
	logger *mlog.Logger,
	runtimeDirPath, binDirPath string,
	daemonConfig Config,
	hostBootstrap bootstrap.Bootstrap,
) (
	pmuxlib.ProcessConfig, error,
) {
	confPath, err := dnsmasqWriteConfig(
		runtimeDirPath, daemonConfig, hostBootstrap,
	)
	if err != nil {
		return pmuxlib.ProcessConfig{}, fmt.Errorf(
			"writing dnsmasq config: %w", err,
		)
	}

	return pmuxlib.ProcessConfig{
		Cmd:  filepath.Join(binDirPath, "dnsmasq"),
		Args: []string{"-d", "-C", confPath},
		StartAfterFunc: func(ctx context.Context) error {
			// TODO consider a shared dnsmasq across all the daemon's networks.
			// This would have a few benefits:
			// - Less processes, less problems
			// - Less configuration for the user in the case of more than one
			//   network.
			// - Can listen on 127.0.0.x:53, rather than on the nebula address.
			//   This allows DNS to come up before nebula, which is helpful when
			//   nebula depends on DNS.
			return waitForNebula(ctx, logger, hostBootstrap)
		},
	}, nil
}