config.go

package main

import (
	"encoding/json"

	xds "github.com/cncf/xds/go/xds/type/v3"
	"github.com/envoyproxy/envoy/contrib/golang/filters/http/source/go/pkg/api"
	"github.com/envoyproxy/envoy/contrib/golang/filters/http/source/go/pkg/http"
	"google.golang.org/protobuf/types/known/anypb"
)

func init() {
	http.RegisterHttpFilterConfigFactory("basic-auth", configFactory)
	http.RegisterHttpFilterConfigParser(&parser{})
}

type config struct {
	users map[string]string
}

type rawConfig struct {
	Users []User
}

type User struct {
	Username string
	Password string
}

type parser struct {
}

func (p *parser) Parse(any *anypb.Any) (interface{}, error) {
	configStruct := &xds.TypedStruct{}
	if err := any.UnmarshalTo(configStruct); err != nil {
		return nil, err
	}

	v := configStruct.Value
	conf := &config{}
	rc := &rawConfig{}

	data, err := v.MarshalJSON()
	if err != nil {
		return nil, err
	}

	err = json.Unmarshal(data, rc)
	if err != nil {
		return nil, err
	}

	conf.users = paresUser2Map(&rc.Users)

	return conf, nil
}

func paresUser2Map(users *[]User) map[string]string {
	userMap := make(map[string]string)
	for _, user := range *users {
		if user.Username == "" {
			continue
		}
		userMap[user.Username] = user.Password
	}
	return userMap
}

func (p *parser) Merge(parent interface{}, child interface{}) interface{} {
	parentConfig := parent.(*config)
	childConfig := child.(*config)

	newConfig := *parentConfig
	if childConfig.users != nil {
		mergeUserMap(newConfig.users, childConfig.users)
	}
	return &newConfig
}

func mergeUserMap(new, child map[string]string) {
	for username, password := range child {
		new[username] = password
	}
}

func configFactory(c interface{}) api.StreamFilterFactory {
	conf, ok := c.(*config)
	if !ok {
		panic("unexpected config type")
	}
	return func(callbacks api.FilterCallbackHandler) api.StreamFilter {
		return &filter{
			callbacks: callbacks,
			config:    conf,
		}
	}
}