allowances/db.go

package allowances

import (
	"encoding/json"
	"io/ioutil"
	"log"
	"os"
	"sync"

	"golang.org/x/crypto/bcrypt"
)

func GetHashes(filename string) (Passes, bool, error) {
	r := []string{}
	exists := false
	if !Exists(filename) {
		return r, exists, nil
	}
	exists = true
	f, err := os.Open(filename)
	if err != nil {
		return nil, exists, err
	}
	err = json.NewDecoder(f).Decode(&r)
	if err != nil {
		return nil, exists, err
	}
	return r, exists, nil
}

func AddPassword(filename, pw string) error {
	curPasses, _, err := GetHashes(filename)
	if err != nil {
		return err
	}
	hpass, err := bcrypt.GenerateFromPassword(
		[]byte(pw), bcrypt.DefaultCost)
	curPasses = append(curPasses, string(hpass))

	f, err := os.Create(filename)
	if err != nil {
		return err
	}
	if err := json.NewEncoder(f).Encode(curPasses); err != nil {
		return err
	}
	return nil
}

type Passes []string

func (p Passes) Check(attempt string) (bool, error) {
	// TODO: parallelize
	for _, hash := range p {
		err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(attempt))
		if err == nil {
			return true, err
		}
	}
	return false, nil
}

var dbMutex = sync.RWMutex{}

func loadChildren(filename string) (children map[string]int) {
	dbMutex.RLock()
	defer dbMutex.RUnlock()
	b, err := ioutil.ReadFile(filename)
	if err != nil {
		log.Fatal(err)
	}
	err = json.Unmarshal(b, &children)
	if err != nil {
		log.Fatal(err)
	}
	return
}

func dumpChildren(filename string, children map[string]int) {
	dbMutex.Lock()
	defer dbMutex.Unlock()
	b, err := json.Marshal(children)
	err = ioutil.WriteFile(filename, b, 0644)
	if err != nil {
		log.Fatal("serious issue writing children db file", err)
	}
	return
}