added new basic auth endpoint

pkg/server/auth.go

@@ -0,0 +1,119 @@
+// Copyright (C) 2022 Marius Schellenberger
+
+package server
+
+import (
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"io"
+	weakrand "math/rand"
+	"sync"
+	"time"
+
+	"git.giftfish.de/ston1th/goacc/pkg/db"
+)
+
+type AuthValidator interface {
+	Login(username, password string) (auth bool)
+}
+
+const cacheSize = 100
+
+func init() {
+	weakrand.Seed(time.Now().UnixNano())
+}
+
+type DBLoginValidator struct {
+	db *db.DB
+}
+
+func NewDBLoginValidator(db *db.DB) *DBLoginValidator {
+	return &DBLoginValidator{db}
+}
+
+func (val *DBLoginValidator) Login(username, password string) bool {
+	_, err := val.db.Login(username, password)
+	return err == nil
+}
+
+type cache struct {
+	mu sync.RWMutex
+	m  map[string]bool
+}
+
+func newCache() *cache {
+	return &cache{m: make(map[string]bool)}
+}
+
+func (c *cache) get(k string) (v, ok bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	v, ok = c.m[k]
+	return
+}
+
+func (c *cache) set(k string, v bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.makeRoom()
+	c.m[k] = v
+}
+
+func (c *cache) makeRoom() {
+	n := len(c.m)
+	if n < cacheSize {
+		return
+	}
+	del := n / 10
+	if del < 1 {
+		del = 1
+	}
+	for i := 0; i <= del; i++ {
+		rnd := weakrand.Intn(len(c.m))
+		j := 0
+		for k := range c.m {
+			if j == rnd {
+				delete(c.m, k)
+				break
+			}
+			j++
+		}
+	}
+}
+
+type BasicAuth struct {
+	mu    sync.Mutex
+	auth  AuthValidator
+	cache *cache
+	key   []byte
+}
+
+func NewBasicAuth(auth AuthValidator) (*BasicAuth, error) {
+	key := make([]byte, 32)
+	_, err := io.ReadFull(rand.Reader, key)
+	return &BasicAuth{
+		auth:  auth,
+		cache: newCache(),
+		key:   key,
+	}, err
+}
+
+func (a *BasicAuth) genkey(username, password string) string {
+	h := hmac.New(sha256.New, a.key)
+	h.Write(append([]byte(username), []byte(password)...))
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+func (a *BasicAuth) Auth(username, password string) (auth bool) {
+	k := a.genkey(username, password)
+	auth, ok := a.cache.get(k)
+	if !ok {
+		a.mu.Lock()
+		auth = a.auth.Login(username, password)
+		a.mu.Unlock()
+		a.cache.set(k, auth)
+	}
+	return
+}