Add initial code

src/util.go

@@ -0,0 +1,161 @@
+package main
+
+import (
+	"crypto/sha1"
+	_ "embed"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/valyala/fasthttp"
+)
+
+var (
+	//go:embed default-icon.png
+	defaultIconBytes []byte
+	ipAddressRegExp  = regexp.MustCompile("^\\d{1,3}(\\.\\d{1,3}){3}$")
+)
+
+var (
+	ErrNoAddressMatch = errors.New("address does not match any known format")
+)
+
+func GetBlockedServerList() error {
+	resp, err := http.Get("https://sessionserver.mojang.com/blockedservers")
+
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+
+	if err != nil {
+		return err
+	}
+
+	blockedServersMutex.Lock()
+	blockedServers = strings.Split(string(body), "\n")
+	blockedServersMutex.Unlock()
+
+	return nil
+}
+
+func IsBlockedAddress(address string) bool {
+	split := strings.Split(strings.ToLower(address), ".")
+
+	isIPAddress := ipAddressRegExp.MatchString(address)
+
+	for k := range split {
+		newAddress := ""
+
+		switch k {
+		case 0:
+			{
+				newAddress = strings.Join(split, ".")
+
+				break
+			}
+		default:
+			{
+				if isIPAddress {
+					newAddress = fmt.Sprintf("%s.*", strings.Join(split[0:len(split)-k], "."))
+				} else {
+					newAddress = fmt.Sprintf("*.%s", strings.Join(split[k:], "."))
+				}
+
+				break
+			}
+		}
+
+		newAddressBytes := sha1.Sum([]byte(newAddress))
+		newAddressHash := hex.EncodeToString(newAddressBytes[:])
+
+		blockedServersMutex.Lock()
+
+		if Contains(blockedServers, newAddressHash) {
+			blockedServersMutex.Unlock()
+
+			return true
+		}
+
+		blockedServersMutex.Unlock()
+	}
+
+	return false
+}
+
+func ParseAddress(address string, defaultPort uint16) (string, uint16, error) {
+	result := strings.SplitN(address, ":", 2)
+
+	if len(result) < 1 {
+		return "", 0, ErrNoAddressMatch
+	}
+
+	if len(result) < 2 {
+		return result[0], defaultPort, nil
+	}
+
+	port, err := strconv.ParseUint(result[1], 10, 16)
+
+	if err != nil {
+		return "", 0, err
+	}
+
+	return result[0], uint16(port), nil
+}
+
+func WriteError(ctx *fasthttp.RequestCtx, err error, statusCode int, body ...string) {
+	ctx.SetStatusCode(statusCode)
+
+	if len(body) > 0 {
+		ctx.SetBodyString(body[0])
+	} else {
+		ctx.SetBodyString(http.StatusText(statusCode))
+	}
+
+	if err != nil {
+		log.Println(err)
+	}
+}
+
+func IsCacheEnabled(ctx *fasthttp.RequestCtx, cacheType, host string, port uint16) (bool, string, error) {
+	key := fmt.Sprintf("%s:%s-%d", cacheType, host, port)
+
+	if authKey := ctx.Request.Header.Peek("Authorization"); len(authKey) > 0 {
+		exists, err := r.Exists(fmt.Sprintf("auth_key:%s", authKey))
+
+		if err != nil {
+			WriteError(ctx, err, http.StatusInternalServerError)
+
+			return config.CacheEnable, key, err
+		}
+
+		if exists {
+			return false, key, nil
+		}
+	}
+
+	return config.CacheEnable, key, nil
+}
+
+func Contains[T comparable](arr []T, x T) bool {
+	for _, v := range arr {
+		if v == x {
+			return true
+		}
+	}
+
+	return false
+}