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|
package main
import (
"encoding/json"
"log"
"net"
)
const (
MESSAGE = "message"
AUTHENTICATE = "authenticate"
RENAME = "rename"
)
const (
SUCCESS = "success"
FAILURE = "failure"
)
type Message struct {
Type string
Data string
User string
}
type Response struct {
Status string
Data string
}
func parseMessage(data []byte) Message {
var m Message
// TODO(andrew): Добавить обработку ошибок
json.Unmarshal(data, &m)
return m
}
func toBytes(num uint32) []byte {
buf := make([]byte, 4)
var mask uint32 = 0x00FF
for i := 0; i < 4; i += 1 {
buf[4-i-1] = byte(num & mask)
num >>= 8
}
return buf
}
func fromBytes(data []byte) uint32 {
var num uint32
for i := 0; i < 4; i += 1 {
num += uint32(data[i] << ((4 - i - 1) * 8))
}
return num
}
func sendMessage(conn net.Conn, message []byte) error {
size := uint32(len(message))
_, err := conn.Write(toBytes(size))
if err != nil {
return err
}
_, err = conn.Write(message)
if err != nil {
return err
}
return nil
}
func handleConnection(conn net.Conn) {
defer conn.Close()
// 1 мегабайт
var maxBodySize uint32 = 1048576
maxAuthAttempts := 5
authAttempts := 0
authenticated := false
buf := make([]byte, 256)
for {
if authAttempts >= maxAuthAttempts {
resp, _ := json.Marshal(Response{
Status: FAILURE,
Data: "Превышено количество неавторизованных запросов",
})
_ = sendMessage(conn, resp)
break
}
_, err := conn.Read(buf)
if err != nil {
break
}
size := fromBytes(buf[:4])
if size > maxBodySize {
resp, _ := json.Marshal(Response{
Status: FAILURE,
Data: "Превышен максимальный размер запроса",
})
_ = sendMessage(conn, resp)
break
}
rawMessage := buf[4 : size+4]
message := parseMessage(rawMessage)
//fmt.Println(message.Data)
if message.Type == AUTHENTICATE {
// TODO(andrew): Добавить процесс аутентификации
if true {
authenticated = true
}
}
if !authenticated {
resp, _ := json.Marshal(Response{
Status: FAILURE,
Data: "Для работы с сервером необходима аутентификация",
})
err = sendMessage(conn, resp)
if err != nil {
break
}
authAttempts += 1
continue
}
if message.Data == "exit" {
break
}
resp, _ := json.Marshal(Response{
Status: SUCCESS,
Data: "some data",
})
err = sendMessage(conn, resp)
if err != nil {
break
}
}
}
func main() {
sock, err := net.Listen("tcp", "localhost:8080")
defer sock.Close()
handleError(err)
for {
conn, err := sock.Accept()
if err == nil {
go handleConnection(conn)
} else {
handleError(err)
}
}
}
func handleError(err error) {
if err != nil {
log.Fatal(err)
}
}
|
