Golangによるsocket通信(1)

server.go

package main


import (
    "fmt"
    "net"
    "os"
    "time"

    "./utils"
    "./encryption"
    "math/big"
)

func main() {
    service := ":55555"
    tcpAddr, err := net.ResolveTCPAddr("tcp", service)
    checkError(err)
    listener, err := net.ListenTCP("tcp", tcpAddr)
    checkError(err)
    fmt.Printf("[*] Server up, port %s\n", service[1:])
    for {
        conn, err := listener.Accept()
        if err != nil {
            continue
        }
        go handleClient(conn)
    }
}

func handleClient(conn net.Conn) {
    defer conn.Close()
    conn.SetReadDeadline(time.Now().Add(10 * time.Second))
    fmt.Println("[*] Client accept!")

    messageBuf := make([]byte, 1024)
    messageLen, err := conn.Read(messageBuf)
    checkError(err)

    message := messageBuf[:messageLen]
    peerPub := new(big.Int).SetBytes(message)

    base, myExp, modulus := encryption.FFDHE_key_gen("2048")
    myPub := encryption.FFDHE(base, myExp, modulus)

    myPri := encryption.FFDHE(peerPub, myExp, modulus)
    fmt.Println("[+] DH Public Key :", myPub)
    fmt.Println("[+] DH Private Key :", myPri)

    conn.SetWriteDeadline(time.Now().Add(10 * time.Second))
    conn.Write(myPub.Bytes())

    bytesPriKey := myPri.Bytes()
    //secret := []byte("secret key")
    key, nonce := utils.Gen_key_and_iv(bytesPriKey, 32, 12, "sha256")
    plaintext := []byte("Hello, World!!")
    c := encryption.Chacha20_encrypt(key, 1, nonce, plaintext)
    fmt.Printf("[+] Cipher text : % x\n", c)

    conn.SetWriteDeadline(time.Now().Add(10 * time.Second))
    conn.Write(c)

}

func checkError(err error) {
    if err != nil {
        fmt.Fprintf(os.Stderr, "fatal: error: %s", err.Error())
        os.Exit(1)
    }
}