monorepo

Co-authored-by: Malte Poll <mp@edgeless.systems>
Co-authored-by: katexochen <katexochen@users.noreply.github.com>
Co-authored-by: Daniel Weiße <dw@edgeless.systems>
Co-authored-by: Thomas Tendyck <tt@edgeless.systems>
Co-authored-by: Benedict Schlueter <bs@edgeless.systems>
Co-authored-by: leongross <leon.gross@rub.de>
Co-authored-by: Moritz Eckert <m1gh7ym0@gmail.com>

coordinator/util/util.go

@@ -0,0 +1,70 @@
+package util
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"math/big"
+	"net"
+
+	"golang.org/x/crypto/hkdf"
+)
+
+// DeriveKey derives a key from a secret.
+//
+// TODO: decide on a secure key derivation function.
+func DeriveKey(secret, salt, info []byte, length uint) ([]byte, error) {
+	hkdf := hkdf.New(sha256.New, secret, salt, info)
+	key := make([]byte, length)
+	if _, err := io.ReadFull(hkdf, key); err != nil {
+		return nil, err
+	}
+	return key, nil
+}
+
+// GenerateCertificateSerialNumber generates a random serial number for an X.509 certificate.
+func GenerateCertificateSerialNumber() (*big.Int, error) {
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	return rand.Int(rand.Reader, serialNumberLimit)
+}
+
+// GenerateRandomBytes reads length bytes from getrandom(2) if available, /dev/urandom otherwise.
+func GenerateRandomBytes(length int) ([]byte, error) {
+	nonce := make([]byte, length)
+	if _, err := rand.Read(nonce); err != nil {
+		return nil, err
+	}
+	return nonce, nil
+}
+
+func GetIPAddr() (string, error) {
+	conn, err := net.Dial("udp", "8.8.8.8:80")
+	if err != nil {
+		return "", err
+	}
+	defer conn.Close()
+
+	localAddr := conn.LocalAddr().(*net.UDPAddr)
+
+	return localAddr.IP.String(), nil
+}
+
+func GetInterfaceIP(netInterface string) (string, error) {
+	netif, err := net.InterfaceByName(netInterface)
+	if err != nil {
+		return "", fmt.Errorf("could not find interface %s: %w", netInterface, err)
+	}
+	addrs, err := netif.Addrs()
+	if err != nil {
+		return "", fmt.Errorf("could not retrieve interface ip addresses %s: %w", netInterface, err)
+	}
+	for _, addr := range addrs {
+		if ipn, ok := addr.(*net.IPNet); ok {
+			if ip := ipn.IP.To4(); ip != nil {
+				return ip.String(), nil
+			}
+		}
+	}
+	return "", fmt.Errorf("interface %s don't have an ipv4 address", netInterface)
+}