Initial commit

network/crypt_conn.go

@@ -0,0 +1,78 @@
+package network
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+
+	"github.com/Andoryuuta/Erupe/network/crypto"
+)
+
+// CryptConn represents a MHF encrypted two-way connection,
+// it automatically handles encryption, decryption, and key rotation via it's methods.
+type CryptConn struct {
+	conn                        net.Conn
+	readKeyRot                  uint32
+	sendKeyRot                  uint32
+	sentPackets                 int32
+	prevSendPacketCombinedCheck uint16
+}
+
+// NewCryptConn creates a new CryptConn with proper default values.
+func NewCryptConn(conn net.Conn) *CryptConn {
+	cc := &CryptConn{
+		conn:                        conn,
+		readKeyRot:                  995117,
+		sendKeyRot:                  995117,
+		sentPackets:                 0,
+		prevSendPacketCombinedCheck: 0,
+	}
+	return cc
+}
+
+// ReadPacket reads an packet from the connection and returns the decrypted data.
+func (cc *CryptConn) ReadPacket() ([]byte, error) {
+
+	// Read the raw 14 byte header.
+	headerData := make([]byte, CryptPacketHeaderLength)
+	_, err := io.ReadFull(cc.conn, headerData)
+	if err != nil {
+		return nil, err
+	}
+
+	//fmt.Printf("Header: %s\n", hex.Dump(headerData))
+
+	// Parse the data into a usable struct.
+	cph, err := NewCryptPacketHeader(headerData)
+	if err != nil {
+		return nil, err
+	}
+
+	// Now read the encrypted packet body after getting its size from the header.
+	encryptedPacketBody := make([]byte, cph.DataSize)
+	_, err = io.ReadFull(cc.conn, encryptedPacketBody)
+	if err != nil {
+		return nil, err
+	}
+
+	// Update the key rotation before decrypting.
+	if cph.KeyRotDelta != 0 {
+		cc.readKeyRot = (uint32(cph.KeyRotDelta) * (cc.readKeyRot + 1))
+	}
+
+	out, combinedCheck, check0, check1, check2 := crypto.Decrypt(encryptedPacketBody, cc.readKeyRot, nil)
+	if cph.Check0 != check0 || cph.Check1 != check1 || cph.Check2 != check2 {
+		fmt.Printf("got c0 %X, c1 %X, c2 %X\n", check0, check1, check2)
+		fmt.Printf("want c0 %X, c1 %X, c2 %X\n", cph.Check0, cph.Check1, cph.Check2)
+		return nil, errors.New("decrypted data checksum doesn't match header")
+	}
+
+	_ = combinedCheck
+	/*
+		fmt.Printf("cc %X, c0 %X, c1 %X, c2 %X\n", combinedCheck, check0, check1, check2)
+		fmt.Printf("cc %X, c0 %X, c1 %X, c2 %X\n", cph.PrevPacketCombinedCheck, cph.Check0, cph.Check1, cph.Check2)
+		fmt.Printf("cph: %+v\n", cph)
+	*/
+	return out, nil
+}