Refactor funding request, will separate to multiple files later

lnwire/lnwire.go

@@ -0,0 +1,236 @@
+package lnwire
+
+import (
+	"encoding/binary"
+	"fmt"
+	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcutil"
+	"io"
+)
+
+//Actual pkScript, not redeemScript
+type PkScript []byte
+
+type CreateChannel struct {
+	ChannelType           uint8
+	OurFundingAmount      btcutil.Amount
+	OurReserveAmount      btcutil.Amount
+	MinFeePerKb           btcutil.Amount //higher of both parties
+	MinTotalFundingAmount btcutil.Amount
+
+	//CLTV lock-time to use
+	LockTime uint32
+
+	//Who pays the fees
+	//0: (default) channel initiator
+	//1: split
+	//2: channel responder
+	FeePayer uint8
+
+	OurRevocationHash   [20]byte
+	TheirRevocationHash [20]byte
+	OurPubkey           *btcec.PublicKey
+	TheirPubkey         *btcec.PublicKey
+	DeliveryPkScript    PkScript //*MUST* be either P2PKH or P2SH
+
+	OurInputs   []*wire.TxIn
+	TheirInputs []*wire.TxIn
+}
+
+//Writes the big endian representation of element
+//Unified function to call when writing different types
+//Pre-allocate a byte-array of the correct size for cargo-cult security
+//More copies but whatever...
+func writeElement(w io.Writer, element interface{}) error {
+	var err error
+	switch e := element.(type) {
+	case uint8:
+		var b [1]byte
+		b[0] = byte(e)
+		_, err = w.Write(b[:])
+		if err != nil {
+			return err
+		}
+	case uint32:
+		var b [4]byte
+		binary.BigEndian.PutUint32(b[:], uint32(e))
+		_, err = w.Write(b[:])
+		if err != nil {
+			return err
+		}
+	case btcutil.Amount:
+		var b [8]byte
+		binary.BigEndian.PutUint64(b[:], uint64(e))
+		_, err = w.Write(b[:])
+		if err != nil {
+			return err
+		}
+	case *btcec.PublicKey:
+		var b [33]byte
+		serializedPubkey := e.SerializeCompressed()
+		if len(serializedPubkey) != 33 {
+			return fmt.Errorf("Wrong size pubkey")
+		}
+		copy(b[:], serializedPubkey)
+		_, err = w.Write(b[:])
+		if err != nil {
+			return err
+		}
+	case [20]byte:
+		_, err = w.Write(e[:])
+		if err != nil {
+			return err
+		}
+	case PkScript:
+		scriptLength := len(e)
+		//Make sure it's P2PKH or P2SH size or less
+		if scriptLength > 25 {
+			return fmt.Errorf("PkScript too long!")
+		}
+		//Write the size (1-byte)
+		err = binary.Write(w, binary.BigEndian, uint8(scriptLength))
+		if err != nil {
+			return err
+		}
+		//Write the data
+		_, err = w.Write(e)
+		if err != nil {
+			return err
+		}
+	case []*wire.TxIn:
+		//Append the unsigned(!!!) txins
+		//Write the size (1-byte)
+		if len(e) > 127 {
+			return fmt.Errorf("Too many txins")
+		}
+		err = binary.Write(w, binary.BigEndian, uint8(len(e)))
+		if err != nil {
+			return err
+		}
+		//Append the actual TxIns (Size: NumOfTxins * 36)
+		//Do not include the sequence number to eliminate funny business
+		for _, in := range e {
+			//Hash
+			var h [32]byte
+			copy(h[:], in.PreviousOutPoint.Hash.Bytes())
+			_, err = w.Write(h[:])
+			if err != nil {
+				return err
+			}
+			//Index
+			var idx [4]byte
+			binary.BigEndian.PutUint32(idx[:], in.PreviousOutPoint.Index)
+			_, err = w.Write(idx[:])
+			if err != nil {
+				return err
+			}
+		}
+	default:
+		return fmt.Errorf("Unknown type in writeElement: %T", e)
+	}
+
+	return nil
+}
+
+func readElement(r io.Reader, element interface{}) error {
+	var err error
+	switch e := element.(type) {
+	case *uint32:
+		var b [4]byte
+		_, err = io.ReadFull(r, b[:])
+		if err != nil {
+			return err
+		}
+		*e = binary.BigEndian.Uint32(b[:])
+	}
+
+	return nil
+}
+
+//Serializes the fundingRequest from the CreateChannel struct
+//Writes the data to w
+func (c *CreateChannel) SerializeFundingRequest(w io.Writer) error {
+	var err error
+
+	//Fund request byte
+	err = binary.Write(w, binary.BigEndian, uint8(0x30))
+	if err != nil {
+		return err
+	}
+
+	//Channel Type
+	//default to 0 for CLTV-only
+	err = writeElement(w, c.ChannelType)
+	if err != nil {
+		return err
+	}
+
+	//Our Funding Amont
+	err = writeElement(w, c.OurFundingAmount)
+	if err != nil {
+		return err
+	}
+
+	//Our Channel Minimum Capacity
+	err = writeElement(w, c.MinTotalFundingAmount)
+	if err != nil {
+		return err
+	}
+
+	//Our Revocation Hash
+	err = writeElement(w, c.OurRevocationHash)
+	if err != nil {
+		return err
+	}
+
+	//Our Commitment Pubkey
+	err = writeElement(w, c.OurPubkey)
+	if err != nil {
+		return err
+	}
+
+	//Our Delivery PkHash
+	err = writeElement(w, c.OurRevocationHash)
+	if err != nil {
+		return err
+	}
+
+	//Our Reserve Amount
+	err = writeElement(w, c.OurReserveAmount)
+	if err != nil {
+		return err
+	}
+
+	//Minimum Transaction Fee Per KB
+	err = writeElement(w, c.MinFeePerKb)
+	if err != nil {
+		return err
+	}
+
+	//LockTime
+	err = writeElement(w, c.LockTime)
+	if err != nil {
+		return err
+	}
+
+	//FeePayer
+	err = writeElement(w, c.FeePayer)
+	if err != nil {
+		return err
+	}
+
+	//Delivery PkScript
+	err = writeElement(w, c.DeliveryPkScript)
+	if err != nil {
+		return err
+	}
+
+	//Append the actual Txins
+	err = writeElement(w, c.OurInputs)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}