Release v0.3.0

vendor/github.com/ltcsuite/ltcd/wire/msggetdata.go

@@ -0,0 +1,133 @@
+// Copyright (c) 2013-2015 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package wire
+
+import (
+	"fmt"
+	"io"
+)
+
+// MsgGetData implements the Message interface and represents a bitcoin
+// getdata message.  It is used to request data such as blocks and transactions
+// from another peer.  It should be used in response to the inv (MsgInv) message
+// to request the actual data referenced by each inventory vector the receiving
+// peer doesn't already have.  Each message is limited to a maximum number of
+// inventory vectors, which is currently 50,000.  As a result, multiple messages
+// must be used to request larger amounts of data.
+//
+// Use the AddInvVect function to build up the list of inventory vectors when
+// sending a getdata message to another peer.
+type MsgGetData struct {
+	InvList []*InvVect
+}
+
+// AddInvVect adds an inventory vector to the message.
+func (msg *MsgGetData) AddInvVect(iv *InvVect) error {
+	if len(msg.InvList)+1 > MaxInvPerMsg {
+		str := fmt.Sprintf("too many invvect in message [max %v]",
+			MaxInvPerMsg)
+		return messageError("MsgGetData.AddInvVect", str)
+	}
+
+	msg.InvList = append(msg.InvList, iv)
+	return nil
+}
+
+// BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
+// This is part of the Message interface implementation.
+func (msg *MsgGetData) BtcDecode(r io.Reader, pver uint32, enc MessageEncoding) error {
+	count, err := ReadVarInt(r, pver)
+	if err != nil {
+		return err
+	}
+
+	// Limit to max inventory vectors per message.
+	if count > MaxInvPerMsg {
+		str := fmt.Sprintf("too many invvect in message [%v]", count)
+		return messageError("MsgGetData.BtcDecode", str)
+	}
+
+	// Create a contiguous slice of inventory vectors to deserialize into in
+	// order to reduce the number of allocations.
+	invList := make([]InvVect, count)
+	msg.InvList = make([]*InvVect, 0, count)
+	for i := uint64(0); i < count; i++ {
+		iv := &invList[i]
+		err := readInvVect(r, pver, iv)
+		if err != nil {
+			return err
+		}
+		msg.AddInvVect(iv)
+	}
+
+	return nil
+}
+
+// BtcEncode encodes the receiver to w using the bitcoin protocol encoding.
+// This is part of the Message interface implementation.
+func (msg *MsgGetData) BtcEncode(w io.Writer, pver uint32, enc MessageEncoding) error {
+	// Limit to max inventory vectors per message.
+	count := len(msg.InvList)
+	if count > MaxInvPerMsg {
+		str := fmt.Sprintf("too many invvect in message [%v]", count)
+		return messageError("MsgGetData.BtcEncode", str)
+	}
+
+	err := WriteVarInt(w, pver, uint64(count))
+	if err != nil {
+		return err
+	}
+
+	for _, iv := range msg.InvList {
+		err := writeInvVect(w, pver, iv)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Command returns the protocol command string for the message.  This is part
+// of the Message interface implementation.
+func (msg *MsgGetData) Command() string {
+	return CmdGetData
+}
+
+// MaxPayloadLength returns the maximum length the payload can be for the
+// receiver.  This is part of the Message interface implementation.
+func (msg *MsgGetData) MaxPayloadLength(pver uint32) uint32 {
+	// Num inventory vectors (varInt) + max allowed inventory vectors.
+	return MaxVarIntPayload + (MaxInvPerMsg * maxInvVectPayload)
+}
+
+// NewMsgGetData returns a new bitcoin getdata message that conforms to the
+// Message interface.  See MsgGetData for details.
+func NewMsgGetData() *MsgGetData {
+	return &MsgGetData{
+		InvList: make([]*InvVect, 0, defaultInvListAlloc),
+	}
+}
+
+// NewMsgGetDataSizeHint returns a new bitcoin getdata message that conforms to
+// the Message interface.  See MsgGetData for details.  This function differs
+// from NewMsgGetData in that it allows a default allocation size for the
+// backing array which houses the inventory vector list.  This allows callers
+// who know in advance how large the inventory list will grow to avoid the
+// overhead of growing the internal backing array several times when appending
+// large amounts of inventory vectors with AddInvVect.  Note that the specified
+// hint is just that - a hint that is used for the default allocation size.
+// Adding more (or less) inventory vectors will still work properly.  The size
+// hint is limited to MaxInvPerMsg.
+func NewMsgGetDataSizeHint(sizeHint uint) *MsgGetData {
+	// Limit the specified hint to the maximum allow per message.
+	if sizeHint > MaxInvPerMsg {
+		sizeHint = MaxInvPerMsg
+	}
+
+	return &MsgGetData{
+		InvList: make([]*InvVect, 0, sizeHint),
+	}
+}